Kotwica J, Bogacki M, Rekawiecki R
Institute of Animal Reproduction and Food Research, Division of Endocrinology and Pathology, The Polish Academy of Sciences, P.O. Box 55, Prawochenskiego 5, 10-718 Olsztyn-Kortowo, Poland.
Domest Anim Endocrinol. 2002 Jul;23(1-2):299-308. doi: 10.1016/s0739-7240(02)00165-0.
The ovarian noradrenergic stimulation or noradrenaline (NA) administration directly to the ovary in cow increases ovarian oxytocin (OT) release and post-translational processing of OT synthesis within a few minutes has been established in both in vivo and in vitro studies. Furthermore, NA affects progesterone secretion and its synthesis by an increase of cytochrome P450scc and 3beta-hydroxysteroid dehydrogenase activity. This effect is mediated via luteal cell beta(1)- and beta(2)-receptors. Their total amount correlates with peripheral progesterone concentrations during the luteal phase and this reflects the ability of the ovary to react to beta-stimulation. On the other hand, ovarian denervation causes a decrease of steroidogenic activity in the CL, an increase of beta-receptors on luteal cells, a delay in follicular development and the disruption of cyclicity. Moreover, decrease of progesterone secretion by 20-30% was seen after brief pharmacological blockade of ovarian beta-receptors in the mid-cycle of cattle. We assume that tonic beta-stimulation of the CL ensures the basal secretion of progesterone, whereas acute noradrenergic activation supports the CL during stressful situations which could impair its function. Conversely, long-lasting increase in blood catecholamine concentrations markedly decreases the number of beta-receptors in CL, presumably due to their down-regulation. Concentrations of dopamine (DA) within the CL are highly correlated with those of NA during the estrous cycle, and are higher in the newly-formed than in the developed corpus luteum, the regressed corpus luteum or the corpus luteum of pregnant females. Bovine CL can synthesise de novo NA from DA as a precursor. Concluding, presented data indicate that noradrenergic stimulation can be an important part of mechanism supporting secretory function of CL.
在奶牛中，卵巢的去甲肾上腺素能刺激或直接向卵巢注射去甲肾上腺素（NA）会增加卵巢催产素（OT）的释放，体内和体外研究均已证实，在几分钟内OT合成的翻译后加工过程也会增加。此外，NA通过增加细胞色素P450scc和3β-羟基类固醇脱氢酶的活性来影响孕酮的分泌及其合成。这种作用是通过黄体细胞的β(1)和β(2)受体介导的。它们的总量与黄体期外周孕酮浓度相关，这反映了卵巢对β刺激的反应能力。另一方面，卵巢去神经支配会导致黄体中类固醇生成活性降低、黄体细胞上β受体增加、卵泡发育延迟以及周期紊乱。此外，在牛的发情周期中期，短暂阻断卵巢β受体后，孕酮分泌减少了20 - 30%。我们假设对黄体的持续性β刺激可确保孕酮的基础分泌，而急性去甲肾上腺素能激活在可能损害其功能的应激情况下支持黄体。相反，血液中儿茶酚胺浓度的长期升高会显著减少黄体中β受体的数量，这可能是由于它们的下调所致。在发情周期中，黄体中的多巴胺（DA）浓度与NA浓度高度相关，且在新形成的黄体中比在发育中的黄体、退化的黄体或怀孕雌性的黄体中更高。牛的黄体可以将DA作为前体从头合成NA。总之，所呈现的数据表明去甲肾上腺素能刺激可能是支持黄体分泌功能机制的重要组成部分。
