Protective effect of nondenatured type 2 collagen on degenerative bone disease in aging db/db mice

  Objective  To explore the effect and mechanism of undenatured typeⅡcollogen (UCⅡ) on degenerative bone disease in aging db/db mice.

  Methods  Db/db mice (15 for each group) with lifetime feeding were randomly assigned into an aging model group (without treatment), UCⅡ treatment group (6 mg/kg UCⅡin drinking water), and positive control group (180 mg/kg chondroitin sulfate and 225 mg/kg glucosamine in drinking water) and the treatments were carried out when the mice being 50 weeks old and continued for 16 weeks; a normal control group (15 db/m mice) and a young control group (15 Db/db mice of 25-week old at the end of experiment) were also established. By the end of the treatments, all the mice′s blood glucose, bone histomorphometry index, inflammation index, as well as matrix metalloproteinase (MMP) were determined.

  Results  The fasting blood glucose of UC Ⅱ-treated mice was significantly lower than that of aging mice and young control mice (both P < 0.05). The bone mineral density (BMD) of the mice in UC Ⅱtreatment group (439.11 mg/cm³) was significantly higher than those in the aging model group (164.20 mg/cm³), the normal control group (209.74 mg/cm³) and the positive control group (294.42 mg/cm³) (all P < 0.05). Significantly increased in the percent of trabecular area and trabecular number were detected in the mice with UC Ⅱ treatment in contrast to the aging model mice (both P < 0.05) and significantly subdued trabecular separation was observed in the mice treated with UCⅡ in comparison with that in the aging model and young control mice (both P < 0.05). The serum interleukin 1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in UCⅡtreated mice was significantly lower than those in the aging model mice (both P < 0.05). The UC Ⅱtreated mice had significantly lower serum MMP-1 compared to aging model mice and lower serum MMP-3 compared to aging model, young control, and positive control mice (P < 0.05 for all).

  Conclusion  Undenatured typeⅡcollogen could improve blood sugar level, increase BMD, and alleviate osteoporosis and osteoarthritis in aging db/db mice; these effects may be related to the alleviation of inflammatory responses and the reduction of serum MMPs.