Liuwei Dihuang, a traditional Chinese herbal formula, suppresses chronic inflammation and oxidative stress in obese rats

OBJECTIVE: To investigate the anti-infl ammatory, anti-oxidative stress, and adipokine-ameliorating effects of Liuwei Dihuang(LWDH), a traditional Chinese herbal formula, in obese rats. METHODS: After 2 weeks of acclimation with free access to regular rodent chow and water, obese-prone-caesarean-derived(OP-CD) rats were fed a modified AIN-93 G diet containing 60% energy from fat. Treatment was performed twice daily by gavage feeding with 500, 1 500, or 3 500 mg/kg body weight LWDH suspended in water(n=12 rats per group). Twelve obese-resistant-CD(OR-CD) rats were fed the atherogenic diet and gavaged with water, and served as the normal control. Blood biomarkers of inflammation, oxidative stress and adiponectin were measured post-sacrifi ce and used to determine the treatment effect of LWDH and assess the suitability of OR/OP-CD rats for studying these parameters. RESULTS: After 9 weeks of treatment, LWDH lowered serum C-reactive protein(CRP) and tumour necrosis factor-α(TNF-α) levels. Serum interleukin-6(IL-6) levels showed a tendency towards reduction, but were not signifi cantly different from the OP-CD control. Liver superoxide dismutase(SOD) activity was increased in response to all three doses of LWDH, while the levels of reduced(GSH) and oxidized glutathione(GSSG) and thiobarbituric acid reactive substances(TBARS) were unchanged. Serum adiponectin levels were increased in response to oral administration of LWDH at the dose of either 500 or 1 500 mg/kg body weight. In addition, comparisons between OR-CD and OP-CD rats revealed differential, and for some biomarkers, conflicting characteristics of high-fat diet-fed OP-CD rats in reference to obese human subjects in terms of infl ammatory and oxidative stress biomarkers and circulating adiponectin levels. CONCLUSION: The results show, for the fi rst time, the anti-infl ammatory, anti-oxidative stress and adiponectin-ameliorating effects of LWDH in obese rats. The suitability of the OR/OP-CD rat model as a research tool to study infl ammation, oxidative stress, and adipokine production requires further investigation.