# Kamishoyosan Normalizes Dendritic Spine Morphology in the Medial Prefrontal Cortex by Regulating microRNA-18 and Glucocorticoid Receptor Expressions in Postmenopausal Chronic Stress-Exposed Mice

## TL;DR

This study shows that Kamishoyosan, a traditional Japanese medicine, reduces stress effects in postmenopausal mice by normalizing brain cell structures and hormone responses.

## Contribution

The study reveals a novel mechanism by which KSS regulates miR-18 and GR to improve stress-related brain changes in postmenopausal mice.

## Key findings

- KSS reduced stress-induced emotional instability and elevated corticosterone levels in postmenopausal mice.
- KSS downregulated miR-18 and upregulated GR expression in the medial prefrontal cortex.
- KSS restored immature dendritic spine morphology in pyramidal neurons after chronic stress.

## Abstract

Objective: Kamishoyosan (KSS), a traditional Japanese Kampo medicine, is widely used to treat neuropsychiatric symptoms in perimenopausal and postmenopausal women. We aimed to elucidate the functional mechanisms underlying KSS-mediated reduction of stress response behaviors and neuropsychological symptoms in perimenopausal and postmenopausal women.

Methods: Female mice were bilaterally ovariectomized (OVX) at the age of 12 weeks and exposed to chronic water immersion and restraint stress for three weeks. Among them, mice in the OVX+stress+KSS group were fed chow containing KSS from one week before exposure to chronic stress until the end of the experiment. Firstly, we performed a marble burying test and measured serum corticosterone levels to assess irritability and stress conditions. Next, we examined whether KSS affects microRNA-18 (miR-18) and glucocorticoid receptor (GR) protein expression, as well as the basal dendritic spine morphology of pyramidal neurons in the medial prefrontal cortex (mPFC) of postmenopausal chronic stress-exposed mice. Analyzed data were expressed as mean ± standard deviation. Tukey’s post hoc test, followed by analysis of variance (ANOVA), was used for among-group comparisons.

Results: KSS administration normalized chronic stress-induced unstable emotion-like behavior and upregulated plasma corticosterone levels. Furthermore, KSS ameliorated GR protein expression by downregulating miR-18 expression in the mPFC and recovered the immature morphological changes in spine formation of pyramidal neurons in the mPFC of OVX mice following chronic stress exposure.

Conclusions: KSS administration in postmenopausal chronic stress-exposed mice exerted anti-stress effects and improved the basal dendritic spine morphology of pyramidal neurons by regulating miR-18 and glucocorticoid receptor expression in the mPFC.