Comparative study on the responses of plasma GH to synthetic GH-releasing factor and other stimulatory and inhibitory agents in patients with acromegaly.

Ten patients with active acromegaly received synthetic human pancreatic GH releasing factor (hpGHRF-44), and the GH responses to GHRF were compared with the basal GH levels and with the GH responses to arginine, TRH, LH-RH, somatostatin, and L-dopa. There were no significant relationships between the plasma GH responses to GHRF and the results of the stimulatory and inhibitory tests mentioned above, except that the responses to GHRF showed weak positive or negative correlations with the responses to LH-RH (r = +0.56) or with the basal GH levels (r = -0.57). These results indicate that acromegalic somatotrophs would have GHRF receptors as well as several other receptors to hypothalamic hormones and to dopamine, and that there might be no distinct relationship between the somatotroph sensitivities to GHRF and to other stimulatory or inhibitory stimuli. Further studies are required regarding the weak correlations between the response to GHRF and that to LH-RH or basal GH value.