[The effects of aloe extract on nitric oxide and endothelin levels in deep-partial thickness burn wound tissue in rat]

Abstract

Objective: To investigate the effects of polysaccharide extracted from Aloe barbadensis and Aloe barbedensis containing gel on tissue water contents, nitric oxide (NO) and endothelin (ET) levels in wounds of burned rats.

Methods: Four areas of deep-partial thickness burn wounds with 3 cm in diameter were made on each back of 42 male Wistar rats. Single layer gauze impregnated either with 5% (W/W) aloe raw polysaccharide, 10% (W/W) aloe gel, 1% (W/W) sulfadiazine pyridine silver cream (SD-Ag), or normal saline was respectively applied on different wounds. According to different medications, the wounds were divided into aloe raw polysaccharide group, aloe gel group, SD-Ag group and normal saline group. Six rats in each group were sacrificed at 4, 12, 24, 48 post-scald hour (PSH) and on 7, 14, 21 post-scald day (PSD), and the full-thickness skin of wound was harvested for the determination of wound tissues water contents, NO and ET levels, and for calculation of NO/ET ratio. Another 6 normal rats served as normal controls.

Results: The water content in the wound tissue in aloe raw polysaccharide group at 12, 24 and 48 PSH [(73.4 +/- 3.8)%, (76.6+/-3.0)%, (70.6+/-3.8)%] and aloe gel group [(74.5+/-2.6)%, (77.1+/-3.6)%, (71.2 +/- 3.1)%] was obviously lower than those in SD-Ag group [(80.1 +/- 4.1)%, (80.5 +/-3.9)%, (76.1 +/-3.8)%, P <0.05]. During 7-21 PSD, all of them returned to the normal level except that in SD-Ag group, as it was still higher than that in normal controls (P < 0.05). The NO content in wound tissue in each group reached the peak at 12 PSH, decreased thereafter, but it was still obviously higher than that of normal controls on 21 PSD (P < 0.05). The ET content in wound tissue of each group reached the peak on 7 or 14 PSD, decreased thereafter, but it was still evidently higher than that in normal controls on 7 or 14 PSD (P < 0.05). The NO content in wound tissue in aloe raw polysaccharide and aloe gel group were markedly lower than those in SD-Ag and normal saline groups at 12 and 24 PSH ( P < 0.05). The NO/ET ratio in each group reached the peak at 12 PSH, decreased thereafter, and it returned to normal value on 14 PSD. On 7 PSD, the NO/ET ratio in aloe gel, SD-Ag and normal saline groups were still significantly higher than that in normal controls, except that returned to normal value in aloe raw polysaccharide group.

Conclusion: Both aloe raw polysaccharide and aloe gel can decrease wound tissue NO release, optimize NO/ET ratio, lighten vascular inflammatory reaction, and lessen permeability and edema.