Systematic comparison of apomorphine-induced behavioral changes in two mouse strains with inherited differences in brain dopamine receptors.
Dosage and time dependencies of apomorphine-induced changes in stereotyped behaviors (climbing, gnawing and sniffing), locomotor activity and rearing activity were compared in young adult male mice of two inbred strains, DBA/2 and C57BL/6. These two strains are known to differ in their genetically specified brain dopamine receptor number. Apomorphine administered intraperitoneally at dosages of 0.5-20 mg/kg failed to induced stereotyped climbing in DBA/2 at any of the doses tested but markedly increased climbing in C57BL/6 at higher dosages. Apomorphine-induced stereotyped gnawing occurred in both strains at higher dosages although the latency was shorter and maximal effect greater in C57BL/6. Stereotyped sniffing was induced in both strains to a comparable degree at doses greater than or equal to 2.0 mg/kg, and the duration of this stereotypy was indistinguishable between strains. Locomotor activity was inhibited maximally in DBA/2 at an apomorphine dosage of 2 mg/kg and was inhibited to a greater extent than was C57BL/6. Rearing was inhibited in both strains by doses of apomorphine greater than or equal to 0.5 mg/kg; however the duration of the effect was considerably greater in DBA/2 than in C57BL/6. These data suggest that genetically determined differences in central dopamine receptors may have profound and selective effects on behaviors mediated by dopamine pathways; that complex behavioral patterns, e.g., apomorphine-induced stereotypy, may be dissected in to individual components by identifying neuropharmaco genetic differences between strains; that marked strain-specific, inherited differences in dopamine agonist-induced behavioral changes do occur among inbred, non-mutant mouse strains and that their occurrence in other mammalian species including man should be considered.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000378:metabolism; D005106:Exploratory Behavior / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009043:Motor Activity / Q000187:drug effects; D011954:Receptors, Dopamine / Q000502:physiology*; D013045:Species Specificity; D013239:Stereotyped Behavior / Q000187:drug effects; D013997:Time Factors
D011954:Receptors, Dopamine; D001058:Apomorphine