RESUMO
Pineal gland secretes the hormone melatonin at night with a circadian rhythm. The synthesis and secretion of melatonin are stimulated at night by norepinephrine released by sympathetic postganglionic neurons projecting from the superior cervical ganglia. Norepinephrine simultaneously activates α- and ß-adrenoceptors, triggering melatonin synthesis.To study the regulation of melatonin production and secretion, it is very convenient to use an ex vivo preparation. Thus, it is possible to keep intact pineal glands in culture and to study the actions of agonists, antagonists, modulators, toxic agents, etc., in melatonin synthesis. Artificial melatonin synthesis stimulation in vitro is usually achieved by using a ß-adrenergic agonist alone or in association with an α-adrenergic agonist. In this chapter, the methodology of cultured pineal glands will be described. Several papers were published by our group using this methodology, approaching the role played in melatonin synthesis control by angiotensin II and IV, insulin, glutamate, voltage-gated calcium channels, anhydroecgonine methyl ester (AEME, crack-cocaine product), monosodium glutamate (MSG), signaling pathways like NFkB, pathophysiological conditions like diabetes, etc.
Assuntos
Cocaína , Insulinas , Melatonina , Glândula Pineal , Agonistas alfa-Adrenérgicos/metabolismo , Agonistas alfa-Adrenérgicos/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Angiotensina II/metabolismo , Canais de Cálcio/metabolismo , Ritmo Circadiano/fisiologia , Melatonina/metabolismo , Norepinefrina , Glândula Pineal/metabolismo , Receptores Adrenérgicos beta/metabolismo , Glutamato de SódioRESUMO
Upon retrieval, an aversive memory can undergo destabilization and reconsolidation. A traumatic-like memory, however, may be resistant to this process. The present study sought to contribute with a strategy to overcome this potential issue by investigating whether generalized fear retrieval is susceptible to destabilization-reconsolidation that can be pharmacologically modified. We hypothesized that exposure to a context that elicits moderate generalization levels would allow a malleable memory state. We developed a fear conditioning protocol in context A (cxt-A) paired with yohimbine administration to promote significant fear to a non-conditioned context B (cxt-B) in rats, mimicking the enhanced noradrenergic activity reported after traumatic events in humans. Next, we attempted to impair the reconsolidation phase by administering clonidine (CLO) immediately after exposure to cxt-A, cxt-B, or a third context C (cxt-C) neither conditioned nor generalized. CLO administered post-cxt-B exposure for two consecutive days subsequently resulted in decreased freezing levels in cxt-A. CLO after cxt-B only once, after cxt-A or cxt-C in two consecutive days, or independently of cxt-B exposures did not affect fear in a later test. A 6-h-delay in CLO treatment post-cxt-B exposures produced no effects, and nimodipine administered pre-cxt-B exposures precluded the CLO action. We then quantified the Egr1/Zif268 protein expression following cxt-B exposures and CLO treatments. We found that these factors interact to modulate this memory destabilization-reconsolidation mechanism in the basolateral amygdala but not the dorsal CA1 hippocampus. Altogether, memory destabilization can accompany generalized fear expression; thus, we may exploit it to potentiate reconsolidation blockers' action.
