Reparation of chlorpyrifos-induced impairment by thyroxine and vitamin C in fish.

The organophosphate pesticide chlorpyrifos significantly decreased the specific activities of catalase (CAT) and lactate dehydrogenase (LDH) in brain, liver, gill and skeletal muscle of the freshwater catfish, Heteropneustes fossilis. It may be due to binding of the pesticide or its metabolite(s) with the enzyme molecules or affecting the synthesis and/or degradation of the enzymes. RNA and protein content also declined significantly in different tissues of the fish in response to chlorpyrifos, which may be due to alterations in turnover of macromolecules involved in protein synthesis. Administration of thyroxine (T4) and ascorbic acid (vitamin C) separately or conjointly to chlorpyrifos-exposed fish brought CAT, LDH, RNA and protein up to their control levels. The protective effect may be attributed to hormone, vitamin and pesticide interaction. Therefore, chlorpyrifos-induced impairment in antioxidative, anaerobic and protein synthesizing capacity can be repaired by ascorbic acid and T4 in fish.