17 January 2013
Viagra's surprising weight-loss properties
by Will Parker
German scientists investigating why mice given Viagra were resistant to obesity say they have discovered a "quite amazing" anti-obesity effect related to a cell signaling pathway that tells the body how to store fat.
The researchers say that sildenafil (the active ingredient in Viagra) converts white fat cells into brown fat, which burns caloric energy much more effectively. The results of the study appear in The Journal of the Federation of American Societies for Experimental Biology.
One of the authors of the new study, Dr. Alexander Pfeifer, Director of the Institute for Pharmacology and Toxicology at the University of Bonn, explained that sildenafil works as an erectile dysfunction drug by preventing the degradation of cyclic guanosine mono-phosphate (cGMP). Nitric oxide in the tissue of the penis binds to guanylate cyclase receptors, which results in increased levels of cGMP, leading to vasodilation and increased inflow of blood into the spongy tissue of the penis, causing an erection.
Pfeifer's team of researchers decided to investigate sildenafil's effects on fat tissue after past experiments with treated mice revealed that they were resistant to obesity - even when fed with high-fat diet. "We have been researching the effect of cGMP on fat cells for quite some time now," said Pfeifer. "This is why sildenafil was a potentially interesting candidate for us."
The research team, from the University of Bonn, the German Federal Institute for Drugs and Medical Devices and the Max Planck Institute for Heart and Lung Research, administered the potency drug to rodents for seven days. "The effects were quite amazing," said Dr. Ana Kilic, one of Pfeifer's team. "Sildenafil increased the conversion of white fat cells, which are found in human 'problem areas,' into beige [brown] ones. Beige fat cells burn the energy from ingested food and convert it to heat."
"Sildenafil is not only able to minimize erectile problems, but it can also reduce the risks of gaining excessive weight," Pfeifer added. "In addition, it might be possible to decrease complications related with obesity, but this will need to be proven in additional studies."
But Pfeifer cautions lovers with love handles who want to immediately use sildenafil as a weight loss drug. "We are currently in the basic research stage, and all the studies have been exclusively performed on mice," he stresses.
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Source: University of Bonn