Adaptive changes in thyroid function of female rats fed a high-fat and low-protein diet during gestation and lactation

Abstract

The percent of lipids in the western diet has been continuously increasing in the last decades and is associated with a decrease in the proportion of protein intake. Recently, we demonstrated that protein malnutrition during lactation is associated with lower body weight and thyroid hypofunction in female rats and their offspring. Our objective in the present study was to determine if a high-fat and lowprotein diet was associated with similar changes. Three-month-old female Wistar rats were randomly assigned to one of the following groups with 8 animals each: high-fat and low-protein (40% lipid, 5% protein, and 55% carbohydrate of the total energy content) from the 3rd week of gestation to the end of lactation; control group -standard diet (11% lipid, 23% protein, and 66% carbohydrate of the total energy content). Food consumption and body weight were monitored daily. Serum thyrotropin and thyroid hormone concentrations were determined by specific radioimmunoassay at the end of lactation. Animals receiving high-fat and low-protein diet had a significantly lower body weight (13.9% at weaning, P < 0.05) and serum albumin (25%, P < 0.05) and thyrotropin (26.2%, P < 0.01) concentrations, and a higher serum triiodothyronine concentration (74%, P < 0.005) and 131 I-thyroid uptake (77%, P < 0.005). These data show that a high-fat and low-protein diet can promote maternal thyroid hyperfunction that differs from the thyroid hypofunction observed in dams fed a lowprotein diet, a phenomenon that can be of adaptive importance for pup nurturing.

Experimental diet based on the foods listed in the Family Budget Survey is more detrimental to growth than to the reflex development of rats

“…A similar result was found by Brito et al, 9 who reported that dams fed a high-fat (24.2%) and low protein (7.0%) diet consumed less food during pregnancy, resulting in 82.0% less protein intake and 23.0% less energy intake, but fat intake was three times higher.…”

“…The significant decrease in food and energy intakes caused the POFG dams to lose a considerable amount of weight. Brito et al (2006) 9 also observed that dams fed a high-fat (24.2%), low-protein (7.0%) diet had lost 14.0% more weight by the end of the lactation period than the controls. During lactation, the negative weight gain coefficient per energy intake of the POFG is in agreement with their greater weight loss.…”

“…Rats. [grupo-controle: 12,00 (9,(0)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)00) dias; POFG=9,50 (9,(0)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)00) dias] e queda livre [grupo-controle:18,00 (17,00); POFG=16,00 (13,(0)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)…”

“…During lactation, consumption of high-fat, low-protein diets seems to increase serum triiodothyronine by 74.0% and decrease thyroid-stimulating hormone by 26.0%. These changes induce thyroid hyperfunction, promoting greater iodine uptake and T3 9 synthesis, which in turn promotes greater energy expenditure and weight loss.…”

Effects of Thymoquinone on Plasma Leptin, Insulin, Thyroid Hormones and Lipid Profile in Rats Fed A Fatty Diet

“…Brito et al [24] reported that a high fat and low-protein diet could have a direct effect on TSH secretion or influence pituitary T 4 uptake or deiodination. In this study, all thyroid hormones, in parallel with leptin levels, significantly increased in the FD group as compared to the control group.…”