scholarly journals Effects of exogenous insulin or vanadate on disposal of dietary triacylglycerols between mammary gland and adipose tissue in the lactating rat: insulin resistance in white adipose tissue

1993 ◽  
Vol 290 (2) ◽  
pp. 557-561 ◽  
Author(s):  
T H M Da Costa ◽  
D H Williamson
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipase Activity ◽  
Dietary Lipid ◽  
Lipid Deposition ◽  
Exogenous Insulin ◽  
Lipoprotein Lipase Activity ◽  
Stimulation Of

The effects of exogenous insulin or vanadate (an insulin mimetic) on the disposal of dietary [14C]lipid between oxidation to 14CO2, deposition in adipose tissue or uptake by mammary gland and transfer to suckling pups were studied in virgin and lactating rats. After an oral load of [1-14C]triolein, virgin rats treated with a supraphysiological dose of insulin over 24 h showed a decrease (58%) in 14CO2 production and increased accumulation of [14C]lipid in carcass and white adipose tissue. There was a 2.5-fold increase in lipoprotein lipase activity in the latter. Chronic vanadate administration (12 days) had no effect on these parameters. In lactating rats, the stimulation of the deposition of [14C]lipid in adipose tissue by exogenous insulin was about 10% of that in virgin rats. In prolactin-deficient lactating rats there was no stimulation of [14C]lipid deposition in adipose tissue by insulin. However, both insulin and vanadate treatment increased the accumulation of [14C]lipid in mammary gland to the values seen in the mammary glands plus pups of normal lactating rats. Lipoprotein lipase activity in the gland was also restored to normal values. It is concluded that in lactation there is resistance to insulin stimulation of dietary lipid deposition in adipose tissue, and that this is not due to circulating prolactin. In addition, exogenous insulin plays a role in the regulation of lipoprotein lipase and hence of dietary lipid uptake into lactating mammary gland.

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 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 A High Dietary Lipid Intake during Pregnancy and Lactation Enhances Mammary Gland Lipid Uptake and Lipoprotein Lipase Activity in Rats

1999 ◽  
Vol 129 (8) ◽  
pp. 1574-1578 ◽  
Author(s):  
Martha Del Prado ◽  
Salvador Villalpando ◽  
Joaquín Gordillo ◽  
Homero Hernández-Montes
Keyword(s):  
Mammary Gland ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Dietary Lipid ◽  
Lipid Uptake ◽  
Lipoprotein Lipase Activity ◽  
Pregnancy And Lactation

scholarly journals Changes in the lipoprotein lipase (clearing-factor lipase) activity of white adipose tissue during development of the rat

1978 ◽  
Vol 172 (2) ◽  
pp. 319-325 ◽  
Author(s):  
A Cryer ◽  
H M Jones
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipase Activity ◽  
Plasma Insulin ◽  
Serum Concentrations ◽  
Lipoprotein Lipase Activity ◽  
Activity Change ◽  
Adipose Tissue Lipoprotein Lipase

The lipoprotein lipase (clearing-factor lipase) activity of the white adipose tissue from rats aged between 1 and 145 days was determined. Five adipose-tissue sites (epididymal, uterine, subcutaneous, perirenal and intramuscular) together with serum concentrations of triacylglycerol, cholesterol and glucose were studied. The pattern of enzyme-activity change was remarkably similar in all the sites studied, although the growth of the tissues proceeded non-uniformly. After a peak of activity early in suckling, lipoprotein lipase activity fell to low values by 20 days of age. At weaning (21 days) the activity increased sharply and within 5 days high values were regained. The serum triacylglycerol and cholesterol concentrations were low at birth and reached peaks of concentration coincidentally with the minima of white-adipose-tissue lipoprotein lipase activities, seen late in suckling. The changes in enzyme activity were related to other metabolic changes in adipose tissue and with the known changes in plasma insulin concentrations occurring during development.

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