In vivo and in vitro effect of imipramine and fluoxetine on Na+, K+-ATPase activity in synaptic plasma membranes from the cerebral cortex of rats

The effects of in vivo chronic treatment and in vitro addition of imipramine, a tricyclic antidepressant, or fluoxetine, a selective serotonin reuptake inhibitor, on the cortical membrane-bound Na+,K+- ATPase activity were studied. Adult Wistar rats received daily intraperitoneal injections of 10 mg/kg of imipramine or fluoxetine for 14 days. Twelve hours after the last injection rats were decapitated and synaptic plasma membranes (SPM) from cerebral cortex were prepared to determine Na+,K+-ATPase activity. There was a significant decrease (10%) in enzyme activity after imipramine but fluoxetine treatment caused a significant increase (27%) in Na+,K+-ATPase activity compared to control (P<0.05, ANOVA; N = 7 for each group). When assayed in vitro, the addition of both drugs to SPM of naive rats caused a dose-dependent decrease in enzyme activity, with the maximal inhibition (60-80%) occurring at 0.5 mM. We suggest that a) imipramine might decrease Na+,K+-ATPase activity by altering membrane fluidity, as previously proposed, and b) stimulation of this enzyme might contribute to the therapeutic efficacy of fluoxetine, since brain Na+,K+-ATPase activity is decreased in bipolar patients

Efeito da administração crônica de imipramina sobre a atividade da Na+, K+ ATPase cerebral de ratos

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In vivo and in vitro effect of imipramine and fluoxetine on Na+, K+-ATPase activity in synaptic plasma membranes from the cerebral cortex of rats

The effects of in vivo chronic treatment and in vitro addition of imipramine, a tricyclic antidepressant, or fluoxetine, a selective serotonin reuptake inhibitor, on the cortical membrane-bound Na+,K+- ATPase activity were studied. Adult Wistar rats received daily intraperitoneal injections of 10 mg/kg of imipramine or fluoxetine for 14 days. Twelve hours after the last injection rats were decapitated and synaptic plasma membranes (SPM) from cerebral cortex were prepared to determine Na+,K+-ATPase activity. There was a significant decrease (10%) in enzyme activity after imipramine but fluoxetine treatment caused a significant increase (27%) in Na+,K+-ATPase activity compared to control (P<0.05, ANOVA; N = 7 for each group). When assayed in vitro, the addition of both drugs to SPM of naive rats caused a dose-dependent decrease in enzyme activity, with the maximal inhibition (60-80%) occurring at 0.5 mM. We suggest that a) imipramine might decrease Na+,K+-ATPase activity by altering membrane fluidity, as previously proposed, and b) stimulation of this enzyme might contribute to the therapeutic efficacy of fluoxetine, since brain Na+,K+-ATPase activity is decreased in bipolar patients

Neurobiologia do transtorno de humor bipolar e tomada de decisão na abordagem psicofarmacológica

O Transtorno do Humor Bipolar (THB) caracteriza-se por oscilações do humor que causam prejuízos significativos no âmbito biopsicossocial. O interesse da comunidade científica por este transtorno vem aumentando nos últimos cinco anos em função de sua crescente prevalência associada ao refinamento diagnóstico, à ampliação do arsenal terapêutico e ao conhecimento dos avanços nas pesquisas da neurobiologia do transtorno. A presente revisão aborda questões diagnosticas e terapêuticas aplicadas à neurobiologia dos THB, relacionando-as diretamente à terapêutica dos quadros de mania, hipomania, estados mistos, depressão bipolar e ciclagem rápida, da infância à idade adulta. São revisados criticamente importantes estudos realizados com diferentes fármacos potencialmente eficazes como estabilizadores do humor, nos diversos subdiagnósticos do THB. São analisados fármacos, tais como o lítio, anticonvulsivantes, antipsicóticos, benzodiazepínicos, bloqueadores dos canais de cálcio e hormônio tireoideo, bem como as possíveis bases biológicas para seus efeitos terapêuticos. Em síntese, este trabalho aborda os avanços da psicofarmacologia cuja eficácia é comprovada nos subtipos do THB, procurando relacioná-los com a neurobiologia deste transtorno.Bipolar Disorder (BD) is characterized by mood swings that cause significant impairment in social, occupational, or other areas of functioning. During the last years, new insights have been provided in the diagnosis, etiology, neurobiological basis and treatment of bipolar disorder. This paper emphasizes recent studies related to some diagnostic and therapeutic aspects during manic episode, hypomanic, mixed episode, bipolar depression and rapid cycling, in children, adolescents and adults. Studies using proposed mood stabilizers, which present adequate metodological basis, including double–blind, controlled studies and which presented a significant number of patients were included and critically evaluated in this revision. Drugs such as the lithium, anticonvulsants, antipsychotics, benzodiazepines, calcium channels blockers and thyroid augmentation are proposed to be effective in certain diagnostic profiles. The possible biological bases for these drugs therapeutic effects are also revised. In summary, this article focuses on recent and important psychopharmacological progresses on the treatment of BD subtypes. Furthermore, the revision presents possible biological basis to explain the therapeutic profile of these drugs