RESPONSE TO ALARM SUBSTANCE IN DIFFERENT RAT STRAINS

Two studies were conducted. In the first study, four strains of male rats-Long-Evans (LE), Sprague-Dawley (SD), Wistar, Fisher 344-were immersed in fresh water or water soiled by a rat of the same strain which presumably contains an alarm substance. LE rats were less immobile than SD, Wistar, and Fisher rats in fresh water. All strains were significantly less immobile in soiled water; however, relative to immobility times in fresh water, the decrease in immobility in soiled water was greatest for SD rats and least for Wistar rats. A second study tested SD and Wistar rats in water soiled by animals of the same strain compared to water soiled by animals of the other strain. This study indicated that Wistar rats produce less alarm substance or less potent substance and are also less reactive to it than SD rats. The results of these two studies indicate that some strains are more affected by alarm substance than others and the differential response is due both to decreased production/potency and reaction to the substance.