Assessment of the Defense System in Diabetic Rats Treated With Aqueous Leaves Extract of Terminalia catappa
Chapter One
AIM OF THE STUDY
Considering the development of diabetes mellitus to be immune system related, it become of interest to find out what could be the possible state of the body’s defense system comparatively in diabetic and non-diabetic conditions.
CHAPTER TWO
LITERATURE REVIEW
Diabetes
The word diabetes originates from a Greek word “siphon”. Aretus the Cappadocian described the condition known as diabainein – passing too much water (polyuria). Thomas Willis added mellitus to the term in 1675, drawing reference from the term “Mel” which means “honey” in Latin. Taking cognizance of the fact that the blood and urine of diabetic individuals have excess glucose, DM could literally be taken to mean “siphoning off sweet water”. The term “Sweet Urine Disease” was coined when ants were observed to be attracted to some individuals’ urine, because of high glucose content in the urine (Mandal, 2012). Diabetes is associated with the destruction of pancreatic β-cells which consequently leads to insulin deficiency resulting in insulin resistance (American Diabetes Association, 2010).
Diabetes is characterised by chronic hyperglycemia, a very common metabolic abnormality among diabetic individuals inducing increased ROS generation which leads to oxidative stress (Evans et al., 2002). Hyperglycemia is associated with failure of various organs; the liver, eyes, kidneys, blood vessels, nerves, heart, and damage to macromolecules (Dutta et al., 2008). Hyperglycemia causes oxidative stress via several mechanisms leading to a rise in the generation of advanced glycated end products (AGEs), formation of superoxide radical, as well as increase in protein glycosylation, inflammatory mediators and glucose autoxidation (Garay-Sevilla et al., 2005).
- Consequently, when overproduction of ROS occurs, this surpasses the antioxidant system’s capacity to counterbalance and eliminate these species, subsequently resulting in oxidative stress (Rahman et al., 2012). The oxidative stress in the diabetic state is due to autoxidation of glucose level which usually leads to free radical generation and disruption of cellular homeostasis (Khan et al., 2015).
TYPES OF DIABETES
The three main types of diabetes are:
- Type 1 diabetes, also known as juvenile onset or insulin-dependent diabetes mellitus (IDDM).
- Type II diabetes, also known as adult-onset or non insulin-dependent diabetes diabetes mellitus (NIDDM).
- Gestational diabetes.
TYPE I DIABETES MELLITUS
This usually occurs in children and young adults and is considered an autoimmune. An autoimmune disease results when the body’s system for fighting infection turns against a part of the body. In type 1 diabetes, the immune system attacks the insulin-producing beta cell in the pancreas and destroys them. The pancreas then produces little or non insulin, thereby preventing cells from taking up sugar from blood.
Someone with type 1 diabetes needs daily injections of insulin to live. The person also needs to follow a strict diet and monitor her blood sugar levels. Symptoms include increased thirst and urination, constant hunger, weight loss, blurred vision, and extreme tiredness. If not diagnosed and treated with insulin, the person can lapse into a life threatening coma.
CHAPTER THREE
MATERIALS AND METHODS
Materials:
1-Chloro-2,4-Dinitrobenzene (CDNB)
Phosphate buffer
Dipotassium hydrogen orthphosphate (K2HPO4)
Distilled water
Trichloroacetic buffer (TCA)
Ellman’s reagent
Sodium citrate
Sodium azide (NaN3)
Hydrogen peroxide
Serum
Ethanol
GST assay kit
GSH assay kit
GPX assay kit
EQUIPMENTS:
Centrifuge
Spectrophotometer
Beakers
Test tubes
Micropipette
Burette
Weighing balance
Stop watch
Determination of Glutathione S-Transferase (GST) Activity Assay
Principle:
Glutathione -S-Transferase (GST) has a notable activity when 1-chloro-2,4-dinitrobenzene (CDNB) is added and thus increases its wavelength making it easy to measure its enzymatic activity.
Procedure:
0.03ml of phosphate buffer was introduced to the blank and 0.03ml of the homogenate to the tests. 0.03ml of 0.1M of Reduced glutathione, 0.1 5ml of CDNB, followed by the addition of 2.79ml of 0.1M phosphate buffer was added to both the blank and the test test-tubes. The reaction was allowed to run for 60 seconds each time before the absorbance was read against the blank at 340nm. The temperature was maintained at approximately 31oC. The absorbance was measured (Habig et al., 1974).
CHAPTER FOUR
RESULTS
Table 4.1: Weight of Rats Before and After Induction with Aqueous Terminalia Catappa Leaf Extracts.
From the table below, it is seen that there is a significant increase (P< 0.05) in the weights of the rats upon induction of the rats with aqueous Terminalia Catappa leaf extracts.
CHAPTER FIVE
DISCUSSION AND CONCLUSION
DISCUSSION
Free radicals are constantly formed in living cells and removed by antioxidant defenses. Antioxidant enzymes are the main line of defense against free radicals in animal and plant cells. Uncontrolled generation ROS are involved in a number of human disease states, including diabetes and cancer due to disturbance in cellular and molecular processes (Praveen and Ashish, 2012). Glutathione S-transferase (GST), Glutathione reductase (GSH) and Glutathione peroxidase (GPx) are part of the most common antioxidant enzyme and they can be applied as marker enzymes especially in detection of liver disease cases.
The effect of aqueous Terminalia Catappa leaves extract on the redox status of the cellular system of alloxan-induced diabetic wistar rat was examined in this study. Results showed that there was no significant difference (p> 0.05) in the GST activities of the control group and the treatment group while a significant difference (p< 0.05) was recorded in the GPx and GSH activities of the control and treatment group.
GST play a primary role in detoxifying xenobiotics. The result of this study showed that although there was no significant change (p> 0.05) in the activity of GST in both control (3.338±1.33) and treatment groups (2.521±0.080). The GST activity of the treatment group was very close to that of the control which indicates that the aqueous leaf extract of Terminalia Catappa had a positive effect on the GST activity of the diabetic rats.
GSH is a major non-protein thiol in living organisms which plays a central role in coordinating the body’s antioxidant defence processes. Perturbation of GSH status of a biological system has been reported to lead to serious consequences (Uday et al., 1999). The GSH status of the treatment group (1.073±0.519) was significantly lower (P> 0.05) than that of the control group (8.334±8.642). This also indicates that the aqueous leaf extract of Terminalia Catappa had no positive effect on the GSH activity of the diabetic rats.
GPx is a seleno-enzyme two third of which (in liver) is present in the cytosol and one third in the mitochondria. In hyperglycemia, glucose undergoes auto-oxidation and produces superoxide and it produces free radical that in turn leads to lipid peroxidation in lipoproteins. GPx catalyzes the reaction of hydroperoxides with reduced glutathione to form glutathione disulphide (GSSG) and the reduction product of the hydroperoxide. In this present study, the GPx activity of the treatment group (2.932±1.830) was significantly lower than that of the control group (13.056±3.934). This clearly indicates that the use of aqueous Terminalia Catappa leaf extract in diabetic rats had no positive effect on the GPx activity of the rats.
The result of this present study is not in line with those reported in other literary works on medicinal plants (Shajeela et al., 2013; Comfort et al., 2017) which showed improvement in the levels of antioxidant enzymes upon treatment with the medicinal plants. The difference may be due to difference in medicinal plant species as well as method of preparation.
CONCLUSION
In conclusion, aqueous leaf extract of Terminalia Catappa has no positive effect on the redox status of the cellular system of alloxan-induced diabetic wistar rat.
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