Quantification of rigidity and tremor activity in rats by using a new device and its validation by different classes of drugs.

Subjective techniques employed for measuring skeletal muscle tone and tremor, leading symptoms of several diseases, have certain limitations. Objective methods are usually more sensitive and accurate. The equipment developed by the authors allows the objective and rapid measurement of experimentally induced rigidity and tremor in the same small laboratory animal (rat). The present method considerably reduces the number of animals needed to investigate the activity of drugs, especially when compounds should be screened. Due to the greater sensitivity of the equipment, doses of reserpine and oxotremorine which do not cause any postural, autonomic or parasympathetic symptoms can be used to induce muscular rigidity and tremor. Therefore, not only the number of animals but also their stress can be reduced. It was possible to differentiate the oxotremorine-induced tremor from the spontaneous motor activity and to determine qualitative differences in tremor caused by antitremor agents. A number of clinically effective muscle relaxants and antiparkinsonian drugs were examined in this model in order to determine its utility.