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 were examined in astrocyte-enriched cultures from striatum. hippocampus and cerebral cortex derived from newborn mouse brains. Cultures from each 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, cultures were exposed to [H-3] thymidine (0.24 muCI/ml for 16 h). Thymidine-labeling index was determined autoradiographically in flat, polyhedral (type 1) glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes. Morphine significantly inhibited [H-3]thymidine incorporation in astrocytes from all three brain regions, although regional differences in labeling indices were noted. The results show that opiates can intrinsically affect the proliferative rate of astrocytes from diverse brain regions.