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ESTIMATION OF SERUM LLIPIDS (TOTAL CHOLESTEROL, HDL � CHOLESTEROL AND LDL � CHOLESTEROL IN ALLOXAN INDUCED DIABETIC WISTER RATS

ABSTRACT

This research work assessed the hypoglycaemic effect of canavaelia ensiforoms and its relationship with serum lipids (total cholesterol, HDL – cholesterol and LDL – cholesterol) in an alloxan induced diabetic rat. Diabetes was induced using 100mg/kg during weight of a 5% stock solution of alloxan. Three were four groups and they were divided into group treated with 200mg/kg body weight of the plant extract, group treated with 400mg/kg body weight of the plant extract, diabetic control group and normal control group. The result after 14 days of treatment with the plant extract showed significant reduction in blood glucose concentration in diabetic rat treated with 200mg/kg of plant extract (94.5 + 25.22mg/dl) as compared to the diabetic control rats (38016 + 133.01mg/dl). The effect of the plant extract an serum total cholesterol in diabetic treated rats with 200mg/kg body of (ensiforms also decreased significantly (118.20 + 24.55mg/dl) is compared to the diabetic control rats (201.84 + 61.55mg/dL). In addition, there was significant increase in the HDL – cholesterol of the diabetic rat treated with 200mg/kg body weight of the plant extract (57.54 + 16.31mg/dL) as compared to the diabetical rat (3286 + 7.42mg/dL). Finding, there was significant reduction in the LDL – cholesterol of the diabetic rat treated with 200mg/kg body weight of the plant extract (51.59 + 29.82mg/dL) as compared to the diabetic control (133.44 + 57.39mg/dL). Thus, canavalin ensiform extract reduces blood glucose, total cholesterol, LDL – cholesterol and increase HDL – cholesterol. 

INTRODUCTION

LITERATURE REVIEW

The use of dietary legumes have been reported to influence glycoami and lipiddaemia in man and experimental animals. (Mahnow et l. 1980; Bingwem et al., 1981, Molgaard et l. 1987; Donatucei et al. 1987). (anaralis ensiformis DC (family: leguminosaae) variously known as jack beans, though a nature of central America and west idnies has been widely cultivated in the Lumed tropics of Africa and Asia. The seeds have been reported to possess antihypercholesterolaemic (Marfo et al., 1990) and hypoglycemic (enyikwola et al., 1991) activities. Diabetics mellitus is a syndrome characterizing by chronic hyperglycemic and disturbances of carbohydrate, fat and protein metabolism associated with absolute or relative deficiencies in insulin secretion and/or insulin action (Bennet, 1994). Patients, with this disease are generally classified as either type I (insulin dependent) or type 2 (non – insulin and dependent) diabetics. For oth types of diabetes, control of blood glucose levels, lipids leels,blood pressure and weight will reduce the rise of vascular problems and associated diseases (Williams, 1994). Earlier work on the effect of (ensiforms on normal and alloxan induced diabetic rats showed statistically significant decreases in blood and arising urinary glucose weight loss to the treated diabetic animals (Nimen bo – Uadia and Osagie, 1999). This study reports the effect of C. ensiforms on total senior cholesterol, HSL – cholesterol and LDL – cholesterol in alloxan – induced diabetic rats. 

CHOLESTEROL

Cholesterol is the most common lipid because of the strong correlation between high levels of cholesterol in the blood and the incidence of human cardiovascular diseases. Basic research on cholesterol has led to thousands of experiments and helped uncover the key role this compound plays in the development of heart diseases. Fortunately, it also led to the discovery of another group of molecules I know as stains which greatly lower the amount of cholesterol cruising the blood. Clinical studies revel that statins lower the risk of heart disease by as s much as 40% and help explains, along with other now treatment and prevention strategic, why the number of deaths disease has been slashed by close to 60% since 1950 (Thompson, 2001). Cholesterol is a type of lipid and lipid and water don’t mix. Cholesterol has to be encased is a water friendly structure called a lipoprotein to be easily transported in the watery avenue of blood that traverse the body (Olson, 988). Due to their varied densities different types of lipoproteins carrying cholesterol in the blood have been discovered after ultracentrifugation. 

The different type of lipoprotein include chylomicrons (CM), very – low – density lipoproteins (VLDL), low – density lipoprotein (LDL) and high density lipoproteins (HDL) fielding and Fielding, 2008). Elevated blood levels of cholesterol carried in low density lipoproteins (LDL) were linked to a high cholesterol diet and heightened risk of atherosclerosis. Cholesterol carried in high density lipoprotein (HDL) was not linked to atherosclerosis at all, but rather seemed to protect against the disease. It wasn’t the total level of cholesterol in the blood that was so important for coronary heart disease, but rather how the cholesterol was distributed among the different particles that can carry it in the blood stream. It is now generally understood that the first step in the development of heart disease is an excess LDL cholesterol traveling in the blood. This excess, which could be diet induced or could stem from a genetic tendency, makes it more likely that some of the LDL cholesterol from the blood will slip in between the cells that compare the inner w alls of arteries. Not easily broken down, the LDL cholesterol remains lodged in between these cells, causing a local initiation. To deal with this irritating intruder, the garbage eating cells of the immune system (macrophages) are drawn to the cholesterol lodged in the artery and ingest it. Eventually the macrophage die, spilling their cholesterol contents into the arterial wall. This cholesterols combined with the intact cholesterol engaged macrophages, and form the fatty streaks in the arteries (Brown and Goldstein, 1984). 

