FGF-2 immunoreactivity in adult rat ependyma and choroid plexus: Responsesto global forebrain ischemia and intraventricular FGF-2

Fibroblast growth factor 2 (FGF-2) immunoreactivity (IR) was examined in th e ependyma and choroid plexus (CP) of lateral and third ventricles in norma l adult rats, as well as in response to transient forebrain ischemia (TFI) and exogenous FGF-2 delivered intraventricularly for several days by osmoti c pump. Similar patterns of FGF-2 IR were seen in the CP epithelia of both lateral and third ventricles, as well as in ependymal cells of the third ve ntricle and along lateral sides of the lateral ventricles. Consistent stain ing was seen along the apical aspect of epithelial cells facing the cerebro spinal fluid (CSF). Cytoplasmic staining was seen in the absence of ischemi a, and was dramatically reduced in response to TFI. FGF-2 treatment followe d by TFI resulted in sustained FGF-2 IR within CP and ependymal cells, supp orting the idea that these tissues are involved in synthesis and secretion of growth factors into the CSF. In contrast, along the medial sides of the lateral ventricles, adjacent to brain structures such as the hippocampus, c onsistent staining was seen along the basal aspect of the ependymal cells. We propose that at least some regions of ependyma may function to transport molecules such as FGF-2 directly into the underlying brain parenchyma.