Blood Glucosse Level nd Hepatic Functional Status Of Alloxan Induced Diabetic Wistar Rats Following Combinatorial Administration of Monosidium Glutamate And Alpha Tocopherol

Abstract

This work is aimed at evaluating the antidiabetic effect and liver function indices of MSG and alpha tocopherol in alloxan induced diabetic albino rats. Thirty rats were grouped into five groups, 1, 2, 3, 4, and 5. Diabetic was induced in all expect group 1 which served as the normal control. Groups 2 and 3 which are the two test groups was treated with MSG and alpha  tocopherol were administered to the animals once daily for five weeks.  Group 4 served as the negative control and was not treated while group 5 was the positive control and treated with a standard (Glucophage containing metformin). The liver function parameters were determined using spectrophotometric methods. The result showed significant difference in Alkaline phosphatase, Alanine transferase (P<0.005) when compared with other treatment group.  In the case of total bilirubin and conjugated bilirubin, there was no significant difference (P>0.005) when comparism is made across the groups. Finally, the present study showed that co-administration of MSG and alpha tocopherol at dose 2000 and 2200 mg/kg bw ameliorated hepatic dysfunction.

CHAPTER ONE

• INTRODUCTION/LITERATURE REVIEW

The liver is the largest visceral organ of homeostasis in vertebrates. The hepatocytes exhibit broad capacity to metabolize diverse biomolecules and inorganic substances as well as carryout storage, immunological and detoxification capabilities. Hepatic enzymes are released into systemic circulation following liver necxrosis  and therefore, are used as diagnostic indicators  for tissue damage (Sanjiv C., 2002). Accordingly  elevations in plasama activities of alanine amino transferase (ALT), aspartate amino transerase (AST)  and alkaline phosphatase (ALP), referred to as non-functional plasma enzymes are diagnostic of hepatic dysfunction (Onyema  OO, et al., 2006).  In addition, several metabolites such as bilirubin  which are of hepatic origin, are useful biomarkers of chronic and acute hepatic diseases (Suzuki Y et al., ).

Diabetes mellitus (DM) is clinically referred to a large group of disease resulting in hyperglycemia and related metabolic disorders elicited by overwhelming oxidative stress (Ergun-longmire B et al., 2000). Etiological considerations are often used for the classification DM as well as approach to treatment and management schemes for the disease. Diabetes mellitus (Type 1 Diabetes mellitus) and non-insulin dependent diabetes mellitus (Type 2 Diabetes mellitus).  The Type 1 Diabetes mellitus is elicited by a result of peripheral tissue resistance to insulin action (Bahadoram Z, et al., 2013). Clinical investigations showed that Type 1 Diabetes mellitus arise from viral or autoimmune destruction of the B-cells of the welt of langerhans. Accordingly Type 1 Diabetes mellitus patients show presence of auto-antibodies to Islet cells in their blood samples or evidence of viral-induced carcinoma following pancreatic biopsy. Types 1 and Type 2 diabetes mellitus are characterized by low glucose uptake by peripheral tissues, especially the muscle and adipose tissue. Epidemiological survey showed  that patients suffering from autoimmune mediated Diabetes mellitus accounts for about 10-15% of all diabetes mellitus population (Ergun-Longmire B, et al., 2000). current estimates mellitus and projection revealed that this statistics will double by 2030 (Kuma A, and singh V 2010). Genetic causes are for the most part, implicate by hyper insulinemia in individuals with obesity and Type 2 Diabetes mellitus (Calle EE et al., 2003).

Monosodium glutamate (MSG) is a major dietary component, which intensifies the savory flavour in foods worldwide (Nwaje et al., 2015). Different market brands of MSG serve to improve the palatability of meals and as such stimulate and enhance appetite. Despite reports on toxic outcomes in animal models exposed to MSG and MSG containing diets, the food and Drug Administration (FDA) of the united states still consider MSG as a safe and as such component et al., of food  Generally Recognized as safe (GRAS) (Eweka AO 2011). Accordingly, MSG is permitted as a safe food additive, which is often consumed without specific requisite upper limit to average daily intake (Rogers PJ and Blundeel JE, 1990). It is common knowledge that Diabetes mellitus individuals consume variety of delicacies containing MSG, which may also contain multitudes of other food components like ascorbic acids.Hydrophilic antioxidant. Alloxan-induced Diabetes mellitus rats represent and experimental prototype for type 1 diabetes mellitus.

The present study investigated the capacity of combined administration of MSG, and -tocopherol to reverse altered hepatocyte using standard biomarkers serum alanine transaminase (ALT) and aspartate trnsaminase (AST), alkaline phosphatase (ALP) acitivites as well as serum total bilirubin and conjugated bilirubin in wistar rats models in Type 1 DM Wister rat models.

1.1Literature Review

1.1.1Diabetes Mellitus

Diabetes mellitus often referred to simply as diabetes is a syndrome of disorder in metabolism, usually due to a combination of hereditary and environmental causes, resulting in abnormal high blood sugar level (hyperglycemia) (Tierney et al., 2002) Paulsen (1998) saw Diabetes mellitus as a syndrome of disturbed intermediary metabolism caused by inadequate insulin secretion or impaired insulin action, or both. Blood glucose levels are controlled by a complex interaction of multiple chemicals and hormones in the body including the hormone insulin made in the beta cells of the pancreas. Diabetes mellitus consists of a group of syndromes characterized by hyperglyamia, altered metabolism of lipids, carbohydrates and proteins, and an increased risk of complications from vascular disease criteria for the diagnosis of diabetes mellitus have been proposed by several medical organizations (WHO, 1999). The American Diabetes Association  criteria include  symptoms of diabetes mellitus aspolyuria, polydipsia and unexplained weight loss a random plasma glucose concentration of greater than 200mg/dl (11.1mm) a fasting plasma glucose concentration of greater than 126mg/dl (7mm) or a plasma glucose concentration of greater than 200mg/dl (11mm) 2 hours after the ingestion of a oral glucose load (expert committee on the Diagnoses an Treatment of Diabetes Mellitus, 2003).

