Development of dietary obesity in rats: influence of amount and composition of dietary fat.

This study was conducted to examine long-term effects of amount and type of dietary fat on body weight and body composition. Adult male Wistar rats were fed high fat (HF; 60% of calories) or low fat (LF; 20% of calories) diets for 28 weeks. Half of the rats in each condition received diets with saturated fat (lard) (S) and the remainder received diets with polyunsaturated fat (corn oil) (U). From 28-39 weeks, HF rats were switched to LF diets (fat type remained constant). From 40-50 weeks, previously HF fed rats were weight-matched to rats in the LF fed groups. HF rats became fatter than LF rats during weeks 1-28 and remained heavier and fatter from weeks 28-39. During weeks 1-28, type of dietary fat had no effect on total body fat in either HF or LF rats, but during period 2 (weeks 28-39), U rats were heavier and fatter than S rats. There was some indication that U diets were associated with greater accumulation of fat in subcutaneous adipose tissue depots than S diets. From 40-50 weeks, rats previously fed the HF diet required less food to maintain their body weight than did LF diet rats. In summary, these results suggest that although both amount and type of dietary fat can affect body weight and body composition, the effects of the type of fat are less than those of amount of dietary fat.     

Effects of introducing physical training in the course of a 16-week high-fat diet regimen on hepatic steatosis, adipose tissue fat accumulation, and plasma lipid profile

OBJECTIVE: We recently reported that an 8-week high-fat diet-induced hepatic steatosis was completely prevented if an exercise training programme was introduced and pursued concurrently with the diet. The purpose of the present study was to determine the extent to which introducing exercise training at mid-point in the course of a 16-week high-fat diet regimen contributes to the reversal of liver lipid infiltration and the reduction of blood lipid profile deterioration and body fat accumulation. DESIGN AND SUBJECTS: Two groups of rats were fed a high-fat diet (42% kcal) for 16 weeks, one remaining sedentary during this entire period (HF-Sed) and the other being exercise trained for the last 8 weeks (HF-Tr). A third group was fed a standard diet and remained sedentary for all 16 weeks (SD-Sed). Training (5 days/week for 8 weeks) began 8 weeks after introducing the high-fat diet and consisted of treadmill running that was progressively increased to reach 60 min at 26 m/min, 10% grade, for the last 4 weeks. MEASUREMENTS: Various parameters including liver lipid infiltration, fat depots and blood lipids. RESULTS: Unexpectedly, liver lipid infiltration was not significantly higher in HF-Sed than in SD-Sed rats (means+/-s.e.: 14.9+/-1.7 vs 12.3+/-0.4 mg/g; P>0.05). High-fat compared to age-matched standard fed rats also showed an absence of difference (P>0.05) in the weight of total visceral fat pads (13%), plasma nonesterified fatty acids (NEFA), and leptin concentrations, but depicted significantly (P<0.01) higher values for subcutaneous fat pad weight and plasma triacyglycerol. Exercise training largely decreased visceral and subcutaneous fat accumulation by 30 and 26%, respectively (P<0.01) as well as NEFA, triacylglycerol, and leptin concentrations (P<0.01). CONCLUSION: Liver lipid infiltration does not seem to progress linearly over 16 weeks of high-fat feeding in light of what has previously been observed after 8 weeks of high-fat feeding. Introducing a training programme in the course of a 16-week high-fat diet protocol reduced adiposity, plasma NEFA, and leptin concentrations below the levels observed in standard fed rats. These data indicate that, exercise training, whether conducted concurrently or introduced during the course of a high-fat diet, is an asset to reduce the deleterious effects of a high-fat diet.     

