AI Article Synopsis
- Intraduodenal administration of l-ornithine (l-Orn) enhances growth hormone (GH) secretion in Wistar rats through a specific mechanism.
- The GH release triggered by l-Orn is blocked by the ghrelin receptor antagonist [d-Lys]-GHRP-6, indicating that l-Orn's effects are mediated by ghrelin release rather than direct binding to the receptor.
- Additionally, the study shows that l-Orn increases ghrelin mRNA levels in the duodenum and that its GH-releasing activity is inhibited by propranolol, connecting the sympathetic nervous system and ghrelin pathways in this process.
Article Abstract
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-Lys]-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.
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| http://dx.doi.org/10.1039/c7fo00309a | DOI Listing |
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