Assuntos
Medo/psicologia , Generalização Psicológica , Consolidação da Memória/fisiologia , Memória/fisiologia , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Região CA1 Hipocampal/efeitos dos fármacos , Clonidina/farmacologia , Proteína 1 de Resposta de Crescimento Precoce/biossíntese , Proteína 1 de Resposta de Crescimento Precoce/genética , Extinção Psicológica , Masculino , Transtornos da Memória/induzido quimicamente , Transtornos da Memória/psicologia , Rememoração Mental , Ratos , Ratos Wistar , Simpatolíticos , IoimbinaRESUMO
Somatosensory afferent transmission strength is controlled by several presynaptic mechanisms that reduce transmitter release at the spinal cord level. We focused this investigation on the role of α-adrenoceptors in modulating sensory transmission in low-threshold myelinated afferents and in pathways mediating primary afferent depolarization (PAD) of neonatal mouse spinal cord. We hypothesized that the activation of α-adrenoceptors depresses low threshold-evoked synaptic transmission and inhibits pathways mediating PAD. Extracellular field potentials (EFPs) recorded in the deep dorsal horn assessed adrenergic modulation of population monosynaptic transmission, while dorsal root potentials (DRPs) recorded at root entry zone assessed adrenergic modulation of PAD. We found that noradrenaline (NA) and the α1-adrenoceptor agonists phenylephrine and cirazoline depressed synaptic transmission (by 15, 14 and 22%, respectively). DRPs were also depressed by NA, phenylephrine and cirazoline (by 62, 30, and 64%, respectively), and by the α2-adrenoceptor agonist clonidine, although to a lower extent (20%). We conclude that NA depresses monosynaptic transmission of myelinated afferents onto deep dorsal horn neurons via α1-adrenoceptors and inhibits interneuronal pathways mediating PAD through the activation of α1- and α2-adrenoceptors. The functional significance of these modulatory actions in shaping cutaneous and muscle sensory information during motor behaviors requires further study.
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Fenômenos Eletrofisiológicos/fisiologia , Fibras Nervosas Mielinizadas/fisiologia , Neurônios Aferentes/fisiologia , Receptores Adrenérgicos alfa 1/fisiologia , Receptores Adrenérgicos alfa 2/fisiologia , Corno Dorsal da Medula Espinal/fisiologia , Transmissão Sináptica/fisiologia , Animais , Animais Recém-Nascidos , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos BALB C , Vias Neurais/fisiologia , Receptores Adrenérgicos alfa 1/efeitos dos fármacos , Receptores Adrenérgicos alfa 2/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacosRESUMO
Neryl butyrate is a constituent of volatile oils obtained from aromatic plants. Aliphatic organic compound analogues chemically close to neryl butyrate possess vasodilator properties in rat aorta. To evaluate whether neryl butyrate has relaxing properties, this study tested its effects on isolated rat aorta. Unlike the analogues, neryl butyrate did not show relaxant profile in aortic rings precontracted with phenylephrine, but induced a contraction when it stimulated aortic rings under resting tonus. The contractile effect augmented in endothelium-denuded aortic rings. Treatment of endothelium-intact preparations with the nitric oxide synthase inhibitor L-NAME or the guanylyl cyclase inhibitor ODQ also augmented the contractile effect of neryl butyrate. Such phenomenon was absent in the presence of the cyclooxygenase inhibitor indomethacin. Contractile responses decreased in the presence of verapamil, a L-type Ca2+ channel blocker, or when Ca2+ was removed from the extracellular solution. Antagonists of α-adrenergic receptors (prazosin and yohimbine), but not the thromboxane-prostanoid receptor seratrodast, reversed the contraction induced by neryl butyrate. The α1A selective antagonist RS-17053 antagonized the neryl butyrate-induced contraction. The contraction caused by neryl butyrate was decreased by inhibiting the phospholipase C or the rho-associated kinase with U-73122 or Y-27632, respectively. Injected intravenously to awake rats, neryl butyrate induced arterial hypotension and bradycardia. Decreased frequency was also present in isolated right atrium preparations. In conclusion, the contractile effects of neryl butyrate were inhibited by α-adrenergic antagonists, indicating the involvement of α-adrenoceptors in the mechanism of action. In vivo, neryl butyrate caused hypotension, suggesting that other systemic influence than vasoconstriction may occur.
