Antihyperglycemic activity of L-norvaline and L-arginine in high-fat diet and streptozotocin-treated male rats

Hayarpi Javrushyan, Edita Nadiryan, Anna Grigoryan, Nikolay Avtandilyan, Alina Maloyan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Background: A decrease in nitric oxide (NO) bioavailability has been shown to cause hyperglycemia, type II diabetes mellitus (DM), and chronic cardio-metabolic complications. In turn, hyperglycemia and hypercholesterolemia are associated with increased oxidative stress that leads to reduced nitric oxide bioavailability through disruption of L-arginine transport into cells, inactivation of nitric oxide synthase, and activation of arginase. Upregulation of arginase has been demonstrated in both diabetic patients and animal models of hyperglycemia and type 2 diabetes. L-norvaline is a nonselective inhibitor of arginase that increases NO production and promotes the normal functioning of the vascular endothelium. Another means of increasing NO bioavailability in the cardiovascular system is L-arginine supplementation. Whether L-norvaline and L-arginine have antihyperglycemic effects has not been studied. Hypothesis: We hypothesized that inhibition of arginase will provide an antihyperglycemic effect and, as a result of the recovery of NO bioavailability, will protect against oxidative stress and hypercholesterolemia. Methods: Rats were fed a high-fat diet (HFD) for three weeks concomitant with the two-time injection of 30 mg/kg of streptozotocin (STZ) to induce stable hyperglycemia. We studied the antihyperglycemic properties of arginase inhibition (via L-norvaline) and its combination with NOS substrate supplementation (via L-arginine). Results: Treatment of HFD/STZ mice with L-norvaline and L-arginine reduced fasting blood glucose levels by 27.1% vs. untreated HFD/STZ rats (p < 0.001). Blood levels of total cholesterol, low-density lipoprotein (LDL), and malondialdehyde (MDA), a marker for oxidative stress, were significantly decreased in both L-norvaline- and L-norvaline+L-arginine-treated HFD/STZ rats when compared with untreated rats. In addition, administration of L-norvaline and L-arginine reversed the progression of pancreatic and kidney pathology in HFD/STZ rats as assessed by histology (p < 0.001). Conclusions: Both L-norvaline and L-arginine act as potent antihyperglycemic agents and can represent alternative therapeutic tools in individuals with hyperglycemia and pre-diabetes.

Original languageEnglish (US)
Article number104763
JournalExperimental and Molecular Pathology
Volume126
DOIs
StatePublished - Jun 2022

Keywords

  • Arginase
  • Dyslipidemia
  • High fat diet
  • Hyperglycemia
  • L-norvaline
  • Nitric oxide
  • Pre-diabetes
  • Streptozotocin

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Molecular Biology
  • Clinical Biochemistry

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