Food intake and weight of lactating rats maintained on different protein-calorie diets, and pup growth

Abstract

Studies on rats maintained on low-protein-calorie diets during the lactation period show that food intake decreases. This process results in weight loss and a delay in litter development. The purpose of the present study was to determine the alterations in food intake, maternal weight and litter growth during lactation when dams were exposed to diets with different levels of protein and carbohydrate. Female Wistar rats receiving one of 4 different diets, A (N = 14), B (N = 14), C (N = 9) and D (N = 9), were used. Diet A contained 16% protein and 66% carbohydrate; diet B, 6% protein and 77% carbohydrate; diet C, 6% protein and 66% carbohydrate; diet D, 16% protein and 56% carbohydrate. Thus, C and D diets were hypocaloric, while A and B were isocaloric. The intake of a low-protein diet in groups B and C affected the weight of dams and litters during the last two weeks of lactation, while the low-calorie diets limited the growth of D litters at 21 days compared with A litters, but had no effect on the weight of D dams. Group B showed an increase in intake during the first five days of lactation, resulting in a behavioral calorie compensation due to the increase in carbohydrate content, but the intake decreased during the last part of lactation. Food intake regulation predominantly involves the recruitment of a variety of peripheral satiety systems that attempt to decrease the central feeding command system. Key words and growth of ratsThe increase of food intake during a normal lactation period in rats is the result of high energy requirements associated with the process of milk synthesis. The increased meal frequency during the daytime in the second and third postpartum weeks shows that at extremely high rates of energy expenditure, rats are capable of changing their feeding pattern (1). When lactating rats are subjected to severe malnutrition or offered imbalanced diets (low-protein-high-energy) that suppress food intake, milk production may be impaired due to metabolic changes including muscle protein degradation (2). The study of malnutrition during the lactation period shows that a decrease in food intake involves gastrointestinal and neural regulation.The purpose of the present study was to determine the alterations in food intake, maternal weight and litter growth during lactation when the dams were exposed to

Effects of acute stress on learning and memory processes of malnourished rats

“…This difference in weight up to adult age can be explained by the fact that the body weight of adult rats is determined during the gestation and lactation periods, and it depends on the nutritional conditions existing during these periods (Passos et al, 2000). The reduced protein intake by the dam during lactation period causes quantitative and qualitative alteration in the milk source, including changes in the levels of the amino acids needed for pup growth and development (Cambraia, Vannucchi, & Oliveira, 1997;Passos et al, 2000;Pine et al, 1994).…”

Effects of early protein malnutrition and environmental stimulation on behavioral and biochemical parameters in rats submitted to the elevated plus-maze test

“…32,39,40 The reduced body weight of the pups submitted to protein malnutrition, starting from the first week of life, can be considered a consequence of the protein deficiency in the maternal milk due to the protein-poor food with which the mother was fed. 41,42 The low-protein diet also produced a lower body weight during post-lactation period according to previously reported data.…”

“…41,42 The low-protein diet also produced a lower body weight during post-lactation period according to previously reported data. 14,32,39,40 The lower weight of the litters submitted to environmental enrichment during the lactation period was transient and disappears on the post-lactation period (28-35 days of age). This transient effect could be the result of a forced increase in the physical activity proportioned by the exposition of the pups to different objects in the present in the enriched environment, as well as the energy expended by the interactions with other pups for 1 hour a day in the enriched environment.…”

“…The diets were prepared according to the proportion of nutrients recommended by American institute of nutrition and association of official agriculture chemists with the addition of methionine and choline as described by Cambraia et al 32 Briefly, the diet imposed to the group M was constituted of protein (casein) -6%; corn starch -79.8%; lipids (corn oil) -8%; salt mixture -5%; vitamin mixture 1%; choline 0.2%; and also the methionine (2 g/kg of casein). The diet applied for the group C was composed of protein (casein) -16%; corn starch -69.8%; lipids (corn oil) -8%; salt mixture -5%; vitamin mixture 1%; choline 0.2%; and also methionine (2 g/kg of casein).…”

Desnutrição protéica precoce prejudica memória de ratos testados em diferentes procedimentos de reconhecimento de objetos (Rattus norvegicus)

“…Essa perda foi mais acentuada durante a primeira semana e sofreu uma diminuição nas demais. O período de amamentação demanda um alto gasto energético causado pelos cuidados com os filhotes e com a produção do leite (CAMBRAIA et al, 1997).…”