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

Cinnamon and Brewer's yeast extracts have been shown to potentiate the action of insulin in isolated adipocytes. In this study, isolated rat epididymal adipocytes were used to evaluate the influence of bovine serum albumin on insulin activity as affected by cinnamon and Brewer's yeast extracts. Albumin at 0.01-0.1% decreased the insulin stimulatory effects of cinnamon from 11.8- to 5.3-fold and 2% albumin decreased this effect to near control levels. Conversely, the insulin-enhancing properties of Brewer's yeast remained low in the presence of less than 0.25% albumin but subsequently increased 2.8-, 4.8- and 5.6-fold in the presence of 0.25, 0.50 and 1.0% albumin, respectively. In the absence of added insulin, increased activity of the insulin-stimulated utilization of glucose by both extracts was observed but only Brewer's yeast extract displayed additive effects when tested at higher insulin levels. Due to the inhibitory and enhancing effects of albumin on the insulin activity of cinnamon and Brewer's yeast, respectively, it is suggested that the effects of albumin be assessed when evaluating the insulin-enhancing effects of other substances using isolated adipocytes.
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PMID:Insulin activity: stimulatory effects of cinnamon and brewer's yeast as influenced by albumin. 129 75

The effect of one bout of acute exercise on impaired glucose metabolism was studied in obese (480 +/- 20 g), untrained rats, at rest (n = 10) and after 60 min of swimming (n = 5). Using the euglycemic, hyperinsulinemic (10 mU.kg-1 x min-1) clamp, glucose clearance rate increased from 7.6 +/- 0.9 at rest to 9.7 +/- 0.5 mL.kg-1 x min-1 after exercise (p < 0.05). Glucose (3-O-[14C]methylglucose) transport (GT) into epididymal adipocytes were incubated with or without insulin. In the absence of insulin, GT was 0.13 +/- 0.02 and 0.26 +/- 0.07 fmol.cell-1 x min-1 at rest and after exercise, respectively. In the presence of insulin (25-1000 microU.mL-1) GT increased at rest from 0.97 +/- 0.08 to 1.13 +/- 0.07 fmol.cell-1 x min-1, and after exercise from 1.35 +/- 0.05 to 1.87 +/- 0.11 fmol.cell-1 x min-1. GT was significantly higher after exercise compared with rest (p < 0.004). At rest, maximal insulin effect was achieved at 100 microU.mL-1, whereas with exercise, GT increased gradually with the insulin dosage. The following may be concluded: (i) the biological effect of insulin is amplified in obese rats by one bout of exercise and (ii) exercise affects GT into enlarged adipocytes by enhancing tissue responsiveness to insulin and by a cellular mechanism unrelated to the insulin action.
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PMID:Glucose uptake by adipocytes of obese rats: effect of one bout of acute exercise. 129 60

The effect of chronic hypoxia on the whole-body insulin action in rats was investigated. Rats were kept in a hypobaric hypoxia chamber maintained at a simulated altitude of 4000 m for 10 weeks. At the end of the experimental period, the mean body weight of the hypoxic rats was significantly lower than that of the control rats. The muscle weight to body ratio of the quadriceps muscle in hypoxic rats was larger than that in control rats, but those of the gastrocnemius, soleus, and extensor digitorum longus muscles did not differ between the control and hypoxic rats. On the other hand, the epididymal fat pads of hypoxic rats were markedly smaller than those of the control rats. The results of a euglycemic clamp experiment with infusions of 14 and 3.6 mU insulin.kg-1.min-1 indicated that the steady-state glucose infusion rate was not statistically different between hypoxic and control rats. It is suggested that chronic hypoxia did not influence the whole-body insulin action on glucose transport activity.
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PMID:Effects of chronic hypoxia on the whole-body insulin action in rats. 129 67

The functional interaction of the estrogen-induced uterine enzyme glycerylphosphorylcholine (GPC) diesterase with epididymal rat sperm before and after incubation under capacitating conditions was investigated indirectly, by measuring the glycerol phosphate (GP) released on enzymatic hydrolysis of GPC and using oxygen consumption as a measure of oxidative phosphorylation by the sperm. Freshly released, washed sperm metabolized GP but not GPC. Utilization of GP was found to be inhibited by 2 microM oligomycin but was enhanced dose-dependently in the presence of the uncoupling agent, 2,4-dinitrophenol, indicating that the process was essentially similar to that occurring in somatic mitochondria in that it involved electron transport via ubiquinone and the cytochrome system and was coupled to ATP synthesis. However, on incubation of sperm under conditions supporting capacitation, which led to a striking increase in oxygen consumption, the presence of GP decreased oxygen uptake significantly, in a manner similar to that occurring in the presence of the glycolysable substrate, glucose. The implications of these GPC diesterase-induced metabolic alterations in sperm function are discussed.
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PMID:Glycerylphosphorylcholine (GPC) diesterase related alterations in the oxygen consumption profile of rat spermatozoa in differing functional states. 132 14