Different origin of hypertriglyceridemia induced by a high-fat and a high-sucrose diet in ventromedial hypothalamic-lesioned obese and normal rats

OBJECTIVE: To clarify the mechanism by which plasma triacylglycerol is affected by a high fat or a sucrose diet. DESIGN: Two sets of six groups each having six rats were prepared-(1) ventromedial hypothalamic (VMH)-lesioned rats fed a standard diet; (2) sham VMH-lesioned rats fed a standard diet; (3) VMH-lesioned rats fed a high-fat diet; (4) sham VMH-lesioned rats fed a high-fat diet; (5) VMH-lesioned rats fed a high-sucrose diet; and (6) sham VMH-lesioned rats fed a high-sucrose diet. After VMH lesions and sham operations, the rats were provided standard, high-fat and high sucrose diets for 2 weeks. Two weeks later, blood samples were collected after overnight fast to determine plasma triacylglycerol (TAG), hepatic triacylglycerol secretion rate (TGSR), fractional catabolic rate (FCR) of triacylglycerol and postheparin plasma lipoprotein lipase (LPL), plasma glucose, insulin and leptin. RESULTS: Values of TAG, TGSR, FCR and LPL in VMH-lesioned obese rats were all greater than those in sham-operated rats, regardless of the diet fed. In sham-operated rats, high-fat diet fed rats showed higher TAG with similar TGSR, higher LPL and lower FCR than those of standard diet fed rats. High-sucrose diet fed rats showed significantly higher TAG with higher TGSR, higher LPL and lower FCR than those of standard diet fed rats. Moreover, high-sucrose diet fed rats showed higher TAG with higher TGSR, lower LPL and higher FCR than those of high-fat diet fed rats. In VMH-lesioned rats, high-fat diet fed rats showed higher TAG with similar TGSR, higher LPL and lower FCR than those of standard diet fed rats. High-sucrose diet fed rats showed markedly higher TAG with notably higher TGSR, higher LPL and lower FCR than those of standard diet fed rats. High-sucrose diet fed rats showed still higher TAG with markedly higher TGSR, similar LPL and higher FCR than those of high-fat diet fed rats. CONCLUSIONS: The mechanism by which TAG metabolism is affected by a high-fat or a high-sucrose diet differed; a high-fat diet increased plasma TAG level by lowering removal of TAG without increase in hepatic TAG secretion in sham-operated (normal) rats. A high-sucrose diet, in contrast, induced much higher plasma TAG levels by both increased hepatic TAG secretion and decreased removal of TAG. The effects of a high-fat or a high-sucrose diet were similar but exaggerated in VMH lesioned animals.     

Dietary supplementation of tetradecylthioacetic acid increases feed intake but reduces body weight gain and adipose depot sizes in rats fed on high-fat diets

Aim: The pan-peroxisome proliferator-activated receptor (PPAR) ligand and fatty acid analogue tetradecylthioacetic acid (TTA) may reduce plasma lipids and enhance hepatic lipid metabolism, as well as reduce adipose tissue sizes in rats fed on high-fat diets. This study further explores the effects of TTA on weight gain, feed intake and adipose tissue functions in rats that are fed a high-fat diet for 7 weeks.
Methods: The effects on feed intake and body weight during 7 weeks' dietary supplement with TTA (∼200 mg/kg bw) were studied in male Wistar rats fed on a lard-based diet containing ∼40% energy from fat. Adipose tissue mass, body composition and expression of relevant genes in fat depots and liver were measured at the end of the feeding.
Results: Despite higher feed intake during the final 2 weeks of the study, rats fed on TTA gained less body weight than lard-fed rats and had markedly decreased subcutaneous, epididymal, perirenal and mesenteric adipose depots. The effects of TTA feeding with reduced body weight gain and energy efficiency (weight gain/feed intake) started between day 10 and 13. Body contents of fat, protein and water were reduced after feeding lard plus TTA, with a stronger decrease in fat relative to protein. Plasma lipids, including Non-Esterified Fatty Acids (NEFA), were significantly reduced, whereas fatty acid β-oxidation in liver and heart was enhanced in lard plus TTA-fed rats. Hepatic UCP3 was expressed ectopically both at protein and mRNA level (>1900-fold), whereas Ucp1 mRNA was increased ∼30-fold in epididymal and ∼90-fold in mesenteric fat after lard plus TTA feeding.
Conclusion: Our data support the hypothesis that TTA feeding may increase hepatic fatty acid β-oxidation, and thereby reduce the size of adipose tissues. The functional importance of ectopic hepatic UCP3 is unknown, but might be associated with enhanced energy expenditure and thus the reduced feed efficiency.     

