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Changes in mammary fat pad composition and lipolytic capacity throughout pregnancy

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Abstract

Changes in rat mammary fat pad during pregnancy were assessed by studying differences in the morphology and composition of the pad and in the levels of proteins involved in the accumulation and mobilization of fat stores. During pregnancy, the mammary fat pad weight had increased 1.8-fold by day 20, as compared with control rats. DNA content had increased two-fold by day 13 and remained stable until day 20. Protein content showed a two-fold increase on day 20, compared with control rats. As pregnancy advanced, both the percentage of mammary gland cells with respect to the whole mammary fat pad and the size of the adipocytes increased. The specific content of the different elements of the lipolytic pathway, viz. (α2A-adrenergic receptor (AR), β3-AR, cAMP-dependent protein kinase and hormone-sensitive lipase (HSL)) underwent a decrease as pregnancy progressed, although adenylate cyclase increased greatly. The lipoprotein lipase (LPL) content per gram of tissue increased with pregnancy and the HSL-to-LPL ratio reflected a continuous increase in the triglyceride storage throughout pregnancy. Thus, the mammary fat pad undergoes extensive morphological, compositional and metabolic transformation during pregnancy, attributable to the development of the mammary gland. The various elements of the lipolytic pathway and LPL undergo major changes during the development of the mammary gland focused towards the increase of fat stores and allowing the accumulation of lipid droplets in the epithelial mammary cells and an increase in adipocyte size.

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Acknowledgements

The authors are grateful to Dr. J. Oliver for his help with the preparation of the histological samples and for his useful advice regarding the measurement of the morphometric parameters. We also thank Ms. M. Pocoví for her technical assistance on the preparation of the histological sections.

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Authors and Affiliations

  1. Grup de Metabolisme Energètic i Nutrició. Departament de Biologia Fonamental i Ciències de la Salut. Institut Universitari d’Investigació en Ciències de la Salut (IUNICS), Universitat de les Illes Balears, Palma de Mallorca, Spain

    Esperanza Pujol, Ana M. Proenza, Pilar Roca & Isabel Lladó

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  1. Esperanza Pujol
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  2. Ana M. Proenza
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  3. Pilar Roca
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  4. Isabel Lladó
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Corresponding author

Correspondence to Isabel Lladó.

Additional information

This investigation was supported by the Fondo de Investigaciones Sanitarias (PI021339) of the Spanish Government and by the Conselleria d'Innovació i Energia de la Comunitat Autònoma de les Illes Balears (PRDIB–2002GC4–24). E.P. was supported by a grant from the Spanish Government.

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Pujol, E., Proenza, A.M., Roca, P. et al. Changes in mammary fat pad composition and lipolytic capacity throughout pregnancy. Cell Tissue Res 323, 505–511 (2006). https://doi.org/10.1007/s00441-005-0085-0

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  • DOI: https://doi.org/10.1007/s00441-005-0085-0

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