Ponce-Barajas Patricio, Colazo Marcos G, Behrouzi Amir, Ree Todd O, Kastelic John P, Ambrose Divakar J
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 1C9, Canada.
Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada.
Animals (Basel). 2023 Jul 12;13(14):2283. doi: 10.3390/ani13142283.
There is evidence that replacing the gonadotropin-releasing hormone (GnRH) with porcine luteinizing hormone (pLH) to synchronize ovulation prior to artificial insemination (AI) increased pregnancy per AI in dairy cows without affecting blood progesterone (P) concentrations. Whether morphologic, steroidogenic, and transcriptomic differences exist among corpora lutea (CL) formed after ovulation induced by GnRH and pLH is unclear. Our main objective, therefore, was to compare CL characteristics between GnRH- and pLH-induced CL. In 24 non-lactating Holstein cows, ovulations were spontaneous (Spont-Ov) or induced with 100 µg GnRH, 25 mg pLH, or 1 mg estradiol benzoate (EB), with CL excised 12 d after ovulation. In pLH- versus GnRH-treated cows, the duration of elevated LH (above baseline) was prolonged (10 versus 6 h, respectively, < 0.01), but CL dimensions, pixel intensity of CL images, proportions of steroidogenic and non-steroidogenic luteal cells, and mean plasma LH did not significantly differ. Post-ovulation mean plasma P (ng/mL) did not differ among Spont-Ov (3.0) pLH (3.1) or GnRH (3.0) cows but were lower in EB cows (2.0). In vitro P concentration was greater in luteal explants of pLH-treated cows than in all other groups (combined means, 16.0 vs. 12.3 µg/mL, < 0.02). Relative abundance of mRNA for oxytocin receptor () was 2-fold higher ( < 0.01) in CL of pLH vs. GnRH cows and highest in Spont-Ov CL. In summary, pLH-treated cows had a longer LH peak, and greatest luteal tissue concentrations and in vitro production of P. We inferred that increased P concentrations at the ovarian-uterine level in pLH-treated cows could have promoted embryo development and increased pregnancy per AI.
有证据表明，在人工授精（AI）前用猪促黄体生成素（pLH）替代促性腺激素释放激素（GnRH）来同步排卵，可提高奶牛每次人工授精后的妊娠率，且不影响血液孕酮（P）浓度。GnRH和pLH诱导排卵后形成的黄体（CL）在形态学、类固醇生成和转录组学上是否存在差异尚不清楚。因此，我们的主要目的是比较GnRH和pLH诱导的CL之间的CL特征。在24头非泌乳荷斯坦奶牛中，排卵为自发排卵（Spont-Ov）或用100μg GnRH、25mg pLH或1mg苯甲酸雌二醇（EB）诱导排卵，排卵后12天切除CL。与GnRH处理的奶牛相比，pLH处理的奶牛促黄体生成素（高于基线）升高的持续时间延长（分别为10小时和6小时，P<0.01），但CL尺寸、CL图像的像素强度、类固醇生成和非类固醇生成黄体细胞的比例以及平均血浆促黄体生成素没有显著差异。排卵后，Spont-Ov奶牛（3.0）、pLH奶牛（3.1）或GnRH奶牛（3.0）的平均血浆P（ng/mL）没有差异，但EB奶牛（2.0）的平均血浆P较低。pLH处理奶牛的黄体组织外植体中的体外P浓度高于所有其他组（合并平均值，16.0对12.3μg/mL，P<0.02）。与GnRH奶牛相比，pLH奶牛CL中催产素受体（）mRNA的相对丰度高2倍（P<0.01），且在Spont-Ov CL中最高。总之，pLH处理的奶牛有更长的促黄体生成素峰值，黄体组织浓度和P的体外产量最高。我们推断，pLH处理的奶牛在卵巢-子宫水平上P浓度的增加可能促进了胚胎发育并提高了每次人工授精后的妊娠率。
