Photobiomodulation (PBM) with green laser light—typically ranging from 505 to 532 nm—has been investigated across a wide array of biological contexts. A literature search on PubMed, ScienceDirect, Medline, and LILACS retrieved 814 studies related to green laser exposure. However, the majority of these studies focused on more invasive or ablative applications, such as photocoagulation in ophthalmology or prostatic tissue ablation. Fewer studies have examined its non-thermal, photobiomodulatory effects at the cellular and mitochondrial levels.
Green Laser and Mitochondrial Complexes
One of the retrieved studies directly evaluated the effects of green laser light on mitochondrial electron transport chain (ETC) activity. In their work, Buravlev et al. (2015) examined how different wavelengths—including 442 nm (blue), 532 nm (green), and 650 nm (red)—influence mitochondrial respiration in the presence of nitric oxide (NO), which is known to inhibit ETC function. They found that while blue light partially restored mitochondrial respiration suppressed by NO, green laser light (532 nm) did not significantly affect the electron transport rate of complexes II–III or IV under the tested conditions. These findings suggest that, unlike shorter blue wavelengths, green light may not directly influence cytochrome c oxidase (Complex IV) or other ETC complexes in the presence of nitric oxide. Nevertheless, other studies have explored green laser effects on mitochondrial-related functions—such as transmembrane potential, ATP production, and oxidative stress indicators—pointing to indirect effects on mitochondrial performance.
Biological Effects and Applications of Green Laser PBM
While direct activation of ETC complexes remains uncertain, a range of studies suggest green laser PBM may modulate cellular behavior and contribute to therapeutic outcomes in various biological systems:
- Skin and Wound Healing: Green laser has shown promise in enhancing wound healing, particularly after procedures like fractional CO₂ laser resurfacing. For example, Gong et al. (2022) found that 532 nm PBM improved collagen remodeling and angiogenesis in treated skin. Other studies observed benefits in scarless healing, cell migration, and skin barrier integrity (Malthiery et al., 2021).
- Stem Cell Modulation: In mesenchymal stem cells, green laser has been reported to stimulate proliferation and downregulate pro-inflammatory genes (Tamimi et al., 2022), as well as influence osteogenic differentiation through intracellular calcium signaling (Wang et al., 2016). However, under some conditions, green light has been shown to inhibit proliferation via TRPV1 activation and ROS increase (Wang et al., 2017).
- Dental and Oral Health: Green laser PBM (532 nm) has been evaluated for dentin hypersensitivity, showing immediate pain relief post-treatment, with effects persisting longer than standard desensitizing agents (Hu et al., 2021). It has also contributed to oral wound healing in diabetic models, though less effectively than red light (Fekrazad et al., 2015).
- Circulatory and Hematologic Effects: Green laser has been shown to influence platelet activation and aggregation (Gressner et al., 2005), alter hematological parameters in vivo (Yaba, 2022), and exert hypolipidemic and hypoglycemic effects when used intravenously in patients with atherosclerosis (Poluèktova et al., 2011).
- Mitochondrial Bioenergetics: Several studies, including Kassàk et al. (2005, 2006), reported increased mitochondrial membrane potential, enhanced oxidative phosphorylation, and Na⁺/K⁺-ATPase activity following 532 nm irradiation. These effects, though not tied to a specific ETC complex, point to enhanced mitochondrial bioenergetic efficiency.
- Oxidative Stress and Inflammation: Green laser has also been observed to influence redox processes and free radical dynamics in models of endotoxic shock (Machneva et al., 2013) and to modulate inflammatory cytokine expression in cell cultures.
- Dermatology and Aesthetic Uses: Clinical studies report that green laser PBM may support body contouring (Suarez et al., 2014) and reduce the appearance of cellulite (Jackson et al., 2013). Compared to red light, green laser was associated with reduced treatment discomfort and potentially longer-lasting benefits in certain dermatological conditions, such as actinic keratosis (Cios et al., 2021).
Conclusion
The current body of research does not establish a clear connection between green laser PBM (505–532 nm) and the direct activation of specific mitochondrial complexes. However, several studies have reported that green light may influence mitochondrial-related functions, including changes in membrane potential, oxidative phosphorylation, and intracellular signaling. Additionally, green laser has shown potential in modulating inflammation, promoting cell proliferation and migration under certain parameters, and contributing to wound healing and aesthetic outcomes. While the evidence suggests promising applications, especially for superficial tissues and skin-related conditions, further investigation is needed to better understand the underlying mechanisms and optimize clinical protocols.
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