Angiotensin II and Atrial Natriuretic Peptide in the Cow Oviductal Contraction In Vitro: Direct Effect and Local Secretion of Prostaglandins, Endothelin-1, and Angiotensin II

Abstract

Angiotensin II (Ang II) and atrial natriuretic peptide (ANP) may be involved in local regulation of the oviductal contraction during the estrous cycle. Thus, the in vitro effects of Ang II and ANP on the secretion and contraction of bovine oviduct during the follicular, postovulatory, and luteal phases were investigated. An in vitro microdialysis system (MDS) was utilized to determine the intraluminal release of prostaglandins (PGs), Ang II, and endothelin-1 (ET-1) from the bovine oviducts as well as to observe the effect of Ang II and ANP on the local secretion of these substances. The basal release of PGs, ET-1, and Ang II was higher (P < 0.05) during the follicular and postovulatory phases than during the luteal phase. Stimulation by infusion of Ang II (10(-6) M) or ANP (10(-7) M) into the MDS was carried out for 4 h between 4 and 8 h of incubation. In the oviducts from the follicular and postovulatory phases, the infusion of ANP increased the release of Ang II, but not of ET-1. Infusion of Ang II stimulated the release of ET-1. Both Ang II and ANP increased PGE(2) and PGF(2alpha) release. In the contraction study, direct administration of Ang II (10(-7) M) or ANP (10(-8) M) into the medium during the follicular and postovulatory phases increased the amplitude of oviductal contraction. In contrast, these substances did not show any effect in the contraction and secretion of oviducts from cows during the midluteal phase. These results indicate that during the periovulatory period, Ang II and ANP stimulate the contractile amplitude of the oviduct in vitro. In addition to their direct action on oviductal contraction, Ang II may activate oviductal secretion of ET-1 and PGs. Likewise, ANP stimulates oviductal secretion of PGs and Ang II. Hence, the overall results suggest the existence of a functional endothelin-angiotensin-ANP system in the bovine oviduct during the periovulatory period, which may regulate the oviductal contraction to ensure maximum efficiency of gamete/embryo transport through the oviduct.

Angiotensin II Secretion by the Bovine Oviduct is Stimulated by Luteinizing Hormone and Ovarian Steroids

“…Moreover, luteinizing hormone (LH) stimulates e production and release of these hormones by the bovine oviduct during this period, and estradiol-17β (E2) exerts a synergistical effect on this LH action [11]. Thus, it has been speculated that Ang II production is stimulated by LH and ovarian steroids in the regulation of the peak oviductal contractions responsible for rapid gamete transport to the fertilization site [6].The Ang II concentration increases dramatically in the ovarian venous plasma after the LH surge, [12] and follicular Ang II rises during the LH surge [12]. Moreover, E2 increases Ang II production in microvascular endothelial cells from the bovine corpus luteum in vitro [13] and induces Ang II-R expression in bovine thecal cells [14].…”

“…Moreover, our recent reports revealed that TNFα [7,8], VEGF [29] and atrial natriuretic peptide (ANP) [6] stimulates the production and release of PGE2, PGF2α and ET-1in the bovine oviduct [7,8,11,29]. Also, Ang II stimulate PGE2, PGF2α and ET-1 release [6]. Thus, Ang II appears to be a local mediator for TNFα, VEGF and ANP to stimulate PGE2, PGF2α and ET-1 release from the oviduct, in addition to acting directly on oviductal smooth muscle [11].…”

“…Expression of Ang II and Ang II receptor (Ang II-R) in the human fallopian tube has been demonstrated [4], and Ang II plays a role in regulating the composition of fallopian tube secretions [5]. We recently reported that Ang II is secreted by the bovine oviduct and stimulates oviductal contractions [6][7][8]. Indeed, in the bovine oviduct, Ang II stimulates release of prostaglandin E2 (PGE2), prostaglandin F2α (PGF2α), and endothelin-1 (ET-1), which are the predominant inducers of contractions [9][10][11].…”

“…Moreover, luteinizing hormone (LH) stimulates e production and release of these hormones by the bovine oviduct during this period, and estradiol-17β (E2) exerts a synergistical effect on this LH action [11]. Thus, it has been speculated that Ang II production is stimulated by LH and ovarian steroids in the regulation of the peak oviductal contractions responsible for rapid gamete transport to the fertilization site [6].…”

N-acetylglucosaminyltransferase I Activity of Bovine Oviduct Epithelial Cells: Stimulation by Luteinizing Hormone, Vascular Endothelial Growth Factor and Tumor Necrosis Factor .ALPHA.

“…Moreover, several studies have revealed that the preovulatory surge of luteinizing hormone (LH) activates maximum bovine oviductal secretion and contraction [8][9][10][11][12]. Thus, LH may directly stimu late the release of soluble ovid uctal glycosyltransferases, increasing glycosylation and thereby providing the best environment for fertilization, gamete/embryo survival and development.…”