Central mechanisms involved in the occurrence of oral dyskinesia

In rats treated chronically with antipsychotics，the display of spontaneous vacuous chewing is often considered as a valid animal model of tardive dyskinesia.Its face validity is underlined by the fact that both morphology and the onset of the oral movements elicited in rats bear a certain resemblance to that seen in man。However，its predictive validity by the fact that a long-term treatment with haloperidol，but not clozapine，increases vacuous chewing is not yet clear.This study revealed that both treatments similarly increased the behavious，showing that this paradigm was insufficient for predicting the drug-induced occurrence of oral dyskinesia in man。Changes in oral movements were objectively and reliably assessed with the help of the techinique，in which jaw movements are recorded by means of light-emitting diode attached to the mandible.Both apomorphine and a mixture of D I D21文件D2 and D文件D22文件D2 receptor agonists increased jaw movements in haloperidol-treated but not clozapine-treated rats.The results show that the chosen pharmaco-behavioural assay is a new animal model of tardive dyskinesia that has predictive validity.This study also examined the modulation of the different patterns of repetitive jaw movements，evoked by D I D21西耶D2/D I D 22西耶D2 receptor cholinoceptor stimulation in the ventrolateral striatum，by GABA I D 2 Aii receptors located in the dorsolateral part of the substulium，Moreover，this study examined the modulation of repetitive jaw movements，evoked by D I D21文件D2/D文件D22文件D2 receptor stimulation in the nucleus accumbens shell，by GABA文件D2A文件D2 receptors located in the ventral pallidum and retrorubral field。The results demonstrate that GABA锡D2A琴D2 receptors in the brain sites examined can differentially modulate jaw movements elicited by dopaminergic and cholinergic stimulation.

In rats treated chronically with antipsychotics, the display of spontaneous vacuous chewing is often considered as a valid animal model of tardive dyskinesia. Its face validity is underlined by the fact that both morphology and the onset of the oral movements elicited in rats bear a certain resemblance to that seen in man. However, its predictive validity by the fact that a long-term treatment with haloperidol, but not clozapine, increases vacuous chewing is not yet clear. This study revealed that both treatments similarly increased the behavious, showing that this paradigm was insufficient for predicting the drug-induced occurrence of oral dyskinesia in man. Changes in oral movements were objectively and reliably assessed with the help of the techinique, in which jaw movements are recorded by means of light-emitting diode attached to the mandible. Both apomorphine and a mixture of DィイD21ィエD2 and DィイD22ィエD2 receptor agonists increased jaw movements in haloperidol-treated but not clozapine-treated rats. The results show that the chosen pharmaco-behavioural assay is a new animal model of tardive dyskinesia that has predictive validity.This study also examined the modulation of the different patterns of repetitive jaw movements, evoked by DィイD21ィエD2/DィイD22ィエD2 receptor or cholinoceptor stimulation in the ventrolateral striatum, by GABAィイD2AィエD2 receptors located in the dorsolateral part of the substantia nigra pars reticulata, entopeduncular nuckeus, ventral pallidum and superior colliculus. Moreover, this study examined the modulation of repetitive jaw movements, evoked by DィイD21ィエD2/DィイD22ィエD2 receptor stimulation in the nucleus accumbens shell, by GABAィイD2AィエD2 receptors located in the ventral pallidum and retrorubral field. The results demonstrate that GABAィイD2AィエD2 receptors in the brain sites examined can differentially modulate jaw movements elicited by dopaminergic and cholinergic stimulation.