Strength and independence of associations between ghrelin, leptin, adiponectin and insulin in stimulating basic functions to energy metabolism

Background: The effect of diet composition on the fat regulating hormones and its possible interaction with insulin is necessary to fully understand the mechanisms by which the body controls feed intake. Objective: The objective of this work was to evaluate the relationship between ghrelin, leptin, adiponectin and insulin with respect to diet composition. Fasting and refeeding represent a natural challenge for stimulating basic functions to energy metabolism. Methods: The present study was conducted on 40male albino rats that were divided into 4 groups (n=10): (I): fed ad/libitum, (II): fasted group, refed group allowed for 20 min refeeding with food stuffs divided into two groups, (III): carbohydratemeal, (IV): fat meal. The present study suggests a physiological interaction of ghrelin and leptin in the periphery. Elevated fasting ghrelin appears tomodulate other hormonal systems that participate in the regulation of food intake. Ghrelin inhibition after feeding is related to different nutrients satiating capacity. In addition to feeding, several hormonal states have also been involved in the suppression of postprandial ghrelin production. Meal and insulin were found to acutely affect leptin concentration. Inverse change in ghrelin and leptin between fasting and refeeding state may indicate a role of gastric leptin in regulating ghrelin secretion. Positive correlation between adiponectin and insulin with both macronutrients suggests a role of adiponectin in enhancing insulin action. The fact that gastric leptin is stimulated by diet and ghrelin responses could be due to direct effects of multiple hormonal signals which require postgastric feed back on the stomach among the latters (glucose and insulin).