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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fat cells isolated from rat epididymal adipose tissue were incubated with albumin-bound [14C]palmitate. Incorporation of 14C into 14CO2 and glycerides was measured. Some evidence is presented to suggest that the exogenous palmitate pool is in isotopic equilibrium with intracellular precursors for these metabolic processes. Precautions were taken to minimize dilution of the exogenous palmitate pool by fatty acids released from the cells. 14CO2 production from [1-14C]palmitate was 3 times that from [16-14C]palmitate. Octanoate increased this differential oxidation of palmitate carbons and also inhibited palmitate oxidation without similarly affecting esterification. Glucose increases palmitate esterification in cells from fed or starved rats. Insulin potentiated this effect of glucose. Glucose influenced palmitate oxidation in a more complex manner, dependent upon the glucose concentration. Both the observation that esterification constitutes 99% of the metabolic flux of fatty acid and the manner in which glucose, insulin, or starvation influence palmitate esterification and oxidation suggested that factors controlling esterification may alter oxidation as a secondary effect, but not vice versa. It is suggested that oxidation and esterification compete for a single intracellular precursor, possibly extramitochondrial long chain fatty acyl CoA.
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PMID:Factors affecting fatty acid oxidation in fat cells isolated from rat white adipose tissue. 96 42

The present study was undertaken to investigate the effects of dietary medium and long chain triglycerides (MCT and LCT) on fat deposition and fatty acid composition of adipose tissues of rats. Twenty-seven Wistar strain male rats were divided into three groups and fed semisynthetic experimental diets: Basal (AIN 76), MCT (basal+C8:0 10%), LCT (basal+corn oil 10%). Feed intake was measured every day and body weight was measured once a week. At the beginning, 4th and 8th week of experimental feeding, 3, 12, 12 rats were slaughtered, respectively. Liver, perirenal and epididymal adipose tissue pads were weighted and their fatty acid composition was determined. Chemical composition of wholebody carcass was measured. Body weight gain was greater in rats fed the LCT diet than in rats fed the basal and MCT diets. Feed intakes were decreased in rats fed the MCT and LCT diets compared to that of the basal group. Subsequently, when compared to the basal group rats, feed efficiencies in rats fed the MCT and LCT diets were improved at the level of 6 and 14% for 4 weeks, and then 17 and 24% for 8 weeks, respectively. The weight of perirenal and epididymal adipose tissue pads tended to be larger in rats fed the MCT and LCT diets than in the basal group, although not significant. There were not significant differences in wholebody composition among the three groups. But it appeared that in rats fed the MCT diet, moisture content tended to be decreased and crude protein content increased compared to the LCT group rats. Fatty acid composition of the rats fed the LCT diet showed a good reflection of dietary fatty acid composition. Unlike LCT, little of medium chain fatty acid (MCFA) itself were incorporated into liver or adipose tissues. However, it seems that fat deposition of the MCT group was accomplished not by incorporation of dietary fatty acids but by de novo fatty acids synthesis.
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PMID:The influence of dietary medium and long chain triglycerides on growth performances and fat deposition in growing rats. 150 19

The authors report a review on the L-carnitine effects on the male genital tract. L-carnitine represents a cofactor in the transport of long chain fatty acids inside mitochondria and their subsequent oxidation. Therefore, its main role is that of intramitochondrial vehicle of acyl groups. In particular, the effects of L-carnitine on the male genital function seem connected mainly with the high concentration of L-carnitine in the epididymis; the uptake of the L-carnitine from the blood is an active, in part androgen-dependent, mechanism. Moreover, epididymal spermatozoa are able to concentrate L-carnitine (while they become progressively more impermeable to such a substance) during their passage from the caput to the cauda epididymis. The main function of the L-carnitine in the epididymis is to give to the spermatozoa an energetic substrate. In fact, this function should be of great importance since the epididymal spermatozoa employ fatty acid oxidation for their energy metabolism; on the contrary, the ejaculated sperm employ glycolytic process. As a consequence of the above-mentioned effects of L-carnitine the dosage of this substance in the evaluation of the integrity of the processes of maturation of the spermatozoa was proposed. Finally, there is growing interest in the use of L-carnitine as a therapeutic tool in some forms of male infertility.
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PMID:[Metabolism and action of L-carnitine: its possible role in sperm tail function]. 150 74

A movement pattern known as hyperactivation has been observed among sperm recovered from the periovulatory oviduct of several species. In culture medium, hyperactivated sperm swim in a pattern that is far less progressive than that of freshly ejaculated sperm. In the oviduct, sperm encounter highly viscoelastic substances, such as mucus and the cumulus matrix. We have previously reported that hyperactivated hamster sperm become more progressive in vitro when the viscosity of medium is increased. In the present study, we tested the effect of increasing the viscosity and viscoelasticity of the medium on the swimming progressiveness of mouse sperm. Caudal epididymal sperm were incubated in a medium that produced hyperactivated motility in 60 min. Swimming velocities of sperm incubated for 60 min were compared with those of fresh sperm after addition of one of the following to culture medium: solutions of 1.8% methylcellulose (high viscosity), 1.8% long chain polyacrylamide (high viscoelasticity), or culture medium alone (low viscosity). In culture medium, hyperactivated sperm had significantly lower mean straight-line velocities than fresh sperm (p = 0.004); this difference disappeared in methylcellulose (p = 0.085) and was reversed in polyacrylamide (p = 0.004). This and other velocity measurements indicated that hyperactivated mouse sperm penetrate viscoelastic media more efficiently than fresh sperm and therefore may be more efficient at penetrating oviductal mucus and cumulus matrix in vivo.
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PMID:Hyperactivation enhances mouse sperm capacity for penetrating viscoelastic media. 157 67

