RESUMO
AIMS: It is well established that intracellular cAMP contributes to the relaxation of vas deferens smooth muscle. In many tissues, intracellular cAMP is actively transported to the extracellular space, where it exerts regulatory functions, via its metabolite adenosine. These actions take place through the cAMP conversion to adenosine by ectoenzymes, a process called "extracellular cAMP-adenosine pathway". Herein, we investigated whether, in addition to ATP, extracellular cAMP might be an alternative source of adenosine, influencing the contraction of vas deferens smooth muscle. MAIN METHODS: The effects of cAMP, 8-Br-cAMP and adenosine were analyzed in the isometric contractions of rat vas deferens. cAMP efflux was analyzed by measuring extracellular cAMP levels after exposure of vas deferens segments to isoproterenol and forskolin in the presence or absence of MK-571, an inhibitor of MRP/ABCC transporters. KEY FINDINGS: While 8-Br-cAMP, a cell-permeable cAMP analog, induced relaxation of KCl-precontracted vas deferens, the non-permeant cAMP increased the KCl-induced contractile response, which was mimicked by adenosine, but prevented by inhibitors of ecto-5'-nucleotidase or A1 receptors. Our results also showed that isoproterenol and forskolin increases cAMP efflux via an MRP/ABCC transporter-dependent mechanism, since it is inhibited by MK-571. SIGNIFICANCE: Our data show that activation of ß-adrenoceptors and adenylyl cyclase increases cAMP efflux from vas deferens tissue, which modulates the vas deferens contractile response via activation of adenosine A1 receptors. Assuming that inhibition of vas deferens contractility has been proposed as a strategy for male contraception, the extracellular cAMP-adenosine pathway emerges as a potential pharmacological target that should be considered in studies of male fertility.
Assuntos
5'-Nucleotidase , AMP Cíclico , Contração Muscular , Ratos Wistar , Receptor A1 de Adenosina , Ducto Deferente , Masculino , Animais , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/metabolismo , AMP Cíclico/metabolismo , 5'-Nucleotidase/metabolismo , Receptor A1 de Adenosina/metabolismo , Receptor A1 de Adenosina/efeitos dos fármacos , Ratos , Contração Muscular/efeitos dos fármacos , Adenosina/farmacologia , Adenosina/análogos & derivados , Adenosina/metabolismo , Isoproterenol/farmacologia , Músculo Liso/efeitos dos fármacos , Músculo Liso/metabolismo , Colforsina/farmacologiaRESUMO
6-Cyanodopamine is a novel catecholamine released from rabbit isolated heart. However, it is not known whether this catecholamine presents any biological activity. Here, it was evaluated whether 6-cyanodopamine (6-CYD) is released from rat vas deferens and its effect on this tissue contractility. Basal release of 6-CYD, 6-nitrodopamine (6-ND), 6-bromodopamine, 6-nitrodopa, and 6-nitroadrenaline from vas deferens were quantified by LC-MS/MS. Electric-field stimulation (EFS) and concentration-response curves to noradrenaline, adrenaline, and dopamine of the rat isolated epididymal vas deferens (RIEVD) were performed in the absence and presence of 6-CYD and /or 6-ND. Expression of tyrosine hydroxylase was assessed by immunohistochemistry. The rat isolated vas deferens released significant amounts of both 6-CYD and 6-ND. The voltage-gated sodium channel blocker tetrodotoxin had no effect on the release of 6-CYD, but it virtually abolished 6-ND release. 6-CYD alone exhibited a negligible RIEVD contractile activity; however, at 10 nM, 6-CYD significantly potentiated the noradrenaline- and EFS-induced RIEVD contractions, whereas at 10 and 100 nM, it also significantly potentiated the adrenaline- and dopamine-induced contractions. The potentiation of noradrenaline- and adrenaline-induced contractions by 6-CYD was unaffected by tetrodotoxin. Co-incubation of 6-CYD (100 pM) with 6-ND (10 pM) caused a significant leftward shift and increased the maximal contractile responses to noradrenaline, even in the presence of tetrodotoxin. Immunohistochemistry revealed the presence of tyrosine hydroxylase in both epithelial cell cytoplasm of the mucosae and nerve fibers of RIEVD. The identification of epithelium-derived 6-CYD and its remarkable synergism with catecholamines indicate that epithelial cells may regulate vas deferens smooth muscle contractility.
