Expression of the oxytocin and V1a vasopressin receptors in human myometrium in differing physiologic states and following misoprostol administration

Assessment of the perioperative effect of vasopressin in patients undergoing laparoscopic myomectomy: A double-blind randomised study

Background and Aims:

Myomectomy is associated with perioperative bleeding. The aim of the study is to evaluate the effect of intramyometrial vasopressin on blood loss and the associated cardiovascular complications during myomectomy.

Methods:

The study included 194 patients classified into two groups- 1) Vasopressin group: the vasopressin was diluted as 0.1 unit/ml and 15 ml was injected by the surgeon in the plane between the myometrium and the myoma. 2) Control group: The patients received an equal amount of normal saline. The monitored parameters included the amount of blood loss, required blood transfusion, heart rate, mean arterial blood pressure, the incidence of hypertension, hypotension, bradycardia, tachycardia, electrocardiogram (ECG) changes and the blood troponin I level.

Results:

The heart rate decreased significantly in both groups, but the decrease was lower with vasopressin than the control group through the time points T3 to T5 (P < 0.05) The mean arterial blood pressure increased significantly in both groups, but the increase was higher with vasopressin than the control group through T3 to T5 (P < 0.05). The amount of blood loss decreased significantly with vasopressin than the control groups (P = 0.001). The number of transfused packed red blood cells was lower with vasopressin than the control group (P = 0.001). The incidence of hypertension, bradycardia and atrial extrasystole was higher with vasopressin than the control group (P = 0.005, P = 0.012, P = 0.033, respectively).

Conclusion:

Intramyometrial vasopressin decreases blood loss and blood transfusion, but it is associated with cardiovascular complications that may be serious as reported in other studies. Therefore, anaesthesiologists and gynaecologists must follow the precautions to avoid and minimise the incidence of complications with intramyometrial vasopressin.

Oxytocin in the Male Reproductive Tract; The Therapeutic Potential of Oxytocin-Agonists and-Antagonists

In this review, the role of oxytocin and oxytocin-like agents (acting via the oxytocin receptor and belonging to the oxytocin-family) in the male reproductive tract is considered. Previous research (dating back over 60 years) is revised and connected with recently found aspects of the role oxytocin plays in male reproductive health. The local expression of oxytocin and its receptor in the male reproductive tract of different species is summarized. Colocalization and possible crosstalk to other agents and receptors and their resulting effects are discussed. The role of the newly reported oxytocin focused signaling pathways in the male reproductive tract, other than mediating contractility, is critically examined. The structure and effect of the most promising oxytocin-agonists and -antagonists are reviewed for their potential in treating male disorders with origins in the male reproductive tract such as prostate diseases and ejaculatory disorders.

Critical role of V1a vasopressin receptor in murine parturition†

The precise mechanisms of the reproductive physiological processes, such as labor initiation, are poorly understood. Oxytocin (OT) is one of the well-known uterotonics and is clinically adopted as a medication to facilitate childbirth. Vasopressin (VP), a posterior pituitary hormone similar to OT, has also been proposed to be involved in the reproductive physiology. In this study, we found that a total deficiency of V1a receptor subtype (V1aR) in mice resulted in a reduced number of pups, delayed labor initiation, and increased post-delivery hemorrhage compared with those in wild-type mice. Among the VP receptor subtypes, only V1aR was found to be expressed in the murine uterus, and its distribution pattern was different from that of the oxytocin receptor (OTR); V1aR expression was mainly distributed in the circular myometrium, whereas OTR was strongly expressed in both the circular and longitudinal myometrium. The maximum contractile force of the circular myometrium, induced by VP or OT, was attenuated in the pregnant uterus of Avpr1a-deficient mice. Contrarily, while OT expression was decreased in the Avpr1a-deficient uterus, OTR expression was significantly increased. These results suggest that V1aR deficiency not only reduces the uterine contractile force but also perturbs the expression of genes responsible for the reproductive physiology. Therefore, V1aR is necessary to exert the maximum contraction of the circular myometrium to deliver pups. This study revealed an important role of V1aR in physiological contraction and term parturition in mice.

Influence of oxytocin receptor single nucleotide sequence variants on contractility of human myometrium: an in vitro functional study

Background

Oxytocin receptor (OXTR) gene variants have been shown to affect the prevalence of preterm birth, mode of delivery and oxytocin (OXT) requirements for labor induction and augmentation. We hypothesized that this might be associated with different myometrium responses to oxytocin. Our aim was to investigate the influence of a selection of eight OXTR gene single nucleotide variants on oxytocin-induced stimulation of human myometrium contractility in vitro.

