Comparison of the porcine uterine smooth muscle contractility on days 12-14 of the estrous cycle and pregnancy.

BACKGROUND: Uterine contractile activity is very important for many reproductive functions including embryo transport, implantation, gestation and parturition. Abnormal contractility leads to implantation failure, spontaneous miscarriage, preterm birth and many other disorders. The objective of the present study was to assess the effects of acetylcholine (ACh), noradrenaline (NA), oxytocin (OT) and prostaglandins F2α (PGF2α) and E2 (PGE2) on the contraction of uterine strips collected from the horns of cyclic gilts (12-14 days of the estrous cycle-group I) and from pregnant (12-14 days after first insemination gilts in which one of the uterine horn was gravid (group IIa) and the second one was non-gravid (group IIb). Uterine strips consisting of the endometrium with the myometrium and myometrium alone were examined. RESULTS: ACh increased the tension in all groups as compared to the pretreatment period, and the increase was the highest in group IIb; the amplitude decreased in all groups, and the frequency increased mainly in groups I and IIa. NA did not affect the tension in any group, but decreased the amplitude and frequency in group IIb as compared to groups I and IIa. OT caused the highest increase in the tension in group IIb, a decrease in the amplitude and an increase in the frequency of contractions as compared to the pretreatment period. PGF2α induced the highest increase in the tension and amplitude in group IIb, with a decline in the frequency in this group. PGE2 increased the tension and frequency only in group IIb, and caused the greatest eduction in the amplitude in this group. CONCLUSIONS: These results indicate that contractility of the porcine smooth muscle collected from uterine horns with embryos was different from those obtained from the uterine horns without embryos and the horns of cyclic gilts.

Quantitative expression of lysophosphatidic acid receptor 3 gene in porcine endometrium during the periimplantation period and estrous cycle.

Lysophosphatidic acid (LPA) belongs to the group of lipid messengers, which act via lysophosphatidic acid receptor 3 coupled to G-proteins. The participation of LPA3 in reproductive biology was revealed in mice and has not been studied in gilts. The present study was performed to evaluate the gene expression of LPA3 by a quantitative real-time PCR technique in the endometrium during different stages of pregnancy (days 6-30) and corresponding days of the estrous cycle (days 2-20) as well as in periimplantation period in pigs with surgically detached uterine horns. Based on the most conserved segments of human and rodent LPA3 we obtained a product containing 619bp (GenBank: EF137953), which exhibited high homology with human and rodents sequences. The highest transcript level was noted on days 10-12 of gestation in comparison to remaining periods and during pregnancy on days: 6-7, 8-9, 10-12 and 13-14 in comparison with the corresponding days of the estrous cycle. Higher mRNA level was noted in the horn containing embryos compared to the contralateral horn, where embryos did not develop. The results imply the important role of receptor LPA3 during early pregnancy.