Effect of Maternal Chronic Stress During Pregnancy on the Learning and Memory Ability and Hippocampal Cholinergic Neurotransmitter of Offspring Rats

Objective To observe the changes of learning and memory ability of offspring rats following maternal chronic stress during pregnancy,and study the possible mechanisms of injury related with hippocampal cholinergic neurotransmitter.

Methods A rat model was set up receiving chronic unpredictable mild stress (CUMS) during pregnancy.Plasma corticosterone levels of maternal rats were determined by radioimmunoassay.Learning and memory ability were tested using Morris water maze and Y-maze experiments.The levels of hippocampal cholinergic neurotransmitters were detected by ELISA for all experimental animals.The correlation between learning and memory ability and hippocampus cholinergic neurotransmitters was analyzed.

Results An elevation of the plasma corticosterone level was observed in the model rats (F=12.347,P=0.001),indicating stress state.The body weight of the model rats' offsprings was lower while the plasma corticosterone level was higher than the corresponding indicators of the control group's offsprings in postnatal day (PND)28 and PND 42(P<0.05).In terms of learning and memory ability,the escape latency of the model rats' offsprings was longer than that of the control group's offsprings (F=8.579,P<0.001).The times of crossing platform were fewer of the model rats' offspring than those of the control group's offspring (t=3.344,P=0.001).The times of required training was higher while the rate of correct response in model rats' offsprings was lower than that of the control group's offsprings (both Ps<0.05).Decreased Ach content and ChAT activity and elevated AchE activity of the model rats' offsprings were found,compared with the control group's offsprings (all Ps<0.05).There were correlations of learning and memory ability with plasma corticosterone and hippocampal cholinergic neurotransmitters of offspring rats (both Ps<0.05).

Conclusion The learning and memory ability is related to plasma corticosterone and hippocampal cholinergic neurotransmitter changes of offspring rats following maternal chronic stress treatment during pregnancy.