Investigators at Howard University have recently observed the antidepressant effect of nicotine in Wistar-Kyoto (WKY) rats, a putative behavioral model of depression. Drs. Youssef Tizabi and K. Y. Tyler will present their findings at the Experimental Biology 2002 meeting in New Orleans on April 22.
When compared to the general population, individuals with a history of clinical depression are more likely to smoke cigarettes. In addition, depressed patients often encounter difficulty in their smoking cessation efforts, which may partially be attributed to relapsed depressive episodes during withdrawal. Although cigarette smoke contains over 3,000 chemicals, nicotine is the primary constituent that acts on the brain. As a result, scientists have suggested that cigarette smoking may be an attempt by depressed individuals to self-medicate with nicotine.
Depression is a major mental health disorder that is estimated to affect nearly 10 million American adults each year. Treatment of depressive illness, which includes various antidepressant medications and psychotherapy, is effective in 60-80 percent of patients. Despite the relative success of current antidepressant therapies, the precise cause of depression remains unclear. Animal models of depression, such as the WKY rat, are important research tools that can be used to screen potential antidepressant drugs and to study the underlying brain mechanisms involved in depression. These recent findings suggest that nicotine or nicotinic agonists (nicotine-like agents) may have therapeutic potential for the treatment of depressive illnesses. However, researchers insist that the risks associated with cigarette smoking outweigh any potential therapeutic benefits of nicotine contained in this form.
Presently, the neurochemical mechanisms by which nicotine produces this antidepressant effect in the WKY rat are being investigated. Researchers will attempt to correlate these recent behavioral findings with chemical changes in the brain. The investigators hope to forge a clearer understanding of nicotine's impact on the depressed brain, which may eventually provide new therapeutic targets for the treatment of depressive illnesses.