Intrahypothalamic perfusion of KP102 stimulates growth hormone release in goats

The hypothalamic actions of KP102 (also called GHRP-2) on the release of GH were studied in female goats. KP102 (10(-5) M) was perfused into the goat hypothalamus through a microdialysis probe (CMA/10 probe with a 4 mm membrane length) at a rate of 4 microl/min for 90 min, and plasma GH concentrations before and after perfusion were measured. The intrahypothalamic perfusion of 10(-5) M KP102 significantly stimulated GH release in goats (P<0.05). The GH levels began to rise after commencement of perfusion, and reached a maximum mean value at 180 min. The concentrations of GH at 165, 180, 195, 210, 225 and 240 min after commencement of perfusion of KP102 were significantly higher than the corresponding values for control animals (P<0.05). KP102 had no effect on GH pulse frequency, but it significantly increased the GH pulse amplitude after the perfusion (P<0.05). In contrast to KP102, intrahypothalamic perfusion of 10(-5) M GHRH had no effect on the stimulation of GH release in goats even if intravenous injection of 10(-5) M GHRH significantly stimulated GH release (P<0.05). These results suggest that KP102 may act partly on the hypothalamus to stimulate GH release in goats.