Testosterone relaxes rabbit seminal vesicle by calcium channel inhibition

Bilateral orchiectomy deteriorates the structure and function of seminal vesicles in a rat model

The effects of hormone levels on ejaculation are known. In addition to thyroid hormone levels, testosterone levels are also associated with ejaculation, but no consensus has been reached on this issue. Thus, we investigated the effect of decreased testosterone levels due to bilateral orchiectomy on the chemical stimulation-induced ejaculation phases in rats. Twenty-one male Wistar rats were randomized into the orchiectomy, sham, and control groups, with seven rats in each group. Bilateral orchiectomy was performed. The ejaculation parameters were evaluated 5 days after the sham and bilateral orchiectomy operations and the waiting period in the control group. The seminal vesicle (SV) phasic contraction number and increase in basal pressure amplitude were significantly lower in the orchiectomy group (6.9 ± 3.3 and 0.6 ± 0.3 mmHg) than in the sham and control groups (11.2 ± 1.7 and 1.0 ± 0.4 mmHg, and 14.5 ± 6.6 and 1.1 ± 0.2 mmHg, respectively; p = 0.016 and p = 0.03, respectively). The interval between the SV contractions was significantly longer in the orchiectomy group (166.2 ± 104.3 s) than in the sham and control groups (76.0 ± 15.5 s and 63.1 ± 31.1 s, respectively; p = 0.014 (between groups), orchiectomy vs sham p = 0.040 and orchiectomy vs control p = 0.018). The SV weights of the rats were significantly lower in the orchiectomy group (0.14 ± 0.01 g) than in the sham and control groups (0.37 ± 0.05 g and 0.48 ± 0.03 g respectively; p < 0.0001 (between groups), orchiectomy vs sham p < 0.0001 and orchiectomy vs control p < 0.0001). The groups showed no significant differences in ejaculation time, SV basal pressure, SV maximum amplitude, and bulbospongiosus muscle contraction electromyographic activity. Our results partially clarified the relationship between decreased testosterone levels and ejaculation. Decreased testosterone levels caused statistically significant changes in SV functions and affected the ejaculation emission phase.

Dehydroepiandrosterone, its metabolites and ion channels

This review is focused on the physiological and pathophysiological relevance of steroids influencing the activities of the central and peripheral nervous systems with regard to their concentrations in body fluids and tissues in various stages of human life like the fetal development or pregnancy. The data summarized in this review shows that DHEA and its unconjugated and sulfated metabolites are physiologically and pathophysiologically relevant in modulating numerous ion channels and participate in vital functions of the human organism. DHEA and its unconjugated and sulfated metabolites including 5α/β-reduced androstane steroids participate in various physiological and pathophysiological processes like the management of GnRH cyclic release, regulation of glandular and neurotransmitter secretions, maintenance of glucose homeostasis on one hand and insulin insensitivity on the other hand, control of skeletal muscle and smooth muscle activities including vasoregulation, promotion of tolerance to ischemia and other neuroprotective effects. In respect of prevalence of steroid sulfates over unconjugated steroids in the periphery and the opposite situation in the CNS, the sulfated androgens and androgen metabolites reach relevance in peripheral organs. The unconjugated androgens and estrogens are relevant in periphery and so much the more in the CNS due to higher concentrations of most unconjugated steroids in the CNS tissues than in circulation and peripheral organs. This article is part of a Special Issue entitled "Essential role of DHEA".

The Relaxing Effect of α-Defensin 1 on the Adrenergic Responses of Rat Bladder

Defensins, cysteine-rich cationic polypeptides released from neutrophils, are known to have powerful antimicrobial properties. In this study, we sacrificed 30 rats to investigate the effects of α-defensin 1 on detrusor muscle contractions in isolated rat bladder. From the experiments we found relaxing effects of α-defensin 1 on the contractions induced by phenylephrine (PE) but not by bethanechol (BCh) in the detrusor smooth muscles. To determine the mechanisms of the effects of α-defensin 1, the changes of effects on PE-induced contraction by α-defensin 1 pretreatment were observed after pretreatment of Rho kinase inhibitor (Y-27632), protein kinase C (PKC) inhibitor (Calphostin C), potent activator of PKC (PDBu; phorbol 12,13-dibutyrate), and NF-κB inhibitors (PDTC; pyrrolidinedithiocarbamate and sulfasalazine). The contractile responses of PE (10(-9)~10(-4) M) were significantly decreased in some concentrations of α-defensin 1 (5×10(-9) and 5×10(-8) M). When strips were pretreated with NF-κB inhibitors (PDTC and sulfasalazine; 10(-7)~10(-6) M), the relaxing responses by α-defensin 1 pretreatment were disappeared. The present study demonstrated that α-defensin 1 has relaxing effects on the contractions of rat detrusor muscles, through NF-κB pathway. Further studies in vivo are required to clarify whether α-defensin 1 might be clinically related with bladder dysfunction by inflammation process.

Pharmacological evidence that Ca²+ channels and, to a lesser extent, K+ channels mediate the relaxation of testosterone in the canine basilar artery

Testosterone induces vasorelaxation through non-genomic mechanisms in several isolated blood vessels, but no study has reported its effects on the canine basilar artery, an important artery implicated in cerebral vasospasm. Hence, this study has investigated the mechanisms involved in testosterone-induced relaxation of the canine basilar artery. For this purpose, the vasorelaxant effects of testosterone were evaluated in KCl- and/or PGF(₂α)-precontracted arterial rings in vitro in the absence or presence of several antagonists/inhibitors/blockers; the effect of testosterone on the contractile responses to CaCl₂ was also determined. Testosterone (10-180 μM) produced concentration-dependent relaxations of KCl- or PGF(₂α)-precontracted arterial rings which were: (i) unaffected by flutamide (10 μM), DL-aminoglutethimide (10 μM), actinomycin D (10 μM), cycloheximide (10 μM), SQ 22,536 (100 μM) or ODQ (30 μM); and (ii) significantly attenuated by the blockers 4-aminopyridine (K(V); 1 mM), BaCl₂ (K(IR); 30 μM), iberiotoxin (BK(Ca²+); 20 nM), but not by glybenclamide (K(ATP); 10 μM). In addition, testosterone (31, 56 and 180 μM) and nifedipine (0.01-1 μM) produced a concentration-dependent blockade of the contraction to CaCl₂ (10 μM to 10 mM) in arterial rings depolarized by 60mM KCl. These results, taken together, show that testosterone relaxes the canine basilar artery mainly by blockade of voltage-dependent Ca²+ channels and, to a lesser extent, by activation of K+ channels (K(IR), K(V) and BK(Ca²+)). This effect does not involve genomic mechanisms, production of cAMP/cGMP or the conversion of testosterone to 17β-estradiol.

Spontaneous contractions augmented by cholinergic and adrenergic systems in the human ureter

Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3~4 times within 5 minutes in the longitudinal group. ACh (10(-4) M) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of 10(-5) M glibenclamide. Receptor tyrosine kinase (c-kit) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.