ABSTRACT
The present study was aimed to explore the effects of intraperitoneal injection of growth hormone releasing peptide-6 (GHRP-6), a ghrelin receptor agonist, on food intake and neuronal activity of feeding-related nuclei in the hypothalamus of NMRI mice. Accumulated amount of food intake was measured, and total number of c-fos immunoreactive neurons in arcuate nucleus (ARC), paraventricular nucleus (PVN) and supraoptic nucleus (SON) was counted by immunohistochemistry at 1, 3 and 6 h after the GHRP-6 injection. The results showed that GHRP-6 significantly increased the amount of food intake with a peak at 3 h after the GHRP-6 injection. Meanwhile, GHRP-6 could promote c-fos expression in the ARC and PVN independent of food intake, and the total number of c-fos immunoreactive neurons was peaked at 1 h after injection and then decreased gradually. These results suggest that GHRP-6 may increase food intake in time-dependent manner, which is associated with up-regulations of c-fos protein expression in the ARC and PVN.