Objective: Effects of melatonin on food intake in various species have been important studies with contradictory implications. In this study, we have aimed to investigate the modulatory effects of melatonin on noradrenergic and dopaminergic neurotransmitters in brain areas, LHA, VMN and NAC, which are involved in the regulation of food intake.

Materials and Methods: In this study, 16 wistar albino rats were used. Adult male Wistar rats were divided into two groups and fasted for 24 hours. The first groups of animals were intraperitoneally injected with melatonin (2 mg/kg). Controls received ethanol + saline alone. All animals were decapitated 30 mins after injections and brains rapidly removed. LHA, NAC and VMN were isolated from frozen brain clices by micropunch technique. Catecholamine content of these brain samples was determined by High Performance Liquid Chromotography- Electrochemical Detector (HPLC-ECD).

Results: Administration of melatonin significantly elevated concentrations of noradrenaline and its metabolite, DHPG in LHA and VMN (except DHPG). In the NAC, noradrenaline values were reduced, but DHPG was increased. No significant changes were seen in dopamin and DOPAC levels in NAC.

Conclusion: Melatonin caused an increase noradrenaline and DHPG value in the LHA. This effect of melatonin might be decreased food intake. At the same time melatonin has effects of decrease of noradrenaline value in NAC. These effects show that melatonin could be decreased food intake.