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Racetams are a class of drugs that share a pyrrolidone nucleus. Some, such as piracetam, are considered nootropics. Some such as oxiracetam and phenylpiracetam are also stimulants. Others such as levetiracetam and seletracetam are anticonvulsants. ==Mechanism== There is no universally accepted mechanism of action for racetams. Racetams generally show negligible affinity for common central nervous system receptors, but modulation of central neurotransmitters, including acetylcholine and glutamate, has been reported. Although aniracetam and nebracetam show affinity for muscarinic receptors, only nefiracetam demonstrates nanomolar interactions. Modification of membrane-located mechanisms of central signal transduction is another hypothesis. Like some ampakines, some racetams such as piracetam and aniracetam are positive allosteric modulators of the AMPA receptor. Racetams are understood to work by activating glutamate receptors that are colocalized with cholinergic receptors, thus increasing the frequency of activation of the latter. Racetams are posited to enhance memory through interaction with cholinergic and glutamate receptors in the central nervous system. The E1R racetam, a methyl analogue of phenylpiracetam, is a positive allosteric modulator of the sigma-1 receptor. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「racetam」の詳細全文を読む スポンサード リンク
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