INVITRO STUDIES ON THE CHARACTERIZATION OF CELLULAR PROLIFERATION FOLLOWING NEURONAL INJURY IN THE ADULT-RAT BRAIN

While brain injury elicits local cellular proliferation, it is not known whether cells not originating in brain substantially participate in the response. We assessed the time course and phenotype of dividing cells following neuronal damage initiated by microinjection of the neurotoxin ibotenic acid into one caudate nucleus (CN) in adult rat. Proliferation was determined in an in vitro assay measuring incorporation of [3H]thymidine into cellular DNA in cultures of lesioned and uninjected CN. Cellular phenotypes were determined immunocytochemically. Our results show that the proliferative response to brain injury has a rapid onset, peaks within 2 weeks and persists. The majority of proliferating cells that respond to selective neuronal injury are not intrinsic to the central nervous system, but rather are of hematic origin, involving monocytes, macrophages and T-helper lymphocytes. © 1990.