Neuroscience
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Because we believe that macrophage-derived nitric oxide contributes to pathology of demyelinating diseases, we have determined the differential effects of nitric oxide on primary rat glial cells in vitro. Enriched cultures of microglia, astrocytes and oligodendrocytes were treated with S-nitroso,N-acetyl-DL-penicillamine, a nitric oxide-releasing chemical. There was a significantly decreased function of one of the ferrosulfur-containing mitochondrial enzymes after S-nitroso,N-acetyl-DL-penicillamine/nitric oxide treatment in oligodendrocytes and astrocytes compared to microglia, which were much less sensitive to S-nitroso,N-acetyl-DL-penicillamine/nitric oxide at all concentrations. ⋯ These findings suggest that there is differential sensitivity of glial cells to nitric oxide. Although oligodendrocytes and astrocytes are equally susceptible to nitric oxide-induced mitochondrial damage, oligodendrocytes are more sensitive to nitric oxide-induced single stranded DNA breaks, morphological changes and cell death. Compared to both oligodendrocytes and astrocytes, microglia, nitric oxide-producing cells, are resistant to nitric oxide-induced damage.
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The properties of rhythmic low-threshold and multireceptive spinal dorsal horn neurons were determined. Multiple neuron recordings were made via a single electrode in the lumbar spinal cord of pentobarbital-anesthetized or decerebrate, unanesthetized, spinalized rats. The background activity of a total of 223 neurons was analysed: 21.0% of 176 fully characterized neurons were low threshold, 73.3% multireceptive and 5.7% nociceptive-specific neurons. ⋯ Thus, rhythmicity exists in sensory neurons of the spinal dorsal horn probably generated within its local neuronal network and partially modulated by supraspinal descending systems. Rhythmicity is depressed by activity in primary afferent nociceptors. The role of rhythmicity for information transfer and neuronal plasticity is discussed.