Souza-Talarico Juliana N, Suchecki Deborah, Juster Robert-Paul, Plusquellec Pierrich, Barbosa Junior Fernando, Bunscheit Vinícius, Marcourakis Tania, de Matos Tatiane Martins, Lupien Sonia J
Department of Medical-Surgical Nursing, School of Nursing, Universidade de São Paulo, São Paulo 05403 000, Brazil.
Department of Psychobiology, Universidade Federal de São Paulo, São Paulo 04023-062, Brazil.
Environ Res. 2017 Apr;154:261-268. doi: 10.1016/j.envres.2017.01.012. Epub 2017 Jan 19.
Lead levels (Pb) have been linked to both hyper- and hypo-reactivity of hypothalamic-pituitary-adrenal axis (HPA) axis to acute stress in animals and humans. Similarly, allostatic load (AL), the 'wear and tear' of chronic stress, is associated with inadequate HPA axis activity. We examined whether Pb levels would be associated with altered diurnal cortisol profile, as a primary mediator of AL, during aging. Pb levels were measured from blood samples (BPb) of 126 Brazilian individuals (105 women), between 50 and 82 years old. Six neuroendocrine, metabolic, and anthropometric biomarkers were analyzed and values were transformed into an AL index using clinical reference cut-offs. Salivary samples were collected at home over 2 days at awakening, 30-min after waking, afternoon, and evening periods to determine cortisol levels. A multiple linear regression model showed a positive association between BPb as the independent continuous variable and cortisol awakening response (R=0.128; B=0.791; p=0.005) and overall cortisol concentration (R=0.266; B=0.889; p<0.001) as the outcomes. Repeated measures ANOVA showed that individuals with high BPb levels showed higher cortisol at 30min after awakening (p=0.003), and in the afternoon (p=0.002) than those with low BPb values. Regarding AL, regression model showed that BPb was positively associated with AL index (R=0.100; B=0.204; p=0.032). Correlation analyzes with individual biomarkers showed that BPb was positively correlated with HDL cholesterol (p=0.02) and negatively correlated with DHEA-S (p=0.049). These findings suggest that Pb exposure, even at levels below the reference blood lead level for adults recommended by the National Institute for Occupational Safety and Health and by the Center for Disease Control and Prevention, may contribute to AL and dysregulated cortisol functioning in older adults. Considering these findings were based on cross-sectional data future research is needed to confirm our exploratory results.
铅水平（Pb）与动物和人类下丘脑-垂体-肾上腺轴（HPA轴）对急性应激的高反应性和低反应性均有关联。同样，慢性应激的“损耗”——负荷过重（AL），与HPA轴活动不足有关。我们研究了在衰老过程中，作为AL主要调节因子的铅水平是否会与昼夜皮质醇水平的改变相关。测量了126名年龄在50至82岁之间的巴西人（105名女性）血液样本中的铅水平（BPb）。分析了六种神经内分泌、代谢和人体测量生物标志物，并使用临床参考临界值将其转化为AL指数。在家中于两天内的觉醒时、醒来后30分钟、下午和晚上时段采集唾液样本以测定皮质醇水平。多元线性回归模型显示，作为独立连续变量的BPb与皮质醇觉醒反应（R = 0.128；B = 0.791；p = 0.005）以及总皮质醇浓度（R = 0.266；B = 0.889；p < 0.001）之间呈正相关。重复测量方差分析显示，BPb水平高的个体在醒来后30分钟（p = 0.003）和下午（p = 0.002）的皮质醇水平高于BPb值低的个体。关于AL，回归模型显示BPb与AL指数呈正相关（R = 0.100；B = 0.204；p = 0.032）。与个体生物标志物的相关性分析显示，BPb与高密度脂蛋白胆固醇呈正相关（p = 0.02），与硫酸脱氢表雄酮呈负相关（p = 0.049）。这些发现表明，即使铅暴露水平低于美国国家职业安全与健康研究所和疾病控制与预防中心推荐的成人参考血铅水平，也可能导致老年人的AL和皮质醇功能失调。鉴于这些发现基于横断面数据，需要进一步的研究来证实我们的探索性结果。
