The Effect of Magnolia Bark on the Metabolic Inflammation and Insulin Resistance of ob/ob Mice

Abstract

This study was undertaken to investigate how magnolia bark extract affects ob/ob mouse in terms of metabolic inflammation and insulin resistance.Methods: Leptin-deficient ob/ob mice were divided into 2 groups (n=5): a normal saline treatment (=control) and magnolia bark treatment. Wild type mice were the lean group (n=5). After 5 weeks, we measured fasting blood sugar (FBS) and conducted oral glucose tolerance tests (OGTTs) in each group. After 6 weeks, we measured body weight, epididymal fat pad weight, liver weight, serum glucose, serum insulin, and gene expression of tumor necrosis factor-α, interferon-γ, and interleukin-6. We characterized the phenotype of adipose tissue macrophages (ATMs) and analyzed fractions of the phenotype in each group by flow cytometry.Results: In the magnolia bark group, fasting blood sugar, oral glucose tolerance levels, and insulin resistance (HOMA-IR) were significantly decreased. The population and proportion of ATMs among leukocytes in adipose tissue were significantly decreased in the magnolia bark group. The population and proportion of M1 type ATMs among ATMs were significantly decreased in the magnolia bark group. Gene expression of tumor necrosis factor-α was significantly decreased in the magnolia bark group.Conclusions: These results support a positive effect of magnolia bark on metabolic diseases such as insulin resistance and metabolic inflammation in leptin-deficient ob/ob mice.