OBJECTIVETo explore the effect of maternal cypermethrin exposure during lactation on learning and memory ability in adult female offspring, as well as the possible mechanism.

METHODSTwelve maternal mice were randomly divided into 6.25 mg/kg cypermethrin, 25.0 mg/kg cypermethrin and control groups (four dams each group, ten pups each dam, half male half female, twenty female pups each group). Maternal mice were orally administered with different doses of cypermethrin (6.25 and 25 mg/kg/d) once daily from postnatal day1 (PND1) to PND21. Maternal mice in control group were treated with corn oil. The learning and memory ability of female offspring were observed by using water labyrinth task for continuously seven days on PND60. All the female offspring were killed and the brain and hippocampus were detached after the test. The expression level of NMDA receptor NR1 protein in hippocampus was detected by Western-blotting.

RESULTSThere were no statistically significant in the difference in weight of body and brain among three groups (P > 0.05). Through the Repeated one way ANOVA, the learning time of latency in the 25.0 mg/kg cypermethrin group [(31.3 ± 17.0) s] were significantly longer than that in the control group [(21.0 ± 14.0) s] (P < 0.05). The memory time of latency in the 25.0 mg/kg cypermethrin group [(24.6 ± 21.1) s] were significantly longer than that in the control group [(14.1 ± 16.3) s] (P < 0.05). However, the difference of the wrong number among groups was not statistically significant in the test (P > 0.05).

CONCLUSIONMaternal cypermethrin exposure during lactation disturbs learning and memory ability in adult female offspring in a degree, which maybe caused by the reduction of protein level of hippocampus NR1.