INTRACEREBRAL INJECTION OF INTERFERON-GAMMA INHIBITS THE ASTROCYTE PROLIFERATION FOLLOWING THE BRAIN INJURY IN THE 6-DAY-OLD RAT

The present study examines the influence of interferon-gamma (IFN-gamm a) on the astrocyte proliferation in the rat brain injured within the early period of postnatal development. Six-day-old male rats received a lesion in the left cerebral hemisphere and a single injection of rec ombinant rat IFN-gamma into the lesion cavity. One or 2 days after the injury the rats were injected with H-3-thymidine. Brain sections were immunostained for glial fibrillary acidic protein (GFAP), subjected t o autoradiography, and examined microscopically to record proliferatin g GFAP-immunopositive astrocytes labeled with H-3-thymidine. In the IF N-gamma-injected rats, a statistically significant decrease in the int ensity of reactive astrocyte proliferation was revealed. On day 1 afte r injury the intensity of astrocyte proliferation showed dose-dependen t changes. Relations between the astrocyte reactivity and multiple fac tors existing in the injured and IFN-gamma-injected brain are discusse d. The results represent the first in vivo evidence of a dose-dependen t action of IFN-gamma on the astrocyte proliferation in response to in jury. (C) 1997 Wiley-Liss, Inc.