THE EFFECT OF ANTIHISTAMINIC DRUGS UPON THE PERFORMANCE OF TRAINED RATS

The side reactions most frequently observed in man after administration of antihistaminic drugs, such as drowsiness, dizziness, and general sedation, indi-cate that these compounds often depress the activity of the higher centers of the central nervous system. Very few studies of these effects have been made in animals. Winter (1948) found that antihistaminic drugs potentiate the hypnotic effect of barbiturates, and two reports of the effect of these compounds upon trained rats have appeared in the form of brief abstracts (Macht and Hoffmaster, 1948; Winter and Flataker, 1949). This paper is a detailed report of the experi-ments upon which the latter abstract was based. MATERIALS AND METHODS. Holtzman male rats, weighing 100 to 150 gm. were used in these experiments. Each animal was used repeatedly, and discarded when the body weight reached about 200 gm. The animals were trained to climb a vertical rope a distance of 172 cm. The method used was similar to that described by Macht (1943). The rats were fasted overnight, and a dish of food placed on a platform at the top of the rope constituted an inducement for climbing. The time required for the animal to negotiate the standar