Continuous subcutaneous growth hormone releasing factor analogue augments growth hormone secretion in normal male subjects with no desensitization of the somatotroph.

The effects of 8 day continuous subcutaneous (s.c.) infusions of growth hormone releasing hormone analogue (NLE27GRF(1-29)NH2 (GHRH.A)) on growth hormone (GH) secretion were studied in 14 normal adult male volunteers. GHRH.A was administered in doses which ranged from 7.5 to 120 ng/kg/min in doubling steps. Baseline GH profiles obtained during a 24 h infusion of normal saline in each subject were compared with profiles performed on days 1 and 8 of the infusion. Doses above 30 ng/kg/min augmented GH pulse amplitude and frequency. Doses of 60 ng/kg/min and 120 ng/kg/min appeared more satisfactory as these represented doses on the upwards slope of the dose response curve. However, at a dose of 120 ng/kg/min the GH secretion did not return to baseline for 12 of the 24 h. There was no evidence of desensitization or of depletion of the releasable GH pool with any dose. The possibility of treatment of short children with depot preparations of GHRH.A appears promising.