Sex chromosome complement and organizational hormonal effects on the vasopressinergic sexual dimorphic pressor and antidiuretic responses

Abstract

Abstract The present study aimed to analyze the role of the sex chromosomes (SCC:XX/XY) and the interaction with the organizational effects of gonadal steroids on the vasopressinergic sexually dimorphic antidiuretic and pressor responses. For this purpose, we used transgenic mice of the "four core genotypes" model, in which the effect of gonadal sex and SCC are dissociated. To study vasopressin dimorphism in the antidiuretic response, mice were gonadectomized at 60 days old, and six weeks later were subcutaneously injected with desmopressin (V2R agonist, 1 mg/kg) and vehicle solution (isotonic saline solution). Four hour later urine samples were obtained for urinary osmolality determination. In a different group of animals, kidneys were excised for Avpr2 mRNA evaluation by qPCR. We also evaluated changes in blood pressure and heart rate in anesthetized mice in response to a 30-minute vasopressin (0.2 UI/ml, infusion volume 100µl) continuous infusion. As expected, desmopressin administration induced a significant effect of treatment {F(1,37) = 439,63}, however no SCC nor organizational hormonal effects were observed in absence of the activational hormonal effects. Furthermore, no differences in Avpr2 mRNA levels were found. However, the statistical analysis of the percentage changes in mean arterial pressure due to continuous acute vasopressin infusion demonstrated an interaction between the organizational hormonal effect and SCC {F(6,144) = 3,891, p = 0,0012}. Male mice with XX-SCC background showed a greater pressor response than the other genotypes. Our data may contribute to the understanding in hydromineral and blood pressure regulation of the complex interplay between vasopressin and SCC/organizational hormonal backgrounds.