A new universal rat restrainer for ophthalmic research.

Purpose: Immobilization of rats is required in many psychological and physiological experiments. The aim of the current paper was to invent a universal device allowing for adaptation of rats of a wide age range and to maximize convenience for in vivo exposure to optical radiation under not-anaesthetized conditions.

Methods: Eighty-three 6-week-old and three 18-week-old Sprague-Dawley albino female rats were progressively familiarized daily with the restraining device 5 days prior to exposure to acquire a conditioned response and to reduce stress. After initial habituation, 10 min preceding the ultraviolet radiation (UVR) exposure, the animal was fixed in the rat restrainer. Each unanaesthetized animal was unilaterally exposed to a single dose of 8 kJ/m² UVR-300 nm for 15 min. Three of the 6-week-old and three of the 18-week-old rats were in vivo exposed to UVR once for 10 consecutive days.

Results: All rats acclimatized well to immobilization in the restrainer. Young rats adapted quicker than older rats. The device prevented head movement and body rotation, which allowed for uncomplicated single as well as repeated in vivo exposures to UVR.

Conclusions: The restrainer effectively immobilizes unanaesthetized rats in the age range 6-18 weeks old, making it useful in future projects involving chronic repeated in vivo exposure of the eye to UVR.