Morphine shot affects testosterone levels

SIENA, Italy, Nov. 6 (UPI) -- Researchers in Italy, in a study using male rats, found one injection of morphine to fight persistent pain reduced the testosterone in the brain and plasma.

Study leader Dr. Anna Maria Aloisi of the University of Siena and colleagues showed opioids had "long lasting genomic effects in body areas which contribute to strong central and peripheral testosterone levels" including the brain, the liver and the testis.

"Our lab became interested in gonadal hormones several years ago when it became clear that there were many differences in pain syndromes between the sexes," Aloisi says in a statement. "In looking at differences, it was immediately apparent that these changes were introduced by different treatments, opioids in particular."

The use of opioids puts a physiological block on the reproductive system and can induce a long-lasting absence of these essential hormones from the blood and the brain, Aloisi says.

A lack of the male hormone can result in health complications including chronic fatigue, loss of stamina, emotional and sexual disturbances, as well painful skeletal and muscular complications, the researchers say.

"Until a few years ago this condition was completely unrecognized by physicians although some reports clearly showed it in many kinds of patients," Aloisi notes. "Today there remains some ignorance on this condition but gonadal hormones are more commonly cited as responsible for many chronic degenerative pathologies."

The findings are published in Molecular Pain.