Effect of UVA irradiation on proliferation and NO/iNOS system of human skin fibroblast.
OBJECTIVE
To investigate the effect of different dosages of ultraviolet A (UVA) on the proliferation and inducible nitric oxide synthase (iNOS)/nitric oxide (NO) system of human skin fibroblasts and to study the mechanism of skin photoaging.


METHODS
Fibroblasts from normal skin cultured in vitro were irradiated with 1, 5, and 10 J/cm(2) of UVA, respectively. The proliferation activity, expression of iNOS mRNA/protein and NO production of human skin fibroblasts at different time points after irradiation of different dosages of UVA were measured by MTT assay, RT-PCR, Western blotting, and Griess reaction, respectively.


RESULTS
The survival rate of normal fibroblasts with time increase during 72 h. Low level of iNOS mRNA/protein expression and NO production was detected in normal human skin fibroblasts. But at each time point after 5 and 10 J/cm(2) dosage of UVA, the decrease of cell survival rate and the increase of iNOS mRNA/protein expression and NO production became more significant than those in the control group at the same time and 1 J/cm(2) UVA-irradiated group. There were significant differences (P<0.01 or P<0.05), which were most significant at 24 h after UVA irradiation. There was significant difference compared with that at 48 h and 72 h after the same UVA dosage (P<0.01).


CONCLUSIONS
UVA can inhibit the proliferation activity of human skin fibroblasts. It might be related to the up-regulation of iNOS gene expression and the over-secretion of NO induced by UVA.
Chen
Mingliang
M
Department of Dermatology, Xiangya Hospital, Central South University, Changsha 410008, China.
Zhang
Guiying
G
Yi
Mei
M
Chen
Xiao
X
Li
Ji
J
Xie
Hongfu
H
Chen
Xiang
X
D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000166:cytology* / Q000378:metabolism; D015595:Skin Aging / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D012333:RNA, Messenger; D009569:Nitric Oxide; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II