This story is about testosterone, but it begins in the brain -- in the pituitary gland, which makes a hormone called LH (luteinizing hormone). In the chemical chain of events involved in the production of testosterone, the pituitary is the thermostat, a regulator that controls the testes -- the "furnace" in effect. The furnace cranks out heat -- testosterone -- which, in turn, stimulates the prostate.
The level of testosterone in the blood is constantly monitored by the brain, which regulates how much LH is needed.
Hopkins researchers recently were surprised to learn that when the prostate removed, LH goes up--and so, then, testosterone--causing
researchers to speculate that the prostate produces a substance that controls LH secretion.
The Hopkins investigators were studying the effect of radical prostatectomy these hormones in 63 men, wondering whether some change
in hormonal make-up might explain a loss of libido experienced by some men after surgery. "In normal men, the major factors that influence
sexual function are blood flow, nerve supply, and hormones," explains Urologist-in-chief Patrick C. Walsh, M.D., one of the authors of the
study. "A great deal of attention has been placed on studying what disrupts the nerve supply and blood supply during surgery -- but up to this point,
there has been little attention as what happens to the hormones." Some scientists have theorized that perhaps a surgery, there is a decrease in male
hormones, "and maybe this is why some men have a diminished libido after surgery."
The newly discovered information, that the pituitary gland makes more LH after radical prostatectomy, "suggests that the prostate is also making
an inhibitor that regulates the release of LH from the pituitary," says Walsh, "raising the fascinating hypothesis that the prostate itself may
influence hormone levels in an effort to modulate its own growth."
The increase in testosterone is not noticeable, Walsh adds, "but it certainly dispels the idea that a loss of male hormones contributes to a loss
of the sex drive." Instead, Walsh adds, a more like cause of this diminished libido after surgery is depression. In most cases, " treating the
depression restores the sex drive back to normal."
Leslie R. Miller, Alan W. Partin, Daniel W. Chan,
Debra J. Bruzek, Adrian S. Dobs, Jonathan I. Epstein,
and Patrick C. Walsh. "Influence of Radical Prostatectomy
on Serum Hormone Levels," Journal of Urology, Vol. 1160,
449-453, August 1998.