Ethanol intake during lactation impairs milk production in rats and affects growth and metabolism of suckling pups.

From parturition, lactating Wistar rats were given 20% alcohol in drinking water and fed a solid diet ad lib (group AL). Pair-fed (PF) and control (C) rats were fed solid diet and given water ad lib (C). All animals were sacrificed on the 12th day of lactation. Ethanol treatment decreased food intake and milk production in lactating rats to a greater level than in PF rats, and a greater reduction in body weight of the AL pups was noted. Brain weight, protein concentration, and DNA content were also lower in pups of AL dams than of PF dams, whereas liver glycogen concentration was higher in the former. Pups from AL dams had higher circulating levels of beta-OH-butyrate, triglyceride, and free fatty acids than those from either C or PF dams. Plasma glucose concentration was lower in both PF and AL than in C pups, whereas the AL group had lower plasma protein concentration than any of the other groups. We conclude that maternal alcohol intake during lactation greatly impairs milk production, and although the known increase of lipid content in milk in rats studied under similar conditions allows an enhanced lipidic components in the pups, this adaptation does not allow normal growth and brain development.     

Purified chickpea or lentil proteins impair VLDL metabolism and lipoprotein lipase activity in epididymal fat,but not in muscle,compared to casein,in growing rats

Background  It is well known that the legume proteins have a lowering effect on plasma cholesterol and triacylglycerols (TG) concentrations compared to animal proteins. The protein itself, as well as non-protein constituents, naturally present in legumes may be implicated. Aim of the study  The effects of various dietary purified legumes proteins compared to casein, were determined on plasma TG level, VLDL concentration and composition. Moreover, lipoprotein lipase (LPL) activity in epididymal fat, gastrocnemius and heart was investigated to evaluate in these tissues their capacity to release free fatty acids from their TG substrate and the liver capacity to stock the TG. Methods  Weaning male Wistar rats were fed ad libitum one of the following diets: 200 g/kg diet of purified proteins of lentil (L), or chickpea (CP) or casein (CAS). At day 28, VLDL were isolated from plasma sample by a single ultracentrifugation flotation. Hepatic lipase and LPL activity in epididymal fat, gastrocnemius and heart were measured by using glycerol tri [9–10(n)-³H] oleate emulsion as substrate. Results  Compared with CAS diet, the CP and L protein diets exhibited similar cholesterolemia, but lower triglyceridemia (1.9-fold and 2.5-fold) and VLDL particle number, as measured by their reduced contents of TG and apolipoproteins. CP and L protein diets reduced liver TG and cholesterol by 31 and 45%, respectively compared to CAS diet. Furthermore, LPL activity in adipose tissue of rats fed CP or L was 1.6-fold lower than that of rats fed CAS. There was no significant difference in heart and gastrocnemius LPL activities with the three proteins. In contrast, hepatic lipase activity was higher in rats fed CP and L diets. Conclusion  The low food efficiency ratio of purified CP and L proteins related to CAS is associated with decreased plasma VLDL and adipose tissue LPL activity. The low liver TG concomitant with reduced TG and apolipoproteins contents of VLDL confirm that hypotriglyceridemia is essentially due to impaired synthesis, exportation and transport of TG by VLDL which prevent lipid storage in adipose tissue.     

Ethanol intake during lactation. I. Effects On dams' metabolism and pups' body weight gain.

