Impact of nonlethal levels of Metacid-50 and carbaryl on thyroid function and cholinergic system of Channa punctatus.

With regard to brain acetylcholinesterase and acetylcholine and serum triiodothyronine (T3) and thyroxine (T4) profiles, a biphasic response pattern was elicited in Channa punctatus chronically exposed to nonlethal doses of locally used pesticides, namely, Metacid-50 and Carbaryl. Data revealed that these xenobiotics caused significant inhibition of brain acetylcholinesterase activity and a decrease in thyroxine level accompanied by a concurrent increase in acetylcholine accumulation and T3 level. It is surmised that Metacid-50 and Carbaryl influence both neural and hormonal functions.