Effects of hypothyroidism on mammary and liver lipid metabolism in virgin and late-pregnant rats

Hapon, María Belén; Varas, Silvia M; Jahn, Graciela A.; Giménez, María Sofía

doi:10.1194/jlr.m400325-jlr200

Cited by 37 publications

(44 citation statements)

References 61 publications

(49 reference statements)

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“…Although there is no evidence of a direct or indirect regulation of PGE2 by thyroid hormones, there is sufficient information demonstrating that the circulating concentration of PGE2 is dependent on cholesterol-low density lipoprotein (LDL) levels (Habenicht et al 1986). We have recently shown that circulating LDL-cholesterol is elevated in hypothyroid rats regardless of the reproductive state (Hapon et al 2005), and this factor may be linked with the observed elevated serum PGE2. Moreover, hypercholesterolemia may directly influence P 4 production, since in vivo and Figure 5 Effect of PTU treatment on luteal mRNA abundance of COX2, iNOS and PGF2aR on days 19 (G19) and 21 (G21) of pregnancy and 2 of lactation (L2).…”

Section: Discussionmentioning

confidence: 99%

Hypothyroidism prolongs corpus luteum function in the pregnant rat

Hapon¹,

Motta²,

Ezquer³

et al. 2007

Reproduction

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It has been shown that hypothyroidism in the rat produces a prolongation of pregnancy associated with a delay in the fall of circulating progesterone (P 4 ) at term. The aim of the present work is to determine whether the delayed P 4 decline in hypothyroid mother rats is due to a retarded induction of P 4 degradation to 20aOH P 4 or to a stimulation of its synthesis, and to investigate the possible mechanisms that may underlie the altered luteal function. We determined by RIA the circulating profile of the hormones (TSH, PRL, LH, P 4 , PGF2a, and PGE2) involved in luteal regulation at the end of pregnancy and, by semiquantitative RT-PCR, the expression of factors involved in P 4 synthesis (CytP450scc, StAR, 3bHSD, PRLR) and metabolism (20aHSD, PGF2aR, iNOS and COX2). Our results show that the delay in P 4 decline and parturition is the resultant of retarded luteal regression, caused by a combination of decreases in luteolytic factors, mainly luteal PGF2a, iNOS mRNA expression and also circulating LH, and increased synthesis or action of luteotrophic factors, such as luteal and circulating PGE2 and circulating PRL. All these changes may be direct causes of the decreased 20aHSD mRNA and protein (measured by western blot analysis) expression, which in the presence of unchanged expression of the factors involved in P 4 synthesis results in elevated luteal and circulating P 4 that prolonged pregnancy and also may favor longer survival of the corpus luteum.

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Section: Discussionmentioning

confidence: 99%

Hypothyroidism prolongs corpus luteum function in the pregnant rat

Hapon¹,

Motta²,

Ezquer³

et al. 2007

Reproduction

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“…The mRNA levels of 7 -hydroxylase are not modified by pregnancy or by hypothyroidism. In addition, the LDL receptor mRNA, a factor involved in cholesterol uptake that is increased during late gestation, is decreased in the pregnant hypothyroid rats, contributing to the increased circulating (LDL+VLDL)-C (Hapon et al, 2005). It is well known that hypothyroidism increases cholesterol through an enhancement of LDL.…”

Section: Liver and Mammary Lipids In Pregnancymentioning

confidence: 99%

“…Changes in thyroid state indirectly modify the biosynthesis of cholesterol by its effects on metabolism and on the coefficient of intestinal absorption of cholesterol (Mathe & Chevallier, 1976). The mRNA levels of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, which is the rate-limiting enzyme for de novo cholesterol biosynthesis, is increased in the liver during late gestation, but the change of 3-hydroxy-3-methylglutarylcoenzyme A reductase is not modified by hypothyroidism (Hapon et al, 2005). The mRNA levels of 7 -hydroxylase are not modified by pregnancy or by hypothyroidism.…”