An inhibitory effect of fatty acid oxidation on glucose uptake and oxidation has been demonstrated in heart and skeletal muscle under certain experimental conditions. This reciprocal relationship has been termed the glucose-fatty acid cycle. The purpose of the present study was to determine under in vivo conditions whether this interaction was operational in various nonmuscle tissues, and whether infection altered the activity of this cycle. Oral administration of alpha-methylpalmoxirate (MPA; 75 mg/kg), a known inhibitor of long-chain fatty acid oxidation, suppressed hepatic glucose production by 54% and increased whole body glucose disappearance by 15% in nonseptic rats. In contrast, MPA produced a larger reduction of glucose output in septic rats, but did not enhance glucose disposal. In vivo glucose uptake (Rg) by individual tissues was determined using the tracer 2-deoxyglucose technique. In nonseptic animals, MPA increased Rg in "working" muscles (heart and diaphragm; 12-fold and two-fold respectively), but not in "resting" skeletal muscles. MPA increased the Rg of heart and diaphragm to the same level in septic animals. Inhibition of fatty acid oxidation in nonseptic rats also enhanced Rg in liver (174%), spleen (158%), lung (153%), ileum (52%), skin (28%), kidney (115%), and epididymal fat (135%). In septic rats, MPA only increased Rg in the ileum (23%) and kidney (50%). This increased glucose uptake was independent of increases in plasma glucose and insulin concentrations. The infusion of heparin and intralipid, which increased circulating levels of fatty acids, failed to produce consistent changes in either the whole body glucose turnover or glucose uptake by individual tissues. We conclude that under basal in vivo conditions the inhibition of fatty acid oxidation suppresses glucose production and increases peripheral glucose disposal in nonseptic animals. These data support the presence of the glucose-fatty acid cycle in nonmuscle tissues and emphasizes its importance in whole body glucose homeostasis in situations where fatty acid oxidation is impaired. Infection increases glucose uptake by nonmuscle tissues which, for the most part, cannot be further enhanced by the inhibition of lipid oxidation.
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PMID:Regulation of glucose metabolism by free fatty acid availability in septic and nonseptic rats. 142 26

Pioglitazone, a thiazolidinedione, is a novel antidiabetic compound that can lower blood glucose in diabetic rodents by increasing insulin sensitivity in target tissues. We have previously demonstrated that pioglitazone can enhance the insulin- or insulin-like growth factor-1-regulated differentiation of 3T3-L1 cells, a cell line that undergoes morphological and biochemical differentiation to mature adipocytes [Mol. Pharmacol. 41:393-398 (1992)]. In this study, we have examined the effect of pioglitazone on the expression of the adipocyte fatty acid-binding protein (aFABP) in ob/ob mice and 3T3-L1 cells. Administration of the drug to mice was observed to cause a dose-dependent increase in aFABP mRNA expression in epididymal fat, which was correlated with a decrease in blood glucose and insulin levels. Treatment of 3T3-L1 cells with pioglitazone enhanced aFABP expression in a time-dependent fashion. To explore a possible direct effect of pioglitazone on aFABP expression, a chimeric gene was constructed containing the aFABP promoter fused upstream of the bacterial reporter gene for chloramphenicol acetyltransferase. After transfection into 3T3-L1 cells and selection of stable transformants, regulation of the chimeric gene was studied. Pioglitazone, in combination with insulin or insulin-like growth factor-1, was observed to elicit a dose-dependent increase in expression, indicating a role for pioglitazone in regulating transcription of the aFABP gene. Several thiazolidinedione analogs were tested for their ability to induce the expression of the chimeric gene, and it was found that activity in this assay paralleled the structure-activity relationships observed for enhancement of 3T3-L1 cell differentiation. These observations on control of aFABP gene expression by pioglitazone suggest possible mechanisms by which cellular sensitivity to insulin may be regulated.
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PMID:Adipocyte fatty acid-binding protein: regulation of gene expression in vivo and in vitro by an insulin-sensitizing agent. 143 36

