The relationship of some rat liver glycolytic enzyme activities to plasma insulin concentration

Abstract Data from a series of experiments demonstrates that maternal supply of polyunsaturated fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), during late gestation affects offspring growth. The increase in growth is independent on the fatty acid supplemented during the growing or finishing phase of the offspring; but it is sex dependent. Dam PUFA supplementation increases wether growth. Supplementation with EPA and DHA to pregnant ewes and to their offspring after weaning showed a treatment interaction in mRNA concentration of hypothalamic neuropeptides associated with dry matter intake (DMI) regulation. A dose increased in EPA and DHA in pregnant ewe diets shows a linear increase in growth, but a quadratic change in DMI or feed efficiency; growth was associated with a linear increase in plasma glucose concentration and a linear decrease in plasma ghrelin concentration. In lambs born from ewes supplemented with different sources of FA during a glucose tolerance test; males’ plasma insulin concentration increased as FA unsaturation degree increased in the dam diet, the opposite happened with females’ plasma insulin concentration. Recent data from our lab showed that the supplementation with EPA and DHA during the last third of gestation to pregnant ewes increased liver and small intestine global DNA methylation and small intestine transporters for amino acids in the fetus. Despite EPA and DHA during late gestation increase growth in the offspring; when EPA and DHA were supplemented in early gestation, offspring growth was lesser that lambs born from ewes supplemented a saturated and monounsaturated lipid. The reason for the difference in results it is not clear. However, more studies focusing in some aspect of the biology will help to understand what specific fatty acid needs to be supplemented at different stages of gestation to improve offspring growth.

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Fetal growth, glucose tolerance and plasma insulin concentration in rats given a marginal-zinc diet in the latter stages of pregnancy

British Journal Of Nutrition ◽

10.1079/bjn19880038 ◽

1988 ◽

Vol 59 (2) ◽

pp. 315-322 ◽

Cited By ~ 5

Author(s):

Susan Southon ◽

Susan J. Fairweather-Tait ◽

Christine M. Williams

Keyword(s):

Blood Glucose ◽

Glucose Concentration ◽

Plasma Insulin ◽

Insulin Concentration ◽

Oral Glucose ◽

Fetal Blood ◽

Plasma Insulin Concentration ◽

Pregnant Rats ◽

Zn Content ◽

Tail Blood

1. Wistar rats were fed on a control semi-synthetic diet throughout pregnancy, or a control diet in the first 2 weeks and a marginal-zinc diet in the 3rd week of pregnancy. On day 20, after an overnight fast, half the animals in each group were given glucose by gavage and the 0–30 min rise in blood glucose measured in tail blood. After 60 min blood was taken by cardiac puncture for glucose and insulin assay. Maternal pancreases were removed and the Zn contents measured. Fetuses from each litter were combined for wet/dry weights, protein and DNA determinations.2. Plasma insulin concentration was higher, and glucose concentration and pancreatic Zn content lower, in pregnantv. non-pregnant animals of similar age, fed on the same diet. Pancreatic Zn content was lowest in the marginal-Zn group of pregnant rats. Fetuses from mothers fed on the marginal-Zn diet during the last week of pregnancy were slightly heavier than controls and had a significantly higher protein: DNA ratio. The 0–30 min rise in blood glucose was significantly greater in the marginal-Zn animals.3. In a second experiment, pregnant rats were given similar diets to those used in the first study, but the marginal-Zn diet was given for a shorter period (days 15–19 of pregnancy). On day 19 the rats were meal-fed and on day 20, after an overnight fast, an oral glucose dose was administered. Tail-blood was taken at timed intervals up to 60 min post-dosing for glucose assay. Both maternal and fetal blood glucose and insulin concentration was measured 70 min post-dosing.4. Values for maternal and fetal blood glucose and plasma insulin, measured 70 min after the administration of a glucose dose, were similar in the two groups, but the initial rise in blood glucose concentration was again significantly higher in pregnant rats given the marginal-Zn diet towards term.5. It is suggested that the change in growth and composition, observed in fetuses from rats given a marginal-Zn diet in later pregnancy, is associated with altered maternal carbohydrate metabolism.

