Endosulfan and cholinergic (muscarinic) transmission: effect on electroencephalograms and [3H]quinuclidinyl benzilate in pigeon brain.

Single exposure of endosulfan (5 mg/kg) to pigeons (Columbia livia) caused neuronal hyperexcitability as evidenced by spike discharges of 200-500 microV in the electroencephalograms (EEG) from the telencephalon and hyperstriatum, but there was no effect on the ectostriatal area. Cholinergic (muscarinic) receptor binding study using [3H]quinuclidinyl benzilate ([3H]QNB) as a specific ligand indicated that a single exposure to 5 mg/kg of endosulfan caused a significant increase (P less than 0.05) in [3H]QNB binding to the striatal membrane. Behavioral study further indicated that a single dose of 200 micrograms/kg of oxotremorine produced a significant induction in the tremor (P less than 0.01) in endosulfan-pretreated pigeons. The results of this behavioral and biochemical study indicate the involvement of a cholinergic (muscarinic) transmitter system in endosulfan-induced neurotoxicity.