AN INHIBITORY EFFECT OF INTERFERON-GAMMA ON THE INJURY-INDUCED ASTROCYTE PROLIFERATION IN THE POSTMITOTIC RAT-BRAIN

Influence of interferon gamma (IFN gamma) on astrocytes proliferating in response to unilateral injury of the cerebral hemisphere was invest igated in 30-day-old rats. The brain injury was followed by an immedia te injection of IFN gamma into the lesion cavity. On 1st or 2nd day fo llowing injury the animals were injected with [H-3]thymidine and kille d 4 h after the injection. The proliferating astrocytes were visualise d by combination of immunocytochemical staining for glial fibrillary a cidic protein (GFAP) and autoradiography. Thereafter, numbers of GFAP- immunopositive and autoradiographically-labeled astrocytes located wit hin the region of injury were counted. On the day 1 after injury no ef fect of lFN gamma administration was seen. However, on day 2 the avera ge 43% reduction of the number of proliferating astrocytes was recorde d. The reduction showed no dose-dependent changes. This in vivo eviden ce of IFN gamma-induced suppression of astrocyte proliferation was con sidered in relation to other determinants of astrocyte reactivity exis ting in the injured brain. (C) 1997 Elsevier Science B.V.