Assuntos
Dopamina , Contração Muscular , Ducto Deferente , Masculino , Animais , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/metabolismo , Ducto Deferente/fisiologia , Contração Muscular/efeitos dos fármacos , Ratos , Dopamina/metabolismo , Dopamina/farmacologia , Ratos Wistar , Norepinefrina/farmacologia , Norepinefrina/metabolismo , Músculo Liso/efeitos dos fármacos , Músculo Liso/metabolismo , Músculo Liso/fisiologia , Estimulação Elétrica , Epinefrina/farmacologia , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Systemic scorpion envenomation is characterized by massive neurotransmitter release from peripheral nerves mediated primarily by scorpion venoms neurotoxins. Tityus bahiensis is one of the medically most important species in Brazil, but its venom pharmacology, especially regarding to peripheral nervous system, is poorly understood. Here, we evaluated the T. bahiensis venom activity on autonomic (sympathetic) neurotransmission by using a variety of approaches, including vas deferens twitch-tension recordings, electrophysiological measurements (resting membrane potentials, spontaneous excitatory junctional potentials and whole-cell patch-clamp), calcium imaging and histomorphological analysis. Low concentrations of venom (≤ 3 µg/mL) facilitated the electrically stimulated vas deferens contractions without affecting postsynaptic receptors or damaging the smooth muscle cells. Transient TTX-sensitive sustained contractions and resting membrane depolarization were mediated mainly by massive spontaneous ATP release. High venom concentrations (≥ 10 µg/mL) blocked the muscle contractions and induced membrane depolarization. In neuronal cells (ND7-23wt), the venom increased the peak sodium current, modified the current-voltage relationship by left-shifting the Nav-channel activation curve, thereby facilitating the opening of these channels. The venom also caused a time-dependent increase in neuronal calcium influx. These results indicate that the sympathetic hyperstimulation observed in systemic envenomation is presynaptically driven, probably through the interaction of α- and ß-toxins with neuronal sodium channels.
Assuntos
Venenos de Escorpião/toxicidade , Escorpiões , Animais , Masculino , Potenciais da Membrana/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/fisiologiaRESUMO
The new glucosyl sarpagan alkaloid designated as 21(R*)-(O-ß-glucosyl)-hydroxy-sarpagan-17-oic acid, along with eleven known alkaloids were isolated from a soluble alkaloidal fraction from the ethanol extract of Rauvolfia ligustrina. Their structures were elucidated by interpretation of spectroscopic data (1D and 2D NMR), HRESIMS experiment, GIAO 13C NMR calculations, and comparison with literature data. All the isolated alkaloids were screened by their neuroinhibitory effects using the electrically stimulated mice vas deferens bioassay. Compounds 1, 2 and 9 presented a potent inhibitory effect in the neurotransmission while 3 and 11 showed an acute neuroexcitatory effect. Compound 10 exhibited a very effective post-synaptic inhibitory activity.
Assuntos
Alcaloides Indólicos/farmacologia , Raízes de Plantas/química , Rauwolfia/química , Transmissão Sináptica/efeitos dos fármacos , Animais , Brasil , Estimulação Elétrica , Técnicas In Vitro , Alcaloides Indólicos/química , Espectroscopia de Ressonância Magnética , Masculino , Camundongos , Estrutura Molecular , Compostos Fitoquímicos/isolamento & purificação , Compostos Fitoquímicos/farmacologia , Extratos Vegetais/química , Ducto Deferente/efeitos dos fármacosRESUMO
Abstract Imposex is the development of male sexual characteristics caused by the toxic effects of some chemicals that acts as an endocrinal disruptor. Antifouling paints contain these chemicals. Cartagena lacks studies to indicate the extent of imposex in its coastal waters. The aim of this study was to determine the prevalence of imposex in the gastropod Stramonita haemastoma in Cartagena, Colombia. Specimens were collected during 2013 from locations of high and low influence of port activity. Morphometric measurements and the frequency of the occurrence of imposex were registered. The comparison among morphometric variables showed statistically significant differences between the two sites studied. Furthermore, the females of the S. haemastoma species presented an imposex frequency of 93.1% in Birds' Island, Cartagena Bay, compared to 31.8% in La Bocana. The relative penis size index or RPLI (10.145 and 3.231) and vas deferens sequence index or VDSI (2.83 and 1.16), showed possible contamination by organotin compounds in both places.
Resumo Imposex é o desenvolvimento de características sexuais masculinas causadas por poluentes tóxicos de alguns produtos químicos que atuam como desreguladores endócrinos. Tintas anti-incrustantes são as que contêm estes produtos químicos. Cartagena carece de estudos para indicar a extensão do imposex nas suas águas costeiras. O objetivo deste estudo foi determinar a prevalência de imposex no gastrópode Stramonita haemastoma em Cartagena, Colômbia. Os espécimes foram coletados durante 2013 de locais de alta e baixa influência da atividade portuária. Foram registradas as medidas morfométricas e a frequência da ocorrência do imposex. A comparação entre as variáveis morfométricas mostrou diferenças estatisticamente significantes entre os dois locais estudados. Além disso, as fêmeas da espécie S. haemastomaapresentaram uma frequência de imposex de 93,1% na Ilha das Aves, Baía das Cartagena, em comparação com 31,8% em La Bocana. O índice do comprimento relativo do pênis ou RPLI (10,145 e 3,231) e o índice da sequência do vaso deferente ou VDSI (2,83 e 1,16), mostraram possível contaminação por compostos organoestânicos em ambos os locais.
