Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A connecting link between carbohydrate and fat metabolism in adipose tissue is theconcentration of alpha-glycerophosphate derived predominantly from the glycolysis ofglucose entering the fat cell. However, several investigators have reported the presence of a glycerol specific kinase in the epidiymal fat-pad of the rat and obob mouse. This enzyme's presence in other mammalian adipose tissue could contribute to the alpha-glycerophosphate pool and thus affect both carbohydrate and fat metabolism within the fat cell. Glycerokinase was demonstrated in isolated fat cells obtained from the subcutaneous, perirenal, epididymal, and dorsal intrascapular brown fat depots of the adultmale rat. It was found to be particularly sensitive to in vivo lipogenic stimuli in both the subcutaneous and the brown adipose tissue and concluded that insulin is involved in adipose glycerokinase stimulation. Therefore, the main function of glycerokinase in normal adipose tissue may be to augment the anabolic action of insulin. It isfurther suggested that deviation from the normal control of this lipogenic enzyme couldlead to a gradual accumulation of fat and eventual obesity.
 ...
PMID:Glycerokinase in mammalian adipose tissue: stimulation by lipogenic substances. 16 85

We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus (1971, J. Biol. Chem. 246, 3885-3894) for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with [32P]ATP and glycerokinase, residual [32P]ATP is hydrolyzed by heating in acid, and free [32P]phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays.
 ...
PMID:Radiometric assays for glycerol, glucose, and glycogen. 281 33

Rates of lipolysis, esterification, and free fatty acid release were estimated in isolated epididymal fat cells prepared from rats fed either ad lib. or with a restricted caloric intake. Basal and epinephrine- or theophylline-stimulated rates of lipolysis correlated positively with cell size in the ad lib.-fed group only. Rates of esterification, both basal and epinephrine-stimulated, correlated positively with cell size in the ad lib.-fed group but negatively in the caloric-restricted group. These findings indicate that nutritional factors can modify any possible influence of adipose cell size on lipolysis and esterification. On the other hand, in both groups of rats, epinephrine- and theophylline-stimulated rates of lipolysis correlated positively with the basal rates of lipolysis. Also, rates of esterification in the presence of epinephrine correlated positively with the basal rates of esterification, suggesting that stimulated rates of lipolysis and esterification are at least partly determined by the basal rates regardless of nutritional status. The activity of glycerokinase measured in homogenates of isolated fat cells, if applicable to intact fat cells, was sufficient to cause considerable underestimations of the basal rates of lipolysis (using glycerol production as an index). When lipolysis was stimulated, the potential errors of estimating lipolysis by glycerol production alone were negligible.
 ...
PMID:Dependence of rates of lipolysis, esterification, and free fatty acid release in isolated fat cells on age, cell size, and nutritional state. 970 76

The pathways of glycerol-3-P (G3P) generation were examined in retroperitoneal (RETRO) and epididymal (EPI) adipose tissues from rats fed a cafeteria diet for 3 wk. The cafeteria diet induced marked increases in body fat mass and in the plasma levels of insulin and triacylglycerol (TAG). RETRO and EPI from cafeteria diet-fed rats had increased rates of norepinephrine turnover (143 and 60%, respectively) and of de novo fatty acid (FA) synthesis (58 and 98%), compared with controls fed a balanced commercial diet. Cafeteria diet feeding induced marked increases in RETRO and EPI in vivo rates of glucose uptake (52 and 51%, respectively), used to evaluate G3P generation via glycolysis, as well as in glycerokinase activity (119 and 36%) and TAG-glycerol synthesis from glycerol (56 and 71%, respectively). In contrast, there was a marked reduction of glyceroneogenesis in RETRO and EPI from cafeteria diet-fed rats, which was evidenced by the significant decreases of P-enolpyruvate carboxykinase (PEPCK-C) activity (48 and 36%) and TAG-glycerol synthesis from pyruvate (45 and 56%, respectively). Denervation of RETRO from cafeteria diet-fed rats reduced the activity of glycerokinase by 50%, but did not affect glucose uptake or PEPCK-C activity and TAG-glycerol synthesis from pyruvate by the tissue. The data show that glyceroneogenesis can also be inhibited to adjust the supply of G3P to the existing rates of FA esterification and TAG synthesis and suggest that this adjustment is made by reciprocal changes in the generation of G3P from glucose via glycolysis and from glyceroneogenesis, independently from G3P production by glycerokinase.
 ...
PMID:Glyceroneogenesis is reduced and glucose uptake is increased in adipose tissue from cafeteria diet-fed rats independently of tissue sympathetic innervation. 1698 12

Several studies have demonstrated that fish oil consumption improves metabolic syndrome and comorbidities, as insulin resistance, nonalcoholic fatty liver disease, dyslipidaemia and hypertension induced by high-fat diet ingestion. Previously, we demonstrated that administration of a fructose-rich diet to rats induces liver lipid accumulation, accompanied by a decrease in liver cytosolic lipases activities. In this study, the effect of replacement of soybean oil by fish oil in a high-fructose diet (FRUC, 60% fructose) for 8 weeks on lipid metabolism in liver and epididymal adipose tissue from rats was investigated. The interaction between fish oil and FRUC diet increased glucose tolerance and decreased serum levels of triacylglycerol (TAG), VLDL-TAG secretion and lipid droplet volume of hepatocytes. In addition, the fish oil supplementation increased the liver cytosolic lipases activities, independently of the type of carbohydrate ingested. Our results firmly establish the physiological regulation of liver cytosolic lipases to maintain lipid homeostasis in hepatocytes. In epididymal adipose tissue, the replacement of soybean oil by fish oil in FRUC diet did not change the tissue weight and lipoprotein lipase activity; however, there was increased basal and insulin-stimulated de novo lipogenesis and glucose uptake. Increased cytosolic lipases activities were observed, despite the decreased basal and isoproterenol-stimulated glycerol release to the incubation medium. These findings suggest that fish oil increases the glycerokinase activity and glycerol phosphorylation from endogenous TAG hydrolysis. Our findings are the first to show that the fish oil ingestion increases cytosolic lipases activities in liver and adipose tissue from rats treated with high-carbohydrate diets.
 ...
PMID:Replacement of soybean oil by fish oil increases cytosolic lipases activities in liver and adipose tissue from rats fed a high-carbohydrate diets. 2948 86