Pharmacological characterization of the α2A-adrenergic receptor inhibiting rat hippocampal CA3 epileptiform activity: comparison of ligand efficacy and potency

Adrenergic receptor system as a pharmacological target in the treatment of epilepsy (Review)

Epilepsy is a complex and common neurological disorder characterized by spontaneous and recurrent seizures, affecting ~75 million individuals worldwide. Numerous studies have been conducted to develop new pharmacological drugs for the effective treatment of epilepsy. In recent years, numerous experimental and clinical studies have focused on the role of the adrenergic receptor (AR) system in the regulation of epileptogenesis, seizure susceptibility and convulsions. α1-ARs (α1A, α1B and α1D), α2-ARs (α2A, α2B and α2C) and β-ARs (β1, β2 and β3), known to have convulsant or anticonvulsant effects, have been isolated. Norepinephrine (NE), the key endogenous agonist of ARs, is considered to play a crucial role in the pathophysiology of epileptic seizures. However, the effects of NE on different ARs have not been fully elucidated. Although the activation of some AR subtypes produces conflicting results, the activation of α1, α2 and β receptor subtypes, in particular, produces anticonvulsant effects. The present review focuses on NE and ARs involved in epileptic seizure formation and discusses therapeutic approaches.

3BDO Alleviates Seizures and Improves Cognitive Function by Regulating Autophagy in Pentylenetetrazol (PTZ)-Kindled Epileptic Mice Model

3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3 H)-one (3BDO) is a mTOR agonist that inhibits autophagy. The main purpose of this study is to investigate the effects of 3BDO on seizure and cognitive function by autophagy regulation in pentylenetetrazol (PTZ)-kindled epileptic mice model. The PTZ-kindled epileptic mice model was used in study. The behavioral changes and electroencephalogram (EEG) of the mice in each group were observed. The cognitive functions were tested by Morris water maze test. The loss of hippocampal neurons was detected by hematoxylin-eosin (HE) staining and immunofluorescence analysis. Immunohistochemistry, western blot and q-PCR were employed to detect the expression of autophagy-related proteins and mTOR in the hippocampus and cortex. Less seizures, increased hippocampal neurons and reduced astrocytes of hippocampus were observed in the 3BDO-treated epileptic mice than in the PTZ-kindled epileptic mice. Morris water maze test results showed that 3BDO significantly improved the cognitive function of the PTZ-kindled epileptic mice. Western blot analyses and q-PCR revealed that 3BDO inhibited the expression of LC3, Beclin-1, Atg5, Atg7 and p-ULK1/ULK1, but increased that of p-mTOR/mTOR, p-P70S6K/P70S6K in the hippocampus and temporal lobe cortex of epileptic mice. Immunohistochemistry and immunofluorescence also showed 3BDO inhibited the LC3 expression and increased the mTOR expression in the hippocampus of epileptic mice. In addition, the autophagy activator EN6 reversed the decrease in the 3BDO-induced autophagy and aggravated the seizures and cognitive dysfunction in the epileptic mice. 3BDO regulates autophagy by activating the mTOR signaling pathway in PTZ-kindled epileptic mice model, thereby alleviating hippocampus neuronal loss and astrocytes proliferation, reducing seizures and effectively improving cognitive function. Therefore, 3BDO may have potential value in the treatment of epilepsy.