Differential effects of reproductive and hormonal state on basic fibroblast growth factor and glial fibrillary acid protein immunoreactivity in the hypothalamus and cingulate cortex of female rats.

Morphological changes in astrocytes occur in a number of brain regions including the hypothalamus and hippocampal regions as a function of hormonal and reproductive state. Because basic fibroblast growth factor has been shown to play an important role in morphological changes in astrocytes, we investigated whether basic fibroblast growth factor immunoreactivity would also be influenced by reproductive state and circulating gonadal steroids. To do this we compared astrocytic basic fibroblast growth factor and glial fibrillary acid protein immunoreactivity in hypothalamic nuclei and the cingulate cortex, area 2 among groups of cycling, late pregnant and lactating rats as well as in ovariectomized and ovariectomized hormone-replaced females. Significant differences in both basic fibroblast growth factor and glial fibrillary acid protein immunoreactivity were observed across groups in the supraoptic nucleus, parvocellular paraventricular nucleus, medial preoptic area of the hypothalamus and cingulate cortex 2. The pattern of change in basic fibroblast growth factor and glial fibrillary acid protein immunoreactivity varied across regions both in direction and magnitude. For example, although in the supraoptic nucleus ovariectomized rats had lower levels of basic fibroblast growth factor-ir than cycling females, this pattern was reversed within cingulate cortex. Overall the results of this study suggest that reproductive and hormonal states are associated with robust changes in basic fibroblast growth factor and glial fibrillary acid protein immunoreactivity in a number of brain areas but that the changes observed vary in magnitude as well as direction from one brain region to another.