Fatty liver in rats induced by excessive intake of a nutritionally adequate liquid diet

In order to test whether or not overeating of a nutritionally adequate diet with reasonable fat content could result in significant fat accumulation in the liver, male Sprague-Dawley rats were provided with free access to either a nutritionally adequate liquid diet with 35 per cent of calories as fat or a regular diet (controls) for 3 months. After the feeding period, body weight, Lee index, and epididymal adipose tissue weight, were significantly greater in rats fed with the liquid diet than in the controls. Liver weight, hepatic triglyceride levels were also greater in the liquid diet group. Histologically, remarkable fatty infiltration was observed predominantly in periportal areas in rats fed with the liquid diet ad libitum for 3 months. Compared to a large body of the literature concerning diet-induced obesity in experimental animals, information on animal models of fatty liver by dietary manipulations is insufficient. The results of this study clearly indicate that the overeating of a nutritionally adequate diet with reasonable fat content could result in remarkable fat accumulation in the liver in rats.     

A diet high in fat stimulates adipocyte proliferation in older (22 month) rats

The effect of a high fat diet in stimulating adipocyte proliferation, as measured by the incorporation of [3H]-thymidine into fat cell DNA, was studied in 22-month-old female Sprague-Dawley rats. Rats were fed a low fat (n = 10) or a high fat diet (n = 9) for a total of six days. On days 4 and 5 of dietary manipulation, rats were injected with 80 microCi/100 g body weight of [3H]-thymidine. Rats were continued on their respective diets for one more day, starved for 72 h and then refed a stock diet for three weeks in order to increase turnover of stroma cells, thus diluting the specific activity of stromal DNA with minimal effect on specific activity of fat cell DNA. The diet groups did not differ significantly with respect to body masses, food intake, parametrial (PARA) and retroperitoneal (RP) depot masses, cell number or cell size. The specific activity of DNA in both PARA and RP depots was greater in the adipocyte than in the stromavascular fraction. Specific activity of fat cells was significantly greater from rats fed the high fat than the low fat diet in both PARA and RP depots. Radioautography of adipose tissue confirmed that there was a greater percentage of adipocyte nuclei labeled in the rats fed the high fat diet. Also, there were few labeled nuclei found in stroma cells. In conclusion, older female rats increased adipocyte proliferation when fed a high fat diet.     

Anti-obesity effects of lipase inhibitor CT-II, an extract from edible herbs, Nomame Herba, on rats fed a high-fat diet

OBJECTIVE: To investigate the inhibitory effects of CT-II, extract of Nomame Herba, on lipase activity in vitro and on obesity in rats fed a high-fat diet in vivo. DESIGN: The assay for the inhibitory effect of CT-II on lipase activity was performed by measuring released free fatty acids after the incubation of the medium with CT-II, porcine pancreatic lipase and triolein (experiment 1). In vivo experiments, lean rats or obese rats (570-718 g) were fed a high-fat diet containing 60% fat with or without CT-II for 8 weeks (experiment 2), for 14 days (experiment 3) or for 12 weeks (experiment 4), respectively. MEASUREMENT: The time course of body weight, food intake, organ weight (parametrial fat, liver, heart and kidney) and plasma parameters (triglyceride, total cholesterol, glucose, AST, ALT and insulin), fecal output of total fat and total cholesterol were measured. Hepatic histological examinations were also performed. RESULTS: CT-II inhibited the porcine lipase activity dose-dependently in vitro (experiment 1). Body and liver weight were reduced and hepatic histological examination showed an amelioration of fatty liver in CT II treated animals (experiment 2). CT-II significantly inhibited body weight gain and plasma triglyceride elevation in a dose-dependent manner, without affecting food intake in lean rats fed the high-fat diet. Elevated plasma AST and ALT were also decreased (experiment 3). When obese rats fed the high-fat diet were treated with CT-II for up to 6 months, body weight was initially reduced and thereafter weight gain was significantly suppressed. Total body fat was also significantly reduced and significant reduction of plasma AST and ALT was observed (experiment 4). CONCLUSIONS: These results demonstrated that the lipase inhibitor CT-II is effective in preventing and ameliorating obesity, fatty liver and hypertriglyceridemia in rats fed a high-fat diet.     

