Influence of embryonic conditioned media upon the endometrial beta-adrenergic receptor.

The main objective of this study was to evaluate the influence of the products secreted by the human embryo upon the three subtypes of beta-AR (beta1, beta2, beta3). Cell cultures were developed using endometrial biopsies, taken on day 7 after ovulation, from four healthy women <35 years of age, with regular cycles and infertility due only to male factors. Embryos from women with a normal uterine cavity and endometrial lining were incubated until they reached the 4-cell stage, before being transferred to their mother's uterus. Culture media for embryo incubation were derived from two groups: (i) embryos that achieved pregnancy, (ii) embryos which failed to implant. Control and experimental endometrial cell culture plates were treated with the two embryo culture media, with or without 10(-9) mol/l oestradiol and 10(-7) mol/l progesterone for 48 h. Expression of the three subtypes of beta-AR was assessed by RT-PCR. Beta1-AR was expressed in both control and experimental plates; beta2-AR was expressed only in plates incubated with embryonic culture media of embryos which achieved pregnancy, in both hormonal conditions, with or without oestradiol and progesterone. Beta3-AR was not expressed in any condition. Thus secretory products of human embryos may influence gene expression of beta2-AR concentrations in the human endometrium, and this subtype of beta-AR may be involved in implantation.

Influence of the estrous cycle on the norepinephrine-induced contraction of rat aorta: relationship to vascular prostanoids biosynthesis.

Since ovarian sex steroids (estradiol and progesterone) may affect both blood pressure and prostanoids synthesis, and because prostaglandin-E2 (PGE2) and prostacyclin (PGI2) can modulate the vascular action of pressor hormones, we investigated the vascular reactivity to norepinephrine during the estrous cycle of the rat. In addition, we determined the vascular biosynthesis of PGE2 and 6-keto-PGF1 alpha (the stable metabolite of PGI2) at different stages of the estrous cycle. Cumulative dose-response curves were obtained by a stepwise increase in the concentration of norepinephrine. The contraction of thoracic aortic rings induced by norepinephrine did not change significantly between estrus, metestrus and diestrus. However, aortic rings obtained on proestrus showed a significant reduction in the maximal contraction (Emax) induced by norepinephrine (p < 0.001). In addition, we found significant increases in vascular synthesis of PGE2 and PGI2 on proestrus (p < 0.001). These results indicate that vascular reactivity and vascular prostanoids synthesis are influenced by the hormonal changes occurring during the estrous cycle of normal female rats. It is possible that prostanoids generated locally may play an important role in the regulation of vasomotor tone in the systemic vascular bed throughout the estrous cycle.

Influence of the estrous cycle on the norepinephrine-induced contraction of rat aorta: relationship to vascular prostanoids biosynthesis

Since ovarian sex steroids (estradiol and progesterone) may affect both blood pressure and prostanoids synthesis, and because prostaglandin-E2 (PGE2) and prostacyclin (PGI2) can modulate the vascular action of pressor hormones, we investigated the vascular reactivity to norepinephrine during the estrous cycle of the rat. In addition, we determined the vascular biosynthesis of PGE2 and 6-keto-PGF1 alpha (the stable metabolite of PGI2) at different stages of the estrous cycle. Cumulative dose-response curves were obtained by a stepwise increase in the concentration of norepinephrine. The contraction of thoracic aortic rings induced by norepinephrine did not change significantly between estrus, metestrus and diestrus. However, aortic rings obtained on proestrus showed a significant reduction in the maximal contraction (Emax) induced by norepinephrine (p < 0.001). In addition, we found significant increases in vascular synthesis of PGE2 and PGI2 on proestrus (p < 0.001). These results indicate that vascular reactivity and vascular prostanoids synthesis are influenced by the hormonal changes occurring during the estrous cycle of normal female rats. It is possible that prostanoids generated locally may play an important role in the regulation of vasomotor tone in the systemic vascular bed throughout the estrous cycle