Adrenergic inhibition of uterine contractions and oviposition in the lizard Anolis carolinensis.

Injection of arginine vasotocin (AVT), which induces oviposition in several lizard species, fails to do so in Anolis carolinensis. We tested the hypothesis that epinephrine-induced activation of beta-adrenoreceptors in the uterus inhibits AVT action on uterine smooth muscle. Pretreatment of gravid females with the beta-adrenoreceptor antagonist dichloroisoproterenol 15 min before an AVT injection resulted in uterine sensitivity to AVT and subsequent oviposition. Furthermore, in vitro tests indicated that epinephrine as well as a beta-adrenoreceptor agonist (isoproterenol) inhibit uterine tonic and rhythmic contractions that normally follow exposure to AVT. These results suggest that stress-induced secretion of epinephrine can act as a short-term inhibitor of oviposition in this species.