The D1 agonist, SKF 38393, failed to induce contralateral turning in drug-naive rats lesioned unilaterally with 6-hydroxydopamine from 17 days. Priming with a dopamine agonist, such as the D2 agonist, LY 171555, three days before, made SKF 38393 fully effective in inducing contralateral turning. Analysis of D1 receptor binding in striata of drug-naive and primed rats showed no change in the Bmax and Kd. In contrast, dopamine-stimulated adenylate cyclase showed a decrease in its Km for dopamine in the lesioned side of primed rats as compared with drug-naive rats. Thus, priming appears to elicit changes at the level of the transduction mechanism of D1 receptors rather than in the D1 recognition site itself.
Changes in the D1 receptor-adenylate cyclase complex after priming
MORELLI, MICAELA;DI CHIARA, GAETANO
1990-01-01
Abstract
The D1 agonist, SKF 38393, failed to induce contralateral turning in drug-naive rats lesioned unilaterally with 6-hydroxydopamine from 17 days. Priming with a dopamine agonist, such as the D2 agonist, LY 171555, three days before, made SKF 38393 fully effective in inducing contralateral turning. Analysis of D1 receptor binding in striata of drug-naive and primed rats showed no change in the Bmax and Kd. In contrast, dopamine-stimulated adenylate cyclase showed a decrease in its Km for dopamine in the lesioned side of primed rats as compared with drug-naive rats. Thus, priming appears to elicit changes at the level of the transduction mechanism of D1 receptors rather than in the D1 recognition site itself.
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