The nootropic properties of ginseng saponin Rb1 are linked to effects on anxiety

Abstract

Previous studies have shown that crude ginseng extracts enhance performance on shock-motivated tasks. Whether such performance enhancements are due to memory-enhancing (nootropic) properties of ginseng, or to other non-specific effects such as an influence on anxiety has not been determined. In the present study, we evaluated both the nootropic and anxiolytic effects of the ginseng saponin Rb1. In the first experiment, 80 five-day-old male chicks received intraperitoneal injections of 0, 0.25, 2.5 or 5.0 mg/kg Rb1. Performance on a visual discrimination task was evaluated 15 minutes, 24 and 72 hours later. Acquisition of a visual discrimination task was unaffected by drug treatment, but the number of errors was significantly reduced in the 0.25 mg/kg group during retention trials completed 24 and 72 hours after injection. Animals receiving higher dosages showed trends towards enhancement initially, but demonstrated impaired performance when tested 72 hours later. Rb1 had no effect on response rates or body weight. In the second experiment, 64 five-day-old male chicks received similar injections of Rb1 (0, 0.25, 2.5 or 5.0 mg/kg) and separation distress was evaluated 15 minutes, 24 and 72 hours later. Rb1 produced a change in separation distress that depended on the dose and environmental condition under which distress was recorded. These data suggest that Rb1 can improve memory for a visual discrimination task and that the nootropic effect may be related to changes in anxiety.

Protective effects of ginseng components in a rodent model of neurodegeneration

“…5,6 Rc has been shown to enhance GABA currents in Xenopus oocytes expressing GABA receptors. 18 In additional work, Rb 1 has been shown to have anxiolytic effects, 19 but the mechanism behind this effect is unknown. Rb 1 injected into the lateral ventricle has no effect on basic synaptic transmission.…”

Anti-stress Effects of 20(<i>S</i>)-Protopanaxadiol and 20(<i>S</i>)-Protopanaxatriol in Immobilized Mice

“…[31][32][33][34][35] Of its constituents, ginsenosides Rb1, Rh2, Rg5/Rk mixture, and Rg1 also showed an anxiolytic effect (i.e., mice treated with these ginsenosides increased the time spent in the open arm (OT) or open arm entries (OE) in the EPM test). 14,[36][37][38] However, orally administered protopanaxadiol and protopanaxatriol ginsenosides are metabolized to their aglycones, 20(S)-protopanaxadiol (PPD) and 20(S)-protopanaxatriol (PPT), via compound K and ginsenoside Rh1, respectively, by gut microbiota. [16][17][18][19] Nevertheless, the anxiolytic effects of their aglycones have been not studied.…”

Therapeutic effects of herbal extracts and constituents in animal models of psychiatric disorders

“…Male chicks exhibited a significant reduction of the number of errors during retention trials in a visual discrimination task following intraperitoneal injections of the ginseng saponin Rb1 (0.25-5.0 mg/kg) (Churchill et al, 2002). Ginseng constituents were also effective in reducing stress and anxiety (Churchill et al, 2002;Nguyen et al, 1995). It is well known that the hypothalamic-pituitary-adrenal system plays a role in the physiological and pharmacological actions of P. ginseng.…”

“…The nootropic effects of a variety of P. ginseng extracts and ginsenosides have been shown in aged rats (Jaenicke et al, 1991), SCOP-and ethanol-treated rats (Hsieh et al, 2000b;Lee et al, 2000;Li et al, 1999;Ma et al, 1991), rats with medial prefrontal cortex lesions (Zhao and McDaniel, 1998), SCOPtreated mice (Jin et al, 1999;Li et al, 1999), and ischemic gerbils (Wen et al, 1996). Male chicks exhibited a significant reduction of the number of errors during retention trials in a visual discrimination task following intraperitoneal injections of the ginseng saponin Rb1 (0.25-5.0 mg/kg) (Churchill et al, 2002). Ginseng constituents were also effective in reducing stress and anxiety (Churchill et al, 2002;Nguyen et al, 1995).…”

“…enhancing ACh and neurotrophic activity Churchill et al, 2002;Hsieh et al, 2000b;Jaenicke et al, 1991;Jin et al, 1999;Lee et al, 2000Lee et al, , 2001Li et al, 1999;Ma et al, 1991;Nitta et al, 1995;Petkov et al, 0.25 -5 1994a, 1994bShen et al, 1994;Yabe et al, 2003;Zhang et al, 1994 Z Cheng et al, 1999;Liu et al, 1998;Nomura et al, 1997;Wu et al, 1997 …”