INDUCTION OF FOS PROTEIN IN THE PIRIFORM CORTEX AFTER BRAIN INJURY IN PENTOBARBITAL-ANESTHETIZED RATS - LACK OF EFFECT OF LACTATION

The ability of lactation and progesterone administration to inhibit the induction of Fos protein in the piriform cortex after brain injury in pentobarbital-anaesthetized rats was assessed in three studies. Consistent with previous reports we found that brain injury-induced Fos expression in the piriform cortex could be eliminated by the administration of the non-competitive NMDA receptor antagonist MK 801 (4 mg/kg i.p.). Fos induction was not reduced, however, in lactating darns (days 7-9) post-partum or in progesterone-treated males. These results are not consistent with the hypothesis that suckling stimulation and progesterone have a direct effect at the NMDA receptor complex.