Diphenylhydantoin and Procainamide: Normalization of Suboptimal Learning Behavior

In this paper we explore positive drug effects on the learning behavior of two classes of rats characterized by learning deficit—the aged rat and the young adult rat made deficient by a procedure involving the intraperitoneal injection of 10–20% body weight of 5.5% dextrose, originally developed by Darrow and Yannet [1]. This procedure lowers the electroconvulsive-shock threshold, while increasing brain intracellular water and sodium and decreasing total brain electrolytes [2]. Because of their lowered electroconvulsive-shock threshold, rats so treated have been used to evaluate anticonvulsant drugs [2]. That animals so treated also manifest a learning deficit represents a new finding of our laboratory. It will be specifically shown that these animals reflect aspects of the deficit that develops with aging, thereby constituting a limited model for this condition.