Action of glucocorticoids on survival of nerve cells: Promoting neurodegeneration or neuroprotection?

摘要: Extensive studies during the past decades provided compelling evidence that glucocorticoids (GCs) have potential to affect development, survival and death of neurones. These observations, however, reflect paradoxical features GCs, as they may be critically involved in both neurodegenerative neuroprotective processes. Hence, we first address different aspects complex role GCs neurodegeneration neuroprotection, such concentration dependent actions on neuronal viability, anatomical diversity GC-mediated mechanisms brain species strain differences GC-induced neurodegeneration. Second, modulatory action development ageing central nervous system, well contribution altered GC balance pathogenesis disorders is considered. In addition, survey recent data possible underlying GCs. As such, two major will discerned: (i) GC-dependent offensive events, inhibition glucose uptake, increased extracellular glutamate concomitant elevation intracellular Ca 2+ , decrease GABAergic signalling regulation local concentrations by 11b-hydroxysteroid dehydrogenases; (ii) GC-related cellular defence mechanisms, after-hyperpolarization, synthesis release neurotrophic factors lipocortin-1, feedback currents induction antioxidant enzymes. The particular relevance these effects discussed.