1.1.2Etiology of Diabetes Mellitus

Etiological considerations are often used for the classification diabetes mellitus as well as approach to treatment and management schemes for the disease. Diabetes mellitus is a broadly classified into two groups; insulin dependent  diabetes mellitus (Type 1 diabetes mellitus and non-insulin dependent diabetes mellitus (Type 2 diabetes mellitus). The type 1 diabetes mellitus is elicited by insulin insufficiency in plasma, where a type 2 diabetes mellitus arise from viral or autoimmune destruction of the -cells of the Islet of langerhans. Accordingly, Type 1 DM patients show presence of auto-antibodies to Islet cells in their blood samples or viral-induced carcinoma of the pancreas.

1.1.3 Epidemiology of Diabetes Mellitus

In recent years, developed and developing nations have witnessed an explosive increase in the prevalence of diabetes mellitus predominately related to life style changes and the resulting surge in obesity (king  et al., 1998). The metabolic consequence of prolonged hyperglycemia and dyslipidemia,  including accelerated atherosclerosis, chronic kidney  disease  and blindness pose an enormous burden on patients with DM and on the public health system (Goodman and Gilman, 2006). In 2000, according to the world Health organization, at least 171 million people worldwide suffer from diabetes, or 2.8% of the population. (Roglic et al., 2004) its incidence is increasing rapidly, and it is estimated that by the year 2030, this number will almost double (Roglic et al., 2004).Diabetes mellitus occurs throughout the world but is more common (especially types 2) in the more developed countries (Rother, 2007). The greatest increase on prevalence is, however, expected to occur in Asia and Africa, where most patients will likely be found by 2030 (Roglic et al., 2004). The increase in incidence of diabetes in developing countries follows the trend of urbanization and lifestyle changes, perhaps most importantly a “western style” diet.

For past 20 years, diabetes rates in North America have been increasing substantially. In 2008 there were about 24 million people with diabetes in the united State alone, of which 5.7 million people remain undiagnosed, over one million people are estimated to have pre-diabetes (CDC, 2000). About 5%-10% of diabetes cases in North America are types 1 with the rest being type 2. The American Diabetes are types 1 with the rest being type 2.The American Diabetes Association point out the 2003 assessment of the National center of chronic disease prevention and Health promotion that 1 in 3 Americans born after 200 will develop diabetes in their lifetime (Narayan et al., 2003). The vast majority of diabetic patients have type 2 diabetes mellitus. In the united state, about 90% of all diabetic patients have types diabetes mellitus. Both type 1 and type 2 DM are increasing in frequency. The reason for the increase of type 1 DM is not known. The genetic basis of type 2 DM cannot change in such a short time thus other contributory factors including increasing age, obesity, sedentary lifestyle and low weight, must account for this dramatic increase.

1.1.4 Pathophysiology 

Genetic causes are, for the most part, implicated in hyper insulinemia in individuals with obesity and Type 2 Dm (Calle et al., 2003: Coughlin et al., 2004). In the course of time, Type 2 Dm suffers exhibit increased insulin deficiency in plasma mediated by glucosamine and lipid toxicities to the – cells of the Islets, which often recourse to management strategy of insulin replacement therapy (Ergun-Longmire and maclaren, 2000).

1.1.5 complications

Epidemiological studies revealed that the incidence of diabetes mellitus is on the rise worldwide, in spite of remarkable progress in treatment and preventive strategies against the disease (Ergun-Longmire and Maclaren, 2000) micro-vascular and macro-vascular complications; namely, retinopathy, nephropathy, neuropathy as well as atherosclerosis and cardiovascular disease are major causes of diabetes mellitus mortality and morbidity (Tiwari et al., 2013; Samioglu et al., 2013; Pitocco et al., 2012; Yan, 2014; Forouhi and Wareham, 2014; Ghosh et al., 2015). Among several environmental factors associated with diabetes mellitus pathogenesis, adjustments in dietary habits such as increasing intake of pro-oxidants containing food substance have been linked to rapid rising prevalence of diabetes mellitus.

1.1.6 Classification of Diabetes Mellitus

Type 1 diabetes mellitus is characterized by loss of the  insulin producing beta cells of the Islets of langerhans in the  pancreas leading to insulin  deficiency. This type of diabetes can be further classified as immune mediated or idiopathic. The majority of type 1 diabetes is of the immune mediated  nature, where beta cell loss is a T-cell mediated autoimmune  attack (Rother, 2007). There is no known preventive measure against type 1 diabetes, which causes approximately 10% of diabetes mellitus cases in North American and Europe. Most affected people are otherwise healthy and of a health weight when onset occurs. Sensitivity and responsiveness to insulin are usually normal, especially in the early stages. type 1 diabetes can affect children or adults but was traditionally termed “juvenile diabetes” because it represents  a majority of the diabetes cases in children. (Export committee on the Diagnosis and Treatment of Diabetes Mellitus 2005).

