RESUMO
6-Nitrodopamine (6-ND) is an endogenous modulator of the contractility in the rat isolated epididymal vas deferens (RIEVD) and considered to be the main peripheral mediator of the emission process. Use of selective and unselective ß-adrenergic receptor antagonists has been associated with ejaculatory failure. Here, the effects of selective ß1- and ß1/ß2-adrenergic receptor antagonists on RIEVD contractions induced by 6-ND, dopamine, noradrenaline, adrenaline, and electric-field stimulation (EFS) were investigated. The selective ß1-adrenergic receptor antagonists atenolol (0.1 and 1 µï»¿M), betaxolol (1 µï»¿M), and metoprolol (1 µï»¿M) and the unselective ß1/ß2-adrenergic receptor antagonists propranolol (1 and 10 µï»¿M) and pindolol (10 µï»¿M) caused significant rightward shifts of the concentration-response curve to 6-ND (pA2 6.41, 6.91, 6.75, 6.47, and 5.74; for atenolol, betaxolol, metoprolol, propranolol, and pindolol), but had no effect on dopamine-, noradrenaline-, and adrenaline-induced contractions. The effects of selective ß1- and ß1/ß2-adrenergic receptor antagonists at a higher concentration (atenolol 1 µï»¿M, betaxolol 1 µï»¿M, metoprolol 1 µï»¿M, propranolol 10 µï»¿M, and pindolol 10 µï»¿M) also reduced the EFS-induced RIEVD contractions in control, but not in RIEVD obtained from L-NAME-treated animals. The selective ß1-adrenoceptor agonist RO-363, the selective ß2-adrenoceptor agonist salbutamol, and the selective ß3-adrenoceptor agonist mirabegron, up to 300 µï»¿M, had no effect on the RIEVD tone. The results demonstrate that ß1- and ß1-/ß2-adrenoceptor receptor antagonists act as 6-ND receptor antagonists in RIEVD, further confirming the main role of 6-ND in the RIEVD contractility.
Assuntos
Propranolol , Ducto Deferente , Antagonistas de Receptores Adrenérgicos beta 1/farmacologia , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Atenolol/farmacologia , Betaxolol/farmacologia , Dopamina/análogos & derivados , Epinefrina/farmacologia , Masculino , Metoprolol/farmacologia , Norepinefrina/farmacologia , Pindolol/farmacologia , Propranolol/farmacologia , RatosRESUMO
The cardiac circadian clock is responsible for the modulation of different myocardial processes, and its dysregulation has been linked to disease development. How this clock machinery is regulated in the heart remains an open question. Because noradrenaline (NE) can act as a zeitgeber in cardiomyocytes, we tested the hypothesis that adrenergic signaling resets cardiac clock gene expression in vivo. In its anti-phase with Clock and Bmal1, cardiac Per1 abundance increased during the dark phase, concurrent with the rise in heart rate and preceded by an increase in NE levels. Sympathetic denervation altered Bmal1 and Clock amplitude, while Per1 was affected in both amplitude and oscillatory pattern. We next treated mice with a ß-adrenergic receptor (ß-AR) blocker. Strikingly, the ß-AR blockade during the day suppressed the nocturnal increase in Per1 mRNA, without altering Clock or Bmal1. In contrast, activating ß-AR with isoproterenol (ISO) promoted an increase in Per1 expression, demonstrating its responsiveness to adrenergic input. Inhibitors of ERK1/2 and CREB attenuated ISO-induced Per1 expression. Upstream of ERK1/2, PI3Kγ mediated ISO induction of Per1 transcription, while activation of ß2-AR, but not ß1-AR induced increases in ERK1/2 phosphorylation and Per1 expression. Consistent with the ß2-induction of Per1 mRNA, ISO failed to activate ERK1/2 and elevate Per1 in the heart of ß2-AR-/- mice, whereas a ß2-AR antagonist attenuated the nocturnal rise in Per1 expression. Our study established a link between NE/ß2-AR signaling and Per1 oscillation via the PI3Ky-ERK1/2-CREB pathway, providing a new framework for understanding the physiological mechanism involved in resetting cardiac clock genes.
