Diabetes, Vol 39, Issue 7 821-827, Copyright © 1990 by American Diabetes Association

ARTICLES

Insulinlike effects of vanadate on hepatic glycogen metabolism in nondiabetic and streptozocin-induced diabetic rats

S Pugazhenthi and RL Khandelwal
Department of Biochemistry, University of Saskatchewan, Saskatoon, Canada.

The effect of oral administration of sodium orthovanadate for 5 wk on hepatic glycogen metabolism was studied in control and streptozocin-induced diabetic rats. Diabetes caused hyperglycemia (5-fold increase), hypoinsulinemia (85% decrease), and hyperglucagonemia (4-fold increase). There were also marked decreases in liver glycogen and activities of glycogen-metabolizing enzymes in liver. Although vanadate administration in control animals showed no significant effect on the various parameters measured except for a 70% decrease in plasma insulin, this treatment in diabetic rats restored these parameters to near control values. In diabetic rats, glycogen synthase a and the activity ratio (activity of glycogen synthase a divided by activity of total glycogen synthase) decreased to 30% of control levels and were restored to approximately 70-80% of control values after vanadate administration. A similar pattern was observed for the activity of synthase phosphatase. The activities of glycogenolytic enzymes, i.e., phosphorylase (activity of phosphorylase a and activity of total phosphorylase), phosphorylase kinase, and protein kinase (in presence or absence of cAMP), were significantly decreased by 40-70% in diabetic rats. These enzyme activities were recovered to 70-100% of control values after vanadate treatment. Phosphorylase phosphatase was not altered by diabetes, but the vanadate treatment of both groups, i.e., control and diabetic rats, showed a 25% increase in its activity (P less than 0.01). In conclusion, these results show insulinlike in vivo action of vanadate on various parameters related to hepatic glycogen metabolism.
CiteULike    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				L. Marzban, R. Rahimian, R. W. Brownsey, and J. H. McNeill Mechanisms by which Bis(Maltolato)Oxovanadium(IV) Normalizes Phosphoenolpyruvate Carboxykinase and Glucose-6-Phosphatase Expression in Streptozotocin-Diabetic Rats in Vivo Endocrinology, December 1, 2002; 143(12): 4636 - 4645. [Abstract] [Full Text] [PDF]

				V. Natarajan, W. M. Scribner, A. J. Morris, S. Roy, S. Vepa, J. Yang, R. Wadgaonkar, S. P. M. Reddy, J. G. N. Garcia, and N. L. Parinandi Role of p38 MAP kinase in diperoxovanadate-induced phospholipase D activation in endothelial cells Am J Physiol Lung Cell Mol Physiol, August 1, 2001; 281(2): L435 - L449. [Abstract] [Full Text] [PDF]

				S. Verma, M. C. Cam, and J. H. McNeill Nutritional Factors that Can Favorably Influence the Glucose/Insulin System: Vanadium J. Am. Coll. Nutr., February 1, 1998; 17(1): 11 - 18. [Abstract] [Full Text] [PDF]

				P. V. Rao, S. Pugazhenthi, and R. L. Khandelwal The Effects of Streptozotocin-induced Diabetes and Insulin Supplementation on Expression of the Glycogen Phosphorylase Gene in Rat Liver J. Biol. Chem., October 20, 1995; 270(42): 24955 - 24960. [Abstract] [Full Text] [PDF]

				D. E. Baker and R. K. Campbell Vitamin and Mineral Supplementation in Patients with Diabetes Mellitus The Diabetes Educator, January 1, 1992; 18(5): 420 - 427. [PDF]