Possible Modulation of the Anexiogenic Effects of Vitex Agnus-castus by the Serotonergic System

Objective(s) There is well documented evidence for the increase in widespread use of complementary and alternative medicine in the treatment of physical and psychiatric symptoms and disorders within the populations. In the present study, we investigated the influence of Vitex agnus-castus (vitex) on anxiety-like behaviors of rats. Materials and Methods Elevated plus maze which is one of the methods used for testing anxiety is used in our present study. Rats were orally administrated with vitex for two week. The anxiety test was carried out after two weeks of oral administration of vitex. For evaluating interaction of vitex and serotonergic systems, rats were anaesthetized with ketamine and special cannulas were inserted stereotaxically into the third ventricle (TV) of brain. After ۱ week recovery, the effects of serotonegic agents on anxiety were studied. Results Oral administration of vitex (۱۰۰, ۲۰۰, ۳۰۰ mg/kg) for two weeks induced an anxiogenic-like effect which was shown through specific decreases in the percentages of open arm time (OAT %) and open arm entries (OAE %). Intra-TV infusion of ۵HT۱A receptor agonist, ۸-OH-DPAT (۵, ۱۰ and ۲۵ ng/rat) increased OAT% and OAE%, indicating anxiolytic–like behavior. However, injection of ۵HT۱A receptor antagonist NAN۱۹۰ (۰.۲۵, ۰.۵ and ۱ µg/rat) produced anxiogenic-like behavior. The most effective dose of ۸-OH-DPAT                (۱۰ ng/rat), when co-administered with vitex (۱۰۰, ۲۰۰, ۳۰۰ mg/kg), attenuated the anxiogenic-like effects of vitex significantly. Injection of the less effective dose of NAN۱۹۰ (۰.۵ µg/rat), in combination with vitex (۱۰۰, ۲۰۰, ۳۰۰ mg/kg), potentiate anxiogenic effects of vitex. Conclusions These results illustrate that ۵HT۱A receptor is involved in the anxiogenic effects of vitex.

Keywords:

Anxiety , Rat , Serotonergic system , Vitex agnus-castus