Effects of Long-Term Estrogen Treatment on Micturition Behavior and the Sensory Neurons of the Urinary Bladder in Old Female Rats

Abstract

Objectives: The aim of this study was to examine the effect of estrogen treatment on the micturition characteristics and sensory neurons of the bladder in old female rats. Methods: Thirteen-month-old female Wistar rats were divided into two groups: a control group and a group treated with estradiol for 12 weeks. After the treatment, we investigated the changes of micturition behavior under the condition of polyuria, and the immunoreactivity of P2X₃, calcitonin gene-related peptide, and substance P in the dorsal root ganglia (L₁–L₂, L₆–S₁). Results: Our data showed that estrogen induced a significant increase in maximum micturition volume and average micturition volume in the estrogen-treated rats. On the other hand, there was no significant difference in the proportion of the immunoreactivity of P2X₃, calcitonin gene-related peptide, and substance P between the two groups. Conclusions: Although it is known that estrogen facilitates an increase in the nerve’s regenerative response, the present study reveals no significant change in the sensory neurons. However, the increase in micturition volume indicated that long-term estrogen treatment is beneficial for the improvement of the storage problems of the micturition cycle.