Dopamine receptors of the monkey anterior pituitary in various endocrine states.
Dopamine receptors of the monkey anterior pituitary in various endocrine states.
复制标题
不同内分泌状态下猴垂体前叶的多巴胺受体。
作者：
M. Cronin;D. Koritnik
成年食蟹猴处死后，取其垂体前叶，用多巴胺（DA）拮抗剂[~ 3 H]螺哌隆标记DA受体。[3 H]胡椒酮结合的饱和等温线表明解离常数为0.09 nM，最大位点为170 fmol/mg测定蛋白（n = 2）。竞争性研究验证了[3 H]螺哌隆标记DA受体的假设; 12种化合物的效力顺序适合于多巴胺能相互作用，与其他哺乳动物垂体前叶中发现的顺序相似。将标记90%特异性结合位点的[3 H]螺哌隆浓度（0.76 nM）用于估计个体猴垂体前叶中的总DA受体活性。妊娠猴中的[3 H]螺哌隆结合率大于卵巢切除和哺乳期雌性或完整雄性猴中的结合率（P <0.05或0.01）。产后哺乳组的[3 H]螺哌隆结合活性高于骑自行车组（P <0.05）。测定PRL、雌二醇、睾酮、孕酮和脱氢表雄酮的血清浓度证实了处死时个体猴的预测激素状态。由于DA是一种PRL抑制激素，因此血清PRL浓度与[3 H]螺哌隆结合程度呈正相关（r2 = 0.74）。这一观察结果，结合已知的肥大和/或增生的mammotroph在怀孕期间，支持的假设，DA受体与垂体前叶的PRL细胞。
The anterior pituitary of adult Macaca fascicularis monkeys was removed when they were killed and the potent dopamine (DA) antagonist [3H]spiperone was used to label DA receptors. Saturation isotherms of [3H]piperone binding indicated a dissociation constant of 0.09 nM and maximal sites of 170 fmol/mg assay protein (n = 2). Competition studies validated the hypothesis that [3H]spiperone labeled DA receptors; the order of potency of 12 compounds was appropriate for a dopaminergic interaction and was similar to the order found in the anterior pituitary of other mammals. A concentration of [3H]spiperone that would label 90% of the specific binding sites (0.76 nM) was used to estimate the total DA receptor activity in the anterior pituitary of individual monkeys. [3H]spiperone binding in pregnant monkeys was greater than the binding in ovariectomized and lactating females or intact males (P less than 0.05 or 0.01). The postpartum lactating group contained more [3H]spiperone binding activity than the cycling group (P less than 0.05). Determination of the serum concentrations of PRL, estradiol, testosterone, progesterone, and dehydroepiandrosterone confirmed the predicted hormonal status of the individual monkeys at the time of sacrifice. Because DA is a PRL inhibitory hormone, it was of interest that the serum PRL concentration was positively correlated with the degree of [3H]spiperone binding (r2 = 0.74). This observation, combined with the known hypertrophy and/or hyperplasia of the mammotroph during pregnancy, supports the hypothesis that the DA receptor is associated with the PRL cell of the anterior pituitary.