Nitric oxide is responsible for oxidative skin injury and modulation of cell proliferation after 24 hours of UVB exposures

Nitric oxide (NO) is produced by various mammalian cells and plays a variety of regulatory roles in normal physiology and in pathological processes. This article provides evidence regarding the participation of NO in UVB-induced skin lesions and in the modulation of skin cell proliferation following UVB skin irradiation. Hairless mice were subjected to UVB irradiation for 3 hours and the skin evaluated immediately, 6 and 24 hours postirradiation. The skin lipid peroxidation, and NO levels evaluated by chemiluminescence and inducible nitric oxide synthase (iNOS) and nitrotyrosine immunolabelling increased significantly 24 hours after irradiation and decreased under the treatment with aminoguanidine (AG). On the other hand, cell proliferation markers, PCNA and VEGF showed a strong labelling index when AG was used. The data indicate that NO mediates, at least in part, the lipid peroxidation and protein nitration and also promotes the down regulation of factors involved in cell proliferation. This work shows that the NO plays an important role in the oxidative stress damage and on modulation of cell proliferation pathways in UVB irradiated skin.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - CAPE

DPPH radical scavenging capacity of <i>Arrabidaea chica</i> (AC) extract.

<p>R² = 0.9897.</p

Results of the recovery test for scutellarein and apigenin from the extract of <i>A. chica</i>.

1<p>SD is the standard deviation for each sample (n = 3);</p>2<p>RSD is the relative standard deviation.</p

Repeatability and intermediate precision data for the determination of scutellarein and apigenin by HPLC.

1<p>RSD is the relative standard deviation for each sample (n = 3).</p

Linearity parameters for the calibration curve of scutellarein and apigenin.

<p>r², correlation coefficient.</p

Antioxidant activity of the extract of <i>A. chica</i> on β-carotene-linoleate system.

1<p>SD is the standard deviation for each sample (n = 3).</p>*<p>no significant difference when compared to quercetin (ANOVA test; <i>p</i><0.05).</p