The influence of maternal separation on the development of voiding and behavior in rat pups

Aim:: This study aimed to investigate the effects of early-life stress resulting from maternal separation (MS) on urinary function and behavioral changes. Methods:: We categorized 85 rat pups into control and MS groups. Two groups of each sex during post-weaning (3 weeks old) and maturity (9 weeks old) were compared. Urinary function was evaluated using metabolic cages and continuous cystometry. Morphological changes were assessed based on bladder weight and staining. In behavioral experiments, spatial working memory using the Y-maze and anxiety-like behavior in the elevated plus-maze were assessed. Results:: In the metabolic cage test, the single voiding volume decreased in the 3-week-old male and female MS groups. In continuous cystometry, the intercontraction interval was shortened in the 9-week-old male and female MS groups. MS showed a significant change in bladder weight and wall thickness in 3-week-old females. Conversely, a change in bladder wall thickening was observed in male rats aged 9 weeks. In the Y-maze, no differences were found in alternation. In the elevated plus-maze test, the 3-week-old MS groups of both sexes had fewer entries into the open arm and slower mean velocities, while the 9-week-old groups had a greater number of entries into the open arm and a faster average speed. Conclusion:: MS affects voiding behavior and bladder activity during the early phase of maturation. After growth, bladder overactivity and less anxiety-like hyperactivity co-exist, suggesting that early-life stress due to MS may have lasting effects on common neural circuits related to urinary function and behavior