Wistar lactating rats (8 pups per dam) had free access to either tap water (control group, C) or one of three concentrations of ethanol (E) in the drinking water: 5% (E5), 10% (E10), and 20% (E20). All animals received normal rat chow ad libitum and were killed on day 12 of lactation. Intake of both 10% and 20% ethanol solutions decreased food intake, dams' body weight, and pups' body weight gain as compared with findings in the C group. The relative weights (g/100g b.w.) of the mammary glands (MG) and of the parametrial white adipose tissue depot were decreased only in E20 as compared with findings in the C group. Protein and lipid content of these tissues were not altered in any of the ethanol groups. In comparison with the C group, the lipogenesis rate was increased in the MG (135. 6%) and liver (120.2%) in E5 and the MG (58.1%) and parametrial white adipose tissue depot (147.0%) in E20. No modifications in lipogenesis rate were noted in E10. The malic enzyme activity was decreased in the MG in E10 (25.3%) and E20 (26.4%) and in the liver in E20 (45.7%). In E5, however, it was increased in the liver (23. 9%). The activity of ATP-citrate lyase in the liver was decreased in E20 (56.7%), while it was increased by 37.5% in E5 and 34.2% in E10. Blood glucose concentration of dams was not affected by ethanol ingestion. However, plasma triacylglycerol concentration was higher in E10 (17.9%) and E20 (13.3%) than in the C group, and plasma protein was lower in E20 (15.7%) than in C. We concluded that alcohol intake during lactation increased the MG lipogenesis rate; although at the highest dose, this metabolic alteration was not enough to allow normal pups' growth. However, the low dose of ethanol (5%), despite having altered dams' metabolism, did not affect pups' body weight gain.     

Lipoprotein lipase activity in skeletal muscle and brown adipose tissue of pregnant and lactating rats

Changes in lipoprotein lipase (LPL) activity during pregnancy and lactation were followed in skeletal muscles and interscapular brown adipose tissue (BAT) of rats fed two diets differing in energy density (high carbohydrate or high fat). Rats were decapitated after 7, 19 or 21 d of pregnancy or after 3 or 12 d of lactation. Virgin rats and females separated from their litter just after delivery were used as nonpregnant and nonlactating controls, respectively. Blood was collected for determination of plasma glucose, triglycerides (TG) and nonesterified fatty acids (NEFA). Soleus, extensor digitorum longus (EDL), diaphragm and interscapular BAT were rapidly removed and frozen in liquid nitrogen for LPL activity measurement. LPL activity was not significantly higher in muscles and BAT of virgin rats fed the high fat diet than in those of rats fed the high carbohydrate diet. No significant change of skeletal muscle LPL activity was observed during pregnancy, regardless of the diet fed. Although BAT exhibited a transitory hypertrophy during pregnancy, its LPL activity was not significantly altered; during lactation BAT lost weight and its LPL activity dropped sharply when either diet was fed, leaving more TG available for milk production.     

锌对免疫器官的影响

通过建立大鼠缺锌（ＺＤ）、高锌（ＺＥ）模型，研究锌对免疫器官——骨髓、胸腺、脾脏的影响。结果表明：（１）ＺＤ、ＺＥ组体重、体重增长值、饲料效价均非常显著地低于配对（ＰＦ）组和自由喂养（ＡＬ）组，缺锌补锌（ＺＤ＋ＡＬ）组达正常水平。（２）ＺＤ组血清、毛发、股骨、肝脏锌均非常显著地低于ＰＦ、ＡＬ组，而ＺＥ组则相反，ＺＤ＋ＡＬ组达正常水平。（３）ＺＤ、ＺＥ组的胸腺重量、胸腺指数、胸腺肽量和胸腺活性均非常显著地低于ＰＦ、ＡＬ组，ＺＤ＋ＡＬ组达正常水平。（４）ＺＤ、ＺＥ组脾脏重量、脾脏指数均非常显著地低于ＰＦ、ＡＬ组，ＺＤ＋ＡＬ组达正常水平。（５）ＺＤ、ＺＥ组骨髓细胞３Ｈ一ＴｄＲ掺入率和外周血白细胞总数显著下降，其中尤以淋巴细胞减少为着。（６）骨髓细胞、脾脏淋巴细胞周期显示ＺＤ、ＺＥ组静止期细胞明显增高，而增殖期细胞下降，与ＰＦ、ＡＬ组间差别非常显著。以上结果提示，适量锌有促进免疫器官——骨髓、胸腺、脾脏发育和功能活动的作用。而缺锌和高锌则抑制免疫器官的发育和免疫细胞的功能。     

Lipoprotein lipase activity and chylomicron clearance in rats fed a high fat diet