1.1.6.1 Type 2 Diabetes Mellitus

Type 2 diabetes mellitus is characterized differently and is due to insulin resistance insulin sensitivity combined with relatively reduced insulin secretion which in some case becomes absolute. The defective responsiveness of body tissues to insulin almost certainly involves the insulin receptor in cell membranes. However, the specific detects are not known. Diabetes mellitus due to known specific defect are classified separately. In the early stage of type 2 diabetes, the predominant abnormality is reduced insulin sensitivity, characterized by elevated levels of insulin in the blood. At this stage hyperglycemia can be reversed by a variety of measures and medications that improve insulin sensitivity or reduced glucose production by the liver. As the disease progresses, the impairment of insulin secretion worsens, and therapeutic replacement of insulin often becomes necessary. There are numerous theories as to the exact cause and mechanism in type 2 diabetes (Riserus, 2009). Central obesity (fat concentrated around the waist in relation to abdominal organ, but subcutaneous fat) is known to predispose individuals to insulin resistance. Abdominal fat is especially active hormonally, secreting a group of hormone called adipokines that may possibly impair glucose tolerance obesity  is found in approximately  55% of patients  diagnosed with type 2 diabetes. Other factors include aging (about 20% of elderly patients in North America have diabetes) and family history (type 2 is much more common in those with close relatives who have had it) in the last decade, type 2 diabetes has increasingly begun to affect children and adolescents, likely in connection with the increased prevalence of childhood obesity seen in recent decades in some places (Rosebloon and Silustein, 2003). Environmental exposures may contribute to recent increases in the rate of type 2 diabetes. A positive correlation has been found between the concentration in the urine of bisphenol A, a constituent of polycarbonate plastic, and the incidence of type 2 diabetes.

1.1.6.2 Gestation Diabetes Mellitus  

Gestational diabetes mellitus (GDM) resembles type 2 diabetes in several respects, involving a combination of relatively inadequate insulin secretion and responsiveness. It occurs in about 2%-55 of all pregnancies and may improve or disappear after delivery. Gestational diabetes is fully treatable but 20%-50% of affected women develop type2 diabetes later in life (Lawrence et al., 2005). Even though it may be transient, untreated gestational diabetes can damage the health of the fetus or mother. Risks to the baby include macrosomia (high birth weight) congenital cardiac and central nervous system anomalies, and skeletal muscle malformations. A 2008 study completed in the united State found that the more American women are entering pregnancy with pre-exisitng diabetes (LyssenKo et al., 2008). In fact the rate of diabetes in expected mothers has more than double in the past 6 years (Lawrence et al., 2005). This is particularly problematic as diabetes raises the risk of complication during pregnancy as well as increasing the potential that the children of diabetic mothers will also become diabetic in future.

1.1.6.3 Diagnostic Tests

Some of the commonly employed tests in the diagnosis of diabetes mellitus include oral glucose tolerance test (OGTT) and in some cases, fasting blood glucose (FBS).

Oral Glucose tolerance Test (OGTT)

This is the most accepted and widely applied test for the diagnosis of diabetes mellitus. In this test, the patient must fast for 14 hours and should discontinue glucose-altering medication at least 3 days prior to test.The patient must no smoke cigarette or drink alcohol or coffee just before and during the test, and patient must not be carbohydrate depleted 3 days prior to the test (George, 1992). After fasting for about 14 hours, the patient is given an oral glucose load of 75-100g and blood sample is withdrawn every 30 minutes for the next 2 hours  since in 2 hours the blood glucose level (< 200 mg%) in a non- diabetic patient is expected to have normalized. But in diabetic, the plasma glucose level is higher than 200mg%. (Aguwa and Omole, 2004), and returns to the baseline more slowly than it does in normal or non-diabetics (Ganong, 1999).

Fasting Blood Glucose (FBG).

Blood sample is collected and analyzed after the patient has fasted over night, after a period of unimpaired carbohydrate intake. The normal range of fasting blood glucose is 70-110mg% when collected from the venous blood (Aguwa and Omole, 2004).

1.1.6.4 Sign and Symptoms

The classical fried of diabetes symptoms include polyuria, polydipsia, and polyphagia, which are, respectively, frequent urination, increased thirst and consequent increased fluid intake, and increase appetite symptoms may develop quite rapidly (week or months) in type I diabetes particularly in children.

However, in type 2 diabetes symptoms usually develop much more slowly and may be subtle or completely absent. Type I diabetes may also cause a rapid and significant weight loss (despite normal or even increased eating) and irreducible fatigue. All of these symptoms except weight loss can also manifest in type2 diabetes in patients whose diabetes is poorly controlled (Santaguida et al., 2008). When the glucose concentration in the blood is praised beyond its renal threshold, desorption of glucose in the proximal renal tubuli is incomplete, and part of the glucose remains in the urine (glycosuria). This increases the osmotic pressure of the urine and inhibits reabsorption of water by the kidney, resulting in increased urine production (polyuria) and increased thirst (Tarnow et al., 2008). Prolonged high blood glucose leads to changes in the shape of the lenses of the eyes, resulting in vision changes; sustained sensible glucose control usually returns the lens to its original shape. Blurred vision is a common complaint leading to a diabetes diagnosis. Type 1 DM should always be suspected in cases of rapid vision change (Theadore et al., 2008). Patients (usually with type 1 diabetes) may also initially present with diabetes ketoacidosis (DKA) an extreme state of metabolic dysregulation characterized by the smell of acetone on the patients breath; a rapid, deep breathing known as Kussmaul breathing; polyuria, nausea, vomiting and abdominal pain, and any of many altered states of consciousness or arousal (Such as hostility and mania or equally, confused and lethargy).

