Shim I, Javaid J I, Kim S E
Graduate School of East-West Medical Science, Kyung Hee University, Seoul, Korea.
Planta Med. 2000 Dec;66(8):705-8. doi: 10.1055/s-2000-9777.
We investigated the effect of ginseng total saponin (GTS) on nicotine-induced dopamine (DA) release in the striatum of freely moving rats using an in vivo microdialysis technique. In order to further characterize the mechanism by which GTS affects DA release, the effect of GTS on K(+)-induced DA release was also examined. Local infusion of nicotine (1, 5, and 10 mM) into the striatum produced a dose-dependent increase in extracellular DA in dialysate samples (maximal response = 154.0 +/- 10.8%, 308.1 +/- 55.7%, and 499.9 +/- 77.9% over basal levels, respectively). GTS (100 mg/kg i.p.) had no effect on basal levels of extracellular DA. However, GTS inhibited maximal DA release induced by intrastriatal infusion of nicotine (1, 5, and 10 mM) by 35.3%, 36.6%, and 58.5%, respectively. Intra-striatal infusion of high K+ solution (100 mM) produced an increase in extracellular DA in the striatum (maximal response = 796.6 +/- 98.8% over basal levels). However, GTS had no effect on the K(+)-induced increase in extracellular DA. The present study demonstrated that GTS inhibited striatal DA release stimulated by local infusion of nicotine. This may reflect the blocking effect of GTS on the striatum-related behavior induced by nicotine as well as other psychostimulants. The results also suggest that GTS may act on presynaptic nicotinic acetylcholine receptors or receptor-operated Na+ channels in dopaminergic nerve terminals, but not on voltage-sensitive ion channels.
我们使用体内微透析技术，研究了人参总皂苷（GTS）对自由活动大鼠纹状体中尼古丁诱导的多巴胺（DA）释放的影响。为了进一步阐明GTS影响DA释放的机制，还检测了GTS对K⁺诱导的DA释放的作用。向纹状体内局部注入尼古丁（1、5和10 mM），使透析液样本中的细胞外DA呈剂量依赖性增加（最大反应分别比基础水平高154.0±10.8%、308.1±55.7%和499.9±77.9%）。GTS（100 mg/kg腹腔注射）对细胞外DA的基础水平无影响。然而，GTS分别抑制了纹状体内注入尼古丁（1、5和10 mM）诱导的最大DA释放的35.3%、36.6%和58.5%。向纹状体内注入高K⁺溶液（100 mM），使纹状体中的细胞外DA增加（最大反应比基础水平高796.6±98.8%）。然而，GTS对K⁺诱导的细胞外DA增加无影响。本研究表明，GTS抑制了局部注入尼古丁刺激的纹状体DA释放。这可能反映了GTS对尼古丁以及其他精神兴奋剂诱导的与纹状体相关行为的阻断作用。结果还表明，GTS可能作用于多巴胺能神经末梢的突触前烟碱型乙酰胆碱受体或受体操纵的Na⁺通道，但不作用于电压敏感性离子通道。
