title: Genotypic influences on striatal dopaminergic regulation in mice.
abstract: Genotypic influences on dopaminergic-induced behaviors and striatal dopaminergic receptors were evaluated in CBA/J, C57BL/6J and BALB/cJ male mice. CBA/J mice were less behaviorally sensitive to apomorphine (stereotypic behavior) but more sensitive to haloperidol (catalepsy) than C57BL/6J and BALB/cJ mice. Striatal dopaminergic receptors, assayed by binding of [3H]spiroperidol (antagonist) and [3H]ADTN (agonist), were 50% fewer in CBA/J compared to BALB/cJ mice; C57BL/6J mice had low to intermediate numbers of receptors. Striatal dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) concentrations were similar in all strains. However, a 20% higher DOPAC/dopamine ratio in CBA/J mice suggests greater dopamine turnover. Median eminence dopamine was similar in all strains, but norepinephrine was 30% higher in BALB/cJ mice. CBA/J mice failed to show antagonist-induced supersensitivity-type responses to chronic haloperidol treatment: enhanced stereotypic response to apomorphine and a 30% increase of dopaminergic receptors occurred in C57BL/6J and BALB/cJ mice, but not in CBA/J mice. These data suggest that CBA/J mice either cannot respond to chronic haloperidol treatment or have an elevated threshold for induction of supersensitivity response. Chronic treatment with the dopamine agonist bromocriptine (7d) depressed apomorphine-induced stereotypic behavior in C57BL/6J mice and eliminated stereotypy in BALB/cJ mice, but caused no change in stereotypic behavior in CBA/J mice. Dopaminergic receptors were 15% lower after bromocriptine treatment in all strains. These results suggest that some striatal dopaminergic functions are impaired in CBA/J mice relative to BALB/cJ and C57BL/6J mice. The impaired haloperidol-induced supersensitivity responses in the CBA/J mouse may be a useful model for analyzing similar impairments of supersensitivity responses in old rodents.
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D005838:Genotype; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000502:physiology; D013045:Species Specificity; D013239:Stereotyped Behavior / Q000187:drug effects
chemical_list: D011943:Receptors, Adrenergic, beta; D006220:Haloperidol; D001058:Apomorphine; D004298:Dopamine