The relationships of tissue and plasma lipoprotein lipase (LPL) activities to tissue uptake and plasma clearance of 14C-labeled chylomicron-triglyceride (14C-CM-TG) were studied in female rats fed isoenergetic and isonitrogenous control (12% kJ from fat) or high fat diets (72% kJ from fat) for 8 wk. Animals fed the high-fat diet had higher levels of fasting plasma triglycerides and lower LPL activities in heart, renal adipose tissue and post-heparin plasma. Changes in LPL activities of skeletal muscles varied among muscles with higher values in the soleus and plantaris (32-61%) and no differences in the gastrocnemius. The lower LPL activity in renal adipose tissue was associated with lower uptake of fatty acids from 14C-CM-TG by adipose. Fatty-acid uptake from labeled TG was not associated with tissue LPL activity in other tissues. Clearance of 14C-CM-TG from plasma and the half-lives of 14C-CM-TG were similar in both dietary groups. These data indicate that tissue and plasma LPL activities are not a direct index of uptake of fatty acids by tissues or clearance of chylomicron triglycerides.     

Vitamin A intake affects the contribution of chylomicrons vs. retinol-binding protein to milk vitamin A in lactating rats

To investigate the influence of vitamin A intake on the contribution of chylomicrons vs. holo retinol-binding protein to milk vitamin A, female rats were fed diets containing either 10 (n = 6) or 50 micromol vitamin A/kg body (n = 4) during pregnancy and through d 13 of lactation. [3H]Vitamin A was incorporated into each diet beginning on d 6 of lactation. Vitamin A concentrations on d 13 were significantly higher in dam liver (x 3), pup liver (x 2.6), milk (x 2.5) and mammary tissue (x 1.3) in rats consuming the higher level of vitamin A. In both groups, vitamin A specific activities in plasma and milk reached apparent plateaus by 2.33 d after addition of [3H]vitamin A to the diets. Vitamin A specific activity in milk was higher than in plasma at all times in both groups. The estimated minimum contribution of chylomicrons to milk vitamin A was 32 +/- 3% in rats fed the lower level of vitamin A vs. 52 +/- 10% at the higher level (P = 0.014). We concluded that dietary vitamin A, like triglycerides, may be directed to mammary tissue during lactation for preferential secretion into milk; thus, increasing vitamin A intakes will increase the contribution of dietary vitamin A to milk. In contrast to milk, mammary tissue vitamin A turns over very slowly.     

普洱茶茶褐素对大鼠激素敏感性脂肪酶活性及其mRNA表达的影响

目的研究普洱茶茶褐素对大鼠肝脏和附睾脂肪组织中HSL活性及其mRNA表达的影响。方法 90只SD大鼠随机分成正常对照组(Ⅰ组)、高脂饲料组(Ⅱ组)和高脂饲料+茶褐素组(Ⅲ组),每组选取10只于实验D15、D30和D45处死,分别测定其血清TG、TC、LDL-C和HDL-C值以及肝脏和附睾脂肪组织中HSL活性及其mRNA表达水平。结果 (1)试验D30、D45时,Ⅱ组大鼠TG、TC、LDL-C水平均较Ⅰ组显著升高(P0.05,P0.01),HDL-C水平较Ⅰ组显著降低(P0.05,P0.01),而Ⅲ组大鼠TG、TC、LDL-C水平则较Ⅱ组显著降低(P0.05,P0.01),HDL-C水平较Ⅱ组显著升高(P0.05,P0.01)。(2)D30时,Ⅲ组附睾脂肪组织HSL活性高于Ⅰ组(P0.05);D45时,Ⅲ组肝脏组织HSL活性高于Ⅰ组(P0.05),Ⅱ组和Ⅲ组中附睾脂肪组织HSL活性显著高于Ⅰ组(P0.01)。(3)D30时,Ⅱ组和Ⅲ组中附睾脂肪组织HSLmRNA表达则分别高于Ⅰ组(P0.05,P0.01),且Ⅱ组和Ⅲ组之间差异极显著(P0.01);D45时,Ⅲ组大鼠肝脏组织HSL mRNA表达明显高于Ⅰ组(P0.05),Ⅱ组和Ⅲ组中附睾脂肪组织HSLmRNA表达则均高于Ⅰ组(P0.05,P0.01),且Ⅱ组和Ⅲ组之间差异极显著(P0.01)。结论普洱茶茶褐素对大鼠降血脂效果明显,并可显著增强大鼠肝脏和附睾脂肪组织HSL活性及其mRNA的表达,是茶褐素降血脂功效的重要作用机制之一。     

