Triclosan Impairs Hippocampal Synaptic Plasticity and Spatial Memory in Male Rats

Conceptualizing the Role of the Microbiome as a Mediator and Modifier in Environmental Health Studies: A Scoping Review of Studies of Triclosan and the Microbiome

PURPOSE OF REVIEW

Triclosan is an endocrine-disrupting antimicrobial additive that is suspected of contributing to antibiotic resistance and altering the microbiome. In this scoping review, we summarize what is known about the association between triclosan exposure and the microbiome using evidence from in vivo and epidemiologic studies.

RECENT FINDINGS

Our review includes 11 rodent studies, seven fish studies, and five human studies. Evidence from animal studies suggests that triclosan decreases the diversity of the microbiome, although only one epidemiologic study agreed. Most studies suggest that triclosan alters the microbial community beta diversity, but disagree on which taxa contributed to compositional differences. Taxa in the Bacteroidetes, Firmicutes, and Proteobacteria may be more influenced by triclosan than those in other phyla. Studies on triclosan and the microbiome were scarce and were inconclusive as to the effects of triclosan on the microbiome. Additional research is needed to clarify windows of heightened susceptibility of the microbiome to triclosan. We recommend guidelines for future microbiome research in environmental health to increase comparability across studies.

Early-Life Exposure to a Mixture of Phenols and Phthalates in Relation to Child Social Behavior: Applying an Evidence-Based Prioritization to a Cohort with Improved Exposure Assessment

BACKGROUND

Previous studies aiming at relating exposure to phenols and phthalates with child social behavior characterized exposure using one or a few spot urine samples, resulting in substantial exposure misclassification. Moreover, early infancy exposure was rarely studied.

OBJECTIVES

We aimed to examine the associations of phthalates and phenols with child social behavior in a cohort with improved exposure assessment and to a priori identify the chemicals supported by a higher weight of evidence.

METHODS

Among 406 mother-child pairs from the French Assessment of Air Pollution exposure during Pregnancy and Effect on Health (SEPAGES) cohort, 25 phenols/phthalate metabolites were measured in within-subject pools of repeated urine samples collected at the second and third pregnancy trimesters (∼ 21 samples/trimester) and at 2 months and 1-year of age (∼ 7 samples/period). Social behavior was parent-reported at 3 years of age of the child using the Social Responsiveness Scale (SRS). A structured literature review of the animal and human evidence was performed to prioritize the measured phthalates/phenols based on their likelihood to affect social behavior. Both adjusted linear regression and Bayesian Weighted Quantile Sum (BWQS) regression models were fitted. False discovery rate (FDR) correction was applied only to nonprioritized chemicals.

RESULTS

Prioritized compounds included bisphenol A, bisphenol S, triclosan (TCS), diethyl-hexyl phthalate (Σ DEHP ), mono-ethyl phthalate (MEP), mono-n -butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP). With the exception of bisphenols, which showed a mixed pattern of positive and negative associations in pregnant mothers and neonates, few prenatal associations were observed. Most associations were observed with prioritized chemicals measured in 1-y-old infants: Each doubling in urinary TCS (β = 0.78 ; 95% CI: 0.00, 1.55) and MEP (β = 0.92 ; 95% CI: - 0.11 , 1.96) concentrations were associated with worse total SRS scores, whereas MnBP and Σ DEHP were associated with worse Social Awareness (β = 0.25 ; 95% CI: 0.01, 0.50) and Social Communication (β = 0.43 ; 95% CI: - 0.02 , 0.89) scores, respectively. BWQS also suggested worse total SRS [Beta  1 = 1.38 ; 95% credible interval (CrI): - 0.18 , 2.97], Social Awareness (Beta  1 = 0.37 ; 95% CrI: 0.06, 0.70), and Social Communication (Beta  1 = 0.91 ; 95% CrI: 0.31, 1.53) scores per quartile increase in the mixture of prioritized compounds assessed in 1-y-old infants. The few associations observed with nonprioritized chemicals did not remain after FDR correction, with the exception of benzophenone-3 exposure in 1-y-old infants, which was suggestively associated with worse Social Communication scores (corrected p = 0.07 ).

