Habituação ao estresse em ratos com lesão do nucleo dorsomediano do hipotalamo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

The dorsomedial hypothalamic nucleus (DMHN) participates in the mechanisms whi.ch contral the stress response. The objective of this study was to evaluate the effects of the electrolytic lesion of DMHN on cortisone levels and on habituation to stress. The studied population was 120 rats (Wistar, UNICAMP) with average weight of 2809, divided in three groups: control, simulated and lesioned. The simulated group underwent brain surgery; the lesioned group was submited to the same procedure, but received the eletrolytic lesion guided by stereotaxy. After 15 days of adaptation, the three groups were equally submited to uninterrupted sessions. of stress trough immobilization, for three, nine and fifteen consecutive days. After each session a sample of ea.ch group. was sacrificed by decapitation, and blood samples were taken to determine cortisone levels. The brains of the lesioned rats underwent histological analysis in order to prove bilateral lesion of DMHN and confirm their inclusion. Results: the cortisone blood levels in lesioned rats increased significantly in basal conditions, decreasing afterwards to levels which remained unchanged trough the periods of immobilization stress. Our results suggest that DMHN lesion alters the hypothalamic-pituitary-adrenal axis, modifying the animal s basal response. The lesioned rats did not recognize the stressor stimuli; therefore the habituation process was not triggered. Key words: stress, habituation, hypothalamus, lesion, dorsomedial nucleus

ASSUNTO(S)

hipotalamo stress (fisiologia) - testes habituação (neuropsicologia)

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