Abstract
Low-level laser therapy or photobiomodulation is the medical use of a very low intensity light in the red to near infrared (wavelengths in the range of 630-940 nm). The present work was conducted to explore the effects of both UV and low-level laser irradiation (LLLI) on microcirculation using the in vivo model of the chick embryo chorioallantoic membrane (CAM). The effects were assessed by measuring lipid peroxidation and antioxidant enzyme activity. Cell cytotoxicity, survival and intracellular reactive oxygen species (ROS) of the CAM were also evaluated. We found that UV irradiation induced alterations of the vessels, leading to bleeding and extravasation. This effect was intensified after 60 min of exposure to UV irradiation, leading to marked edema. UVA irradiation increased cell cytotoxicity as assessed by lactate dehydrogenase (LDH) release (56.23% of control) and reduced cell viability as assessed by decreased fluorescein diacetate (FDA) fluorescence (56.23% of control). Pretreatment with LLLI prior to UV exposure protected the CAM tissue from UV-mediated cell death. This protective effect was supported by the observation of significantly inhibited lipid peroxidation (from 0.3±0.004 for UV, to 0.177±0.012 after LLLI pretreatment), ROS and O2 -production, as indicated by respective dihydrorhodamine (DHR) and dihydroethidium (DHE) intensities (from 132.78% of control for UVA, to 95.90% of control for L-UV (DHR), and from 127.34% of control for UVA, to 82.03% of control for L-UV (DHE)), and by preventing the increase in oxidative activities. LLLI efficiently protected CAM cells from UV-induced oxidative stress and appeared as a safe protective pretreatment against UV irradiation.
Highlights
The solar radiation reaching the earth’s surface includes wavelengths ranging from 290 nm to 4000 nm and is comprised of UV radiation (UVA, 320-400 nm; UVB, 290-320 nm), visible light (400-700 nm) and infrared radiation (700-940 nm)
UV irradiation induced alterations of the vessels, leading to rapid bleeding and extravasation (Fig. 1B). This effect was intensified after 60 min of exposure to UV irradiation, leading to marked edema (Fig. 1C)
Extravasation induced by 60 min of UV irradiation was abrogated by the level laser irradiation (LLLI) pretreatment (Fig. 1E)
Summary
The solar radiation reaching the earth’s surface includes wavelengths ranging from 290 nm to 4000 nm and is comprised of UV radiation (UVA, 320-400 nm; UVB, 290-320 nm), visible light (400-700 nm) and infrared radiation (700-940 nm). It is commonly accepted that solar UV induces deleterious effects on cells such as photocarcinogenesis and photoaging. UV irradiation from sunlight causes photodamage of the skin, leading to the appearance of wrinkles, laxity, coarseness and mottled pigmentation [1]. It causes histological alterations, including expanded epidermal thickness and changes in connective tissue [2]. The generation of ROS by oxidative pathways leads to these afflictions. For this reason, several anti-oxidative and anti-photoaging
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