Age-dependent changes in the reproductive axis responsiveness to kisspeptin-10 administration in healthy men.

The present study was designed to assess the responsiveness of hypothalamic-pituitary-gonadal axis to kisspeptin administration with increasing age in men. Human kisspeptin-10 was administered in single iv bolus dose (1 µg/kg BW) to healthy adult, middle and advanced age men. Serial blood samples were collected for 30 min pre- and 120 min post-kisspeptin injection periods at 30-min interval. Analysis of plasma LH by ELISA showed a significant (p < 0.05) increase after kisspeptin-10 administration in all groups, whereas plasma testosterone concentration was significantly elevated (p < 0.05) after kisspeptin-10 injection only in the adult men group. Present results suggest that in men, central hypothalamic-pituitary axis remains active and shows responsiveness to kisspeptin stimulation across life. However, Leydig cell responsiveness to kisspeptin-induced LH decreases with age in men.