Castration alters susceptibility of male rats to specific seizures.

Studies in female rats indicate that estrogen reduction has both pro- and anticonvulsant effects on seizures, but that the respective effects are limited to specific types of seizures at selected doses of picrotoxin. This study was conducted to see if testosterone reduction had parallel effects on seizure susceptibility in males. Male rats were given castration or sham operations and allowed 3 weeks to recover. The latencies to myoclonic, focal, akinetic, and generalized tonic-clonic (GTC) seizures were scored in independent groups of sham-operated or castrated males after injection with picrotoxin (3.5-7.5 mg/kg). The results showed that castrated males had significantly shorter latencies to GTC seizures than sham-operated males at the 3.5 mg/kg and 5.5 mg/kg doses of picrotoxin. There were no significant differences in the latencies to myoclonic, focal, or akinetic seizures between the two surgical groups. The findings suggest that, unlike endogenous estrogen, endogenous testosterone exerts only an anticonvulsant effect and that the effect is limited to GTC seizures.