Effect of Central Adrenomedullin on Behavioral Changes in the Japanese Quail

Background and Objective: Adrenomedullin (AM), primarily extracted from the adrenal medulla of humans, contains 52 amino acids. It is reported to have a powerful hypotensive and anorexic effect on mammals. This study aimed to clarify the role of AM in avian species as an alternative vertebrate model. Materials and Methods: Adult male Japanese quail (Coturnix japonica) were assigned into 4 groups; besides the control (vehicle) group, AM was administrated intracerebroventricular (ICV) with doses of 0.1, 0.5 and 1.0 nmol/10 μL saline to determine its influence on food and water intake, body temperature and gross locomotor activity. Moreover, immunohistochemical staining was conducted to determine the effect of AM on changes in hypothalamic chemistry. Also, another trial was conducted to detect the effect of astressin as a corticotropin-releasing hormone antagonist on AM. Results: The quails centrally injected with AM had reduced body weight and food intake dose-dependently at 2, 4 and 8 hrs after injection, but not water intake, increases in locomotor activities and transient non-significant elevation in body temperature. Japanese quails that received central AM showed an increase in c-Fos immunoreactivity in the dorsomedial hypothalamus (DM), ventromedial hypothalamus (VMH) and paraventricular Magnocellular (PaMC). The paraventricular parvocellular (PaPc) and arcuate nucleus (ARC) were significantly influenced, while the lateral hypothalamus (LH) was not significantly affected. Receptors’ antagonistic effect of corticotrophin-releasing factor (CRF) showed no changes in AM-associated anorexia. Conclusion: Exogenous human AM-ICV administration has a CRF receptor non-dependent anorexigenic effect on locomotor activity and transient body temperature. Japanese quail exhibits a change in hypothalamic chemistry along with activation of VMH, DM and PaPC.