Streptozotocin and alloxan produce alterations in rat brain monoamines independently of pancreatic beta cells destruction.

In recent years the effect of experimental diabetes mellitus on brain neurochemistry has been under an intensive investigation. In most of these studies diabetes was produced by a peripheral administration of streptozotocin or alloxan. In line with previous reports, a week after such an application of alloxan (200 mg/kg s.c.) we found the concentration of serotonin, dopamine and norepinephrine to be increased in the brain of a diabetic rat. Accumulation of these monoamines, produced by inhibition of monoamine oxydase with pargyline (100 mg/kg i.p.) decreased in animals made diabetic by alloxan or streptozotocin (100 mg/kg i.p.) suggesting a decrease in deamination rate. Surprisingly, however, one week after an intracerebroventricular administration of non-diabetogenic doses of streptozotocin (5-20 mg/kg) or alloxan (20 mg/kg), changes in brain monoamines were similar to those observed in diabetic animals. This observation apparently suggests that the CNS effect of streptozotocin or alloxan is not necessarily related to a diabetogenic, beta-cytotoxic action of these substances.