Abstract
The orexigenic system was discovered in 1998. It consists of two neuropeptides, Orexin A and Orexin B. Researchers have focused more on Orexin A, since its intracerebroventricular injection into the lateral ventricle of the rat's brain causes an increase in the consumption of food. Besides, it seems that, apart from appetite, Orexin A regulates many other physiological functions with unknown regulatory and metabolic mechanisms. Orexin A is produced by a small group of neurons located in and around the lateral hypothalamic area. It has been known for decades that the latter is involved in regulating feeding in mammals. An intravenous injection of Orexin A causes changes in insulin and glucagon plasma concentrations in rats. In this study, we investigated the possible effects of the central administration of porcine Orexin A on glucose-dependent insulinotropic polypeptide plasma concentrations in pigs, and examined whether these changes are related to the possible effect of the neuropeptide on the enteroinsular axis.