Assuntos
Aorta Torácica/efeitos dos fármacos , Butiratos/farmacologia , Vasoconstrição/efeitos dos fármacos , Vasoconstritores/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Amidas/farmacologia , Animais , Aorta Torácica/fisiologia , Cálcio/farmacologia , Estrenos/farmacologia , Átrios do Coração/efeitos dos fármacos , Técnicas In Vitro , Masculino , Fenilefrina/farmacologia , Inibidores de Fosfodiesterase/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Pirrolidinonas/farmacologia , Ratos WistarRESUMO
To study whether hypercaloric diet-induced obesity deteriorates vascular contractility of rat aorta through functional changes in α1 adrenergic and/or AT1 Angiotensin II receptors. Angiotensin II- or phenylephrine-induced contraction was tested on isolated aorta rings with and without endothelium from female Wistar rats fed for 7 weeks with hypercaloric diet or standard diet. Vascular expression of Angiotensin II Receptor type 1 (AT1R), Angiotensin II Receptor type 2 (AT2R), Cyclooxygenase-1 (COX-1), Cyclooxygenase-2 (COX-2), inducible Nitric Oxide Synthase (iNOS) and endothelial Nitric Oxide Synthase (eNOS), as well as blood pressure, glucose, insulin and angiotensin II blood levels were measured. Diet-induced obesity did not significantly change agonist-induced contractions (Emax and pD2 hypercaloric diet vs standard diet n.s.d.) of both intact (e+) or endothelium free (e-) vessels but significantly decrease both phenylephrine and angiotensin II contraction (Emax p < 0.01 hypercaloric diet vs standard diet) in the presence of both prazosin and losartan but only in endothelium-intact vessels. Diet-induced obesity did not change angiotensin II AT1, AT2 receptor proteins expression but reduced COX-1 and NOS2 ( p < 0.05 vs standard diet). Seven-week hypercaloric diet-induced obesity produces alterations in vascular adrenergic and angiotensin II receptor dynamics that suggest an endothelium-dependent adrenergic/angiotensin II crosstalk. These changes reflect early-stage vascular responses to obesity.
Assuntos
Aorta/metabolismo , Dieta/efeitos adversos , Endotélio Vascular/metabolismo , Obesidade/metabolismo , Receptor Tipo 1 de Angiotensina/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Vasoconstrição , Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Animais , Aorta/efeitos dos fármacos , Aorta/fisiopatologia , Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiopatologia , Ingestão de Energia , Feminino , Técnicas In Vitro , Proteínas de Membrana/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Obesidade/etiologia , Obesidade/fisiopatologia , Ratos Wistar , Receptor Tipo 1 de Angiotensina/efeitos dos fármacos , Receptor Tipo 2 de Angiotensina/metabolismo , Receptores Adrenérgicos alfa 1/efeitos dos fármacos , Transdução de Sinais , Fatores de Tempo , Vasoconstrição/efeitos dos fármacosRESUMO
Human α1D-adrenoceptors are G protein-coupled receptors that mediate adrenaline/noradrenaline actions. There is a growing interest in identifying regulatory domains in these receptors and determining how they function. In this work, we show that the absence of the human α1D-adrenoceptor carboxyl tail results in altered ERK (extracellular signal-regulated kinase) and p38 phosphorylation states. Amino terminus-truncated and both amino and carboxyl termini-truncated α1D-adrenoceptors were transfected into Rat-1, HEK293, and B103 cells, and changes in the phosphorylation state of extracellular signal-regulated kinase was assessed using biochemical and biophysical approaches. The phosphorylation state of other protein kinases (p38, MEK1, and Raf-1) was also studied. Noradrenaline-induced ERK phosphorylation in Rat-1 fibroblasts expressing amino termini-truncated α1D-adrenoceptors. However, in cells expressing receptors with both amino and carboxyl termini truncations, noradrenaline-induced activation was abrogated. Interestingly, ERK phosphorylation that normally occurs through activation of endogenous G protein-coupled receptors, EGF receptors, and protein kinase C, was also decreased, suggesting that downstream steps in the mitogen-activated protein kinase pathway were affected. A similar effect was observed in B103 cells but not in HEK 293 cells. Phosphorylation of Raf-1 and MEK1 was also diminished in Rat-1 fibroblasts expressing amino- and carboxyl-truncated α1D-adrenoceptors. Our data indicate that expression of carboxyl terminus-truncated α1D-adrenoceptors alters ERK and p38 phosphorylation state.
