PRENATAL MORPHINE EXPOSURE INDUCES AGE-RELATED-CHANGES IN SEIZURE SUSCEPTIBILITY IN MALE RATS

The purpose of this study was to investigate the effects of prenatal e xposure to morphine (5-10 mg/kg on days 11-18 of gestation) on fluroth yl seizure susceptibility in adult and developing male rats. In adult rats, prenatal morphine exposure increased the threshold to clonic sei zures but not to tonic-clonic seizures. The effects of prenatal morphi ne exposure on clonic seizures were age dependent. At postnatal day (P ND) 15, prenatal drug exposure did not alter the seizure threshold. At PND 25, there was a reduction in the threshold but by PND 38, the clo nic seizure threshold was increased and this increase persisted into a dulthood. Prenatal exposure to morphine did not after the tonic-clonic seizure threshold in any age group of intact male rats. A group of ma le rats prenatally exposed to morphine was gonadectomized in adulthood . In gonadectomized rats both clonic and tonic-clonic thresholds were increased. These results suggest that exposure to morphine during mid to late gestation induces age-dependent alterations in the susceptibil ity to clonic but not tonic-clonic seizures. In adult male rats the th reshold to tonic-clonic seizures is influenced by prior gonadectomy in adulthood. (C) 1998 Elsevier Science Inc.