Intervention effect of HSP60 on learning and memory impairment induced by combined exposure to lead and hypertension in mice
Objective To investigate the intervention effect of heat shock protein 60(HSP60)on learning and memory impairment induced by combined exposure to lead and hypertension in mice,and the relative mechanism of triggering receptor expressed on myeloid cells 2(TREM2).Methods Specific pathogen-free C57BL/6J male mice were randomly divided into control group,hypertension group,lead-exposed group and lead-exposed+hypertension group,or into control group,heat shock protein 60(HSP60)control group,lead-exposed+hypertension group and HSP60 intervention group,with 10 mice in each group.Mice of hypertension group and lead-exposed+hypertension group were intraperitoneally injected with angiotensinⅡ at a dose of 0.5 mg/(kg·d)for seven consecutive days to induce hypertension model.Mice of the lead-exposed group,lead-exposed+hypertension group,and HSP60 intervention group were given lead acetate drinking water with a mass concentration of 250.0 mg/L,while mice in the control group,hypertension group,and HSP60 control group were given purified water for 12 weeks.Mice of the HSP60 control group and HSP60 intervention group were intraperitoneally injected with a solution of HSP60 at a dose of 4 mg/kg body weight,every other day for a total of three times at the 12th week.The learning and memory ability of mice was detected using the Morris water maze test.The enzyme-linked immunosorbent assay was used to detect the levels of interleukin(IL)-1 β,IL-6 and tumor necrosis factor-α(TNF-α)in the hippocampal tissues of the mice.The relative expression of ionized calcium binding adaptor molecule-1(IBA1)and TREM2 protein in the hippocampus of mice was detected using Western blot.Results i)The number of platform crossings of the mice in the hypertension group and the lead-exposed group was lower than that in the control group(both P＜0.05).The escape latency of the mice on the third day was longer and the number of platform crossings was lower in the lead-exposed+hypertension group compared with the control group,hypertension group and lead-exposed group(all P＜0.05).The levels of IL-1β,IL-6,and TNF-α in the hippocampus of the other three groups increased compared with the control group(all P＜0.05).The relative expression of IBA1 protein in the hippocampus of lead-exposed group and lead-exposed+hypertension group increased(all P＜0.05),while the relative protein expression of TREM2 decreased compared with the control group(all P＜0.05).The levels of IL-1β,IL-6,TNF-α,and the relative protein expression of IBA1 protein in the hippocampus of the lead-exposed+hypertension group were higher(all P＜0.05),and relative expression of TREM2 protein was lower(P＜0.05)than those in the hypertension group.The level of TNF-αand the relative expression of IBA1 protein in the hippocampus of lead-exposed+hypertension group were higher than those in lead-exposed group(all P＜0.05).ii)The escape latency of mice in the lead-exposed+hypertension group was longer than that in the control group(P＜0.05),and the number of platform crossings was fewer than that in the control group(P＜0.05).The escape latency of mice in the HSP60 intervention group was shortened(P＜0.05),the number of platform crossings increased(P＜0.05),and the levels of IL-1β,IL-6,TNF-α and relative expression of IBA1 protein decreased in the hippocampus(all P＜0.05),while the relative expression of TREM2 protein increased(P＜0.05)compared with the lead-exposed+hypertension group.Conclusion Combined exposure of lead and hypertension has a synergistic effect on learning and memory impairment in mice.The mechanism may be related to the inhibition of TREM2 expression by lead in the hippocampus of hypertensive mice and aggravating the neuroinflammatory response.Intervention with TREM2 receptor agonist HSP60 can alleviate learning and memory impairment in mice exposed to lead and hypertension by up-regulating TREM2 expression in the hippocampus.
LeadHypertensionTriggering receptor expressed on myeloid cells 2Learning and memory functionHeat shock protein 60HippocampusMice
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