Abstract
The effect of various stressors of different intensity applied in random order before the final single immersion restraint stress was tested in two inbred rat strains. isoprenaline-sensitive and isoprenaline-resistant. The isoprenaline-sensitive strain revealed higher incidence of heart lesions after this single acute stress and low incidence of gastric lesions.
The isoprenaline-resistant strain had the opposite characteristics, These differences were constantly reproducible when this strong stressor was used. After prestress by different stressors (tail-flick, ether anaesthesia, Porsolt swimming stress) ar different time schedules, the incidence of gastric ulcer lesions, the weight of organs (heart, adrenals, spleen) changed substantially in isoprenaline-sensitive rats only.
The most important result was reversal of the extent of gastric lesions. The isoprenaline-sensitive strain revealed more lesions than the isoprenaline-resistant one.
The repeated different prestressors mainly changed the reactivity of animals, isoprenaline-sensitive rats becoming more similar to isoprenaline-resistant rats. These findings urged us to interpret carefully the results obtained in stress research with different and multiple stressors both in animals and humans.