scholarly journals Tissue-specific effects of starvation and refeeding on the disposal of oral [1-14C]triolein in the rat during lactation and on removal of litter

1988 ◽  
Vol 254 (2) ◽  
pp. 539-546 ◽  
Author(s):  
C M Oller do Nascimento ◽  
D H Williamson
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Brown Adipose Tissue ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipid Accumulation ◽  
Milk Lipid ◽  
Plasma Insulin Concentration ◽  
Brown Adipose ◽  
14Co2 Production

1. The effects of starvation and refeeding on the disposal of oral [14C]triolein between 14CO2 production and 14C-lipid accumulation in tissues of virgin rats, lactating rats and lactating rats with pups removed were studied. 2. Starvation (24 h) increased 14CO2 production in lactating rats and lactating rats with pups removed to values found in virgin rats. This increase was accompanied by decreases in 14C-lipid accumulation in mammary gland and pups of lactating rats and in white and brown adipose tissue of lactating rats with pups removed. 3. Short-term (2 h) refeeding ad libitum decreased 14CO2 production in lactating rats and lactating rats with pups removed, and restored the 14C-lipid accumulation in mammary glands plus pups and in white and brown adipose tissue respectively 4. Insulin deficiency induced with mannoheptulose inhibited the restoration of 14C-lipid accumulation in white adipose tissue on refeeding of lactating rats with pups removed, but did not prevent the restoration of 14C-lipid accumulation in mammary gland. 5. Changes in the activity of lipoprotein lipase in mammary gland and white adipose tissue paralleled the changes in 14C-lipid accumulation in these tissues. 6. It is concluded that 14C-lipid accumulation in mammary gland may not be affected by changes in plasma insulin concentration and that it is less sensitive to starvation than is lipogenesis or lactose synthesis. This has the advantage that the milk lipid content can still be maintained from hepatic very-low-density lipoprotein for a period after withdrawal of food. The major determinant of the disposal of oral 14C-triolein appears to be the total tissue activity of lipoprotein lipase. When this is high in mammary gland (fed lactating rats) or white adipose tissue (fed lactating rats with pups removed), less triacylglycerol is available for the muscle mass and consequently less is oxidized.

scholarly journals Lipid metabolism in the obese Zucker rat. Disposal of an oral [14C]triolein load and lipoprotein lipase activity

1991 ◽  
Vol 274 (3) ◽  
pp. 651-656 ◽  
Author(s):  
E J López-Soriano ◽  
N Carbó ◽  
J M Argilés
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipase Activity ◽  
Lipid Accumulation ◽  
Zucker Rats ◽  
Lipoprotein Lipase Activity ◽  
Brown Adipose ◽  
Obese Rats

Oxidation in vivo of [14C]triolein to 14CO2 was significantly lower in obese (fa/fa) Zucker rats as compared with their lean (+/?) controls. In response to a 24 h starvation period, both lean and obese rats showed an enhanced rate of [14C]triolein oxidation. There were, however, no changes in the rate of intestinal absorption of [14C]triolein between the lean and obese animals. Conversely, the total tissular [14C]lipid accumulation was significantly higher in white adipose tissue, carcass and plasma in the obese animals, whereas that of brown adipose tissue was lower. This was associated with a marked hyperinsulinaemia and hypertriglyceridaemia in the fa/fa animals. Starvation dramatically decreased [14C]lipid accumulation in white adipose tissue of the lean Zucker rats, but had no effect in the obese rats. The lipogenic rate of the obese rats was significantly higher than that of lean rats in liver, white adipose tissue, skeletal muscle and carcass. Lipoprotein lipase activity (per g of tissue) was significantly lower in both white and brown adipose tissue of obese versus lean rats; however, total activity was higher in both tissues. Starvation significantly lowered perigenital-adipose-tissue lipoprotein lipase activity in the lean groups, and had no effect in the obese ones. These results demonstrate that the tissue capacity of exogenous lipid uptake is involved, but cannot be the only factor influencing the maintenance of obesity in these animals. Thus, in the adult fa/fa rat, the large increase in obesity is not solely dependent on a deviation of energy-producing substrate metabolism towards the storage of lipids in white fat. Other factors, such as a low rate of oxidation, a high lipogenic rate and decreased brown-adipose-tissue activity are involved in the perseverance of the obesity syndrome.

scholarly journals Re-examination of the putative roles of insulin and prolactin in the regulation of lipid deposition and lipogenesis in vivo in mammary gland and white and brown adipose tissue of lactating rats and litter-removed rats

