The effects of monosodium l-glutamate administration on the reproduction and serum biochemistry of adult male rabbits

In this study the effects of monosodium l-glutamate (MSG) administration on the reproductive parameters and serum biochemistry of male rabbits were investigated. Sixteen mature male New Zealand mixed-breed of rabbits (Oryctolagus species) weighing 1.1-1.65 kg were used for this study. They were randomised into four groups of four rabbits each. Group A which served as the untreated control, received only distilled water while Groups B, C and D which were the treated groups, received 0.25 g/kg, 0.5 g/kg and 1 g/kg body weight of MSG from a 40% MSG stock solution. The MSG was administered to the rabbits by oral gavage every forty-eight hours for a period of eight weeks. Serum levels of luteinising hormone (LH), testosterone, total cholesterol and total protein, and activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were evaluated on Days 14, 28 and 56 of MSG administration. Results showed that when compared to the untreated group (Group A), on Day 56 of MSG administration the mean serum levels of both LH and testosterone were significantly (P < 0.05) lower in Group D that received 1 g/kg body weight MSG, while the serum cholesterol levels of Group C rabbits that received 0.5 g/kg body weight MSG was significantly (P < 0.05) lower on Day 28 of MSG administration. The mean serum ALT activity of Groups B and C rabbits were significantly (P < 0.05) lower on Day 56 of MSG administration, while the mean serum AST activity of the Group D rabbits was significantly (P < 0.05) higher on Day 14 of MSG administration. There were no significant (P > 0.05) variations in the mean serum total protein between the groups. Testicular histomorphology revealed that MSG administration did not affect the testes of the rabbits as there was no obvious testicular histopathology. It was concluded that administration of MSG to male rabbits significantly lowered serum LH, testosterone and cholesterol levels and serum ALT activity without affecting testicular histomorphology.