Effects Of Thiamin, Riboflavin And Nicotinamide Energy Metabolism And Learning And Memory Ability In High-Fat Diet Induced Obese Rats

Objective:Thiamin, riboflavin and nicotinamide participate in glucose, lipid and protein metabolism in form of coenzyme. In order to observe the effects of high-dose thiamin and nicotinamide on blood lipid, energy metabolism and learning and memory ability in high-fat diet induced obese rats.Methods:In this study,96healthy male Sprague-Dawley rats were exposed to gavage thiamin, riboflavin or nicotinamide either along or in combination for15weeks using2×2X2factorial design. All the rats were divided into8groups randomly (each group n=12): high-fat model (FO), fat+thiamin (F1), fat+riboflavin (F2), fat+nicotinamide (F3), fat+thiamin+riboflavin (F4), fat+thiamin+nicotinamide (F5), fat+riboflavin+nicotinamide(F6), fat+thiamin+riboflavin+nicotinamide(F7).All the rats were fed with high-fat diets. The rats in the control group were fed normal diet. After12weeks spatial learning and memory ability was evaluated by CTA and Morris water maze. In the end of the experiment, blood serum were collected to determine blood lipid and erythrocyte metabolic enzymes were collected before and after interference.Results:After19weeks, compared with normal control group, the body weight of high-fat induced rats was increased by15.7%; compared with high-fat control group, the body weight dropped35.0%,30.0%,30.1%and30.6%respectively in fat+nicotinamide, fat+thiamin+nicotinamide, fat+riboflavin+nicotinamide and fat+thiamin+riboflavin+nicotinamide group (P<0.05); compared with normal control group, the body weight even dropped22.8%,17.0%,17.0%and17.7%respectively (P<0.05); however the body weight of the rats of thiamin and/or riboflavin administration was not significantly increased or decreased (P>0.05). Cholesterol (CHOL) and low-density lipoprotein (LDL-C) in the experimental groups(in addition to the thiamin group) were significantly lower than in the high-fat control group; however, LDL-C/HDL-C was0.29,0.26,0.25and0.26respectively in F3, F5, F6and F7group, and it was significantly lower than that in the high-fat control group (P<0.05). Compared with group F0, erythrocyte transketolase activity coefficientin(ETKAC) in group C was decreased86.55%, and activity of Na+-K+-ATPase was increased40.54%; ETKAC in the F1-F7group were significantly decreased87.89%,80.27%,95.07%,84.16%,86.25%,82.66%and83.56%; activities of Na+-K+-ATPase in the F1-F5were increased49.55%,51.84%,121.17%,47.14%and57.84%(P<0.05). Compared with group F0, activities of malate dehydrogenase (MDH) and pyruvate kinase (PK) in group C was increased28.11%and39.09%; activities of succinatedehydrogenase (SDH) in the F1-F7group were significantly increased28.24%,26.72%,32.78%,27.57%,39.41%,37.14%and33.58%; activities of PK in the F1, F3, F5and F7group were increased47.70%,59.35%,49.39%and61.04%(P<0.05). Mitochondrial membrane potential (0.75(0.51,0.92)) in the high-fat induced rats was the lowest. Compared with group F0, mitochondrial membrane potential in group C was increased33.33%, in the F1-F5group were increased26.67%,26.67%,26.67%,24.00%and26.67%(P<0.05). CTA: The aversion index (80.00(71.40,85.70)) in the high-fat induced rats was the lowest; the aversion index in the thiamin administration group and normal control group were not significantly increased compared with high-fat control group(P>0.05); the aversion index in the other administration group was lower markedly than that in the high-fat control group, and the difference was significant (32.14%,38.04%,44.75%,48.08%,34.54%,26.50%, P<0.05). Positioning navigation test:at1d and2d, there was no significant difference in the escape latencies of nine groups, while at3d,4d and5d, the escape latencies of the high-fat control group were significantly longer compared with normal control group (P<0.05). The escape latencies in thiamin and/or riboflavin and/or nicotinamide administration group were significantly lower than those of the high-fat control group (P<0.05). Spatial probe test: length of stay in the quadrant of the original platform and the number of crossing times through the original platform in the high-fat control group were decreased obviously compared with that of normal group, and the time to platform(escape latency) was obviously increased(P<0.05); length of stay in the quadrant of the original platform and the number of crossing times through the original platform in the thiamin and/or riboflavin and/or nicotinamide administration group were increased obviously compared with that of the high-fat control group and the time to platform was obviously decreased (P<0.05).Conclusion:High-dose nicotinamide can effectively control the body weight gain of obese rats, however, no significant influence in the thiamin and/or riboflavin group. Thiamin, riboflavin and nicotinamide participate in glucose, lipid and protein metabolism in form of coenzyme. Through energy metabolism and lipid metabolism, potential of mitochondrial membrane in high-fat diet induced obese rats can be improved, so that the nerve cell death is reduced, in order to maintain synaptic plasticity in hippocampus, prevent the destruction of the hippocampal formation, improve the taste and spatial learning and memory ability of high-fat induced rats.