Colitis causes delay in puberty in female mice out of proportion to changes in leptin and corticosterone

Background: Inflammatory bowel disease that begins prior to puberty frequently causes a delay in puberty resulting in losses of growth, bone mineralization, and selfesteem. A major cause of this pubertal delay is likely due in part to the effect of decreased levels of leptin on the function of the hypothalamic-pituitary-gonadal axis, though systemic inflammation is also thought to play a role. Methods: To investigate further whether low leptin levels alone were responsible for delayed puberty in colitis, we induced colitis in 23-day-old female mice using 3% dextran sodium sulfate (DSS), resulting in 10 days of worsening colitis. These mice were compared to controls that were free-feeding and food-restricted (FR) mice that were given only enough food to keep them the same weight as the DSS group. All groups were followed for the timing of vaginal opening until 33 days old, when they were euthanized and their serum collected. Results DSS-treated mice exhibited later timing of vaginal opening relative to both of the other groups, as well as increased colonic inflammation by cytology and increased serum levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α. The difference in the timing of vaginal opening between the DSS and FR groups occurred despite equivalent serum levels of leptin between the groups and despite an increase in corticosterone in the FR group relative to both of the other groups. Conclusions: We conclude that DSS colitis causes delay in puberty in sexually immature mice beyond what would be expected from decreases in weight and leptin levels.