Essential conservation of D1 mutant phenotype at the level of individual topographies of behaviour in mice lacking both D1 and D3 dopamine receptors.

RATIONALE: In the absence of agonists and antagonists evidencing appropriate selectivities, individual and interactive properties of D(1) and D(3) dopamine receptors would be illuminated most powerfully by their co-deletion.
OBJECTIVES: To define and contrast the behavioural phenotype of D(1)/D(3) double knockout mice in comparison with wild types, and with individual D(1) and D(3 )mutants.
METHODS: Behavioural phenotype was characterised using an ethologically based topographical technique.
RESULTS: On comparison with wild types, D(1)/D(3) double mutants were characterised topographically as follows: increases in sniffing and locomotion, which evidenced delayed habituation; reductions in rearing free, rearing seated, grooming, chewing and stillness. Though the D(1)/D(3) double mutant ethogram comprised elements of both single mutant D(1) and D(3) lines, this phenotype was largely reflective of the D(1) mutant component.
CONCLUSIONS: Distinct patterns of initial exploratory behaviour and of temporal change over subsequent habituation were evident across the three genotypes, with particular conservation of the D(1) phenotype in D(1)/D(3 )double mutants. Under the present conditions, there was little systematic evidence for D(1):D(3) interactions in the regulation of these aspects of behaviour.