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Potential of St. John's wort as antistress medication
Chronic stress is thought to be a risk factor for psychosomatic psychiatric illnesses, such as anxiety and depression disorders . The aim of the present study was to evaluate the mechanisms of action of St. John's wort (SJW) extract (STW 3-VI) in a chronic restraint stress (CRS) model using male Sprague-Dawley rats. Markers of antioxidant capacity, such as SOD, GPx and catalase (CAT) in brain tissues, and plasma hormone levels (ACTH, corticosterone), as well as inflammatory markers such as IL-6, TNF-α and C-reactive protein were determined in addition to behavioral changes. Our first results show that CRS (1h for 21 consecutive days) significantly decreased open field activity in chronically stressed rats, which could be reversed by fluoxetine and SJW treatment (Control unstressed: 3349±433mm/5min; Control stressed: 1740±283mm/5min, p<0.01; fluoxetine 10mg/kg stressed 2949±443mm/5min, p<0.05; SJW 250mg/kg stressed: 2630±390mm/5min, p<0.05; SJW 500mg/kg stressed: 2615±358mm/5min, p<0.05). In addition, CRS significantly decreased thymus and spleen indices in CRS treated controls (Control unstressed: 1.64±0.07; 2.41±0.09 vs. Control stressed: 1.21±0.03; 2.10±0.06, p<0.01). However, treating stressed rats with fluoxetine or SJW extract produced a significant and dose dependent increase in both thymus and spleen indices. In addition, SJW or fluoxetine significantly reduced stress-induced increases in plasma corticosterone and ACTH levels. Furthermore, the administration of fluoxetine prevented the stress-induced increase in IL-6 levels. Compared to fluoxetine, SJW resulted in a small but significant decrease in IL-6 levels. Our data provide new insight into the effects of stress on neuroimmunological and antioxidative parameters as well as into the mechanisms of action of St. John's wort.
References: 1. Ader, R., Cohen, N. (1993) Annu Rev Psychol 44: 53–85.