Effect of fixed-time artificial insemination on corpus luteum gene expression at the day 16 and 25 pregnancy of gilt

Development of highly bioactive long-acting recombinant porcine FSH for batch production management of sows

To improve the economic benefits, exogenous hormones are used to control follicular development and synchronize ovulation in the batch flow management of gilts and weaned sows. Equine chorionic gonadotropin (eCG) is widely used to stimulate follicular development in both experimental and farm animals. Despite its effectiveness, several side effects have been found, including the occurrence of follicular cysts, follicular premature luteinization, and increased follicular atresia. As eCG is a heterologous protein, the generation of antibodies has been found in the superovulation of cattle. Moreover, the extraction of eCG from pregnant mare serum raises concerns regarding animal welfare, as well as potential risks for disease transmission. Follicle stimulating hormone (FSH) controls the follicular growth and maturation in the porcine ovary under physiological conditions. In the current study, we developed a novel long-acting recombinant porcine FSH (rpFSH-pFc) consisting of porcine FSH and porcine fragment crystallizable (Fc) via (G4S)3 linker by using the available protein fusion technology to control the follicular development and maturation. The results of pharmacokinetic studies indicated that rpFSH-pFc exhibited a prolonged half-life in both rats and sows. The efficacy of rpFSH-pFc was confirmed by cAMP level evaluation and germinal vesicle breakdown (GVBD) analysis in vitro. Through ovarian weight gain, superovulation and fertility testing assays, our results revealed that a single rpFSH-pFc treatment could effectively promote follicular development and maturation in vivo. Meanwhile, the mRNA expression levels of the target genes associated with follicular development, maturation and ovulation were significantly up-regulated after rpFSH-pFc treatment. Taken together, our results revealed that rpFSH-pFc could bind to the FSH receptor, stimulate follicular growth and development in female mice, and possess a prolonged half-life in both rats and sows. These characteristics suggest that rpFSH-pFc may be an ideal candidate for promoting follicular growth and development in livestock production.

Porcine reproductive and respiratory syndrome virus infects the reproductive system of male piglets and impairs development of the blood-testis barrier

Porcine reproductive and respiratory syndrome virus (PRRSV) causes a highly contagious disease that threatens the global swine industry. Recent studies have focused on the damage that PRRSV causes to the reproductive system of male pigs, although pathological research is lacking. Therefore, we examined the pathogenic mechanisms in male piglets infected with PRRSV. Gross and histopathological changes indicated that PRRSV affected the entire reproductive system, as confirmed via immunohistochemical analysis. PRRSV infected Sertoli cells and spermatogonia. To test the new hypothesis that PRRSV infection in piglets impairs blood - testis barrier (BTB) development, we investigated the pathology of PRRSV damage in the BTB. PRRSV infection significantly decreased the quantity and proliferative capacity of Sertoli cells constituting the BTB. Zonula occludens-1 and β-catenin were downregulated in cell - cell junctions. Transcriptome analysis revealed that several crucial genes and signalling pathways involved in the growth and development of Leydig cells, Sertoli cells, and tight junctions in the testes were downregulated. Apoptosis, necroptosis, inflammatory, and oxidative stress-related pathways were activated, whereas hormone secretion-related pathways were inhibited. Many Sertoli cells and spermatogonia underwent apoptosis during early differentiation. Infected piglets exhibited disrupted androgen secretion, leading to significantly reduced testosterone and anti-Müllerian hormone levels. A cytokine storm occurred, notably upregulating cytokines such as tumour necrosis factor-α and interleukin-6. Markers of oxidative-stress damage (i.e. H2O2, malondialdehyde, and glutathione) were upregulated, whereas antioxidant-enzyme activities (i.e. superoxide dismutase, total antioxidant capacity, and catalase) were downregulated. Our results demonstrated that PRRSV infected multiple organs in the male reproductive system, which impaired growth in the BTB.

MicroRNAs are potential regulators of the timed artificial insemination effect in gilt endometrium

To determine effects of timed artificial insemination (TAI) hormonal treatments on reproductive performance of gilts/sows and explore molecular mechanisms, gilts (TAI: 90; Control:149; Total: 239) and sows (TAI: 370; Control: 492) were utilized. Results indicated the estrus/farrowing rate and number of piglets born alive and weaned in the TAI group were greater than in the control group for both gilts and sows. To explore the molecular mechanism for TAI hormonal effects, the small RNA of the gilt endometrium at 16 and 25 of gestation were sampled and sequenced to determine potential functions of microRNA (MiRNA); 358 known and 142 novel MiRNAs were detected. With comparison of TAI and control groups, there were 54 differentially abundant MiRNAs, and functional analysis results indicated "binding," "protein/ion binding," and "immune response" were mostly enriched. In addition, representative MiRNAs were selected based on criteria including being regulated on both day 16 and 25 of gestation (ssc-miR-10a-5p, ssc-miR-345-5p, ssc-miR-370) along with reproduction-related target genes (ssc-miR-424-5p, ssc-miR-142-5p). Furthermore, target genes of selected MiRNAs were screened, and functional enrichment of those genes also indicated that the "binding" and "immune response" were mainly enriched. Results from the present study confirmed TAI-hormonal treatments improved estrous/farrowing rate and number of piglets born alive/weaned of gilts/sows and that hormonal treatment regimens leading to behavioral estrus at timed artificial insemination in gilts results in microRNA patterns in the endometrium that are more supportive of pregnancy. Results contribute valuable information for future studies of effects of TAI hormonal treatments on pig reproductive performance.