Orientador: André Sampaio Pupo / Banca: Ana Lúcia Severo Rodrigues / Banca: Ricardo Luiz Nunes de Souza / Banca: Márcia Gallacci / Banca: Leonardo Resstel Barbosa Moraes / Resumo: A imipramina é antidepressivo tricíclico cujo principal mecanismo é a inibição da captura neuronal de noradrenalina e/ou serotonina, aumentando os níveis sinápticos dessas monoaminas. Além disso, a imipramina, bem como outros antidepressivos tricíclicos, antagonizam os adrenoceptores α1 na mesma faixa de concentração em que inibem o transportador de noradrenalina. Por outro lado, estudos recentes mostraram que a imipramina tem afinidades distintas para os três subtipos de adrenoceptores α1, (α1A, α1B e α1D), ou seja, aproximadamente 25 vezes mais seletiva para α1A em relação aos adrenoceptores α1B e 10 vezes para adrenoceptores α1D em relação aos adrenoceptores α1B. Isso sugere que seu mecanismo de ação possa estar relacionado com essa característica, uma vez que, ao aumentar os níveis sinápticos de noradrenalina, antagoniza α1A e α1D, mas deixa relativamente livre α1B. Então, o objetivo desta tese foi investigar a participação dos adrenoceptores α1A, α1B e α1D no efeito anti-imobilidade da imipramina no teste de suspensão pela cauda em camundongos. Para isso, camundongos foram submetidos ao teste de suspensão pela cauda, com a administração de diversos antagonistas seletivos e não-seletivos para subtipos α1. Os testes foram realizados utilizando a imipramina associada ao prazosin, antagonista não-seletivo para adrenoceptores α1, RS-100329, antagonista seletivo pra α1A, L-765314, seletivo par α1B e BMY-7378, seletivo para α1D. Os animais também foram avaliados com administrações únicas dos antagonistas. Esta tese mostrou que a administração concomitante de prazosin ou o L-765314 reverteram o efeito anti-imobilidade da imipramina. Por outro lado, nem o RS-100329 ou BMY-7378 modificaram o efeito anti-imobilidade da imipramina. Além disso, a administração de apenas o RS-100329 ou BMY-7378 apresentou efeito anti-imobilidade no teste de suspensão pela cauda. Isso indica que o efeito ... / Abstract: Imipramine is a tricyclic antidepressant inhibitor of norepinephrine and serotonin neuronal reuptake. In addition, the imipramine antagonizes α1-adrenoceptors in the same concentration range that inhibited norepinephrine transporter. However, the imipramine has different affinity to α1-adrenoceptor subtypes presenting higher affinity (10-25-fold) towards α1A- and α1D-adrenoceptors compared to α1B-adrenoceptors. This study investigates the α1-adrenoceptor subtypes involved in the anti-immobility effect of imipramine in the tail suspension test in mice. The anti-immobility effect of imipramine was significantly antagonized by the non-subtype-selective α1-adrenoceptor antagonist prazosin. Neither the selective α1A adrenoceptor antagonist RS-100329 nor the selective α1D-adrenoceptor antagonist BMY-7378 changed the anti-immobility effect of imipramine. However, the selective α1B-adrenoceptor antagonist L-765314 antagonized the anti-immobility effect of imipramine. In addition, mice treated only with RS-100329 or BMY-7378 showed reduced immobility time in comparison to mice treated with vehicle, whereas L-765314 increased the immobility time. These results suggests that the α1B-subtype is the main target for the increased levels of norepinephrine caused by imipramine, and that the selective antagonism of α1A- and α1D-adrenoceptors results in anti-immobility effects / Doutor

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published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

