Amibegron hydrochloride (SR 58611A, 0.1 to 0.3 mg/kg, i.p.) potentiates the toxicity produced by yohimbine in mice. Amibegron hydrochloride (0.6 and 2 mg/kg, i.p.) is also active in the learned helplessness model of antidepressant-like activity in rats. However, Amibegron hydrochloride exhibits no effect on the spontaneous locomotor activity of mice at up to 10 mg/kg and of rats at up tp 30 mg/kg^[2]. Amibegron hydrochloride (3 and 10 mg/kg, p.o.) increases the synthesis of 5-HT and tryptophan (Trp) levels in several rodent brain areas such as cortex, hippocampus, hypothalamus, striatum. In addition, Amibegron hydrochloride (10 mg/kg, p.o.) promotes the release of 5-HT in rat prefrontal cortex. Systemic (3 mg/kg, i.v.) or chronic administration of SR58611A (10 mg/kg, p.o.) does not affect the activity of serotonergic neurons in the rat dorsal raphe nucleus^[3].