Sex drive in women

Many women taking hormones for birth control or menopause complain of losing their sex drive.

A new study examining monkey lust may help explain why so many women taking hormones for birth control or menopause complain of losing their sex drive.

According to Web Md, researchers from the Yerkes National Primate Research Center in Atlanta reported that female pigtail macaques showed far less interest in sex after being given medroxyprogesterone (MPA), a synthetic form of the hormone progesterone.

The study also showed that the monkeys were also more aggressive and anxious when taking MPA than when taking estrogen alone or a combination of estrogen and natural progesterone.

MPA is the synthetic progestin used in Prempro, the most widely prescribed hormone replacement therapy in the United States, and in the injectable form of the contraceptive Depo-Provera.

According to lead investigator Karen Pazol,"The monkey model is really appropriate for studying (hormonal influences) on sexual behavior. In most species, the ability to engage in sexual behavior is hormone modulated. In primates and humans, ability is in no way controlled by hormones, but hormones do control (sexual) motivation."

The six female macaques were treated with one-week courses of each of the following: estrogen only, estrogen plus natural progesterone, and estrogen plus MPA.

The animals exhibited normal aggression patterns while on estrogen or estrogen plus natural progesterone, but aggression levels increased when they were on the estrogen/MPA combination.