| Research Abstract |
To clarify the cellular mechanisms through which hypothalamic magnocellular neurons send their fibers to the terminal region, namely the pituitary including the median eminence, we have performed several types of experiments. First, we have found that the median eminence was composed with the POMC-containing neuronal cell bodies, in addition to neuronal fibers, blood vessel-devived cells and pia mater-derived cells(Neuroendocrinology, 1992). During the developmental and/or regeneration process, only pia mater cells changed coordinately with the fiber elongation, suggesting the importance of the pia mater in the regeneration process. Further, the pia mater tissues implanted onto the surface of the median eminence were heavily invaded with regene-rating fibers after hypophysectomy(BRAIN RES,in press). These finding may indicate the existing of an important factor(s) releasable from the pia mater cells during developmental and/or regeneration process. In the next step, we prepared meninge
… More
al(the pia mater and arachnoid)cell cultures and then collected the medium conditioned by the cultured cells. The medium was found to contain a certain neurotrophic factor(s) using an in vitro system. The factor(s) was differed from FGF in the action spectrum on the neuronal cell survival(Neuroendocrinology, 1992). Finally, we have found that the neurotrophic activity is due to multiple factors contained in the medium, but mainly through IGF-II and IGFBP-2(Sinkeikagaku, in Japanese, 1994).In addition to IGF-II/IGFBP-2, the medium contained extremely low levels of an unidentified factor which was essential for IGF-II actions on neuronal cells. Further more, the medium was found to contain a lot of protein molecules which were very important in the regulation of neuronal survival or maintenance. For example, beta-trace protein was shown to be secreted from the pia mater cells. The preset studies raise the possibility, therefore, that the pia mater(and/or arachnoid)plays important roles in the regulation not only the blood/CSF barrier but also the parenchymal cell functions in the brain. Less
|
