The Effect Of High-fat Diet On Lipid Metabolism And Spatial Learning And Memory In SD Rats

ObjectiveTo explore the effect of high fat diet on lipid metabolism and spatial learning andmemory in Sprague-Dawley (SD) rats at different life stages.MethodsTotal of10adult female SD rats were randomly divided into control diet (CTR)and high fat diet (HFD) groups, fed with lab chow and high fat diet (containing20%lard) throughout gestation and lactation periods respectively. The pups were weanedat four weeks of age, then half of the pups were continuously fed with the original diet,named continuing control (CTRc) and continuing high fat diet (HFDc) group, and theother half was transferred to the other diet, named turning high fat diet (CTRt) andturning to control diet (HFDt) group. Spatial learning memory performance wasconducted through Morris Water Maze (MWM) task in the pups at four and14weeksof age. After the MWM test, the pups were killed, the weights of body, brain, andvisceral fat were recorded, plasma was collected for leptin and lipids measuring.Results1. MWM test showed that at four weeks of age, the escape latency of rats inHFD group (104.78±4.45s,98.26±4.86s) was longer than that of in CTR group(85.93±5.96s,69.74±6.70s) on D1and D2in place navigation test (PNT); at14weeks of age, the escape latency of rats in HFDc group was longer than that of inother groups on first day and second day in PNT. At four weeks of age, the firsttrial escape latency of rats was longer in the HFD group (115.41±2.73s) on D2inPNT than that in CTR group (69.74±6.70s), and at14weeks of age, the escapelatency of rats was longer in the HFDc groups (76.04±16.19s) than those in othergroups (30.89±11.18s,29.42±11.66s and23.79±5.18s).2. The weighing results showed that at four weeks of age, the body weight, andthe mass of liver, fat and the whole brain of HFD group rats (90.05±6.71g,3.73±0.18g,0.41±0.12g and1.50±0.07g) were larger than those of CTR group rats (70.60±17.30g,2.87±0.83g,0.22±0.07g and1.32±0.12g)(P=0.01, P=0.01, P=0.00and P=0.00); at14weeks of age, the mass of rat whole brain in HFDc and HFDt groups (1.64±0.08g,1.74±0.10g) were less than those in CTRc group (1.88±0.11g)(P<0.05).3. The results of biochemical indicators: at four weeks of age, the level of plasmatriglycericle (0.83±0.24mmol/L) was higher in the rats of HFD group than thatof CTR group (0.45±0.21mmol/L), and the levels of plasma high density lipoproteincholesterol (0.26±0.09mmol/L) and leptin (1.16±0.06μg/L) were lower than that ofCTR group rats (0.50±0.03mmol/L,1.26±0.08mmol/L)(P<0.05); at14weeks ofage, the level of plasma total cholesterol and low density lipoprotein cholesterol(1.52±0.52mmol/L,0.11±0.04mmol/L) were higher in the rats of HFDc group thanthat of CTRc group rats (0.99±0.14mmol/L,0.07±0.01mmol/L)(P<0.05), and thelevel of plasma leptin in CTRc group rats (1.13±0.06μg/L) was higher than those ofother groups (1.06±0.05μg/L,1.04±0.04μg/L and1.04±0.06μg/L)(P<0.05).ConclusionsAccording to this study, the perinatal HFD could result in dyslipidemia, impactthe development of brain, lower the plasma leptin level and influence the spatiallearning and memory performence in rat pups at four weeks of age, and the effect onbrain, leptin, and spatial learning ability could last to adult age. The HFD afterweaning may have harmful impact on lipid metabolism and spatial memory ability inadult rats.Reduced brain mass and plasma leptin level in the rat pups might be theconsequence of perinatal HFD..