ABSTRACT
OBJECTIVE: To explore the effect of chronic stress during pregnancy on the learning and memory ability, amino acid neurotransmitters in hippocampus of offsprings and its mechanism. METHODS: The specific pathogen free adult Wistar rats were used. There were 10 rats each in female model group and control group, 10 rats in male mating model group and 5 in controlled mating group. A rat model of chronic stress during pregnancy of the female model group was established by the 21-day chronic unpredictable mild stress experiment. From the 3 rd day of the experiment, the model group and model mating group, control group and control mating group were caged separately.Blood was collected from the medial canthal vein from the rats on the day before stress and then on the 1 st, 7 th, and 14 th day after stress. Plasma corticosterone levels of maternal rats were determined by radioimmunoassay. Learning and memory responses of offsprings 42 days after birth were tested by Morris water maze and Y-maze. The levels of glutamate and γ-aminobutyric acid in hippocampus of offsprings were detected using enzyme linked immunosorbent assay. RESULTS: The plasma corticosterone level in maternal rats of model group was higher than that in control group at the same time points on the 7 th and 14 th day after stress(P<0.05). Compared with offsprings in the control group, the escaping latency of the model offsprings was prolonged(P<0.05). The training time needed to form correct memory increased(P<0.01), while the number of crossing platform and the correct response rate of memory retention test decreased(P<0.05), the level of glutamate in hippocampus decreased(P<0.01), and the level of γ-aminobutyric acid increased(P<0.01) in the model offsprings. The escape latency, the number of crossing platform, the training times and the correct response rate of model offsprings were associated with the plasma corticosterone levels of their mothers and amino acid neurotransmitters of offsprings(P<0.05). CONCLUSION: Chronic stress during pregnancy can reduce the learning and memory abilities of offsprings. The learning and memory ability was associated with the plasma corticosterone level of mother rats, the decrease of glutamate and the increase of γ-aminobutyric acid in the hippocampus.