Betaine, heavy metal protection, oxidative stress, and the liver

Environmentally Relevant Concentrations of S-6PPD-Quinone Caused More Serious Hepatotoxicity Than R-Enantiomer and Racemate in Oncorhynchus mykiss

6PPD-quinone (6PPD-Q) is frequently detected in various environmental media, and the environmentally relevant concentrations can be fatal to Oncorhynchus mykiss. Notably, 6PPD-Q has two enantiomers (S-6PPD-Q and R-6PPD-Q). In this study, O. mykiss was separately exposed to each enantiomer and racemate of 6PPD-Q for 96 h at environmentally relevant concentrations, and livers were collected. Effects on the biochemical, pathological, and ultrastructural changes were assessed, and metabolomics was conducted to elucidate the potential hepatotoxicity mechanism. Compared with the control treatment, the levels of catalase (CAT, all treatments except for 0.1 μg/L rac-6PPD-Q), and glutathione-S-transferase (GST, all treatments) significantly declined. Hepatocyte space became smaller, nuclear morphology changed, and nucleolysis occurred. Mitochondrial malformation and vesicle-like structure dilation of the endoplasmic reticulum (ER) were observed in the hepatocytes, which was most serious after S-6PPD-Q exposure. Some amino acid metabolism, folate biosynthesis, taurine and hypotaurine metabolism and purine metabolism were disturbed, consistent with mitochondrial dysfunction and ER stress. The differential metabolites were in the order of S-6PPD-Q (216) > rac-6PPD-Q (88) > R-6PPD-Q (56). Thus, 6PPD-Q-induced hepatic mitochondrial dysfunction and ER stress, causing metabolic disturbance and oxidative stress might be the toxic mechanism of 6PPD-Q in O. mykiss liver, and S-6PPD-Q effects were the most serious.

Betaine ameliorates arsenic-induced kidney injury in mice by mitigating oxidative stress-mediated inflammation

Arsenic, an environmental pollutant and poisonous metalloid, has adverse effects on different body organs, including the kidneys. Betaine is a natural nutrient that has many beneficial health effects. This research was conducted to examine the impact of betaine on nephrotoxicity caused by inorganic arsenic (NaAsO2) in mice. Mice were separated into following groups: control, NaAsO2 (50 ppm), NaAsO2 (50 ppm) + betaine (500 mg/kg), and betaine (500 mg/kg). Mice were received NaAsO2 via drinking water for 8 consecutive weeks and betaine was given to the animals via gavage once daily in the 7th and 8th weeks of the study. Upon completion of the study, the mice were euthanized and samples of serum and kidney were obtained for further evaluations. Administration of NaAsO2 increased the levels of blood urea nitrogen and creatinine in the serum. It enhanced the amounts of renal malondialdehyde and decreased the total thiol levels, as well as the activity of antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase). Furthermore, it enhanced the levels of renal inflammatory indicators (tumor necrosis factor-alpha and nitric oxide). Western blot results exhibited an increase in the protein expression of nuclear factor kappa B (NF-κB), and phosphorylated NF-κB in NaAsO2-treated mice. Histopathological results also confirmed kidney damage caused by NaAsO2. However, treatment with betaine improved NaAsO2-related kidney injuries in mice. The results of this work indicated that betaine can attenuate kidney damage caused by NaAsO2 by inhibiting oxidative stress and inflammation.

Alleviative Effect of Threonine on Cadmium-Induced Liver Injury in Mice

As a toxic trace element commonly found in food, cadmium (Cd) can cause severe liver injury. Our previous study showed that threonine (Thr) could significantly alleviate Cd toxicity in yeast. To investigate the effect of Thr on Cd-induced liver injury in mice, twenty-four mice were randomly divided into four groups: control, Cd, and low/high dose of Thr-treatment groups (0.04 and 0.08 mmol/kg/day, respectively). After 7 days of continuous treatment, the alleviative effect of Thr on liver injury in Cd-exposed mice was assessed. The results showed that Thr significantly reduced the elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in Cd-exposed mice. Histological analysis showed that Thr decreased Cd-induced hepatic steatosis, zonal necrosis, and inflammatory cell infiltration. Thr also reduced the Cd-induced malondialdehyde (MDA) and O^2- levels and restored superoxide dismutase (SOD) and catalase (CAT) activities in the liver. Further investigation showed that Thr significantly suppressed Cd-induced inflammatory response (tumor necrosis factor-α and interleukin-6) and restored the level of anti-apoptotic protein (Blc-2) but inhibited the elevation of pro-apoptotic proteins (Bax and caspase-3), as well as the activation of the PI3K/AKT signaling pathway in Cd-exposed mice. In conclusion, Thr alleviated Cd-induced liver injury through reducing Cd-induced oxidative stress, inflammation, and attenuating hepatocyte apoptosis via PI3K/AKT-related signaling pathway.

