Apomorphine-induced alterations in cortical EEG activity of rats. Involvement of D-1 and D-2 dopamine receptors.
EEG activity after activation of dopamine receptors of D-1 and/or D-2 type was studied by using telemetric recordings in rats. Apomorphine, a preferential D-2 agonist, produced a characteristic increase in the power of alpha-1 band (7.00-9.50 Hz) when given in doses mediating stereotypies (0.2 or 0.5 mg/kg s.c.). Low doses produced a general increase in the power of all of the bands except beta-2. In particular, delta activity was enhanced which seems to be in correspondence with the sedation observed after these doses (0.02 and 0.05 mg/kg). Haloperidol in a dose which is assumed to block both D-1 and D-2 receptors (0.1 mg/kg i.p.) completely antagonized the alpha-1 activation produced by apomorphine (0.5 mg/kg). A similar, although not complete inhibition of alpha-1 activation was found after administration of a large dose of the selective D-1 antagonist SCH 23390 (0.2 mg/kg i.p.). The selective agonist at D-2 receptors quinpirole (1.0 mg/kg s.c.) produced a less pronounced activation of the power in the alpha-1 band than apomorphine. In general, there was found to be a good correlation between the activation of the alpha-1 activity and stereotyped behaviour. The results suggest that for the full expression of alpha-1 activation, a pronounced activation of D-2 receptors and at least a minimal activation of D-1 receptors, for instance by the endogenous dopamine, is necessary.
Kropf
W
W
Institute of Pharmacology and Toxicology, Faculty of Pharmacy, University of Marburg, Federal Republic of Germany.
Kuschinsky
K
K
Krieglstein
J
J
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004567:Electrodes, Implanted; D004569:Electroencephalography; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013239:Stereotyped Behavior / Q000187:drug effects; D013686:Telemetry
D001552:Benzazepines; D011954:Receptors, Dopamine; D001058:Apomorphine