Development of new antidepressants from pyrethroid insecticide deltamethrin.

In this study, we investigated the antidepressant-like effect of type II pyrethroid deltamethrin (DM) in mice. The effects of DM were assessed using the forced swimming test (FST) and were compared with those of type I pyrethroid permethrin (PM). Intraperitoneal administration of DM (5 and 10mg/kg) increased the expression of BDNF mRNA in the hippocampus. DM significantly decreased the immobility time in the FST, and did not affect locomotor activity and motor coordination, suggesting that DM has an antidepressant-like effect. This effect of DM was inhibited by intracerebroventricular injection of K252a, which is an inhibitor of the BDNF receptor TrkB, indicating that the antidepressant-like effects of DM are mediated by BDNF/TrkB signaling pathways. The results of the present study suggest that DM possesses antidepressant-like properties, and may be a possible source for the development of drugs to treat neurodegenerative and psychiatric disorders including depression.