Early life stress enhances the vulnerability to chronic psychosocial stress and experimental colitis in adult mice.

Early life stress enhances the vulnerability to both mood and chronic inflammatory disorders, suggesting a link between these stress-related disorders. To study this, we exposed male C57BL/6 mice to early life stress [maternal separation (MS), 3 h/d, d 1-14] and to adult chronic psychosocial stress [chronic subordinate colony housing (CSC)] and measured changes in neuroendocrine parameters and in the severity of a chemically induced colitis. In both unseparated and MS mice, 19 d of CSC exposure resulted in a transient decrease in body weight gain, increased anxiety-related behavior, and decreased vasopressin mRNA expression in the hypothalamic paraventricular nucleus compared with respective nonstressed mice. However, only CSC-stressed MS mice showed elevated CRH mRNA expression in the paraventricular nucleus and reduced plasma corticosterone. Subsequent treatment with dextran sulfate sodium (1%, 7 d) resulted in a more severe colonic inflammation in MS compared with unseparated mice. This was indicated by an increased histological damage score and increased TNF secretion (nonstressed MS mice), more severe body weight loss and inflammatory reduction in colon length (CSC-stressed MS mice), and increased interferon-gamma secretion (nonstressed and CSC-stressed MS mice). In conclusion, early life stress and subsequent exposure to chronic psychosocial stress in adulthood induced neuroendocrine abnormalities, which likely contributed to enhanced vulnerability to chemically induced colitis. The combined use of MS and CSC represents a potential animal model providing novel (patho)physiological insights into the complex interactions between neuroendocrine and inflammatory actions upon chronic stress exposure. These findings may further help to reveal mechanisms of hypocortisolemic disorders.