RESUMO
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)
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Assuntos
Animais , Ratos , Neurônios , Neurônios/patologia , Óxido Nítrico/efeitos adversos , Hipotálamo Anterior , Hipotálamo Anterior/lesões , Imuno-Histoquímica/métodos , Núcleo Supraóptico , Degeneração Neural/induzido quimicamente , Degeneração Neural/patologia , Núcleo Basal de Meynert/química , Núcleo Basal de MeynertRESUMO
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Assuntos
Humanos , Apoptose , Corticosterona/farmacocinética , Corticotrofos , Proliferação de Células , Glucocorticoides/farmacocinética , HipófiseRESUMO
Pituitary gland and is involved in the stimulationof ACTH secretion. However, to date ithas not been determined whether IL-1Beta is ableto regulate the proliferation of pituitaryACTH-producing cells, like other regulatoryfactors involved in the regulation of ACTHsuch as vasopressin or CRH. The aim of thepresent study was to address whether IL-1Beta isinvolved in regulating the proliferation andapoptosis of pituitary ACTH-secreting cells.Thus, we performed an in vitro study onmonolayer cultures of rat pituitary cells, neutralisingthe possible paracrine effect of IL-1Beta by immunoblockade of the interleukin andlater determining the degree of proliferationor apoptosis of ACTH-secreting cells. Theeffects of immunoblockade were validated bydetermining the modifications in the patternsof the immunohistochemical reaction toACTH-positive cells. Immunoblockade of IL-1Beta decreased the percentage and proliferationof ACTH-positive cells at all time-pointsanalysed, mainly between 6 and 12 h(p<0.01). Moreover, immunoblockade decreasedthe sizes of the cellular and nuclear areas atall time-points studied, with significantdecreases (p<0.01) after 3, 6 and 12 hours.The results obtained suggest that -in the sameway as it regulates the secretion of the hormone-IL-1Beta could be involved in regulating theproliferation of ACTH cells (AU)
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