Comparative study on the preventing effects of oral vanadyl sulfate and dietary restriction on the age-related glucose intolerance in rats.
OBJECTIVE
Aging is associated with a progressive impairment of glucose tolerance. The aim of this study was to explore the protective effects of the chronic oral administration of the insulino-mimetic agent vanadyl sulfate (VOSO4) as compared with those exerted by a long-lasting dietary restriction.


METHODS
Male Sprague-Dawley rats, either fed ad libitum (AL) or subjected to 40% dietary restriction (DR), were used. VOSO4 (0.5 mg/mL drinking water) was administered to a subgroup of AL rats for two months, starting at 16 months of age. Rats were subjected to an intravenous glucose tolerance test (IVGTT) at 16 and 18 months of age. Finally, the beta-cell responsiveness to glucose was evaluated in vitro by the isolated perfused pancreas preparation.


RESULTS
The IVGTT performed in 16-month-old rats showed that DR prevented the development of the moderate glucose intolerance observed in AL rats. The IVGTT performed at 18 months of age confirmed the beneficial effect of DR and showed that VOSO4 was able to prevent the further age-related progression of glucose intolerance observed in AL rats. Pancreas perfusion studies showed that no increase in insulin secretion occurred in both VOSO4-treated and DR rats with respect to the age-matched AL controls, consistently with the in vivo observation of post-loading insulinaemic changes.


CONCLUSIONS
On the basis of these results, we conclude that the beneficial effect of both treatments is mostly related to an improvement of tissue sensitivity to insulin rather than to an insulinotropic effect.
Novelli
Michela
M
Department of Experimental Pathology, Medical Biotechnologies, Infectivology and Epidemiology, University of Pisa, Pisa, Italy.
De Tata
Vincenzo
V
Fierabracci
Vanna
V
Barbera
Michele
M
Rossetti
Raffaele
R
Masiello
Pellegrino
P
D000284:Administration, Oral; D000375:Aging / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000494:pharmacology; D018149:Glucose Intolerance / Q000178:diet therapy* / Q000188:drug therapy* / Q000503:physiopathology; D005951:Glucose Tolerance Test; D006706:Homeostasis / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D008297:Male; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D017968:Vanadium Compounds / Q000008:administration & dosage / Q000627:therapeutic use*
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D017968:Vanadium Compounds; C034028:vanadyl sulfate; D005947:Glucose