[Comparison with growth hormone responses to various drugs or substances in patients with active acromegaly (author's...

Growth hormone (GH) responses to L-dopa, 2-Br-alpha-ergocryptine (CB-154), thyrotropine-releasing hormone (TRH), luteinizing hormone-releasing hormone (LH-RH), glucagon and glucose were investigated in six patients with active acromegaly. The following results were obtained. 1) Subcutaneous injection of 1 mg glucagon caused a clear-cut decrease in plasma GH levels in 5 out of 6 active acromegalic patients at 30 minutes after the injection. In 2 out of 6 patients a rebound of plasma GH was observed. 2) In three out of six patients with active acromegaly, oral administration of 0.5 g L-dopa caused a significant suppression of plasma GH levels. 3) CB-154 (2.5mg) administered orally elicited a marked decrease in plasma GH levels in the same three patients who showed a significant suppressive GH reponse to L-dopa, and the inhibitory effect of CB-154 on GH secretion lasted for 6 hours. These patients who had a GH response to L-dopa or CB-154 were named "responders". 4) Intravenous administration of TRH resulted in a significant increase in plasma GH in 4 patients 3 of whom were responders and the other a non-responder. 5) Pretreatment with CB-154 did not modify the TRH-induced GH increase in all patients who had a positive response to TRH. 6) A significant increase in plasma GH was elicited by the intravenous injection of 100 mug LH-RH in 3 out of 6 patients with acromegaly. 7) When oral administration of CB-154 had been given 2 hours before LH-RH, the GH response to LH-RH was blunted in two of three patients who had a LH-RH-induced increase in plasma GH levels.