Repetitive postprandial hypertriglyceridemia induces monocyte adhesion to aortic endothelial cells in Goto-Kakizaki rats

To compare the effects of postprandial hypertriglyceridemia and postprandial hyperglycemia on monocyte adhesion to endothelial cells, we investigated the effects of twice-daily standard diet (5% fat) and high-fat diet (30% fat) for 3 weeks on monocyte adhesion to endothelial cells and the expression of adhesion molecules in the aortic artery in non-obese type 2 diabetic Goto-Kakizaki rats. Fasting glucose, insulin, non-esterified fatty acid (NEFA), HbA1c, and body weight were comparable between the two diet groups. Postprandial glucose and insulin were higher in the standard diet group, while postprandial NEFA and triglyceride were higher in the high fat diet group, compared with the other group. The number of monocyte adherent to endothelial cells was higher in the high-fat diet group than the standard diet group. Consumption of high-fat diet resulted in overexpression of heme oxygenase-1, intercellular adhesion molecule-1 (ICAM-1), and connecting segment-1 fibronectin on the arterial wall, compared with standard diet. Thus, our data demonstrated that short-term intermittent high-fat diet prevented postprandial hyperglycemia in a model of type 2 diabetes without a significant increase in body weight. However, the resulting postprandial hypertriglyceridemia induces more monocyte adhesion to endothelial cells than postprandial hyperglycemia. This increased monocyte adhesion is associated with the increased aortic expression of adhesion molecules such as ICAM-1, and connecting segment-1 fibronectin.     

高脂乳剂灌胃构建大鼠非酒精性脂肪性肝病模型可靠性的再研究

目的研究高脂乳剂灌胃构建大鼠非酒精性脂肪性肝病(NAFLD)模型的可靠性。方法成年Wistar雄性大鼠47只,体重(170±15)g,随机分为正常组、模型组。所有大鼠给予基础饲料,同时应用高脂乳剂灌胃法喂养模型组大鼠,而对照组大鼠用生理盐水灌胃替代。在4周、8周、12周三个时间段,光镜观察肝组织病理形态学改变;分别检测各组体重和肝脏湿重,计算肝指数(LI);检测大鼠空腹血清ALT和AST水平,观察是否存在组间差异;结果与对照组对比,模型组12周LI显著增大(P=0.000);12周时,血清ALT(P=0.030)及AST(P=0.000)较同期对照组升高;病理结果显示模型组4周肝小叶腺泡3区肝细胞少量脂肪空泡形成;模型组8周肝小叶腺泡3区肝细胞弥漫性脂肪空泡形成,少量炎性细胞浸润;模型组12周肝小叶腺泡3区弥漫性脂肪空泡形成,大量炎性细胞浸润,符合NAFLD典型的病理特征。本实验大鼠死亡率2%,模型构建成功率98%。结论脂肪乳剂灌胃12周可以成功复制大鼠NAFLD模型,该模型具有较强的临床相似性、可靠性。     

Effect of nutritional counselling on hepatic, muscle and adipose tissue fat content and distribution in non-alcoholic fatty liver disease

INTRODUCTIONThe incidence of non-alcoholic fatty liver disease (NAFLD) has increased rapidly over the last few years and is now one of the commonest causes of abnormal liver function test (LFT) results in patients presenting to hepatology clinics in both …     

Type and amount of dietary fat affect relative concentration of cholesterol in blood and other tissues of rats

The effects of diet on tissue cholesterol disposition in the rat were studied. Growing rats were fed a nonfat dry milk supplemented with two levels of soy-bean oil (SBO) and tallow (T) such that either 30% or 50% of total dietary calories came from fat. Two of four groups of rats fed the diets with 50% of calories from fat were supplemented with 20% ground whole oats. Considering all diets, rats fed SBO had higher blood and kidney cholesterol than did rats fed T; supplementation of the diet with oats increased the plasma cholesterol of the "50%" SBO rats and , conversely, decreased plasma cholesterol of the "50%" T rats. Muscle cholesterol content was not affected by variations in dietary fat and oats. In all treatments, cholesterol concentration of epididymal fat and liver were greater in the SBO-fed than in the T-fed rats.     

