In vitro regulation of local secretion and contraction of the bovine oviduct: stimulation by luteinizing hormone, endothelin-1 and prostaglandins, and inhibition by oxytocin

Abstract

The precise regulatory mechanisms of cyclic oviductal contraction in the cow are unclear. The purpose of this study was to evaluate the effect of luteinizing hormone (LH), steroids, prostaglandins (PGs) and peptides on the oviductal contraction and secretion of PGs and endothelin (ET-1). In addition, the cyclic expression of mRNA for ET-1 and its receptors (ET-R) was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). In the in vitro microdialysis study, an infusion of LH alone or in combination with progesterone (P 4 ), estradiol-17 (E 2 ) and/or ET-1 stimulated pronounced release of PGE 2 , PGF 2 and ET-1 in the oviducts from cows in the follicular and postovulatory phases. The addition of LH, LH+P 4 +E 2 and/or ET-1 to the medium increased the amplitude of oviductal contraction. However, oxytocin (OT) completely blocked the responses of oviductal secretion and contraction. In contrast, these substances did not show any effect in the oviducts from cows in the mid luteal phase. Similar expression patterns of mRNA encoding for ET-R type A and type B were found, which were highest during the postovulatory phase, lower during the luteal phase, with the lowest expression during the follicular phase. We suggest that the preovulatory LH surge, together with increasing E 2 levels from the Graafian follicle and a basal P 4 from regressing corpora lutea (CL), stimulates maximum oviductal production of PG and ET-1, resulting in oviductal contraction for a rapid transport of gametes. OT released from the newly-formed CL may block these mechanisms, and slow contractions for transport of the embryo to the uterus.

Oviduct: roles in fertilization and early embryo development

“…Additionally, E 2 , P 4 and endothelin-1 stimulate the release of PGs (PGE 2 and PGF 2α ) in bovine oviduct (Wijayagunawardane et al 2001). Both PGE 2 and PGF 2α are shown to stimulate muscle contraction in human and bovine oviducts (Wijayagunawardane et al 2001, Wanggren et al 2008. Endothelin-2 alone can also induce muscle contraction in the rat oviduct through endothelin receptor type A (Al-Alem et al 2007).…”

Summer heat stress affects prostaglandin synthesis in the bovine oviduct

“…Prostaglandin (PG) E 2 and PGF 2a concentrations in the oviduct ipsilateral to the corpus luteum (CL) or the dominant follicle are highest in the periovulatory phase (Wijayagunawardane et al 1998). These PGs seem to control gamete/embryo transport by stimulating smooth muscle motility (Wijayagunawardane et al 2001).…”

Regulation of bovine oviductal NO synthesis by follicular steroids and prostaglandins

“…Various molecules regulate the motility of oviductal smooth muscle. Contraction is induced by PGF2α, endothelins, angiotensin II, and E2 (Helm et al 1982, Wijayagunawardane et al 2001a,b, Siemieniuch et al 2009), whereas relaxation is induced by NO, PGE2, luteinizing hormone, and P4 (Helm et al 1982, Rosselli et al 1994, Gawronska et al 1999, Siemieniuch et al 2009). Some of these molecules are secreted by the oviductal epithelium (Rosselli et al 1994, Wijayagunawardane et al 2009, Szóstek et al 2011, contributing to activate the motility of the oviductal smooth muscle around the time of ovulation.…”