Assuntos
MAP Quinases Reguladas por Sinal Extracelular , Receptores Adrenérgicos alfa 1/metabolismo , Transdução de Sinais , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Ativação Enzimática , Receptores ErbB/metabolismo , Células HEK293 , Humanos , MAP Quinase Quinase 1/metabolismo , Mutação , Fosforilação , Domínios Proteicos , Proteína Quinase C/metabolismo , Proteínas Proto-Oncogênicas c-raf/metabolismo , Ratos , Receptores Adrenérgicos alfa 1/efeitos dos fármacos , Receptores Adrenérgicos alfa 1/genética , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Transfecção , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
AIMS: Testicular capsule contractile dysfunctions are recognized to contribute to male infertility, but the influence of sexual maturation and exogenous testosterone on the expression and function of androgen receptor and α1-adrenoceptors on rat testicular capsule is unclear. Here, these two biological parameters were evaluated on testicular capsule from sexually immature and young adult rats treated or not with exogenous testosterone. MAIN METHODS: Male Wistar rats (45- and 60-day-old) were assigned into groups: control (saline 0.9%) or testosterone-treated (propionate testosterone). Testicular capsule was isolated and processed for functional studies, immunohistochemistry, Western blot and RT-PCR studies. KEY FINDINGS: Relative testicular capsule wet weight was not affected by sexual maturation or exogenous testosterone treatment. The expression and immunolocalization of androgen receptor (mRNA and protein) was identified in testicular capsule. Androgen receptor and α1-adrenoceptor (Adra1a, Adra1b, and Adra1d) mRNA levels were similar in testicular capsule from all experimental groups. Functional studies indicated that contractions produced by noradrenaline in testicular capsule from 45- and 60-day-old rats treated or not with testosterone were mainly mediated by α1A- and α1B-adrenoceptors. The L-type Ca(2+) channel blocker nifedipine induced a higher inhibitory effect on noradrenaline induced contractions in testicular capsule from 45- than 60-day-old rats treated with testosterone. SIGNIFICANCE: Molecular studies, immunohistochemistry and pharmacological functional assays used in this study provide evidences of the androgen receptor expression in testicular capsule and that function, and not mRNA and protein expression levels of the α1-adrenoceptor subtypes in this tissue, is differentially influenced by the rat androgen status.
Assuntos
Receptores Adrenérgicos alfa 1/fisiologia , Receptores Androgênicos/biossíntese , Receptores Androgênicos/fisiologia , Maturidade Sexual/fisiologia , Testículo/fisiologia , Testosterona/fisiologia , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo L/efeitos dos fármacos , Masculino , Contração Muscular/efeitos dos fármacos , Nifedipino/farmacologia , Norepinefrina/farmacologia , Tamanho do Órgão/efeitos dos fármacos , Tamanho do Órgão/fisiologia , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Ratos , Ratos Wistar , Receptores Adrenérgicos alfa 1/biossíntese , Testículo/crescimento & desenvolvimento , Testículo/metabolismo , Testosterona/farmacologiaRESUMO
Internalization of G protein-coupled receptors can be triggered by agonists or by other stimuli. The process begins within seconds of cell activation and contributes to receptor desensitization. The Rab GTPase family controls endocytosis, vesicular trafficking, and endosomal fusion. Among their remarkable properties is the differential distribution of its members on the surface of various organelles. In the endocytic pathway, Rab 5 controls traffic from the plasma membrane to early endosomes, whereas Rab 4 and Rab 11 regulate rapid and slow recycling from early endosomes to the plasma membrane, respectively. Moreover, Rab 7 and Rab 9 regulate the traffic from late endosomes to lysosomes and recycling to the trans-Golgi. We explore the possibility that α1B-adrenergic receptor internalization induced by agonists (homologous) and by unrelated stimuli (heterologous) could involve different Rab proteins. This possibility was explored by Fluorescence Resonance Energy Transfer (FRET) using cells coexpressing α1B-adrenergic receptors tagged with the red fluorescent protein, DsRed, and different Rab proteins tagged with the green fluorescent protein. It was observed that when α1B-adrenergic receptors were stimulated with noradrenaline, the receptors interacted with proteins present in early endosomes, such as the early endosomes antigen 1, Rab 5, Rab 4, and Rab 11 but not with late endosome markers, such as Rab 9 and Rab 7. In contrast, sphingosine 1-phosphate stimulation induced rapid and transient α1B-adrenergic receptor interaction of relatively small magnitude with Rab 5 and a more pronounced and sustained one with Rab 9; interaction was also observed with Rab 7. Moreover, the GTPase activity of the Rab proteins appears to be required because no FRET was observed when dominant-negative Rab mutants were employed. These data indicate that α1B-adrenergic receptors are directed to different endocytic vesicles depending on the desensitization type (homologous vs. heterologous).