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Made available in DSpace on 2015-06-17T19:34:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-09-30. Added 1 bitstream(s) on 2015-06-18T12:47:23Z : No. of bitstreams: 1 000827131_20160930.pdf: 1032389 bytes, checksum: 1ec652e603aca7989376c865a7b92ae6 (MD5) Bitstreams deleted on 2016-10-03T12:15:51Z: 000827131_20160930.pdf,. Added 1 bitstream(s) on 2016-10-03T12:16:37Z : No. of bitstreams: 1 000827131.pdf: 2564151 bytes, checksum: 723e8967f02bfb11f977abb54f8c05f4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Programa de Doutorado Sanduíche no Exterior (PDSE) / O epidídimo é o órgão do sistema reprodutor masculino responsável pela maturação e armazenamento dos espermatozóides. A contração da cauda do epidídimo (CE) é um dos primeiros eventos da fase de emissão seminal da ejaculação e o sistema nervoso autônomo simpático desempenha um papel importante na contração da CE através da ativação de adrenoceptores α1 (α1-ARs). Neste estudo mostramos que a CE expressa α1A-ARs e α1D-ARs e que ambos os receptores contribuem, de um modo complexo, para a contração da CE induzida por agonistas α1. Na ausência de ativação por agonistas o α1D-ARs modula a contração induzida pela ativação de α1A-ARs por agonistas exógenos. Os α1A-ARs da CE não são dessensibilizados pela oximetazolina. Os andrógenos desempenham um papel importante na manutenção da interação entre os α1A/1D-ARs visto que a redução de andrógenos, mas não de estrógenos, pela castração evidencia a presença dos α1D-ARs. A interação complexa entre os 1A/α1D-ARs é discutida no contexto de heterodimerização de receptores visto que mostramos, pela primeira vez, a heterodimerização entre os α1A e α1D-ARs recombinantes humanos / The epididymis is the male reproductive organ responsible for sperm maturation and storage. The contraction of cauda epididymis (CE) during ejaculation is one of the first events of seminal emission phase of ejaculation and the sympathetic nervous system plays a key role in the CE contraction via α1 adrenoceptors (α1-ARs) activation. In this study we show that CE expresses α1A and α1D-ARs and both receptor subtypes contribute in a complex way to the CE contraction induced by α1-ARs agonists. The α1D modulates α1A-ARs induced contraction irrespective of agonist-mediated α1D activation. There is no desensitization of CE α1A-ARs to oxymetazoline. The androgens were shown to play an important role in the maintenance of such α1A/α1D interaction as the androgen deprivation unravels the cryptic functional α1D-ARs. Estrogens had no effect on α1-ARs mediated contraction of CE. The complex α1A/α1D interaction is discussed in the context of receptor heterodimerization as we showed, for the first time, heteromerization of recombinant α1A/α1D-ARs / Programa de Doutorado Sanduíche no Exterior (PDSE): 12355/13-5

Orientador: Luiz Ricardo de Almeida Kiguti / Coorientador: André Sampaio Pupo / Banca: Edson Antunes / Banca: Sandra Cordellini / Banca: Erick José Ramo da Silva / Resumo: O epidídimo é o órgão do sistema reprodutor masculino responsável pela maturação e armazenamento dos espermatozóides. A contração da cauda do epidídimo (CE) é um dos primeiros eventos da fase de emissão seminal da ejaculação e o sistema nervoso autônomo simpático desempenha um papel importante na contração da CE através da ativação de adrenoceptores α1 (α1-ARs). Neste estudo mostramos que a CE expressa α1A-ARs e α1D-ARs e que ambos os receptores contribuem, de um modo complexo, para a contração da CE induzida por agonistas α1. Na ausência de ativação por agonistas o α1D-ARs modula a contração induzida pela ativação de α1A-ARs por agonistas exógenos. Os α1A-ARs da CE não são dessensibilizados pela oximetazolina. Os andrógenos desempenham um papel importante na manutenção da interação entre os α1A/1D-ARs visto que a redução de andrógenos, mas não de estrógenos, pela castração evidencia a presença dos α1D-ARs. A interação complexa entre os 1A/α1D-ARs é discutida no contexto de heterodimerização de receptores visto que mostramos, pela primeira vez, a heterodimerização entre os α1A e α1D-ARs recombinantes humanos / Abstract: The epididymis is the male reproductive organ responsible for sperm maturation and storage. The contraction of cauda epididymis (CE) during ejaculation is one of the first events of seminal emission phase of ejaculation and the sympathetic nervous system plays a key role in the CE contraction via α1 adrenoceptors (α1-ARs) activation. In this study we show that CE expresses α1A and α1D-ARs and both receptor subtypes contribute in a complex way to the CE contraction induced by α1-ARs agonists. The α1D modulates α1A-ARs induced contraction irrespective of agonist-mediated α1D activation. There is no desensitization of CE α1A-ARs to oxymetazoline. The androgens were shown to play an important role in the maintenance of such α1A/α1D interaction as the androgen deprivation unravels the cryptic functional α1D-ARs. Estrogens had no effect on α1-ARs mediated contraction of CE. The complex α1A/α1D interaction is discussed in the context of receptor heterodimerization as we showed, for the first time, heteromerization of recombinant α1A/α1D-ARs / Doutor

In the present study alpha-receptor modulation of coronary flow and cardiac function was examined in exercising dogs, chronically instrumented to measure: circumflex blood flow velocity (CFV), heart rate (HR), global left ventricular function (LVP and dP/dt Max) and regional left ventricular function (%SL and dL/dt (s)max). During exercise, local adrenergic blockade was produced by intracoronary injection of 1.0 mg phentolamine ( anon-specific alpha-antagonist) or .5 mp prazosin. Exercise significantly increased HR, LVP, dP/dt max, CFV, %SL and dL/dt (s)max. Neither alpha-antagonist produced changes in HR, LVP or %SL; however, both phentolamine and prazosin produced significant increses in dP/dtmax, CFV and dL/dt(s)max of the alpha-blocked region, when compared to their exercise level before alpha-blockade. It is suggested that an alpha1-adrenergic vasoconstriction limits coronary vasodilation and, thereby, cardiac function during exercise.

