血管迷走性晕厥和5-羟色胺能系统

5-羟色胺(5-HT)在血管迷走性晕厥(VVS)中的作用备受关注.5-HT是一种神经递质,广泛分布于中枢神经系统,突触后膜有多种5-HT受体,其中,5-HT1A受体介导中枢降压机制,同时能够促进催乳素、促肾上腺皮质激素等释放.短时应用选择性5-羟色胺重摄取抑制剂(SSRI)于药物激发的直立倾斜试验(HUT),能够抑制突触间隙对5-HT的重摄取,突触间隙5-HT浓度升高,诱发晕厥发作,提高HUT试验的敏感性.长期应用SSRI则可下调突触后膜5-HT受体,减弱对中枢5-HT快速变化的反应,从而减弱对交感神经的快速抑制反应,预防晕厥发作.中枢5-羟色胺能系统可能参与了VVS的发病机制,SSRI对VVS的诊断及治疗有重要价值.

Vasovagal syncope and serotonergic system

The role of serotonergic system in vasovagal syncope (VVS) has been more concerned.Serotonin is a kind of neurotransmitter which is widely distributed in central nervous system.There are kinds of serotonergic receptors on postsynaptic membrane,among which 5-HT1A receptors participate in the mechanism of central blood pressure depression and promote the release of hormones such as prolactin and adrenocorticotrophic hormone.Acute administration of selective serotonin reuptake inhibitors (SSRIs) during head-up tilt test (HUT) blocks the reuptake of serotonin in the synapse space and thus increases stimulation of the serotonin receptors,which induces syncope episode.Long-term administration of SSRIs downregulates the postsynaptic serotonergic receptors,thus it weakens the reaction to the rapid change of serotonin concentration, which results in rapid depression of sympathic nerves and prevention of syncope episode.These demonstrate that central serotonergic system may participate in the pathogenesis of VVS and SSRIs are important for the diagnosis and treatment of VVS.