LONG-TERM POSTNATAL EFFECT OF PRENATAL IRRADIATION ON THE ASTROCYTE PROLIFERATIVE RESPONSE TO BRAIN INJURY

Pregnant Wistar rats were exposed to a single 1.0 Gy dose of gamma-irr adiation on gestational day 13, 15, 17 or 19. Thirty-day-old male offs pring received a mechanical lesion in the left cerebral hemisphere. On e, 2 or 4 days after the injury the rats were injected with [H-3]thymi dine and sacrificed 4 h after the injection. Thereafter, brain section s were immunostained for GFAP or S100 beta protein, subjected to autor adiography and examined microscopically to record immunopositive astro cytes labelled with [H-3]thymidine. Statistically significant elevatio n of the reactive astrocyte proliferation was revealed on the 2nd day following injury in brains irradiated on gestational day 15. The resul ts represent the first in vivo evidence that a low-dose prenatal gamma -irradiation can induce a long-term increase in the ability of astrogl ia to proliferate in response to injury. (C) 1997 Elsevier Science B.V .