Abstract
During gestation and lactation, a series of metabolic changes that are affected by the diet occurs in various organs of the mother. However, little is known about how the dietary protein (DP)/carbohydrate (DCH) ratio regulates the expression of metabolic genes in the mother. Therefore, the purpose of this work was to study the effect of consuming different percentages of DP/DCH, specifically 10/73, 20/63 and 30/53%, on the expression of genes involved in lipogenesis and protein synthesis in the mammary gland, liver and adipose tissue during gestation and lactation in dams. While the amount of weight gained during gestation was similar for all groups, only dams fed with 30/53% DP/DCH maintained their weight during lactation. In the mammary gland, the expression of the genes involved in lipogenesis, specifically SREBP1 and FAS, was dramatically increased, and the expression of the genes involved in protein synthesis, such as mTOR1, and the phosphorylation of its target protein, S6K, were also increased throughout pregnancy and lactation, regardless of the concentration of DP/DCH. In the liver and adipose tissue, the expression of the genes and proteins involved in lipid metabolism was dependent on the proportion of DP/DCH. The consumption of a low-protein/high-carbohydrate diet increased the expression of lipogenic genes in the liver and adipose tissue and the amount of lipid deposition in the liver. Conversely, the consumption of a high-protein/low-carbohydrate diet increased the expression of genes involved in amino acid oxidation in the liver during gestation. The metabolic adaptations reflected by the changes in the expression of metabolic genes indicate that the mammary gland has a priority for milk synthesis, whereas the adaptations in the liver and adipose tissue are responsible for providing nutrients to the mammary gland to sustain milk synthesis.
Highlights
Several morphological and physiological changes occur in the mammary gland during the processes of gestation and lactation [1,2,3,4]
Our results demonstrate that the regulation of some processes are responsive to the proportion of dietary protein (DP)/dietary carbohydrates (DCH), in the liver and adipose tissue, whereas the mammary gland is an anabolic organ that expresses most of the metabolic genes in a similar fashion, independent of the dietary protein/dietary carbohydrate (DP/DCH) ratio
Little is known about the metabolic adaptations that occur in the different organs of the mother during pregnancy and lactation under different proportions of DP/DCH
Summary
Several morphological and physiological changes occur in the mammary gland during the processes of gestation and lactation [1,2,3,4]. There is an increase in the formation of the epithelial cells, which are involved in milk synthesis, from mammary fat cells [5]. During this stage, several hormones are involved in the regulation of the expression of specific genes to prepare the mammary gland for a successful lactation period [6,7,8,9,10,11,12]. In addition to the diet, during short periods of time, the body organs of the dam can supply nutrients to the mammary gland for the differentiation of cells during gestation, mainly for the synthesis of milk components during lactation. It is known that the liver and the adipose tissue can actively participate in the supply of nutrients to the mammary gland [18,19,20,21,22]
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