Assuntos
Regulação da Expressão Gênica , Sistema de Sinalização das MAP Quinases , Miocárdio/metabolismo , Proteínas Circadianas Period/biossíntese , Receptores Adrenérgicos beta 2/metabolismo , Fatores de Transcrição ARNTL/biossíntese , Fatores de Transcrição ARNTL/genética , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Proteínas CLOCK/biossíntese , Isoproterenol/farmacologia , Masculino , Camundongos , Camundongos Knockout , Proteínas Circadianas Period/genética , Receptores Adrenérgicos beta 2/genéticaRESUMO
The stress response is adaptive and aims to guarantee survival. However, the persistence of a stressor can culminate in pathology. Catecholamines released as part of the stress response over activate beta adrenoceptors (ß-AR) in the heart. Whether and how stress affects the expression of components of the intracellular environment in the heart is still, however, unknown. This paper used microarray to analyze the gene expression in the left ventricle wall of rats submitted to foot shock stress, treated or not treated with the selective ß2-AR antagonist ICI118,551 (ICI), compared to those of non-stressed rats also treated or not with ICI, respectively. The main findings were that stress induces changes in gene expression in the heart and that ß2-AR plays a role in this process. The vast majority of genes disregulated by stress were exclusive for only one of the comparisons, indicating that, in the same stressful situation, the profile of gene expression in the heart is substantially different when the ß2-AR is active or when it is blocked. Stress induced alterations in the expression of such a large number of genes seems to be part of stress-induced adaptive mechanism.
Assuntos
Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Regulação para Baixo/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Miocárdio/metabolismo , Estresse Fisiológico , Regulação para Cima/efeitos dos fármacos , Animais , Corticosterona/sangue , Ventrículos do Coração/efeitos dos fármacos , Sistema Imunitário/metabolismo , Masculino , Ratos , Ratos Wistar , Receptores Adrenérgicos beta 1/genética , Receptores Adrenérgicos beta 1/metabolismo , Receptores Adrenérgicos beta 2/química , Receptores Adrenérgicos beta 2/genética , Receptores Adrenérgicos beta 2/metabolismo , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismoRESUMO
The aim of this study was to determine whether monocyte/macrophage ß2-AR could act as the therapeutic target of antisympathetic excitation-induced atherosclerotic progression. Cultivated human THP-1 cells were divided into different groups and incubated with isoprenaline, metoprolol, propranolol or ß2-AR blocker for 24 h, together with oxidized low-density lipoprotein (ox-LDL). Afterwards, each group was analyzed for C-C chemokine receptor type 2 (CCR2) expression, monocyte chemotactic protein 1 (MCP-1) release into medium and cell migration ability. In the isoprenaline group, CCR2 protein level was increased, as well as the secretion of MCP-1, and cell motility was enhanced, in a concentration-dependent manner. Propranolol and ICI 118,551 significantly reversed the stimulatory effect of isoprenaline on THP-1 cells induced by ox-LDL, but only high concentrations of metoprolol interfered significantly with the action of isoprenaline (P < 0.05). Isoprenaline or a ß-AR blocker could mediate through ß2-AR, affecting MCP-1 secretion, CCR2 protein expression and cell migration capacity of THP-1 cells. Therefore, monocyte-macrophage ß2-AR may act as a target of antisympathetic excitation-induced atherosclerotic progression.
Assuntos
Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Aterosclerose/etiologia , Aterosclerose/metabolismo , Macrófagos/metabolismo , Monócitos/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Simpatolíticos/farmacologia , Antagonistas de Receptores Adrenérgicos beta 1/farmacologia , Aterosclerose/patologia , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Quimiocina CCL2/metabolismo , Progressão da Doença , Humanos , Receptores CCR2/metabolismoRESUMO
OBJECTIVES: Our main objectives were to investigate the affinity properties of endothelial and muscular α1D -adrenoceptors and to characterize the cross-talk between endothelial α1D -adrenoceptors and ß2 -adrenoceptors in rat carotid. METHODS: Relaxation and contraction concentration-response curves for phenylephrine (α1 -adrenergic agonist) were obtained in carotid rings in absence or presence of increasing concentrations of BMY7378 (α1D -adrenergic antagonist), combined or not with increasing concentration of ICI-118,551 (ß2 -adrenergic antagonist). Schild analysis was used to estimate the affinity constant from pA2 values of BMY7378. KEY FINDINGS: BMY7378 produced an unsurmountable antagonism on phenylephrine-induced relaxation but a surmountable antagonism on phenylephrine-induced contraction. BMY7378 potency was higher in inhibiting the relaxation than the contraction induced by phenylephrine because the rightward shifts induced by BMY7378 were greater in the relaxation. The apparent pA2 value for BMY7378 in phenylephrine-induced relaxation was greater than in contraction. When combined with ICI-118,551, BMY7378 yielded a surmountable antagonism on phenylephrine-induced relaxation and presented a pA2 value similar to that obtained in phenylephrine-induced contraction. CONCLUSIONS: Endothelial α1D -adrenoceptors, which mediates rat carotid relaxation, present high ligand affinity because of the cross-talk with ß2 -adrenoceptors, which explains the higher potency of phenylephrine in inducing relaxation than contraction and the atypical unsurmountable antagonism produced by BMY7378 on phenylephrine-induced relaxation.