Assuntos
Animais , Masculino , Feminino , Compostos Orgânicos de Estanho/toxicidade , Pintura/toxicidade , Transtornos do Desenvolvimento Sexual/induzido quimicamente , Poluentes Químicos da Água/toxicidade , Monitoramento Ambiental/métodos , Gastrópodes/efeitos dos fármacos , Ducto Deferente/efeitos dos fármacos , Poluentes Químicos da Água/análise , ColômbiaRESUMO
Lepidium meyenii, a Peruvian plant growing over 4000 m.a.s.l., has effects on nutrition and fertility. The purpose of this study was to evaluate the sperm count in 105 male mice receiving boiled aqueous extract of yellow maca hypocotyls from different sizes, under different pH conditions and using two different routes of administration. Five mice per group were treated daily for 3 days with vehicle (oral and intraperitoneal) or maca aqueous extracts (5 mg/0.5 ml/day) belonging to the first, second, third and fourth categories, according to their hypocotyl size. On day four, sperm count was evaluated at testis, epididymis and vas deferens. Sperm count was higher in mice receiving maca from the larger sizes (first and second categories). Reduction in maca extract pH increased sperm count, whereas an increase in the pH resulted in a reduction in sperm count. The effect of pH reduction is observed only in maca from the first and second categories. Aqueous extract of maca was effective only after oral administration. In conclusion, the larger size of hypocotyls presented the best biological effect, and the low pH in the extract and the transformation after gastrointestinal passage are both important for its biological action.
Assuntos
Epididimo/efeitos dos fármacos , Lepidium , Extratos Vegetais/farmacologia , Espermatozoides/efeitos dos fármacos , Testículo/efeitos dos fármacos , Ducto Deferente/efeitos dos fármacos , Animais , Masculino , Camundongos , Contagem de Espermatozoides , Espermatogênese/efeitos dos fármacosRESUMO
Imposex is the development of male sexual characteristics caused by the toxic effects of some chemicals that acts as an endocrinal disruptor. Antifouling paints contain these chemicals. Cartagena lacks studies to indicate the extent of imposex in its coastal waters. The aim of this study was to determine the prevalence of imposex in the gastropod Stramonita haemastoma in Cartagena, Colombia. Specimens were collected during 2013 from locations of high and low influence of port activity. Morphometric measurements and the frequency of the occurrence of imposex were registered. The comparison among morphometric variables showed statistically significant differences between the two sites studied. Furthermore, the females of the S. haemastoma species presented an imposex frequency of 93.1% in Birds' Island, Cartagena Bay, compared to 31.8% in La Bocana. The relative penis size index or RPLI (10.145 and 3.231) and vas deferens sequence index or VDSI (2.83 and 1.16), showed possible contamination by organotin compounds in both places.
Assuntos
Transtornos do Desenvolvimento Sexual/induzido quimicamente , Monitoramento Ambiental/métodos , Gastrópodes/efeitos dos fármacos , Compostos Orgânicos de Estanho/toxicidade , Pintura/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Colômbia , Feminino , Masculino , Ducto Deferente/efeitos dos fármacos , Poluentes Químicos da Água/análiseRESUMO
Five new meroterpenoid compounds designed as rel-10ß,11ß-epoxy-2,11-dimethoxy-8α-hydroxy-8aß-methyl-5α,6,7,8,8a,9,10,10aß-octahydro-1,4-anthracendione (1), rel-10ß,11ß-epoxy-8α,5-dihydroxy-2-methoxy-8aß-methyl-5,6,7,8,8a,9,10,10aß-octahydro -1.4-anthracendione (2), rel-1,4,8α-trihydroxy-5-furanyl-2-methoxy-8aß-methyl-6,7,8, 8a,9,10-hexahydro-10-anthracenone (3), rel-10α,11α-epoxy-8α,11ß-dihydroxy-8aß-methyl-5ß,6,7,8,8a,9,10,10aß-octahydro-1,4-anthracenediol (4) and rel-1,4,8α-trihydroxy-5-carboxyethyl-2-methoxy-8aß-methyl-6,7,8,8a,9,10-hexahydro-10-anthra-cenone (5), besides seven (6-12) known compounds were isolated from the heartwood and sapwood ethanol extracts of Cordia oncocalyx. Moreover, the main isolated compounds were screened using the electrically driven mice vas deferens bioassay, which has a rich pharmacological receptors diversity.
Assuntos
Benzoquinonas/química , Cordia/química , Hidroquinonas/química , Contração Muscular/efeitos dos fármacos , Terpenos/química , Animais , Benzoquinonas/isolamento & purificação , Hidroquinonas/isolamento & purificação , Técnicas In Vitro , Masculino , Camundongos , Estrutura Molecular , Terpenos/isolamento & purificação , Ducto Deferente/efeitos dos fármacosRESUMO
It is described that fluoxetine treatment is able to induce ejaculatory disorders. However, the exact mechanism is still not fully understood. Therefore, this study was carried out to further evaluate the anti-ejaculatory effects of fluoxetine, using different approaches (in vitro or in vivo treatments), on the sympathetic neurotransmission of the rat vas deferens. Vas deferens from male Wistar rats were used to check the in vitro effects of fluoxetine 10-6M, 3.10-6M or 10-5M. Animals were also acutely (20mg/kg, i.p. 4h or 24h) or chronically (10mg/kg, i.p., 30days) treated with fluoxetine or drug-free vehicle. The vas deferens from non-treated and treated animals were isolated and mounted in an isolated organ bath for the study of the contractions induced by adrenergic agonists, tyramine, 5-HT, Ca2+ or electrical field stimulation. In vitro or acute treatment with fluoxetine decreased the contraction induced by agonists, Ca2+ or electrical field stimulation. The chronic treatment with fluoxetine decreased the contractions induced agonists, tyramine or Ca2+, but did not modify the contractions induced by electrical field stimulation. We have shown that in vitro or in vivo fluoxetine treatment is able to alter the sympathetic neurotransmission of the rat vas deferens which could be related to alterations in the calcium signalling.
