RESUMEN
Previous reports showed that 17beta-estradiol implants attenuate in vivo coronary hyperreactivity (CH), characterized by long-duration vasoconstrictions (in coronary angiographic experiments), in menopausal rhesus monkeys. Prolonged Ca2+ contraction signals that correspond with CH in coronary vascular muscle cells (VMC) to the same dual-constrictor stimulus, serotonin + the thromboxane analog U-46619, in estrogen-deprived VMC were suppressed by >72 h in 17beta-estradiol. The purpose of this study was to test whether an endogenous estrogen metabolite with estrogen receptor-beta (ER-beta) binding activity, estriol (E3), suppresses in vivo and in vitro CH. E3 treatment in vivo for 4 wk significantly attenuated the angiographically evaluated vasoconstrictor response to intracoronary serotonin + U-46619 challenge. In vitro treatment of rhesus coronary VMC for >72 h with nanomolar E3 attenuated late Ca2+ signals. This reduction of late Ca2+ signals also appeared after >72 h of treatment with subnanomolar 5alpha-androstane-3beta,17beta-diol (3beta-Adiol), an endogenous dihydrotestosterone metabolite with ER-beta binding activity. R,R-tetrahydrochrysene, a selective ER-beta antagonist, significantly blocked the E3- and 3beta-Adiol-mediated attenuation of late Ca2+ signal increases. ER-beta and thromboxane-prostanoid receptor (TPR) were coexpressed in coronary arteries and aorta. In vivo E3 treatment attenuated aortic TPR expression. Furthermore, in vitro treatment with E3 or 3beta-Adiol downregulated TPR expression in VMC, which was blocked for both agonists by pretreatment with R,R-tetrahydrochrysene. E3- and 3beta-Adiol-mediated reduction in persistent Ca2+ signals is associated with ER-beta-mediated attenuation of TPR expression and may partly explain estrogen benefits in coronary vascular muscle.
Asunto(s)
Vasoespasmo Coronario/tratamiento farmacológico , Estriol/uso terapéutico , Receptor beta de Estrógeno/metabolismo , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacología , Administración Cutánea , Androstano-3,17-diol/farmacología , Animales , Señalización del Calcio/efectos de los fármacos , Crisenos/farmacología , Vasoespasmo Coronario/inducido químicamente , Estriol/administración & dosificación , Estriol/farmacología , Receptor beta de Estrógeno/agonistas , Receptor beta de Estrógeno/antagonistas & inhibidores , Femenino , Expresión Génica/efectos de los fármacos , Genisteína/farmacología , Macaca mulatta , Músculo Liso Vascular/citología , Músculo Liso Vascular/efectos de los fármacos , Nitrilos/farmacología , Propionatos/farmacología , Receptores de Tromboxanos/biosíntesis , Serotonina/farmacología , Vasoconstricción/efectos de los fármacosRESUMEN
TRPV1, the capsaicin receptor, is expressed not only in nociceptive neurons, but also in other locations, including the hypothalamus. Studies involving systemic or intrahypothalamic capsaicin administration have suggested a role for TRPV1 in body temperature control. To explore this possibility, we examined thermoregulatory responses in TRPV1-/- mice. These mutant animals exhibited no obvious changes in circadian body temperature fluctuation, tolerance to increased (35 degrees C) or decreased (4 degrees C) ambient temperature or ethanol-induced hypothermia. In contrast, fever production in response to the bacterial pyrogen, lipopolysaccharide (LPS) was significantly attenuated in TRPV1-/- mice. Despite this finding, we detected no significant differences between TRPV1-/- and control mice in the extent of LPS-induced c-Fos expression in numerous fever-related brain subregions. These results suggest that TRPV1 participates in the generation of polyphasic fever, perhaps at sites outside the brain.
