A Kampo formula, saikokaryukotsuboreito, improves serum testosterone levels of castrated mice and its possible mechanism

Abstract

The term “late-onset hypogonadism (LOH)” is recommended to express the symptoms in middle-aged males with decreased testosterone. Although androgen replacement therapy (ART) might be an effective way to manage LOH, the risk of testosterone supplementation in elderly men is still concerned. On the other hand, to avoid adverse effects of ART, Kampo medicine (traditional Chinese–Japanese medicine) is often a first choice to treat LOH in Japan. However, their pharmacological studies are few. In this study, castrated mice was used as an LOH animal model for examining the pharmacological effects of a Kampo formula, saikokaryukotsuboreito (shortly SKRBT) on serum testosterone levels and seminal vesicles weights. Furthermore, an attempt to elucidate its pharmacological mechanism, inhibition of SKRBT and its components against aromatase were also examined with the enzyme-based assay. As a result, SKRBT improved significantly both the decline of serum testosterone levels and decrease of seminal vesicles weight of castrated mice at a dose of 125 mg/kg with a non dose-dependent manner. SKRBT and two components Scutellariae radix and Rhei rhizoma exhibited inhibitory activities with the IC₅₀ values of 145, 29.2 and 29.7 µg/ml, respectively. These results suggested that the aromatase inhibitory activity of SKRBT may contribute, to a different extent, to the improvement of serum testosterone levels.

• Andropause
• aromatase inhibition
• castrated mice
• late-onset hypogonadism
• male climacteric
• saikokaryukotsuboreito (Chai-Hu-Chia-Lung-Ku-Mu-Li-Tang)
• testosterone

Notice of Correction

This paper published online on 22 January 2013 contained an error in Figure 1. In Figure 1A, the unit label of the y-axis and the bar representing T.P. were incorrect. The unit labels of the y-axis were changed, the SD of each bar has been corrected and the symbol of significance on the control bar has been removed. Figure 1A has been replaced with the corrected graph for this version.