Adaptogens modify stress response by suppressing the increase of p-SAPK, nitric oxide and cortisone in the blood of rabbits

Adaptogens possess anti-fatigue and anti-stress activities that can increase mental and physical working performance against a background of fatigue or stress. The aim of the present study was to ascertain which mediators of stress response are significantly involved in the mechanisms of action of adaptogens, and to determine their relevance as biochemical markers for evaluating anti-stress effects in laboratory animals subjected to immobilisation stress. Basal blood levels of cortisone, testosterone, nitric oxide, prostaglandin E₂, thromboxane B₂, leukotriene B₄, stress-activated protein kinase (SAPK), and phosphorylated-SAPK (p-SAPK/p-JNK) were determined in three groups of rabbits. Group A and B animals were treated orally for 7 days with extracts of Eleutherococcus senticosus (Rupr. & Maxim.) Maxim., Schizandra chinensis (Turcz.) Baill., Panax ginseng C.A. Meyer, Bryonia alba L., Rhodiola rosea L. and active component rhodioloside; group C received only placebo. Ten minutes after the final treatment, group A and C animals were immobilized for 2 hours, and blood levels of markers in rabbits of all groups re-determined. Only p-SAPK, cortisone and nitric oxide increased significantly (200–300% > basal levels) following immobilization stress (group C). However, following repeated administration of adaptogens, basal levels of these markers remained practically unchanged during acute stress (group A). S. chinensis, R. rosea and rhodioloside were the most active inhibitors of p-SAPK formation (group B). It is speculated that the positive effects of adaptogens on mental performance in stress may be associated with the inhibition of p-SARK formation, and that such activity might be beneficial in neurodegenerative disorders associated with loss of neurons in brain regions involved in learning and memory.