Behavioral effects of ivermectin in mice

Background and Purpose: Ivermectin is a common anthelmintic drug, widely used in laboratory rodents for treatment of pinworm and mite infestations. We evaluated the action of ivermectin on sensitive behavioral tasks in mice during treatment for mites within a barrier facility. Methods: A total of 21 (5 males, 16 females) mice (129/SvEv) were used for measuring body weight, open field locomotor activity, and rotarod motor coordination. For acoustic startle and prepulse inhibition, 20 C57BL/6J and 29 AKR/J mice were studied. For the Morris water task, the same 20 C57BL/6J mice were studied. Ivermectin (0.08% sheep drench) was administered in the drinking water of the home cage for 8 weeks. Control groups received normal tap water in identical bottles. Results: Ivermectin did not affect general health, body weight, motor coordination, swimming behavior, or spatial learning in several inbred strains of mice. However, it induced a small but significant effect on some sensitive behaviors. Conclusions: A cautious approach to initiating ivermectin treatment in mice should be used for sensitive behavioral experiments.