Relation between Plasma Levels of Ghrelin and Hyperphagia in Streptozotocin-Induced Diabetes in Male Albino Rats
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Relation between Plasma Levels of Ghrelin and Hyperphagia in Streptozotocin-Induced Diabetes in Male Albino Rats,MAHA M. SABRY, YASER M. ASHOUR, LAILA A. EL SAYED and ISSAM O.A. EL-MARAGHY
Abstract
Background: Ghrelin, a hormone identified in the stomach, is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R) and the peripheral or central administration of ghrelin increases food intake and body weight. Ghrelin release and gene expression are regulated by nutrient flux, such that plasma ghrelin levels increase steadily before meal onset and fall rapidly after food ingestion. Some studies have suggested that tonic vagal activity may play a role in main-taining baseline plasma ghrelin level or may cause increase in the plasma ghrelin level in case of food deprivation.
Material and Methods: 72 normal adult male albino rats were divided into three groups 24 rats each. Group (I): Control group (n=24), Group (II): Induced diabetic group (n=24) and Group (III): Induced diabetic group treated with insulin (n=24). Each of these groups was divided into three subgroups 8 rats each. Group (a): Injected with saline IP once daily throughout the experimental period (n=8), Group (b): Injected with GHS-R antagonist (n=8) once daily throughout the experimental period and Group (c): Vagotomized group (n=8).
Results: Data showed a significant increase in fasting ghrelin level in diabetic group (group II). This was also accompanied by significant increase in food intake and de-crease in body weight. These changes were reversed after treatment with insulin in controlled diabetic group (groupIII). Also, peripherally administered GHS-R antagonist significantly decreased food intake and body weight in all study groups. Treatment with GHS-R antagonist decreased blood glucose level in control group (group I) and controlled diabetic group (group III). Data also showed a significant decrease in basal ghrelin levels in vagotomized rats in all groups. Vagotomy also caused a significant decrease in food intake and body weight in all study groups.
Conclusion: Ghrelin plays a stimulatory role in the hy-perphagia associated with STZ-DM. Also, food intake was significantly decreased by treatment with GHS-R antagonist and vagotomy. In addition, vagotomy contributed to the dissociation of the peripheral signaling of ghrelin, causing significant decrease in food intake and body weight in STZ-DM in rats.