Effects of naloxone and neuroleptic drugs on muscle rigidity and heart rate of the nervous Pointer dog.

Muscle rigidity, a persistent physiological characteristic of the nervous Pointer dog, is not only attenuated by the major neuroleptic drugs, haloperidol and pimozide but also by naloxone. In addition, naloxone administration results in a modest but significant increase in heart rate of these subjects. The data obtained in this study add support for the concept that an abnormality in central nervous system dopaminergic function is involved in the genesis of abnormal behavior of this animal model.