Abe K, Cho S I, Kitagawa I, Nishiyama N, Saito H
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Brain Res. 1994 Jun 27;649(1-2):7-11. doi: 10.1016/0006-8993(94)91042-1.
Ginseng saponins are known to have various pharmacological actions on the central nervous system. In the present study, we investigated the effects of ginsenoside Rb1 (GRb1) and malonylginsenoside Rb1 (GRb1-m) on the induction of long-term potentiation (LTP) in the dentate gyrus using anesthetized rats. Injection (i.c.v.) of GRb1 did not affect the basal synaptic responses evoked by low-frequency test stimulation, but significantly attenuated the magnitude of LTP induced by strong tetanus (100 pulses at 100 Hz). The inhibitory effect of GRb1 depended on its doses (0.5-50 nmol, i.c.v.). On the other hand, GRb1-m did not affect the LTP induced by the strong tetanus, but facilitated the generation of LTP by the weak tetanus (20 pulses at 60 Hz) that produced only short-lasting potentiation in normal condition. The LTP-facilitating effect of GRb1-m was seen maximally at a dose of 5 nmol (i.c.v.) and diminished at a higher dose (50 nmol, i.c.v.). Since another ginseng saponin ginsenoside Rg1 did not affect the induction of LTP at all, the inhibition and facilitation of LTP induction are probably specific actions of GRb1 and GRb1-m, respectively. This is the first report providing direct evidence that ginseng saponins affect the activity-dependent synaptic plasticity in the brain.
人参皂苷已知对中枢神经系统具有多种药理作用。在本研究中，我们使用麻醉大鼠研究了人参皂苷Rb1（GRb1）和丙二酰人参皂苷Rb1（GRb1-m）对齿状回中长时程增强（LTP）诱导的影响。脑室内注射GRb1不影响低频测试刺激诱发的基础突触反应，但显著减弱了强直刺激（100Hz，100个脉冲）诱导的LTP幅度。GRb1的抑制作用取决于其剂量（0.5-50nmol，脑室内注射）。另一方面，GRb1-m不影响强直刺激诱导的LTP，但促进了弱强直刺激（60Hz，20个脉冲）诱导的LTP的产生，在正常情况下，该弱强直刺激仅产生短暂的增强。GRb1-m的LTP促进作用在剂量为5nmol（脑室内注射）时最大，在较高剂量（50nmol，脑室内注射）时减弱。由于另一种人参皂苷人参皂苷Rg1对LTP的诱导完全没有影响，LTP诱导的抑制和促进作用可能分别是GRb1和GRb1-m的特异性作用。这是第一份提供直接证据表明人参皂苷影响大脑中依赖活动的突触可塑性的报告。
