Department of Veterinary Sciences, University of Turin, Grugliasco, Torino, Italy.
Department of Biochemistry and Cell and Molecular Biology, Faculty of Veterinary Medicine, University of Zaragoza, Zaragoza, Spain.
Reproduction. 2024 Oct 3;168(5). doi: 10.1530/REP-24-0172. Print 2024 Nov 1.
Melatonin plays a crucial role in enhancing reproductive performance in small ruminants. This paper reveals the effects of exogenous melatonin on the placental and endometrial rearrangement in early pregnancy in sheep.
Early pregnancy losses cause 25% of pregnancy failures in small ruminants because of asynchrony between conceptus and uterine signals. In this context, melatonin plays a crucial role in sheep reproductive dynamics, but little is known about its effects during the peri-implantation period. We hypothesized that melatonin supports embryo implantation by modulating the uterine microenvironment. This study aimed to assess the effects of exogenous melatonin on the endometrial and early placental rearrangement. Ten multiparous ewes either did (MEL, n = 5) or did not (CTR, n = 5) receive a subcutaneous melatonin implant (18 mg) 50 days before a synchronized mating. On day 21 of pregnancy, the sheep were euthanized. MEL ewes exhibited a higher prolificity rate (2.8 vs 2.0 embryos/ewe) and plasma progesterone levels (3.84 vs 2.96 ng/mL, P < 0.05) than did CTR ewes. Groups did not differ significantly in embryo crown-rump length. MEL placentas had significantly (P < 0.001) more binucleated trophoblast cells in the chorion region, and ovine placental lactogen expression was significantly (P < 0.05) more strongly upregulated than in CTR. Exogenous melatonin increased significantly (P < 0.05) gene expression of angiogenic factors (VEGFA, VEGFR1, IGF1R), IFNAR2, and PR in the caruncular endometrium. Expression of the MT2 receptor in the endometrium and placenta was significantly (P < 0.05) higher in the MEL group. These results indicate that melatonin implants acted differentially on uterine and placental rearrangement. Melatonin increases differentiation in the placenta and induces changes that could promote vessel maturation in the endometrium, suggesting that it enhances the uterine microenvironment in the early stage of pregnancy in sheep.
褪黑素在提高小反刍动物的繁殖性能方面起着至关重要的作用。本文揭示了外源性褪黑素对绵羊妊娠早期胎盘和子宫内膜重排的影响。
由于胚胎和子宫信号之间的不同步，小反刍动物妊娠早期损失导致 25%的妊娠失败。在这种情况下，褪黑素在绵羊生殖动态中起着至关重要的作用，但在胚胎植入期对其作用知之甚少。我们假设褪黑素通过调节子宫微环境来支持胚胎着床。本研究旨在评估外源性褪黑素对子宫内膜和早期胎盘重排的影响。10 只经产母羊（MEL 组，n = 5；对照组，n = 5）分别在同步配种前 50 天接受皮下褪黑素植入（18 mg）。在妊娠第 21 天，对绵羊进行安乐死。与对照组相比，MEL 组母羊的繁殖力更高（2.8 比 2.0 个胚胎/母羊），血浆孕酮水平更高（3.84 比 2.96ng/mL，P < 0.05）。两组胚胎冠臀长无显著差异。MEL 胎盘在绒毛膜区域有明显更多的双核滋养层细胞（P < 0.001），并且与对照组相比，绵羊胎盘催乳素的表达显著上调（P < 0.05）。外源性褪黑素显著增加了caruncular 子宫内膜中血管生成因子（VEGFA、VEGFR1、IGF1R）、IFNAR2 和 PR 的基因表达（P < 0.05）。MT2 受体在子宫内膜和胎盘中的表达在 MEL 组显著升高（P < 0.05）。这些结果表明，褪黑素植入物对子宫和胎盘重排的作用不同。褪黑素增加胎盘的分化，并诱导可能促进子宫内膜血管成熟的变化，表明它增强了绵羊妊娠早期的子宫微环境。