DISCUSSION

The literature search allowed us to adapt our statistical analysis according to the weight of evidence and create a corpus of experimental and epidemiological knowledge to better interpret our findings. Early infancy appears to be a sensitive exposure window that should be further investigated. https://doi.org/10.1289/EHP11798.

Triclosan and related compounds in the environment: Recent updates on sources, fates, distribution, analytical extraction, analysis, and removal techniques

Triclosan (TCS) has been widely used in daily life because of its broad-spectrum antibacterial activities. The residue of TCS and related compounds in the environment is one of the critical environmental safety problems, and the pandemic of COVID-19 aggravates the accumulation of TCS and related compounds in the environment. Therefore, detecting TCS and related compound residues in the environment is of great significance to human health and environmental safety. The distribution of TCS and related compounds are slightly different worldwide, and the removal methods also have advantages and disadvantages. This paper summarized the research progress on the source, distribution, degradation, analytical extraction, detection, and removal techniques of TCS and related compounds in different environmental samples. The commonly used analytical extraction methods for TCS and related compounds include solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, liquid-phase microextraction, and so on. The determination methods include liquid chromatography coupled with different detectors, gas chromatography and related methods, sensors, electrochemical method, capillary electrophoresis. The removal techniques in various environmental samples mainly include biodegradation, advanced oxidation, and adsorption methods. Besides, both the pros and cons of different techniques have been compared and summarized, and the development and prospect of each technique have been given.

Comprehensive insight into triclosan-from widespread occurrence to health outcomes

Humans are exposed to the variety of emerging environmental pollutant in everyday life. The special concern is paid to endocrine disrupting chemicals especially to triclosan which could interfere with normal hormonal functions. Triclosan could be found in numerous commercial products such as mouthwashes, toothpastes and disinfectants due to its antibacterial and antifungal effects. Considering the excessive use and disposal, wastewaters are recognized as the main source of triclosan in the aquatic environment. As a result of the incomplete removal, triclosan residues reach surface water and even groundwater. Triclosan has potential to accumulate in sediment and aquatic organisms. Therefore, the detectable concentrations of triclosan in various environmental and biological matrices emerged concerns about the potential toxicity. Triclosan impairs thyroid homeostasis and could be associated with neurodevelopment impairment, metabolic disorders, cardiotoxicity and the increased cancer risk. The growing resistance of the vast groups of bacteria, the evidenced toxicity on different aquatic organisms, its adverse health effects observed in vitro, in vivo as well as the available epidemiological studies suggest that further efforts to monitor triclosan toxicity at environmental levels are necessary. The safety precaution measures and full commitment to proper legislation in compliance with the environmental protection are needed in order to obtain triclosan good ecological status. This paper is an overview of the possible negative triclosan effects on human health. Sources of exposure to triclosan, methods and levels of detection in aquatic environment are also discussed.

Neurotoxic mechanisms of triclosan: The antimicrobial agent emerging as a toxicant

Several scientific studies have suggested a link between increased exposure to pollutants and a rise in the number of neurodegenerative disorders of unknown origin. Notably, triclosan (an antimicrobial agent) is used in concentrations ranging from 0.3% to 1% in various consumer products. Recent studies have also highlighted triclosan as an emerging toxic pollutant due to its increasing global use. However, a definitive link is missing to associate the rising use of triclosan and the growing number of neurodegenerative disorders or neurotoxicity. In this article, we present systematic scientific evidence which are otherwise scattered to suggest that triclosan can indeed induce neurotoxic effects, especially in vertebrate organisms including humans. Mechanistically, triclosan affected important developmental and differentiation genes, structural genes, genes for signaling receptors and genes for neurotransmitter controlling enzymes. Triclosan-induced oxidative stress impacting cellular proteins and homeostasis which triggers apoptosis. Though the scientific evidence collated in this article unequivocally indicates that triclosan can cause neurotoxicity, further epidemiological studies may be needed to confirm the effects on humans.

