Effects of isoprothiolane and phytosterol on lipogenesis and lipolysis in adipocytes from rats of dietary fat necrosis

To study effects of isoprothiolane and phytosterol on dietary fat necrosis, 3 groups of rats were fed hardened-tallow (HT) diet. Two groups of rats received either isoprothiolane (50 mg/kg) or phytosterol (20 mg/kg) orally once a day consecutively for 10 weeks. One group of rats received standard diet (CE-2) as a control. Fat necrotic lesions were observed in epididymal and perirenal adipose tissues from all rats in the 3 groups fed HT diet. Rats with fat necrosis were characterized by visceral type obesity and saturation in fatty acid composition of triglyceride in adipose tissue. The highest glucose conversion to total lipids was seen in adipocytes from the rats given phytosterol. There was no lipolytic response to epinephrine stimulation (1-100 microM) in adipocytes from the rats given only HT diet, while similar response of adipocytes from the 2 groups treated with either drug to those from the rats fed standard diet was observed. The levels of total saturated fatty acids of phospholipid in adipose tissue from the rats given either drug were lower than that of the rats given only HT diet. These data suggest that either drug alters fatty acid composition of phospholipid in fat cell membrane and enhances lipolysis of the cells.     

Adipogenic differentiation state-specific gene expression as related to bovine carcass adiposity

Genetic regulation of the site of fat deposition is not well defined. The objective of this study was to investigate adipogenic differentiation state-specific gene expression in feedlot cattle (>75% Angus; <25% Simmental parentage) of varying adipose accretion patterns. Four groups of 4 steers were selected via ultrasound for the following adipose tissue characteristics: low subcutaneous-low intramuscular (LSQ-LIM), low subcutaneous-high intramuscular (LSQ-HIM), high subcutaneous-low intramuscular (HSQ-LIM), and high subcutaneous-high intramuscular (HSQ-HIM). Adipose tissue from the subcutaneous (SQ) and intramuscular (IM) depots was collected at slaughter. The relative expression of adipogenic genes was evaluated using quantitative PCR. Data were analyzed using the mixed model of SAS, and gene expression data were analyzed using covariate analysis with ribosomal protein L19 as the covariate. No interactions (P > 0.10) were observed between IM and SQ adipose tissue depots for any of the variables measured. Therefore, only the main effects of high and low accretion within a depot and the effects of depot are reported. Steers with LIM had smaller mean diameter IM adipocytes (P < 0.001) than HIM steers. Steers with HSQ had larger mean diameter SQ adipocytes (P < 0.001) than LSQ. However, there were no differences (P > 0.10) in any of the genes measured due to high or low adipose accretion. Preadipogenic delta-like kinase1 mRNA was greater in the IM than the SQ adipose tissue; conversely, differentiating and adipogenic genes, lipoprotein lipase, PPARγ, fatty acid synthetase, and fatty acid binding protein 4 were greater (P < 0.001) in the SQ than the IM depot. Intramuscular adipocytes were smaller than SQ adipocytes and had greater expression of the preadipogenic gene, indicating that more hyperplasia was occurring. Meanwhile, SQ adipose tissue contained much larger (P < 0.001) adipocytes that had a greater expression (P < 0.001) of differentiating and adipogenic genes than did the IM adipose tissue, indicating more cells were undergoing differentiation and hypertrophy. Adipogenic differentiation state-specific gene expression was not different in cattle with various phenotypes, but adipogenesis in the SQ and IM adipose tissues seems to occur independently.     

Insulin and dexamethasone regulate stearoyl-CoA desaturase mRNA levels and fatty acid synthesis in ovine adipose tissue explants

