MALAOXON-INDUCED BRAIN PHOSPHOINOSITIDE TURNOVER AND CHANGES IN BRAINCALCIUM LEVELS BY FEMALE GENDER IN PREGNANT AND NONPREGNANT CONVULSING AND NON-CONVULSING RATS

Alterations in malaoxon-(MO)-induced brain regional phosphoinositide ( PI) turnover and in brain calcium levels were studied in female non-pr egnant and pregnant rats, and in their offspring. The adult rats were followed for 1 or 4 h after MO for tonic-clonic convulsions. A dose of 8.2 mg kg-1 of MO caused similar convulsions In 74% of the pregnant r ats as we have reported in young male rats with a dose of 39.2 mg kg-1 .1 However, convulsions did not occur in non-pregnant female rats. Ino sitol and inositol monophosphate levels were similar in all control ra ts. MO decreased brain inositol both in pregnant and non-pregnant fema le rats, and in the cerebellum of the offspring. In contrast to the fi ndings in male rats, MO only randomly increased brain inositol-1-phosp hate in female rats, or in their offspring. However, cerebral inositol -4-phosphate levels were similarly increased both in the non-pregnant and the pregnant rats irrespectively of convulsions. MO did not elevat e cerebral Ca2+ in female rats or their offspring, in contrast to the male rats.1 The present results suggest that female rats are more sens itive than male rats to MO-induced PI signalling, and during pregnancy , also to MO-induced overt convulsions, but not to changes in cerebral Ca2+.