RESUMO
Anterolateral deafferentation of the mediobasal hypothalamus prevented the increase of the plasma corticosterone concentration induced by ether, histamine and electric footshock. Hypothalamus deafferentation also prevented the ether stress-induced increase of the plasma levels of ACTH and beta-endorphin immunoreactivity (ACTHi, beta-ENDi). Infusion of isoproterenol evoked an increase of the plasma levels of corticosterone, ACTHi, beta-ENDi and alpha-MSH immunoreactivity (alpha-MSHi) in sham-operated rats. In rats with a deafferented hypothalamus, the responses of plasma corticosterone and ACTHi to isoproterenol were blocked but the responses of plasma beta-ENDi and alpha-MSHi remained intact. We conclude that circulating beta-ENDi after exposure to ether is of anterior lobe origin while circulating beta-ENDi after infusion of isoproterenol is of intermediate lobe origin.
Assuntos
Hipotálamo Anterior/fisiopatologia , Hipotálamo Médio/fisiopatologia , Hipotálamo/fisiopatologia , Estresse Fisiológico/fisiopatologia , Hormônio Adrenocorticotrópico/sangue , Animais , Corticosterona/sangue , Eletrochoque , Endorfinas/sangue , Éter , Feminino , Histamina , Isoproterenol/farmacologia , Hormônios Estimuladores de Melanócitos/sangue , Ratos , beta-EndorfinaAssuntos
Corticosteroides/fisiologia , Encéfalo/fisiologia , Hormônio Adrenocorticotrópico/metabolismo , Animais , Hormônio Liberador da Corticotropina/metabolismo , Retroalimentação , Sistema Hipotálamo-Hipofisário/fisiologia , Hipotálamo/fisiologia , Técnicas In Vitro , Sistema Hipófise-Suprarrenal/fisiologia , RatosRESUMO
Basal and stimulated CRF release by hypothalamic blocks was studied by coupling the effluent of superfused hypothalamus tissue to a joint pituitary cell-adrenal cell superfusion system and measuring corticosterone production. Log dose-response curves of the adrenal cells for ACTH and of the pituitary cell-adrenal cell system for CRF were linear over the ranges used. Ca++-independent basal CRF release by the hypothalamus could be blocked in vitro by 0.2 mug/ml dexamethasone in the medium, or in vivo by treating the hypothalamus donor rats with corticosterone, 1 mg/rat ip 30 min before decapitation. These treatments did not impair CRF release caused by Veratridine (5 x 10(-6)M or by electrical stimulation. Adrenalectomy increased only basal but not stimulated CRF release. These results indicate that glucocorticoids have a hypothalamic site of action.
Assuntos
Glândulas Suprarrenais/fisiologia , Hipotálamo/fisiologia , Hipófise/fisiologia , Adrenalectomia , Animais , Corticosterona/metabolismo , Corticosterona/farmacologia , Hormônio Liberador da Corticotropina/metabolismo , Cosintropina/farmacologia , Dexametasona/farmacologia , Estimulação Elétrica , Feminino , Técnicas In Vitro , Masculino , Eminência Mediana , Perfusão , Ratos , Extratos de Tecidos , Veratridina/farmacologiaAssuntos
Adrenalectomia , Corticosterona/farmacologia , Hipofisectomia , Hipotálamo/efeitos dos fármacos , Neurotransmissores/metabolismo , Sistema Hipófise-Suprarrenal/fisiologia , Animais , Transporte Biológico , Colina/metabolismo , Dopamina/metabolismo , Hipotálamo/metabolismo , Masculino , Norepinefrina/metabolismo , Ratos , Serotonina/metabolismo , Sinaptossomos/metabolismo , Ácido gama-Aminobutírico/metabolismoAssuntos
Hipotálamo/fisiologia , Hipófise/fisiologia , Hormônios Hipofisários/fisiologia , Hormônio Liberador da Corticotropina/fisiologia , Hormônio Liberador de Gonadotropina/fisiologia , Hormônio Liberador de Hormônio do Crescimento/fisiologia , Humanos , Hormônio Inibidor da Liberação de MSH/fisiologia , Hormônios Estimuladores de Melanócitos/fisiologia , Neurossecreção , Hormônios Liberadores de Hormônios Hipofisários/fisiologia , Fatores Inibidores da Liberação da Prolactina/fisiologia , Somatostatina/fisiologia , Hormônio Liberador de Tireotropina/fisiologiaRESUMO
Rat neurointermediate lobes were superfused in vitro and showed a stable secretion rate of MSH after 30 min. MSH secretion from lobes of untreated rats was reversibly inhibited during superfusion with medium containing 45 mM K+. This inhibition could not be induced using lobes from median eminence lesioned or reserpinized rats. Superfusion with 45 mM K+ also induced release of dopamine from lobes preincubated with the labeled transmitter. It is concluded that the MSH-release inhibiting system present in the rat neurointermediate lobe may be identical to the dopaminergic arcuate-intermediate lobe system.