Chinese medicine Banxia‐houpu decoction regulates c‐fos expression in the brain regions in chronic mild stress model in rats

Abstract Banxia‐houpu decoction is a safe and effective traditional Chinese medicinal formula used in the treatment of mild and manic‐depressive disorders for centuries. There has been increasing interest in its therapeutic application in depression. However, the mechanisms behind behavioural changes are still poorly understood. Chronic mild stress (CMS)‐induced preference behaviour change has been used as a model to predict the clinical efficacy of many types of antidepressant treatment. Both EtOH and water extracts (AE and WE) of Banxia‐houpu decoction exhibited a significantly increased sucrose intake in the CMS model in rats, but there was no effect in unstressed animals. In the present study, it was found that the c‐fos expression in cerebral cortex, hippocampus and striatum corpora were very high in the CMS model in rats. WE and AE at a dose of 130 mg/kg exhibited a significantly decreased c‐fos expression in the cerebral regions in CMS model in rats, respectively. The former was more potent than the latter. However, no significant changes in the c‐fos expression were observed in unstressed rats treated with the decoction. Fluoxetine not only significantly reduced c‐fos expression in all regions in the CMS model in rats, but only showed a marked decrease in c‐fos expression in the hippocampus in unstressed animals. A different molecular mechanism of Banxia‐houpu decoction and fluoxetine may be implied. The cerebral cortex, hippocampus and striatum conpora might be important structural substrates in the central nervous system mediating the section of the Banxia‐houpu decoction on preference behaviour in CMS‐induced rats, and fos protein might be the common substrate of the signal transduction process of the decoction. Copyright © 2004 John Wiley & Sons, Ltd.