The effects of concurrent D-1 and D-2 dopamine receptor blockade with SCH 23390 and eticlopride, on bombesin-induced behaviours.
1. The objective of the current study was to assess the effect of concurrent D-1 and D-2 receptor blockade on bombesin (BN)-induced grooming and locomotion on the premise that dopamine could be mediating the behavioural effects of BN. 2. Rats implanted with ventricular cannulae were pretretreated systemically with SCH 23390 and/or eticlopride (ETIC) followed by BN (0.5 ug/3 ul; i.c.v.). Grooming and locomotory activity were assessed for 60 min. 3. Individually, SCH 23390 (0.033 mg/kg) and ETIC (0.05 mg/kg) significantly inhibited BN-elicited grooming but not locomotion. Combining ETIC (0.05-0.1 mg/kg) with the fixed dose of SCH 23390 (0.033 mg/kg) significantly inhibited both behaviours in a dose dependent manner with a greater effect on locomotion. Adding SCH 23390 (0.033-0.075 mg/kg) to ETIC (0.05 mg/kg) inhibited both behaviours in a dose dependent manner with a more pronounced effect on grooming. At the combination dosages utilized, SCH 23390 and/or ETIC failed to significantly alter baseline behaviours in control conditions. It is thus concluded that both dopamine receptor subtypes are involved in the expression of BN-induced behaviours with D-1 appearing to have a greater involvement with grooming and D-2 locomotion.
Piggins
H
H
School of Psychology, University of Ottawa, Ontario, Canada.
Merali
Z
Z
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D001839:Bombesin / Q000008:administration & dosage / Q000494:pharmacology*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D018492:Dopamine Antagonists; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012016:Reference Values; D012457:Salicylamides / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects*
D001552:Benzazepines; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012457:Salicylamides; C045989:eticlopride; D001839:Bombesin