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

Prado, Martha Del; Costa, Teresa Helena Macedo da; Williamson, Dermot H.

doi:10.1042/bj3010495

Cited by 6 publications

(3 citation statements)

References 45 publications

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“…Similar conclusions may be attained when analyzing the data found at midlactation in the litter removed rat. In agreement with previous reports, 30,39 LPL activity greatly declined in the mammary gland, whereas it increased in lumbar adipose tissue. Plasma triglyceride levels greatly increased in these animals.…”

Section: Discussionsupporting

confidence: 93%

“…[27][28][29] Therefore, the present study was undertaken to determine the potential relationship between changes in LPL activity in adipose tissue and the mammary gland as compared with their content of ␣-tocopherol during late gestation and midlactation in the rat. Because litter separation at midlactation causes an abrupt and opposite change in LPL activity in the mammary gland and adipose tissue, [30][31][32] this strategy was also used to determine its effect on ␣-tocopherol content in these tissues. Results show that around parturition and during lactation in the rat, changes in ␣-tocopherol content in the mammary gland correlate with tissue LPL activity, suggesting a direct relationship, whereas this is not the case in adipose tissue, where major changes in LPL activity are not followed by parallel changes in its content of ␣-tocopherol.…”

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confidence: 99%

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Uptake of [alpha ]-tocopherol by the mammary gland but not by white adipose tissue is dependent on lipoprotein lipase activity around parturition and during lactation in the rat

2002

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This study was undertaken to test the potential role of changes in lipoprotein lipase (LPL) activity in the mammary gland and adipose tissue around parturition and lactation on the uptake of alpha-tocopherol in the rat. Plasma levels of alpha-tocopherol and triglycerides were higher in 20-day pregnant rats than in virgin rats, whereas its concentration was higher in the mammary gland of the former, and no differences were detected in adipose tissue between the groups. After an oral alpha-tocopherol and triglyceride load, both appeared in plasma faster in pregnant rats than in virgin rats, the change being even faster for alpha-tocopherol than for triglycerides. After 24 hours, both alpha-tocopherol and triglycerides in d < 1.006 lipoproteins were higher in pregnant rats than in virgin rats, LPL activity was higher in the mammary gland, and lower in adipose tissue in the former, whereas alpha-tocopherol concentration also appeared higher in the mammary gland of pregnant rats, and no differences were detected between the groups in adipose tissue. At day 13 of lactation, an oral load of alpha-tocopherol and triglycerides caused a higher increase of plasma alpha-tocopherol levels than triglycerides, and this effect decreased when rats had their litter removed 48 hours before analysis. In these litter-removed rats, the appearance of alpha-tocopherol and triglycerides in plasma was higher in d < 1.006 lipoproteins than in lactating rats. Also, both LPL activity and alpha-tocopherol concentration in the mammary gland plus milk was lower in litter-removed rats than in the lactating rats, whereas LPL in adipose tissue was higher in the former, although no difference in alpha-tocopherol was found. Thus, data are consistent with the role of LPL activity in the mammary gland modulating the uptake of alpha-tocopherol during pregnancy and lactation, although this is not true in adipose tissue.

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Section: Discussionsupporting

confidence: 93%

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confidence: 99%

Uptake of [alpha ]-tocopherol by the mammary gland but not by white adipose tissue is dependent on lipoprotein lipase activity around parturition and during lactation in the rat

2002

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“…This is consistent with the linear relationship that has been reported between TG secretion rate and plasma TG concentration, after presumed blockade of peripheral TG clearance by Triton WR1339, in rats with increasing concentrations of plasma L-T4 [22]. Additionally, it has been shown that the administration of 50 ig/100 g body weight of 14 causes diminution of lipoprotein lipase activity in both mammary gland and adipose tissue [23]. A decreased activity of lipoprotein Iipase in peripheral tissues also could contribute to the higher levels of triglyceride in serum of chronic hyperthyroid rats.…”

