Effect and mechanism of formaldehyde on learning and memory ability in ICR mice

  Objective  To explore the effect and mechanism of formaldehyde (FA) on learning and memory ability in aged ICR mice.

  Methods  Thirty 14-month ICR mice (half male and half female) were randomly divided into 3 groups (10 in each group): low dose (50 mg/kg) and high dose (100 mg/kg) FA groups and a blank control group (normal saline). The treatments were administered through gavage once a day continuously for 6 weeks. Spatial learning and memory ability of the aged ICR mice were assessed with Morris water maze test. Contents of malondialdehyde (MDA), glutathione (GSH), and class III alcohol dehydrogenase 3 (ADH3) in brain tissues of the mice were measured with kit assays. The neuron-specific nuclear protein (NeuN) in brain tissues of the mice were detected with immunohistochemical method and expressions of nuclear factor-erythroid 2-related factor-2 (Nrf2) and heme oxygenase 1 (Ho-1) were determined with Western blot.

  Results  Compared to those in the control mice, significantly increased escape latency and decreased times of crossing the platform were observed in the FA treated mice. The mice treated with low dose FA had decreased learning and memory ability in comparison with the control mice. In brain tissues of the mice with low dose FA treatment, significantly increased MDA (31 nmol/L), decreased GSH (32.65 μmol/L) and ADH3 (6.27 ng/l) were detected in the low dose FA treated mice compared to those in the control mice. The NeuN expression in brain tissues of low dose FA treated mice was 38.7% lower than that of the control mice group.

  Conclusion  Long-term exposure to formaldehyde may cause impairment of learning and memory ability in aged ICR mice and the mechanism of the effect may be related to up-regulated oxidative stress response and neuron damage.