Assuntos
Fluoxetina/administração & dosagem , Simpatolíticos/administração & dosagem , Transmissão Sináptica/efeitos dos fármacos , Ducto Deferente/efeitos dos fármacos , Animais , Cálcio/metabolismo , Avaliação Pré-Clínica de Medicamentos , Ejaculação/efeitos dos fármacos , Ejaculação/fisiologia , Masculino , Ratos Wistar , Simpatomiméticos/farmacologia , Transmissão Sináptica/fisiologia , Fatores de Tempo , Técnicas de Cultura de Tecidos , Ducto Deferente/fisiologiaRESUMO
LINKED ARTICLE: This article is commented on by Michel, M. C., pp. 429-430 of this issue. To view this commentary visit http://dx.doi.org/10.1111/bph.13379. BACKGROUND AND PURPOSE: Mirabegron is the first ß3 -adrenoceptor agonist approved for treatment of overactive bladder syndrome. This study aimed to investigate the effects of ß3 -adrenoceptor agonist mirabegron in mouse urethra. The possibility that mirabegron also exerts α1 -adrenoceptor antagonism was also tested in rat smooth muscle preparations presenting α1A - (vas deferens and prostate), α1D - (aorta) and α1B -adrenoceptors (spleen). EXPERIMENTAL APPROACH: Functional assays were carried out in mouse and rat isolated tissues. Competition assays for the specific binding of [(3) H]prazosin to membrane preparations of HEK-293 cells expressing each of the human α1 -adrenoceptors, as well as ß-adrenoceptor mRNA expression and cyclic AMP measurements in mouse urethra, were performed. KEY RESULTS: Mirabegron produced concentration-dependent urethral relaxations that were shifted to the right by the selective ß3 -adrenoceptor antagonist L-748,337 but unaffected by ß1 - and ß2 -adrenoceptor antagonists (atenolol and ICI-118,551 respectively). Mirabegron-induced relaxations were enhanced by the PDE4 inhibitor rolipram, and the agonist stimulated cAMP synthesis. Mirabegron also produced rightward shifts in urethral contractions induced by the α1 -adrenoceptor agonist phenylephrine. Schild regression analysis revealed that mirabegron behaves as a competitive antagonist of α1 -adrenoceptors in urethra, vas deferens and prostate (α1A -adrenoceptor, pA2 â 5.6) and aorta (α1D -adrenoceptor, pA2 â 5.4) but not in spleen (α1B -adrenoceptor). The affinities estimated for mirabegron in functional assays were consistent with those estimated in radioligand binding with human recombinant α1A - and α1D -adrenoceptors (pKi â 6.0). CONCLUSION AND IMPLICATIONS: The effects of mirabegron in urethral smooth muscle are the result of ß3 -adrenoceptor agonism together with α1A and α1D -adrenoceptor antagonism.
Assuntos
Acetanilidas/farmacologia , Antagonistas de Receptores Adrenérgicos alfa 1/farmacologia , Agonistas de Receptores Adrenérgicos beta 3/farmacologia , Tiazóis/farmacologia , Uretra/efeitos dos fármacos , Aminofenóis/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/fisiologia , Células HEK293 , Humanos , Técnicas In Vitro , Masculino , Camundongos Endogâmicos C57BL , Relaxamento Muscular/efeitos dos fármacos , Relaxamento Muscular/fisiologia , Músculo Liso/efeitos dos fármacos , Músculo Liso/fisiologia , Próstata/efeitos dos fármacos , Próstata/fisiologia , Ratos Wistar , Receptores Adrenérgicos alfa/genética , Receptores Adrenérgicos alfa/fisiologia , Baço/efeitos dos fármacos , Baço/fisiologia , Sulfonamidas/farmacologia , Uretra/fisiologia , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/fisiologiaRESUMO
The propiconazole (Prop) is a fungicide extensively used in agriculture. There are evidences that this compound may cause endocrine disrupting effects. In vitro studies have demonstrated that Prop inhibits the activity of CYP 19 (aromatase), responsible for converting androgens into estrogens and also is an androgen and estrogen receptor antagonist. Therefore, this study evaluated the reproductive toxicity of Prop treatment in male rats. The Wistar rats were divided in three groups and were treated daily, by gavage, with corn oil (control group), propiconazole 4 mg/kg (Prop 4) and 20 mg/kg (Prop 20), from post-natal day 50 to 120. The following were observed: the body weight gain, sexual behavior, testosterone and estradiol plasmatic levels, organs weight, sperm count and morphology and testicular histomorphology. There was an increase in abnormal tail morphology sperm, seminal vesicle and vas deferens weight, and a decrease in estradiol levels in Prop 4 group. Sexual behavior was affected only in the Prop 20 group. These results suggest that Prop treatment induced alterations in some reproductive parameters, what could be related with an endocrine disruption.
