Association between dietary intake of α-tocopherol and cadmium related osteoporosis in population ≥ 50 years.

INTRODUCTION: To analyze the association between α-tocopherol intake and cadmium (Cd) exposure and osteoporosis in population ≥ 50 years. MATERIALS AND METHODS: Sociodemographic data, physical examination, and laboratory indicators including serum Cd level and dietary α-tocopherol intake of 8459 participants were extracted from the National Health and Nutrition Examination Survey (NHANES) database in this cross-sectional study. The associations between α-tocopherol intake, serum Cd levels and osteoporosis were evaluated using univariate and multivariate logistic regression analyses, with the estimated value (ß), odds ratios (ORs) and 95% confidence intervals (CIs). We further explored the impact of α-tocopherol intake on Cd exposure and the bone mineral density (BMD) in total femur and femur neck. RESULTS: A total of 543 old adults suffered from osteoporosis. The serum Cd level (0.52 µg/L vs. 0.37 µg/L) and α-tocopherol intake (5.28 mg vs. 6.50 mg) were statistical different in osteoporosis group and non-osteoporosis group, respectively. High level of Cd exposure was related to the increased risk of osteoporosis [OR = 1.60, 95% CI (1.15-2.21)]. In the total femur, α-tocopherol intake may improve the loss of BMD that associated with Cd exposure [ß = - 0.047, P = 0.037]. Moreover, high α-tocopherol intake combined with low Cd exposure [OR = 0.54, 95% CI (0.36-0.81)] was linked to the decreased risk of osteoporosis comparing with low α-tocopherol intake combined with high Cd exposure. CONCLUSION: High α-tocopherol intake may improve the Cd-related osteoporosis and loss of BMD that could provide some dietary reference for prevention of osteoporosis in population ≥ 50 years old.

Co-exposure of cadmium and lead on bone health in a southwestern Chinese population aged 40-75 years.

Both cadmium (Cd) and lead (Pb) are associated with bone health, but studies exploring the effects of Cd and Pb co-exposure on bone health are rare. This study aimed to assess the interactive effects of Cd and Pb co-exposure on bone health. In total, 799 participants, living in the targeted areas (located in southwestern China) for more than 15 years, aged 40-75 years, and subsisted on homegrown rice and vegetables were investigated. Cd and Pb levels in urine and blood samples, as well as bone mineral density, T- and Z-score were determined. After being adjusted for covariates, the T-score was negatively correlated with blood Pb in men (P < .05); for women and non-smoking women, the T-score was negatively correlated with urinary Pb (P < .05). Moreover, after being adjusted for covariates, the Z-score was negatively correlated with urinary Pb in non-smoking women (P < .05). No positive association of prevalence of osteoporosis with Cd and Pb exposure was found. However, at an additive scale, positive interactions of urinary Cd and Pb on the prevalence of osteoporosis for women and non-smoking women, and the same interactions to blood Cd and Pb for men were found. There was also a positive interaction of urinary Cd and Pb for women at a multiplicative scale. This study suggests Cd and Pb exposure could exert detrimental effects on bone health, with possible underlying interactions. Nevertheless, more studies are needed to explore the interactive effects of heavy metal co-exposure.

Benchmark dose estimation of urinary and blood cadmium as biomarkers of renal dysfunction among 40-75-year-old non-smoking women in rural areas of southwest China.

This study evaluated the association between urinary cadmium (U-Cd) and blood Cd (B-Cd) and several biomarkers of renal dysfunction (α1 -microglobulin [α1 -MG], ß2 -microglobulin [ß2 -MG], N-acetyl-ß-d-glucosaminidase, metallothionein, retinol-binding protein and microalbumin [mALB]) and identified the biomarker(s) that was most closely correlated with U-Cd and B-Cd among female residents in rural areas of southwest China. U-Cd, creatinine (Cr), B-Cd and the above-mentioned six biomarkers in morning spot urine samples were measured from 288 randomly selected 40-75-year-old non-smoking women from non-polluted areas and Cd-polluted-areas. The lower 95% confidence limit of the benchmark dose (BMD) corresponding to the 5% (BMDL05 ) and 10% benchmark response (BMDL10 ) was calculated with assumed cut-off values of the 95th and 90th percentile. Among the investigated women, a significant positive association was found among mALB, ß2 -MG and U-Cd as well as B-Cd. By using the cut-off value of the 95th percentile, the BMDL05 /BMDL10 of U-Cd and B-Cd were 4.33/8.89 µg/g Cr for mALB and 1.35/2.77 µg/L for ß2 -MG, respectively. The BMDL05 /BMDL10 of U-Cd (B-Cd) was 2.73/5.60 µg/g Cr (1.00/2.05 µg/L) for mALB, if the cut-off value was set at the 90th percentile. Therefore, ß2 -MG and mALB in urine were good biomarkers for long-term environmental Cd exposure assessment among the six biomarkers studied for the study pool in southwest China. Our findings may help us to understand the association between nephrotoxicity and Cd exposure, and aid in the decision-making of authorities for environmental Cd pollution and public health.