Section: Discussionsupporting

confidence: 90%

Lipids in Rat Liver Submitted to Acute and Chronic Hyperthyroidism

Varas¹,

Oliveros²,

Giménez³

1999

Horm Metab Res

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The effect of acute and chronic hyperthyroidism was studied in serum and liver lipids in rats. Wistar adult female rats were separated into three groups. The first group, injected with saline solution was used as control (Co), while the second and third were injected daily with tetraiodothyronine (T4) 10 microg/100 g body weight; the second group (HT-I) for one week and the third group (HT-II) for five weeks. In HT-I, serum T4 level was higher than in HT-II. Triiodothyronine (T3) concentration increased in HT-I and HT-II. The serum triglyceride concentration increased in HT-II in relation to HT-I and Co groups. Serum total cholesterol, HDL-cholesterol and bile acids did not vary among the three groups. LDL cholesterol fraction was lower in HT-I and HT-II than in Co group. In the liver, total and free cholesterol (FC) concentrations decreased in HT-I, but both increased in HT-II, in relation to Co. Esterified cholesterol did not change among the three groups. Liver triglyceride (TG) mass decreased in HT-I and HT-II in relation to Co, but it was higher in HT-II than in HT-I. Hepatic fatty-acid synthase (FAS) and acetyl-CoA carboxylase (ACC) activities increased in HT-I and HT-II in relation to Co and there were no differences between HT-I and HT-II. The incorporation of [3H]-H2O into esterified cholesterol did not differ significantly among the groups, while its incorporation into FC decreased and into TG increased in HT-I and HT-II, in relation to Co. The effect of T4 on the amount and turnover of lipids is affected by the time of hormone administration, but the increase of FAS and ACC activities was the same for both times studied.

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Hyperthyroidism affects lipid metabolism in lactating and suckling rats

Varas

Jahn

Giménez

2001

Lipids

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Two per thousand pregnant women have hyperthyroidism (HT), and although the symptoms are attenuated during pregnancy, they rebound after delivery, affecting infant development. To examine the effects of hyperthyroidism on lactation, we studied lipid metabolism in maternal mammary glands and livers of hyperthyroid rats and their pups. Thyroxine (10 microg/100 g body weight/d) or vehicle-treated rats were made pregnant 2 wk after commencement of treatment and sacrificed on days 7, 14, and 21 of lactation with the litters. Circulating triiodothyronine and tetraiodothyronine concentrations in the HT mothers were increased on all days. Hepatic esterified cholesterol (EC) and free cholesterol (FC) and triglyceride (TG) concentrations were diminished on days 14 and 21. Lipid synthesis, measured by incorporation of [3H]H2O into EC, FC, and TG, fatty acid synthase, and acetyl CoA carboxylase activities increased at day 14, while incorporation into FC and EC decreased at days 7 and 21, respectively. Mammary FC and TG concentrations were diminished at day 14; incorporation of [3H]H2O into TG decreased at days 7 and 21, and incorporation of [3H]H2O into FC increased at day 14. In the HT pups, growth rate was diminished, tetraiodothyronine concentration rose at days 7 and 14 of lactation, and triiodothyronine increased only at day 14. Liver TG concentrations increased at day 7 and fell at day 14, while FC increased at day 14 and only acetyl CoA carboxylase activity fell at day 14. Thus, hyperthyroidism changed maternal liver and mammary lipid metabolism, with decreased lipid concentration in spite of increased liver rate of synthesis and decreases in mammary synthesis. These changes, along with the mild hyperthyroidism of the litters, may have contributed to their reduced growth rate.

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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

Cited by 6 publications

References 45 publications

Uptake of [alpha ]-tocopherol by the mammary gland but not by white adipose tissue is dependent on lipoprotein lipase activity around parturition and during lactation in the rat

Uptake of [alpha ]-tocopherol by the mammary gland but not by white adipose tissue is dependent on lipoprotein lipase activity around parturition and during lactation in the rat

Lipids in Rat Liver Submitted to Acute and Chronic Hyperthyroidism

Hyperthyroidism affects lipid metabolism in lactating and suckling rats

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