Early life exposure to triclosan from antimicrobial daily necessities may increase the potential risk of autism spectrum disorder: A multicenter study in China

BACKGROUND

Autism spectrum disorders (ASD) are a group of complex neurodevelopmental disorders with unclear etiologies. Our recent work indicated that maternal exposure to triclosan (TCS) significantly increased the autistic-like behavior in rats, possibly through disrupting neuronal retinoic acid signaling. Although environmental endocrine disruptors (EEDs) have been associated with autism in humans, the relationship between TCS, one of the EEDs found in antibacterial daily necessities, and autism has received little attention.

OBJECTIVE

The aims of this multicenter study were to evaluate TCS concentrations in typically developing (TD) children and ASD children, and to determine the relationship between TCS levels and the core symptoms of ASD children.

METHODS

A total of 1345 children with ASD and 1183 TD children were enrolled from 13 cities in China. Ages ranged between 2 and 7 years. A questionnaire was used to investigate the maternal use of antibacterial daily necessities (UADN) during pregnancy. The core symptoms of ASD were evaluated using the Autism Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), Social Response Scale (SRS), and the Children Neuropsychological and Behavior Scale-Revision 2016 (CNBS-R2016). The TCS concentration was measured using LC-MS/MS.

RESULTS

Maternal UADN during pregnancy may be an unrecognized potential environmental risk factor for ASD (OR=1.267, P = 0.023). Maternal UADN during pregnancy strongly correlated with TCS levels in the offspring (Adjusted β = 0.277, P < 0.001). TCS concentration was higher in ASD children (P = 0.005), and positively correlated with ABC (Sensory subscales: P = 0.03; Social self-help subscales: P = 0.011) and SRS scale scores (Social awareness subscales: P = 0.045; Social communication subscales: P = 0.001; Autism behavior mannerisms subscales: P = 0.006; SRS total score: P = 0.003) in ASD children. This association was more pronounced in boys than in girls.

CONCLUSION

To our knowledge, this is the first case-control study to examine the correlation between TCS and ASD. Our results suggest that maternal UADN during pregnancy may be a potential risk of ASD in offspring. Further detection of TCS levels showed that maternal UADN during pregnancy may be associated with excessive TCS exposure. In addition, the level of TCS in children with ASD is higher than TD children. The higher levels of TCS in children with ASD may be significantly associated with more pronounced core symptoms, and this association was more significant in male children with ASD.

Study on the toxic-mechanism of triclosan chronic exposure to zebrafish (Danio rerio) based on gut-brain axis

Triclosan (TCS), as a broad-spectrum bactericide, is extensively used in the fine chemical and textile industries. It is recognized as a new type of environmental endocrine disruptor with frequent detection and environmental pollution. However, the toxicity mechanism regarding neurodevelopment and neurobehavior remains unclear. This study is intended to explore the underlying toxic mechanism of TCS based on gut-brain axis. TCS-chronic exposure affected the development of zebrafish, induced feminization, obesity physical signs and abnormal organ index and caused neurobehavioral abnormalities by inhibiting both neurotransmitter acetylcholinesterase and dopamine activity, promoting brain neuron apoptosis and accelerating diencephalic lesions. Meanwhile, TCS-chronic exposure led to gut microbiota dysbiosis and decreased diversity, such as increased pathogenic bacteria and decreased probiotics in adult zebrafish gut, which caused many pathological damages, including partial shedding and ablation of intestinal villi, inflammatory infiltration, thinning of intestinal wall, and increased goblet cell in villus. Based on the communication between intestinal peripheral nerves and CNS, the above histopathological injuries and disorders were well underpinned and illustrated by the changes of biomarkers and the expression of related marker genes in the gut-brain axis. Additionally, short-chain fatty acids (SCFA), as the regulators of intestinal sympathetic nerve activation, are also secreting products of intestinal microflora and play a crucial role in regulating the balance of intestinal flora and protecting intestinal homeostasis. SCFA in low doses can effectively alleviate and rescue the toxic effects under TCS exposure, which evidenced that TCS exerted systemic toxic effects on the gut-brain axis by influencing the composition and diversity of gut flora in zebrafish, and fully demonstrated the interaction effect between intestine and brain. Hence, these findings contribute to the understanding, prevention, and diagnosis of endocrine disrupting diseases caused by environmental pollutants from the perspective of the gut-brain axis, and strengthening the early warning, management and control of TCS pollution.