Abstract not available

The morbidity of and the mortality from cardiac disease are higher in diabetic patients. Clinical and experimental evidence suggests that diabetes-induced changes at the level of myocardium can, at least partially, contribute to these cardiac problems. The mechanism(s) involved in this diabetic cardiomyopathy is still unclear, but one defect appears to occur in the alpha₁-adrenoceptor system. Altered myocardial sensitivity and responsiveness to alpha₁-adrenoceptor agonists have been reported in experimental diabetes mellitus. Stimulation of alpha₁-adrenoceptors is known to produce a positive inotropic effect and has been recently shown to stimulate the hydrolysis of phosphoinositides. To evaluate the possibility that the changes in the inotropic responsiveness to alpha₁-adrenoceptor stimulation in the diabetic heart could be linked to altered alpha₁-adrenoceptor-stimulated phosphoinositide turnover and further to the development of diabetic cardiomyopathy, we studied contractility and receptor-stimulated phosphoinositide turnover following norepinephrine (in the presence of propranolol) stimulation in right ventricles from male Wistar rats (200-225 g) which were made diabetic with streptozotocin (55 mg/kg, i.v.). Rats were sacrificed six weeks after the induction of diabetes. Diabetic rats were characterized by decreased body weight gain, hypoinsulinemia, hyperglycemia and hyperlipidemia. Stimulation of alpha₁-adrenoceptors by norepinephrine (in the presence of propranolol) in right ventricles resulted in the formation of inositol monophosphate (measured with a radioisotope method) and inositol 1,4,5-trisphosphate (measured with an inositol 1,4,5-trisphosphate protein binding assay kit) in a time- and concentration-dependent manner in both control and diabetic rats. The increase in inositol 1,4,5-trisphosphate levels preceded the increase in the alpha₁-adrenoceptor-mediated positive inotropic effect. Diabetic hearts showed a greater maximum inotropic response to norepinephrine stimulation and also had a higher inositol 1,4,5-trisphosphate levels. However, with the radioisotope method, a decreased inositol monophosphate formation was shown in diabetic hearts compared with controls. Omega-3 fatty acids supplementation (Promega[symbol omitted], 0.5 ml/kg/day) had no significant effect on the changes in norepinephrine-stimulated inositol monophosphate formation in diabetic hearts. In the presence of the cyclooxygenase inhibitor indomethacin or the thromboxane synthetase inhibitor imidazole, the norepinephrine-stimulated positive inotropic effect and inositol 1,4,5-trisphosphate formation were significantly increased in control hearts, but were unaltered in the hearts from diabetics. The addition of the prostacyclin synthetase inhibitor tranylcypromine reduced the norepinephrine-stimulated positive inotropic effect and inositol 1,4,5-trisphosphate formation only in diabetic hearts and had no effect in the controls. While inositol 1,4,5-trisphosphate may be able to mediate only transient inotropic effects produced by alpha₁-adrenoceptor stimulation, diacylglycerol may provoke a sustained positive inotropic effect by activating slow Ca²⁺ channels through stimulation of protein kinase C. Our results showed that the diabetic hearts had a higher protein kinase C activity in the membrane fraction compared with controls and this was accompanied by a decrease in cytosolic protein kinase C activity. The present study suggests that the increases in inositol 1,4,5-trisphosphate levels and the membrane fraction protein kinase C activity may be implicated in the increased inotropic responsiveness to alpha₁-adrenoceptor stimulation in the hearts of the streptozotocin-diabetic rats. The increases in inositol 1,4,5-trisphosphate level and protein kinase C activity could induce Ca²⁺ overload in the diabetic heart which might be involved in the development of diabetic cardiomyopathy. The results from the omega-3 fatty acid study indicate that the changes in cardiac alpha₁-adrenoceptor-mediated inositol phosphates formation cannot contribute to the previously described improved cardiac function of omega-3 fatty acid-treated streptozotocin-diabetic rats. The nature and physiological significance of the enhanced positive inotropic effect and inositol 1,4,5-trisphosphate formation in the control heart with the addition of indomethacin and imidazole is still unclear. The effect of tranylcypromine may indicate the participation of prostaglandins in mediating the enhanced alpha₁-inotropic effect of norepinephrine in the diabetic heart. / Pharmaceutical Sciences, Faculty of / Graduate