BLOOD CHOLESTEROL CAN BE LOWERED OF RESIN AND STATIN DRUGS

Lesisni commonly used cholesterol – lowering drugs work by preventing the reabsorption and subsequent recycling of bile acids to acid digestion. To make new bile acids, the lower increases its production of B – hydroxyl – B – methylglutayl – COA (HMG – COA) reductase the enzymatic trigger for cholesterol production. It also gather cholesterol from the blood stream by slightly boosting its production of LDL receptors on its cells. Statins, by contrast, limit cells production of cholesterol by directly inhibiting B – hydroxyl – B – methylglutayul – COA (HMG – COA) reductase. This prompt cells to gather more cholesterol from the blood by making substantially more LDL receptors. The end result is more effective lowering of blood LDL cholesterol level (Brown and Godlstein, 1984).

BIOSYNTHESIS OF CHOLESTEROL

Cholesterol, like long chain fatty acids, is made from acetyl COA. Synthesis takes place in forms stages. Condensation of two molecules of acetyl/COA to form acetoacetyil – COA which condenses with a third molecule of acetyl – COA to yield the six – carbon compound, B – hydroxyl – B – methylglutary/COA (HMG COA). These first two reactions are catalysed by thiolase and HMG – COA syntheses respectively. The third reaction is the committed and rate limiting step reduction of HMG – COA to meralonate for which each of two molecules of NADPH donates two electrons. This reaction is catalyzed by HMG – COA reductase. HMG – CoA reductase, an integral membrane protein of the smooth endoplasmic reticulum is the major par to regulation on the pathway to cholesterol biosynthesis. Conversion of meralonate to activated isoprene units Polymerization of six 5 – carbon isoprene units to form the 30 – carbon linear squalene. Cyclization of squalene to form the four rings of the steroid nucleus, with a further series of changes (oxidation, removal or migration of methyl groups) to produce cholesterol( Edward and Ericson, 1999).

3 acetate

Mevalonate

Activated isoprene

Squalene

Cholesterol.

LOW DENSITY LIPOPROTEIN (LDL) AND CHOLESTEROL METABOLISM

LDL are the main carriers of cholesterol of the adrenals and adipose tissue where there are receptors apo B – 100 that are able to take in the LDL by a similar process to that occurring in liver (Hevenoja et al, 2000). Within there tissues, the cholesterol esters are hydrolysed to yiled free cholesterol which is in corporate into the plasma membranes as required. Any excess cholesterol is re-esterifies by an acyl-COA cholesterol acyltransferse for intracellular storage. Other peripheral tissues have much lower requirements for cholesterol, but that delivered by LDL may be helpful in suppressing synthesis of cholesterol denovo within cells. It may also inhibit the expression of lipoprotein receptors (Rodenburg and Vander Horts, 2005).

Cholesterol is essential to provide hydrophobility to the VLDL so that they can carry tricylglycerols efficiently in the aqueous environment of plasma. However, once this has been accomplished the cholesterol rich, triacylglycerol – depleted remnant LDL by – products are potentially toxic and must be safely reward from circulation. A significant part of the complexity of lipoprotein metabolism is concerned with the disposed of this LDL cholesterol before it can cause damage to cardiovascular system (Oloifsson and Boren, 2005). Increase LDL particle accelerate the development of diabetes mellitus.

HIGH DENSITY LIPOPROTEIN (HDL) AND CHOLESTEROL METABOLISM

HDL are the most complicated and diverse of the lipoproteins, as they contain many different protein constituent, whose main purpose is to enable secretion of cholesterol from cells, esterification of cholesterol inplasam, transfer of cholesterol to other lipoproteins, and the return of cholesterol to the live for excretion – a process that has been termed ‘reverse cholesterol transport’ (brown, 2007). In addition, they have an important function in traicylglycerol transport by facilitating the activation of lipoprotein lipase, in the transfer of triacylglycerols between lipoprotein classes, and in the removal of chylomicron remnants and VLDL enriched in triacylglycerols (Gordon et al, 2011).