Assuntos
Disruptores Endócrinos/toxicidade , Fungicidas Industriais/toxicidade , Reprodução/efeitos dos fármacos , Triazóis/toxicidade , Animais , Forma Celular/efeitos dos fármacos , Estradiol/sangue , Masculino , Tamanho do Órgão , Ratos Wistar , Comportamento Sexual Animal/efeitos dos fármacos , Contagem de Espermatozoides , Espermatozoides/efeitos dos fármacos , Espermatozoides/patologia , Testículo/efeitos dos fármacos , Testículo/metabolismo , Testículo/patologia , Testosterona/sangue , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/metabolismo , Ducto Deferente/patologia , Aumento de Peso/efeitos dos fármacosRESUMO
The effects of acute treatment with sibutramine on the peripheral sympathetic neurotransmission in vas deferens of young rats were still not evaluated. Therefore, we carried out this study in order to verify the effects of acute sibutramine treatment on the neuronal- and exogenous agonist-induced contractions of the young rat vas deferens. Young 45-day-old male Wistar rats were pretreated with sibutramine 6 mg/kg and after 4h the vas deferens was used for experiment. The acute treatment with sibutramine was able to increase the potency (pD2) of noradrenaline and phenylephrine. Moreover, the efficacy (Emax) of noradrenaline was increased while the efficacy of serotonin and nicotine were decreased. The maximum effect induced by a single concentration of tyramine was diminished in the vas deferens from treated group. Moreover, the leftward shift of the noradrenaline curves promoted by uptake blockers (cocaine and corticosterone) and ß-adrenoceptor antagonist (propranolol) was reduced in the vas deferens of treated group. The initial phasic and secondary tonic components of the neuronal-evoked contractions of vas deferens from treated group at the frequencies of 2 Hz were decreased. Moreover, only the initial phasic component at 5 Hz was diminished by the acute treatment with sibutramine. In conclusion, we showed that the acute treatment with sibutramine in young rats was able to affect the peripheral sympathetic nervous system by inhibition of noradrenaline uptake and reduction of the neuronal content of this neurotransmitter, leading to an enhancement of vas deferens sensitivity to noradrenaline.
Assuntos
Ciclobutanos/farmacologia , Sistema Nervoso Simpático/citologia , Sistema Nervoso Simpático/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Ducto Deferente/efeitos dos fármacos , Inibidores da Captação Adrenérgica/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Relação Dose-Resposta a Droga , Estimulação Elétrica , Masculino , Contração Muscular/efeitos dos fármacos , Neurônios/citologia , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Sistema Nervoso Simpático/fisiologia , Ducto Deferente/fisiologiaRESUMO
Histamine is an important modulatory agent of the sympathetic neurotransmission, but its exact action on the testicular capsule or rat vas deferens is not fully understood. The present study sought to further investigate the functional effects of histamine on the neuronal and exogenous noradrenaline-induced contraction of the testicular capsule and rat vas deferens as well as to evaluate the contractile properties of this drug. The testicular capsule or vas deferens from Wistar rats, 3-4 months old, weighing 300-400 g, was isolated and mounted in organ baths for functional experiments. The results indicated that the neuronally evoked contraction of the testicular capsule was affected by histamine (10(-10) to 10(-8) M) with participation of inhibitory (H3 receptors) and excitatory (H1 receptors) receptors. Histamine (10(-7) to 10(-4) M) modulated the field-stimulated vas deferens by excitatory (H2 receptors) and inhibitory (H1 receptors) receptors. Histamine was able to decrease the tonic response for noradrenaline-induced contractions with participation of H1 receptors (testicular capsule) and H3 receptors (vas deferens) followed by nitric oxide generation. At high concentration, histamine exerts contractile effects in both tissues. In the testicular capsule, the histamine-induced contractions were related to H1 receptor activation followed by release of prostaglandins. In contrast, the contractile effects of histamine in the vas deferens were related to H2 receptor activation followed by release of catecholamines from sympathetic nerve endings. Therefore, our results indicate that histamine induced several effects on the sympathetic neurotransmission of rat testicular capsule and vas deferens. These effects are dependent on the concentration used and with participation of multiple histamine receptors.