Sheep adipose tissue explants were maintained in culture for 24 h in the presence of insulin, dexamethasone, or insulin and dexamethasone, and stearoyl-CoA desaturase (SCD) messenger RNA (mRNA) levels and fatty acid synthesis were measured. Insulin increased SCD mRNA levels (P = 0.008) and synthesis of both saturated (P = 0.07) and unsaturated (P < 0.001) fatty acids but had the greatest effect on unsaturated fatty acid synthesis, resulting in the overall production of a greater (P < 0.001) proportion of monounsaturated fat. Dexamethasone, alone, had the opposite effect but actually potentiated the effect of insulin in stimulating SCD expression and both saturated and monounsaturated fatty acid synthesis, without affecting the relative proportions of each. Across adipose tissue depots, the effect of hormones was similar, although the increase in SCD mRNA levels (P = 0.008) and monounsaturated fatty acid synthesis (P < 0.001) was greater in subcutaneous adipose tissue than in the internal (omental and perirenal) depots. These data clearly show that, in ovine adipose tissue, changes in SCD gene expression in response to insulin and dexamethasone are associated with changes in monounsaturated fatty acid synthesis and suggest that it may be possible to develop strategies to manipulate sheep tissues to produce a less-saturated fatty acid profile.     

The effect of dietary copper on the composition of adipose tissue triglycerides in the broiler chicken

The subcutaneous adipose tissue of male broiler chickens fed diets containing either 5 ppm or 227 ppm of added copper was examined for its fatty acid composition and composition of triglyceride species. Small increases in monoenoic fatty acids at the expense of saturated fatty acids were found in birds fed high levels of copper. Significant increases in the triglyceride containing two monoenoic and one saturated fatty acids occurred and these replaced triglycerides composed to two saturated and one monoenoic fatty acids. These changes did not lead to changes in the melting properties of the fat.     

Acetyl-CoA carboxylase and fatty acid synthase activity and immunodetectable protein in adipose tissues of ruminants: effect of temperature and feeding level

To gain insights into the regulation of fat synthesis, we have investigated the effect of cold environmental exposure and feed restriction of sheep on activity and immunodetectable protein content of acetyl-CoA carboxylase (ACC) and fatty acid synthase in adipose tissue. Subcutaneous and mesenteric adipose tissues were collected at slaughter from sheep exposed to either cold (0+/-2 degrees C) or warm (23+/-2 degrees C) environment, and given either ad libitum or restricted access to feed for three 5-wk periods. Acetyl-CoA carboxylase was isolated from frozen adipose tissue samples and activity determined as the rate of incorporation of H14CO3- into acid stable malonyl-CoA. Cold exposure and feed restriction reduced (P < .05) ACC activity in the two adipose tissue depots. Western blot analysis with peroxidase-conjugated streptavidin showed that both adipose tissue depots express a single isoform of ACC. In s.c. adipose tissue, cold exposure increased (P < .05) ACC protein abundance, which is opposite to the change in activity. However, feed restriction reduced immunodetectable ACC protein. There was no significant effect of environment or feeding level on ACC protein abundance in mesenteric tissue. Fatty acid synthase activity determined in ammonium sulfate extract by measuring the malonyl-CoA- and acetyl-CoA-dependent oxidation of NADPH was decreased (P < .05) by feed restriction in both s.c. and mesenteric tissues. Cold exposure reduced fatty acid synthase activity in s.c. but not in mesenteric tissue. There was no effect of environment on fatty acid synthase protein abundance in either adipose tissue depot. However, feed restriction significantly reduced fatty acid synthase protein abundance in the two depots. The data suggest that feed restriction and exposure of ruminants to cold environmental conditions may significantly down-regulate the activity of key lipogenic enzymes.     

Organic acids in diets for entire male pigs

The aim of this study was to investigate the effect of organic acids in diets for entire male pigs on growth performance, composition of microbiota in the gastrointestinal tract (GIT), on concentration of skatole and indole in digesta, plasma and adipose tissue, and concentration of volatile fatty acids (VFA) in digesta. Restrictively-fed pigs (n = 60) (28 and 113 kg initial and final BW, respectively) were used. The dietary treatments consisted of a basal diet and the basal diet added either 1.0% formic acid, 0.85% benzoic acid, 0.85% sorbic acid, 1.2% fat coated Ca-butyrate or 1.5% fat and inulin coated Ca-butyrate. All levels of organic acids corresponded to 0.85% of pure acid. Digesta samples for microbiological examinations were taken from the proximal jejunum, colon descendens, and rectum. Digesta samples for skatole, indole and VFA analyses were taken from colon descendens. The results showed that the addition of organic acids to diets had no effect on daily weight gain or feed intake, but formic, benzoic and sorbic acid tended to improve FCR of pigs compared with the control pigs. Organic acid supplementation did not affect levels of skatole, indole, or VFA in the digesta or levels of skatole or indole in adipose tissue compared with the control. Plasma skatole levels were reduced in pigs fed diets containing formic and benzoic acid compared with the control pigs. Pigs fed organic acids had lower levels of coliforms, enterococci and lactic acid producing bacteria in all three sampling sites of the GIT. Supplementing diets with organic acids did not affect levels of skatole in digesta or adipose tissue of entire male pigs.     

