Single prolonged stress (SPS), a rat model of post-traumatic stress disorder (PTSD), induces alterations in the hypothalamic-pituitary-adrenal axis. Korean red ginseng, whose major active component is ginsenoside Rb1 (GRb1), is one of the widely used traditional anxiolytics. However, the efficacy of GRb1 in alleviating PTSD-associated anxiety-like abnormalities has not been investigated. The present study used several behavioral tests to examine the effects of GRb1 on symptoms of anxiety in rats after SPS exposure and on the central noradrenergic system. Male Sprague-Dawley rats received GRb1 (10 or 30 mg/kg, i.p., once daily) during 14 days of SPS. Daily GRb1 (30 mg/kg) administration significantly increased the number and duration of open-arm visits in the elevated plus maze (EPM) test, reduced the anxiety index, increased the risk assessment, reduced grooming behaviors in the EPM test, and increased the total number of line crossings of an open field after SPS. The higher dose of GRb1 also blocked SPS-induced decreases in hypothalamic neuropeptide Y expression, increases in locus coeruleus tyrosine hydroxylase expression, and decreases in hippocampal mRNA expression of brain-derived neurotrophic factor. These findings suggest that GRb1 has anxiolytic-like effects on both behavioral and biochemical symptoms similar to those observed in patients with PTSD.
Keywords: Anxiety; Ginsenoside Rb1; Post-traumatic stress disorder; Single prolonged stress; Tyrosine hydroxylase.