Changes in mammary fat pad composition and lipolytic capacity throughout pregnancy |
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Authors: | Esperanza Pujol Ana M Proenza Pilar Roca Isabel Lladó |
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Institution: | (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;(2) Departament de Biologia Fonamental i Ciències de la Salut. Ed. Guillem Colom, Universitat de les Illes Balears, Cra. Valldemossa, Km 7.5, Palma de Mallorca, 07122, Spain |
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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.
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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Keywords: | Adipocyte Lipolytic pathway Lipoprotein lipase Mammary gland Pregnancy Rat (Wistar) |
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