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Endossomos/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Cálcio/metabolismo , Transferência Ressonante de Energia de Fluorescência , Células HEK293 , Humanos , Lisofosfolipídeos/farmacologia , Norepinefrina/farmacologia , Fosforilação , Transporte Proteico/efeitos dos fármacos , Esfingosina/análogos & derivados , Esfingosina/farmacologiaRESUMO
Several lines of evidence have shown an association of diabetes with a catecholamines' aberrant homeostasis involving a drastic change in the expression of adrenoceptors. This homeostatic alteration includes, among other things, atypical actions of α2 -adrenoceptor agonists within central and peripheral α2 -adrenoceptors (e.g. profound antinociceptive effects in diabetic subjects). Hence, this study investigated the pharmacological profile of the α2 -adrenoceptor subtypes that inhibit the vasopressor sympathetic out-flow in streptozotocin-pre-treated (diabetic) pithed rats. For this purpose, B-HT 933 (up to 30 µg/kg min) was used as a selective α2 -adrenoceptor agonist and rauwolscine as a non-selective α2A/2B/2C -adrenoceptor antagonist; in addition, BRL 44408, imiloxan and JP-1302 were used as subtype-selective α2A -, α2B - and α2C -adrenoceptor antagonists, respectively (all given i.v.). I.v. continuous infusions of B-HT 933 inhibited the vasopressor responses induced by electrical sympathetic stimulation without affecting those by i.v. bolus injections of noradrenaline in both normoglycaemic and diabetic rats. Interestingly, the ED50 for B-HT 933 in diabetic rats (25 µg/kg min) was almost 1-log unit greater than that in normoglycaemic rats (3 µg/kg.min). Moreover, the sympatho-inhibition induced by 10 µg/kg min B-HT 933 in diabetic rats was (i) abolished by 300 µg/kg rauwolscine or 100 and 300 µg/kg BRL 44408; (ii) partially blocked by 1000 µg/kg imiloxan; and (iii) unchanged by 1000 µg/kg JP-1302. Our findings, taken together, suggest that B-HT 933 has a less potent inhibitory effect on the sympathetic vasopressor responses in diabetic (compared to normoglycaemic) rats and that can probably be ascribed to a down-regulation of α2C -adrenoceptors.
