Identification and characterization of a vasopressin isoreceptor in porcine seminal vesicles.

Abstract

Neurohypophysial hormones stimulate the motility of tunica albuginea, epididymis, and vas deferens acting through oxytocin (OT) and V1 vasopressin receptors. To test the hypothesis that these hormones are involved also in the regulation of seminal vesicle physiology, we studied binding of properties are distinct from the previously described V1 and V2 vasopressin receptors and indicate the presence of a new class of AVP receptors. Although this vasopressin isoreceptor shares some pharmacological characteristics with the V1 (pressor) isoreceptor, it has low affinity for the V1 antagonist d(CH2)5-Tyr(Me)AVP and is linked to the adenylate cyclase system. The extremely high density of AVP receptors in porcine seminal vesicles (2 pmol per mg of protein) is comparable to the density of V2 vasopressin receptors in porcine renal medulla, suggesting a physiological role for vasopressin in the seminal vesicle.Vasopressin receptors have been identified and characterized in several mammalian tissues: kidney (1), liver (2), vascular smooth muscle cells (3), brain (4), pituitary gland (5), and the interstitial cells of the rat testis (6). Mitchell et al. (7) postulated the presence of two vasopressin isoreceptors, distinguished on the basis of functional criteria. The V1 subtype of receptors regulates cellular calcium metabolism, whereas the V2 subtype is functionally coupled to adenylate cyclase (1). The recent development of potent and selective ligands for these two isoreceptors allowed the identification of V1 isoreceptors in blood vessels, liver, brain, and interstitial cells of the testis (2-4, 6), whereas the V2 isoreceptor has been localized in the renal medulla (1).Oxytocin (OT) receptors were described in the uterus (8), mammary gland (9), oviduct (10), and hippocampus (11). These receptors, in mammals, are not functionally coupled to adenylate cyclase (12); it has been suggested that the occupancy of OT binding sites is associated with an increase of intracellular calcium, apparently via specific inhibition of Ca2+,Mg2+-ATPase (13).We have recently identified and characterized OT and V1 vasopressin receptors in the tunica albuginea of the testis, epididymis, and vas deferens ofthe prepubertal pig (14). Both in vitro and in vivo studies suggest that these receptors are involved in the regulation of the motility of the male genital tract (15). Seminal vesicles have a fibromuscular stroma that appears to be a target for androgens and estrogens (16). To test the hypothesis that these glands are also a target tissue for neurohypophysial hormones, we studied the binding of labeled OT and arginine vasopressin (AVP) and the response of adenylate cyclase to these hormones in membranes prepared from porcine seminal vesicles. MATERIALS AND METHODS[3H]AVP Ci/mmol; 1 Ci = 37 GBq) and [3H]OT 8824The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Similarity of vasopressin receptors in seminal vesicles and renal medulla of pigs

“…These results are in excellent agreement with our previous findings (Maggi et al, 1986). Similar binding specificity was obtained in medullopapillary membranes (Fig.…”

“…In contrast, the renal cortex developed only non-specific binding (data not shown). The concentrations of AVP sites in seminal vesicles reported in the present study are 10-fold lower than those previously observed by us (Maggi et al, 1986 Dorsa et al, 1983). In the seminal vesicles AVP receptors were found in the epithelial cells facing the lumen of the glands.…”

“…In the seminal vesicles AVP receptors were found in the epithelial cells facing the lumen of the glands. These findings, together with evidence that AVP receptors are coupled to adenylate cyclase in the kidney (Butlen et al, 1978) and seminal vesicles (Maggi et al, 1986), further indicate the similarity if not identity of AVP receptors in these two tissues. We therefore revise our previous interpretation that the seminal vesicle vasopressin receptors is of a subtype different from VI or V2 receptors (Maggi et al, 1986).…”

“…We have identified and characterized a high concentration of AVP binding sites in the seminal vesicles of pigs (Maggi et al, 1986). These receptors are linked to adenylate cyclase and display pharmacological characteristics different from those previously described for VI AVP sites.…”

Expression of Functional Estrogen Receptors in Human Fetal Male External Genitalia

“…The homogenate was appropriately diluted, and 100 l containing 0.70 mg protein for androgen binding or 0.35 mg for estrogen binding were incubated overnight at 4 C in a final volume of 250 l in TEDGMo with increasing concentrations of [2,4,6,7,16, H]-estradiol (specific activity, 150 Ci/mmol), in the absence (0.015, 0.03, 0.06, 0.12 nmol/liter) or presence (0.12 nmol/liter) of increasing concentrations of nonradioactive 17␤-estradiol (10 Ϫ11 to 10 Ϫ5 mol/liter) for estrogen binding or with increasing concentrations of [ 3 H]R1881 (specific activity, 68 Ci/mmol) in the absence (0.125, 0.25, 0.5, 1 nmol/liter) or presence (1 nm) of increasing concentrations of nonradioactive R1881 (10 Ϫ10 to 10 Ϫ6 mol/liter) for androgen binding. Dilution of tracer was performed to optimally characterize the high-affinity portion of the displacement curves (26). To prevent R1881 binding to progesterone receptor (PR), 1 mol/liter triamcinolone acetonide was added to each tube.…”