INFLUENCE OF AGE, SEX, AND COLD EXPOSURE ON SUSCEPTIBILITY TO RESERPINE-INDUCED GASTRIC LESIONS

Reserpine-induced lesions in Osborne-Mendel rats were influenced by age, sex, and cold exposure during a 7-hour test period. Gastric lesions did not develop in 24-hour-old rats given reserpine at a dose of 20 mg/kg. In 10-day-old rats, small gastric lesions developed in 4 of 30 at a dose of 2 mg/kg and in 13 of 20 at 20 mg/kg. A lesion severity index was used for the 3-week-old, 7-week-old, and 20-week-old groups because of the high incidence of lesions (95-100%). Lesion scores in the 3-week-old group increased with time after reserpine (5-7 hours) and with dose (2-10 mg/kg), but a sex difference or a cold stress difference, which was observed in the 7-week-old and 20-week-old animals, was not seen. Fewer than 1% of controls given saline showed lesions. Seven-week-old male rats had significantly higher ulcer scores than females at 22° for the 7-hour test period at 1, 2, and 3 mg/kg doses of reserpine. Both males and females in this age group had higher ulcer scores at 5° than at 22°. Twenty-week-old males had slightly higher ulcer scores than females at 5, 6, and 7 hours of observation; both sexes showed an enhancement of the reserpine-induced ulcer effect when exposed to 5°. The body temperatures of the 20-week-old animals were followed during the study. Control rats were able to maintain their body temperatures at both 22° and 5°, whereas reserpine-treated rats showed decreased body temperatures at 22° and 5°. The decrease in body temperature was more pronounced at 5° than at 22° in the reserpine-treated rats. © 1969.