The Transcranial Light Therapy Improves Synaptic Plasticity in the Alzheimer’s Disease Mouse Model

Alzheimer’s disease (AD) is the main cause of dementia worldwide. Emerging non-invasive treatments such as photobiomodulation target the mitochondria to minimize brain damage, improving cognitive functions. In this work, an experimental design was carried out to evaluate the effect of transcranial light therapy (TLTC) on synaptic plasticity (SP) and cognitive functions in an AD animal model. Twenty-three mice were separated into two general groups: an APP/PS1 (ALZ) transgenic group and a wild-type (WT) group. Each group was randomly subdivided into two subgroups: mice with and without TLTC, depending on whether they would undergo treatment with TLTC. Cognitive function, measured through an object recognition task, showed non-significant improvement after TLTC. SP, on the other hand, was evaluated using four electrophysiological parameters from the Schaffer-CA1 collateral hippocampal synapses: excitatory field potentials (fEPSP), paired pulse facilitation (PPF), long-term depression (LTD), and long-term potentiation (LTP). An improvement was observed in subjects treated with TLTC, showing higher levels of LTP than those transgenic mice that were not exposed to the treatment. Therefore, the results obtained in this work showed that TLTC could be an efficient non-invasive treatment for AD-associated SP deficits.

Bibliometric Analysis: The Effects of Triclosan on Human Health

Triclosan (TCS) is a widely used chemical whose effects on human health remains elusive. TCS may play a role in a variety of health issues, including endocrine dysfunction, irregular embryonic development, and immune suppression. It is possible that TCS's penetrative abilities across all body barriers, including the blood-brain barrier, may make bioaccumulation the primary driver of these issues. In addition, chronic overuse of this chemical in everyday life may further contribute to the already increasing problem of antibiotic resistance. TCS research has steadily increased since its transition from medical to commercial use over the last 50 years. However, there are some clear gaps in the depth of this research as the safety of this agent is not fully agreed upon. The Food and Drug Administration recently issued regulatory rules regarding TCS in some commercial products; however, it is still found in a variety of goods marketed as "antimicrobial" or "antibacterial". The purpose of this bibliometric study is to analyze research trends in this field and determine the amount of global attention TCS has received as to its relevancy in human health. Documenting and determining research concentration trends related to this field may outline where additional research is most necessary, as well as demonstrate the most valuable research produced and its relation to the advancement of our understanding of TCS. We found there to be a shift in research from TCS and its role in medical environments, to research based on the indirect effects of TCS through environmental contaminations, such as the propagation of antibiotic resistance. This shift was coupled with an increase in global research related to this field and identified China as a significant contributor. Although TCS has received notice, the simple fact of its continued use in so many common products, as well as the unclear understanding of its direct health impacts, reinforces the need for additional and more conclusive research before it has possible irreversible effects on our environment and health.

