Selective inhibition of sleep related growth hormone release by Phe-4-somatostatin

J. A. Cabranes, A. Vela, F. Timoneda, C. A. Meyers, D. H. Coy, A. V. Schally, A. L. Charro

Research output: Contribution to journalArticlepeer-review


We have compared the effects of somatostatin (SS) and the somatostatin analog Phe-4-Ss on nocturnal GH secretion in three normal male volunteers, 20 to 23 years of age. Subjects were studied in our sleep laboratory on 5 consecutive nights. Nights 1 and 2 were used for adaptation. On the third night (control night), all patients exhibited a typical GH peak accompanying slow-wave sleep, with maximum GH levels from 9.2 to 27 ng/ml. Insulin, glucagon and glucose levels were episodic and sleep-independent. On night 4, subjects received SS infusion at a rate of 3 μg/min, which inhibited GH levels consistently below 2.4 ng/ml. In two cases a post-infusion rebound of GH levels was observed. During SS infusion all three subjects showed a significant decrease in insulin levels (p < 0.0005), followed by an immediate rebound after infusion was stopped. Glucagon levels fell significantly during infusion (p < 0.001, p < 0.025 and p < 0.00025 respectively). Glucose was significantly higher than on the control night in subject No. 3 (p < 0.0005) and similar to the control night in subjects 1 and 2. On the fifth night, Phe-4-SS was infused at a rate of 0.75 μg/min. GH levels decreased significantly as compared to the control night in all three subjects and remained virtually constant throughout the night. Insulin levels were diminished in subject No. 1 (p < 0.0005), but were comparable to control values in subjects 2 and 3. Cessation of analog infusion was followed by a rebound in insulin levels in all three subjects. Glucagon values were not significantly lowered and the rebound effect was not apparent. Glucose levels were higher in response to Phe-4-SS than on the control night, and fell below infusion values (p < 0.001) after administration was discontinued. It was concluded that Phe-4-SS inhibits nocturnal secretion of GH more selectively than SS, but its effect is not more prolonged than that of SS.

Original languageEnglish (US)
Pages (from-to)421-431
Number of pages11
JournalResearch communications in chemical pathology and pharmacology
Issue number3
StatePublished - 1984
Externally publishedYes

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Toxicology
  • Pharmacology
  • Pharmacology, Toxicology and Pharmaceutics(all)


Dive into the research topics of 'Selective inhibition of sleep related growth hormone release by Phe-4-somatostatin'. Together they form a unique fingerprint.

Cite this