Changes in brain monoaminergic neurotransmitter concentrations in rat after intracerebroventricular injection of streptozotocin.

The tissue concentrations of the monoaminergic neurotransmitters noradrenaline (NA), dopamine, and serotonin (5-HT) and of their major metabolites were measured by HPLC and electrochemical detection in several rat brain areas after intracerebroventricular injection of streptozotocin (STZ). NA levels were found to be decreased in the frontal cortex by 14%, in the entorhinal cortex by 18%, and in the striatum by 38%. In the entorhinal cortex, 5-HT levels were decreased by 19% and the 5-HT turnover rate, measured as the 5-hydroxyindoleacetic acid/5-HT ratio, was found to be increased by 48%. These results may be indicative of a distinct susceptibility of some neurotransmitters in certain brain areas after a more general impairment of brain metabolism by means of intracerebroventricular application of the diabetogenic compound STZ.