Effects of pinealectomy and exogenous melatonin on serum leptin levels in male rat

The effects of pinealectomy and exogenous melatonin (N-acetyl-5-methoxytryp tamine) on serum leptin levels were investigated in rats. Exogenous adminis tration of melatonin to intact rats resulted in significant decreases in se rum leptin levels (P < 0.05) compared to those of the intact control group. Serum leptin levels were significantly elevated in the pinealectomised rat s in comparison to the sham-pinealectomised animals (P < 0.001) and were si gnificantly suppressed by exogenous administration of melatonin compared to those of non-treated pinealectomised rats ( P < 0.001). Hormone concentrat ions in the melatonin-treated pinealectomised group were found to be simila r to those seen in the sham-pinealectomised group. These results suggest th at pineal gland has an effect on leptin release. (C) 2001 Elsevier Science B.V. All rights reserved.