[Expression of beta-endorphin in hypertrophic scar and its relationship with pruritus]

To identify the effect of beta-endorphin in the development of paresthesia in hypertrophic scar by detecting the expression and content of beta-endorphin in human normal skin and hypertrophic scar.

Hypertrophic scar samples were collected from 42 patients with hypertrophic scar for 1-20 years (mean, 4.5 years), including 15 males and 27 females with an average age of 32.6 years (range, 16-50 years). According to the kind of paresthesia, they were divided into 3 gourps: non-pain-pruritus group (n=20), pruritus group (n=14), and pain-pruritus group (n=8). Normal skin samples (normal skin group) were harvested from 5 patients undergoing skin grafting surgery, including 3 males and 2 females with an average age of 24.6 years (range, 15-37 years). The immunofluorescence method was used to observe the expression of beta-endorphin and ELISA method to detect the concentrations of beta-endorphin in the tissues.

The beta-endorphin expressed in all samples, and it expressed around peripheral nerve fibers in the dermis, fibroblasts, and monocytoid cells principally; and it expressed significantly stronger in pruritus group and pain-pruritus group than in non-pain-pruritus group and normal skin group. The beta-endorphin content was (617.401 +/- 97.518) pg/mL in non-pain-pruritus group, (739.543 +/- 94.149) pg/mL in pruritus group, (623.294 +/- 149.613) pg/mL in pain-pruritus group, and (319.734 +/- 85.301) pg/mL in normal skin group; it was significantly higher in non-pain-pruritus group, pruritus group, and pain-pruritus group than in normal skin group (P < 0.05); it was significantly higher in pruritus group than in non-pain-pruritus group and pain-pruritus group (P < 0.05); and there was no significant difference between non-pain-pruritus group and pain-pruritus group (P > 0.05).

The expression of beta-endorphin is high in hypertrophic scar, it may play an important role in process of pruritus in these patients.