THE TIMING OF WEANING ALTERS THE VULNERABILITY TO STRESS-INDUCED GASTRIC EROSION IN ADULT RATS

Background - Weaning is an important period of life and its timing may influence the resilence for later stress. One of the most important stress-related disorder is gastric ulceration Purpose and methods - Therefore we aimed to investigate the sensitivity of gastric mucosa to cold (at 16 degrees C) water immersion stress (WIS for 3h) in adult (75-day-old) female and male rats after weaning them at different timepoints (at 17, 21, 30, 36 or 42 postnatal days). The connection with stress was studied by comparing control groups to those underwent WIS at the time of weaning and measuring corticosterone levels at the time of collecting the stomach samples. Results - The timing of weaning has strong impact on all studied parameters. Stress-induced erosion development was the smallest in rats weaned at 36-day independently from preconditioning with WIS at weaning, or sex, despite a clear sex-effect on blood corticosterone levels and body weight. WIS at weaning influenced only the body weight in adult rats weaned at 30-day, being higher in stressed than in control groups. There was no clear overall correlation between erosion area and blood corticosterone measures. Conclusions - Taken together our results confirm that the timing of weaning has long-lasting impact on the resiliance of gastric mucosa to ulcerogenic stressful events. In rats the postnatal day 30-36 seems to be optimal for weaning in both sexes as both earlier and later weaning increased vulnerability. Females seems to be more vulnerable to the effect of weaning than males.