Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA.
Domest Anim Endocrinol. 2010 Feb;38(2):103-14. doi: 10.1016/j.domaniend.2009.08.003. Epub 2009 Sep 16.
Neuropeptide Y (NPY) is a neurohormone that is typically associated with food intake, but it has also been reported to affect the production of progesterone from luteal tissue in vitro. However, NPY has not been previously immunolocalized in the ovine ovary or in the corpus luteum (CL) of any species, and the effects of this neurohormone on luteal function in vivo are not known. Thus, we performed fluorescent immunohistochemistry (IHC) to localize NPY in the ovine ovary and used avidin-biotin immunocytochemistry (ICC) to further define the intracellular localization within follicles and the CL. We then infused NPY directly into the arterial supply of the autotransplanted ovaries of sheep to determine the in vivo effect of exogenous NPY on ovarian blood flow and on the luteal secretion rate of progesterone and oxytocin. Immunohistochemistry revealed that the NPY antigen was localized to cells within the follicles and CL, in the nerve fibers of the ovarian stroma, and in the vessels of the ovarian hilus. In the follicle, the NPY antigen was localized to nerves and vessels within the theca interna layer, and strong staining was observed in the granulosal cells of antral follicles. In the CL, NPY was localized in large luteal cells and in the vascular pericytes and/or endothelial cells of blood vessels, found dispersed throughout the gland and within the luteal capsule. In vivo incremental infusions of NPY at 1, 10, 100, and 1,000 ng/min, each for a 30-min period, into the arterial supply of the transplanted ovary of sheep bearing a CL 11 d of age increased (P< or =0.05) ovarian blood flow. The intra-arterial infusions of NPY also increased (P< or =0.05) in a dose-dependent manner the secretion rate of oxytocin, which was positively correlated (P< or =0.05) with the observed increase in ovarian blood flow. The infusions of NPY had a minimal effect on the secretion rate of progesterone, and similar intra-arterial infusions of NPY into sheep with ovarian transplants bearing a CL over 30 d of age had no significant effect on ovarian blood flow or on the secretion rate of progesterone. These results suggest that NPY acts on the luteal vascular system and the large luteal cells to rapidly stimulate blood flow and the secretion of oxytocin, respectively, which collectively implies a putative role for NPY during the process of luteolysis when increasing amounts of oxytocin are secreted from the ovine CL in response to uterine pulses of prostaglandin F2alpha.
神经肽 Y（NPY）是一种与食物摄入有关的神经激素，但也有报道称其会影响黄体组织中孕酮的产生。然而，NPY 以前并未在绵羊卵巢或任何物种的黄体（CL）中免疫定位，并且该神经激素对体内黄体功能的影响尚不清楚。因此，我们进行了荧光免疫组织化学（IHC）以定位绵羊卵巢中的 NPY，并使用亲和素-生物素免疫细胞化学（ICC）进一步确定卵泡和 CL 内的细胞内定位。然后，我们将 NPY 直接注入绵羊自体移植卵巢的动脉供应中，以确定外源性 NPY 对卵巢血流和黄体分泌孕酮和催产素的速率的体内影响。免疫组织化学显示，NPY 抗原定位于卵泡和 CL 中的细胞、卵巢基质的神经纤维以及卵巢门的血管中。在卵泡中，NPY 抗原定位于内膜层的神经和血管中，并且在窦状卵泡的颗粒细胞中观察到强烈的染色。在 CL 中，NPY 定位于大黄体细胞以及血管周细胞和/或血管内皮细胞中，这些细胞分散在整个腺体和黄体囊中。在体内，将 NPY 以 1、10、100 和 1000ng/min 的增量（每种 30 分钟）连续输注到 11 天龄的 CL 绵羊自体移植卵巢的动脉供应中，增加了（P<或=0.05）卵巢血流。NPY 的动脉内输注还以剂量依赖性方式增加了催产素的分泌率，这与观察到的卵巢血流增加呈正相关（P<或=0.05）。NPY 输注对孕酮的分泌率影响很小，而对超过 30 天龄的 CL 绵羊自体移植卵巢进行类似的动脉内 NPY 输注对卵巢血流或孕酮的分泌率没有显著影响。这些结果表明，NPY 作用于黄体血管系统和大黄体细胞，分别快速刺激血流和催产素的分泌，这共同暗示了 NPY 在黄体溶解过程中的作用，此时绵羊 CL 会因前列腺素 F2alpha 的子宫脉冲而分泌出越来越多的催产素。
