Effect of nimodipine on brightness discrimination learning test in Wistar Kyoto and spontaneously hypertensive rats.

Nimodipine (Nimotop) was administered to spontaneously hypertensive rats (SHR) in order to investigate its ameliorative effect on central nervous disorders associated with hypertension. Discrimination learning was used as the dependent variable. In normotensive Wistar Kyoto rats, the ratio of correct: incorrect responses in a brightness discrimination was not different between the nimodipine group and the vehicle group. However, SHR, which displayed decreased discrimination learning ability under control conditions, showed a remarkable improvement in discrimination learning under the influence of nimodipine. This was probably because the vasodilative action of nimodipine produced improvements in circulation in various organs including the brain, which in turn influenced learning ability. Nimodipine has very effective actions on learning performance that low levels of discrimination ability in SHR might be improved on learning performance on schedule controlled learning task.