Different effects of apomorphine on climbing behavior and locomotor activity in three strains of mice.

Apomorphine (0.1, 0.25, 0.5, 1, 3 mg/kg, SC), induces a dose-dependent reduction of locomotor activity in DBA/2(DBA) and BALB/c(BALB) mice, while it enhances locomotor activity in a biphasic way in C57BL/6(C57) mice. On the other hand, apomorphine is ineffective in modifying climbing behavior in DBA mice while it increases climbing behavior in C57 and BALB mice. The results, taken together, suggest that these are two different behaviors, possibly controlled by different dopaminergic mechanisms depending on the genetic makeup.