It requires apo A1 for activation (Davidson and Thompson, 2007). HDL also contains apo C11, apo CII as well as the enzyme lecithin – cholesterol acyltransferase (LCAT), which catalyses the formation of cholesterol esters from lecithin (phosphaditylhcoline) and cholesterol and phosphatidylcholine (newly forming) HDL particles converts the cholesterol and phosphatidylcholine of chylomicron and VLDL remnants to cholesteryl esters which begin to form a core, transforming the disk shaped nascent HDL to a mature spherical HDL particle. This cholesterol rich lipoprotein the returns to the liver, where the cholesterol is unloaded, some of the cholesterol is converted to bile salts (Russell, 2003). Decreased levels have been food in association with diabetes mellitus

ALLOXAN

Alloxan (2,4,5,6 – tetraoypyrimidinetetrone) is an oxygenated of pyrimidine derivative. It is present as alloxan hydrate in aqueous solution.

BIOLOGICAL EFFECT OF ALLOXAN

Alloxan is a toxic substance which basically destroys insulin – producing cells in the pancreas when administered to rat and many other animal species. This cause an insulin dependent diabetes mellitus (called Alloxan diabetes) in the animals, with characteristic similarity to type1 diabetic is preferentially accumulate in beta cells through uptake via GLUT 2 glucose transporter. Alloxan in the presence of intracellular thiols, generates reactive oxygen species (ROS) in cyclic reaction with its reduction product, dialuric acid (Mroziklewicz et al., 1994).

SYNTHESIS

The original preparation for alloxan was by oxidation of uric acid. In another method, the monohydrate is prepared by oxidation of barbituric cid by chromatin trioxide (Holmgreen et al, 1963). Alloxan is a strong oxidizing agent and forms a hemiacetal with its reduced reaction products, dialuric acid which is called alloxatin.

IMPACT UPON BETA CELLS

Because it selecting kills the insulin producing beta – cells found in pancreas, alloxan is used to induce diabetes in laboratory animals. This occur most likely because of selective uptake of the compound due to its structural similarity to glucose as well as the beta – cells highly efficient uptake mechanism (glutz) However, alloxan in not toxic to human beta – cells, even in very high doses, probably due to differing glucose uptake mechanism inhuman of rats (Tytrberg et al., 2001, and Eizirik et al,. 1994).

DIABETES MELITUS

Diabetes mellitus is metabolic disorder characterized byihyperglycemia and insufficiency of secretion or action of exogenous insulin. This hyperylycemia is often accompanied by glycosuria, polydipsia and polyuria. Ll fors fo diabetes are due to the beta – cells of the pancreas being unable to produce sufficient insulin to prevent hyperglycemia (rotter, 2007) In type I diabetes mellities or insulin-department diabetes mellities (IDDM) , the disease begins early in life and quickly become severse. This disease responde to insulin injection , because the nvetabolic defect stems from a paucity of pancreatic B cells and a consequent inability to produce sufficient insulin. Type II diabetes melletis or non-insulin-dependent diabetes mellitus (NIDDM) also called insulin-reristant diabetes is slow to develop and the sy,mtpon are miller and often go unrecognized at frist. In this type of diabete, theregulatory activity of insulin is defective: insulin is produced, but some featured of the insulin-response system is defective.

Individuals with either type of diabetes are unable to take up glucose efficiently from the blood. Insulin triggers the movement of GLUT4 glucose transporters to the plasma membrane of muscle and adipose tissue. Another characteristic metabolic change in diabetes in excessive but incomplete oxidation of fatty acids in the liver (altomore et al: 1992). The acety can produced by B-oxidation cannot be completely oxidized by the citric acid cycle because the high (NAOH)/(NAD+) ratio produced by B-oxidation inhibits the cycle. 

Accumulation of acety-cott leads to production of the ketone bodies acetoacetate and B-hydroxy butyrate, which cannot be used by extrahepatic tissues as fast as they are made in the liver. In addition to B-hydroxybutyrate and acetocetate, the blood of diabetes also contain acetone which results from the spontaneous decarboxylation of acetoacetate. Diabetes mellitus can cause viral infection, autoimmune disease, numerous complications affecting the vascular system, kidney, retira, lens, peripheral nerves and skin (Gafvels et al, 1993).

Diabetes produced disturbances of lipid profiles, especially an increased susceptibility of lipid proxidation, which is responsible for increased incidence of atherosderosis, a major complication of diabetes mellitus. During diabetes, persistent hyperglycemia causes increased production of free radicals especially reactive oxidative species from all tissues from glucose autoxidation and protein glycosulation. Diabetes mellitus is a useful model illness for considering the effect of chronic disease on health related quality of life. Studies have shown variability in the quality of life effects of type I and type II diabetes. For example, Grafvels found that patients with diabetes mellitus more frequently have alone and remained childless, participated in fever social activities. A recent study has demonstrated that early and aggressive intensive therapy leading to improved glycaenic control is likely to reduced the impact of diabetes mellitus health-related quality of life by slowing the onsets and progression of complications.

1.7 SIGNS AND SYMPTOMS OF DIABETES MELLITUS

Fatique

Increased unrination (polyuna)

High rates of body weight loss.

Increased thirst and fluid intake (polydipsia)

Blurred vision

Mental confusion

Increased hunger.

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