l-Ornithine stimulates growth hormone release in a manner dependent on the ghrelin system

Food Funct. 2017 Jun 1;8(6):2110-2114. doi: 10.1039/c7fo00309a. Epub 2017 May 17.


We found that intraduodenal administration of l-ornithine (l-Orn) stimulates growth hormone (GH) secretion in Wistar rats, and then investigated its mechanism. GH-releasing activity after intraduodenal administration of l-Orn was blocked by [d-Lys3]-GHRP-6, an antagonist of the ghrelin receptor; however, l-Orn (100 μM) has no affinity for the ghrelin receptor, suggesting that the GH-releasing activity of l-Orn is mediated via ghrelin release and activation of the ghrelin receptor. Intraduodenally administered l-Orn increased ghrelin mRNA expression in the duodenum but not in the stomach or hypothalamus. In addition, l-Orn-induced GH-releasing activity was inhibited by propranolol, an antagonist of β-adrenergic receptor, which is known to be coupled to ghrelin release. In conclusion, intraduodenally administered l-Orn stimulates GH secretion through the sympathetic nervous and ghrelin systems.

MeSH terms

  • Animals
  • Duodenum / metabolism
  • Ghrelin / metabolism*
  • Growth Hormone / metabolism*
  • Hypothalamus / metabolism
  • Male
  • Ornithine / metabolism*
  • Rats
  • Rats, Wistar
  • Receptors, Ghrelin / metabolism


  • Ghrelin
  • Receptors, Ghrelin
  • Growth Hormone
  • Ornithine