Insulin-like effects on liver Golgi membrane preparations of bis(oxalato)oxovanadate(IV) complex ion, a new vanadate
A M Kordowiak1, R Trzos, R Grybos
1Department of Animal Biochemistry, Jagiellonian University, Kraków, Poland.
Abstract:
Recent studies have shown the insulin-like effect of vanadyl sulphate or sodium ortho (or meta-)vanadate administered orally to rats. Toxicity of these drugs and reluctance by the animals to drink the solutions and take food, concerning the amelioration of some diabetes syndrome discussed in 1994 by Domingo et al. (1), McNeill et al. (2) and Wiliams and Malabu (3), prompted us to investigate a new vanadate complex: disodium bis(oxalato)oxovanadate (IV), Na2[VO(OX)2]H2O. The main object of the experiment was to study whether this complex administered as 3 mmol/l solution in 0.5% NaCl during 7 days could act on the subcellular level and influence the activity of liver Golgi membrane galactosyltransferase activity. Free blood sugar level was lowered (but was still higher than in the control group) in diabetic rats after seven days of vanadate action and was accompanied by lowered, however not statistically significant, serum triglyceride levels. The yields of isolated Golgi-rich membrane fractions were about half of the level in diabetic groups (untreated and treated with vanadium) compared with the control groups. Purity of these membrane fractions, expressed as nmol Gal transferred per mg of proteins and per h, was the same in four groups investigated and showed the possibility to compare them. Activity of galactosyltransferase calculated in nmol Gal transferred per 1 g of liver and per 1 h or per whole liver in the same time (as a possibility of glycosylation of the secretory and membrane glycoproteins) was lower in both diabetic groups. However, after vanadium treatment (D+V group), the activity was higher than in untreated diabetic rats (D group) in three of five investigated animals. Vanadyl-oxalate complex did not normalize in a statistically significant manner the enzyme activity which was significantly lower in diabetes than in control. This is similar to insulin influence on the galactosyltransferase activity reported previously by Kaczmarski et al. in 1981 (4) and Kordowiak et al. in 1981 (5).
Insights
A novel vanadate complex, disodium bis(oxalato)oxovanadate (IV), showed potential in lowering blood sugar and influencing liver enzyme activity in diabetic rats. While not fully normalizing galactosyltransferase activity, it improved upon untreated diabetic conditions.
Area of Science:
- Biochemistry
- Pharmacology
- Cell Biology
Background:
- Vanadyl sulphate and sodium vanadates exhibit insulin-like effects but have toxicity and palatability issues.
- Previous research by Domingo et al., McNeill et al., and Wiliams and Malabu (1994) discussed diabetes syndrome amelioration.
- Investigating new vanadate complexes is crucial to overcome limitations of existing treatments.
Purpose of the Study:
- To evaluate the subcellular effects of a new vanadate complex, disodium bis(oxalato)oxovanadate (IV), Na2[VO(OX)2]H2O.
- To determine its influence on liver Golgi membrane galactosyltransferase activity in diabetic rats.
- To assess its efficacy in managing diabetes-related metabolic changes.
Main Methods:
- Diabetic rats were treated with a 3 mmol/l solution of disodium bis(oxalato)oxovanadate (IV) in 0.5% NaCl for 7 days.
- Liver Golgi-rich membrane fractions were isolated to assess purity and enzyme activity.
- Galactosyltransferase activity was measured in terms of nmol Gal transferred per gram of liver per hour.
Main Results:
- A reduction in free blood sugar levels was observed in treated diabetic rats, though levels remained elevated compared to controls.
- Serum triglyceride levels showed a non-statistically significant decrease after vanadate treatment.
- While galactosyltransferase activity was lower in diabetic rats, the vanadyl-oxalate complex treatment showed a trend towards improvement compared to untreated diabetic rats.
- The complex did not statistically normalize the significantly reduced enzyme activity observed in diabetes.
Conclusions:
- Disodium bis(oxalato)oxovanadate (IV) exhibits a potential insulin-like effect in diabetic rats, impacting blood sugar and liver enzyme activity.
- The vanadate complex did not fully normalize galactosyltransferase activity, similar to insulin's previously reported effects.
- Further research is warranted to explore the therapeutic potential and optimize the dosage of this vanadate complex for diabetes management.
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