Section: Liver and Mammary Lipids In Pregnancymentioning

confidence: 99%

“…It is known that pregnancy stimulates fatty acid synthase and glycerol-3-phosphate acyltransferase expressions in the rat liver, while a state of clinical hypothyroidism during pregnancy shows decreased hepatic triglyceride synthesis in terms of 14 C[glucose] incorporation and subsequently, decreases in triglycerides and enhanced cholesterol in the circulation (Bonet & Herrera, 1991;Lopez Luna & Morales, 1985). A decrease in the liver lipid synthesis has been also evidenced by the diminished incorporation of 3 H[H 2 O] into triglycerides and by the expression and activity of fatty acid synthase and acetyl-CoA carboxylase in pregnant hypothyroid rats, which may be responsible for the decrease in circulating triglycerides (Hapon et al, 2005). Congenitally hypothyroid mice show alterations in apoB RNA editing that switch hepatic production from apoB-100 to apoB-48 isoform (Mukhopadhyay et al, 2003), and whose conformational competence directs the assembly of hepatic VLDL more effectively.…”

Section: Liver and Mammary Lipids In Pregnancymentioning

confidence: 99%

“…The regulation and coordination of lipid metabolism on pregnancy and lactation are very important because of the sudden and profound physiological changes occuring during these physiological states (Hapon et al, 2003(Hapon et al, , 2005. It is known that undiagnosed hypothyroidism during pregnancy will lead to irreparable central nervous system defects in the newborn because the development of the child in utero is critically affected by the mother's thyroid status (Gartner, 2009).…”

Section: Hypothyroidism and Lipid During Pregnancy And Lactationmentioning

confidence: 99%

See 2 more Smart Citations

Hypothyroidism on Lipid Metabolism

Mariela¹,

Yamila²,

Liliana³

et al. 2012

Hypothyroidism - Influences and Treatments

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Regulation of glucose transport by thyroid hormone in rat ovary

et al. 2016

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Thyroid hormone (TH) plays an important role in regulating ovarian development. However, the mechanism involved remains unclear. Evidence suggests that glucose is essential for ovarian development, and its uptake is mediated by several glucose transporter proteins (Glut). We have investigated the effects of TH on Glut in rat ovary. Immature rats were treated with 6-propyl-2-thiouracil or L-thyroxine to induce hypothyroidism (hypo) or hyperthyroidism (hyper), respectively. Ovarian weights significantly decreased in both treated groups compared with the control group, although the body weights were not markedly altered. Glut1 expression significantly decreased without further changes being detected in the other Glut isforms in the hypo group and was accompanied by minimal change in mRNA content. The expression of Glut1 decreased in the hyper group. In contrast, L-thyroxine significantly increased Glut4 mRNA level and protein content but had little effect on Glut2 and Glut3 expression. Serum glucose concentrations in the hyper group were dramatically reduced compared with those in the control group. However, the serum glucose levels in the hypo group were not significantly changed. In addition, equine chorionic gonadotropin (eCG) increased ovarian weights in both the hypo and hyper groups compared with those in the rats without eCG injection. Glut2-4 protein content was significantly increased by eCG in hyper rats. Only the Glut4 mRNA content was significantly increased by eCG in the hyper group. Although the mRNA levels were not significantly changed by eCG in the hypo group, the protein level of Glut4 was markedly up-regulated. Serum glucose levels were not significantly altered by eCG in the two groups. Thus, dysfunction of the thyroid gland changes Glut expression in rat ovary and ovarian growth, both of which are also regulated by gonadotropin.

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Effects of hypothyroidism on mammary and liver lipid metabolism in virgin and late-pregnant rats

Cited by 37 publications

References 61 publications

Hypothyroidism prolongs corpus luteum function in the pregnant rat

Hypothyroidism prolongs corpus luteum function in the pregnant rat

Hypothyroidism on Lipid Metabolism

Regulation of glucose transport by thyroid hormone in rat ovary

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