It is generally agreed that thyroid hormone stimulates the hepatic synthesis of long chain fatty acids in the rat. However, there are conflicting data about its effects in white adipose tissue, while in brown adipose tissue, lipogenic rates are highest in hypothyroid animals. We have systematically examined the effect of thyroid state on lipogenesis in different rat tissues. Fatty acid synthesis was assessed in vivo, using the incorporation of tritiated water. Hepatic lipogenesis was induced 16-fold between hypothyroid (4.1 +/- 0.6 microns H incorporated/g.h) and hyperthyroid rats (66.5 +/- 13.2 microns H/g.h). Kidney and heart were much less lipogenically active, but also responded positively to thyroid hormone. Both hyper- and hypothyroidism diminished fatty acid synthesis in retroperitoneal fat and had similar, although not significant, effects in epididymal fat. However, epididymal adipocytes, taken from hyperthyroid rats and cultured in vitro, were 3 times more lipogenically active than cells from either hypo- or euthyroid animals. Lipogenesis in sc fat from hyperthyroid rats was enhanced when calculated per g tissue, but was not different when expressed per whole tissue. In brown adipose tissue, lipogenesis was inversely related to thyroid hormone status. Fatty acid synthesis in brain, lung, skin, and bone and muscle did not respond to changes in thyroid state. TLC confirmed that greater than 90% of the incorporated tritium was in fatty acids. Thus, in hypothyroid animals, lipogenesis primarily occurs in skin, bone, muscle, and other nonresponsive organs, whereas in hyperthyroid rats, the liver alone constitutes almost half of all fatty acid synthesis. The fatty acid synthetic pathway provides an excellent model for examining the tissue-specific regulation of gene expression by thyroid hormone.
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PMID:Tissue-specific regulation of fatty acid synthesis by thyroid hormone. 173 12

Effects of feeding early in life a diet high in either long chain (LCT) or medium chain triglyceride (MCT) were studied on the development of adipose tissue in post-weanling rats. The diets were similar in calorie distribution and identical in nutrients except for type of fat. The caloric distribution of the two diets by percent was LCT (corn oil)/protein/carbohydrate, 70/18/12 and MCT/corn oil/protein/carbohydrate, 66/4/18/12. Male littermates with less than 5% weight difference were pair-fed the two diets randomly at age 18-20 days. One-fourth of the rats were killed at 10, 16, 22 and 28 weeks of age and analyzed for adipose depots and adipose tissue cellularity. Results showed that the LCT-fed rats were significantly heavier, with larger epididymal, retroperitoneal, omental and subcutaneous fat pads than the respective pair-fed MCT rats. Also, LCT-fed rats had larger size and number of adipocytes than MCT-fed littermates. It is concluded that the type of fat in the diet, namely LCT or MCT, when fed early in life can influence the development of adipose tissue. MCT appears less lipogenic than LCT. The mechanism for the diminished adiposity of MCT-fed rats is related to extensive oxidation of MCT and its enhancement of thermogenesis leading to lessened energy efficiency.
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PMID:Medium chain triglyceride in early life: effects on growth of adipose tissue. 361 74

The influence of dietary lipid on fatty acid synthesis in brown adipose tissue has been investigated by feeding different high-fat diets to cold-acclimated mice for a period of 2 weeks. Fatty acid synthesis was measured in vivo with 3H2O, and the fats used in the study were maize oil, beef tallow and medium chain triacylglycerol oil. In the mice fed the maize oil and the beef tallow diets fatty acids synthesis was inhibited in all tissue examined--interscapular brown adipose tissue, epididymal white adipose tissue, the liver and the carcass. Synthesis was more inhibited, however, in brown adipose tissue than in other tissues, and the inhibition was greater on the maize oil diet than on the beef tallow. The medium chain triacylglycerol oil had no inhibitory effect on fatty acid synthesis in any tissue, and hepatic synthesis was even elevated on this diet. It is concluded that fatty acid synthesis in brown adipose tissue, as in other lipogenic tissues, is subject to strong suppression by dietary long chain fatty acids, and particularly by linoleic acid.
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PMID:Suppression of fatty acids synthesis in brown adipose tissue of mice fed diets rich in long chain fatty acids. 729 53