Drug-induced organ injury in coronavirus disease 2019 pharmacotherapy: Mechanisms and challenges in differential diagnosis and potential protective strategies

The world is currently facing an unprecedented pandemic caused by a newly recognized and highly pathogenic coronavirus disease 2019 (COVID-19; induced by SARS-CoV-2 virus), which is a severe and ongoing threat to global public health. Since COVID-19 was officially declared a pandemic by the World Health Organization in March 2020, several drug regimens have rapidly undergone clinical trials for the management of COVID-19. However, one of the major issues is drug-induced organ injury, which is a prominent clinical challenge. Unfortunately, most drugs used against COVID-19 are associated with adverse effects in different organs, such as the kidney, heart, and liver. These side effects are dangerous and, in some cases, they can be lethal. More importantly, organ injury is also a clinical manifestation of COVID-19 infection. These adverse reactions are increasingly recognized as outcomes of COVID-19 infection. Therefore, the differential diagnosis of drug-induced adverse effects from COVID-19-induced organ injury is a clinical complication. This review highlights the importance of drug-induced organ injury, its known mechanisms, and the potential therapeutic strategies in COVID-19 pharmacotherapy. We review the potential strategies for the differential diagnosis of drug-induced organ injury. This information can facilitate the development of therapeutic strategies, not only against COVID-19 but also for future outbreaks of other emerging infectious diseases.

The Role of Mitochondrial Impairment and Oxidative Stress in the Pathogenesis of Lithium-Induced Reproductive Toxicity in Male Mice

Lithium (Li+) is prescribed against a wide range of neurological disorders. Besides its excellent therapeutic properties, there are several adverse effects associated with Li+. The impact of Li+ on renal function and diabetes insipidus is the most common adverse effect of this drug. On the other hand, infertility and decreased libido is another complication associated with Li+. It has been found that sperm indices of functionality, as well as libido, is significantly reduced in Li+-treated men. These adverse effects might lead to drug incompliance and the cessation of drug therapy. Hence, the main aims of the current study were to illustrate the mechanisms of adverse effects of Li+ on the testis tissue, spermatogenesis process, and hormonal changes in two experimental models. In the in vitro experiments, Leydig cells (LCs) were isolated from healthy mice, cultured, and exposed to increasing concentrations of Li+ (0, 10, 50, and 100 ppm). In the in vivo section of the current study, mice were treated with Li+ (0, 10, 50, and 100 ppm, in drinking water) for five consecutive weeks. Testis and sperm samples were collected and assessed. A significant sign of cytotoxicity (LDH release and MTT assay), along with disrupted testosterone biosynthesis, impaired mitochondrial indices (ATP level and mitochondrial depolarization), and increased biomarkers of oxidative stress were detected in LCs exposed to Li+. On the other hand, a significant increase in serum and testis Li+ levels were detected in drug-treated mice. Moreover, ROS formation, LPO, protein carbonylation, and increased oxidized glutathione (GSSG) were detected in both testis tissue and sperm specimens of Li+-treated mice. Several sperm anomalies were also detected in Li+-treated animals. On the other hand, sperm mitochondrial indices (mitochondrial dehydrogenases activity and ATP levels) were significantly decreased in drug-treated groups where mitochondrial depolarization was increased dose-dependently. Altogether, these data mention oxidative stress and mitochondrial impairment as pivotal mechanisms involved in Li+-induced reproductive toxicity. Therefore, based on our previous publications in this area, therapeutic options, including compounds with high antioxidant properties that target these points might find a clinical value in ameliorating Li+-induced adverse effects on the male reproductive system.