Tanshinone IIA Improves Depression-like Behavior in Mice by Activating the ERK-CREB-BDNF Signaling Pathway

Depression is a serious global affective disorder and one of the most common neurological diseases. Tanshinone IIA (TSA) is the mainly active constituent of Salvia miltiorrhiza and has diverse biological effects, including anti-inflammatory and antioxidant effects and significant neuroprotective effects against cerebral ischemia and Alzheimer's disease. However, whether TSA has an antidepressant effect remains unknown. The present study attempted to explore the antidepressant effects and the mechanism of TSA by examining the brain-derived neurotrophic factor (BDNF) expression in the hippocampus of depressive mice. The tail suspension test (TST) and forced swim test (FST) showed that TSA can significantly reduce the immobility time of depressed mice. Chronic administration of TSA increased p-ERK and p-CREB, BDNF proteins in mice hippocampus. We further explored the potential mechanism of TSA' antidepressant effect. TSA significantly increased the expression of p-ERK, p-CREB and BDNF proteins in dexamethasone-treated PC12 cells, and this enhancement was suppressed by pretreatment with the extracellular signal-regulated kinase (ERK) inhibitor SL327. Moreover, we observed that SL327 treatment markedly suppressed the increased levels of p-ERK, p-CREB and BDNF in mice hippocampus induced by TSA, preventing the antidepressant effects of TSA. Taken together, our results suggest that the antidepressant-like effects of TSA were mediated by ERK-CREB-BDNF pathway in mice hippocampus.