In severe DKA, coma may follow, progressing to death. Diabetic ketoacidosis is a medical emergency and requires immediate hospitalization. A rarer but equally severe possibility is hyper osmolar non ketotic state which is more common in type 2 diabetes and is mainly the result of dehydration due to loss of body water. Often, the patient has been drinking extreme amounts of sugar containing drinks, leading to a vicious circle is regard to the water loss (Genuth, 2006; Sniderman et al., 2007).

1.1.6.5 Prevention of Diabetes

Type 2 diabetes risk can be reduced in many cases by making changes in diet and increasing physical activity (Lindstron et al., 2006; Knowler et al., 2002). The American Diabetes Association (ADA) recommends maintaining a healthy weight getting at least 21/2 hours of exercise per week, having a modest fat intake, and eating sufficient fibre. The ADA does not recommend alcohol consumption and heart disease is termed the French paradox. There is  inadequate evidence that eating foods of low glycogenic index is clinically helpful despite recommendations and suggested deemphasizing this approach. (Bantle et al., 2006). There are numerous studies which suggest connections between some aspects of type 2 diabetes with ingestion of certain foods or with some drugs. Some studies have shown delayed progression to diabetes in presupposed patients through prophylacticuse of metformin (Knolwer et al., 2002), rosiglita zone (Gerstein et al., 2006), or valsartan (Kjeldsen et al., 2006).  In patients on hydroxyl chloroquine for rheaumatoid arthritis, incidence of diabetes was reduced by 77% though caused mechanism is unclear (Wasko et al., 2007). Breast feeding may also be associated with the prevention of type 2 of the disease in mothers (Stueb et al., 2005). Clear evidence for these and any of many other connections between foods and supplements and diabetes is sparse to data; none ,  despite secondary claims for  or against is sufficiently well established to justify as a standard clinical approach.

1.1.6.6 Treatment and Management

Diabetes mellitus is currently a chronic disease without a cure, and medical emphasis must necessarily be on managing/avoiding possible short term as well as long-term diabetes-related problems. There is an exceptionally important  role for patient education, dietetic support sensible. Exercise self-monitoring of blood glucose, with the goal of keeping both short-term blood glucose levels, and long term levels as well, within acceptable bounds careful control is needed to reduce the risk of long term complications. This is theoretically achievable with combinations of diet, exercise and weight loss (type 2) various oral diabetic drugs (type 2 only), and insulin use (type 1 and for type 2 not responding to oral medication, mostly those with extended duration diabetes). In addition, given the associated higher risks of cardiovascular disease, lifestyles modification should be undertaken to control blood pressure (Alder et al.,2000) and cholesterol by exercising more, smoking less or ideally not at all, consuming an appropriate diet, wearing diabetic socks, wearing diabetic  shoes, and if necessary, taking any of the several drugs to reduce blood pressure.

1.2 Alloxan

Alloxan (2, 4, 5, 6-tetraoxygpyrimidine; 2, 4, 5, 6,-pyrimidinetetrone) is an oxygenated pyrimidine derivative which is present as alloxan hydrate in aqueous solution. Brugnatelli originally isolated alloxan in 1818 and the name was given by Wohler and Liebig in 1838(Wohler and Liebig, 1838). Moreover, the compound was discovered by von liebig an Wohler in 1828 and has been regarded as one of the oldest named organic compounds that exist. One of the most potent methods to induce experimental diabetes mellitus is chemical induction by Alloxan. It is a well-known diabetogenic agent that is sued to induce Type 1 diabetes in experimental animals. Alloxan is a urea derivative which cause selective necrosis of the -cells of pancreatic islets. In addition, if has been widely used to produce experimental diabetes in animals such as rabbits, rats, mice and dogs with different grades of disease severity by varying the dose of alloxan used. As it has been widely accepted that alloxan hselectively destroys the insulin-producing beta-cells  found in the pancreas, hence it is used to induce diabetes inlaboratro animals. The toxic action of alloxan on pancreatic beta cells involve oxidation of essential  sulphydryl (-SH groups), inhibition of glucokinase  enzyme, generation of free radicals and disturbances in intracellular calcium homeostasis. The underlying mechanism involves the selective uptake of the compounds due to its structural similarity to glucose as well as highly efficient uptake mechanism of the pancreatic beta-cell. The aim of the present review is to explicate the mechanisms involved in alloxan induced induction of experimental diabetes mellitus. The name Alloxan emerged from the merging of two words, that is Allantoin  and oxaluric acid. Allantion is a product of uric acid excreted by the foetus in the allantois and oxaluric acid has been derived from oxalic acid and urea that is found in urine. Additionally, the alloxan model of diabetes induction was first describes in rabbits by Dunn, Sheehan and Mc Letchie in 1943. Alloxan was originally prepared by the oxidation of uric acid by nitric acid. The monohydrate is simultaneously prepared by oxidation of barbituric acid by chromium trioxide.

