Influence of Gonadal Function on GH Secretion

In contrast to the relatively clear-cut sexually dimorphic secretory pattern in rodents, episodic growth hormone (GH) secretion in humans is unpredictable, with the exception of the first cycle of slow-wave sleep, thus making their clinical assessment particularly difficult. Nevertheless, it has been reported that spontaneous GH secretion is increased around puberty in both male and female subjects, thus suggesting a facilitative role of gonadal steroids (1,2). Increased serum testosterone levels during normal puberty in boys is associated with increased GH secretory burst mass and amplitude (3). Similarly, testosterone replacement in hypogonadal boys increased the number of GH pulses and their amplitude (4). Finally, in normal aging there is an association between reduction of spontaneous GH secretion and decreased andro- genic activity (5). Taken together these findings suggest that androgens play a facilitative role in spontaneous GH secretion in humans.