Endogenous and exogenous serotonin, but not sumatriptan, ameliorate seizures and neuroinflammation in the pentylenetetrazole-induced seizure model in rats

ABSTRACT

Background: Epilepsy has neuropsychiatric comorbidities such as depression, bipolar disorder, and anxiety. Drugs that target epilepsy may also be useful for its neuropsychiatric comorbidities. Objective: To investigate the effects of serotonergic modulation on pro-inflammatory cytokines and the seizures in pentylenetetrazole (PTZ)-induced seizure model in rats. Methods: Male Wistar rats were injected intraperitoneally with serotonin, selective serotonin reuptake inhibitor fluoxetine, 5-HT1B/D receptor agonist sumatriptan, or saline 30 min prior to PTZ treatment. Behavioral seizures were assessed by the Racine's scale. Concentrations of IL-1β, IL-6, and TNF-α in serum and brain tissue were determined by ELISA. Results: Serotonin and fluoxetine, but not sumatriptan, alleviated PTZ-induced seizures by prolonging onset times of myoclonic-jerk and generalized tonic-clonic seizures. The anti-seizure effect of fluoxetine was greater than that of serotonin. Likewise, serotonin and fluoxetine, but not sumatriptan, reduced PTZ-induced increases in the levels of IL-1β and IL-6 in both serum and brain tissue. None of the administered drugs including PTZ affected TNF-α concentrations. Conclusions: Our findings suggest that endogenous and exogenous serotonin exhibits anticonvulsant effects by suppressing the neuroinflammation. It seems that 5-HT1B/D receptors do not mediate anticonvulsant and anti-neuroinflammatory effects of serotonin.

RESUMO

Antecedentes: A epilepsia apresenta comorbidades neuropsiquiátricas como depressão, transtorno bipolar e ansiedade. Os medicamentos que visam o tratamento da epilepsia podem ser úteis para a epilepsia e suas comorbidades neuropsiquiátricas. Objetivo: Investigar os efeitos da modulação serotonérgica em citocinas pró-inflamatórias e as convulsões no modelo de convulsão induzida por pentilenotetrazol (PTZ) em ratos. Métodos: Ratos Wistar machos foram injetados intraperitonealmente com serotonina, inibidor seletivo da recaptação da serotonina fluoxetina, sumatriptano agonista do receptor 5-HT1B / D ou solução salina 30 min antes do tratamento com PTZ. As crises comportamentais foram avaliadas pela escala de Racine. As concentrações de IL-1β, IL-6 e TNF-α no soro e tecido cerebral foram determinadas por ELISA. Resultados: A serotonina e a fluoxetina, mas não o sumatriptano, aliviaram as convulsões induzidas por PTZ ao prolongar os tempos de início das convulsões mioclônicas e tônico-clônicas generalizadas. O efeito anticonvulsivo da fluoxetina foi maior do que o da serotonina. Da mesma forma, a serotonina e a fluoxetina, mas não o sumatriptano, reduziram os aumentos induzidos por PTZ nos níveis de IL-1β e IL-6 no soro e no tecido cerebral. Nenhum dos medicamentos administrados, incluindo PTZ, alterou as concentrações de TNF-α. Conclusões: Nossos achados sugerem que a serotonina endógena e exógena exibe efeitos anticonvulsivantes por suprimir a neuroinflamação. Aparentemente, os receptores 5-HT1B / D não medeiam os efeitos anticonvulsivantes e anti-neuroinflamatórios da serotonina.

Keywords:

Serotonin 5-HT1 Receptor Agonists - Fluoxetine - Seizures - Epilepsy - Inflammation

Palavras-chave:

Agonistas do Receptor 5-HT1 de Serotonina - Fluoxetina - Convulsões - Epilepsia - Inflamação

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