Abstract: Objective To investigate the effect of lanthanum exposure on nuclear transcription factor-κB(NF-κB) expression in the hippocampi of offspring rats.Methods Female Wistar rats were obtained from the Center for Experimental Animals of China Medical University.The pregnant rats were exposed to lanthanum chloride(LaCl₃)(99.9%) in distilled drinking water at one of the four doses:0%,0.25%,0.5%,and 1.0%.The offspring rats were exposed to LaCl₃ in utero and while nursing,and then they received 0,0.25,0.50 and 1.00% LaCl₃ orally in distilled drinking water for 1 month.Immunohistochemical assay was used to detect phosphorylated p-IKKα/β expression and distribution.The hippocampi of offspring rats from the four groups were removed to evaluate p-IκBα and p-NF-κBP65 expression.Results Compared with those in the controls,the levels of p-IKKα/β expression in 0.25%,0.5% and 1.0% LaCl₃ groups were 54.72±10.04,40.73±4.90,and 32.99±5.42 in hippocampal CA1 regionin,64.80±8.27,47.78±4.92,and 36.17±7.71 in hippocampal CA3 regionin,and 303.67±34.78,166.83±29.8,and 87.01±17.40 in hippocampal DG regionin.The levels of p-IKKα/β expression in LaCl₃ groups reduced significantly except for DG region of 0.25% LaCl₃ group(P<0.05).Intergrated density values(IDVs) of p-IκBα and p-NF-κBp65 protein expression in 0.25%,0.50% and 1.0% LaCl₃ groups were 0.58±0.06 and 0.46±0.06,0.49±0.07 and 0.36±0.08,and 0.36±0.09 and 0.25±0.08,which were significantly lower than those in the control group(0.68±0.05 and 0.56±0.08)(P<0.05).The expressions of p-IκBα and p-NF-κBp65 in the hippocampi were negatively correlated to the exposure dose of LaCl₃(r=-0.994,-0.978;P<0.05).Conclusion Subchronic LaC1₃ exposure lead to reduced NF-κB activity,and it may be one of the reasons of lower learning and memory ability resulted from lanthanum exposure.