Influence Of Different Incipient Dose Of Narrow-Band Ultraviolet Irradiate On The Mouse Tail's Epidermis

Objectives: In order to explore the optimal and minimal curative dose of narrow-band ultraviolet and provide a reliable theoretical evidence for clinical therapy,we observe the change of epidermic cells on mice's tails radiated by narrow-band ultraviolet of different dose.Methods: Ninety mice were randomly assigned to 9 groups(1 control group and 8 experimental group) with ten in each.Depilated tails with 8% sodium sulfide one day before irradiation .The mice in the experimental groups(group 1 to 8) received ultraviolet radiation on tails three times per week for 2s, 4s, 6s, 8s, 10s, 12s, 14s, 16s respectively every time and the corresponding irradiation dose were 90J/m2, 180J/m2, 270J/m2, 360J/m2, 450J/m2, 540J/m2, 630J/m2, 720J/m2 every time.The exposure time was prolong by 1s (The corresponding dose increasement is 45J/m2) every week.The mice in control group didn't receive ultraviolet or sunbeam irradiation. Sixty days later,we collected the skin specimen on mice tails ,measured the epidermic thickness and granular layer quantity after HE stain.The data were statistical analyzed using one-way analysis of variance.Results: Comparing with the control group,the granular layer count increased significantly in all experimental groups after ultraviolet radiation. There were statistical significance between NB-UVB experimental group1 and other experimental groups (P < 0.05) .The granular layer count showed no statistical difference between NB-UVB group 2 and 3 (P > 0.05),but significantly different between NB-UVB group 2 and group 4, 5, 6, 7(P < 0.05). There were no statistical significance among NB-UVB group3, 4, 5, 6 and 7 (P>0.05) .The epidermis of mice tail in all experimental groups thickened significantly than the control group(P<0.01).There were no statistical significance among NB-UVB group 1, 2, and 3 (P > 0.05) .Also no statistical significance among NB-UVB group 4, 5, 6 and 7 (P > 0.05) .But the epidermis thickness showed statistical difference between NB-UVBgroup 1, 2, 3 and 4, 5, 6, 7).Conclusions: When the incipient dose of NB-UVB ≧ 720J/m~2 ,we can finderythema and blister on the skin of the mouse,we set this dose is the minimal erythematous dose (MED) of the mouse;the experimental result indicate that when the incipient dose of NB-UVB under the MED,there will be more granular layers on the epidermis of the mouse's tails of the NB-UVB's groups ,this indicate that the NB-UVB can induce the keratinocyte to the normal cuticularization; the thickness of the epidermis indicate that there is side effect of the NB-UVB, photoaging may be the side effect and make the epidermis thickness; aggregate analysis each data and association with the clinical cases,we think the best incipient dose of NB-UVB in the clinical is 40%-50%MED.