Abstract

Melatonin, [N- acetyl- 5- methoxytryptamine] (ME), is an endocrine product of pineal gland. The present work was conducted to investigate the hepatoprotective effect of exogenous (ME). Thirty six healthy male rabbits weighting 1500-1700g.were divided into six groups with 6 animals in each group. Animals in the first group served as control, animals in the second, third, fourth, fifth, and sixth groups were intraperitoneally (i.p) injected with D-Galactosamine (GalN) in a single daily dose of 50mg/kg for the period of 20 days for the induction of hepatocellular injury. Animals in the third and fourth groups in addition to GalN were orally treated with ME in a single daily dose of 300µg/kg, as follows: animals in the third group received ME at 9am; and those in the fourth group received ME at 9pm, for the period of 20 days. Animals in the fifth and sixth groups, in addition to GalN, were orally treated with ME in a single daily dose of 600µg/kg, as follows: animals in the fifth group received ME at 9am, and animals in sixth group received ME at 9pm for the period of 20 days. The level of Albumin, Total Protein, Alanintransferase (ALT), Asparatatetransferase (AST), and Alkalin-phosphatase (ALP) in serum was estimated. Results showed that ME significantly (P<0.01) reduced the toxicity of GalN, and that ME is more effective when given at evening times.