Plasticity in the maternal circuit: Effects of experience and partum condition on brain astrocyte number in female rats

Female rats that have received a maternal experience undergo enhanced c-fos expression in a number of brain sites when reexposed to pups. The present 2 studies examined changes in the expression of another brain protein, glia l fibrillary acidic protein (GFAP), which is a major unit of the astrocytic cytoskeleton. In both experiments, primiparous and multiparous female rats were given varying amounts of postpartum contact with pups and overdosed a fter varying intervals, with no pups. Brains were prepared for GFAP immunoh istochemical analysis. In both studies, Day 5 postpartum multiparous subjec ts given additional postpartum contact with pups, when compared with pup-ex posed primiparous subjects, were found to have significantly higher numbers of GFAP positive cells in the medial preoptic area of the hypothalamus, an area critical for the expression of maternal behavior, but not in control sites. In Experiment 2, an opposite effect of parity was found in the media l amygdala and habenula.