Effects of Fat and Cinnamon Feeding on Adiponectin after Rat Injection with Dexamethasone

Abstract

Chronically excessive numbers of glucocorticoids are known to induce insulin resistance, which is possibly involved in impairing the insulin signaling in liver, muscle, and adipose tissues. Excessive levels of cortisol are characterized by the symptoms of abdominal obesity, hypertension, glucose intolerance or diabetes and dyslipidemia ,all of these features are shared by the condition of insulin resistance .Consumption of high levels of dietary fat is thought to be a major factor in the promotion of obesity and insulin resistance [7]. Fatty acid composition in the diet is another mechanism implicated in the development of insulin resistance [6]. Several environmental factors, including high-fat diet, are reported to activate the functioning of the hypothalamus-pituitary-adrenal axis [HPA]. Frequently evoked HPA-axis secretes excessive amount of cortisol [21] and elevated cortisol level is implicated in the development of entire spectrum of the metabolic syndrome, including insulin resistance, visceral obesity and dyslipidemia as well as the kinds of [21]. Cinnamon contains biologically active substances that have demonstrated insulin-mimetic properties. In vitro [3] and in vivo [1, 20] studies have shown that cinnamon enhances glucose uptake by activating insulin receptor kinase activity, autophosphorylation of the insulin receptor, and glycogen synthase activity. Other recent studies have demonstrated the ability of cinnamon to reduce lipid levels in fructose-fed rats, potentially via inhibiting hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity [2]. Adiponectin is the most abundant plasma protein synthesized for the most part in adipose tissue, and it is an insulin-sensitive hormone,playing a central role in glucose and lipid metabolism [7] Furthermore, adiponectin levels are inversely associated with visceral adiposity [15]. Moreover, adiponectin has been reported to exhibit anti-atherosclerotic and anti-inflammatory effects [17,16].