Pharmacology Biochemistry andBehavior, Vol. 45, pp. 117-122,1993 0091-3057/93$6.00 + .00 Printedin the U.S.A.All rights reserved. Copyright© 1993Pergamon Press Ltd. Behavioural Profile in the Chicken of CQ 32-084 and CQP 201-403, Two Dopamine Agonists FRANCESCA FERRARI, 1 F. PELLONI AND D. GIULIANI Institute of Pharmacology, University of Modena, Via G. Campi 287, 1-41100 Modena, Italy Received 23 July 1992 FERRARI, F., F. PELLONI AND D. GIULIANI. Behaviouralprofile in the chicken of CQ 32-084 and CQP 201-403, two dopamine agonists. PHARMACOL BIOCHEM BEHAV 45(1) 117-122, 1993.-CQ 32-084 and CQP 201-403, two ergot derivatives that previous behavioural studies in rats had suggested to be differently active on dopamine (DA) receptors, were IP injected into male chickens. Both compounds strongly modified the animals' behaviour. CQ 32-084 led to sedation, increased yawning, and decreased preening, while CQP 201-403 exerted a biphasic activity: At a low dose, it elicited sedation and yawning; at high doses, however, it induced a state of excitation manifested by diminished sedation and yawning, enhanced preening, and pecking. The sedation, increased yawning, and decreased preening induced by the two DA agonists were reversed by the D2-selectiveantagonist, sulpiride. The present studies indicate that, from a behavioural point of view, chickens respond similarly to rats to the DA agonists CQ 32-084 and CQP 201-403, which differ in their selectivityof action on the various DA receptor subtypes. CQ 32-084 CQP 201-403 Dopamine receptors Chickens Yawning Sedation Preening Pecking DOPAMINE (DA) agonlst-induced behavioural effects have been widely investigated in rodents but only rarely in avians despite the fact that catecholamines are present in high con- centrations in their CNS (20). Early studies clearly implicate DA receptor activation in the stereotyped pecking elicited by the mixed D~/D2 agonist, apomorphine (5,6), in accordance with the results obtained in rats, where apomorphine at high doses typically induces stereotyped behaviour (SB). However, since the discovery of the two DA receptor subtypes, D I and D 2 (21,32), several forms of rat behaviour besides SB, which seems to depend upon DI/D 2 synergy (4,23,35), have been identified that are able to distinguish between specific D~ and D 2 activation. It is accepted, for example, that grooming is increased by D I- selective agonists (25,31) but inhibited by D2 agonists (14- 16,27); it is also well documented that sedation (11) and a typical stretching-yawning (SY) syndrome (11,13,24,29,33,34) are induced by all D 2 stimulants, at least over a certain dose range. The latter two behavioural effects are visible after the administration of DA agonists at doses too low to elicit SB and also after selective D 2 autoreceptor agonists (11,24); moreover, they are suppressed by pretreatment with specific D 2 autoreceptor antagonists (27). It has therefore been pro- posed that they are the expression of selective activation of D 2 autoreceptors (11,27,33,34), presynaptically located (21) or, alternatively, of particular D 2 postsynaptic receptors, which are similar to autoreceptors in their sensitivity to DAergic drugs (24,29). The present experiments were performed to compare the behavioural profile in chickens of two ergot derivatives de- scribed as having an agonistic influence on DA receptors (17) and as inducing distinct behavioural effects in rats (12), thus suggesting a different underlying affinity for the DA receptor subtypes. METHOD The subjects were 8- to 10-week-old male Sever chickens (Morini, S. Polo d'Enza, Reggio Emilia, Italy) weighing 500- 700 g. They were housed in groups of 10, with food and water ad lib and on a 12 L : 12 D cycle (light 7:00 a.m.-7:00 p.m.) for at least 1 week prior to the start of the tests. All the tests were performed between 9:00 a.m. and 1:00 p.m. in a soundproof, air-conditioned room, and the animals were observed by experimenters unaware of the experimental design. Each chicken was used only once and the controls were handled similarly to the treated animals (no less than eight for each treatment group). Immediately after the IP in- jection of CQ 32-084, CQP 201-403, or saline, the animals were transferred in pairs to glass observation cages (40 x 30 × 34 cm). The test started 10 min later and lasted 30 rain, no less than four experiments being performed for each treatment 1 To whom requests for reprints should be addressed. 117