Melatonin (N- acetyl- 5- methoxytryptamine), is an endocrine product of the pineal gland. The present work was conducted to investigate the hepatoprotective effect of exogenous melatonin administration. The findings document the hepatotoxicity of D-galactosamine (GalN). Our results showed a highly significant (P<0.001) decrease in the level of albumin and total protein in rabbits treated with GaIn (50 mg/kg period 20 days) as compared to those levels in the control rabbits (10 ml. normal saline period 20 days). Also there were highly significant (P<0.001) elevations in the levels of alanintransferase (ALT), asparatatetransferase (AST), and alkalinphosphatase (ALP) in the serum of rabbits treated with GalN when these valves were compared to those in control rabbits. We also report that melatonin given at either 09:00h or 21:00h. The current study confirmed the hepatoprotective action of melatonin (in doses 300 μg/kg or 600 μg/kg at 09:00h or 21:00h) against GalN, especially at the dose 600 μg/kg when given at 21:00h treatment with GalN at this time caused a highly significant (P<0.001) increase in the level of albumin and total protein (2.95 ± 0.04 and 6.78 ± 0.10) in experimental group (injected with GaIn in dose 50 mg/kg/day and orally treated with ME in dose 600 μg/kg/day at 21:00h for 20 days) as compared to the control group and a highly significantly (P<0.001) decrease in the levels of ALT, AST, and ALP was (50.33 ± 0.55, 40.50 ± 0.42 and 72.00 ± 1.12), respectively the findings showed that melatonin significantly reduces the toxicity of GalN of melatonin especially when given in the evening.
© 2013 Published by Elsevier Inc.