Ketamine: Insights into antidepressant effects Changes in the levels of a microRNA molecule that regulates the activity of a specific gene may be responsible for some of the antidepressant effects of the drug ketamine. Ketamine is used as a tranquilizer and anesthetic, especially in veterinary practice, but there is increasing interest in its antidepressant action in humans. Researchers in China and USA led by Xiao-Bin Wang at the Affiliated Hospital of Southwest Medical University in Luzhou, China, found that ketamine dramatically raised the levels of a specific microRNA in the prefrontal cortex region of rats’ brains. This effect was linked to the ability of the microRNA to inhibit a gene and thus decrease the production of a receptor protein in brain cell membranes. The molecular signaling pathway this research has identified could be a target for new antidepressant therapies.