A comparison of uterine contractile responsiveness to arginine vasopressin in oviparous and viviparous lizards

AbstractNonapeptides and their receptors regulate a diverse range of physiological processes. We assessed the contractile responsiveness of uteri from the squamate viviparous-oviparous species pair,Pseudemoia entrecasteauxii andLampropholis guichenoti, as well as the bimodally reproductive species,Saiphos equalis, to arginine vasopressin (AVP). We assessed the resulting uterine contractility as a function of pregnancy status, species and parity mode. We also measured mRNA abundance for the nonapeptide receptor, oxytocin receptor (oxtr), in uteri fromP. entrecasteauxii andL. guichenoti and compared expression across pregnancy status and parity mode. We found that pregnant uteri exhibited a significantly greater contractile response to AVP than non-pregnant uteri in all three lizard species studied. Cross-species comparisons revealed that uteri from viviparousP. entrecasteauxii were significantly more responsive to AVP than uteri from oviparousL. guichenoti during both pregnant and non-pregnant states. Conversely, for non-pregnantS. equalis, uteri from viviparous individuals were significantly less responsive to AVP than uteri from oviparous individuals, while during pregnancy, there was no difference in AVP contractile responsiveness. There was no difference in expression ofoxtr betweenL. guichenoti andP. entrecasteauxii, or between pregnant and non-pregnant individuals within each species. We found no significant correlation betweenoxtr expression and AVP contractile responsi...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - Category: Physiology Source Type: research