Effect of peroral xylitol on the concentration levels of lipids and electrolytes in rat tissues

The effect of glucose (G) and xylitol (X) feeding on the fat and electrolyte metabolism was studied with 24 adult male rats divided into three groups of 8 for a 30-day experiment. One group was fed the stock diet supplemented with X (3000 mg/kg body wt./day); the second group the same diet supplemented with G (3000 mg/kg body wt./day), and the third the stock diet without added carbohydrates. During the last 24-hr period of the feeding schedule the animals were given ¹⁴C(U)-labeled G or X. Samples of serum, liver, kidneys, pancreas, spleen, duodenum wall, parotid glands, and the entire submandibular and lacrimal glands were analyzed for neutral lipids, phospholipids, Na, K, Mg, Ca, Fe, Cl^? and inorganic phosphorus. The X-fed animals showed smaller weight gains and their lacrimal and submandibular glands were significantly smaller than in other feeding groups. The weights of kidneys, however, did not differ significantly. At least in the case of submandibular glands, the reduced gland weights were associated with decreased levels of tissue K, Ca, Mg, inorganic phosphorus and Cl^?. Several organs of the G-fed animals displayed reduced Na contents. X-fed rats showed elevated concentrations of Fe in livers, kidneys and spleen, increased labeling of serum neutral lipids, and increased concentrations of triglycerides (TG) and free fatty acids (FFA) in lacrimal and submandibular glands. The G-fed animals showed decreased concentrations of serum lysolecithin, but elevated levels of TG in serum and the lacrimal and submandibular glands. X feeding increased serum lysolecithin compared to G feeding. These results suggest that physiological, peroral X administration increases the rate of lipolysis, facilitates the absorption of iron and exerts specific effects on exocrine gland function in rats. Most findings in the X group were significant only when compared to the G group. Minor differences existed when X-fed rats were compared to control rats. Since high carbohydrate diets usually result in reduced plasma FFA and increased plasma TG, the higher FFA and lower TG in the X-fed rats compared to the G-fed group, therefore, represented a lack of high G effects.     

Energy restriction reduces long-chain saturated fatty acids associated with plasma lipids in aging male rats

Energy restriction is associated with decreased plasma insulin and glucose concentrations, whereas long-chain saturated fatty acids (LCSFA) are strongly associated with insulin resistance. Our hypothesis is that energy restriction reduces LCSFA associated with plasma lipids in adult aging rats. Plasma LCSFA associated with triglycerides (TG), nonesterified fatty acids and phospholipids, as well as glucose, insulin, free fatty acids, TG and adipocyte glucose transport and insulin-sensitive glucose transporter (GLUT4) content were determined in aging, energy restricted [ER; 60% of ad libitum (AL) intake] and AL rats. In ER rats, plasma glucose concentrations were lower than in AL rats at each age. In contrast, body weight and plasma TG concentrations increased with age in both groups, but especially in the AL rats. In AL rats, combined LCSFA associated with plasma lipids was greater than in ER rats (P < 0.0001). Adipocyte insulin-stimulated glucose transport decreased in both groups with age but was most severe in AL rats, whereas GLUT4 was reduced only in AL rats. In ER rats it is possible that decreased plasma LCSFA contribute to reduced blood glucose concentrations as well as increased adipocyte GLUT4 compared with AL rats.     