1.2.1 Mechanism of Action of Alloxan                  

        Alloxan induced diabetes has been commonly employed as an experimental model of insulin dependent diabetes mellitus. The mechanism of alloxan action has been thoroughly studied which currently can be characterized quite well. Several experimental studies have demonstrated that alloxan evokes a sudden rise in insulin secretion in the presence or absence of glucose which appeared just after alloxan treatment. This particular alloxan-induced insulin release occurs for short duration followed by the complete suppression of the islet response to glucose even when high concentrations of glucose were used. Further, the alloxan action in the pancreas is preceded by its rapid uptake by pancreatic beta cells that have been proposed to be one of the important features determining alloxan daiabetogenaicity. Moreover, in pancreatic beta cells, the reduction process occurs in the presence of different reducing agent like reduced glutathione (GSH), cysteine, ascorbate and protein-bound sufhydryl (-SH) groups. Alloxan reacts  with two- SH groups in the sugar binding site of glucokinase resulting in the formation of the disulfide bond and inactivation of the enzyme. As a result of alloxan reduction, dialuric acid is formed which is then re-oxidized back to alloxan establishing a redox cycle for the generation of reactive oxygen speicies (ROS) and superoxide radicals. The superoxide liberate ferri ions from ferreting and reduce them to ferrous and ferric ions in addition, superoxide radicals undergo disputation to yield hydrogen peroxide (H₂O₂) in the presence of superoxide dismutase. As a result, highly reactive hydroxyl radicals are formed according to the fenton reaction in the presence of ferrous and H₂O₂. Another mechanism that has been reported is the effect of ROS on the DNA of pancreatic islets.The fragmentation of DNA takes place in the beta cells exposed to alloxan that cause DNA damage, which stimulates Poly ADP-ribosylaton, a process participating in DNA repair. Antioxidants lay superoxide dismutase, catalase and the non enzymatic scavengers of hydroxyl radicals have been found to protect against alloxan toxicity. In addition, the disturbance in intracellular calcium homenstasis has also been reported to constitute an important step in the diabetogenic action of alloxan. It has been noted that alloxan elevates cytosolic free ca2+ concentration in the beta cells  of pancreatic islets. The calcium influx is resulted from the ability of alloxan to depolarize pancreatic beta cells that further opens voltage dependent calcium channels and enhances calcium entry into pancreatic cells. The increased concentration of ca2+ ion further contributes to supraphysiological insulin release that along with ROS has been noted to ultimately cause damage of beta cells of pancreatic islets.

1.3 Overview of Tocopherol (Vitamine)

Tocopherol which is also known as vitamin E is a group of eight compounds that include four tocopherols and four tocotricnols. All eight feature a chromane double ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals, and a hydrophobic side chain which allows for penetration into biological membranes. Both the tocopherols and tocotrienols occurs in a (alpha),  (beta), Y (gamma) and ∫(dalta) forms, as determined by the number and poisiton of methyl groups on the chromanol ring (brigelius flolic R and Traber MG, 1999) of the many different forms of vitamin E., gamma tocopherol (Y-tocopherol) is the most common form found in the North American diet (Bieri JG and Euarts RP, 1974).The most biologically active form of vitamin E in the diet. This variant can be found most abundantly in wheat germ oil sunflower oil and safflower oil (Reboul E et al., 2006). As fat soluble antioxidants, tocopherols interrupt the propayation of reactive oxygen species that spread through biological membranes or through fat when its lipid content undergoes oxidation by reacting with lipid radicals (Choe et al., 2009).

Figure 1.1: Structure of alpha Tocopherol

Worldwide, government organizations recommend adults consume in the range of 7 to 15mg per day. As of 2016, consumption is below recommendation according to worldwide summary of more than one hundred studies that reported a median dietary intake of 6.2mg per day for alpha-tocopherol (Peter S. et al., 2016). Research with alpha- tocopherol as a dietary supplement, with daily amounts as high as 200mg per day, has had mixed results. Population studies suggested  that people  who consumed foods  with more vitamin E or who chose on their  own to consume a vitamin E dietary supplement, had lower incidence of cardiovascular disease, cancer, dementia and other diseases, but placebocontrolled clinical trials could not always replicate these findings and there were some  indications, that vitamin E supplementation actually was associated with a modest increase in all-cause mortality (Miller ER et al., 2005). As of 2017, vitamin E continues to be a topic of active clinical research (Galli F et al., 2017).

Vitamin E was discovered 1922, isolated in 1935 and first synthesized in 1938.Because the vitamin activity was first identified as essential for fertilized eggs to result in liver births (in rats). It was given the name “tocopherol “from Greek words meaning birth and to bear or carry (Evans HM et al., 1922). Vitamin E is sold as a dietary supplement, either by itself or incorporated into a multivitamin product. It is also sold in topical products, although there is little evidence for any benefit (Sidgwick GP et al., 2015).

Vitamin E is described as functioning as an antioxidant a dose-ranging trial was conducted in people with chronic oxidative stress attributed to elevated serum cholesterol. Plasma f₂-isoprostane concentration was selected as a biomarker of free radical mediated lipid perxidiation. Only the two highest does-1600 and 3200 iu/day- significantly lowered f₂– isoprostane (Rebertsii et al., 2007).

1.3.1 Mechanism of Action of Vitamin e 

It involves the inhibition of the oxidation of LDL and the accumulation of  ox LDL in the  arterial wall. It also appears to reduce oxLDL induced apoptosis in human endothelial cells. Vitamin E. Inhibits protein kinase  C. (PKC) activity PKC plays a role in smooth muscle cell proliferation and thus, the inhibition of PKC results in  inhibition of smooth muscle cell proliferation, which is involved in a the genesis (miller, 2005). Vitamin E acts as a radical scavenger delitering and H atom to free radicals. At 323 kj/mol, the O-H bond in tocopherols is about 10% weaker than in most other pherols. This weak bond allows the vitamin to donate a hydrogen atom to the peroxyl radical and other free radicals, minimizing their damaging effect. The generated tocopheryl radical is relatively uncreative but revert to tocopherol by a redox reaction with a hydrogen donor such as vitamin C (Traber et al., 2011).

