That '4 hour erection': new discovery may help prevent a complication of priapism

For men coping with painful erections lasting for long periods of time, or priapism, new research published online in The FASEB Journal (http://www.fasebj.org) offers hope. That's because researchers from the United States and China show that the enzyme adenosine deaminase may prevent priapism from progressing to penile fibrosis, a condition associated with the build up of scar tissue and eventual impotence. As penile fibrosis is a complication of priapism, so priapism is a complication of sickle cell disease. Adenosine deaminase, which breaks down adenosine, is already used in humans as a treatment for a rare immune disorder.

"Coping with priapism is hard enough, but knowing that it can ultimately lead to fibrosis within the penis adds insult to injury," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "Hopefully this discovery can yield new drugs that relieve the excitatory signals sent by adenosine so that these men to get some relief."

For the study, the researchers used two priapism animal models to determine the role of increased adenosine in penile fibrosis, a dangerous problem believed to be caused by priapism. One model was that of adenosine deaminase-deficient mice and the other was sickle cell disease transgenic mice. Both of these sets of mutant mice were treated with the enzyme adenosine deaminase enzymes to lower adenosine levels. After 8 weeks, they found that this enzyme significantly lowered adenosine levels in the penises of both groups of test mice. Reduction of adenosine by these enzymes successfully prevented and corrected penile fibrosis in both sets of mice.

"Because of our study, we have revealed that increased adenosine signaling contributes to the pathogenesis of the progression of priapism to penile fibrosis," said Yang Xia, a scientist involved in the study from the University of Texas-Houston Medical School's Department of Biochemistry and Molecular Biology. "This finding led to a novel therapeutic possibility to treat and prevent this dangerous complication seen in priapic humans by targeting on this signaling pathway in the near future."

Receive monthly highlights from The FASEB Journal by e-mail. Sign up at http://www.faseb.org/fasebjournalreaders.htm. The FASEB Journal (http://www.fasebj.org) is published by the Federation of the American Societies for Experimental Biology (FASEB). The journal has been recognized by the Special Libraries Association as one of the top 100 most influential biomedical journals of the past century and is the most cited biology journal worldwide according to the Institute for Scientific Information. FASEB comprises 22 nonprofit societies with more than 80,000 members, making it the largest coalition of biomedical research associations in the United States. FASEB advances health and welfare by promoting progress and education in biological and biomedical sciences through service to its member societies and collaborative advocacy.

Details: Jiaming Wen, Xianzhen Jiang, Yingbo Dai, Yujin Zhang, Yuxin Tang, Hong Sun, Tiejuan Mi, Prasad V. Phatarpekar, Rodney E. Kellems, Michael R. Blackburn, and Yang Xia. Increased adenosine contributes to penile fibrosis, a dangerous feature of priapism, via A2B adenosine receptor signaling. FASEB J. doi:10.1096/fj.09-144147 http://www.fasebj.org/cgi/content/abstract/fj.09-144147v1

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October 26, 2009