DEVELOPMENTAL-CHANGES IN DISTRIBUTION PATTERNS OF PHENCYCLIDINE-INDUCED C-FOS IN RAT FOREBRAIN

In the forebrain of 56-day-old rats, histochemical studies revealed th at the subcutaneous injection of a psychotomimetic phencyclidine (PCP; 1 and 10 mg/kg) induced a dose-related and dense nuclear c-fos-like i mmunoreactivity in the pyriform cortex, layers IV-VI of the neocortex and septum, but a sparse c-Fos immunostaining in the olfactory tubercl e and mid-lateral striatum. Infant rats at postnatal day 8 expressed m uch fewer and more confined c-fos-positive cells in the neocortex than young adult rats following PCP injection. However, a similar expressi on pattern of PCP-induced c-Fos was observed in the pyriform cortex, m id-lateral striatum, olfactory tubercle and septum between the infant and adult periods. These developmental changes in the regional distrib ution of a neuronal activity marker, c-Fos, suggest that neuronal popu lations involved in PCP-induced abnormal behavior are influenced by po stnatal development, at least, in the neocortex. (C) 1997 Elsevier Sci ence Ireland Ltd.