Involvement of the Cerebral Monoamine Neurotransmitters System in Antidepressant-Like Effects of a Chinese Herbal Decoction, Baihe Dihuang Tang, in Mice Model

Baihe Dihuang Tang (BDT) is a renowned Chinese herbal formula which is commonly used for treating patients with mental instability, absentmindedness, insomnia, deficient dysphoria, and other psychological diseases. These major symptoms closely associated with the depressive disorders. BDT was widely popular use for treating emotion-thought disorders for many years in China. In the present study, the antidepressant-like effect of BDT in mice was investigated by using the forced swim test (FST) and the tail suspension test (TST). The underlying mechanism was explored by determining the effect of BDT on the level of cerebral monoamine neurotransmitters. BDT (9 and 18 g/kg, p.o. for 14 days) administration significantly reduced the immobility time in both the FST and the TST without changing locomotion in the open field-test (OFT). Moreover, BDT treatment at the dose of 18 g/kg inhibited reserpine-induced ptosis. Meanwhile, BDT enhanced 5-HT and NA levels in mouse cerebrum as well as decreased the ratio of 5-HT compared to its metabolite, 5-HIAA, (turnover, 5-HIAA/5-HT) after TST. The results demonstrated that the antidepressant-like effect of BDT is mediated, at least partially, via the central monoaminergic neurotransmitter system.