Assuntos
Agonistas de Receptores Adrenérgicos alfa 1/farmacologia , Artérias Carótidas/efeitos dos fármacos , Receptor Cross-Talk , Receptores Adrenérgicos alfa 1/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Vasoconstrição/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Ligantes , Masculino , Fenilefrina/farmacologia , Ratos , Ratos WistarRESUMO
BACKGROUND: Temporomandibular joint (TMJ) receives rich sympathetic innervations that may contribute to TMJ pain through the local release of sympathomimetic amines. The aim of this study was to determine whether blockade of ß-adrenoceptors in the TMJ of male and female rats reduces formalin-induced TMJ nociceptive behaviour. METHODS: We co-administrated each one of the selective ß(1) -, ß(2) - and ß(3) -adrenoceptors antagonists, atenolol, ICI 118.551 and SR59230A, respectively, with formalin in the TMJ of male and proestrus and dioestrus female rats. Because intra-temporomandibular joint formalin induces significantly different concentration-dependent responses among the three groups, with dioestrus females showing greater responses than males or proestrus females, equi-nociceptive formalin concentrations were used to test the effects of the ß-adrenoceptor antagonists. RESULTS: We found that atenolol, ICI 118.551 and SR59230A significantly reduced formalin-induced TMJ nociception in a dose response fashion in both males and females. However, a lower dose of each ß-adrenoceptor antagonist was sufficient to significantly reduce nociceptive responses in females than in males. Administration of the highest doses of each ß-adrenoceptor antagonist in the TMJ contralateral to that receiving formalin did not affect formalin-induced nociception in males and females, confirming the local action of the ß-adrenoceptor antagonists. CONCLUSIONS: We conclude that blockade of ß-adrenoceptors in the temporomandibular joint suppresses formalin-induced TMJ nociceptive behaviour in both males and females but females are more responsive. These findings suggest that the use of ß-blockers in the treatment of TMJ pain might be of benefit, especially in females.
Assuntos
Antagonistas de Receptores Adrenérgicos beta 1/farmacologia , Antagonistas de Receptores Adrenérgicos beta 2/farmacologia , Antagonistas de Receptores Adrenérgicos beta 3/farmacologia , Atenolol/farmacologia , Nociceptividade/efeitos dos fármacos , Propanolaminas/farmacologia , Articulação Temporomandibular , Animais , Feminino , Injeções Intra-Articulares , Masculino , Medição da Dor/efeitos dos fármacos , Ratos , Ratos Wistar , Fatores SexuaisRESUMO
In the present work, we sought to mimic the internal state changes in response to a predator threat by pharmacologically stimulating the brain circuit involved in mediating predator fear responses, and explored whether this stimulation would be a valuable unconditioned stimulus (US) in an olfactory fear conditioning paradigm (OFC). The dorsal premammillary nucleus (PMd) is a key brain structure in the neural processing of anti-predatory defensive behavior and has also been shown to mediate the acquisition and expression of anti-predatory contextual conditioning fear responses. Rats were conditioned by pairing the US, which was an intra-PMd microinjection of isoproterenol (ISO; ß-adrenoceptor agonist), with amyl acetate odor-the conditioned stimulus (CS). ISO (10 and 40 nmol) induced the acquisition of the OFC and the second-order association by activation of ß-1 receptors in the PMd. Furthermore, similar to what had been found for contextual conditioning to a predator threat, atenolol (ß-1 receptor antagonist) in the PMd also impaired the acquisition and expression of OFC promoted by ISO. Considering the strong glutamatergic projections from the PMd to the dorsal periaqueductal gray (dPAG), we tested how the glutamatergic blockade of the dPAG would interfere with the OFC induced by ISO. Accordingly, microinjections of NMDA receptor antagonist (AP5, 6 nmol) into the dPAG were able to block both the acquisition, and partially, the expression of the OFC. In conclusion, we have found that PMd ß-1 adrenergic stimulation is a good model to mimic predatory threat-induced internal state changes, and works as a US able to mobilize the same systems involved in the acquisition and expression of predator-related contextual conditioning.