17 beta-Estradiol increases, aging decreases, c-Fos expression in the rat accessory olfactory bulb

In the present paper we investigated the c-Fos immunoreactivity in the acce ssory olfactory bulb (AOB) of juvenile, adult and old rats of both sexes, a s well as the effect of 17 beta -estradiol on the expression of this immedi ate early gene. Basal c-Fos expression in the olfactory bulb decreased with age, and estrogen treatment caused an increase in the number of neurons ex pressing c-Fos in the AOB. The results indicate that both aging and estroge n have roles in the ability of neurons to co-ordinate genetic activity. Our observations may explain the decrease in age-related changes of brain plas ticity, and provide data for the understanding of hormonally regulated neur onal plasticity. NeuroReport 12:3787-3790 (C) 2001 Lippincott Williams & Wi lkins.