TOCOLYTIC EFFECT OF PARECOXIB, A NEW PARENTERAL CYCLO-OXYGENASE-2-SPECIFIC INHIBITOR, ON THE SPONTANEOUS AND PROSTAGLANDIN-INDUCED CONTRACTIONS OF RAT ISOLATED MYOMETRIUM

Investigation of Effects of Gadolinium-Based Contrast Agents on Uterine Contractility Using Isolated Rat Myometrium

BACKGROUND

Despite concerns about safety, gadolinium-based contrast agents (GBCAs) are still used for abdominal and pelvic imaging during pregnancy. Researchers have mainly focused on teratogenicity, while very little is known about their possible direct effects on uterine contractility, yet free gadolinium potentially impacts contractility through interaction with calcium channels.

PURPOSE

To investigate possible effects of selected GBCAs (namely gadoteridol, gadoversetamide, gadobutrol, gadoterate meglumine, and gadoxetic acid) on the contractility of rat myometrium.

STUDY TYPE

In vitro organ bath study.

ANIMAL MODEL

Myometria were isolated from adult (10-12 weeks old) Sprague Dawley rats, both pregnant (N = 8) and nonpregnant (N = 36).

FIELD STRENGTH/SEQUENCE

NA.

ASSESSMENT

Myometrial strips were suspended in tissue bath containing physiological saline and isometric contractions were recorded. GBCAs were added to the tissue bath cumulatively, and their effects on contractility parameters (quantified by amplitude, frequency, and area under contractility curve [AUC]) were evaluated by 10-minute intervals.

STATISTICAL TESTS

Normality data, checked by Shapiro-Wilk test, were transformed by arcsine when needed. One- or two-way analysis of variance was performed, where appropriate, followed by Student-Newman-Keuls test. A P value of <0.05 was considered statistically significant.

RESULTS

All of the assayed GBCAs elicited some alterations in the myometrial contractility in a concentration-dependent manner. Gadoterate meglumine, gadoxetic acid, and gadoversetamide caused a concentration-dependent significant attenuation in AUC (oxytocin-induced, from 100% during control period to 45.1 ± 9.0% (nonpregnant) and 59.9 ± 8.5% (pregnant), for 90 μM gadoterate meglumine; respectively), and frequency of the spontaneous and oxytocin-induced contractions. Gadobutrol and gadoteridol at highest dose significantly attenuated mean AUC and frequency of oxytocin-induced contractions of nonpregnant myometrium.

DATA CONCLUSION

Results from this in vitro study indicate that GBCAs elicit modulation of myometrial contractions at clinically relevant concentrations. These effects may account, at least partially, for the known potential side effects (rare cases of miscarriages and elective abortion) of these agents.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 5.

Ovarian hyperstimulation syndrome inhibition by targeting VEGF, COX-2 and calcium pathways: a preclinical randomized study

OBJECTIVE

The efficacy of vascular endothelial growth factor (VEGF), COX-2, calcium and aromatase inhibitors in an ovarian hyperstimulation syndrome (OHSS) rat model was tested.

METHODS

One hundred and eight female Wistar rats were randomly divided in nine groups. The control group received saline, while the OHSS group received rec-FSH for 4 consecutive days. The other seven groups received rec-FSH (4d) and Bevacizumab twice, Parecoxib daily, Verapamil daily, Parecoxib daily and Bevacizumab twice, Verapamil daily and Bevacizumab twice, Parecoxib and Verapamil daily, Letrozole and Meloxicam daily, respectively. All groups received also hCG at the 5th day.

RESULTS

All intervention groups were characterized by reduced vascular permeability compared to the OHSS group, which in the groups of Verapamil (Calcium inhibition) and Parecoxib + Verapamil (COX-2 + Calcium inhibition) presented significant statistical difference. The Verapamil group showed the lowest corpus luteum formation, while the Parecoxib (COX-2 inhibition), the Parecoxib + Verapamil (COX-2 + Calcium inhibition), the Bevacizumab + Parecoxib (VEGF + COX-2 inhibition) and the Bevacizumab + Verapamil (VEGF + Calcium inhibition) groups were also characterized by lower corpus luteum numbers compared to the OHSS group. Furthermore, lower graafian follicle formation was observed in the above groups, while the ovarian weight and the hormonal profile were not significantly affected.

CONCLUSIONS

Studying the different check points of the VEGF pathway, we conclude that targeting calcium pathways could be beneficial for the vascular permeability control in an OHSS animal model.

Complex effects of imatinib on spontaneous and oxytocin-induced contractions in human non-pregnant myometrium

Human myometrium includes two important cell populations involved in its contractility: smooth muscle fibers and interstitial cells. The pacemaking mechanism is not yet identified, but it is possible that myometrial smooth muscle cells contract in response to a signal generated by c-kit positive interstitial cells. The aim of this study was to investigate the effects of imatinib as a c-kit receptor antagonist on the spontaneous or oxytocin (OT) induced contractions of human non-pregnant myometrium in vitro. Myometrial strips were obtained from non-pregnant women (reproductive age) undergoing hysterectomy for benign indications. The strips were suspended in organ baths for recording of isometric tension. Imatinib effects were assessed on spontaneous contraction and after preexposure to OT.Direct exposure of myometrial strips to imatinib inhibits both amplitude and frequency of contractions (80-320 μM) in a dose dependent manner. Amplitude reverted back to 90% of the baseline amplitude by consequent addition of imatinib (until 480 μM). Total inhibition of myometrial contraction was obtained after addition of OT 60 nM. If myometrium was pre-exposed to OT (320 nM), imatinib 80-160 μm increased amplitude, while decreasing frequency. These data provide evidence that telocytes may be involved as modulators of the spontaneous contractions of the non-pregnant human uterus, via a tyrosine-kinase independent signaling pathway.