Effect of high fat diet on body weight and mammary tumor latency in MMTV-TGF-alpha mice

OBJECTIVE: The role of high fat diets in breast cancer/mammary tumor (MT) development is controversial. This may be partially attributable to variable effects of high fat diets on body weight. Here, we used a moderately high fat diet (32.5% fat calories) expected to cause obesity in most mice, but predicted to result in some mice remaining in the weight range of mice fed the low fat diet (11% fat calories). This provided the opportunity to compare mice fed the high fat diet exhibiting different body weights and mice of similar weight consuming high vs low fat diets. EXPERIMENTAL METHODS: Transgenic MMTV-TGF-alpha mice, a model of postmenopausal breast cancer, consumed a low fat diet, that is, chow-fed (n=25) or a moderately high fat diet from 10 weeks of age (n=51). Body weight at 34 weeks of age was used to assign high fat diet mice to obesity-prone>overweight>obesity-resistant groups (n=17) (P<0.0001). Mice were euthanized when MTs developed or at 85 weeks of age. RESULTS: Final body weights were highest in obesity-prone>overweight >obesity-resistant=chow-fed mice. Fat pads and fat pad:carcass were heaviest in obesity-prone followed by overweight mice. However, obesity-resistant mice had fat pad weights and fat pad:carcass three-fold greater than chow-fed mice. All groups had MT incidences between 72 and 82%. Obesity-prone mice exhibited the shortest MT latency (P<0.0001), but obesity-resistant mice had significantly shorter latency than chow-fed mice. CONCLUSIONS: Consumption of a high fat diet increased adiposity and shortened MT latency in relation to its effect on body weight. These results indicate a complex role of dietary fat level on mammary tumorigenesis.     

Interaction between corticosterone and insulin in obesity: regulation of lard intake and fat stores

Passive elevations in glucocorticoids result in increased insulin and abdominal obesity with peripheral wasting, as observed in Cushing's syndrome, with little effect on chow intake. In the absence of insulin (streptozotocin-induced diabetes) diabetic rats markedly increase their chow intake in proportion to glucocorticoids. Given a choice of lard or chow, diabetic rats first eat lard, then reduce caloric intake to normal for 48 h before returning to hyperphagia on chow alone. We performed three experiments to determine the relationship of corticosterone and insulin to lard intake, chow intake, body weight, hormones, and fat depots. The results of these studies clarify the actions of both circulating glucocorticoids and insulin on caloric intake in adult male rats. Our experiments show that glucocorticoids provoke dose-related increases in total caloric intake that persist for days and weeks; the results also suggest that increasing insulin concentrations stimulated by glucocorticoids determine the amount of fat intake. Furthermore, we show that lard intake is associated with increasing insulin concentrations. Additionally, the results in adrenalectomized and adrenalectomized, streptozotocin-induced diabetic rats strongly suggest that it is a combination of corticosterone and insulin that increases abdominal fat depot weight. Independently of the hormonally manipulated rats, the results also show that intact rats voluntarily eat a considerable and stable proportion of their daily calories as lard when given a choice between lard and chow. These results suggest that some human obesities may result from elevated glucocorticoids and insulin increasing the proportional intake of high density calories.     