• Liver (Hepatic Status)

The liver is the largest solid organ and the largest   gland in the human body. It carries out over 500 essential tasks. It plays a role in detoxification, protein synthesis and the production of chemicals that help digest food. In humans it is located in the right upper quadrant of the abdomen, below the diaphragm its role in metabolism include the regulation of glycogen storage, decomposition of red blood cells and the production of hormones (Abdelmisih et al., 2010).

• Structure of the Liver

The liver is one of the most versatile and important organs. Weighting between 317 and 3.66 pounds (1b), or between 1.44 and 1.66 kilograms (kg) the liver is reddish-brown with a rubbery texture. It is situated above and to the left of texture. It is situated above and to the left of the stomach and below the lungs (Elaine, 2018). It is protected by the rib café. The liver has two large sections, called the right and the left lobes. The fall bladder sits under the liver, along with parts of the pancreas and intertines. The liver and the these organs work together to digest absorb and process food (Matthew, 2014). The lobes of the liver are separated by the falciform ligament a band of tissue that keeps it andnored to the diaphragm. A layer of fibrous tissue called Glisson’s capsule covers the outside of the liver. This capsule is further covered by the peritoneum, a membrane that forms the lining of the abdominal cavity.

The various functions of the liver are carried out by the liver cells or hepatocytes. These functions include;

• Functions of the liver

• Blood Supply: The liver receives a dual blood supply from the hepatic portal vein and hepatic arteries blood flows through the liver sinusoids and empties into the central vein of each lobule. The central view coalesces into hepatic veins; which leave the liver and drain into the inferior vena cava (Jelkmann, 2001).
• Bile Production: Bile helps the small intestine break down and absorb fats cholesterol and some vitamins. Bile consists of bile salt cholesterol, bilirubin, electrolytes and water.
• Absorbing and Metabolizing Bilirubin: Bilirubin formed by the breakdown of hemoglobin. The iron released from hemoglobin is stored in the liver or bone marrow and used to make the necessary generation of blood cells (Elaine, 2018).
• Supporting Blood Cloths: Vitamin Kis necessary for the creatin of certain coagulants that help clot the blood. Bile is essential for vitamin K absorption and is created in the liver. If the liver does not produce enough bile, clotting factors cannot be produced.
• Fat Metabolization:Bile breaks down fats and makes the blood easier to digest.
• Filters the Blood: The liver filters and removes compounds from the body, including hormone such as estrogen and aldosterone and compounds from outside the body, including alcohol and other drugs (Elaine K., 2018).

1.4.3 Liver Function Test

The liver function test is a group of test done to assess the functional capacity of the liver as well as any cellular damage of the liver cells. The common test that form part of the liver function test profile are the serum Bilirubin, Total serum proteins and albumin globulin ratio, liver enzymes and prothrombin time. In all these tests, we shall talk about the liver enzymes (ALT) AST, and ALP) and the Bilirubin.

 1.4.4 Liver Marker Enzymes

The liver marker enzymes include the

• Transaminases which are the Alanine Amino transferase (ALT), Aspartate Amino Transferase (AST) and Alkaline phosphatase (ALP).
• Bilirubin which include Total and conjugated bilrubin.

1.4.5 Transminases

AST (SGOT-serum glutamic oxaloacetic transamnase

ALT (SGPT-serum glutamate-pyruvate transaminase the amino group from an amino acid to q ketoacid converting the q keto acid. The transaminases that are measured in the liver function test are ALT (SGPT) and AST (SGOT).

Alanine  Transaminase (ALT) catalyse the following reaction.

Alanine + a-ketoglutarate           Pyruvate + Glutamate

Aspartate amino transaminase (AST) catalyzes the following reaction.

Aspartate+ a-ketoglutarate            oxaloacetate + Glutamate

The Normal level of ALT in serum is 7 to 40111/L. The Normal level of AST in serum is 8 to 4011/L. An increase in AST or ALT levels hints at an insult to the liver parenchyma tissue. ALT is a more specific marker of hepatic injury than AST as AST elevation is also muscle tissue. To measure the level of transaminases the reaction catalyzed by them is coupled to a reaction in which NADH is used up resulting in change in the photometric intensity when read in the UV range at 340nm. It is a UV kinetic method for ALT (SGPT)

Alanine + a-ketoglutarate           Pyruvate + Glutamate

Pyruvate + NADH +H⁺lactate + NAD⁺

For AST (SGOT):

Aspartate+ a-ketoglutarate            oxaloacetate + Glutamate

Oxaloacetate + NAPH +H⁺Malate + NAD⁺

1.4.6 Alkaline phosphatase

It is a hydrolase that removes phosphate from all kinds of molecules such as proteins, nucleotides, etc. It is found in cells living the billiary system hence a rise in it level is indicative of damage to the billary tree due to cholestasis. It may be due to stone blocking the large ducts or intraphepatic obstruction, inflammation of the billiary channels. Alkaline phosphatase is also found in placenta and bones. Hence the level is also increased in growing children in whom bones undergo remodeling and in paget’s disease in adults. Normal level of alkaline phosphatase is between 45 to 115 IU/L. The method for measuring the level of alkaline phosphatase is a kinetic method using p-nitrophenylphosphate as substrate for the enzyme and measuring rate of formation of the coloured substrate (p-nitrophenol) formed from the reaction. This measurement of the color intensity is done calorimetrically at a wavelength of 405nm.

P-nitrophenylphosphate + H20        p-nitrophenol + Phosphate.