Assuntos
Vasos Sanguíneos/inervação , Diabetes Mellitus Experimental/metabolismo , Receptores Adrenérgicos alfa 2/metabolismo , Sistema Nervoso Simpático/metabolismo , Vasoconstrição , Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Vasos Sanguíneos/efeitos dos fármacos , Estado de Descerebração , Diabetes Mellitus Experimental/fisiopatologia , Estimulação Elétrica , Masculino , Ratos Wistar , Receptores Adrenérgicos alfa 2/efeitos dos fármacos , Sistema Nervoso Simpático/fisiopatologia , Vasoconstrição/efeitos dos fármacosRESUMO
A ativação do receptor beta 2 adrenérgico (β2-AR), pelos mediadores químicos do estresse, pode induzir efeitos estimuladores ou inibidores na migração e invasão celular, dependendo do tipo de tumor maligno. A importância deste receptor na evolução do câncer de boca não está totalmente esclarecida. O objetivo deste estudo foi verificar a expressão do β2-AR em linhagens de carcinomas espinocelular de boca (SCC-9 e SCC-25), e investigar o papel da ativação deste receptor pela norepinefrina e de seu bloqueio por um antagonista na migração e invasão destas células neoplásicas. As células SCC-9 e SCC-25 foram investigadas quanto à expressão gênica e proteica do β2-AR, respectivamente, pelo RT-qPCR e pelo Western blot. A migração e a invasão celular foram analisadas pelo ensaio de cicatrização de feridas e pelo sistema de câmeras de invasão Transwell, respectivamente. Diferentes concentrações (0,1; 1 e 10μM) de norepinefrina foram utilizadas para estimular e 1μM de propranolol foi empregado para bloquear os receptores beta adrenérgicos nas células neoplásicas. As diferenças das médias obtidas nos experimentos de invasão e migração de SCC-9 e SCC-25 e da expressão proteica do β2-AR, foram comparadas pelo teste t de Student com nível de significância de 5%. Os resultados mostraram que a expressão gênica e proteica do β2-AR foi verificada em ambas as linhagens de câncer de boca. A concentração de 10μM de norepinefrina inibiu, significativamente (p≤0,05), a migração e invasão celular de SCC-9 e SCC-25, sendo este efeito mais acentuado nas células SCC-25. Além disso, houve uma redução significativa (p≤0,05) do efeito da norepinefrina na migração celular quando os β2-AR foram inibidos pelo propranolol. Adicionalmente, o bloqueio dos β-ARs pelo propranolol reverteu parcialmente o efeito da norepinefrina na capacidade invasiva de SCC-9 e SCC-25. Estes resultados comprovam que a norepinefrina, via ativação do β2-AR, reduziu a migração e a invasão das...
The activation of beta 2 adrenergic receptor (β2-AR), by chemical mediators of stress, can induce stimulatory or inhibitory effects on cell migration and invasion, depending on the type of malignancy. The importance of this receptor in the oral cancer outcome is not fully understood. The aim of this study was to verify β2- AR expression in oral squamous cell carcinoma cell lines (SCC-9 and SCC-25), and to investigate the role of activation of this receptor by norepinephrine and its blockade by an antagonist in migration and invasion of these neoplastic cells. SCC-9 and SCC-25 cells were investigated for gene and protein expression of β2-AR, respectively, by RT-qPCR and Western blot. The cell migration and invasion were analyzed by wound healing assay and Transwell invasion camera system, respectively. Different concentrations (0.1, 1 and 10μM) of norepinephrine were used to stimulate and 1μM propranolol was used to block the beta adrenergic receptors on cancer cells. Differences in mean values of the invasion and migration assays of SCC-9 and SCC-25 and β2-AR protein expression were compared by the Student t test with 5% significance level. The results showed that β2-AR gene and protein expression was verified in both oral cancer cell lines. The concentration of 10μM of norepinephrine inhibited significantly (p≤0.05), cell migration and invasion of SCC-9 and SCC-25, being the most pronounced effect in SCC-25 cells. Furthermore, there was a significant reduction (p≤0.05) of norepinephrine effect on cell migration when the β2-AR was inhibited by propranolol. In addition, blockade of β-ARs by propranolol partially reversed the effect of norepinephrine on the invasiveness of SCC-9 and SCC-25. These results show that norepinephrine via β2-AR activation, reduced the migration and invasion of oral squamous cell carcinoma cells and, therefore, the use of beta-adrenergic receptors agonists could become an adjuvant therapeutic target in the treatment of this malignancy.