Paeoniflorin, a constituent of Kami-shoyo-san, suppresses blood glucose levels in postmenopausal diabetic mice by promoting the secretion of estradiol from adipocytes

Ovarian functional deterioration in women with climacteric disorders increases the prevalence of type 2 diabetes (T2D). Therefore, we revealed that paeoniflorin (PF), an ingredient of paeony root (PR), which is a constituent of Kami-shoyo-san (KS), promotes glucose uptake by increasing estradiol secretion from adipocytes. Adipocytes differentiated from 3T3-L1 cells were incubated in culture medium containing the extracts of KS, PR, KS excluding PR (KS-PR), or PF for 5 d at 37 °C and 5% CO(2). The estradiol and glucose concentrations in the medium were determined using enzyme-linked immunosorbent assay (ELISA). Next, PF (1 or 10 mg/kg) was subcutaneously injected into ovariectomized mice (12-week-old, ICR strain) once daily for 19 d to perform the glucose tolerance test and determine blood estradiol and adiponectin levels. The release of estradiol from 3T3-L1 adipocytes was significantly increased by KS, PR, KS-PR, and PF, and the increased estradiol level caused by KS was significantly decreased by excluding PF from KS (KS-PR). Glucose concentration in the medium was significantly decreased by KS and PF. In in vivo experiments, the 10 mg/kg PF-treated group showed significantly suppressed blood glucose levels at 0 and 30 min after d-glucose loading by intraperitoneal injection. These findings indicate that KS, which includes PR-containing PF as the main ingredient, may have the potential to prevent T2D caused by ovarian dysfunction in menopausal women by increasing estradiol secretion from adipocytes.