动物脂肪酸合成酶(FAS)基因表达的调控

脂肪酸合成酶(FAS)催化乙酰辅酶A和丙二酸单酰辅酶A合成脂肪酸 ,从而在动物体脂沉积中发挥重要作用。动物体内脂肪酸合成酶受激素和日粮因素的调控。本文介绍了几种激素及日粮营养成分对脂肪酸合成酶的活性和基因表达调控的影响及其可能的作用机理 ,并就脂肪酸合成酶基因表达调控在实际生产中的应用进行了探讨。     

Feeding lambs high-oleate or high-linoleate safflower seeds differentially influences carcass fatty acid composition

Our objective was to determine effects of dietary high-oleate (Oleate; 76% 18:1) or high-linoleate (Linoleate; 78% 18:2) safflower seeds on fatty acids in muscle and adipose tissue of feedlot lambs. White-faced ewe lambs (n = 36) were fed a beet pulp, oat hay, and soybean meal basal diet (Control), blocked by BW, and allotted randomly to dietary treatments. Cracked safflower seeds were used in isocaloric and isonitrogenous replacement of beet pulp, oat hay, and soybean meal so that Oleate and Linoleate diets contained 5.0% additional fat. Fatty acids were determined in semitendinosus, longissimus dorsi (longissimus), and adipose tissue from the tail head (tailhead adipose tissue), adjacent to the 12th rib (s.c. adipose tissue), and kidney and pelvic fat (KPH adipose tissue) depots. Fatty acid data were analyzed within muscle and adipose tissue as a split-block design. Single degree of freedom orthogonal contrasts were used to compare treatment effects. Average daily gain, feed efficiency, and carcass characteristics did not differ (P = 0.15 to 0.96) across dietary treatments. Adipose tissue saturated fatty acids were greater (P = 0.04) for Controls but were not different (P = 0.36) in muscle. Trans-vaccenic acid (18:1(trans-11)) increased (P < 0.0001) with safflower supplementation and was greater (P < 0.0001) in Linoleate than in Oleate for both tissue types. Linoleate lamb had greater (P < 0.0001) PUFA than Oleate lamb in muscle and adipose tissue. Conjugated linoleic acids (CLA; cis-9, trans-11 and trans-10, cis-12) were greater (P < 0.0001) in muscle and adipose tissue of lambs fed safflower seeds. Lambs fed Linoleate had greater (P < 0.0001) CLA in adipose tissue and muscle than lambs fed Oleate. Saturated fatty acids were greater (P < 0.0001) in s.c. adipose tissue than in tailhead adipose tissue. Mono- and polyunsaturated fatty acids were greater (P < 0.0001) in tailhead adipose tissue than in s.c. adipose tissue. Weight percentages of 18:1(trans-11) ranked tailhead adipose tissue = KPH adipose tissue > s.c. adipose tissue and semitendinosus > longissimus, whereas CLA ranked tailhead adipose tissue > s.c. adipose tissue > KPH adipose tissue and semitendinosus > longissimus. Feeding mono- and polyunsaturated fatty acids increased tissue 18:1(trans-11) and CLA, which is a favorable change in regard to current human dietary guidelines.     

