The widespread environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a potent toxicant that causes significant neurotoxicity. However, the biological events that participate in this process remain largely elusive. In the present study, we demonstrated that TCDD exposure triggered apparent premature senescence in rat pheochromocytoma (PC12) and human neuroblastoma SH-SY5Y cells. Senescence-associated β-galactosidase (SA-β-Gal) assay revealed that TCDD induced senescence in PC12 neuronal cells at doses as low as 10 nM. TCDD led to F-actin reorganization and the appearance of an alternative senescence marker, γ-H2AX foci, both of which are important features of cellular senescence. In addition, TCDD exposure altered the expression of senescence marker proteins, such as p16, p21 and p-Rb, in both dose- and time-dependent manners. Furthermore, we demonstrated that TCDD promotes mitochondrial dysfunction and the accumulation of cellular reactive oxygen species (ROS) in PC12 cells, leading to the activation of signaling pathways that are involved in ROS metabolism and senescence. TCDD-induced ROS generation promoted significant oxidative DNA damage and lipid peroxidation. Notably, treatment with the ROS scavenger N-acetylcysteine (NAC) markedly attenuated TCDD-induced ROS production, cellular oxidative damage and neuronal senescence. Moreover, we found that TCDD induced a similar ROS-mediated senescence response in human neuroblastoma SH-SY5Y cells. In sum, these results demonstrate for the first time that TCDD induces premature senescence in neuronal cells by promoting intracellular ROS production, supporting the idea that accelerating the onset of neuronal senescence may be an important mechanism underlying TCDD-induced neurotoxic effects.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is widely considered as the most toxic and common carcinogen in the world. Exposure to TCDD causes liver lipid metabolism disorder and steatosis. However, the molecular mechanism of TCDD-induced liver lipid accumulation is not completely clear. Here, we found that a 5 μg/kg TCDD exposure for 3 weeks induced hepatocyte lipid deposition, increased CD36 expression, and promoted AMP-activated protein kinase (AMPK) ɑ phosphorylation in the liver of C57BL/6J mice. Furthermore, sulfo-N-succinimidyl oleate, a CD36 inhibiter, blunted TCDD-induced lipid deposition in Huh7 cells, confirming the critical role of CD36 in TCDD-induced hepatic steatosis. In terms of molecular mechanisms, we found that TCDD exposure increased reactive oxygen species (ROS) levels in Huh7 cells, which activated AMPK. Moreover, the activated AMPK upregulated CD36 expression. Therefore, we can see that the increase in CD36 expression induced by TCDD was regulated by ROS/AMPK/CD36 signaling pathway. Our results help to clarify the molecular mechanism of TCDD-induced hepatic steatosis.

Both chronic calorie restriction (CCR) and intermittent calorie restriction (ICR) have shown anticancer effects. However, the direct evidence comparing ICR to CCR with respect to cancer prevention is controversial and inconclusive. PubMed and Web of Science were searched on November 25, 2015. The relative risk (RR) [95% confidence interval (CI)] was calculated for tumor incidence and the standardised mean difference (95% CI) was computed for levels of serum insulin-like growth factor-1 (IGF-1), leptin and adiponectin using a random-effects meta-analysis. Sixteen studies were identified, including 11 using genetically engineered mouse models (908 animals with 38–76 weeks of follow-up) and 5 using chemically induced rat models (379 animals with 7–18 weeks of follow-up). Compared to CCR, ICR decreased tumor incidence in genetically engineered models (RR = 0.57; 95% CI: 0.37, 0.88) but increased the risk in chemically induced models (RR = 1.53, 95% CI: 1.13, 2.06). It appears that ICR decreases IGF-1 and leptin and increases adiponectin in genetically engineered models. Thus, the evidence suggests that ICR exerts greater anticancer effect in genetically engineered mouse models but weaker cancer prevention benefit in chemically induced rat models as compared to CCR. Further studies are warranted to confirm our findings and elucidate the mechanisms responsible for these effects.

Accumulative evidence in the literature suggests alcohol consumption is a protective factor of the metabolic syndrome (MS). However, few studies investigated the relationship between alcohol consumption and components of MS. We examined association of several types of alcoholic beverage with components of MS among people in rural China. In the Nantong Metabolic Syndrome Study (NMSS), a cross-sectional study, a total of 20,502 participants, including 13,505 women and 6,997 men aged 18–74 years, were recruited between 2007 and 2008 in Nantong, China. Socio-economic status, dietary intake, physical exercise, alcoholic beverage consumption, and smoking status information were obtained, and triglycerides (TG), high-density lipoprtein cholesterol (HDL-c), blood pressure (BP) and blood glucose level were examined for all participants. Logistic regression model and the restricted cubic spline approach were used to analyze the associations between alcoholic beverage consumption and MS components. The MS prevalence was 21.1% in the whole population, which was significantly low among drinkers (20.6%), compared with non-drinkers (23.6%) in women, and was comparable in men (16.4% versus 17.1%). High HDL-c level was observed among drinkers, compared with non-drinkers in both men and women. Low TG level and Systolic BP (SBP) were found only among rice wine drinkers in women, and high waist circumference, high TG and BP were found among beer and liquor drinkers in men. Furthermore, we found that the highest quartile of rice wine drink in women may decrease 24% risk of high TG, 30% risk of low HDL-c and 43% risk of high glucose among MS components cases respectively, compared with non-drinkers (p for trend <0.01 for those three components). While compared non-drinkers among men, the highest quartile of liquor drink may increase 32% risk of high SBP, 55% risk of high Diastolic BP (DBP) and 34% risk of abdominal obesity among MS components cases respectively, but decrease 45% risk of low HDL-c (p for trend <0.05 for those four components). Our data suggested that all alcoholic beverages increased HDL-c level. Rice wine decreased both TG level and blood glucose in women only and it could be one of healthy alcoholic beverages in MS prevention in Chinese women. While excessive liquor consumption increased BP and waist circumference level and it may lead to hypertension and central obesity in Chinese men.