Enhancement of trypsin-induced contraction by in vivo treatment with 17beta-estradiol and progesterone in rat myometrium

Adverse effects of 4-tert-octylphenol on the production of oxytocin and hCG in pregnant rats

Endocrine-disrupting chemicals (EDCs) are exogenous substances that alter the structure or function of the endocrine system. 4-Tert-octylphenol (OP) is one of the most representative EDCs and has estrogenic effects. In this study, we examined the effects of ethinyl estradiol (EE) and OP on the pituitary gland, placenta, and uterus of pregnant rats. Expression levels of human chorionic gonadotropin (hCG), oxytocin (OT), and contraction-associated proteins (CAPs) were determined, and uterine contractile activity was measured by uterine contraction assay. EE and OP both increased mRNA expression of OT and hCG in the pituitary gland but not the placenta. Since OT and hCG control uterine contraction, we next examined CAP expression in the uterus. Expression of 15-hydroxyprostaglandin-dehydrogenase (PGDH) was upregulated by OP, whereas expression of other CAPs was unaffected. To clarify the effect of OP on uterine contraction in pregnant rats, uterine contraction assay was performed. The 17β-Estradiol (E2) did not affect contraction of primary uterine cells harvested from pregnant rats in a 3D collagen gel model. However, OP showed different effects from E2 by significantly reducing contraction activity. In summary, we demonstrated that OP interferes with regulation of OT and hCG in the pituitary gland as well as PGDH in the uterus, thereby reducing uterine contraction activity. This result differs from the action of endogenous E2. Collectively, these findings suggest that exposure to EDCs such as OP during pregnancycan reduce uterine contractile ability, which may result in contraction-associated adverse effects such as metratonia, bradytocia, and uterine leiomyomata.

Effects of estrogen and estrogenic compounds, 4-tert-octylphenol, and bisphenol A on the uterine contraction and contraction-associated proteins in rats

We examined the effects of estradiol (E2), 4-tert-octylphenol (OP), and bisphenol A (BPA) on uterine contractions in immature rats. The expression and localization of contraction-associated proteins (CAPs), and contractility of rat uterus with a collagen gel contraction assay were analyzed. E2, OP, and BPA all increased oxytocin (OT)-related pathway, while the prostaglandin-related signaling was reduced. Interestingly, E2 and estrogenic compounds showed distinct effects on the contractile activity of uterine cells. E2 enhanced the contractility, while OP and BPA significantly decreased it. Immunohistochemical analysis of CAPs showed distinct regulation of prostaglandin F receptor localization by E2 and estrogenic compounds, which may explain the different contractile activities of those reagents. In summary, we demonstrate that E2, OP, and BPA regulate CAP expression in a similar manner in the immature rat uterus, however, the effects on contractile activity were modulated differently. These findings suggest that OP and BPA interfere with uterine contractility.

Proteinase-activated receptors in the lower urinary tract

Proteinase-activated receptors (PARs) are G-protein-coupled receptors that convert specific extracellular proteolytic activity into intracellular signals, and have been suggested to play diverse roles in the body. In this review, evidence for the roles of PARs in bladder contractility and inflammation are presented. The role of PARs in prostate cancer is also reviewed. The existing literature in this area can be difficult to interpret due to the many nonspecific actions of the pharmacological tools employed. Although there are reports that PAR activators can cause contraction of bladder smooth muscle, further pharmacological and molecular studies are required to define roles for these receptors in bladder contractility. While structural studies suggest that roles for PARs in bladder inflammation are likely, few functional investigations have been performed. The significance of the expression of PARs on sensory nerves innervating the bladder and changes in receptor expression in inflammatory disease models are fascinating areas for future research. Finally, it seems probable that PARs, particularly PAR1, may play important roles in the growth and metastasis of prostate cancers.

Plasmin induces endothelium-dependent nitric oxide-mediated relaxation in the porcine coronary artery

OBJECTIVE

Plasmin is a key enzyme in fibrinolysis. We attempted to determine the possible role of plasmin in the regulation of vascular tone, while also investigating the mechanism of plasmin-induced vasorelaxation.

METHODS AND RESULTS

In porcine coronary artery, plasmin induced an endothelium-dependent relaxation. This relaxing effect was mostly abolished by a proteinase inhibitor, a plasmin inhibitor, or a nitric oxide (NO) synthase inhibitor. The preceding stimulation with plasmin significantly inhibited the subsequent relaxation induced by thrombin but not that induced by proteinase-activated receptor-1-activating peptide. The relaxation induced by trypsin and substance P remained unaffected by the preceding plasmin stimulation. The pretreatment with plasmin, thrombin, or trypsin significantly attenuated the plasmin-induced relaxation. In porcine coronary artery endothelial cells (PCAECs) and human umbilical vein endothelial cells (HUVECs), plasmin induced a transient elevation in the cytosolic Ca2+ concentrations ([Ca2+]i). The preceding stimulation with plasmin inhibited the subsequent [Ca2+]i elevation induced by thrombin but not that induced by trypsin. In PCAECs, plasmin concentration-dependently induced NO production.

CONCLUSIONS

The present study demonstrated, for the first time, that plasmin induced an endothelium-dependent NO-mediated relaxation in the porcine coronary artery, while also showing plasmin to specifically inactivate the thrombin receptor.