Super-stereotypy II: Enhancement of a complex movement sequence by intraventricular dopamine D1 agonists

This study compared the effect of intraventricular administration of dopamine D1 or D2 agonists or of ACTH on the sequential stereotypy of a serial pattern of grooming movements ("syntactic chain"). In a previous study, we showed that peripheral administration of D1 agonists increased the probability of occurrence and enhanced the stereotypy of the already-stereotyped movement pattern. Here we made microinjections of either SKF 38393 (a partial D1 agonist; 5, 10, 15, 20, 40 microg), SKF 82958 (a full D1 agonist; 5, 10, 20 microg), quinpirole (a D2 agonist; 5, 10, 20 microg), or ACTH-(1-24) (2, 5, 10 microg) into the lateral ventricles of rats. We measured the amount of grooming, the relative probability that the complex sequence pattern would occur, and the degree to which the syntactic pattern was completed faithfully. The total amount of grooming behavior was increased by intraventricular SKF 82958 and by ACTH, but was not changed by SKF 38393 and was decreased by quinpirole. Super-stereotypy of the sequential pattern was produced only by dopamine D1 agonists. The relative probability of initiating the syntactical sequence was increased by both SKF 38393 and SKF 82958, but was reduced by quinpirole and ACTH. The full D1 agonist, SKF 82958, also increased the likelihood that the pattern would be completed, thus causing sequential super-stereotypy in the strongest sense. Our results highlight a role for dopamine D1 receptors, probably within the basal ganglia, in the production of sequential super-stereotypy of complex behavioral patterns.