Comparison of UVA vs UVB Photoaging Rat Models in Short-term Exposure.

Background: Prolonged exposure to sunlight is known to induce photoaging of the skin, leading to various skin changes and disorders, such as dryness, wrinkles, irregular pigmentation, and even cancer. Ultraviolet A (UVA) and ultraviolet B (UVB) radiation are particularly responsible for causing photoaging. Objective: This study aims to identify and compare photoaging rat models exposed to UVA and UVB. Methods: This research method compared macroscopic (scoring degree of wrinkling) and microscopic (histology) signs and symptoms on skin samples of rat exposed to UVA and UVB for 4 weeks at a radiation dose of 840mJ/cm2. Results: The results of this study indicated that the degree of wrinkling was highest in rat skin exposed to UVB rays by 51% (p<0.05). UVB histological results showed that the epidermis layer (40 µm, p<0.05) was thickened and the dermis layer (283 µm, p<0.05) was thinned in the skin of mice exposed to UVB light. The UVB group, showed the density of collagen in the dermis with a mean value of 55% (p<0.05). Conclusion: Our results suggest that short-term exposure to UVB radiation (in the acute, subacute or subchronic phase) induces more rapid and pronounced damage to rat skin when compared to UVA radiation exposure.

The Effects of Eucheuma cottonii on Signaling Pathway Inducing Mucin Synthesis in Rat Lungs Chronically Exposed to Particulate Matter 10 (PM10) Coal Dust.

This study was aimed at investigating the effects of Eucheuma cottonii (EC) in oxidative stress and the signaling for mucin synthesis in rat lungs chronically exposed to coal dust. Coal dust with concomitant oral administration of ethanolic extract of EC at doses of 150 (EC150) or 300 mg/kg BW (EC300) compared to exposed to PM10 coal dust at doses of 6.25 (CD6.25), 12.5 (CD12.5), or 25 mg/m(3) (CD25) (an hour daily for 6 months) and nonexposure group (control). The malondialdehyde (MDA), epidermal growth factor (EGF), transforming growth factor (TGF)- α , epidermal growth factor receptor (EGFR), and MUC5AC levels were determined in the lung. The administration of EC300 significantly (p < 0.05) reduced the MDA levels in groups exposed to all doses of coal dust compared to the respective coal dust-exposed nonsupplemented groups. Although not statistically significant,EC reduced the EGF levels and EGFR expressions in CD12.5 and CD25 groups and decreased the TGF- α , level and MUC5AC expression in CD25 group compared to the respective coal dust-exposed nonsupplemented groups. EC was able to decrease oxidative stress and was also able to decrease signaling for mucin synthesis, at least a part, via reducing the ligand in chronic coal dust exposure.