George S R, Roldan L, Haas D A
Department of Medicine, University of Toronto, Canada.
Neuroendocrinology. 1990 Aug;52(2):191-5. doi: 10.1159/000125572.
The effect of adrenergic influences on Met-enkephalin concentrations in median eminence, neurointermediate pituitary and hypothalamus outside median eminence were examined. Met-enkephalin levels in median eminence were augmented by administration of the alpha 1-adrenergic agonist methoxamine acutely or chronically and decreased by the selective depletion of adrenergic transmitters by 6-hydroxydopamine. Met-enkephalin levels in neurointermediate lobe were decreased by methoxamine but unaffected by depletion of noradrenaline/adrenaline. These results indicate that adrenergic mechanisms maintain Met-enkephalin concentrations tonically in median eminence and deplete Met-enkephalin concentrations in neurointermediate lobe. These results suggest differential adrenergic regulation of hypothalamic proenkephalin neurons terminating in median eminence and neural lobe of pituitary.
研究了肾上腺素能影响对正中隆起、神经垂体中间部以及正中隆起外下丘脑内甲硫氨酸脑啡肽浓度的作用。急性或慢性给予α1-肾上腺素能激动剂甲氧明可使正中隆起中甲硫氨酸脑啡肽水平升高，而用6-羟基多巴胺选择性耗竭肾上腺素能递质则使其降低。甲氧明可使神经垂体中间叶中甲硫氨酸脑啡肽水平降低，但去甲肾上腺素/肾上腺素的耗竭对其无影响。这些结果表明，肾上腺素能机制可维持正中隆起中甲硫氨酸脑啡肽的浓度，而使神经垂体中间叶中甲硫氨酸脑啡肽浓度降低。这些结果提示，肾上腺素能对终止于正中隆起和垂体神经叶的下丘脑前脑啡肽神经元具有不同的调节作用。
