Modulatory effect of three antibiotics on uterus bovine contractility in vitro and likely therapeutic approaches in reproduction

This in vitro study investigates the modulatory effect of three antibiotics (amoxicillin, enrofloxacin, and rifaximin) on contractility of the bovine uterine tissue in follicular and luteal phases. The effects of these antibiotics at three single doses (10⁻⁶, 10⁻⁵, and 10⁻⁴ M) on their basal contractility were evaluated in isolated organ bath. The functionality of the strip throughout the experiment was evaluated by a dose of carbachol (10⁻⁵ M); the obtained effect had to be repeatable (difference of ≤20%) that is comparable to that induced by the previous administration of the same substance. The results demonstrate the different modulatory activities of these antibiotics on uterine contractility in follicular and luteal phases. The effects induced by amoxicillin and enrofloxacin are opposite: the first relaxes and the second increases the uterine contractility in both cycle phases. Instead, the activity of rifaximin varies depending on the phase of estrous cycle: it increases in the follicular phase and relaxes in the luteal phase. The obtained data provide the hypothesis of possible implications of these drugs in the pharmacologic modulation of uterine contractions. Their action at this level, associated with their specific antimicrobial effects, could suggest using these antibiotics for the treatment of diseases related to postpartum or infections that may occur in pregnant cattle, by virtue of their effects on myometrial contractility too.