Chemoprotection of lipoic acid against microcystin-induced toxicosis in common carp (Cyprinus carpio, Cyprinidae)

Abstract

This paper evaluated the chemoprotective effect of lipoic acid (LA) against microcystin (MC) toxicity in carp Cyprinus carpio. To determine the LA dose and the time necessary for the induction of three different classes (alpha, mu and pi) of glutathione S-transferase (GST) gene transcription, carp were i.p. injected with 40 mg/kg lipoic acid solution. A group was killed 24 h after the first i.p. injection (condition 1); another group received two i.p. injections with a 24 h of interval between each one and was killed 48 h after the first injection (condition 2) and a third group received one i.p. injection and was killed 48 h latter (condition 3).Results showed that LA was effective in promoting an increase in GSTs gene transcription in liver only in the condition 2. A second experiment was done, where carp pre-treated with LA (condition 2) were gavaged twice with a 24 h interval with 50 μg MC/kg. Ninety-six hours after experiment beginning, carp were killed, and organs were dissected. Results of GST activity in liver and brain suggest that LA can be a useful chemoprotection agent against MC induced toxicity, stimulating detoxification through the increment of GST activity (brain) or through reversion of GST inhibition (liver).