Methylene blue toxicity in zebrafish cell line is dependent on light exposure

Abstract

Methylene blue (MB) has been widely applied in the clinical area and is currently being used in aquaculture as biocide. Some recent studies have emphasized the importance of understanding the action mechanism and the MB cellular targets. In this sense, zebrafish is considered a relevant model to study the intrinsic pathway of apoptosis as well as the cellular responses involving DNA damage and repair. So, the aim of the present study was to compare MB action mechanisms in a zebrafish cell line, both in the absence (MB alone; dark toxicity) and in the presence of photosynthetically active radiation (MB+PAR; phototoxicity). There was a significant increase of the levels of reactive oxygen and nitrogen species 3 h after MB treatment, whereas this increase was only observed 12 h after treatment with MB+PAR. All treatments with MB resulted in an increase in DNA damage after 3 and 6 h. However, cell death by apoptosis was observed from 6 h after treatment with MB+PAR and 12 h after treatment with MB alone. The expression of genes related to apoptosis was altered after MB and MB+PAR treatment. Therefore, this zebrafish cell line is sensitive to the photodynamic action of MB; MB is able to generate DNA damage and induce apoptosis in this cell line both alone and in the presence of PAR. However, the pathways leading to apoptosis in this model appear to be dependent on the type of MB exposure (in the presence or absence of PAR).

Methylene blue elicits non-genotoxic H₂O₂ production and protects brain mitochondria from rotenone toxicity

“…MB has caused a significant mtDNA damage when used as a photosensitizer. It is well known that, when combined with the light, MB produces singlet oxygen and it is therefore classified as a type II photosensitizer (Costa et al, 2016). Singlet oxygen causes a variety of mtDNA lesions in all fragments, which is shown in this study (Fig.…”

Nanometer Resolution Mass Spectro-Microtomography for In-Depth Anatomical Profiling of Single Cells

“…Presently, the target of MB drug is still under debate . The drug actions on mitochondria, lysosomes, or nuclei have all been proposed. , Typically, due to its positive charge and planar geometry, MB could intercalate with DNA structure to damage DNA and, in turn, induce a series of molecular damages. − Herein, the 3D mass profiling directly proved from the molecular level that the MB drug has a significant effect on the nucleus, despite a predominant distribution of MB in the cytoplasm having been observed (Figure d,e). From Figure f, the location of ions at m / z 76.1 was mainly in the nucleus, and a little number of ions at m / z 116.1 and m / z 166.2 were also located in the nucleus for the control cell.…”

In vitro and in vivo phototoxicity on gastric mucosa induced by methylene blue

“…Although MB is considered non-toxic to humans, questions about its potential harmfulness as a cytotoxic agent have been repeatedly raised, especially when MB is used in combination with light irradiation. [ 10 11 12 13 14 15 ] It is thought that current endoscopic procedures for chromoendoscopy using less than 0.5% MB are safe when used for the diagnosis of gastrointestinal diseases, because the amount of light energy emitted from the endoscopic light source is low. [ 7 ] However, there have been several reports on the in vitro or in vivo phototoxicity of MB to premalignant lesions in normal intestinal tissue.…”

“…MB is regarded as a kind of carcinogen because MB can integrate into intracellular DNA leading to human DNA damage in spite of clinically non-toxic or safe usage. [ 10 11 12 13 14 15 ]…”