Bile duct obstruction is associated with early postoperative upregulation of liver uncoupling protein-2 and reduced circulating glucose concentration in the rat

ObjectiveTo evaluate whether upregulation of liver and muscle uncoupling protein 2 (UCP-2) is an acute phenomenon in obstructive jaundice and associated with secondary metabolic effects.MethodsMale Sprague-Dawley rats were divided into four groups: bile duct ligated (BDL) and sham-operated pair-fed (PF), ad libitum fed (AL), and controls. BDL, PF, and AL rats were further divided into subgroups according to the interval postoperatively when they were reanesthetized and sampled for tissue and blood: 2, 4, and 8 d, respectively. Bilirubin, liver enzymes, glucose, free fatty acids, and insulin in blood plasma were analyzed. Liver and muscle tissue were sampled for UCP-2 and adenosine triphosphate analysis.ResultsThe BDL rats showed an increase of the liver UCP-2 expression compared with PF and AL rats (P < 0.05) 4 d postoperatively. Liver adenosine triphosphate in BDL rats showed a decrease compared with sham-operated controls at all intervals (P < 0.05). Plasma glucose concentration in BDL rats was decreased compared with the other groups. Free fatty acids showed an initial increase 2 d postoperatively compared with sham-operated controls and PF and AL rats (P < 0.05) at the corresponding time point.ConclusionObstructive jaundice is associated with an early upregulation of liver UCP-2, reduced liver adenosine triphosphate content, and decreased plasma glucose concentration, supporting the hypothesis that obstructive jaundice results in impaired energy homeostasis in the liver, which might cause decreased glucose output and hypoglycemia as a consequence.     

Medium-chain oil reduces fat mass and down-regulates expression of adipogenic genes in rats

OBJECTIVE: To test the hypothesis that adipose tissue could be one of the primary targets through which medium-chain fatty acids (MCFAs) exert their metabolic influence. RESEARCH METHODS AND PROCEDURES: Sprague-Dawley rats were fed a control high-fat diet compared with an isocaloric diet rich in medium-chain triglycerides (MCTs). We determined the effects of MCTs on body fat mass, plasma leptin and lipid levels, acyl chain composition of adipose triglycerides and phospholipids, adipose tissue lipoprotein lipase activity, and the expression of key adipogenic genes. Tissue triglyceride content was measured in heart and gastrocnemius muscle, and whole body insulin sensitivity and glucose tolerance were also measured. The effects of MCFAs on lipoprotein lipase activity and adipogenic gene expression were also assessed in vitro using cultured adipose tissue explants or 3T3-L1 adipocytes. RESULTS: MCT-fed animals had smaller fat pads, and they contained a considerable amount of MCFAs in both triglycerides and phospholipids. A number of key adipogenic genes were down-regulated, including peroxisome proliferator activated receptor gamma and CCAAT/enhancer binding protein alpha and their downstream metabolic target genes. We also found reduced adipose tissue lipoprotein lipase activity and improved insulin sensitivity and glucose tolerance in MCT-fed animals. Analogous effects of MCFAs on adipogenic genes were found in cultured rat adipose tissue explants and 3T3-L1 adipocytes. DISCUSSION: These results suggest that direct inhibitory effects of MCFAs on adiposity may play an important role in the regulation of body fat development.     

Adequate evaluation of HSL mass and activity in rat adipose tissue in fasting and aging-related obesity

Adipose tissue is a unique tissue because its mass is readily changed by altering nutritional conditions. Therefore the activity and content of enzyme in the adipose tissue is significantly differed according to the way of their presentation: per g tissue, per whole tissue, or per cell number. In the present study, the effects of the ways of expressing the hormone sensitive lipase (HSL) activity and content were studied in rat by decreasing or increasing adipose tissue. Fasting caused a progressive decline in body weight and in the weight of the epididymal fat pad. When the HSL content was expressed per g of adipose tissue, the lipase activity and immunoreactive HSL protein content in fasting rats were higher than those in fed rats. On the other hand, when they were expressed as per fat pad, the lipase activity and immunoreactive HSL protein in fasting rats were lower than those in fed rats. The opposite results were observed in obesity. When the HSL content was expressed per g of adipose tissue, the lipase activity and immunoreactive HSL protein in obese rats were lower than in control rats. However, when the HSL content was expressed per fat pad, the lipase activity and immunoreactive HSL protein in the obese rats were higher than in the control rats. Therefore we must pay careful attention to the way of presentation of adipose tissue enzyme contents.     

