Dopamine in hypophysial stalk blood of the rhesus monkey and its role in regulating prolactin secretion.
Dopamine in hypophysial stalk blood of the rhesus monkey and its role in regulating prolactin secretion.
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恒河猴垂体柄血中的多巴胺及其调节催乳素分泌的作用。
DOI：
10.1210/endo-108-2-489
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发表时间：
1981
期刊：
影响因子：
4.8
通讯作者：
G. T. Tindall
中科院分区：
文献类型：
--
作者：
Jimmy D. Neill;STEPHEN L. Frawley;P. Plotsky;G. T. Tindall
许多研究表明，多巴胺作为下丘脑催乳素抑制因子在猴子。在本研究中，我们测量了从垂体柄收集的血浆中的多巴胺浓度，并确定这些浓度是否足以解释下丘脑对PRL分泌的抑制作用。首先，我们收集了垂体柄血液从7个卵泡期猴（四个麻醉与戊巴比妥和3与苯环己哌啶）使用经眶手术方法。多巴胺的浓度，用液相色谱-电化学方法测量，平均为0.76纳克/毫升的柄血浆和小于0.1纳克/毫升的外周血浆同时收集。接下来，我们确定了产生与垂体柄血浆中测量的多巴胺浓度相似的外周血浆多巴胺浓度所需的多巴胺输注速率。在7只猴子中，多巴胺输注速率为0.1微克/千克体重。min产生的血浆多巴胺浓度为0.62 ng/ml，而10倍高的速率（1.0 μ g/kg . min）产生的血浆浓度为1.95 ng/ml。然后，我们将这些剂量的多巴胺注入完整的卵泡期动物，茎横断动物和雌激素治疗的茎横断动物，以确定它们对PRL释放的影响。生理剂量的多巴胺（0.1微克/公斤。min）显著抑制了完整卵泡期动物和雌激素处理的茎横断动物的血浆PRL水平，但在未处理的茎横断动物中没有。多巴胺输注速率（1.0 μ g/kg .在后一组中，抑制PRL释放需要min）。这些结果表明，多巴胺是由下丘脑分泌到垂体门静脉血的数量足以占大部分的PRL抑制活性已知是由下丘脑引起的。此外，研究结果表明，雌激素加强多巴胺对灵长类动物催乳素释放的抑制作用，与其在啮齿类动物中的拮抗作用相反。（内分泌学108：489，1981）
Numerous studies are suggestive of dopamine serving as the hypothalamic PRL-inhibiting factor in the monkey. In the present study, we measured dopamine concentrations in plasma collected from the hypophysial stalk and determined whether those concentrations were sufficient to account for the inhibiting effect on PRL secretion exerted by the hypothalamus. First, we collected hypophysial stalk blood from seven follicular phase monkeys (four anesthetized with pentobarbital and three with phencyclidine) using a transorbital surgical approach. Dopamine concentrations, measured with a liquid chromatographic-electrochemical procedure, averaged 0.76 ng/ml in stalk plasma and less than 0.1 ng/ml in peripheral plasma collected contemporaneously. Next, we determined the rate of dopamine infusion required to produce peripheral plasma concentrations of dopamine similar to those measured in hypophysial stalk plasma. In seven monkeys, a dopamine infusion rate of 0.1 microgram/kg BW . min produced plasma dopamine concentrations of 0.62 ng/ml, whereas a 10-fold higher rate (1.0 microgram/kg . min) produced plasma concentrations of 1.95 ng/ml. Then, we infused these doses of dopamine into intact follicular phase animals, stalk-transected animals, and estrogen-treated stalk-transected animals to determine their effect on PRL release. The physiological dose of dopamine (0.1 microgram/kg . min) significantly suppressed plasma PRL levels in intact follicular phase animals and estrogen-treated stalk-transected animals but not in untreated stalk-transected animals. The higher rate of dopamine infusion (1.0 microgram/kg . min) was required to inhibit PRL release in the latter group. These results demonstrate that dopamine is secreted by the hypothalamus into hypophysial portal blood in quantities sufficient to account for much of the PRL-inhibiting activity known to be caused by the hypothalamus. Moreover, the results suggest that estrogen reinforces the inhibitory effect of dopamine on PRL release in primates, in contrast to its antagonistic effect in rodents. (Endocrinology 108: 489, 1981)