Abstract
BackgroundUterine 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.ResultsACh 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.ConclusionsThese 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.
Highlights
Uterine contractile activity is very important for many reproductive functions including embryo transport, implantation, gestation and parturition
The aim of our study was to examine the effects of ACh, OT, prostaglandins F2α (PGF2α), and PGE2 on the contraction of uterine strips collected from the horns of cyclic gilts and from the horns with and without embryos of early pregnant pigs
Summarizing, ACh, OT, PGF2α and PGE2 significantly increased the tension and decreased the amplitude of contraction in gravid horns compared to non-gravid horns and cyclic gilts
Summary
Uterine contractile activity is very important for many reproductive functions including embryo transport, implantation, gestation and parturition. Contractions and relaxations of the porcine myometrium are controlled by the autonomic nerve system [1]. It is generally accepted that OT stimulates uterine contractile activity via its receptors [6], which are present in the porcine uterus [16]. Oxytocin, acting through its receptors in the endometrium and myometrium, is involved in the control of PGF2α and PGE2 secretion in pigs [17, 18]. The direct action of PGF2α on contractile (FP, EP1, EP3) and relaxatory (DP, IP, EP2) receptors in porcine uterine smooth muscle has been described [2]. PGE2 may cause contraction or relaxation through its impact on particular EP receptor subtypes [10]
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