Nitric oxide synthase inhibitor attenuates intestinal damage induced by zinc deficiency in rats

A nitric oxide synthase (NOS) inhibitor, NG-nitro-L -arginine methyl ester (L-NAME), was given to zinc-deficient (ZD) rats to determine whether it prevents the intestinal damage usually observed under these conditions. Weanling male rats were given free access to a ZD diet (2 mg zinc/kg), whereas control rats including pair-fed (PF) and ad libitum consumption (AL) groups were given a zinc-supplemented (50.8 mg zinc/kg) diet for 4 wk. Half of the ZD rats received L-NAME (0.3 g/L in drinking water) for 3 wk starting at the wk 2 of the deficient period. Plasma zinc concentration in ZD rats was significantly lower (P < 0.05) than that of AL and PF rats. Administration of L-NAME did not alter this concentration. Intestinal zinc concentration did not differ among groups. However, metallothionein-1 (MT-1) mRNA level was significantly lower in the intestine of ZD rats than in AL or PF rats. Treatment of ZD rats with L-NAME did not affect this level. Intestinal microvascular permeability evaluated by Evans blue showed significantly higher extravasation in ZD rats than in AL rats, whereas L-NAME administration inhibited the extravasation. Expression of inducible NOS mRNA was observed in intestine of ZD but not of AL or PF rats, and there was no significant difference between ZD rats, regardless of L-NAME treatment. The activity ratio of inducible NOS to total NOS in ZD rats not receiving L-NAME was significantly higher than that in AL rats or ZD rats treated with L-NAME (P < 0.05). The number of apoptotic-positive and goblet cells in intestinal villi was significantly higher in ZD rats compared with AL or PF rats. L-NAME administration in ZD rats reversed this effect. These results indicate that inhibition of NOS ameliorates zinc deficiency-induced intestinal damage in rats.     

A high dietary lipid intake during pregnancy and lactation enhances mammary gland lipid uptake and lipoprotein lipase activity in rats.

Rats fed a diet with high fat concentration produce larger amounts of milk with a higher lipid concentration than rats fed a lower fat diet. This investigation was designed to study the relationship between dietary fat intake, mammary gland lipid uptake and lipogenesis in rat dams fed, during pregnancy and lactation, one of two purified diets, with equal energy density, containing 2.5 (LL) or 20 g fat/100 g diet (HL). Milk lipid concentration and fatty acid composition were determined at d 14 of lactation. Mammary gland lipogenesis, lipoprotein lipase (LPL) activity and the uptake of [1-(14)C]triolein by the mammary gland and its transfer to the pups was measured. The intestinal absorption of oral (14)C-lipid, (14)CO(2) production and the amount of (14)C-lipid transferred to the pups (milk clot + pups carcass) were significantly higher in the HL group than in the LL group (P < 0.05). Mammary gland lipogenesis was 75% lower and LPL activity was 30% higher in the HL group (P < 0.05). Medium-chain fatty acids (C6-C14) excretion was 46% lower and that of long-chain fatty acids was 142% (P < 0.001) higher in the HL group than in the LL group. The higher milk lipid excretion in the rats fed a high-fat diet resulted from a larger uptake of dietary lipid by the mammary gland, indicated by a larger transfer of (14)C-lipid to the pups and by a higher LPL activity in the mammary gland.     

