The Effect of Intravascular Injection of Ghrelin on the Mean Plasma Concentrations of Insulin and ACTH in Immature Camels Fed with Diets Containing Different Levels of their Energy Requirements

Introduction: Ghrelin is a peptide hormone secreted from the stomach with both endocrine and paracrine effects. Ghrelin and its mRNA as well as growth hormone (GH) secretagogue receptor mRNAs are expressed in the pancreas and islet cells and regulate insulin release. Also the immounoreactivity of ghrelin is proved to be high in the hypothalamus and parts of the brain responsible for the regulation of the HPA axis. However, the effect of ghrelin on insulin and ACTH secretion before puberty in semi ruminant animals has never been examined. Therefore the purpose of the following research was to determine the effect of ghrelin on insulin and ACTH secretion before puberty in camels. Methods: In this investigation, 12 camels were randomly divided into two groups. Animals in each group were fed with either 50% or 100% energy content in diet for 2 weeks. After 2 weeks camels received 8 mu g ghrelin/Kg body weight into their jugular vein for 4 days. Blood samples were collected from jugular vein 20 minutes after injection of ghrelin. Blood plasma was assayed for plasma insulin and ACTH concentrations by a RIA method. Results: Injection of ghrelin in 50% and 100% dietary energy intake significantly decreased the mean plasma concentrations of insulin and increased ACTH secretion in prepubertal camels. Conclusion: The results of these experiments showed that ghrelin's reducing effect on insulin secretion and its increasing effect on ACTH in prepubertal camels in starvation condition depends on the presence of glucose in their bodies.