Fluctuations in astrocytic basic fibroblast growth factor in the cingulate cortex of cycling, ovariectomized and postpartum animals

In the current studies we investigated the timing of onset and the conditions needed for the maintenance of the upregulation of basic fibroblast growth factor (bFGF) and glial fibrillary acidic protein (GFAP) in the cingulate cortex area 2 (Cg2) that occurs in postpartum animals. We have previously shown that this upregulation is present from day 4 to day 24, and is not seen late in pregnancy (days 21-22). In the current studies, we demonstrate that bFGF and GFAP are both upregulated in Cg2 as early as 3 h postpartum, and are maintained until at least day 24 postpartum in animals deprived of pup stimulation for 8 days prior to perfusion. bFGF and GFAP immunoreactivity returns to prepartum levels by 5-6 weeks post-weaning, and the typical postpartum increase is not further enhanced in multiparous rats. We also show that, although there are significant changes in levels of bFGF immunoreactivity across the phases of the estrous cycle, peak cycling levels remain much lower than those observed in lactating rats. Possible stimuli involved in the induction of bFGF and GFAP in Cg2, and the potential relevance of these changes to the maternal state are discussed.