Methods

Human myometrium biopsies were collected during elective cesarean sections at term, if patients had given informed consent. Myometrial strips were submerged under tension in an organ bath and allowed to contract; the remaining material was stored at − 80 °C for further determination of relevant genetics and mRNA level. The area under the curve (AUC) of all contractions taking place in the absence of OXT and of those occurring upon OXT addition (for 30 min each) was measured. OXT stimulation, defined as the ratio between AUC measurements after OXT addition and those in the absence of OXT was calculated for each strip. TaqMan™ Assays were used to detect the allele distribution of the eight OXTR variants and to determine the relative amounts of OXTR-mRNA in the samples. For each variant, oxytocin stimulation of contractility was compared between samples homozygous for the reference allele (reference group) and samples with at least one variant allele (variant group) by linear regression.

Results

Sixty samples were included in the present study. For rs1042778, rs11706648, rs4686301, rs53576, rs237895, and rs237902, OXT stimulation was similar in the reference and in the variant groups. However, the values of OXT stimulation differed significantly between the reference and the variant groups for rs4686302 (3.1 vs. 4.1 times; p = 0.022) and rs237888 (3.2 vs. 5.5 times; p = 0.001). No significant differences between the levels of OXTR-mRNA in the various reference and corresponding variant groups were detected.

Conclusions

Patients with variant alleles of rs237888 and/or rs4686302 may be more sensitive to oxytocin stimulation, explaining why these sequence variants have been associated with lower cesarean section prevalence and premature birth, respectively.

Perioperative Interventions to Minimize Blood Loss at the Time of Hysterectomy for Uterine Leiomyomas: A Systematic Review and Meta-analysis

STUDY OBJECTIVE

Hysterectomy for uterine leiomyoma(s) is associated with significant morbidity including blood loss. A systematic review and meta-analysis was conducted to identify nonhormonal interventions, perioperative surgical interventions, and devices to minimize blood loss at the time of hysterectomy for leiomyoma.

DATA SOURCES

Librarian-led search of Embase, MEDLINE, Web of Science, Scopus, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases from 1946 to 2018 with hand-guided updates.

METHODS OF STUDY SELECTION

Included studies reported on keywords of hysterectomy, leiomyoma, and operative blood loss/postoperative hemorrhage/uterine bleeding/metrorrhagia/hematoma. The review excluded a comparison of route of hysterectomy, morcellation, vaginal cuff closure, hormonal medications, vessel sealing devices for vaginal hysterectomy, and case series with <10 patients.

TABULATION, INTEGRATION, AND RESULTS

Surgical blood loss, postoperative hemoglobin (Hb) drop, hemorrhage, transfusion, and major and minor complications were analyzed and aggregated in meta-analyses for comparable studies in each category. A total of 2016 unique studies were identified, 33 of which met the inclusion criteria, and 22 were used for quantitative synthesis. The perioperative use of misoprostol in abdominal hysterectomy (AH) was associated with a lower postoperative Hb drop (0.59 g/dL; 95% confidence interval [CI], 0.39-0.79; p < .01) and blood loss (-96.43 mL; 95% CI, -153.52 to -39.34; p < .01) compared with placebo. Securing the uterine vessels at their origin in laparoscopic hysterectomy (LH) was associated with decreased intraoperative blood loss (-69.07 mL; 95% CI, -135.20 to -2.95; p = .04) but no significant change in postoperative Hb (0.24 g/dL; 95% CI, -0.31 to 0.78; p = .39) compared with securing them by the uterine isthmus. Uterine artery ligation in LH before dissecting the ovarian/utero-ovarian vessels was associated with lower surgical blood loss compared with standard ligation (-27.72 mL; 95% CI, -35.07 to -20.38; p < .01). The postoperative Hb drop was not significantly different with a bipolar electrosurgical device versus suturing in AH (0.26 g/dL; 95% CI, -0.19 to 0.71; p = .26). There was no significant difference between an electrosurgical bipolar vessel sealer (EBVS) and conventional bipolar electrosurgical devices in the Hb drop (0.02 g/dL; 95% CI, -0.15 to 0.20; p = .79) or blood loss (-50.88 mL; 95% CI, -106.44 to 4.68; p = .07) in LH. Blood loss in LH was not decreased with the LigaSure (Medtronic, Minneapolis, MN) impedance monitoring EBVS compared with competing EBVS systems monitoring impedance or temperature (2.00 mL; 95% CI, -8.09 to 12.09; p = .70). No significant differences in hemorrhage, transfusion, or major complications were noted for all interventions.

CONCLUSION

Perioperative misoprostol in AH led to a reduction in surgical blood loss and postoperative Hb drop (moderate level of evidence by Grading of Recommendations, Assessment, Development and Evaluation guidelines) although the clinical benefit is likely limited. Remaining interventions, although promising, had at best low-quality evidence to support their use at this time. Larger and rigorously designed randomized trials are needed to establish the optimal set of perioperative interventions for use in hysterectomy for leiomyomas.