Effects of body condition score at parturition and postpartum supplemental fat on adipose tissue lipogenic activity of lactating beef cows

Three-year-old Angus x Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of initial BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of initial BW) at parturition were used in a 2-yr experiment (n = 36/yr) to determine the effects of BCS at parturition and postpartum lipid supplementation on cow adipose tissue lipogenesis. Beginning 3 d postpartum, cows within each BCS were randomly assigned to be fed hay and a low-fat control supplement or supplements with either cracked high-linoleate safflower seeds or cracked high-oleate safflower seeds until d 60 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed diets provided 5% DMI as fat. Adipose tissue biopsies were collected near the tail-head region of cows on d 30 and 60 of lactation. Dietary treatment did not affect (P > or = 0.43) adipose tissue lipogenesis. Body condition score at parturition did not affect acetate incorporation into lipid (P = 0.53) or activity of acetyl CoA carboxylase (P = 0.77) or fatty acid synthase (P = 0.18). Lipoprotein lipase activity and palmitate incorporation into triacyl-glycerol tended to be greater (P = 0.06), and palmitate esterification into total acylglycerols was greater (P = 0.01) in cows with a BCS of 4 at parturition. Mean activity of acetyl-CoA carboxylase (P < 0.001), lipoprotein lipase (P = 0.01), and rate of palmitate incorporation into monoacylglycerol (P = 0.02), diacylglycerol (P = 0.001), triacylglycerol (P = 0.003), and total acylglycerols (P = 0.002) were greater at d 30 than d 60, suggesting a greater proclivity for fatty acid biosynthesis and esterification by adipose tissue at d 30 of lactation. Although dietary lipid supplementation did not affect adipose tissue lipogenesis, results suggest that cows with a BCS of 4 at parturition have a greater propensity to deliver exogenously derived fatty acids to the adipocyte surface and incorporate preformed fatty acids into acylglycerols as stored adipocyte lipid. Additionally, cows in early lactation seemed to be able to synthesize and incorporate more fatty acids into stored lipid than cows during peak lactation.     

The effect of porcine somatotropin supplementation in pigs on the lipid profile of subcutaneous and intermuscular adipose tissue and longissimus muscle.

The effect of porcine somatotropin (pST) on the lipid profiles of adipose tissue and muscle was investigated. Sixteen crossbred barrows were injected daily with either 3 mg of pST or a placebo. After slaughter, total lipid and fatty acid composition of raw subcutaneous (SC) adipose and intermuscular (IM) adipose tissue and longissimus muscle were determined. The SC adipose tissue from pST-treated pigs had a 7.5% decrease in total lipid content; specific fatty acids 16:0, 18:0, and 18:1(n-9)c decreased most. The IM fat from pST-treated pigs had lower levels of 16:0 and 20:0. There was no effect of pST treatment on the lipid profile of the longissimus muscle. The data suggest that pST treatment produces small but significant changes in the saturated fatty acid content of adipose tissue in pigs.     

Influence of rapeseed meal, whole rapeseed, and soybean meal on fatty acid composition and cholesterol content of muscle and adipose tissue from ram lambs.

Twenty-four Suffolk x Hampshire ram lambs (average 46 kg) were assigned to one of three diets containing rapeseed meal (RM), soybean meal (SBM), or whole rapeseed-soybean meal (RSSBM) as the protein source. Diets contained 75% roughage, 14% CP and 2.0 Mcal of ME/kg and lambs were allowed ad libitum access to diets for 35 d. Lipid composition of the longissimus, semimembranosus, and triceps brachii muscles and their corresponding s.c. adipose tissue was determined by gas-liquid chromatography (GLC). The total lipid content in either muscle or subcutaneous fat was not different (P greater than .01) by diet. In lean tissue, palmitic and palmitoleic acids were higher and stearic acid was lower (P less than .01) in rams fed RM than in rams fed RSSBM or SBM, regardless of anatomical location. In the s.c. adipose tissue, the amounts of myristoleic, pentadecylic, and palmitoleic acids were lower and the amount of stearic acid was higher (P less than .01) in rams fed RSSM than in those fed RM or SBM, regardless of anatomical location. The semimembranosus and triceps brachii muscles from all treatments contained 12 to 19% more polyunsaturated fatty acids (PUFA) than the longissimus muscle. The cholesterol content of the three muscles was highest in SBM-fed lambs, lowest in RM-fed lambs, and intermediate in RSSBM-fed lambs. These results demonstrate that dietary treatments of the types used in the present study elicit changes in fatty acid composition of both adipose and muscle tissue without affecting the quantity of total lipid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of isoprothiolane and phytosterol on adipocyte metabolism and fatty acid composition of serum and tissue lipids in rats.

