工藤 敏之

Ciprofloxacin (CPX), a new quinolone antibiotic, is reported to reduce CYP3A expression in the liver when administered to rats. The present study investigates whether the reduction in intestinal flora is involved in this reduction of CYP3A. While hepatic Cyp3a11 expression and triazolam metabolic activity were significantly reduced by CPX treatment of SPF mice, no significant changes were seen by CPX treatment of germ-free (GF) mice. Lithocholic acid (LCA)-producing bacteria in the feces as well as hepatic level of taurine conjugate of LCA were significantly reduced in CPX-treated SPF mice. Cyp3a11 expression in GF mice was significantly elevated when treated with LCA, known as an activator of fernesoid X receptor and pregnane X receptor. These results indicate that antibiotics such as CPX, having antimicrobial spectrums against LCA-producing bacteria, possibly cause decrease in LCA in the liver, resulting in lower CYP3A expression. The intestinal flora is reported to be altered also by stress, disease and age etc. The findings of the present study suggest that these changes in intestinal flora may modify CYP expression and contribute to individual differences in pharmacokinetics.

Visceral fat accumulation has been reported as the most important risk factor for the development of various metabolic disorders. In this study, the preventive effects of Bofutsushosan, a Japanese Kampo preparation, on obesity and various metabolic disorders were investigated focusing on visceral fat accumulation using Tsumura, Suzuki, Obese, Diabetes (TSOD) mice, which showed significant accumulation of visceral fat, and developed metabolic disorders including glucose intolerance, hyperlipidemia, hypertension and hyperinsulinemia. At 2 months after initiation of the study, the control TSOD mice developed various metabolic disorders such as marked obesity and visceral fat accumulation, increases in the levels of blood glucose, insulin, total-cholesterol (TC) and triglyceride (TG), and abnormal glucose tolerance, hypertension and peripheral neuropathy as distinct from the control Tsumura, Suzuki, Non-Obesity (TSNO) mice, which do not develop obesity and various metabolic disorders. In the TSOD mice treated with Bofutsushosan, body weight gain and visceral/subcutaneous fat accumulation were significantly suppressed. Biochemical parameters in plasma (glucose, TC, insulin and tumor necrosis factor-alpha (TNF-alpha) level) were significantly suppressed, and abnormal glucose tolerance, elevation of blood pressure and peripheral neuropathy accompanying progression of metabolic disorders were also significantly suppressed. On the other hand, in TSNO mice, Bofutsushosan showed no noteworthy impacts on most parameters except for an improvement of the lipid plasma level. The above results suggested that Bofutsushosan could be effective in preventing obesity and various metabolic disorders.