The role of multiple dopamine receptors in apomorphine and N-n-propylnorapomorphine-induced climbing and hypothermia.

Abstract

Apomorphine and N-n-propylnorapomorphine (NPA) were compared for their ability to induce stereotyped cage climbing and hypothermia in mice. Climbing behavior was produced by similar doses of apomorphine and NPA (0.625-2.5 mg/kg s.c.), whereas NPA was 43 times more potent than apomorphine in inducing a hypothermic response. SKF38393 caused a shift to the left in the dose-response curve for NPA-induced climbing, the ED50 changing from 0.98 to 0.014 mg/kg. SKF38393 had no effect on apomorphine-induced climbing behaviour. The climbing response produced by apomorphine was antagonised by both D-1 and D-2 antagonists. Climbing behaviour induced by NPA (2.5 mg/kg) could be antagonised by SCH23390 but not by clebopride, however climbing behaviour induced by a low dose of NPA (0.06 mg/kg) plus SKF38393 could be blocked by both D-1 and D-2 receptor antagonists. The hypothermic responses produced by either apomorphine or NPA could only be reversed by the selective D-2 antagonist, clebopride. These results demonstrate that dopamine agonist-induced stereotyped cage climbing requires both D-1 and D-2 receptor stimulation, whereas the hypothermic response is D-2-mediated. The results also show that it is possible to assess the relative activity of a dopamine agonist at D-1 or D-2 receptors in vivo by comparing the ability of the compound to induce hypothermia and climbing behaviour.

• Authors: N A Moore, M S Axton
• Journal: European journal of pharmacology (Eur J Pharmacol) Vol. 178 Issue 2 Pg. 195-201 (Mar 20 1990) ISSN: 0014-2999 [Print] Netherlands
• PMID: 2184043 (Publication Type: Journal Article)

Chemical References

• Benzamides
• Benzazepines
• Ergolines
• Receptors, Dopamine
• Quinpirole
• N-n-propylnorapomorphine
• 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine
• clebopride
• Apomorphine

Topics

• 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (pharmacology)
• Animals
• Apomorphine (analogs & derivatives, pharmacology)
• Benzamides (pharmacology)
• Benzazepines (pharmacology)
• Body Temperature (drug effects)
• Dose-Response Relationship, Drug
• Ergolines (pharmacology)
• Female
• Mice
• Quinpirole
• Receptors, Dopamine (drug effects)
• Stereotyped Behavior (drug effects)