Dietary cadmium exposure assessment in rural areas of Southwest China.

Dietary exposure of cadmium (Cd) has not been studied in Southwest China. The objective of the study was to determine the pollution characteristics and contamination levels in various agriculture products in Southwest China and to conduct a comparison of dietary exposure assessment of Cd in polluted and non-polluted areas. Results showed that the mean Cd contents in rice were 0.53 and 0.52 mg/kg in the high-polluted and low-polluted areas, respectively, with the average value was 0.03 mg/kg in the control area. The mean dietary Cd exposure from rice and vegetables of the selected non-occupational residents in Southwest China was 113.10 µg/kg bodyweight (bw)/month, 88.80 µg/kg bw/month, and 16.50 µg/kg bw/month in the high-polluted, low-polluted, and control areas, respectively, which correspond to 4.5 times, 3.6 times, and 0.66 times of the provisional tolerable monthly intake (25 µg/kg bw/month) established by the Joint FAO/WHO Expert Committee on Food Additives. The findings indicated that the risk for Cd exposure of residents was high due to home-grown food (most especially rice) being near polluted areas and is of great concern.

Epigallocatechin-3-gallate confers protection against corticosterone-induced neuron injuries via restoring extracellular signal-regulated kinase 1/2 and phosphatidylinositol-3 kinase/protein kinase B signaling pathways.

Extensive studies suggested epigallocatechin-3-gallate (EGCG) has significant neuroprotection against multiple central neural injuries, but the underlying mechanisms still remain poorly elucidated. Here we provide evidence to support the possible involvement of extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphatidylinositol-3 kinase/ protein kinase B (PI3K/AKT) pathways in EGCG-mediated protection against corticosterone-induced neuron injuries. As an essential stress hormone, corticosterone could induce obvious neurotoxicity in primary hippocampal neurons. Pre-treatment with EGCG ameliorated the corticosterone-induced neuronal injuries; however, it was blocked by pharmacological inhibitors for ERK1/2 (U0126) and PI3K/AKT (LY294002). Furthermore, the results confirmed that EGCG restored the corticosterone-induced decrease of ERK1/2 and PI3K/AKT phosphorylation, and attenuated the corticosterone-induced reduction of peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α) expression and ATP production. Taken together, these findings indicated that EGCG has significant neuroprotection against corticosterone-induced neuron injuries partly via restoring the ERK1/2 and PI3K/AKT signaling pathways as well as the PGC-1α-mediated ATP production.

Involvement of PKCα and ERK1/2 signaling pathways in EGCG's protection against stress-induced neural injuries in Wistar rats.

Stress-induced neural injuries are closely linked to the pathogenesis of various neuropsychiatric disorders and psychosomatic diseases. We and others have previously demonstrated certain protective effects of epigallocatechin-3-gallate (EGCG) in stress-induced cerebral impairments, but the underlying protective mechanisms still remain poorly elucidated. Here we provide evidence to support the possible involvement of PKCα and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways in EGCG-mediated protection against restraint stress-induced neural injuries in rats. In both open-field and step-through behavioral tests, the restraint stress-induced neuronal impairments were significantly ameliorated by administration of EGCG or green tea polyphenols (GTPs), which was associated with a partial restoration of normal plasma glucocorticoid, dopamine and serotonin levels. Furthermore, the stress-induced decrease of PKCα and ERK1/2 expression and phosphorylation was significantly attenuated by EGCG and to a less extent by GTP administration. Additionally, EGCG supplementation restored the production of adenosine triphosphate (ATP) and the expression of a key regulator of cellular energy metabolism, the peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α), in stressed animals. In conclusion, PKCα and ERK1/2 signaling pathways as well as PGC-1α-mediated ATP production might be involved in EGCG-mediated protection against stress-induced neural injuries.