Mechanisms Of Polyunsaturated Fatty Acid-mediated Development In Spatial Memory Of Developing Rats

In order to investigate the effect of dieting the optimal dosage of DHA, safflower seed oil, walnut oil, perilla oil, α-linoleic acid on the developing rats’ spatial learning and memory and its molecular mechanism. A total of 56 male SD rats in weaning period were randomly divided into seven groups : negative control group, essential fatty acid deficiency contro l group, DHA group(300mg/kg·d), α-linoleic acid group(1.32g/kg·d), perilla oil group(2.45 m L/kg·d), walnut oil group(2.45 m L/kg·d) and safflower seed oil group(1.65g/kg·d). After continuously fed with the method of gavage every day for eight weeks, rats were used to test the the changes in the spatial learning and memory by Morris water maze test for a start. Then we extracted the cerebral cytomembrane of rats and tested the types and the content of fatty acids in cerebral cytomembrane by gas chromatogra phy. Next, real-time PCR was used to test the m RNA expression of immediate early gene(c-fos), c AMP responsive element binding protein(CERB) and N-methyl-D-aspartate receptor subunit(NR1) in hippocampus of rats. In the meanwhile, western-bolt was used to detect the protein expression of CREB and c-Fos in hippocampus of rats. At last, we constructed the cell model by culturing the hippocampal cells and divided them into negative control group, DHA group, α-linoleic acid group, perilla seed oil group, walnut oil group and safflower oil group. After 24 h, we observed the changes of the hippocampal cells and used real-time PCR to detect the m RNA expression of c-fos, CERB and NR1 in hippocampal cells.The results showed that:(1) Compared with the negative control group, the rats’ escaping latency of DHA, perilla oil, α-linoleic acid, walnut oil and safflower seed oil groups was significantly shortened(P<0.05 and P<0.01) and the target quadrant time ratio significantly increased(P<0.05 and P<0.01). DHA, perilla oil, walnut oil and safflower seed oil groups exhibited significantly better performances in the number of annulus crossings(P<0.05) and α-linoleic acid group did not show obvious difference in the number of annulus crossings than the negative control group. There were no obvious differences between essent ial fatty acid deficiency control group and negative control group in the results of Morris water maze test.(2) Compared with the negative control group, the types of fatty acids in rats’ cerebral cytomembrane of every groups were same; the n-3 polyunsaturated fatty acids and the ratio of n-3PUFA/ n-6PUFA in rats’ cerebral cytomembrane of DHA, perilla oil, α-linoleic acid, walnut oil and safflower seed oil groups obviously increased(P<0.05 and P<0.01); the DHA group, walnut oil group and safflower seed oil group showed a significant increase in the ratio of DHA/AA in rats’ cerebral cytomembrane(P<0.05 and P<0.01). There were no significant differences between essential fatty acid deficiency control group and negative control group in the content of fatty acids in cerebral cytomembrane of rats.(3) Compared with the negative control group, the m RNA expression of c-fos, CERB and NR1 in rats’ hippocampus of DHA, perilla oil, α-linoleic acid, walnut oil and safflower seed oil groups obviously increased(P<0.05 and P<0.01); the protein expression of CREB and c-Fos in rats’ hippocampus of DHA, perilla oil, α-linoleic acid, walnut oil and safflower seed oil groups obviously increased(P<0.05 and P<0.01). The essential fatty acid deficiency control group did not show obvious differences in the expression of gene and protein.(4) Compared with the negative control group, the m RNA expression of c-fos, CERB and NR1 in hippocampal cells of DHA, perilla oil, α-linoleic acid, walnut oil and safflower seed oil groups significantly increased(P<0.05).The conclusion showed that:(1) Dieting the optimal dosage of DHA and perilla oil belonging to n-3PUFA, walnut oil, safflower seed oil and α-linoleic acid belonging to n-6PUFA can improve the spatial learning and memory of developing rats. But, different oils have different effects. The short-term lake of essential fatty acid has no effect on the spatial learning and memory of developing rats.(2) DHA, perilla oil, safflower seed oil, walnut oil and α-linoleic acid may enhance the spatial learning and memory of rats by increasing the content of n-3PUFA and ratio of n-3PUFA/n-6PUFA in cerebral cytomembrane of rats.(3) DHA, perilla oil, safflower seed oil, walnut oil and α-linoleic acid may improve the spatial learning and memory of rats by promoting the generation of long-term potentiation by means of regulating the m RNA expression of c-fos, CERB, NR1 and the protein expression of CREB and c-Fos in rats’ hippocampus.