Effects Of Different Dietary Fatty Acids Composition On Brain Glucose Metabolism And Development Of Related Blended Oil

[Objective] The study aims to explore the effects of different dietary fatty acids composition on brain function of rats from the view of glucose metabolism,and further develop the associated blending oil.The results can provide some theoretical basis for practical application.[Method] Sixty cleaning male SD rats aged 21 days old were selected.After adaptive feeding for 7days,the rats were randomly divided into 6 groups: normal control(7% SO)group(SO,soybean oil;standard AIN 93 G feed),15%SO group(AIN 93 G feed added with 15% soybean oil),15%PO group(PO,pork oil;AIN 93 G feed added with 15% PO),15%OO group(OO,olive oil;AIN 93 G feed with added15% olive oil),15%FO group(FO,fish oil;AIN 93 G feed added with 15% fish oil),1:1 SO:FO group(SO:FO,soybean oil and fish oil;AIN 93 G feed added with 7.5% soybean oil and 7.5% fish oil).There were 10 rats in each group,and the experment lasted for 13 weeks.During the experiment,the food intake of the rats was monitored every 2 days.The weight of the rats was monitored every week,and the blood glucose(Blood glucose,Glu)levels of rats were measured by centrifugation after blood collection from the lower orbital of rats every 4 weeks.At the end of the experiment,the serum lipid related indexes[triglyceride(TG),total cholesterol(T-CHO),low density lipoprotein cholesterol(LDL-C),high density lipoprotein cholesterol(HDL-C)were all explored.At the 13 th week,the shuttle test was conducted.At the end of the experiment,H-E staining was used to observe the pathological changes of hippocampus.Apoptosis rates of the hippocampus in rats were determined by TUNEL method.Immunohistochemistry method was used to detect the expression of synaptophysin in hippocampus.The glucose content,enzyme activities of hexokinase(HK),fructose-6-phosphate kinase(PFK),pyruvate kinase(PK),and content of6-phosphate dehydrogenase(G-6-PDH)in brain tissue of rats were also measured.The quantitative real-time polymerase chain reaction(q RT-PCR)method was used to detect the gene expression of insulin signal pathway which contained insulin receptor(Insr),insulin receptor substrates 1(Irs1),aphosphoinositide 3-kinase(PI3K),protein kinase B(Akt2),mammalian target of rapamycin(m TOR),glucose transporters-1(GLUT-1),and glucose transporters-3(GLUT-3)in the hippocampus of rats.Finally,according to the experimental results,the related blending oil was prepared.[Results](1)Compared with the control group,the weight of rats in the 15% PO group and the15%FO group decreased significantly(P < 0.05)at the 4th week,and there were no significant differences among other groups.At the 6th week,the weight of rats in 15%SO group,15%PO group decreased significantly(P < 0.05),and there were no significant differences among other groups.Compared with the control group,the food intake of 15% FO group decreased significantly(P < 0.05)at 2 w;the food intake of each high fat group decreased significantly(P < 0.05)at 4 w,the food intake of 15% PO group decreased significantly(P < 0.05)at 6 w,and the average food intake of 15% FO group increased significantly(P < 0.05)at 10 w.At the end of the experiment,there were no significant differences in body weight and average food intake.Shuttle experiment showed that the latency of passive avoidance in 1:1SO: FO group was significantly lower than that in other groups(P < 0.05).(2)Compared with the control group,the blood glucose level of 1:1 SO:FO group increased significantly at 4 w,and was also significantly higher than other high fat groups(P < 0.05);At the 8th week,there were no significant differences in blood glucose levels among the groups.At the end of the experiment,compared with the control group,the blood glucose levels of 15%PO group,15%FO group and 1:1 SO:FO group were all significantly reduced,and the blood glucose levels of the above three groups were lower than that of 15%SO group(P < 0.05).At the end of the experiment,compared with 15%SO group,TG level in 15%FO group decreased significantly(P < 0.05),and there were no significant differences among the other groups.Compared with the control group,the levels of T-CHO in 15%FO group and 1:1 SO:FO group decreased significantly(P <0.05).LDL-C levels in 15%OO group,15%FO group and 1:1 SO:FO group were significantly lower than those in control,15%SO group and 15%PO group(P < 0.05).Compared with control group,HDL-C level in 15%OO group increased significantly(P < 0.05).(3)Compared with the control group,the apoptosis rates of nerve cells in 15%PO group and 15%OO group decreased significantly(P < 0.05),and the apoptosis rates of nerve cells in the above two groups were significantly lower than those in the 15%SO group and 1:1 SO:FO group(P < 0.05).Compared with the control group,the average optical density of synaptophysin in hippocampus of 15%FO group was significantly decreased(P < 0.05).(4)Compared with the control group,there were no significant differences in glucose content of hippocampus of rats in each group,but glucose content in cortex of 1:1 SO:FO group was significantly increased compared with 15% SO group(P < 0.05).Compared with the control group,the HK activity in the 15%PO group was significantly decreased(P < 0.05),while other enzyme activities were not significantly different.Compared with the control group,the expressions of Insr in 15%OO group and 1:1 SO:FO group were significantly increased(P < 0.05).The expressions of Irs1,PI3 K,and m TOR had no significant differences among all the groups(P > 0.05).Compared with the control group,the expression of m TOR in15% OO group was significantly higher(P < 0.05).There was no significant difference in the expression of GLUT-1 among all the groups(P > 0.05).Compared with the control group,the expression of GLUT-3in 15% OO group was significantly up-regulated(P < 0.05),and it was significantly higher than other high-fat groups(P < 0.05).(5)According to the proportion of 45% olive oil,45% soybean oil,8% linseed oil and 2% capsule fish oil,a nutritional blended oil was prepared.It was tested to be in line with the dietary fatty acid recommendations of the Chinese Nutrition Society in 2000: n-6 PUFA:n-3 PUFA=(4~6):1,and the requirements on fatty acid balance of Dietary Nutrient Reference Intake for Chinese Residents in 2013.The nutritional indexes in the blended oil were as follows: squalene(2.18 mg/kg),β-carotene(0.474mg/kg),α-tocopherol(73.6 mg/kg),γ-tocopherol(132 mg/kg),δ-tocopherol(20.4 mg/kg),and total sterol(5700 mg/kg).[Conclusion] Different dietary fatty acid composition can affect the body’s blood lipid,blood glucose and cerebral glucose metabolism to some extent,among which n-6/n-3 1:1 fatty acid composition can reduce the latency of passive escape in rats;a certain amount of monounsaturated fatty acid,n-3polyunsaturated fatty acid and n-6/n-3 1:1 fatty acid composition can improve blood glucose and blood lipid levels;monounsaturated fatty acids can reduce the apoptosis rate of hippocampal cells;excessive supplement of fish oil,which is mainly composed of n-3 polyunsaturated fatty acids,leads to the decrease of synaptophysin expression;monounsaturated fatty acid and n-6/n-3 1:1 fatty acid have the effects of improving cerebral glucose metabolism.Olive oil,linseed oil and soybean oil were taken as base oils,and a proper amount of fish oil was added to prepare a blended oil.The ratio of the blended oil was: soybean oil: linseed oil: fish oil = 45%: 45%: 8%: 2%.The oil meets the requirements of the dietary fatty acid recommendations of the Chinese Nutrition Society: n-6 PUFA: n-3 PUFA=(4~6):1,and the requirements on fatty acid balance in the Dietary Nutrient Reference Intake for Chinese Residents.