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The effect of acetoacetate on plasma insulin concentration

Biochemical Journal ◽

10.1042/bj1250541 ◽

1971 ◽

Vol 125 (2) ◽

pp. 541-544 ◽

Cited By ~ 31

Author(s):

R. A. Hawkins ◽

K. G. M. M. Alberti ◽

C. R. S. Houghton ◽

D. H. Williamson ◽

H. A. Krebs

Keyword(s):

Fatty Acids ◽

Blood Glucose ◽

Free Fatty Acids ◽

Glucose Concentration ◽

Plasma Insulin ◽

Blood Glucose Concentration ◽

Diabetic Rats ◽

Insulin Concentration ◽

Plasma Insulin Concentration ◽

Arterial Blood

1. Sodium acetoacetate was infused into the inferior vena cava of fed rats, 48h-starved rats, and fed streptozotocin-diabetic rats treated with insulin. Arterial blood was obtained from a femoral artery catheter. 2. Acetoacetate infusion caused a fall in blood glucose concentration in fed rats from 6.16 to 5.11mm in 1h, whereas no change occurred in starved or fed–diabetic rats. 3. Plasma free fatty acids decreased within 10min, from 0.82 to 0.64mequiv./l in fed rats, 1.16 to 0.79mequiv./l in starved rats and 0.83 to 0.65mequiv./l in fed–diabetic rats. 4. At 10min the plasma concentration rose from 20 to 49.9μunits/ml in fed unanaesthetized rats and from 6.4 to 18.5μunits/ml in starved rats. There was no change in insulin concentration in the diabetic rats. 5. Nembutal-anaesthetized fed rats had a more marked increase in plasma insulin concentration, from 30 to 101μunits/ml within 10min. 6. A fall in blood glucose concentration in fed rats and a decrease in free fatty acids in both fed and starved rats is to be expected as a consequence of the increase in plasma insulin. 7. The fall in the concentration of free fatty acids in diabetic rats may be due to a direct effect of ketone bodies on adipose tissue. A similar effect on free fatty acids could also be operative in normal fed or starved rats.

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Adrenergic blockade prevents endotoxin-induced increases in glucose metabolism

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1988.255.5.e629 ◽

1988 ◽

Vol 255 (5) ◽

pp. E629-E635 ◽

Cited By ~ 1

Author(s):

D. M. Hargrove ◽

G. J. Bagby ◽

C. H. Lang ◽

J. J. Spitzer

Keyword(s):

Plasma Insulin ◽

Lactate Concentration ◽

Insulin Concentration ◽

Adrenergic Blockade ◽

Plasma Lactate ◽

Glucose Kinetics ◽

Plasma Insulin Concentration ◽

Beta Adrenergic ◽

Plasma Lactate Concentration ◽

Adrenergic Antagonists

Combined alpha- and beta-adrenergic blockade was used to investigate the role of catecholamines in endotoxin-induced elevations in glucose kinetics. Glucose kinetics were measured before and for 4 h after the injection of endotoxin [100 micrograms/100 g body wt iv, 30% lethal dose (LD30) at 24 h]. Adrenergic blockade was achieved by the bolus injection of phentolamine and propranolol followed by their continuous infusion. Endotoxin-treated rats exhibited a transient hyperglycemia and sustained (greater than 4 h) increase in plasma lactate concentration, as well as elevated rates of glucose appearance (Ra, 83%), disappearance (Rd, 58%), recycling (160%), and metabolic clearance (23%). Adrenergic blockade prevented endotoxin-induced increases in plasma glucose concentration, Ra, Rd, and recycling but not glucose clearance. The increase in plasma lactate concentration was blunted by 35%. After 2 h, endotoxic animals infused with adrenergic antagonists developed hypoglycemia, which may have resulted from an increased plasma insulin concentration. The attenuation of elevated glucose turnover by adrenergic blockade in the endotoxin-treated animals was not due to a reduction in plasma glucagon level or differences in plasma insulin concentration. Administration of the alpha- or beta-adrenergic antagonists separately blunted but did not prevent endotoxin-induced changes in glucose kinetics, and therefore the efficacy of the adrenergic blockade could not be assigned to a single receptor class. These results indicate that catecholamines are important contributory factors to many of the early alterations in carbohydrate metabolism observed during endotoxemia.

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EFFECT OF DECAPITATION ON THE DEVELOPMENT OF INSULIN SECRETION IN THE FOETAL RABBIT

Journal of Endocrinology ◽

10.1677/joe.0.0570023 ◽

1973 ◽

Vol 57 (1) ◽

pp. 23-31 ◽

Cited By ~ 10

Author(s):

P. M. B. JACK ◽

R. D. G. MILNER

Keyword(s):