Chronic treatment with either dexfenfluramine or sibutramine in diet-switched diet-induced obese mice

Dexfenfluramine (DEX) and sibutramine (SIB) are effective antiobesity agents. Their effects on weight control and hormone profile have not been previously studied in diet-switched diet-induced obese (DIO) mice, in which treatment is initiated upon cessation of a low-fat diet and resumption of a high-fat diet. Furthermore, their effects on circulating ghrelin in obese humans or in animal models of obesity have not yet been reported. Male C57BI/6J DIO mice after 16 wk on a high-fat diet (HF, 60 kcal% fat) were switched to a low-fat diet (LF, 10 kcal% fat) for 50 d. HF diet resumed concurrently with treatment for 28 d with DEX 3 and 10 mg/kg, twice a day (BID); SIB 5 mg/kg BID; or vehicle. Rapid weight regain ensued in vehicle-treated DIO mice. DEX or SIB treatment significantly blunted the body weight gain. Caloric intake was decreased acutely by DEX or SIB vs vehicle during the first 2 d treatment, but returned to control after 5 d. At the end of study, epididymal fat weight and whole body fat mass determined by DEXA scan were decreased by DEX 10 mg/kg, and whole body lean mass decreased with DEX 3 mg/kg treatment. Circulating ghrelin on d 28 was increased with either DEX 3 or 10 mg/kg treatment, while growth hormone and insulin were decreased. Leptin was also decreased in the DEX 10 mg/kg group. SIB did not significantly affect fat mass, ghrelin, growth hormone, insulin, or leptin. Mice chronically fed LF diet maintained a lower caloric intake, gained less weight and fat mass than diet-switched mice, and had higher ghrelin and lower insulin and leptin. In summary, weight regain in diet-switched DIO mice is delayed with either DEX or SIB treatment. DEX treatment of diet-switched DIO mice decreased growth hormone, insulin, leptin, fat mass, lean mass, and increased ghrelin, while SIB only decreased body weight.     

Prolonged endothelial-dependent and -independent arterial dysfunction induced in the rat by short-term feeding with a high-fat,high-sucrose diet

Obesity induced by long-term consumption of a fat-rich diet causes marked endothelial dysfunction. In this study we aimed to determine whether endothelial impairment is due to obesity or the diet per se. Wistar rats were fed either standard laboratory chow throughout (controls), or given a highly palatable diet (diet-fed) for 3 days, or fed the diet for 3 days and then returned to chow for 3 further days before sacrifice (diet-to-chow). Body weight, fat and gastrocnemius muscle mass, and plasma levels of glucose, insulin and leptin were all comparable between the three groups. Diet-fed rats had significantly raised plasma non-esterified fatty acids (NEFA; P=0.0005) and triglyceride levels (P=0.00001). The diet-to-chow group had intermediate plasma NEFA and triglyceride levels (significantly higher than in controls, P=0.019 and P=0.0035 for NEFA and triglycerides, respectively). There were no changes in noradrenaline and KCl responses in mesenteric arteries, whereas vasorelaxation to both carbamylcholine and sodium nitroprusside were significantly attenuated in the diet-fed group (by up to 18%; P=0.00001). Both these responses remained largely impaired in the diet-to-chow group. By contrast, histamine-induced vasorelaxation was comparable between all three groups. Thus, short-term feeding with a palatable diet induces marked endothelium-dependent and -independent arterial dysfunction. These effects occurred in the absence of obesity and largely persisted after removal of the palatable diet. Diet per se can have important detrimental effects on arterial function, which may be mediated by raised NEFA and/or triglyceride levels.     

高脂血症性脂肪性肝病大鼠肝脏Intermedin的表达

目的研究高脂血症性脂肪性肝病大鼠血浆及肝组织intermedin（IMD）的变化，探讨新的小分子活性肽IMD在高脂血症性脂肪肝大鼠病理过程中的意义。方法雄性SD大鼠16只，随机均分为正常组与高脂组。高脂饲料喂养8周后，观察大鼠肝脏病理学变化，检测大鼠血脂及肝功能；放免法测定血浆及肝组织匀浆IMD含量。结果①高脂组大鼠体重、肝脏湿重和肝指数均显著高于正常组（P均〈0．01）。②高脂组TC、TG、LDL-C、ALT及AKP均显著高于正常组（P均〈0．01），HDL-C则低于正常组（P〈0．05）。③高脂组肝组织匀浆IMD水平较正常组高51．3％（P〈0．01），血浆IMD水平两组间差异无统计学意义（P〉0．05）。结论IMD可能在脂质代谢紊乱对肝损害的过程中扮演了重要的角色。     