下丘脑腹内侧核损伤性肥胖大鼠急性期脂肪代谢相关酶活性研究

目的 :　观察下丘脑腹内侧核损伤性肥胖大鼠在自由进食状态下脂肪合成与分解代谢的变化。方法 :　雌性 SD大鼠分为下丘脑腹内侧核损伤肥胖组 (VMH)和下丘脑腹内侧核非损伤对照组 (假手术 ) ,于下丘脑腹内侧核手术 1 w后 ,留取血样、肝脏、皮下脂肪、子宫外周和肠系膜脂肪组织以及腓肠肌分别测定生化指标、脂肪合成酶和分解酶活性。结果 :　在自由进食状态下VMH血清胰岛素水平显著高于对照组 ,而血浆游离脂肪酸显著低于对照组。大鼠肝脏微粒体甘油三酯转运蛋白 (MTP)、肝脏磷脂酰磷酸水解酶 (PAP)、苹果酸酶 (ME)、葡萄糖 - 6-磷酸脱氢酶(G6PDH)以及子宫外周脂肪组织 ME和肠系膜脂肪组织 ME、G6PDH的活性均高于对照组。与对照组相比 ,VMH组子宫外周、肠系膜脂肪组织和腓肠肌激素敏感脂酶 (HSL)活性没有变化 ,皮下脂肪组织的 HSL活性升高。在 VMH组 ,皮下脂肪组织、子宫外周脂肪组织、肠系膜脂肪组织以及腓肠肌中的脂蛋白脂酶活性均显著升高。结论 :　下丘脑腹内侧核损伤性肥胖大鼠自由进食状态下肝脏合成和转运甘油三酯能力增强 ,脂肪组织如子宫外周和肠系膜脂肪组织的脂质合成和储存增多 ;而外周组织如肌肉组织和皮下脂肪组织的脂肪分解和动员也增加     

Neonatal overfeeding causes higher adrenal catecholamine content and basal secretion and liver dysfunction in adult rats

Purpose

Rats that are overfed during lactation exhibit neonatal hyperleptinemia and higher visceral adiposity, hypertension, higher liver oxidative stress and insulin resistance in the liver as adults. Previously, we demonstrated that neonatal hyperleptinemia is associated with adrenal medullary hyperfunction, hypertension and liver steatosis in adulthood. Therefore, we hypothesised that adrenal and liver functions are altered in adult obese rats that were overfed during lactation, which would underlie their hypertension and liver alterations.

Methods

The litter size was reduced from ten to three male pups on the third day of lactation until weaning (SL) to induce early overfeeding in Wistar rats. The control group had ten rats per litter (NL). Rats had free access to standard diet, and water after weaning until the rats were 180 days old.

Results

The SL group exhibited higher adrenal catecholamine content (absolute: +35% and relative: +40%), tyrosine hydroxylase (+31%) and DOPA decarboxylase (+90%) protein contents and basal catecholamine secretion in vitro (+57%). However, the hormones of the hypothalamic-pituitary-adrenal cortex axis were unchanged. β₃-adrenergic receptor content in visceral adipose tissue was unchanged in SL rats, but the β₂-adrenergic receptor content in the liver was lower in this group (?45%). The SL group exhibited higher glycogen and triglycerides contents in the liver (+79 and +49%, respectively), which suggested microesteatosis.

Conclusions

Neonatal overfeeding led to higher adrenomedullary function, but the liver β₂-adrenergic receptor content was reduced. These results may contribute to the hepatic dysfunction characteristic of liver obesity complications.     

Metabolism of different adipose tissues in vivo in the rat

To explore regional differences in triglyceride retention in white adipose tissues of growing male rats, the mass of adipocytes from epididymal, retroperitoneal, inguinal, and mesenteric tissues were followed with time. In order to attempt to explain regional differences, adipose tissue metabolism was studied in vivo and in vitro. (U-14C) oleic acid in sesame oil was given by gastric gavage to conscious male and female rats, and accumulation and half-life of radioactivity measured. Lipoprotein lipase activity and lipolysis were studied in vitro. Adipocyte triglyceride mass increased linearly in all the depots during 4 months of observation.The increase in mass was more pronounced in retroperitoneal (0.31 microg) and epididymal (0.30 microg) than in mesenteric (0.11 microg) or inguinal (0.05 microg) adipocytes. In the fed state label from (U-14C) oleic acid first increased with time in liver, muscle, and adipose tissues. In the liver radioactivity peaked at 4 hours, and was not measurable in either liver or muscle after a time point between 24 hours to 1 week. In contrast label continued to increase in adipose tissues up to about 16 hours to 24 hours, suggesting transfer of label by recirculation from liver and muscle to adipose tissues. Thereafter the radioactivity decreased. When expressed per adipocyte uptake of label was not significantly different between white adipose tissues. The rate of decrease between 7 days and 4 months was, however, more rapid in mesenteric and inguinal than, particularly, epididymal, and, probably, retroperitoneal adipocytes. These results were partly parallel to in vitro data on lipoprotein lipase activity, which was not different between depots, and the rate of lipolysis, which was higher in mesenteric than other adipocytes. These results suggest that differences in weight increase of adipose tissue regions are due mainly to differences in the rate of mobilization of adipocyte triglycerides. When expressed per gram triglyceride, uptake and mobilization of label were clearly more rapid in mesenteric than other white adipose tissues. This is probably explained by a combination of a higher adipocyte density plus the metabolic characteristics of adipocytes in this depot. Since mesenteric adipose tissue is smaller than the other depots studied, the absolute contribution of this tissue to the energy supply of the body is probably not different from that of other adipose tissues, however. A large uptake and short half life was observed in interscapular adipose tissue. This region contains brown adipocytes, and the results therefore suggest that lipid uptake for thermogenic purposes is of a considerable magnitude. It was concluded that among white adipose tissues, the mesenteric tissue has a rapid turnover of triglyceride. This is probably due to a combination of a high density and specific metabolic characteristics of these adipocytes. Factors in the microenvironment of adipocytes probably contribute to the high turnover either directly, or by modification of cellular characteristics.     