Assuntos
Histamina/farmacologia , Testículo/efeitos dos fármacos , Ducto Deferente/efeitos dos fármacos , Animais , Estimulação Elétrica , Técnicas In Vitro , Masculino , Óxido Nítrico/fisiologia , Norepinefrina/farmacologia , Ratos Wistar , Receptores Histamínicos/fisiologia , Sistema Nervoso Simpático/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Testículo/fisiologia , Ducto Deferente/fisiologiaRESUMO
To assess the role of the P2X1 receptors (P2X1R) in the longitudinal and circular layers of the human vas deferens, ex vivo-isolated strips or rings were prepared from tissue biopsies to record isometric contractions. To ascertain its membrane distribution, tissue extracts were analyzed by immunoblotting following sucrose gradient ultracentrifugation. ATP, alpha,beta-methylene ATP, or electrical field stimulation elicited robust contractions of the longitudinal layer but not of the circular layer which demonstrated inconsistent responses. Alpha,beta-methylene ATP generated stronger and more robust contractions than ATP. In parallel, prostatic segments of the rat vas deferens were examined. The motor responses in both species were not sustained but decayed within the first minute, showing desensitization to additional applications. Cross-desensitization was established between alpha,beta-methylene ATP or ATP-evoked contractions and electrical field stimulation-induced contractions. Full recovery of the desensitized motor responses required more than 30 min and showed a similar pattern in human and rat tissues. Immunoblot analysis of the human vas deferens extracts revealed a P2X1R oligomer of approximately 200 kDa under nonreducing conditions, whereas dithiothreitol-treated extracts showed a single band of approximately 70 kDa. The P2X1R was identified in ultracentrifugation fractions containing 15%-29% sucrose; the receptor localized in the same fractions as flotillin-1, indicating that it regionalized into smooth muscle lipid rafts. In conclusion, ATP plays a key role in human vas deferens contractile responses of the longitudinal smooth muscle layer, an effect mediated through P2X1Rs.
Assuntos
Trifosfato de Adenosina/farmacologia , Microdomínios da Membrana/metabolismo , Contração Muscular , Músculo Liso/fisiologia , Receptores Purinérgicos P2X1/fisiologia , Ducto Deferente/fisiologia , Adulto , Idoso , Animais , Estimulação Elétrica , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Transporte Proteico , Ratos , Ratos Sprague-Dawley , Receptores Purinérgicos P2X1/metabolismo , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/metabolismoRESUMO
It is well established that reduction of Ca2+ influx through L-type voltage-dependent Ca2+ channel (L-type VDCC), or increase of cytosolic cAMP concentration ([cAMP]c), inhibit contractile activity of smooth muscles in response to transmitters released from sympathetic nerves. Surprisingly, in this work we observed that simultaneous administration of L-type VDCC blocker (verapamil) and [cAMP]c enhancers (rolipram, IBMX and forskolin) potentiated purinergic contractions evoked by electrical field stimulation of rat vas deferens, instead of inhibiting them. These results, including its role in sympathetic transmission, can be considered as a "calcium paradox". On the other hand, this potentiation was prevented by reduction of [cAMP]c by inhibition of adenylyl cyclase (SQ 22536) or depletion of Ca2+ storage of sarco-endoplasmic reticulum by blockade of Ca2+ reuptake (thapsigargin). In addition, cytosolic Ca2+ concentration ([Ca2+]c) evaluated by fluorescence microscopy in rat adrenal medullary slices was significantly reduced by verapamil or rolipram. In contrast, simultaneous incubation of adrenal slices with these compounds significantly increased [Ca2+]c. This effect was prevented by thapsigargin. Thus, a reduction of [Ca2+]c due to blockade of Ca2+ influx through L-type VDCC could stimulate adenylyl cyclase activity increasing [cAMP]c thereby stimulating Ca2+ release from endoplasmic reticulum, resulting in augmented transmitter release in sympathetic nerves and contraction.
Assuntos
AMP Cíclico/metabolismo , Músculo Liso/metabolismo , Adenilil Ciclases/metabolismo , Animais , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo L/química , Canais de Cálcio Tipo L/metabolismo , Inibidores Enzimáticos/farmacologia , Masculino , Modelos Biológicos , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Músculo Liso/efeitos dos fármacos , Ratos , Ratos Wistar , Tapsigargina/farmacologia , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/fisiologiaRESUMO
BACKGROUND: Cimetidine, histamine H2 receptors antagonist, has caused adverse effects on the male hormones and reproductive tract due to its antiandrogenic effect. In the testes, peritubular myoid cells and muscle vascular cells death has been associated to seminiferous tubules and testicular microvascularization damages, respectively. Either androgen or histamine H2 receptors have been detected in the mucosa and smooth muscular layer of vas deferens. Thus, the effect of cimetidine on this androgen and histamine-dependent muscular duct was morphologically evaluated. METHODS: The animals from cimetidine group (CMTG; n=5) received intraperitoneal injections of 100 mg/kg b.w. of cimetidine for 50 days; the control group (CG) received saline solution. The distal portions of vas deferens were fixed in formaldehyde and embedded in paraffin. Masson´s trichrome-stained sections were subjected to morphological and the following morphometrical analyzes: epithelial perimeter and area of the smooth muscular layer. TUNEL (Terminal deoxynucleotidyl-transferase mediated dUTP Nick End Labeling) method, NF-kB (nuclear factor kappa B) and AR (androgen receptors) immunohistochemical detection were also carried out. The birefringent collagen of the muscular layer was quantified in picrosirius red-stained sections under polarized light. The muscular layer was also evaluated under Transmission Electron Microscopy (TEM). RESULTS: In CMTG, the mucosa of vas deferens was intensely folded; the epithelial cells showed numerous pyknotic nuclei and the epithelial perimeter and the area of the muscular layer decreased significantly. Numerous TUNEL-labeled nuclei were found either in the epithelial cells, mainly basal cells, or in the smooth muscle cells which also showed typical features of apoptosis under TEM. While an enhanced NF-kB immunoexpression was found in the cytoplasm of muscle cells, a weak AR immunolabeling was detected in these cells. In CMTG, no significant difference was observed in the birefringent collagen content of the muscular layer in comparison to CG. CONCLUSIONS: Cimetidine induces significant damages in the epithelium; a possible antiandrogenic effect on the basal cells turnover should be considered. The cimetidine-induced muscle cells apoptosis confirms the susceptibility of these cells to this drug. The parallelism between enhanced cytoplasmic NF-kB immunolabeling in the damaged muscular tissue and muscle cell apoptosis suggests that this drug may avoid the translocation of NF-kB to the nucleus and interfere in the control of NF-kB-mediated smooth muscle cell apoptosis. The decreased immunoexpression of ARs verified in the damaged muscular tissue reinforces this possibility.
