Beneficial effects of growth hormone-releasing hormone agonists on rat INS-1 cells and on streptozotocin-induced NOD/SCID mice

Xianyang Zhang, Tengjiao Cui, Jinlin He, Haibo Wang, Renzhi Cai, Petra Popovics, Irving Vidaurre, Wei Sha, Janine Schmid, Barbara Ludwig, Norman L Block, Stefan R. Bornstein, Andrew V Schally

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Agonists of growth hormone-releasing hormone (GHRH) have been previously reported to promote growth, function, and engraftment of islet cells following transplantation. Here we evaluated recently synthesized GHRH agonists on the proliferation and biological functions of rat pancreatic β-cell line (INS-1) and islets. In vitro treatment of INS-1 cells with GHRH agonists increased cell proliferation, the expression of cellular insulin, insulin-like growth factor-1 (IGF1), and GHRH receptor, and also stimulated insulin secretion in response to glucose challenge. Exposure of INS-1 cells to GHRH agonists, MR-356 and MR-409, induced activation of ERK and AKT pathways. Agonist MR-409 also significantly increased the levels of cellular cAMP and the phosphorylation of cAMP response element binding protein (CREB) in INS-1 cells. Treatment of rat islets with agonist, MR-409 significantly increased cell proliferation, islet size, and the expression of insulin. In vivo daily s.c. administration of 10 μg MR-409 for 3 wk dramatically reduced the severity of streptozotocin (STZ)-induced diabetes in nonobese diabetic severe combined immunodeficiency (NOD/SCID) mice. The maximal therapeutic benefits with respect to the efficiency of engraftment, ability to reach normoglycemia, gain in body weight, response to high glucose challenge, and induction of higher levels of serum insulin and IGF1 were observed when diabetic mice were transplanted with rat islets preconditioned with GHRH agonist, MR-409, and received additional treatment with MR-409 posttransplantation. This study provides an improved approach to the therapeutic use of GHRH agonists in the treatment of diabetes mellitus.

Original languageEnglish (US)
Pages (from-to)13651-13656
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number44
DOIs
StatePublished - Nov 3 2015

Keywords

  • Diabetes
  • Ghrh agonists
  • INS-1
  • Signaling pathways
  • Transplantation

ASJC Scopus subject areas

  • General

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