Researchers from the University of Bonn have treated mice with Viagra and discovered that the drug converts white fat cells (those unwanted denizens of the belly and similar swollen regions) into beige fat cells. Instead of storing excess energy, these recently discovered beige fat cells burn the energy from ingested food and convert it to heat. Viagra also appears (at least in mice) to decrease the risk of other complications caused by obesity.
Viagra (also known as sildenafil) is used to treat erectile dysfunction, pulmonary arterial hypertension, and altitude sickness. It increases levels of the intracellular messenger cyclic guanosine mono-phosphate (cGMP), which produces smooth muscle relaxation and thereby ensuring the blood supply for an erection.
Another effect of Viagra was noticed in a 2007 study. Mice dosed with Viagra for a 12 week period did not become fat when placed on a high-fat diet. The reason for the unexpectedly small gain of weight was not known at the time.
Following on from these earlier studies, Prof. Dr. Alexander Pfeifer, Director of the Institute for Pharmacology and Toxicology at the University of Bonn, and his colleagues studied the effect of Viagra on fat cells in mice. After giving the subjects the drug for seven days at about ten times the maximum approved dosage for human use, they discovered that a significant number of the white fat cells in the mice had been converted into the far healthier beige fat cells.
The study also establishes that larger levels of cGMP prevent the remaining white fat cells from hypertrophy. When white fat cells store more energy, they become fatter rather than dividing into a larger set of cells. At least, they do this until they reach about four times their normal size, at which point they eventually divide.
Before this division happens, hypertrophy of the white fat cells causes them to release cytokines, which are immunomodulators – that is, they change the immune status of the body. In this case, they ramp up the action of the immune system, leading to chronic inflammation, which is at the base of most chronic health conditions, including cardiovascular disease, diabetes, arthritis, and even cancer. The white fat cytokines are particularly damaging to heart tissues.
The overall summary of the findings is that, at least in mice, Viagra can convert fat into calorie-burning beige fat, prevent white fat cells from overgrowing their bounds, and reduce the inflammatory response of the fat cells while reducing the amount of inflammatory cytokine messengers that are at least partly responsible for much of the chronic disease being fought by our medical systems. "It seems that sildenafil prevented the fat cells in these mice from getting onto that slippery slope," says Prof. Pfeifer.
As always in medical studies, mice are not humans, and taking severe overdoses of Viagra to change the operation of your immune system, aside from being extremely expensive, is probably not an ideal course of action at this point. "We are currently in the basic research stage, and all the studies have been exclusively performed on mice," stresses Prof. Pfeifer.
It may be some time before potentially suitable drugs for decreasing white fat cells in humans will be found, but perhaps this will eventually give users of Viagra another reason to be happy.
Source: University of Bonn