Assuntos
Apoptose/efeitos dos fármacos , Cimetidina/farmacologia , Músculo Liso/efeitos dos fármacos , NF-kappa B/metabolismo , Receptores Androgênicos/metabolismo , Ducto Deferente/efeitos dos fármacos , Animais , Colágeno/metabolismo , Citoplasma/efeitos dos fármacos , Citoplasma/metabolismo , Epitélio/efeitos dos fármacos , Epitélio/metabolismo , Epitélio/patologia , Antagonistas dos Receptores H2 da Histamina/farmacologia , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Masculino , Microscopia Eletrônica de Transmissão , Músculo Liso/metabolismo , Músculo Liso/ultraestrutura , Ratos , Ducto Deferente/metabolismo , Ducto Deferente/patologiaRESUMO
Imposex, a syndrome characterized by the appearance of a penis and/or vas deferens in female gastropods due the presence of organotins in environment, is still observed in Brazilian gastropod populations, as in other countries, even after the tributyltin (TBT) ban. Nevertheless, the progressive controls on the use of organotins in antifouling systems at national and international levels and the consequent reduction of their environmental concentrations have led to changes in the characteristics of imposex development observed in Stramonita haemastoma. Populations of this species were analyzed on the coast of Rio de Janeiro (Brazil) between 2007 and 2008, and the developmental pathways associated with the syndrome were identified. Compared with previous works, it was noted that imposex expression was reduced in most of Guanabara Bay. Aphallic imposex development, on the other hand, showed a marked increase. The pathways of imposex development were also evaluated in a temporal data series from a fixed sampling station at Vermelha beach, and the incidence of aphallic imposex development was found to show a marked increase from 1998 onward. Furthermore, the observation of either the presence or absence of a penis in imposex-affected females may indicate that penis development is related to the contaminant exposure level and that the decreasing TBT concentrations in the local environment result in the predominance of an aphallic route of imposex development. These findings support the idea that imposex female aphally in this species could be a dose-dependent response, rather than a genetic anomaly.
Assuntos
Gastrópodes/efeitos dos fármacos , Compostos Orgânicos de Estanho/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Feminino , Masculino , Compostos de Trialquitina/toxicidade , Ducto Deferente/efeitos dos fármacosRESUMO
Previous studies conducted in our laboratory indicated that administration of amphetamine, fluoxetine or sibutramine affects the sympathetic nervous system of the rat vas deferens. Therefore, our goal was to verify the role of calcium in vasa deferentia from young rats pretreated with a single dose of these drugs. Young 40-day-old male Wistar rats were pretreated with amphetamine 3 mg/kg, fluoxetine 10 mg/kg or sibutramine 6 mg/kg for 4 h before the experiments. CaCl(2) (10 mM) was used to induce contraction through time-effect curves in calcium-free solution to measure phasic and tonic components. We also evaluated the calcium-induced fluorescence of vas deferens cut into thin slices. In rats pretreated with amphetamine, we found an increase of the tonic contraction component which was reduced by verapamil. The phasic and tonic responses were increased in the group treated with fluoxetine, but only the tonic response was more sensitive to the antagonism by verapamil. The group treated with sibutramine showed an increase of phasic response whereas the tonic component was decreased. In this group an increase of the affinity for verapamil antagonism was found. In the calcium fluorescence study it was observed that the group treated with amphetamine, fluoxetine or sibutramine showed higher basal Ca(2+) fluorescence after stimulus with KCl (70 mM), noradrenaline (10(-4)M) or acetylcholine (10(-4)M). In all pretreated groups the calcium fluorescence was diminished by nifedipine 10(-7)M. Therefore, the pretreatment with amphetamine, fluoxetine or sibutramine seems to affect the calcium contractility and homeostasis in young rat vas deferens.
