A review of more than 200 studies reveals that olfactory receptors--proteins that bind to odors that aid the sense of smell--perform a wide range of mostly unknown functions outside the nose. The function of extra-nasal olfactory receptors has the potential to be used in the diagnosis and treatment of health conditions such as cancer. The article is published in the July issue of Physiological Reviews.

Olfactory, or smell, receptors were originally thought to be only in the sensory nerve cells (neurons) of nasal cavity tissues. However, more recent and extensive study suggests that the receptors "occur in nearly the entire human body, [and] they appear to be substantially more functionally important than previously suggested," researchers from Ruhr-University Bochum in Germany wrote. In addition to the receptors playing a major role in the sense of smell, "several essential physiological and pathophysiological processes have been described as targeted by human [olfactory receptors], including path finding, cell growth, [cell death], migration and secretion."

The research team summarized the location and purpose of certain types of olfactory receptors, including those that may be beneficial to general health:

• Receptors present in heart muscle cells may be a metabolic regulator of heart function.
• Receptors activated in the immune system have been seen to promote the death of certain types of leukemia cells.
• Smell receptors in the liver reduce the spread of liver cancer cells.
• Receptors in the skin increase the regeneration of skin cells and help speed wound healing.

Many cancer patients suffer from a loss of body mass known as cachexia. Approximately 20 percent of cancer related deaths are attributed to the syndrome of cachexia, which in cancer patients is often characterized by a rapid or severe loss of fat and skeletal muscle. Dr. Melinda Sheffield-Moore, professor and head of the Department of Health and Kinesiology, along with researchers at University of Texas Medical Branch, recently published research in the Journal of Cachexia, Sarcopenia and Muscle showing that the hormone testosterone is effective at combatting cachexia in cancer patients and improving quality of life.

These findings are important, as there are currently no established therapies targeting this loss of skeletal muscle, and without an intervention, patients lose muscle function and become fatigued and weakened.
"We hoped to demonstrate these patients would go from not feeling well enough to even get out of bed to at least being able to have some basic quality of life that allows them to take care of themselves and receive therapy," Dr. Sheffield-Moore said.

Dr. Sheffield-Moore said doctors sought her expertise in nutrition and metabolism when patients were losing tremendous amounts of weight from cancer cachexia. She said that previous nutrition-focused treatment failed to combat this severe loss of body mass, which led her team to investigate the hormone testosterone as an option to combat the often debilitating consequences of cancer cachexia.
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"We already know that testosterone builds skeletal muscle in healthy individuals, so we tried using it in a population at a high risk of muscle loss, so these patients could maintain their strength and performance status to be able to receive standard cancer therapies." Dr. Sheffield-Moore said.