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Journal of Lipid Research, Vol. 46, 1320-1330, June 2005
Copyright © 2005 by American Society for Biochemistry and Molecular Biology

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

María Belén Hapon^*, Silvia M. Varas, Graciela A. Jahn^* and María S. Giménez^1,

^* Laboratorio de Reproducción y Lactancia, IMBECU-CRICYT-CONICET, 5500 Mendoza, Argentina
Laboratorio de Bioquímica Molecular, Departamento de Bioquímica y Ciencias Biológicas, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, 5700 San Luis, Argentina

Published, JLR Papers in Press, March 1, 2005. DOI 10.1194/jlr.M400325-JLR200

¹ To whom correspondence should be addressed. e-mail: mgimenez{at}unsl.edu.ar

Untreated maternal hypothyroidism (hypoT) has serious consequences in offspring development that may result from the effect on lactation of maternal metabolism dysfunction. We studied the effects of prolonged propylthiouracyl (PTU)-induced hypoT (0.1% PTU in drinking water starting 8 days before mating until day 21 of pregnancy or for 30 days in virgin rats) on liver and mammary lipid metabolism and serum lipid concentrations. In virgins, hypoT reduced hepatic mRNAs associated with triglyceride (TG) and cholesterol synthesis (including fatty acid synthase and 3-hydroxy-3-methylglutaryl coenzyme A reductase), and induced lobuloalveolar mammary development. Pregnancy increased hepatic mRNAs associated with TG and cholesterol synthesis and uptake (including LDL receptor) and with lipid oxidation, such as acyl CoA oxidase. HypoT decreased mRNAs and the activity of proteins associated with TG synthesis, and mRNAs associated with cholesterol uptake and lipid oxidation. Pregnancy increased mammary mRNAs related to lipid oxidation and decreased cholesterol synthesis, whereas hypoT decreased mRNAs and activities of proteins associated with TG synthesis and decreased epithelial mammary tissue. Virgin and pregnant hypoT rats had increased circulating VLDL + LDL cholesterol. HypoT decreased circulating TGs in pregnant rats.

The observed effects of hypoT may result in decreased mammary lipid availability. This, along with the decreased epithelial mammary tissue during lactogenesis, may contribute to the future lactational deficit of hypoT mothers.

Abbreviations: ACC, acetyl CoA carboxylase; ACO, acyl CoA oxidase; CPT, carnitine palmitoyl transferase; EC, esterified cholesterol; FC, free cholesterol; GPAT, glycerol-3-phosphate acyltransferase; HMG-CoAR, 3-hydroxy-3-methylglutaryl coenzyme A reductase; hypoT, hypothyroidism; LDLR, LDL receptor; MG, mammary gland; PTU, propylthiouracyl; T₃, triiodothyronine; T₄, tetraiodothyronine; TG, triglyceride

Supplementary key words mammary gland • lipids • pregnancy • cholesterol • triglycerides • RT-PCR

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				M. B. Hapon, A. B Motta, M. Ezquer, M. Bonafede, and G. A Jahn Hypothyroidism prolongs corpus luteum function in the pregnant rat Reproduction, January 1, 2007; 133(1): 197 - 205. [Abstract] [Full Text] [PDF]