Abstracts of Articles on Energy Metabolism and Obesity

The present study investigates fat deposition, variances of fatty acid (FA) composition, and lipogenic enzyme activities through dietary medium- and long-chain triglyceride (MCT and LCT) supplementation in growing rats. Eighteen male Wistar rats were divided into three groups and fed isocalorically for 4 weeks with control (based on AIN 76), MCT (C8:0 26%), or LCT (corn oil 25%) diets. Compared to the control group with 0.28 +/? 0.01, feed efficiency was lower in the MCT rats and greater in the LCT rats (0.24 +/? 0.01 and 0.33 +/? 0.01, respectively). Weights of perirenal and epididymal adipose tissue pads of the MCT rats were similar to those of the control group, but were significantly lower than those of the LCT group. Whole-body carcass components data of MCT rats showed the decrease in moisture and protein contents compared to those of control and LCT rats. Fat content of LCT rats was 25-30% higher than those of the MCT and control group. Glucose-6-phosphate dehydrogenase, citrate cleavage enzyme, and malic enzyme activities of liver and epididymal adipose tissue were markedly low in LCT rats. In the MCT group, however, lipogenic enzyme activities were not suppressed, and malic enzyme activity was drastically increased. FA composition of whole-body triglycerides and epididymal adipose tissue in MCT rats showed that C16:0 and C16:1 levels were higher than those of the LCT rats. In contrast, FA composition of the LCT group presented high C18:2 content.(ABSTRACT TRUNCATED AT 250 WORDS)     

饲料锌过量对幼鼠脑发育及学习记忆的影响及其机理探讨

目的观察锌过量对幼鼠脑发育和学习记忆行为的影响。方法从哺乳期开始建立过量锌幼鼠模型,采用电镜观察、神经生化和神经行为观察等方法。结果随饲料锌含量的增加幼鼠大脑及海马重量减少,血清及海马锌增高。过量锌１、２组（ＺＥ１、ＺＥ２组）幼鼠主动回避反应（ＡＡＲ）习得率及活动明显低于自由喂养组（ＡＬ组）及ＺＥ２组的配对组（ＰＦ组）,ＺＥ２组的恢复组（ＺＥ２Ｒ组）ＡＡＲ习得率也明显低于ＡＬ和ＰＦ组,但明显高于ＺＥ２组。ＰＦ组与ＡＬ组ＡＡＲ习得率差异无显著性,但活动较ＡＬ组多。ＺＥ２组海马一氧化氮含量增加而生长抑素含量减少,脑组织兴奋性氨基酸和抑制性氨基酸总量增高,尤其是谷氨酸增高更为明显。ＺＥ２组海马ＣＡ１区神经元、胶质细胞及细胞器均有不同程度变性、坏死,突触小泡破裂。结论过量锌饲料明显影响幼鼠脑发育和功能,其机理是多方面的