Effects of guanine nucleotides on glucose transport were studied in permeabilized rat epididymal fat cells. GTP gamma S and Gpp(NH)p, but not App(NH)p, stimulated 3-O-methylglucose transport. Effect of GTP gamma S was dose-dependent, being detectable at 0.1 mM, and 1.0 mM GTP gamma S stimulated glucose transport to the same extent as insulin. GTP gamma S (0.3 mM) enhanced insulin-stimulated glucose transport while 1 mM GTP gamma S did not affect insulin-mediated transport. GDP beta S had no effect on glucose transport by itself but rather enhanced insulin action. NaF, which is known to activate trimeric G proteins, increased glucose transport to the same extent as insulin. Likewise, mastoparan augmented glucose transport. These results indicate that a certain type of trimeric G protein(s) is involved in the regulation of glucose transport.
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PMID:Stimulation of glucose transport by guanine nucleotides in permeabilized rat adipocytes. 144 5

The metabolic potency of recombinant human insulin-like growth factor II was studied in anaesthetized adult rats by obtaining dose-response curves for the hypoglycaemic action and for the stimulation of glucose metabolism during euglycaemic clamping. Compared to insulin, about 50 times higher doses of insulin-like growth factor II were required to result in identical in vivo responses, with half-maximally effective serum concentrations for the stimulation of glucose disposal during clamp studies of about 0.8 and 50 pmol/ml, respectively. A similar difference in potency was observed for the dose-dependent stimulatory actions on glucose metabolism in individual target tissues. Half-maximally effective serum concentrations in the range of 0.8 to 3.0 pmol/ml for insulin and of 40 to 70 pmol/ml for insulin-like growth factor II were seen to be required for 2-deoxyglucose uptake, glycogen formation in skeletal muscle and lipogenesis in epididymal fat. Maximal responses were identical with both peptides. These data suggest that in vivo acute metabolic actions of insulin-like growth factor II on carbohydrate metabolism occurred through insulin receptors.
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PMID:Acute actions of insulin-like growth factor II on glucose metabolism in adult rats. 145 49

To elucidate the cellular mechanisms for impairment of glucose metabolism associated with aging, the facilitative glucose transporter protein and mRNA were studied in various tissues of young (7-week-old) and aged (20-month-old) rats. GLUT4 glucose transporter protein, a major glucose transporter isoform in the insulin-responsive tissues, was selectively decreased in the epididymal fat tissues of the aged rats compared with the young rats. This decrease is likely to be due to a decrease in protein synthesis rather than in protein stability, since GLUT4 mRNA per unit cellular total RNA was also decreased. GLUT4 mRNA in the skeletal muscle was rather increased in spite of the decreased level of GLUT4 protein in the aged rats, suggesting that the translational efficiency and/or stability of GLUT4 protein is decreased in the skeletal muscle of the aged rats compared with the young rats. In contrast to these alterations in GLUT4 expression, no apparent decrease in the GLUT1 protein amount was observed in the fat tissues, skeletal muscle and brain of the aged rats compared with the young rats. Thus, the tissue and isoform-specific alterations in glucose transporter expression are associated with aging and may contribute to impairment of glucose metabolism observed with aging.
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PMID:Expression of glucose transporter isoforms with aging. 145 71

Rats were fed (for 2 or 6 wk) purified diets containing lard (LD) or menhaden oil (MO) at two levels of dietary fat, i.e., at 11.5 and 20.8% of energy in the low fat (LF) and the medium fat (MF) diets, respectively. Following the diet period, rats were sacrificed after either an overnight fast or after uninterrupted ad libitum feeding. The studies were designed to investigate the dependence of our previously reported effects of MO, i.e. the reduction of plasma free fatty acid (FFA) levels and accumulation of hepatic triacylglycerols, on the dietary fat concentration and the nutritional state of the animal at the time of sacrifice. Reductions in plasma triacylglycerol and cholesterol levels in MO-fed relative to LD-fed rats were observed under all conditions. FFA levels were consistently reduced by MO-feeding at both dietary fat concentrations, but only when blood was sampled from ad libitum fed rats. Under these conditions there was a significant positive relationship between plasma FFA and triacylglycerol concentrations. Reduction in plasma FFA levels may be an additional mechanism associated with the triacylglycerol-lowering effect of fish oil (FO). The LF and MF MO diets caused a rise in plasma glucose levels with no significant change in insulin concentration, indicating that the reduction of FFA by MO was not related to changes in insulin concentration or insulin sensitivity. The MO diets had no effect on skeletal muscle or epididymal adipose tissue lipoprotein lipase activity, demonstrating that catabolism of triacylglycerol-rich lipoproteins contributes little, if any, to the MO-dependent reductions of plasma triacylglycerol and FFA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Reduction in triacylglycerol levels by fish oil correlates with free fatty acid levels in ad libitum fed rats. 148 49


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