Variations of neuronal nitric oxide synthase after hypophysectomy suggest a neuroprotective effect of nitric oxide in response to damage of the neurons of the hypothalamic supraoptic nucleus in the rat

ABSTRACT

The hypothalamic-neurohypophyseal systemoffers an ideal model to study the processes ofnerve degeneration/regeneration after lesionscaused by cutting the hypophyseal stalk, orhypophysectomy. Additionally, the magnocellularneurons comprising it contain nitricoxide, and its enzyme, neural nitric oxide synthase,shows important variations in functionalalterations of the hypothalamic-neurohypophysealsystem. Currently, there is still some controversyas regards whether nitric oxide exertsneurodegenerative or neuroprotective effects inthe nervous system. Here we performed a quantitativeand qualitative study of the variationsin the neuronal activity of nitric oxide synthase,using immunohistochemistry, and of itsmRNA, by in situ hybridization, in the magnocellularneurons of the supraoptic nucleus of thehypothalamus of hypophysectomised rats withsurvival periods of 10-30 days. Our morphologicaland morphometric results and thosepertaining to neuronal quantification and opticaldensity point to a neuroprotective effect ofnitric oxide on magnocellular neurons duringthe regenerative process of the supraopticnucleus that occurs after hypophysectomy (AU)

RESUMEN

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