July 12 (UPI) -- Smell receptors found throughout the body could help diagnose and treat diseases, including cancer, according to a new review of studies.
Researchers from the Ruhr-University Bochum in Germany, after examining more than 200 studies, determined that olfactory receptors -- proteins that bind to odors aiding in the sense of smell -- perform many unknown functions outside the nose. Their findings were published in the July issue of Physiological Reviews.
Originally, these receptors were thought to be only in the sensory nerve cells of nasal cavity tissues.
But the researchers report that these receptors "occur in nearly the entire human body, and they appear to be substantially more functionally important than previously suggested." This includes the testis, lung, intestine, skin, heart and blood.
"Several essential physiological and pathophysiological processes have been described as targeted by human olfactory receptors, including path finding, cell growth, cell death, differentiation and apoptosis, migration and secretion," they said.
The researchers found the receptors may play a role in regulation of heart function, death of leukemia cells, reduction of the spread of liver cancer cells and increased regeneration of skin cells to speed wound healing.
The researchers also learned that these receptors affect the development of diseases, including in the prostate, colon and digestive tract.
Though they play a role in disease progression and organ function, the researchers said the process is not fully understood.
"Although the sense of smell is not essential for human survival, its loss can indicate various neurodegenerative processes and significantly influence an affected person's quality of life," the researchers wrote. "This may also serve as a starting point for future studies trying to understand the underlying pathologies. However, several ORs appear to be highly conserved among mammals and underlie stronger evolutionary constraints than OR genes expressed exclusively in the OE [nose]."