Isoprothiolane at a dose of 250 mg/kg or phytosterol 50 mg/kg was orally administered to rats once a day for 2 weeks. Basal [U-14C]glucose conversion rate to total lipids in isolated adipocytes of the rats was significantly decreased by treatment with isoprothiolane (54%) or phytosterol (82%). Adipocytes from the rats with isoprothiolane released less glycerol than those from control rats only at an epinephrine concentration of 10 microM. The serum level of total cholesterol was depressed by phytosterol ingestion. The level of non-esterified fatty acids (NEFA) was increased by isoprothiolane. Desaturation in fatty acid composition of phospholipid or cholesterol ester was observed in serum, liver and adipose tissue of the rats treated with either drug. These results suggest that either drug may have common effects by preventing lipid deposition into adipocytes and accelerating fatty acid desaturation in tissue lipids.     

Comparative evaluation of rumen-protected fat, coconut oil and various oilseeds supplemented to fattening bulls. 2. Effects on composition and oxidative stability of adipose tissues.

The effects of five different dietary fat supplements on fatty acid composition and oxidative stability of subcutaneous and kidney fat were evaluated in 36 Brown Swiss bulls and compared to a low fat diet in a monofactorial design. The following fat supplements were provided as additional fat at 30 g per kg feed dry matter: crystalline rumen-protected fat, coconut oil, and three types of crushed whole oilseeds (rapeseed, sunflower seed and linseed). Adipose tissues reflected differences (P < 0.05) in dietary fatty acid composition although to a lower extent. Using protected fat, which contained elevated levels of trans fatty acids, and sunflower seed, containing a high proportion of linoleic acid, significantly increased C18:1 trans fatty acid proportion in the adipose tissues. The use of sunflower seed increased conjugated linoleic acid. The oilseeds resulted in lower amounts of C16:0 in favour of C18:0. Except for linseed, all fat supplemented groups improved oxidative stability of adipose tissues as compared with control. This was explained by lower proportions of unsaturated fatty acids in adipose tissue (protected fat), by elevated alpha-tocopherol contents (rapeseed, sunflower seed) or by a combination of both (coconut oil). Fat colour remained unaffected by treatments. Compared to other fat supplements oilseeds, especially sunflower seed and rapeseed, can therefore be recommended to be fed to bulls in order to increase the proportions of C18 unsaturated fatty acids in adipose tissues and to maintain or improve oxidative stability.     

Effects of dietary energy level on lipid metabolism‐related gene expression in subcutaneous adipose tissue of Yellow breed × Simmental cattle

This study was conducted to estimate the effect of dietary energy level on lipid metabolism‐related gene expression of subcutaneous adipose tissue in Yellow breed × Simmental cattle. The experiment was conducted for 60 days. The results showed that final weight, average daily gain, average backfat thickness, (testicles + kidney + pelvic) fat percentage and subcutaneous fat percentage in the high and medium energy groups were significantly higher than in the low‐energy group but that the feed conversion ratio was significantly lower. The glucose, triglycerides, cholesterol, high‐density lipoprotein and low‐density lipoprotein in the high‐energy group were significantly higher than in the low‐energy group. With dietary energy increasing the activities of lipoprotein lipase (LPL), fatty acid synthase (FAS) and acetyl‐CoA carboxylase (ACC) significantly increased, whereas hormone‐sensitive lipase (HSL) and carnitine palmitoyltransferase‐1 (CPT‐1) significantly diminished. Peroxisome proliferator‐activated receptor γ (PPARγ), LPL, FAS, sterol regulatory element binding protein 1 (SREBP‐1), ACC, stearoyl‐CoA desaturase (SCD) and adipocyte‐fatty acid binding proteins (A‐FABP) gene expression were significantly increased by dietary energy increasing, and HSL and CPT‐1 gene expression were significantly decreased. These results indicated that with dietary energy increasing, the subcutaneous fat accumulation mainly increased due to adipose tissue lipogenic gene expression and decreased lipolytic gene expression.