1.4.7 Serum Bilirubin

Bilirubin is an orange yellow pigment a waste product primarily produced by the normal breakdown of home. Heme  is a component of hemoglobin, which is found in red blood cells (RBCs). Bilirubin is ultimately processed by the liver to allow its elimination from the body. This test measures the amount of bilirubin in the blood to evaluate a person’s liver function or to help diagnose anemias caused by RBC destruction (helmolytic anemia). The bilirubin test are the conjugated  and total bilirubin test. The conjugated bilirubin is a water soluble from of bilirubin formed in the liver by the chemical addition of sugar molecules to unconjugated bilirubin; when present in the blood, conjugated bilirubin can become chemically bound to albumin forming delta-bilirubin (also known as biliprotein) Both the total and conjugated bilirubin tests are blood test that measure the amount of a substance called bilirubin. They are used to find out how well the liver is functioning.

1.5Origin of Monosodium Glutamate (MSG)

Asians had originally used the “kombi” seaweed’s broth as a flavor enhance without understanding that glutamic acid was its flavor enhancing component. MSG was discovered by a Japanese professor, kikunae Ikeda, in 1908. He isolated a white substance in seaweed to flavours his food and found out later on that the substance is h-glutamate. Since ikeda found MSG in seaweed, the very first raw materials of MSG is seaweed. However MSG was found in many other ingredients such as tomatoes, fish and yeast. Glutamic acid was discovered and identified in 1866 by the German chemist karl Heinrich Rithausen who treated wheat glutein with sulfuric acid. (R.H.A. Phimmer, 1912) Kikuna Ikeda of Tokyo imperial university isolated glutamic acid as a taste substance in 1908 from the seaweed 9aminania Japonica (Kombu) by aqueous extraction and crystallization calling its taste Umami (Lindemann, et al., 2002). The Japanese broth of latsuobushi and kombu had a unique taste not yet scientifically described (not sweet, salty, sour or bitter). To verify that lonized glutamate was responsible for Umami, he studied the taste properties of glutamate salts, calcium, potassium, ammonium and magnesium glutamate. All these salts elicited Umami and a metallic taste due to other minerals of them, sodium glutamate was the most soluble, most palatable and easiest to crystallize. Ikeda called his product monosodium      glutamate and submitted a patient to produce MSG (Ikeda K 1908) the Susuki brothers began commercial production of MSG in 1909 as Aji-No- moto (Sano et al., 2009).

1.5.1 Chemical and Physical Properties of Monosodium Glutamate

The molecular formula of monosodium glutamate is C₅ H₈ NNaO4 and its molar mass is 169.11gmol^-1. Monosodium glutamate has the same basic structure of amino acids with an amine group (-NH2) and carboxylate ion instead the carboxylic group (-coo-). Moreover MSG has other carboxylic group in the side chain. Its chemical structure can be written as below, in the common representations used forMonosodium glutamate.

Figure1.3: Structure of monosodium glutamate

Physical Properties: MSG is a white crystalline powder with a slightly peptone like odor. Its melting pointing is 232OC and it is highly soluble in water. Its insoluble in common organic solvents. MSG is used to impart the Umami (Meat-like) taste to food.

Chemical Properties: MSGis very stable to high temperatures, thus it can be used in industrial food-processing conditions. It is important noting, glutamic acid has two carboxylic groups in its structure but MSG corresponds to the deprotonation of the  – carboxylic group, which has the most acidic hydrogen. The compound is usually available as the monohydrate. The solid contains separate sodium cations Na+ and glutamate anions in Zwitterionic form, -OOC-CH (NH₃⁺)-(CH₂)2-(OO). In solution it dissociate into glutamate and sodium ions. (Chiaki, et al., 1989).

1.5.2 Uses and Utility of Monosodium Glutamate

        MSG is used to give “meaty” “savoury” or “brothy” taste to foods by stimulating the glutamate receptors on the tongue. There are glutamate receptors in other parts of the body, notably the brain, where glutamate is neurotransmitter.

Flavours probably exert their effect by increasing the number of molecules that interact with receptor on chemosensory membranes in the nose and oral cavity. This intensification of chemosensory stimulation induces more salivation, produces grater stimulation of the of factory and limbic system of the brain and promote immune function (Schiffman 2000).

MSG (with or without 5’-ribonucleotides) likely exerts effect by adding another taste quality to food that is Umami, which improlles palatability (Bellisle et al.,1991). Neither MSG nor 5’-ribonucleotides appear to exert their effect by altering the perceived intensity of other component of food or altered the intensities of salts; sweeteners, amino acids or bitter compounds (Schiffman, 2000).

However, free glutamate as found in soy sauce or prepared foods, enters the blood stream much faster than the glutamates slowly during digestion (Loliger, 2000). Knowing the beneficial contribution of glutamate to many savoury flavours, it is not at all surprising that industrial processes take advantage of the rather high natural glutamate concentrations of some vegetables in the production of vegetable protein hydrolysates. These hydrolysates contain considerable amounts of free glutamic acid (sodium glutamate e.g. traditional say sauce (Loliger, 2000). Today say sauce is the product of thousands of years of development. This age old discovery is understood today and it is used to enhance the pleasure of eating industrially processed food (Loliger, 2000).

1.5.3 Monosodium glutamate production

Some foods naturally have monosodium glutamate such as, cheese and tomatoes. In The early 1900s, MSG was extracted from rich protein foods such as seaweed. Today MSG is made from corn starch, sugarcane, sugar beets or molasses (George, 2004). MSG is made by a natural method that has been used for over centuries. This is known as the fermentation process. It is similar to how wine, beet, vinegar and yogurt are made MSG is usually found in Aisan corner stores. The packaging is white and red with monosodium Glutamate in red big letters and Chinese lettering.

