Author Interviews, Depression, Endocrinology, Testosterone / 09.04.2015
Testosterone May Protect Against Mood-Related Disorders
MedicalResearch.com Interview with:
Mohamed Kabbaj, PHD
Professor of Biomedical Sciences & Neurosciences
College of Medicine
Florida State University
Medical Research: What is the background for this study? What are the main findings?
Dr. Kabbaj: While anxiety and depressive disorders a major public health concern worldwide, so too are the pervasive sex differences that exist within these pathologies. Fluctuations in the predominant female reproductive hormones, estradiol and progesterone, are thought to be a major contributor to the higher prevalence of anxiety and depression in women compared to men. However, many studies in humans and rodents alike have demonstrated that testosterone, the primary male sex hormone, also influences affective status and may yield protective benefits against the development of mood-related disturbances. Indeed, hypogonadal males with low testosterone levels experience increased rates of anxiety and depressive symptoms. In many of these cases, testosterone replacement alone or in addition to antidepressant medication have been shown to effectively improve mood. How this hormone acts in the brain to exert its beneficial effects, however, is much less clear. Interestingly, it is well-known that many of testosterone’s effects in the brain occur via its conversion to estrogen by the enzyme aromatase. What remained unclear was whether or not this conversion to estrogen was critical for testosterone’s protective anxiolytic and antidepressant effects—so Nicole Carrier and Samantha Saland from Dr. Kabbaj’s lab aimed to figure out just that.
To do this, Carrier and Saland targeted an area of the hippocampus in the brain involved in mood regulation where testosterone is known to act to carry out some of its anxiolytic and antidepressant effects in male rats. Here, they inhibited the enzyme responsible for the conversion of testosterone into estrogen and investigated performance in mood-related behaviors. In doing so, they discovered that testosterone’s anxiolytic- and antidepressant-like effects were lost unless this hormone was first converted into estrogen. Importantly, they also found that continuous testosterone and estrogen treatments had very similar effects on the expression of genes within this brain region that are highly implicated in the regulation of mood as well as antidepressant treatments.
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