Catecholamine turnover in rat cerebral cortex and caudate following repeated treatment with dihydroergotoxine

The turnover rate of catecholamine in the cerebral cortex and caudate of adult Wistar rats was estimated after inhibition of synthesis by means of alpha-methyl-rho-tyrosine in animals treated with dihydroergotoxine (1 mg/kg body weight daily) for 1, 3 and 10 days. Following single as well as repeated treatments with the drug, blockade of norepinephrine receptors, as indicated by the increased catecholamine turnover rate, was found in both brain structures. The turnover rate of dopamine was changed only after repeated treatments; it was decreased in the cortex and increased in the caudate, indicating both agonistic and antagonistic effects of dihydroergotoxine on dopamine receptors.