Maternal exposure to triclosan during lactation alters social behaviors and the hippocampal ultrastructure in adult mouse offspring

We recently reported that exposure to triclosan (TCS), a broad-spectrum antibacterial agent, affects social behaviors in adult mice, however, the long-lasting effects of TCS exposure during early life on social behaviors are still elusive. The present study aimed to investigate the long-lasting impacts of adding TCS to the maternal drinking water during lactation on the social behaviors of adult mouse offspring and to explore the potential mechanism underlying these effects. The behavioral results showed that TCS exposure decreased body weight, increased depression-like behavior and decreased social dominance in both male and female offspring, as well as increased anxiety-like behavior and bedding preference in female offspring. In addition, enzyme-linked immunosorbent assay (ELISA) indicated that TCS exposure increased peripheral proinflammatory cytokine levels, altered serum oxytocin (OT) levels, and downregulated the expression of postsynaptic density protein 95 (PSD-95) in the hippocampus. Morphological analysis by transmission electron microscopy (TEM) demonstrated that exposure to TCS induced morphological changes to synapses and neurons in the hippocampus of offspring. These findings suggested that TCS exposure during lactation contributed to abnormal social behaviors accompanied by increased peripheral inflammation and altered hippocampal neuroplasticity, which provides a deeper understanding of the effects of TCS exposure during early life on brain function and behavioral phenotypes.

Effects of chronic triclosan exposure on social behaviors in adult mice

Triclosan (TCS), a newly identified environmental endocrine disruptor (EED) in household products, has been reported to have toxic effects on animals and humans. The effects of TCS exposure on individual social behaviors and the potential underlying mechanisms are still unknown. This study investigated the behavioral effects of 42-day exposure to TCS (0, 50, 100 mg/kg) in drinking water using the open field test (OFT), social dominance test (SDT), social interaction test (SIT), and novel object recognition task (NOR). Using 16S rRNA sequencing analysis and transmission electron microscopy (TEM), we observed the effects of TCS exposure on the gut microbiota and ultrastructure of hippocampal neurons and synapses. Behavioral results showed that chronic TCS exposure reduced the social dominance of male and female mice. TCS exposure also reduced social interaction in male mice and impaired memory formation in female mice. Analysis of the gut microbiota showed that TCS exposure increased the relative abundance of the Proteobacteria and Actinobacteria phyla in female mice. Ultrastructural analysis revealed that TCS exposure induced ultrastructural damage to hippocampal neurons and synapses. These findings suggest that TCS exposure may affect social behaviors, which may be caused by altered gut microbiota and impaired plasticity of hippocampal neurons and synapses.

Triclosan-induced glycolysis drives inflammatory activation in microglia via the Akt/mTOR/HIF 1α signaling pathway

Exposure to triclosan (TCS) has been implicated in neurotoxicity including autism spectrum disorders in vivo and oxidative stress and cell apoptosis in vitro. Thus, the molecular mechanisms underlying TCS-induced neurotoxicity warrants further research. In this study, we try to address the mode of action that TCS induced the expression of inflammatory cytokines by shifting metabolism to glycolysis. BV-2 cells were treated with 20 μM TCS for 24 h, and the conditional medium from TCS-induced activated microglia reduced the viability of the murine hippocampal neurons cell line HT22. Protein expression levels in the nuclear factor kappa B (NF-κB) signaling pathway were measured through Western blotting, and the expression levels of inflammatory cytokine were measured using quantitative real-time PCR. The results showed that exposure to TCS enhanced NF-κB activation, increased inflammatory cytokine expression including interleukin (IL) 1β, IL-6, and tumor necrosis factor (TNF) α in the BV-2 cells. The glucose consumption and lactate production in BV2 cell increased sharply after exposure to TCS for 24 h. Based on our qPCR and Western blotting results, the expression of the key glycolysis enzymes-namely hexokinase 1, pyruvate kinase M2, and lactate dehydrogenase A-increased after treatment with 20 μM TCS. Furthermore, inhibiting glycolysis by 2-deoxy-D-glucose reduced the activation of NF-κB and the mRNA expression of the inflammatory cytokines in the TCS-activated BV-2 microglia. The expression of the proteins of the Akt/mTOR/HIF1α pathway examined through Western blotting, which regulates glycolysis, also increased in the BV2 cells exposed to TCS. Moreover, Akt and mTOR inhibition by using LY294002 and rapamycin, respectively, blocked inflammatory cytokine overexpression induced by TCS. In conclusion, TCS can induce glycolysis and directly drive inflammatory activation in microglia; with the mediation of the Akt/mTOR/HIF1α pathway.

