Thymectomy-induced deterioration of learning and memory in mice

Male ddY mice were thymectomized 4 weeks after birth. Learning behaviors, tested in passive and active avoidance performances and in a spatial memory task, were significantly impaired in thymectomized mice at 10 months after thymectomy, in addition to the reduced immune response. Contents of hypothalamic norepinephrine and hypothalamic choline acetyltransferase activity were significantly increased in thymectomized mice. These results suggested that thymectomy at young adult life in mice not only impaired the immune response, but also deteriorated the learning and memory ability.