MSG is made up of different raw materials. It is made up of the most commonly use bacteria called corynebacterium glutamicu previously known as micrococcus glutamicum (George, 2004). Glutamate is a very popular bacterium that is used in other amino acids. The producers prefer sugar cane of beet molasses, starch hydrolystates from corn or cassava tubers, and even tapioca. The first sugar source available is the first to be used with sugar; ammonia and ammonium slats are added. To finish off the process vitamins and other nutriments are included. MSG is also manufactured by a fermentation process where in bacteria are grown aerobically in a liquid nutrient medium. The bacteria release glutemaic acid as a bye product of metabolism into the liquid nutrient medium in which they are grown. The glutamic acid is then separated from the fermentation broth by filtration, concentration, acidification and crystallization and conversion to its sodium salt. The name monosodium glutamate  refers to a 99% pure combination of glutamic acid and sodium (George, 2004).

Figure 1.4: This is a picture showing MSG fermentation production

1.5.4 Benefits Monosodium Glutamate    

• Flavour: MSG brings out the flavour of savory dishes. According to the European food information council or EUFIC, it’s also added to processed foods, frozen foods, canned soups and broths, salad dressing and spice mixes. MGS also goes by the names hydrolyzed soy protein and autolyzed yeast. It adds a “fifth flavor” to food called “Umami”. The taste MGS imparts to food has been described using many positives adjectives: meaty, hearty, rounded, savory and “broth- like”.
• Sodium Reduction: MSG can replace other sodium heavy seasonings in food. MSG has one third the amount of sodium that table slat does cooks who use this additive to flavor dishes can decrease the amount of table salt they use by up to 40 percent and the dish will still taste good.
• Safety:Monosodiumglutamate has hundreds of studies to support its safety, according to the international food information council foundation, IFICF. Some of the following governmental authorities and use as a food additive: the V.S Food and Drug Administration; the National academy of sciences; the European community’s scientific committee for food; and the American Medical Association (Lisa, 2017).

1.5.5 Medical Effects of MSG

Although MSG helps our food taste better a large amount of it can be harmful to our health. In 1968, the risks of MSG were first reported. its symptoms includes, Headache, flushing, sweating, facial pressure or tightness, Numbness or burning in the face, neck and other areas, repaid fluthering heart beats, chest pain and Nausea (Zeratky, et al., 2012). However researchers have found no definitive evidence of a link between MSG. Symptoms are usually mild and don’t require treatment. The only way to prevent a reaction is to avoid foods containing MSG (Katherine, 2018). A hypothetical MSG symptom complex is called the “Chinese restaurant syndrome (Kwok’s Disease).

1.5.6 Effects of Monosodium Glutamate in Liver

Although most of the body tissues are affected by MSG but liver as chief metabolic centre have been main targets of researchers after central nervous system. Hamaoka and kusunoki studied the growth pattern of visceral organs in monosodium L-glutamate treated obese mice having hypothalamic lession. After subcutaneous injections of MGS (2mg/g.b.w for 5 days) to neonatal mice they found reduction of the weight of kidney, heart and tastes while  they observed weight of liver to be low up to 12 weeks and identical with control mice thereafter which they attributed to occurrence of fatty change in a hypoplastic liver (Hamaoka et al., 1986). Malik et al., (1994) observed significant increase in content of total lipids, phospholipids, triglycerides and free fatty acids in liver of adult male mice 31 days after the last injection of MSG (2mg.  4mg and 8mg/g of b.w. for 6 days). They also observed shifting of carbohydrate metabolism towards lipogenesis leading to hyperlipidemia  (Malik, et al., 1994) Yoshida et al., found that  MSG treated (2mg/g b.w.8c) mice became obese 9 weeks after birth and were found with higher blood levels of glucose, total  cholesterol, HOL- cholesterol, GPT and cholinesterase along with greater triglyceride content of liver relative to control mice. They noted marked fatty change in liver of MSG obese mice. In another set of “MSG obese mice “They observed that high fat diet with probucol for 2 weeks significantly reduced the development of fatty liver (Yoshida, et al., 1995).1.6 Justification of Study

Monosoium glutamate (MSG) is a food additive used as flavour enhancer for variety o Nigerian meals as well as delicacies from other parts of the world. Different market brands of MSG serve to improve the palatability of meals and as such stimulate and enhance appetite. Reports of the food and Drug Administration (FDA) of the United  States noted that MSg is safe and should be considered as Generally Recognized as safe food additive, which is often consumed without specific requisite upper limit to average daily intake. MSG induced with vitamin e on diabetic rats causes oxidative stress and hepattoxicity in albino rats. The present study investigated the capacity of mixture of MSG and tocopherol (Vitamin E)  to induced oxidative stress in the hepatic functions of Albino wistar rats.

1.6.1 Aim OF STUDY

        The aim of this work is to evaluate the possible effect of MSG and -tocopherol on the hepatic tissues (Liver) of wistar rats.

1.6.2 Objectives of the study

• The effect of MSG, and -tocopherol on Aspartate amino transferase concentration of rat.
• The effect of MSg,and -tocopherol on Alamine amino transferase concentration of rat.
• The effect of MSG and -tocopherol Alkaline phosphatase concentration of wistar rat.
• The effect of MSG and -tocopherol Bilirubin concentration on wistar rat.
• To determine the changes in blood glucose in rats treated wit MSG and -tocoppherol.

Pages:  106

Category: Project

Format:  Word & PDF

Chapters: 1-4

Material contains Table of Content, Abstract and References