Effects of nitrendipine and nisoldipine on biogenic amines in discrete areas of rat brain

Abstract

1. 1. Biogenic amines and metabolites were determined in discrete brain sections obtained from rats once or repeatedly treated with nitrendipine or nisoldipine. 2. 2. The increase in both the 5-HIAA levels and the 5-HIAA/5-HT ratio suggested that the drugs activated the serotonergic system in various brain areas. 3. 3. Moreover, nisoldipine decreased the HVA content and the HVA/DA ratio in the striatum. 4. 4. This suggested that nisoldipine, but not nitrendipine, inhibited dopaminergic neurotransmission in this brain area. 5. 5. The effects induced by repeated treatment with nitrendipine or nisoldipine were reduced as compared to those caused by a single administration of these drugs. 6. 6. All these facts could be explained on the basis of the pharmacokinetic properties of nitrendipine and nisoldipine and by the ability of these drugs to interact with the brain VSCC.