Triclosan disrupts immune cell function by depressing Ca2+ influx following acidification of the cytoplasm

Triclosan (TCS) is an antimicrobial agent that was effectively banned by the FDA from hand soaps in 2016, hospital soaps in 2017, and hand sanitizers in 2019; however, TCS can still be found in a few products. At consumer-relevant, non-cytotoxic doses, TCS inhibits the functions of both mitochondria and mast cells, a ubiquitous cell type. Via the store-operated Ca2+ entry mechanism utilized by many immune cells, mast cells undergo antigen-stimulated Ca2+ influx into the cytosol, for proper function. Previous work showed that TCS inhibits Ca2+ dynamics in mast cells, and here we show that TCS also inhibits Ca2+ mobilization in human Jurkat T cells. However, the biochemical mechanism behind the Ca2+ dampening has yet to be elucidated. Three-dimensional super-resolution microscopy reveals that TCS induces mitochondrial swelling, in line with and extending the previous finding of TCS inhibition of mitochondrial membrane potential via its proton ionophoric activity. Inhibition of plasma membrane potential (PMP) by the canonical depolarizer gramicidin can inhibit mast cell function. However, use of the genetically encoded voltage indicators (GEVIs) ArcLight (pH-sensitive) and ASAP2 (pH-insensitive), indicates that TCS does not disrupt PMP. In conjunction with data from a plasma membrane-localized, pH-sensitive reporter, these results indicate that TCS, instead, induces cytosolic acidification in mast cells and T cells. Acidification of the cytosol likely inhibits Ca2+ influx by uncoupling the STIM1/ORAI1 interaction that is required for opening of plasma membrane Ca2+ channels. These results provide a mechanistic explanation of TCS disruption of Ca2+ influx and, thus, of immune cell function.

Biomarkers for the toxicity of sublethal concentrations of triclosan to the early life stages of carps

Accumulation, contents of protein, non-enzymatic antioxidant glutathione (GSH and GSSG), lipid peroxidation product (melondialdehyde-MDA) and organic acids (fumarate, succinate, malate and citrate), and activities of neurological (acetylcholinesterase-AChE), detoxification (glutathione S-transferase-GST) and metabolic (lactate dehydrogenase-LDH, aspartate transaminase-AST and alanine transaminase-ALT) enzymes were recorded in the hatchlings of Cyprinus carpio, Ctenopharyngodon idella, Labeo rohita and Cirrhinus mrigala after 7 and 14 days exposure and 10 days post exposure (recovery period) to sublethal concentrations (0.005, 0.01, 0.02 and 0.05 mg/L) of triclosan, a highly toxic and persistent biocide used in personal care products. Accumulation was maximum between 7-14 days at 0.01 mg/L for C. carpio and L. rohita but at 0.005 mg/L for C. idella and C. mrigala. No triclosan was observed at 0.005 mg/L in C. carpio and C. mrigala after recovery. Significant decline in protein, glutathione and acetylcholinesterase but increase in glutathione S-transferase, lactate dehydrogenase, aspartate transaminase, alanine transaminase, melondialdehyde and organic acids over control during exposure continued till the end of recovery period. Integrated biomarker response (IBR) analysis depicted higher star plot area for glutathione and glutathione S-transferase during initial 7 days of exposure, thereafter, during 7-14 days of exposure and the recovery period, higher star plot area was observed for acetylcholinesterase, aspartate transaminase, alanine transaminase and organic acids. Higher star plot area was observed for protein in all the species throughout the study. The study shows that L. rohita is most sensitive and glutathione, acetylcholinesterase, aspartate transaminase and alanine transaminase are the biomarkers for the toxicity of sublethal concentrations of TCS.

