MORPHINE SUPPRESSES DNA-SYNTHESIS IN CULTURED MURINE ASTROCYTES FROM CORTEX, HIPPOCAMPUS AND STRIATUM

To determine whether there are regional differences in the ability of opiates to affect astrocyte proliferation, the effects of morphine wer e examined in astrocyte-enriched cultures from striatum. hippocampus a nd cerebral cortex derived from newborn mouse brains. Cultures from ea ch region were continuously incubated in media alone (controls), or in media treated with 1 muM morphine, 1 muM morphine plus 3 muM naloxone , or 3 muM naloxone alone. Before harvesting at 6 days in vitro, cultu res were exposed to [H-3] thymidine (0.24 muCI/ml for 16 h). Thymidine -labeling index was determined autoradiographically in flat, polyhedra l (type 1) glial fibrillary acidic protein (GFAP)-immunoreactive astro cytes. Morphine significantly inhibited [H-3]thymidine incorporation i n astrocytes from all three brain regions, although regional differenc es in labeling indices were noted. The results show that opiates can i ntrinsically affect the proliferative rate of astrocytes from diverse brain regions.