Immunocytochemical localization of basic fibroblast growth factor in the rat pineal gland

The immunocytochemical localization of basic fibroblast growth factor (b-FGF) during the postnatal development of the rat pineal gland was studied using a polyclonal antibody against the fraction 1-24 of bovine recombinant b-FGF. Basic FGF immunoreactivity was evident from day 20 after birth in the endothelial cells and perivascular spaces of the gland. Although b-FGF immunostaining showed its maximal expression at 30-45 days, it was maintained throughout the entire study period (up to 6 months), mainly in the distal zone of the gland. Pinealocytes did not show b-FGF immunoreactivity at any time. There were no differences in the localization patterns or the intensity of b-FGF immunostaining after the prenatal denervation with DSP-4, a neurotoxic amine. The physiological role of b-FGF in the adult pineal gland remains unknown; however, it does not seem to play a major role during the cytodifferentiation period of the parenchymal cells, or during the neovascularization in the early postnatal days. Furthermore, its immunocytochemical expression is not affected by the prenatal sympathetic denervation with DSP-4, in contrast with other neurotropic factors.