Uterine EMG activity in the non-pregnant sow during estrous cycle

Abstract

BackgroundUterine myoactivity is crucial for successful reproductive performance of the sow. Spontaneous contractions of the uterus are strictly controlled and coordinated. Uterine electromyographic (EMG) activity undergoes hormonal regulation with rapid and long-term effects. What is more, interstitial Cajal-like Cells (ICLC) appear essential for smooth muscle contractility in the reproductive tract where they are suspected to be playing a major role in generating, coordinating, modulating and synchronizing slow triggering waves. The aim of this study was to investigate the myoelectrical activity of sow’s uterus during estrus cycle.ResultsStudy was conducted on 10 Polish Landrace sows. Propagation mechanisms and their connection with the uterine EMG activity were considered in correlation with expression of c-kit, progesterone and oxytocin receptors of the non-pregnant sow. ICLC were labeled with antibody directed against c-kit receptor and visualized by confocal microscopy and scanning cytometer for positive cells percentage assessment. EMG signal was recorded directly from the myometrium with telemetry transmitters and electrodes located in different topographic regions of reproductive tracts. The stages of estrus cycle were determined by monitoring levels of luteinizing hormone, progesterone and estrogen with radioimmunoassays. Significant differences of the EMG signal parameters between diestrus and estrus and the correlations with density of labelled receptors were demonstrated. Moreover, the electrophysiological studies indicated that ICLC in the myometrium in the tip of uterine horn may participate in the regulation of slow waves duration and frequency.ConclusionsThe pattern of EMG signal propagation in the wall of the non-pregnant porcine uterus occurs in an orderly, bidirectional fashion and at distinctive speed, with no differences between diestrus and estrus.

Understanding Sow Sexual Behavior and the Application of the Boar Pheromone to Stimulate Sow Reproduction

“…During estrus, sow myometrial electrical activity and contraction frequency and amplitude increase [12]. Myometrial contractions are regulated by progesterone, oxytocin, and estrogen concentrations [14]. High progesterone reduces uterine contractions whereas high oxytocin and estrogen levels increase them [14].…”

Computational multivariate modelling of electrical activity of the porcine uterus during spontaneous and hormone‐induced oestrus

“…Hence, its elements are zero if the model is Gaussian. Further justification of formulae for higher-order multivariate cumulants, and their meaning, have been described by Domino, Pawlinski et al (2018) and Domino and Gawron (2019).…”

“…Uterine contractions, reflecting a mechanical output of myometrial electrical activity, is crucial in stimulating embryo migration and spacing in the porcine uterus (Geisert & Schmitt, ). Previous research from this laboratory has described the patterns of myoelectrical activity that evolve during different phases of the oestrous cycle (Domino, Pawlinski et al., ; Gajewski et al., ; Pawlinski, Domino, Aniolek, Ziecik, & Gajewski, ). During the oestrous cycle, the ovaries and the uterus experience hormone‐induced physiological changes that are necessary for establishment of pregnancy.…”

“…After ovulation, uterine activity changes in order to assist proper embryo spacing along the uterine horns, facilitating the maternal recognition and establishment of pregnancy (Pope, Maurer, & Stormshak, ). The myometrium undergoes progressive relaxation during the luteal phase, accompanied by myometrial contractions of low amplitude and strength under the influence of progesterone (Domino, Pawlinski et al., ; Mueller et al., ; Pawlinski et al., ). These evolving patterns are consistent with the hypothesis that uterine contractions during oestrus promote fertilization, whereas relaxation facilitates the establishment of pregnancy (Langendijk et al., ; Pusey, Kelly, Bradshaw, & Porter, ; Sammali, Kuijsters, Schoot, Mischi, & Rabotti, ).…”

“…The surge in luteinizing hormone (LH) at the end of the follicular phase is responsible for ovulation and release of mature oocytes and facilitates sperm transport through the horns of the uterus towards the distal end of the oviduct, where fertilization takes place (Langendijk, Soede, & Kemp, 2005). There is a progressive increase in the amplitude and strength of contractions in both the uterus and the oviduct during this period (Domino, Pawlinski et al, 2018;Pawlinski et al, 2016). After ovulation, uterine activity changes in order to assist proper embryo spacing along the uterine horns, facilitating the maternal recognition and establishment of pregnancy (Pope, Maurer, & Stormshak, 1982).…”