Neonatal endosulfan neurotoxicity: behavioral and biochemical changes in rat pups.

Repeated administration of 0.5 mg/kg endosulfan (for 5 days a week) for 3 and 5 weeks of age, produced no significant alteration either in the binding of 3H-5HT to frontal cortical membranes or in foot-shock induced fighting behavior. However, administration of 1 mg/kg endosulfan for 5 weeks caused a significant increase in 3H-5HT binding as well as in foot shock induced aggressive behavior. The endosulfan-induced increase in aggressive behavior and increased binding of 3H-5HT were detectable even 8 days after the cessation of endosulfan treatment. Scatchard analysis revealed that exposure to endosulfan altered the affinity (KD) of the receptors without causing any significant change in maximum number of high affinity binding sites (Bmax). The endosulfan-induced fighting behavior was blocked by the pretreatment of animals with methysergide, a 5-HT blocker. These results suggest an involvement of serotonergic systems in the neonatal neurotoxicity of endosulfan.