Lisuride and transdihydrolisuride: differences in action on central dopaminergic functions in dependence on the location and the state of receptors.

The effects of apomorphine, lisuride and 9, 10 transdihydrolisuride (TDHL) were compared on two models of rotating rat. In rats with 6-hydroxydopamine (6OHDA) induced unilateral lesions, all three drugs evoked contralateral rotation. By contrast, in rats with unilateral electrolytical lesions of the striatum, only apomorphine and lisuride acted as agonists. TDHL did not cause any circling and inhibited rotation induced by apomorphine and lisuride. In other experiments the effects on body temperature was examined. All three drugs lowered the rectal temperature in normal mice; however, only apomorphine and--to some extent--lisuride reversed the hypothermia induced by reserpine. Both lisuride and TDHL inhibited the hypothermia reversal induced by apomorphine. The presented results are interpreted in terms of lower intrinsic activities of TDHL and lisuride in comparison with apomorphine. The lower intrinsic activity is manifested as partial agonist or antagonist type of action in dependence on the location and the state of receptors.