Effects of intense pulsed light and radiofrequency radiation on the content of collagen in BALB/c mouse skin

Objective To investigate the effects of intense pulsed light (IPL) and radiofrequency radiation on the appearance,histopathological manifestation,dermal depth and collagen content in BALB/c mouse skin.Methods The back of BALB/c mice was irradiated with intense pulsed light (IPL group,n =9),radiofrequency (RF group,N =9),IPL and radiofrequency (IPL+RF group,n =9) respectively,for 4 sessions at 1-week intervals followed by 2 sessions at 2-week intervals.Three mice remaining untreated served as the control group.The appearance of skin on the back of mice was observed at different time points after irradiation.Some mice were sacrificed and skin specimens were obtained from the back at week 4,8 and 12 after the first irradiation.Hematoxylin and eosin staining was performed to observe the histopathological manifestation and measure the dermal depth of mouse skin,and Masson staining to detect the expression of collagen fiber in mouse skin.Results No local adverse effects were observed in the back skin of mice after irradiation with IPL or radiofrequency.Since the 8th week after the first irradiation,the dermal layer had appeared to be thickened,with an increase in the content of collagen fiber and extraeellular matrix,in the IPL group,RF group and IPL+ RF group compared witb the control group,and the increase was more obvious in the IPL+RF group than in the IPL group and RF group (all P ＜ 0.05 ).Increased collagen fiber was densely arranged in irradiated mice.There was no apparent thickening of skin epidermis after irradiation.Conclusions Both IPL and radiofrequency can stimulate an increase in dermal collagen production in mice,and a synergistic effect exists between IPL and radiofrequency in the biostimulation of collagen synthesis. Key words: Intense pulsed light; Radio frequency technology; Mice,Inbred BALB C; Collagen