Hormone receptors and sexuality in the human female

There is only inferential evidence based on observational studies and deductive reasoning that allows us to suppose there are hormone receptors in the human brain that are associated with libido. Data indicate that sexually active pubescent women have higher testosterone levels than matched controls. However, any number of nonhormonal events in puberty could be related to these changes. Another circuitous way to look at hormone libido receptors in the brain is by evaluating patients on birth control pills, in whom sexual activity paradoxically decreases. Sex hormone-binding globulin (SHBG) levels are increased, and, therefore, free testosterone levels seem to be affected by the use of birth control pills. In addition, the progestins in the pill are 19-nortestosterone derivatives, which may have some androgenic effect in their own right. Women on estrogen replacement therapy with the addition of testosterone seem to report increased libido, and there is subjective information that there is an increase in psychological sense of well-being. It has been well documented that females with adrenogenital syndrome are masculinized in utero, indicating imprinting on behavior. Because of the nature of the end point (e.g., increased libido), it is difficult to draw concrete conclusions on the presence of libido receptors in the human brain. Because the outcomes and end points are so soft, it is difficult to come to a consensus, and in fact this topic polarizes opinions of the pure scientist (objective) against the clinician (subjective).