Some metabolic alterations were evaluated in Wistar rats which received control or low-protein (17%; 6%) diets, from the pregnancy until the end of lactation: control non-lactating (CNL), lactating (CL), low-protein non-lactating (LPNL) and lactating (LPL) groups. Despite the increased food intake by LPL dams, both LP groups reduced protein intake and final body mass was lower in LPL. Higher serum glucose occurred in both LP groups. Lactation induced lower insulin and glucagon levels, but these were reduced by LP diet. Prolactin levels rose in lactating, but were impaired in LPL, followed by losses of mammary gland (MAG) mass and, a fall in serum leptin in lactating dams. Lipid content also reduced in MAG and gonadal white adipose tissue of lactating and, in LPL, contributed to a decreased daily milk production, and consequent impairment of body mass gain by LPL pups. Liver mass, lipid content and ATP-citrate enzyme activity were increased by lactation, but malic enzyme and lipid: glycogen ratio elevated only in LPL. Conclusion. LP diet reduced the development of MAG and prolactin secretion which compromised milk production and pups growth. Moreover, this diet enhanced the store of lipid to glycogen ratio and suggests a higher risk of fatty liver development.
resuMoForam avaliadas as alterações no metabolismo materno durante a prenhez em ratas Wistar, prenhes e não-prenhes, submetidas à restrição protéica, que receberam dietas isocalóricas (15,74 kJ/g), controle ou hipoprotéica (17% versus 6%), distribuídas em quatro grupos (n = 7), quais sejam: controle não-prenhe (CNP) e prenhe (CP) e hipoprotéico não-prenhe (HNP) e prenhe (HP), do 1º ao 18º dia de prenhez. Parâmetros bioquímicos, hormonais e relacionados à síntese de lipídios foram considerados. Utilizou-se ANOVA a duas vias seguido de teste Tukey-HSD e teste t de Student, significância de p < 0,05. A restrição protéica elevou a síntese de lipídios e a atividade da enzima málica (EM) no fígado (FIG) e reduziu a massa (%) e a razão lipí+dio/glicogênio nesse tecido, bem como reduziu a ingestão protéica (total e %), o conteúdo (%) de lipídios na glândula mamária (GMA), as proteínas e a albumina séricas, com consequente redução nas massas da placenta e fetos. A prenhez reduziu a proteinemia, a albuminemia, a síntese de lipídios, a atividade da EM, os descritores Restrição protéica; prenhez; metabolismo materno aBstract Metabolism alterations were evaluated in female Wistar rats (dams) during pregnancy. Pregnant and non-pregnant dams submitted to protein restriction, were fed isocaloric (15.74 kJ/g), control or hypoproteic (17% vs. 6%) diets, and distributed in four Groups (n=7) as follows: non-pregnant control (NPC), pregnant control (PC), non-pregnant hypoproteic (NPH), and pregnant hypoproteic (PH); from Day 1 to Day 18 of pregnancy. Biochemical, hormonal and metabolic parameters related to lipid synthesis were assessed. The two-way ANOVA, followed by Tukey-HSD and Student-t tests were used, with a significance of p< 0.05. Protein restriction elevated lipid synthesis and malic enzyme (ME) activity in the liver, and reduced mass and the lipid/glycogen ratio in this tissue; it also lowered protein ingestion (total and %), lipid content (%) in the mammary gland (MAG), serum proteins and albumin, with consequent reduction of placenta and fetal masses. Pregnancy reduced serum protein and albumin concentrations, lipid synthesis, ME activity, hepatic lipid and glycogen content. However, it increased final body mass; increased relative masses of gonad (GON), liver and MAG; but reduced lipid synthesis and content of GON, lipid content of MAG and the relative mass of carcass. Pregnancy Insulinemia increased during pregnancy with reduced glycemia, characterizing hormonal resistance. Leptin and prolactin were also increased during pregnancy, being the highest increase in observed in HP rats. Protein restriction in pregnancy modified maternal metabolism, altering lipid synthesis in the liver and hormonal profile and decreasing the placenta and fetus masses. Arq Bras endocrinol metab. 2009;53(1):87-94.
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