study of the the anxiolytic effects of fennel and possible roles of both gabaergic system and estrogen receptors in these effects in adult female rat

introduction: fennel is rich in phytoestrogens and is used for estrogen deficiency disorders. estrogens affect anxiety through neurochemical systems such as gaba-a receptors. in this study the effects of fennel on gaba-a and estrogen receptors in anxiety were investigated. methods: adult female wistar rats weighing (180±20 g) were divided into 8 groups. groups received saline, fennel (200, 500, 750 mg/kg), tamoxifen (15 mg/kg) + fennel (500 mg/kg), picrotoxin (1 mg/kg) + fennel (500 mg/kg). a control group was also used. elevated plus maze was used for evaluation of anxiety by measuring the time spent in the open arm. all drugs were administered intraperitoneally. results: the results showed that fennel only at the dose of 500 mg/kg had significant anxiolytic effects and increased the time spent in open arms (p<0.01). picrotoxin (gaba-a antagonist) significantly prevented anxiolytic effect of 500 mg/kg of fennel (p<0.001). tamoxifen, an estrogen receptor antagonist, also abolished the anxiolytic effect of fennel (p<0.001). conclusion: fennel reduced anxiety in rats and picrotoxin, a non-competitive antagonist of gaba-a receptors, as well as tamoxifen, an antagonist/agonist of estrogen receptors, reduced this anxiolytic effect. thus fennel as a herbal drug seems to have an anxiolytic effect and it probably acts through gaba-a and estrogen receptors.