Albumin is the major carrier of long chain free fatty acids, that are known to be heavily utilized by fat cells. To investigate the cellular structures involved in the interaction of albumin with preadipocytes, precursor fat cells isolated from rat epididymal fat pads were cultured in Dulbecco's modified Eagle's medium supplemented with 5% fetal calf serum and antibiotics. Cell differentiation was induced by 1.7 nM insulin added to the culture medium. The ensuing cells in various stages of differentiation were incubated with albumin, alone or bearing oleic acid, adsorbed to 5 nm gold particles (Alb-Au or Alb-OA-Au) for 10 min at 37 degrees C. As control, polyethyleneglycol-gold and IgG-gold complexes were used in same conditions. After extensive washing, the cell monolayer was fixed in 2.5% glutaraldehyde, and processed for electron microscopy. Examination of thin sections and morphometric analysis showed that: a) in the process of adipogenesis induced in vitro four cell types were simultaneously present: fibroblast-like cells (F), early adipocytes (EA), adipocytes (A) and aged adipocytes (AA); b) upon incubation with Alb-Au, the probe labelled preferentially coated pits and coated vesicles and only some uncoated vesicles; in time the tracer was found in endosomes, occasionally, multivesicular bodies and lysosome-like structures. The binding and uptake was dependent on the stage of cell differentiation, being less pronounced in fibroblast-like cells and increased in later stages (A and AA); c) Alb-OA-Au labelled the same structural features like the Alb-Au (i.e. coated pits and vesicles); however, the binding to the cell membrane was fourfold higher than that of Alb-Au in F and EA stages and was maintained at the same level in A and AA stages; d) control probes were taken up only by adipocytes and aged adipocytes, cells that express a strong phagocytic function for all tracers used. These results indicated that albumin bound to gold and especially albumin-bearing fatty acids-gold, bind preferentially to coated pits and vesicles of preadipocytes. Further internalization of albumin-gold particles seems to be non-specific, since both the probes and the controls adsorbed to gold were delivered to the same endosomal-lysosomal compartment.
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PMID:Cellular structures involved in albumin interaction with preadipocytes in various stages of adipogenesis, in vitro. 801 43

To examine the relationship between the type of dietary fat on liver and adipose tissue metabolism, in this study, fresh weight, protein, DNA, lipid content, and rate of lipogenesis from 3H2O of liver and retroperitoneal (RET) and epididymal (EPI) adipose tissues were assessed in rats fed polyunsaturated omega-6 (PUFA), saturated medium chain (SMC) or saturated long chain (SLC) fatty acid rich chows and control chow (CC). The results obtained indicate that fatty acid rich diets decreased liver fresh weight, protein and DNA content. However, they increased lipid content in liver and carcasses without changing the weight of RET and EPI. The rate of lipogenesis in vivo was increased by SMC and PUFA in liver and RET. These results indicate that not only the lipid content of diet but also the type of fatty acid caused metabolic alterations both in liver and white adipose tissues.
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PMID:Effect of saturated and polyunsaturated fatty acids rich diets on hepatic and adipose tissue lipid metabolism in rats. 889 61

Agonists of peroxisome proliferator-activated receptors (PPARs) have emerged as important pharmacological agents for improving insulin action. A major mechanism of action of PPAR agonists is thought to involve the alteration of the tissue distribution of nonesterified fatty acid (NEFA) uptake and utilization. To test this hypothesis directly, we examined the effect of the novel PPARalpha/gamma agonist tesaglitazar on whole-body insulin sensitivity and NEFA clearance into epididymal white adipose tissue (WAT), red gastrocnemius muscle, and liver in rats with dietary-induced insulin resistance. Wistar rats were fed a high-fat diet (59% of calories as fat) for 3 wk with or without treatment with tesaglitazar (1 micromol.kg(-1).d(-1), 7 d). NEFA clearance was measured using the partially metabolizable NEFA tracer, (3)H-R-bromopalmitate, administered under conditions of basal or elevated NEFA availability. Tesaglitazar improved the insulin sensitivity of high-fat-fed rats, indicated by an increase in the glucose infusion rate during hyperinsulinemic-euglycemic clamp (P < 0.01). This improvement in insulin action was associated with decreased diglyceride (P < 0.05) and long chain acyl coenzyme A (P < 0.05) in skeletal muscle. NEFA clearance into WAT of high-fat-fed rats was increased 52% by tesaglitazar under basal conditions (P < 0.001). In addition the PPARalpha/gamma agonist moderately increased hepatic and muscle NEFA utilization and reduced hepatic triglyceride accumulation (P < 0.05). This study shows that tesaglitazar is an effective insulin-sensitizing agent in a mild dietary model of insulin resistance. Furthermore, we provide the first direct in vivo evidence that an agonist of both PPARalpha and PPARgamma increases the ability of WAT, liver, and skeletal muscle to use fatty acids in association with its beneficial effects on insulin action in this model.
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PMID:Peroxisome proliferator-activated receptor (PPAR) activation induces tissue-specific effects on fatty acid uptake and metabolism in vivo--a study using the novel PPARalpha/gamma agonist tesaglitazar. 1505 48


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