Psychosomatic Medicine 32:569-580 (1970)
© 1970 American Psychosomatic Society

Effects of Early Experience and Differential Housing on Susceptibility to Gastric Erosions in Lesion-Susceptible Rats

¹ Department of Psychiatry, University of Rochester School of Medicine and Dentistry, Rochester, NY

Address for reprint requests. R. Ader, PhD, Strong Memorial Hospital, Rochester, NY 14620

A population of lesion-susceptible rats was derived from the mating of control females with males from a selectively bred strain of ulcer-susceptible animals. Litters of lesion-susceptible and control animals were randomly assigned to groups which were handled daily throughout the first or second 3 weeks of life or which remained undisturbed. Half of each subgroup was subsequently housed individually or in groups of 4-5/cage. Emotional reactivity was reduced in group-housed animals relative to those individually housed, and in the individually housed, handled group relative to the nonhandled control population; handling did not influence emotional reactivity in the lesion-susceptible population. These lesion-susceptible animals were more susceptible to gastric erosions and had higher plasma pepsinogen levels than did control animals. There were also ex-perientially determined changes in pepsinogen level, but neither these nor the differences in emotional reactivity were related to lesion susceptibility. There was an interaction between early experience and differential housing in determining lesion susceptibility; among group-housed animals there were no effects from early experience, but among individually housed animals, handling experienced during the first 3 weeks of life decreased susceptibility to gastric erosions in the lesion-susceptible as well as in the control population. It was concluded that early life experiences can modify a genically determined susceptibility to disease.