1989 ◽  
Vol 258 (1) ◽  
pp. 273-278 ◽  
Author(s):  
C M Oller do Nascimento ◽  
V Ilic ◽  
D H Williamson
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Brown Adipose Tissue ◽  
White Adipose Tissue ◽  
Lipid Accumulation ◽  
Plasma Insulin ◽  
Fold Increase ◽  
Plasma Prolactin ◽  
Brown Adipose

1. The effects of various treatments to alter either plasma prolactin (bromocryptine administration or removal of litter) or the metabolic activity of the mammary gland (unilateral or complete teat sealing) on the disposal of oral [14C]lipid between 14CO2 production and [14C]lipid accumulation in tissues of lactating rats were studied. In addition, the rates of lipogenesis in vivo were measured in mammary gland, brown and white adipose tissue and liver. 2. Bromocryptine administration lowered plasma prolactin, but did not alter [14C]lipid accumulation in mammary gland or in white and brown adipose tissue. 3. In contrast, complete sealing of teats results in no change in plasma prolactin, but a 90% decrease in [14C]lipid accumulation in mammary gland and a 4-fold increase in white and brown adipose tissue. The rate of lipogenesis in mammary gland was decreased by 95%, but there was no change in the rate in white and brown adipose tissue. Unilateral sealing of teats resulted in a decrease in [14C]lipid accumulation in white adipose tissue. 4. Removal of the litter for 24 h (low prolactin) produced a similar pattern to complete teat sealing, except that there was a 6-fold increase in lipogenesis in white adipose tissue. Re-suckling for 5 h increased plasma prolactin, but did not alter the response seen in litter-removed lactating rats. 5. Changes in lipoprotein lipase activity and in plasma insulin paralleled the reciprocal changes in [14C]lipid accumulation in white and brown adipose tissue and in mammary gland. 6. It is concluded that the plasma insulin is more important than prolactin in regulating lipid deposition in adipose tissue during lactation, and that any effects of prolactin must be indirect.

scholarly journals Effects of tri-iodothyronine administration on the disposal of oral [1-14C]triolein, lipoprotein lipase activity and lipogenesis in the rat during lactation and on removal of the litter

1994 ◽  
Vol 301 (2) ◽  
pp. 495-501 ◽  
Author(s):  
M Del Prado ◽  
T H Da Costa ◽  
D H Williamson
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Mammary Gland ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipase Activity ◽  
Plasma Prolactin ◽  
Lipoprotein Lipase Activity ◽  
14Co2 Production ◽  
Pup Growth

The effect of tri-iodothyronine (T3) administration on the utilization of dietary [14C]lipid by the mammary gland and adipose tissue of lactating and litter-removed rats was studied. (1) After an oral load of [1-14C]triolein, the lactating rats treated with T3 (50 micrograms/100 g body wt.) over 24 h showed an increase in 14CO2 production and a decrease in the total [14C]lipid transferred through the mammary gland that was paralleled by a decrease in tissue lipoprotein lipase (LPL) activity. (2) T3 administration decreased plasma prolactin in the lactating rats. Prolactin replacement in T3-treated rats restored LPL activity in the mammary gland, but did not increase the amount of dietary [14C]lipid transferred to the milk. (3) Chronic T3 administration (4 days) to lactating rats did not affect pup growth or the lipogenic rate in the mammary gland. (4) The administration of T3 to litter-removed rats inhibited the increase of LPL activity in white adipose tissue and decreased the accumulation of dietary [14C]lipid. This decrease was accompanied by increased 14CO2 production and [14C]lipid accumulation in skeletal muscle and heart. (5) It is concluded that hyperthyroidism depresses LPL activity in mammary gland and white adipose tissue, but not in muscle. The increased accumulation of [14C]lipid in muscle and increased production of 14CO2 in lactating and in litter-removed rats treated with T3 is in part due to the decreased total LPL in mammary gland and adipose tissue respectively, which are therefore less able to compete with muscle for the available plasma triacylglycerols.

scholarly journals Immunochemical studies with soluble and mitochondrial pyruvate carboxylase activities from rat tissues

1970 ◽  
Vol 119 (4) ◽  
pp. 735-742 ◽  
Author(s):  
F. J. Ballard ◽  
R. W. Hanson ◽  
Lea Reshef
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Brown Adipose Tissue ◽  
Rat Liver ◽  
White Adipose Tissue ◽  
Pyruvate Carboxylase ◽  
Specific Activity ◽  
Rat Liver Mitochondria ◽  
Rat Tissues ◽  
Brown Adipose

