ABSTRACT
Objective To study the influence of postnatal high protein feeding on learning and memory abilities of preterm rats.Methods After weaning,the SD offspring were divided into 6 groups randomly according random digits table:preterm standard protein group (group A),term standard protein group (group B),preterm low protein group (group C),term low protein group (group D),preterm high protein group (group E),and term high protein group (group F),with 34 rats in each group.Starting from 22 days of age,the standard protein group,low-protein group and the high-protein group were respectively fed with a standard protein diet (containing 18％ protein),low-protein diet (containing 8％ protein) and a high-protein diet (containing 30％ protein) until the end of experiment.Within each group,the rats were respectively tested in 6 weeks and 8 weeks.Morris water maze task was performed to assess the learning and memory abilities of the premature rats.Results 1.Directional navigation experiments:(1) At the age of 6 weeks,the escape latencies to find the platform were shortened with increased training times for full-term rats.The escape latencies of the premature rats did not change significantly on the third and fourth day of the experiment.(2) At the age of 8 weeks,the escape latencies to find the platform were shortened with increased training time for all of the rats.2.Probe trial test:(1)At the age of 6 weeks,premature rats spent significantly less time in target quadrant than full-time rats.And the percent age of traveled distance in target quadrant of premature rats was significantly less than full term rats (P ＜ 0.05).(2) At the age of 8 weeks,group E [(68.48 ± 20.65) s] spent significantly greater time in target quadrant than group A and group C [group A(52.41 ± 11.24) s,group C (49.54 ± 11.04) s].And the percent age of traveled distance in target quadrant of group E [(36.56 ± 10.44) ％] were significantly higher than group A and group C [group A (29.83 ± 8.33) ％,group C (26.97 ± 5.41) ％] (P ＜ 0.05).(3) At the age of 8 weeks,group E spent time in target quadrant and the percent of traveled distance in target quadrant [(68.48 ± 20.65) s,(36.56 ±10.44)％] were higher than group F [(61.29 ± 16.27) s,(35.71 ±6.61)％],but there was no significant difference (P ＞ 0.05).Conclusions In the early growth and development process of the brain,premature birth may seriously affect early brain functions in rats,and the learning and cognitive abilities of the premature rats are worse than full-term rats.In the subsequent process of growth and development,after a long time of high protein nutritional intake,the learning and cognitive abilities of the premature rats can be restored and they can catch up with full-term rats.