mise à jour du 25 avril 2002
Br J Pharmacology
1989; 98;1312-1318 
cas cliniques
The effects of dihydropyridine compounds in behavioural tests of doparninergic activity  
 Anne Bourson, Alma Gower, Anis K Mir & Paul C Moser
Merrell Dow Research Institute, 16, rue d'Ankara, 67084 Strasbourg Cedex, France


1 The effects of the dihydropyridine calcium channel blocker nifédipine and the activator Bay K 8644 were investigated in different behavioural tests involving dopaminergic systems. These were the discriminative stimulus induced by amphetamine, rotational behaviour in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions and apomorphine-induced yawning in rats.

2 The yawning induced by apomorphine (40,ugkg-'s.c.) was significantly potentiated by nifedipine (5-10mgkg-'i.p.). Bay K 8644 (0.05-0.5mgkg-'i.p.) dose-dependently inhibited yawning induced by apomorphine (80,ugkg-'s.c.) and, at 0.4mgkg-', inhibited the nifedipine potentiation of apomorphine-induced yawning. In contrast to their effects on apomorphine-induced yawning, nifedipine and Bay K 8644 had no effect on apomorphine-induced pende erection.

3 Bay K 8644 (0.06-0.5mgkg-'i-p.) and nifedipine (5-20mgkg-'i.p.) had no dose-relate effect on the discrimination performance of rats trained to discriminate amphetamine from saline. However, nifedipine dose-dependently reduced the response rate of amphetamine-treated rats. Bay K 8644 had no effect on this measure except at high doses that also caused disruption.

4 Neither nifedipine(5-10mgkg-'i.p.) nor Bay K 8644(0.06-0.5mgkg-'i.p.)a ffected the turning behaviour induced by amphetamine (1mgkg-'i.p.) in rats with unilateral 6-OHDA lesion of the medial forebrain bundle, and did not induce turning themselves.

5 As the dihydropyridine compounds affected apomorphine-induced yawning but not penile erection, and did not affect amphetamine-induced rotation or drug discrimination, it seems unlikely that they are affecting dopamine release in vivo.