Insulin Secretion ◽

Plasma Insulin ◽

Insulin Concentration ◽

Β Cell ◽

Plasma Insulin Concentration ◽

Intrauterine Development ◽

Foetal Head ◽

Significant Difference ◽

The Mean ◽

Control Litter

SUMMARY One rabbit foetus in a litter was decapitated on day 24 of gestation. On day 29 the litter was killed and blood was collected from all foetuses for the measurement of plasma insulin concentration. The pancreas of the decapitated foetus and that of the control litter-mate with the nearest headless body weight were cut into pieces and incubated in a physiological buffer containing 0·6 or 3·0 mg glucose/ml. The pancreas of the decapitated foetus secreted significantly more insulin than that of the control foetus in either concentration of glucose in the medium. Higher insulin secretion from the decapitated foetus persisted for 4·5 h of incubation and was demonstrable in both the first 5 and subsequent 25 min of incubation when the pancreas was initially transferred to incubation medium containing 3·0 mg glucose/ml. The mean plasma insulin concentration of the foetuses decapitated on day 24 was higher on day 29 than that of the control foetuses but there was no significant difference between the concentration of insulin in the pancreas of the two groups of animals. The results indicate that removal of the foetal head influences the intrauterine development of the rabbit β-cell.

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Substrate metabolism when subjects are fed carbohydrate during exercise

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1999.276.5.e828 ◽

1999 ◽

Vol 276 (5) ◽

pp. E828-E835 ◽

Cited By ~ 13

Author(s):

Jeffrey F. Horowitz ◽

Ricardo Mora-Rodriguez ◽

Lauri O. Byerley ◽

Edward F. Coyle

Keyword(s):

Plasma Insulin ◽

Fat Oxidation ◽

Insulin Concentration ◽

Peak Oxygen Consumption ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Plasma Insulin Concentration ◽

Carbohydrate Ingestion ◽

Low Intensity ◽

Low Intensity Exercise

This study determined the effect of carbohydrate ingestion during exercise on the lipolytic rate, glucose disappearance from plasma (Rd Glc), and fat oxidation. Six moderately trained men cycled for 2 h on four separate occasions. During two trials, they were fed a high-glycemic carbohydrate meal during exercise at 30 min (0.8 g/kg), 60 min (0.4 g/kg), and 90 min (0.4 g/kg); once during low-intensity exercise [25% peak oxygen consumption (V˙o 2 peak)] and once during moderate-intensity exercise (68%V˙o 2 peak). During two additional trials, the subjects remained fasted (12–14 h) throughout exercise at each intensity. After 55 min of low-intensity exercise in fed subjects, hyperglycemia (30% increase) and a threefold elevation in plasma insulin concentration ( P < 0.05) were associated with a 22% suppression of lipolysis compared with when subjects were fasted (5.2 ± 0.5 vs. 6.7 ± 1.2 μmol ⋅ kg−1 ⋅ min−1, P < 0.05), but fat oxidation was not different from fasted levels at this time. Fat oxidation when subjects were fed carbohydrate was not reduced below fasting levels until 80–90 min of exercise, and lipolysis was in excess of fat oxidation at this time. The reduction in fat oxidation corresponded in time with the increase in Rd Glc. During moderate-intensity exercise, the very small elevation in plasma insulin concentration (∼3 μU/ml; P < 0.05) during the second hour of exercise when subjects were fed vs. when they were fasted slightly attenuated lipolysis ( P < 0.05) but did not increase Rd Glc or suppress fat oxidation. These findings indicate that despite a suppression of lipolysis after carbohydrate ingestion during exercise, the lipolytic rate remained in excess and thus did not limit fat oxidation. Under these conditions, a reduction in fat oxidation was associated in time with an increase in glucose uptake.

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Solubilization and partial purification of particulate catechol-O-methyltransferase from rat liver

Canadian Journal of Biochemistry ◽

10.1139/o77-164 ◽

1977 ◽

Vol 55 (10) ◽

pp. 1108-1113 ◽

Cited By ~ 41

Author(s):

J. H. Tong ◽

A. D'Iorio

Keyword(s):

Rat Liver ◽

Partial Purification ◽

Catecholamine Metabolism ◽

Ph Profile ◽

Significant Difference ◽

Solubilized Enzyme ◽

Relationship Of ◽

The Relationship ◽

Substrate Affinities

Particulate catechol-O-methyltransferase (COMT) from rat liver has been solubilized by acetone treatment and partially purified. Results from the present study demonstrate that the solubilized, partially purified enzyme is similar to the cytosol COMT with respect to molecular weight, pH profile, sensitivity toward inhibitors, Mg2+ requirement, and substrate affinities. However, a comparison of the crude particulate COMT and the solubilized enzyme shows that there is a significant difference in their affinity for catechol substrates. This finding suggests that membrane protein and (or) lipid components may play an important role in catecholamine metabolism. The relationship of particulate COMT to [3H]norepinephrine binding was investigated. No correlation between the COMT and [3H]norepinephrine binding activities was observed in vitro.

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