# Prevention of Osteoporosis in SAMP6 Mice by Rikkunshi-To: Japanese Kampo Medicine

## TL;DR

This study shows that Rikkunshi-To, a Japanese herbal medicine, can help prevent osteoporosis in a mouse model by maintaining bone density over time.

## Contribution

The study introduces a new method for evaluating osteoporosis using continuous X-ray imaging and demonstrates RKT's preventive effects in a mouse model.

## Key findings

- RKT-fed SAMP6 mice maintained a stable C/F index over time, unlike control mice.
- Discontinuing RKT led to a sudden drop in the C/F index, indicating its preventive role.
- The X-ray method effectively tracked continuous bone mass changes in mice.

## Abstract

Osteoporosis can increase the risk of fracture in elderly patients, and insufficient control affects quality of life. Rikkunshi-To (RKT) has been prescribed for elderly patients to improve gastrointestinal function. We postulated that RKT has preventive potential for the development of osteoporosis. Thus, we developed a simple method to evaluate osteoporosis using a continuous series of X-ray images of femurs in mice, and investigated the effects of RKT on the development of osteoporosis in these mice. Male senescence-accelerated mouse strain P6 (SAMP6) mice, a model of senile osteoporosis in humans, were fed diets with or without RKT (1%). We collected X-ray images of the whole body of each mouse weekly and measured the ratio of cortical thickness of the femur (C/F index). The C/F index in SAMP6 mice fed the normal diet was increased between 50 and 80 days old, but it was significantly decreased after 120 days old. On the other hand, the C/F index in SAMP6 mice fed the RKT diet was increased between 50 and 80 days old; however, it remained unchanged throughout the experimental period. We also confirmed that the C/F index in SAMP6 mice fed the RKT diet suddenly decreased on the replacement of the RKT diet with a normal diet, suggesting that we can collect data related to a series of continuous changes in bone mass, and that RKT is useful for the prevention of osteoporosis.