早期环境对新生大鼠学习记忆能力与脑红蛋白的影响

The influence of early environment on neuroglobin levels, learning and memory

目的观察早期不同环境养育对大鼠学习记忆能力及脑红蛋白（Ngb）的影响。方法将45只新生雄性sD大鼠按随机数字表法分为丰富环境组、隔离环境组和正常对照组，每组大鼠15只。丰富环境组和隔离环境组于生后第1-28天分别接受早期丰富环境和隔离环境刺激，正常对照组常规饲养，3组大鼠均于生后第29天采用跳台试验评价大鼠学习记忆能力，并采用免疫组织化学方法测定大鼠Ngb表达情况。结果跳台试验结果显示，丰富环境组大鼠学习成绩和记忆成绩分别为（9．67±0．49）分和（9．80±0．56）分，明显高于正常对照组的（8．67±O．72）分和（8．93±1．10）分，而隔离环境组学习记忆成绩最低分别为（7．07±1．98）分和（7．67±0．98）分，3组大鼠各项评分组间比较，差异均有统计学意义（P〈0．05）；丰富环境组大鼠触电潜伏期为（166．33±36．08）s，与正常对照组（108．93±73．26）s比较，差异有统计学意义（P〈0．05），而隔离环境组大鼠触电潜伏期为（44．93±45．03）s，与丰富环境组和正常对照组比较，差异均有统计学意义（P〈0．05）。丰富环境组额叶皮质和海马Ngb的积分光密度（IOD）值分别为（224．56±89．09）和（127．70±28．16）；高于正常对照组的（141．33±45．10）和（92．69±28．52），差异有统计学意义（P〈0．05），而隔离环境组大鼠额叶皮质及海马Ngb的IOD值分别为（88．78±18．84）和（63．42±16．41），与丰富环境组和正常对照组比较，差异均有统计学意义（P〈0．05）。结论早期丰富环境刺激可提高大鼠的学习记忆能力，增加Ngb的表达；而隔离环境可减少Ngb的表达，使大鼠学习记忆能力受损。

Objective To explore the influence of environment early in life on learning and memory abilities and neuroglobin （Ngb） expression. Methods Forty-five newborn, male, Sprague-Dawley rats were randomly divided into an EE （enriched environment） group, an EI （isolated environment） group and a normal control group, with 15 rats in each group. The EE and EI group rats lived in those environments for their first 28 days of life. The step-down test was used to measure the rats＇learning and memory abilities on the 29th day. Ngb expression was exam- ined using immunohistoehemieal methods. Results The step-down test showed learning and memory scores for the EE group rats of （9.67 ± 0. 49） and （9.80 ± 0.56） respectively, significantly higher than those of the control group, （8.67 ± 0.72） and （8.93 ± 1.10）. The learning and memory abilities of the EI group were the lowest among the three groups, with scores of only （7.07 ± 1.98） and （7.67 ± 0.98 ） , respectively. The latency of the first electric shock was （ 166.33 ± 36.08 ） s in the EE group and significantly shorter than that in the control group （ 108.93 ± 73.26） s. The EI group showed the longest average latency （44.93 ± 45.03） s. Average Ngb expression as reflected by the integrated optical density in the EE group was （224.56 ± 89.09） in the frontal cortex and （127.70 ± 28.16） in the hippoeampus, a significant increase over expression in the control group. The Ngb expressions of the EI group were the lowest among the 3 groups-（88.78 ± 18.84） and （63.42 ± 16.41 ） in the frontal cortex and hippoeampus respectively. Conclusions Early exposure to an enriched environment can increase Ngb expression and improve learning and memory ability, but early isolation will reduce Ngb expression and learning and memory function.