The pharmacological effect of thyrotropin-releasing hormone on ataxic mutant mice.

The Rolling mouse Nagoya (RMN), Staggerer, Weaver and Reeler, all of which show hereditary ataxia, were intraperitoneally injected with 25 mg/kg of thyrotropin-releasing hormone (TRH-T) or physiological saline, and changes in the motions of these animals were observed by an Animex II and an open field method. All four strains of mice with ataxia showed improvement of ataxia and an increase in the motion volume, but these changes were not necessarily consistent in degree. Improvement of ataxia was most marked in the RMN and the Staggerer, moderate in the Weaver and slight in the Reeler, which showed enhanced tremor. The relationship between the competence of transmitting information in the cerebellum and improvement of ataxia by the injection of TRH-T aroused our interest.