1. Pyruvate carboxylase (EC 6.4.1.1), purified from rat liver mitochondria to a specific activity of 14 units/mg, was used for the preparation of antibodies in rabbits. 2. Tissue distribution studies showed that pyruvate carboxylase was present in all rat tissues that were tested, with considerable activities both in gluconeogenic tissues such as liver and kidney and in tissues with high rates of lipogenesis such as white adipose tissue, brown adipose tissue, adrenal gland and lactating mammary gland. 3. Immunochemical titration experiments with the specific antibodies showed no differences between the inactivation of pyruvate carboxylase from mitochondrial or soluble fractions of liver, kidney, mammary gland, brown adipose tissue or white adipose tissue. 4. The antibodies were relatively less effective in reactions against pyruvate carboxylase from sheep liver than against the enzyme from rat tissues. 5. Pyruvate carboxylase antibodies did not inactivate either propionyl-CoA carboxylase or acetyl-CoA carboxylase from rat liver. 6. It is concluded that pyruvate carboxylase in lipogenic tissues is similar antigenically to the enzyme in gluconeogenic tissues and that the soluble activities of pyruvate carboxylase detected in many rat tissues do not represent discrete enzymes but are the result of mitochondrial damage during tissue homogenization.

scholarly journals Tissue-specific effects of rapid tumour growth on lipid metabolism in the rat during lactation and on litter removal

1988 ◽  
Vol 252 (1) ◽  
pp. 65-72 ◽  
Author(s):  
R D Evans ◽  
D H Williamson
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Lipid Metabolism ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipase Activity ◽  
Lipid Accumulation ◽  
Lipoprotein Lipase Activity ◽  
Tumour Burden ◽  
Plasma Triacylglycerol

1. The effect of tumour burden on lipid metabolism was examined in virgin, lactating and litter-removed rats. 2. No differences in food intake or plasma insulin concentrations were observed between control animals and those bearing the Walker-256 carcinoma (3-5% of body wt.) in any group studied. 3. In virgin tumour-bearing animals, there was a significant increase in liver mass, blood glucose and lactate, and plasma triacylglycerol; the rate of oxidation of oral [14C]lipid to 14CO2 was diminished, and parametrial white adipose tissue accumulated less [14C]lipid compared with pair-fed controls. 4. These findings were accompanied by increased accumulation of lipid in plasma and decreased white-adipose-tissue lipoprotein lipase activity. 5. In lactating animals, tumour burden had little effect on the accompanying hyperphagia or on pup weight gain; tissue lipogenesis was unaffected, as was tissue [14C]lipid accumulation, plasma [triacylglycerol] and white-adipose-tissue and mammary-gland lipoprotein lipase activity. 6. On removal (24 h) of the litter, the presence of the tumour resulted in decreased rates of lipogenesis in the carcass, liver and white and brown adipose tissue, decreased [14C]lipid accumulation in white adipose tissue, but increased accumulation in plasma and liver, increased plasma [triacylglycerol] and decreased lipoprotein lipase activity in white adipose tissue. 7. The rate of triacylglycerol/fatty acid substrate cycling was significantly decreased in white adipose tissue of virgin and litter-removed rats bearing the tumour, but not in lactating animals. 8. These results demonstrate no functional impairment of lactation, despite the presence of tumour, and the relative resistance of the lactating mammary gland to the disturbance of lipid metabolism that occurs in white adipose tissue of non-lactating rats with tumour burden.

scholarly journals Evidence for conservation of dietary lipid in the rat during lactation and the immediate period after removal of the litter. Decreased oxidation of oral [1-14C]triolein

1986 ◽  
Vol 239 (1) ◽  
pp. 233-236 ◽  
Author(s):  
C M Oller do Nascimento ◽  
D H Williamson
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Lipoprotein Lipase ◽  
Relative Activity ◽  
Dietary Lipid ◽  
Litter Removal ◽  
Lactating Mammary Gland ◽  
14Co2 Production

Production of 14CO2 from an oral load of [1-14C]triolein was greatly decreased (70%) in lactating rats or immediately after (24-48 h) removal of the litter, compared with virgin rats. This decreased oxidation of dietary lipid was accompanied by accumulation of 14C-labelled lipid in lactating mammary gland or adipose tissue (after litter removal). No difference in 14CO2 production between lactating and virgin rats was observed when [1-14C]octanoate was administered. It is concluded that a major factor in this conservation of dietary triacylglycerol is the relative activity of lipoprotein lipase in the tissues.

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