Arginine-rich Coconut Kernel Diet Influences Nitric Oxide Synthase Activity in Alloxandiabetic Rats

J Sci Food Agric. 2012 Jul;92(9):1903-8. doi: 10.1002/jsfa.5558. Epub 2012 Jan 9.


Background: Coconut kernel protein (CKP) has been reported to contain significant amounts of L-arginine. Its potential effect on glucose homeostasis, possibly through the nitric oxide synthase (NO) pathway, was therefore investigated in alloxan-induced diabetic rats. Diabetes was induced by a single intraperitoneal dose of alloxan (150 mg kg⁻¹ body weight). Experimental rats were grouped as follows: Group I, normal control; Group II, diabetic control; Group III, diabetic + CKP; Group IV, diabetic + L-arginine; Group V, diabetic + L-arginine + L-N(G)-Nitroarginine methyl ester (L-NAME). Purified CKP isolated from dried coconut kernel and L-arginine was administered to rats along with a semi-synthetic diet for 45 days. L-NAME (0.5 mg kg⁻¹ body weight) was given to Group V animals. After the experimental period, serum glucose, insulin, activities of liver nitric oxide synthase and arginase, liver glycogen levels and histopathology of the pancreas were evaluated.

Results: Serum glucose, insulin and antioxidant enzyme activities and liver glycogen levels were found to be restored to basal levels in CKP-fed rats. Decreased arginase and increased nitric oxide synthase (NOS) activities were found in CKP- and arginine-fed rats. L-NAME treatment showed a partial effect on these parameters. Histopathology revealed that CKP and L-arginine feeding reduced the diabetes-related pancreatic damage in treated rats compared to the diabetic control.

Conclusion: The results observed in this study indicate that the potential antidiabetic activity of CKP may be through an arginine-NO pathway leading to pancreatic beta cell regeneration.

MeSH terms

  • Animals
  • Antioxidants / metabolism
  • Antioxidants / pharmacology
  • Antioxidants / therapeutic use
  • Arginase / metabolism
  • Arginine / pharmacology
  • Arginine / therapeutic use*
  • Blood Glucose / metabolism
  • Cocos / chemistry*
  • Diabetes Mellitus, Experimental / drug therapy*
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetes Mellitus, Experimental / pathology
  • Diet*
  • Dietary Proteins / pharmacology
  • Dietary Proteins / therapeutic use*
  • Glycogen / metabolism
  • Insulin / blood
  • Liver / drug effects
  • Liver / metabolism
  • Liver / pathology
  • Male
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Nitric Oxide Synthase / metabolism*
  • Pancreas / drug effects
  • Pancreas / pathology
  • Phytotherapy*
  • Plant Preparations / pharmacology
  • Plant Preparations / therapeutic use
  • Plant Proteins / pharmacology
  • Plant Proteins / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Seeds / chemistry
  • Signal Transduction


  • Antioxidants
  • Blood Glucose
  • Dietary Proteins
  • Insulin
  • Plant Preparations
  • Plant Proteins
  • Glycogen
  • Arginine
  • Nitric Oxide Synthase
  • Arginase
  • NG-Nitroarginine Methyl Ester