Objective: Investigating of the possible effects of melatonin analog, agomelatine, on spontaneous and oxytocin-induced contractility of rat myometrium in vitro.

Materials and Methods: In this study myometrium strips were removed from female Spraque-Dawley rats in dioestrus and placed in a isolated tissue bath containing Krebs solution. Effects of agomelatine (50 μM, 100 μM and 200 μM concentrations) on spontaneous and oxytocin-induced miyometrium contractions were studied. Luzindole, the melatonin receptor antagonist, was also used before the application of the agomelatine to determine whether action of agomelatine was melatonin receptor-mediated.

Results: Agomelatine inhibited spontaneous and oxytocin-induced contractions of rats myometrium in a dose-dependent manner. After application of luzindole, inhibition was not reversed.

Conclusions: In this study the inhibitor effect of agomelatine on spontaneous and oxytocin-induced uterine contractility in rats was shown for the first time. This inhibitor effect of agomelatine may provide an advantage in inhibiting uterine contractions in pregnant women with abortion risk. After administration of the melatonin receptor antagonist luzindol, the inhibition does not reverse, indicating that agomelatine was not bound to melatonin receptors. These results support that agomelatin may have a potential to modulate myometrial function.