Imidazole and yohimbine antagonize hypomotility, penile erection, stretching and yawning induced in rats by BHT 920, a selective dopamine autoreceptor agonist.

When the azepine derivative BHT 920, a putative agonist at dopamine autoreceptors, was injected i.p. into adult male rats at 100 micrograms/kg, it induced numerous penile erections, stretching and yawning and sedation, all considered typical signs of central DA autoreceptor stimulation, but did not elicit stereotyped behaviour. Imidazole (37.5-150 mg/kg i.p.) and the alpha 2 antagonist yohimbine (0.5-1 mg/kg i.p.) both antagonized the behavioural effects of BHT 920. In the light of the proposed selective action of the drugs used, the possible involvement of specific receptors for the modulation of these forms of behaviour, as well the possible relevance of the data presented, are briefly discussed.