Infusion of 3a,5a-THP to the pontine reticular formation attenuates

Whether progesterone (P ) and its metabolite, 5a-pregnan-3a-ol-20-one (3a,5a-THP) have anti-seizure effects through actions in the 4 pontine reticular formation (PRF) was investigated. Concentrations of P and 3a,5a-THP in the PRF were greater in proestrous and 4 hormone-primed rats, that are typically more resistant to seizure-induction, than diestrous and males rats. Ovx, Long-Evans rats with unilateral microinjections into the PRF of 3a,5a-THP (5 mg/0.2 ml), but not P (11 mg/0.2 ml) or vehicle (b-cyclodextrin), had a greater 4 latency and lower incidence of tonic-clonic seizures induced by pentylenetetrazol (PTZ; 70 mg/kg, IP) administration. Infusions that missed the PRF were not effective. These data suggest 3a,5a-THP has anti-seizure effects in part through actions in the PRF.  2000 Elsevier Science B.V. All rights reserved. Theme: Disorders of the nervous system Topic: Epilepsy: anti-convulsant drugs