Perinatal Exposure to Triclosan Results in Abnormal Brain Development and Behavior in Mice

Triclosan (TCS) is one of the most common endocrine-disrupting chemicals (EDCs) present in household and personal wash products. Recently, concerns have been raised about the association between abnormal behavior in children and exposure to EDC during gestation. We hypothesized that exposure to TCS during gestation could affect brain development. Cortical neurons of mice were exposed in vitro to TCS. In addition, we examined in vivo whether maternal TCS administration can affect neurobehavioral development in the offspring generation. We determined that TCS can impair dendrite and axon growth by reducing average length and numbers of axons and dendrites. Additionally, TCS inhibited the proliferation of and promoted apoptosis in neuronal progenitor cells. Detailed behavioral analyses showed impaired acquisition of spatial learning and reference memory in offspring derived from dams exposed to TCS. The TCS-treated groups also showed cognition dysfunction and impairments in sociability and social novelty preference. Furthermore, TCS-treated groups exhibited increased anxiety-like behavior, but there was no significant change in depression-like behaviors. In addition, TCS-treated groups exhibited deficits in nesting behavior. Taken together, our results indicate that perinatal exposure to TCS induces neurodevelopment disorder, resulting in abnormal social behaviors, cognitive impairment, and deficits in spatial learning and memory in offspring.

Triclosan induces PC12 cells injury is accompanied by inhibition of AKT/mTOR and activation of p38 pathway

Triclosan (TCS) has been widely used as a disinfectant and antiseptic in multiple consumer and healthcare products due to its clinical effectiveness against various bacteria, fungi and protozoa. Recently, several studies have reported the adverse effects of TCS on various nerve cells, arousing concerns about its potential neurotoxicity. The present study aimed to investigate the neurotoxicity of TCS in rat pheochromocytoma PC12 cells. After differentiation, the stabilized PC12 cells were treated with 1, 10, 50 μM TCS for 12 h. At the end of the treatment, the generation of reactive oxygen species (ROS), protein expression of apoptotic-related genes, AMPK-AKT/mTOR, as well as p38 in PC12 cells were determined. The concentrations were chosen based on the results of cell viability and lactic dehydrogenase (LDH) assays in response to TCS treatment (ranging from 0.001 to 100 μM) for varied time periods. The results showed that TCS is cytotoxic to PC12 cells, causing decreased cell viability accompanied by increased LDH release. TCS treatment at 10 and 50 μM for 12 h increased the mRNA and protein expression of the pro-apoptotic gene Bax, while Bcl-2 levels remained unchanged. Moreover, an increase in the generation of reactive oxygen species (ROS) was found in TCS-treated PC12 cells at the concentrations of 1 and 10 μM. Pretreatment with 100 μM N-acetyl cysteine (NAC- ROS scavenger) for 1 h normalized the ROS generations in TCS-treated PC12 cells. Additionally, the suppression of the phosphorylation of Akt and mTOR was observed in TCS-treated PC12 cells at 10 and 50 μM for 12 h, concomitant with the activation of p38 MAPK pathway at 50 μM TCS. However, there were no effects of TCS on the phosphorylation of AMPK in these cells. Taken together, these results suggest that TCS may cause adverse effects and oxidative stress in PC12 cells accompanied by inhibition of Akt/mTOR and activation of p38.

Research Progress on Toxic Effects and Water Quality Criteria of Triclosan

Triclosan (TCS) is an effective broad-spectrum antimicrobial agent that is widely used in personal care products. It has been detected in different environmental media, and poses high potential ecological risk. In this article, we carried out a literature review of recent studies on the toxic effects of TCS from different aspects at the molecular, cell, tissue, organ, and individual level. TCS can exhibit acute toxicity to aquatic organisms, affect the normal expression and physiological function of enzymes and genes, and produce cytotoxicity. Many studies have demonstrated that TCS exerts significant endocrine-disrupting effects on organisms, interfering the normal physiological functions of the reproductive, thyroid, and nervous systems via related signaling pathways. Moreover, we reported current research on the water quality criteria of TCS and discuss possible future research directions.