[Effect of topical external administration of recombinant human epidermal growth factor on expression of epidermal growth factor receptor and its mRNA in scald wound of diabetes mellitus rat].

OBJECTIVE

To investigate the effect of topical external administration of recombinant human epidermal growth factor (rhEGF) when controlling blood sugar on expression of epidermal growth factor receptor (EGFR) and EGFR mRNA of wound in diabetes mellitus (DM) combined with scald.

METHODS

A total of 136 male Wistar rats weighing (188.57 +/- 6.59) g were randomly divided into 4 groups (groups A, B, C, and D, n=34). The rats was made DM model by intraperitoneal injected 60 mg/kg streptozocin in groups A, B, and C; rats were injected buffer alone in group D as control group. After 8 weeks, the rats of 4 groups were placed in 80 degrees C hot water for 6 seconds for preparation of the back deep II degree scald model. In group A, the blood sugar level was controlled at the level of group D 1 week before scald model; within 24 hours after models preparation, rhEGF was sprayed on wound at 150 U/cm2. In group B, the rats were given the same treatment as group A except not controlling blood sugar. In group C, the blood sugar was controlled as group A and wound was suture fixation with 1% silver sulfadiazine cream at 24 hours after the model. In group D, the same treatment as group A was given after injury. The healing rate of the wound was detected at 3, 7, 11, 15, and 21 days after injury; the EGFR mRNA expression was determined by mRNA hybridization in situ, and the EGFR protein expression was determined by immunohistochemistry and Western blot at 1, 3, 5, 7, 11, 15, and 21 days.

RESULTS

All the rats survived at the end of experiment. There was no significant difference in the healing rate of the wound among the 4 groups at 3 days (P > 0.05). The healing rate of the wound was significantly higher in groups A and D than in groups B and C (P < 0.05) at 7, 11, 15, and 21 days. The expression of EGFR mRNA in 4 groups was observed by hybridization in situ, which mainly distributed in the dermal fibroblasts, capillary endothelial cells and remnants of skin and wound edge epithelium of the subsidiary; the expressions reached the peak at 5 days in group A, at 7 days in groups B and C, and at 11 days in group D; and the peak level was significantly higher in groups A and D than in groups B and C (P < 0.05). Immunohistochemistry and Western blot showed that the expression of EGFR protein was observed in 4 groups and reached the peak level at 7 days in groups A and B, and at 11 days in groups C and D; showing significant difference between groups B, C and groups A, D (P < 0.05).

CONCLUSION

External application of rhEGF when controlling blood sugar can accelerate obviously the wound healing in DM combined with scald. After controlling blood sugar, external application of rhEGF can boost obviously the expressions of EGFR mRNA, EGFR, and the extending process of signal conduction.