Effect of botulinum toxin type A injection on the expression of substance P, TGF-β1 and α-SMA in rabbit ear model of hypertrophic scar

Abstract

Objective To investigate the effect of botulinum toxin type A injection on the expres-sion of substance P, TGF-β1 and α-SMA in rabbit ear model of hypertrophic scar. Methods The hyper-trophic sear model was established in 24 Japanese rabbits'ears. The wounds in ventral surface of ear were divided in Group I (lateral wounds) and Group S (medial wounds), 3 wounds each side per ear, totally 72 wounds each group. The wound-healing time and the growth of scar were observed and recorded. On post-wounding day 28, the wounds were created in another 6 rabbits in the same way and the normal skin were harvested as Group C. Likewise, the scar samples in Groups I and S were harvested. The mRNA expression of substance P, TGF-β1 and α-SMA were detected quantitatively by using real-time PCR and α-SMA was also detected with Western blot. Results No difference between the ratio of healed or infec-tious wounds on post-wounding day 14. The mRNA expression of SP, TGF-β1 and α-SMA in Group I was significantly lower than Group S, but higher than those in Group C (P<0. 01 and <0. 05, respec-tively). The blot density of α-SMA and the ratio of blot density of a-SMA to β-actin in Group I were be-tween that of the other two groups. Conclusion Without delaying the wound-healing, botulinum toxin type A injection significantly decreases the expression of SP, TGF-β1 and α-SMA in rabbit ear model of hypertrophic scar. Key words: Botulinum toxin type A; Hypertrophic scar; Substance P; Transforming growth factor beta-1; Alpha smooth music actin A