On the interpretation of asymmetries of posture and locomotion produced with dopamine agonists in animals with unilateral depletion of striatal dopamine.

CONTENTS 1. Introduction 230 2. Concepts of the functional role of striatal dOpaminergic activity 231 2.1. Introduction 231 2.2. The behavioural actions of dopamine in the striatum: unitary or diverse? 231 2.3. Regional differences in the striatal functions revealed by the actions of dopamine 232 2.4. The side to which the striatum's behavioural effects are referred 232 2.4.1. The traditional view 232 2.4.2. Qualifications to the traditional view 233 2.5. Discussion and conclusion so far 234 3. Evidence, using receptor-selective drugs, that more than one mechanism is involved in turning phenomena 235 3.1. Time course of effects with receptor-selective dopamine agonists 235 3.1.1. Mixed direct agonists such as apomorphine 235 3.1.2. Direct D-2 agonists 237 3.1.3. Direct D-1 agonists 237 3.1.4. Combinations of D-1 and D-2 agonists 237 3.1.5. Discussion of synergism and antagonism between D-land D-2-induced rotatory effects 238 3.1.5.1. Synergic interactions 238 3.1.5.2. Competitive interactions 239 3.2. Challenge with various dopamine antagonists 239 3.2.1. Dopamine antagonists versus mixed agonist 239 3.2.1.1. D-2 antagonists versus mixed agonist 239 3.2.1.2. D-1 antagonists versus mixed agonist 239 3.2.1.3. Mixed antagonists versus mixed agonist 240 3.2.1.4. Conclusions 240 3.2.2. Dopamine antagonists versus selective agonists 240 3.2.2.1. D-2 antagonists versus D-2 agonists 240 3.2.2.2. D-I antagonists versus D-2 agonists 240 3.2.2.3. D-l antagonists versus D-1 agonists 240 3.2.2.4. D-2 antagonists versus D-1 agonists 240 3.2.2.5. Conclusion 240 3.3. Discussion 241 3.3.1. Denervation supersensitivity as a possible means of uncoupling the D-I from the D-2 receptors 241 3.3.2. A possible anatomical basis for the independence of D-1 and D-2 effects 242 4. The behavioural components underlying turning behaviour induced by dopamine agonists, and their regional representation in the striatum 242 4.1. Possible behavioural components underlying turning behaviour 242 4.