engleski

Impaired glucose tolerance following the central administration of non-diabetogenic dose of alloxan and streptozotocin in rats

Alloxan and streptozotocin are well-known betacytotoxics, that in high doses (>30 mg/kg) are usually used for causing the experimental diabetes mellitus. Their influence upon the glucose tolerance following the low, non-diabetogenic doses has not been reported. We have performed oral glucose tolerance test /OGTT/ in rats, seven days following the intracerebroventricular (icv) administration of a low, non-diabetogenic dose (500 mg/kg) of alloxan and streptozotocin, respectively. A water solution of D-glucose (2.5 g/kg body weight) was given orally by oro-gastric catheter to conscious, male, Wistar rats (160-200 g). Blood samples were drawn from the tail vein before and at 30, 60, 90 and 120 minutes following OGTT, respectively. Plasma glucose concentrations were measured by the glucose oxidase method. Normoglycemic, pre-OGTT plasma glucose values were found in all betacytotoxic-treated and control groups, respectively. However, post-OGTT values demonstrated lower plasma glucose levels in alloxan- and streptozotocin-icv treated animals, being statistically significant 30 min following the OGTT. Thus, icv-treatment with low doses of these betacytotoxics, known to be selectively toxic to insulin-producing cells, does not alter blood glucose level, but impairs glucose tolerance, suggesting that alloxan and streptozotocin administered icv in doses at least 60 times lower than diabetogenic ones, regulates glucose metabolism by acting directly on the brain.

diabetes mellitus; brain; glucose tolerance

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