Cholera toxin B decreases bicuculline seizures in prenatally morphine- and saline-exposed male rats.

Prenatal morphine exposure on gestation days 11-18 alters bicuculline-induced seizures in rats during development and in adulthood. Adult, morphine-exposed male progeny exhibit an increased latency to bicuculline seizures, which can be reversed by administration of the opioid receptor antagonist naloxone. In chronically morphine-treated adult mice, cholera toxin B (CTX-B) can reverse the effects of chronic morphine administration. Therefore, the present study investigated whether prenatally morphine-exposed rats show a similar response to CTX-B as chronically morphine-treated adult rodents. Prenatally morphine-, saline- and unexposed male progeny were tested for seizure susceptibility with a 7.5-mg/kg intraperitoneal injection of bicuculline in adulthood. CTX-B or saline was injected subcutaneously at 24, 12, and 0.5 h before bicuculline injection. CTX-B decreased the occurrence of bicuculline-induced seizures in both prenatally saline- and morphine-exposed but not unexposed rats. Furthermore, three, but not one, saline injections administered at 12-h intervals prior to bicuculline administration reversed the increase in seizure latency in prenatally morphine-exposed adult males, suggesting an altered responsiveness of the stress system. The present study demonstrates that CTX-B can decrease the occurrence of bicuculline seizures in prenatally stressed rats and that increased seizure latencies in prenatally morphine-exposed male rats may be related to stress responses.