U.S. Department of Health and Human Services

Ephedrine Does Not Activate Brown Fat

A recent study has found that in humans, brown fat tissue is activated by mild cold temperature exposure, but not by the drug ephedrine, a decongestant and bronchodilator known to induce weight loss. Many scientists believe that brown adipose tissue (BAT)—a type of fat tissue known to increase energy expenditure, which in turn can promote weight loss—could serve as an ideal target for the development of treatment strategies for obesity. While mild cold temperature exposure is known to activate BAT, safe and effective pharmacological agents could offer a more practical therapeutic approach. Research scientists sought to determine whether ephedrine could induce BAT activation. Ephedrine is known to stimulate the sympathetic nervous system—the portion of the nervous system broadly responsible for the “flight or fight” response and also for the stimulation of BAT. Healthy adult volunteers were either given ephedrine injections, a “cooling vest” set to 57 degrees Fahrenheit, or saline injections as a control. The scientists found that cold exposure, but not ephedrine treatment, activated BAT tissue. In both ephedrine and cold exposure treatment conditions, energy expenditure, basal metabolic rates, and blood pressure increased. However, heart rates were raised with ephedrine treatment, but reduced with cold exposure. These results demonstrated that ephedrine does not induce weight loss through BAT activation. Further research aimed at understanding the brain and molecular pathways that activate BAT upon exposure to cold temperatures may reveal new avenues for the development of anti-obesity therapeutics.

Cypess AM, Chen Y-C, Sze C, et al. Cold but not sympathomimetics activates human brown adipose tissue in vivo. Proc Natl Acad Sci USA 109: 10001-10005, 2012.