title: Low-protein diet changes thyroid function in lactating rats.
abstract: Lactating rats were fed with free access to an 8% protein-restricted diet (PR); the control group was fed a 23% protein diet (C). An energy-restricted (pair-fed) group was given the same food as the animals in the control group, but the amounts of food consumed by both PF and PR were about the same. The body weight and serum albumin concentration of PR and PF dams were significantly (P < 0. 05) lower than that of the controls. The PR group had a significant increase in serum-free triiodothyronine (FT3) concentration, 24-hr mammary gland and milk radioiodine (I131) uptake (67%, 278%, and 200%, respectively) as compared with the controls. On the other hand, those animals had a significantly lower serum-free thyroxine (FT4) concentration and 2- and 24-hr thyroid I131 uptake (67%, 64%, and 74%, respectively). Protein malnutrition during lactation did not alter thyroid or liver 5'-deiodinase activity significantly. However, PF dams had a significantly lower (25%) thyroid 5'-deiodinase activity. These data suggest that protein-restricted lactating dams had an adaptive change in the thyroid function, which could be important to increase the transference of iodine or triiodothyronine through the milk to their pups and prevent sequelae of neonatal hypothyroidism.
authors.affiliation: Departamento de Ciências, Faculdade de Formação de Professores de São Gonçalo, Universidade do Estado do Rio de Janeiro, 20550-030 Rio de Janeiro, RJ, Brazil.
authors.forename: C F
authors.initials: CF
authors.lastname: Ramos
authors.forename: C V
authors.initials: CV
authors.lastname: Teixeira
authors.forename: M C
authors.initials: MC
authors.lastname: Passos
authors.forename: C C
authors.initials: CC
authors.lastname: Pazos-Moura
authors.forename: P C
authors.initials: PC
authors.lastname: Lisboa
authors.forename: F H
authors.initials: FH
authors.lastname: Curty
authors.forename: E G
authors.initials: EG
authors.lastname: de Moura
mesh_terms: D000818:Animals; D001835:Body Weight; D018753:Diet, Protein-Restricted / Q000009:adverse effects*; D005260:Female; D007037:Hypothyroidism / Q000503:physiopathology; D007453:Iodide Peroxidase / Q000378:metabolism; D007457:Iodine Radioisotopes; D007774:Lactation / Q000502:physiology*; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000378:metabolism; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D009748:Nutrition Disorders / Q000503:physiopathology; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000032:analysis; D013961:Thyroid Gland / Q000201:enzymology / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D007457:Iodine Radioisotopes; D012709:Serum Albumin; D014284:Triiodothyronine; D013972:Thyrotropin; D007453:Iodide Peroxidase; D013974:Thyroxine