复合微量营养素对幼鼠学习记忆能力及脑海马CA3超微结构的影响

目的研究复合微量营养素对幼年大鼠学习记忆能力的影响及其机制。方法5周龄雄性SD大鼠40只,按体重随机分成3个实验组和1个对照组。实验组分别以低、中、高剂量复合微量营养素水悬液灌胃,对照组用安慰剂水悬液灌胃。30天后各组大鼠每隔1天在穿梭箱中进行双向回避实验训练,连续训练4次后,停止训练,并在14天内分2次测定其记忆消退情况;用电镜观察海马CA3区突触结构的变化;用免疫组织化学方法检测大鼠海马突触素(Syn)的免疫表达。结果高剂量组大鼠电击逃避时间长于对照组(P<0.05);高剂量组大鼠脑海马CA3区突触数量、突触后致密物质厚度、突触界面曲率、Syn免疫反应阳性产物吸光度均显著高于对照组(P<0.05);电击逃避时间和突触界面曲率呈剂量效应关系。结论复合微量营养素能通过提高大鼠脑海马的突触可塑性来改善幼年大鼠学习记忆能力。

Effect of multiple-micronutrient supplementation on learning and memorizing ability of young rats and the ultra-structure in CA3 region of hippocampus of rat' s brain

Objective To study the effects of multiple-micronutrient on the learning and memory ability of young rats using shuttle-box,as well as to observe the ultra-structure and the synaptophysin(SYN) immunoreactive expression in the region of hippocampal CA3.Methods Forty 5-weeks old male Sprague-Dawley rats were randomized divided into control group and 3 test groups by body weight. Rats were injected intraperitoneally with multiple-micronutrient [0g/(kg·d),0.74g/(kg·d),1.48g/(kg·d)and 2.22g/(kg·d)] once per day for 30 days.Active avoidance behayior of learning and memory performance in different groups were measured by shuttle-box.The immune expression of Syn in the region of hippoeampal CA3 were tested with immunohistochemical method.Moreover,ultrastructural pathologic features of the CA3 region of hippocampus were investigated by transmission electron microscope. Results The shuttle-box test showed that the time of escape reaction of high-dose group (13.15±8.106,9.50±5.063)was longer(P<0.05) than that of control group.The results revealed a significant increase in the number of synapses,the thickness of postsynaptic density,synaptic curvature and the absorbency of positive product of Syn immunoreaction in the region of hippocampal CA3 in high-dose group compared with control group,which were significant difference(P<0.05). Conclusion Our study suggests that synaptic plasticity might be the probable mechanism on improving the learning and memory ability by multiple-micronutrient in young rats.