The consequences of early overnutrition for fat cell size and number: the pig as an experimental model for human obesity

(1) The objectives of these studies were: (a) to determine the period during which fat cells were being formed in different fat depots in the pig; (b) to discover whether total fat cell number could be affected by overfeeding from weaning or later in life, and (c) to examine the domestic pig as a model for human obesity studies especially as to the influence of the energy intake at different stages in life on fat cell size and number. (2) Pigs were weaned at six weeks of age and allocated to one of four diets. Group H was fed to appetite on a high carbohydrate diet and became extremely obese. Group L was fed at half the energy intake of group H; these animals grew steadily but deposited little adipose tissue. Group L-H was fed as group L for 40 weeks and then as group H for the rest of the experiment, while group H-L was fed as group H for 40 weeks and then placed on a very restricted ("slimming") diet for the remainder of the experiment. (3) The volume of fat cells in group H was about four-fold greater than in group L at the end of the experiment. Cell volume increased rapidly when group L was fattened after 40 weeks and could be reduced significantly, albeit slowly, when group H was "slimmed". (4) There was a significant increase in the apparent number of fat cells in the depots of overfed pigs that did not diminish when the animals were "slimmed". However, in restricted pigs subsequently fattened, there was an apparent steady increase in fat cell number that eventually reached the same figure as in pigs overfed from weaning. (5) The standard methodology is inadequate to make broad generalizations about the influence of diet on cellularity. First, the development of fat cell size and number follows different time scales in different depots. It is essential to monitor several sites before attempting to estimate cell number. Secondly, since cells with diameters less than about 15 micrometer are not detected, "empty" cells, containing no fat, may be present from birth: subsequently they may be filled when energy intake is appropriate so that later they become visible, and are recorded as fat cells. In these cases there will be an "apparent" but not a real increase in cell number.     

丹栀逍遥散对非酒精性脂肪性肝病大鼠LKB1/AMPK/ACC通路及肝脂肪变性的影响

目的:探讨丹栀逍遥散对非酒精性脂肪性肝病(NAFLD)大鼠肝脏激酶B1(LKB1)/腺苷酸活化蛋白激酶(AMPK)/乙酰辅酶A羧化酶(ACC)通路及肝脂肪变性的影响。方法:SD雄性大鼠随机分为空白组、模型组、水飞蓟宾组(26.25 mg·kg^-1)、丹栀逍遥散高、中、低剂量组(38.0、19.0、9.5 g·kg^-1),每组13只。采用高脂饲料连续喂养8周复制非酒精性脂肪肝(NAFLD)大鼠模型。模型复制成功后水飞蓟宾组和丹栀逍遥散各剂量组大鼠开始灌胃给予相应的药物,连续给药4周,给药结束后进行取材和相关指标的检测。给药期间,观察各组大鼠的精神状况、毛色、饮食、活动等一般状态,记录给药前后大鼠体重变化;取大鼠肝、肾、脾脏并称重,计算脏器指数;生化法检测肝组织中丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、甘油三脂(TG)、总胆固醇(TC)、游离脂肪酸(NEFA)含量;苏木精-伊红染色(HE)观察各组大鼠肝组织病理变化;Western blot检测肝组织中LKB1、AMPKα1、AMPKα2、ACC及其磷酸化水平。结果:与空白组相比,模型组大鼠毛色发黄暗淡,精神萎靡;体重增量、肝脏指数、肝组织中ALT、AST、TG、TC、NEFA水平均显著升高(P<0.05),肝细胞排列紊乱,胞界不清晰,较多的脂肪空泡;肝细胞中LKB1、p-LKB1、AMPKα1、p-AMPKα1、AMPKα2、p-AMPKα2、p-ACC蛋白表达水平明显降低,ACC蛋白表达升高(P<0.05);与模型组相比,水飞蓟宾组和丹栀逍遥散高、中剂量组大鼠一般状态有不同程度的改善,体重增量、肝脏指数、肝组织中ALT、AST、TG、TC、NEFA水平均显著降低(P<0.05),病理损伤程度减轻;肝细胞中LKB1、p-LKB1、AMPKα1、p-AMPKα1、AMPKα2、p-AMPKα2、p-ACC蛋白表达水平明显升高,ACC蛋白表达降低(P<0.05)。结论:丹栀逍遥散可能通过LKB1/AMPK/ACC信号通路,降低脂肪的合成,改善肝功能,减轻NAFLD模型大鼠肝脂肪变性。     

