The Relationship between Cutaneous Wounds Made on Obese Mice or Those with Decreased Body Weight and Serum Leptin Level

Purpose: Not all obese people have hyperglycemia. We wondered about the healing progress in obese people without hyperglycemia. The purpose of this study is to observe the cutaneous wound healing process. Methods: Three-week-old male mice were fed high-fat diets (containing 60% fat) in the diet group, and commercial diets in the control group, ad libitum for 15 weeks. Circle-full-thickness cutaneous wounds were made on the dorsal skin of mice. From day 0 to day 15 after wounding, we analyzed wound healing process. We measured the blood concentration of leptin, and observed the distribution of leptin-positive cells in each wound. Results: Mean body weight, the areas of subcutaneous fat and visceral fat, and the weight of epididymal fat in the diet group were significantly greater than those in the control group at 15 weeks after feeding. The diet group did not feed on the diet after wounding;their body weight decreased remarkably to the level of the control group. The ratio of wound area, re-epithelialization, and collagen fibers did not differ between the diet and control groups on each day. The blood concentration of leptin in the diet group was significantly greater than that in the control group before wounding and until day 6 after wounding (day 0, 10 hour and day 1: p < 0.01, day 6: p < 0.05). Conclusion: The results show that the wound healing process is similar between obese and non-obese mice, and that the decrease in the leptin level in the obese mouse to that in the non-obese mouse may depend on the decrease of body weight of obese mouse.

Does Obesity without Hyperglycemia Delay Wound Healing in an Obese Mouse Model Induced by a High-Fat Diet?

It was unclear that wound healing was delayed in obesity without hyperglycemia. The purpose of this study was to compare the wound healing process between obese and non-obese mice without hyperglycemia by attaching a splint. Three-week-old male mice (C57BL/6N) were fed high-fat diets (60% of calories from fat) in the obesity group, and commercial diets in the control group for 15 weeks. Two circular (4 mm in diameter) full-thickness wounds were made on the dorsal skin. Body weights and serum leptin levels were significantly higher in the obesity group than in the control group until day 15 after wounding. Fasting blood glucose levels before wounding were lower in the obesity group than in a hyperglycemic rodent model. The macrophage infiltration into subcutaneous fat before wounding in the obesity group was negligible. The ratios of the wound area were not significantly different between the two groups. No significant differences were observed in the number of neutrophils or macrophages or new blood vessels and ratio of myofibroblasts or collagen fibers between the two groups. Our results demonstrated that cutaneous wound healing was not delayed in the obesity group without hyperglycemia and macrophage infiltration into the subcutaneous fat and with high serum leptin levels.