Asunto(s)
Regulación de la Temperatura Corporal/genética , Fiebre/genética , Canales Iónicos/deficiencia , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Ritmo Circadiano/efectos de los fármacos , Ritmo Circadiano/fisiología , Frío , Fiebre/inducido químicamente , Calor , Lipopolisacáridos/farmacología , Masculino , Ratones , Ratones Mutantes , Proteínas Proto-Oncogénicas c-fos/biosíntesis , Pirógenos/farmacología , Canales Catiónicos TRPVRESUMEN
Recent electrophysiological studies of cultured dorsal root and trigeminal ganglion neurons have suggested that multiple ionic mechanisms underlie the peripheral detection of cold temperatures. Several candidate "cold receptors," all of them ion channel proteins, have been implicated in this process. One of the most promising candidates is TRPM8, a nonselective cationic channel expressed in a subpopulation of sensory neurons that is activated both by decreases in temperature and the cooling compound menthol. However, evidence for the expression of TRPM8 in functionally defined cold-sensitive neurons has been lacking. Here, we combine fluorometric calcium imaging of cultured rat trigeminal neurons with single-cell RT-PCR to demonstrate that there are distinct subpopulations of cold responsive neurons and that TRPM8 likely contributes to cold transduction in one of them. TRPM8 is preferentially expressed within a subset of rapidly responsive, low-threshold (approximately 30 degrees C), cold-sensitive neurons. A distinct class of slowly responsive cold-sensitive neurons that is activated at lower temperatures (approximately 20 degrees C) generally lacks detectable TRPM8 mRNA. Together with previous findings, our data support the notion that cold responsive neurons are functionally heterogeneous.
Asunto(s)
Frío , Canales Iónicos/análisis , Proteínas de Neoplasias/análisis , ARN Mensajero/análisis , Ganglio del Trigémino/química , Animales , Regulación de la Temperatura Corporal , Calcio/fisiología , Señalización del Calcio , Técnicas de Cultivo de Célula , Cartilla de ADN , Fluorometría , Canales Iónicos/genética , Canales Iónicos/fisiología , Masculino , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/fisiología , Ratas , Ratas Sprague-Dawley , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Canales Catiónicos TRPM , Termorreceptores/fisiología , Ganglio del Trigémino/fisiologíaRESUMEN
We have investigated the intracellular signaling mechanisms underlying the release of nitric oxide (NO) evoked by beta-adrenoceptor (AR) agonists in urinary bladder strips and cultured bladder urothelial cells from adult rats. Reverse transcription-PCR revealed that inducible NO synthase and endothelial NOS but not neuronal NOS genes were expressed in urothelial cells. NO release from both urothelial cells and bladder strips was decreased (37-42%) in the absence of extracellular Ca2+ (100 microm EGTA) and was ablated after incubation with BAPTA-AM (5 microm) or caffeine (10 mm), indicating that the NO production is mediated in part by intracellular calcium stores. NO release was reduced (18-24%) by nifedipine (10 microm) and potentiated (29-32%) by incubation with the Ca2+ channel opener BAYK8644 (1-10 microm). In addition, beta-AR-evoked NO release (isoproterenol; dobutamine; terbutaline; 10(-9) to 10(-5) m) was blocked by the NOS inhibitors N(G)-nitro-L-arginine methyl ester (30 microm) or N(G)-monomethyl-L-arginine (50 microm), by beta-adrenoceptor antagonists (propranol, beta1/beta2; atenolol, beta1; ICI 118551; beta2; 100 microm), or by the calmodulin antagonist trifluoperazine (50 microm). Incubating cells with the nonhydrolyzable GTP analog GTPgammaS (1 microm) or the membrane-permeant cAMP analog dibutyryl-cAMP (10-100 microm) directly evoked NO release. Forskolin (10 microm) or the phosphodiesterase IBMX (50 microm) enhanced (39-42%) agonist-evoked NO release. These results indicate that beta-adrenoceptor stimulation activates the adenylate cyclase pathway in bladder epithelial cells and initiates an increase in intracellular Ca2+ that triggers NO production and release. These findings are considered in light of recent reports that urothelial cells may exhibit a number of "neuron-like" properties, including the expression of receptors/ion channels similar to those found in sensory neurons.