[Behavior of nervous tissue during long-term administration of diphenylhydantoin to cats].

The purpose of the study was to assess the morphological changes in the brain of cats reveiving diphenylhydantoin in therapeutic doses during several weeks. The material included 20 cats: 14 experimental and 6 control. In conditioned behaviour the animals showed a steady reduction in the number of correct responses to positive stimuli, statistically significant prolongation of the mean time of latent reaction and disappearance of reaction in intervals between signals. The general condition of the animals changed also, they became somnolent, refused to take food or water. Trophic changes included weight loss, spot-like loss of hair and loss of hair lustre, mucosal bleeding. These changes developed already in the first weeks on the drug administration independently of the dose. Morphological investigations of cat brains showed greatest cell loss and different grades of damage of the surviving cells in Ammon's horn, amygdala and in brain stem reticular formation. Glial proliferation and hypertrophy were slight. The authors discuss the problem of importance of the observed changes for development of "clinical" syndrome in experimental cats.