Effects of low-calorie diet on steatohepatitis in rats with obesity and hyperlipidemia

AIM: To evaluate the effects of low calorie diet (LCD) on nonalcoholic steatohepatitis (NASH) in rats with obesity and hyperlipidemia.METHODS: 29 Sprague-Dawley (SD) rats were randomly divided into three groups. The animals in control (n=9) and NASH group (n=10) were fed on standard rat diet and high fat diet respectively for 12 weeks, ten rats in LCD group were fed on high fat diet for 10 weeks and then low calorie diet for 2 weeks. At the end of the experiment, body weight, abdominal adipose content, liver function, and hepatopathological changes were examined to evaluate the effect of different feeding protocols on the experimental animals.RESULTS: There was no death of animal in the experimental period. All rats in the NASH group developed steatohepatitis according to liver histological findings. Compared with the control group, body weight (423.5±65.2 vs 351.1±43.0 g,P＜0.05), abdominal adipose content (14.25±1.86 vs9.54±1.43,P＜0.05), liver index (3.784-±0.533 vs2.957±±0.301%, P＜0.01),total serum cholesterol (1.60±0.41 vs 1.27±0.17 mmol/L, P＜0.05)and free fatty acids (728.2±178.5 vs 429.2±96.7 mmol/L,P＜0.01), serum alanine aminotransferase (1 257.51±671.34vs671.34±118.57 nkat/L, P＜0.05) and aspartic aminotransferse (2 760.51±998.66 vs 1 648.29±414.16 nkat/L, P＜0.01) were significantly increased in the NASH group. Whereas, when rats were fed on LCD protocol, their body weight (329.5±38.4 g,P＜0.01), abdominal adipose content (310.21±1.52 g, P＜0.05),liver index (3.199±0.552 %, P＜0.05), and serum alanine aminotransferase (683.03±245.49 nkat/L, P＜0.05) were significantly decreased, and the degree of hepatic steatosis (P＜0.05) was markedly improved compared with those in the NASH group. However, no significant difference was found in serum lipid variables and hepatic inflammatory changes between the two groups.CONCLUSION: LCD might play a role in the prevention and treatment of obesity and hepatic steatosis in SD rats,but it exerts no significant effects on both serum lipid disorders and hepatic inflammatory changes.     

高脂高糖饮食对自发性高血压大鼠内皮素表达及肾功能的影响

目的探讨高脂高糖饮食对自发性高血压大鼠(SHR)内皮素1表达和肾功能的影响。方法 24只6周龄雄性SHR随机分为高脂高糖组和普通饲料组,每组12只。观察高脂高糖饮食对体质量、血糖、血脂、胰岛素、内皮素1和肾功能等的影响,计算胰岛素抵抗指数(HOMA-IR)、肌酐清除率(Ccr)、尿白蛋白/肌酐比值(ACR)的变化。提取肾脏总RNA,实时定量RT-PCR检测内皮素1mRNA,HE染色观察肾脏的病理变化。结果与普通饲料组比较,高脂高糖组大鼠干预后第12周体质量增加24%,TC、TG水平、胰岛素及HOMA-IR升高,内皮素1增高[(45.0±0.2)ng/L vs(25.0±0.1)ng/L];Ccr降低[(0.3±0.2)ml/min vs(0.6±0.1)ml/min],差异有统计学意义(P<0.05,P<0.01)。ACR升高(P<0.05);肾脏内皮素1mRNA增高(197.9±22.2)vs(100.3±11.4),差异有统计学意义(P<0.05)。结论长期高脂高糖饮食可加重SHR肾损害,其机制可能与胰岛素升高、HOMA-IR增加及肾脏内皮素1mRNA表达上调相关。