Assuntos
Cálcio/metabolismo , Fármacos do Sistema Nervoso Central/farmacologia , Citosol/efeitos dos fármacos , Citosol/metabolismo , Contração Muscular/efeitos dos fármacos , Ducto Deferente/citologia , Ducto Deferente/fisiologia , Anfetamina/farmacologia , Animais , Ciclobutanos/farmacologia , Fluoxetina/farmacologia , Homeostase/efeitos dos fármacos , Técnicas In Vitro , Masculino , Músculo Liso/citologia , Músculo Liso/efeitos dos fármacos , Músculo Liso/fisiologia , Ratos , Ratos Wistar , Fatores de Tempo , Ducto Deferente/efeitos dos fármacosRESUMO
The nitric oxide-cGMP signaling pathway modulates the ejaculatory functions. The nitric oxide (NO)-independent soluble guanylate cyclase haem-dependent stimulator BAY 41-2272 potently relaxes different types of smooth muscles. However, no study investigated its effects in vas deferens smooth muscle. Therefore, we designed experiments to evaluate the in vitro relaxing responses of vas deferens to BAY 41-2272. The effects of prolonged oral intake with BAY 41-2272 in vas deferens contractions of rats treated chronically with the NO synthase inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME) were also investigated. BAY 41-2272 (0.001-100 µM) produced concentration-dependent relaxations in the prostatic and epididymal portions of vas deferens, an effect markedly reduced by the soluble guanylate cyclase inhibitor ODQ (100 µM). BAY 41-2272 significantly increased cGMP levels that were fully prevented by ODQ. In separate protocols, rats received L-NAME (20mg/rat/day) concomitantly with BAY 41-2272 (10mg/kg/day, 4 weeks), after which vas deferens contractions to electrical-field stimulation and noradrenaline were achieved. Electrical-field stimulation (1-32 Hz) evoked frequency-dependent contractions that were significantly enhanced in L-NAME-treated rats. Co-treatment with BAY 41-2272 fully reversed the increased contractile responses in L-NAME group. Noradrenaline (0.01-100 µM)-induced contractions were also greater in L-NAME-treated rats, and that was normalized by BAY 41-2272. In conclusion, BAY 41-2272 potently relaxes in vitro rat vas deferens smooth muscle and elevates the cGMP levels in an ODQ-sensitive manner. Moreover, prolonged oral intake with BAY 41-2272 restores the enhanced contractile vas deferens activity in rats treated with L-NAME. NO-independent soluble guanylate cyclase stimulators may be an alternative treatment for premature ejaculation.
Assuntos
Músculo Liso/efeitos dos fármacos , Músculo Liso/fisiologia , Pirazóis/farmacologia , Piridinas/farmacologia , Receptores Citoplasmáticos e Nucleares/agonistas , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/fisiologia , Animais , GMP Cíclico/biossíntese , Estimulação Elétrica , Guanilato Ciclase , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/metabolismo , Óxido Nítrico/metabolismo , Norepinefrina/farmacologia , Ratos , Ratos Wistar , Guanilil Ciclase Solúvel , Fatores de Tempo , Ducto Deferente/metabolismoRESUMO
INTRODUCTION: Premature ejaculation is one of the most common male sexual dysfunctions. Current pharmacological treatments involve reduction in penile sensitivity by local anesthetics or increase of ejaculatory threshold by selective serotonin reuptake inhibitors. α1-Adrenoceptors (α1-ARs) and L-type calcium channels are expressed in the smooth muscles of the male reproductive tract, and their activations play an important role in the physiological events involved in the seminal emission phase of ejaculation. AIM: To evaluate if the inhibition of the contractility of the vas deferens and seminal vesicle by α1-AR antagonism or the L-type calcium channel blockade can delay ejaculation. METHODS: The effects of the α1-AR antagonist tamsulosin and of the L-type calcium channel blockers, nifedipine and (S)-(+)-niguldipine, on contractions induced by norepinephrine in the rat vas deferens and seminal vesicles in vitro and on the ejaculation latency of male rats in behavioral mating tests were evaluated. MAIN OUTCOME MEASURE: Tension development of vas deferens and seminal vesicles in response to norepinephrine in vitro and behavioral mating parameters were quantified. RESULTS: Tension development of vas deferens and seminal vesicle to α1-AR activation was significantly inhibited by tamsulosin, nifedipine, and (S)-(+)-niguldipine. Tamsulosin displayed insurmountable antagonism of contractions induced by norepinephrine in the rat vas deferens and seminal vesicle. Ejaculation latency of male rats was not modified by tamsulosin, nifedipine, or (S)-(+)-niguldipine; however, both the number and weight of the seminal plugs recovered from female rats mated with male rats treated with tamsulosin were significantly reduced. CONCLUSION: Seminal emission impairment by inhibition of vas deferens or seminal vesicle contractility by L-type calcium channel blockade or α1-AR antagonism is not able to delay the ejaculation.