The purpose of this study was to evaluate the effects of stress and estradiol (E2) on pain tolerance. Ovariectomized rats were assigned to treatment groups based on a 2 x 4 factorial design comprising stress (nonstress x stress) and hormone treatment vehicle x E2 [0.25 mg/kg/d]) x estrogen receptor alpha (ERalpha)-selective agonist propyl pyrazole triol (1 mg/kg/d) x estrogen receptor beta (ERb...

BACKGROUND The H3 histamine receptor is a Gi-coupled GPCR that has been proven to exist in different agonist-induced states, including that defined by the protean agonist proxyfan. Several GPCRs are now known to exist in different states. For some of these, antagonist affinity measurement remain constant regardless of the state of the receptor, for others e.g. the beta-adrenoceptors, the antago...

Two of the common mechanisms regulating G protein-coupled receptor (GPCR) signal transduction are phosphorylation and sequestration (internalization). Agonist-mediated receptor phosphorylation by the beta-adrenergic receptor kinase (betaARK) facilitates subsequent interaction with an arrestin protein, resulting in receptor desensitization. Studies of the beta2-adrenergic receptor (beta2AR) rece...

Two GPCRs (G-protein-coupled receptors), TRHR (thyrotropin-releasing hormone receptor) and beta(2)AR (beta(2)-adrenergic receptor), are regulated in distinct manners. Following agonist binding, TRHR undergoes rapid phosphorylation attributable to GRKs (GPCR kinases); beta(2)AR is phosphorylated by both second messenger-activated PKA (protein kinase A) and GRKs with slower kinetics. TRHR co-inte...

Spontaneous contractile force of muscle strips isolated from male rabbit urinary bladder dome (detrusor) and base (trigonal muscle) was significantly inhibited by isoproterenol (10(-7)-10(-5) M), a non-specific beta-adrenoceptor agonist or by terbutaline (10(-8)-10(-5) M), a selective beta 2-adrenoceptor agonist. The EC50 values for isoproterenol and terbutaline in detrusor were the same as tho...

BACKGROUND Aging decreases cardiac beta-adrenergic responsiveness in model systems and in humans in vivo. The purpose of this study was to comprehensively evaluate the age-related changes in the beta-receptor-G protein-adenylyl cyclase complex in nonfailing human hearts. METHODS AND RESULTS Twenty-six nonfailing explanted human hearts aged 1 to 71 years were obtained from organ donors and sub...

OBJECTIVES beta-Adrenergic receptor kinase (beta ARK) phosphorylates and thereby inactivates agonist-occupied beta-adrenergic receptors (beta AR). beta ARK is thought to play an important role in the regulation of cardiac function. Therefore, we studied beta ARK activation and its inhibition in intact smooth muscle cells and in cardiomyoblasts. METHODS AND RESULTS beta AR agonist-stimulated t...

background and purpose: the clinical outcome of intrauterine insemination (iui) treatment cycles employing a gonadotrophin-releasing hormone agonist [superfact)] or human chorionic gonadotrophin (hcg) for ovulation induction was compared. materials and methods: a group of 100 patients presenting with amenorrhoea, oligomenorrhoea or unexplained infertility were all treated with clomiphene 100 mg...

BACKGROUND Salbutamol exhibits partial agonist/antagonist activity at airway beta 2 receptors in vitro in that it attenuates the bronchorelaxant effect of the full agonist isoprenaline. The aim of the present study was to characterise the partial beta 2 agonist/antagonist activity of salbutamol in vivo during supine rest and exercise, in states of low and high adrenergic tone. METHODS Eight n...