BEHAVIORAL-EFFECTS OF THE DOPAMINE D-3 RECEPTOR AGONIST 7-OH-DPAT IN RATS

The putative selective dopamine (DA) D-3 receptor agonist, 7-OH-DPAT ( 25-4000 mu g kg(-1)), enhanced stretching-yawning and penile erection in male rats, besides respectively increasing and decreasing sedation at low (25-200 mu g kg(-1)) and high (1600 and 4000 mu g kg(-1)) doses and inducing stereotypy from 800 mu g kg(-1) upwards. The DA D-2 anta gonist, (-) eticlopride (10 and 20 mu g kg), antagonized stretching-ya wning and penile erection induced by a low dose of 7-OH-DPAT (50 mu g kg(-1)) but not those produced by high doses (1600 and 4000 mu g kg(-1 )), when stereotyped behaviour, on the other hand, was potently inhibi ted. Comparative experiments performed with the DA agonist SND 919 gav e similar results. (C) 1995 The Italian Pharmacological Society