Ndiaye Kalidou, Poole Daniel H, Pate Joy L
Department of Animal Sciences, The Ohio State University/Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA.
Biol Reprod. 2008 Apr;78(4):786-93. doi: 10.1095/biolreprod.107.065938. Epub 2007 Dec 19.
The corpus luteum (CL) produces oxytocin (OXT), which has been proposed to regulate the pulsatile release of prostaglandin F2alpha during luteolysis in ruminants. This action of OXT is mediated via oxytocin receptors (OXTRs) present on uterine epithelial cells. It is hypothesized that luteal OXT acts as a paracrine regulator of resident immune cells. In the present study, OXTR mRNA expression in bovine lymphocytes was analyzed, as well as its regulation during the estrous cycle. OXTR transcripts were observed in freshly purified bovine peripheral blood mononuclear cells and T lymphocytes. OXTR mRNA in bovine lymphocytes on Day 3 was numerically greater than but not significantly different from that of Day 19 of the estrous cycle (P=0.091). In cultured T cells, estradiol (E2) treatment significantly increased the steady-state concentrations of OXTR mRNA, but the stimulatory effect of E2 was inhibited by the addition of progesterone (P4). Each of the major T cell subsets (CD4+, CD8+, and gamma delta+) expressed OXTR mRNA, with no significant difference in expression among them. Western blot analyses demonstrated the presence of the bovine OXTR protein at about 45 kDa in lymphocytes, as well as expression of the 14-kDa precursor of OXT. When lymphocytes were treated with OXT, intracellular concentrations of calcium ([Ca2+]i) were rapidly and dramatically increased. This study demonstrated that bovine lymphocytes express OXTRs and that this expression can be regulated in a steroid-dependent manner. Furthermore, OXT elicited a functional [Ca2+]i response in T lymphocytes, supporting the possibility that OXT within the CL could act as a paracrine or autocrine regulator of resident T lymphocytes.
黄体（CL）产生催产素（OXT），有人提出它可调节反刍动物黄体溶解过程中前列腺素F2α的脉冲式释放。OXT的这一作用是通过子宫上皮细胞上存在的催产素受体（OXTRs）介导的。据推测，黄体OXT作为驻留免疫细胞的旁分泌调节因子发挥作用。在本研究中，分析了牛淋巴细胞中OXTR mRNA的表达及其在发情周期中的调节情况。在新鲜纯化的牛外周血单核细胞和T淋巴细胞中观察到了OXTR转录本。发情周期第3天牛淋巴细胞中的OXTR mRNA在数值上高于第19天，但差异不显著（P = 0.091）。在培养的T细胞中，雌二醇（E2）处理显著增加了OXTR mRNA的稳态浓度，但添加孕酮（P4）可抑制E2的刺激作用。每个主要的T细胞亚群（CD4 +、CD8 +和γδ +）均表达OXTR mRNA，它们之间的表达无显著差异。蛋白质印迹分析表明，淋巴细胞中存在约45 kDa的牛OXTR蛋白，以及14 kDa的OXT前体的表达。用OXT处理淋巴细胞时，细胞内钙浓度（[Ca2 +]i）迅速且显著增加。本研究表明，牛淋巴细胞表达OXTRs，且这种表达可受类固醇依赖性方式调节。此外，OXT在T淋巴细胞中引发了功能性的[Ca2 +]i反应，支持了黄体中的OXT可能作为驻留T淋巴细胞的旁分泌或自分泌调节因子的可能性。
