Effect of long-term administration of an analog of growth hormone-releasing factor on the GH response in rats

Tsuyoshi Karashima, Donald Olsen, Andrew V. Schally

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The effect of the repeated or continuous administration of an analog of GH releasing factor (GH-RF), D-Tyr-1, D-Ala-2, Nle-27, GH-RF (1-29)-NH2 (DBO-29), on the subsequent response to this peptide was investigated in pentobarbital-anesthetized male rats. A sc administration of this analog induced a greater and more prolonged GH release than doses 10 times larger of GH-RF(1-29). The GH increase after sc injection of 10 μg/kg bw of the analog was greater than that induced by iv administration of 2 μg/kg bw of GH-RF(1-44). Pretreatment with 10 μg/kg bw of the analog did not affect the pituitary response to a strong stimulus (20 μg/kg bw) of GH-RF(1-44), 24 h later. Pretreatment with the analog in doses of 10 μg/kg bw, sc twice a day, 5 days per week for 4 weeks, significantly diminished the GH release in response to a sc injection of the analog (10 μg/kg bw), as compared to vehicle-pretreated controls (P <0.01). On the other hand, a continuous sc administration of 0.4 μg/h of the analog to intact rats for 7 days did not result in a decrease in GH response to a sc injection of the analog (10 μg/kg bw). Since the rats injected repeatedly with the analog for 4 weeks still showed a marked, although somewhat reduced response, analogs of this type may be useful clinically.

Original languageEnglish (US)
Pages (from-to)2437-2444
Number of pages8
JournalLife Sciences
Volume40
Issue number25
DOIs
StatePublished - Jun 22 1987
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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