Effect of Testosterone on Hypothalamic LH-RH Content

Publisher Website
Google Scholar
Abstract
Hypothalamic LH-RH [luteinizing hormone-releasing hormone] content in male rats is lowered after castration. The s.c. implantation of testosterone or testosterone propionate-packed Silastic tubing (from 0.5-6 cm in length) in a range which encompassed the normal circulating plasma testosterone concentration, prevented this lowered LH-RH content 21 days following castration and simultaneous implantation. The temporal response to implanted testosterone was studied: rats were killed 1, 2, 4, 8, 14 and 21 days after castration and simultaneous implantation of 3 cm testosterone-packed Silastic tubing. Hypothalamic LH-RH content began to decrease in the castrated group after 4 days and fell progressively thereafter. The hypothalamic LH-RH content of the castrated group maintained with constant physiological levels of testosterone showed no such reduction at any time following castration. Circulating testosterone in physiological concentrations can probably maintain a normal hypothalamic LH-RH content and demonstrate an action of testosterone, in physiological concentrations, in the feedback regulation of LH-RH secretion.