Comparison of the endocrinological and immunological results of different induction of parturition methods in ewes

Reproductive Hormones Mediate Intestinal Microbiota Shifts during Estrus Synchronization in Grazing Simmental Cows

To study shifts in the intestinal microbiota during estrus synchronization in ruminants, we characterized the intestinal microbiota in grazing Simmental cows and the possible mechanism that mediates this shift. Fourteen postpartum Simmental beef cows were synchronized beginning on day 0 (D0) with a controlled internal release device (CIDR), and cloprostenol was injected on D9 when the CIDR was withdrawn. Synchronization ended with timed artificial insemination on D12. Serum and rectal samples harvested on D0, D9, and D12 were analyzed to assess the reproductive hormones and microbiota. Reproductive hormones in the serum of the host were measured using enzyme-linked immunosorbent assay. The microbiota was characterized using 16S rRNA sequencing of the V3−V4 hypervariable region, alpha diversity and beta diversity analyses (principal coordinate analysis, PCoA), cladogram of the linear discriminant analysis effect size (LEfSe) analysis, and microbiota function analysis. Levels of the reproductive hormones, except gonadotropin-releasing hormone (p > 0.05), shifted among D0, D9, and D12 (p < 0.05). Decreased community diversity (Chao1 and ACE) was observed on D12 compared with D0 (p < 0.05). The beta diversity (PCoA) of the microbiota shifted markedly among D0, D9, and D12 (p < 0.05). The LEfSe analysis revealed shifts in the intestinal microbiota communities among D0, D9, and D12 (p < 0.05 and LDA cutoff >3.0). The KEGG pathway analysis showed that carbohydrate metabolism, genetic information and processing, the excretory system, cellular processes and signaling, immune system diseases, and the metabolism were altered (p < 0.05). Reproductive hormones (especially estradiol) were correlated with the alpha diversity indices, beta diversity indices, and an abundance of biomarkers of the shifting intestinal microbiota (p < 0.05). In conclusion, the structure, composition, and function of the intestinal microbiota were shifted during estrus synchronization in a grazing Simmental cow model, and these shifts were mediated by reproductive hormones.

Progesterone receptor blockers: historical perspective, mode of function and insights into clinical and scientific applications

Antigestagens (antiprogestins) are functional competitors of progesterone (P4) that prevent P4 from mediating its biological functions either by suppressing its production or blocking its function. Among the latter are progesterone antagonists, competitors of P4 binding to its nuclear receptor PGR, which have found application in both human and veterinary medicine, in particular in small animal practice for the prevention of nidation and the interruption of pregnancy. Depending on their mode of action, progesterone receptor antagonists can be divided into 2 classes. Class I antagonists bind to the PGR but fail to induce its binding to promoters of target genes (competitive inhibitors). Class II antigestagens, including aglepristone used in veterinary medicine, bind to the PGR, activate its association with a promoter, but interfere with the downstream signalling cascades, e. g., by recruiting transcriptional repressors. They act thereby as transdominant repressors exerting negative effects on target gene expression. Importantly for experimental sciences, as active antagonists, class II antagonists do not require the presence of the natural ligand for their action. Besides their clinical application, antigestagens are used in research for investigating P4-dependent physiological and pathological processes. Here an overview of the history and the current usage of progesterone receptor antagonists in veterinary medicine and research is presented.