Thyroid function in post-weaning rats whose dams were fed a low-protein diet during suckling

Abstract

This study was designed to evaluate the thyroid and pituitary hormone levels in post-weaning rats whose dams were fed a low-protein diet during suckling (21 days). The dams and pups were divided into 2 groups: a control group fed a diet containing 22% protein that supplies the necessary amount of protein for the rat and is the usual content of protein in most commercial rat chow, and a diet group fed a lowprotein (8%) diet in which the protein was substituted by an isocaloric amount of starch. After weaning all dams and pups received the 22% protein diet. Two hours before sacrifice of pups aged 21, 30 and 60 days, a tracer dose (0.6 µCi) of 125 I was injected (ip) into each animal. Blood and thyroid glands of pups were collected for the determination of serum T 4 , T 3 and TSH and radioiodine uptake. Low protein diet caused a slight decrease in radioiodine uptake at 21 days, and a significant decrease in T 3 levels (128 ± 14 vs 74 ± 9 ng/dl, P<0.05), while T 4 levels did not change and TSH was increased slightly. At 30 days, T 3 and TSH did not change while there was a significant increase in both T 4 levels (4.8 ± 0.3 vs 6.1 ± 0.2 µg/dl, P<0.05) and in radioiodine uptake levels (0.34 ± 0.02 vs 0.50 ± 0.03%/mg thyroid, P<0.05). At 60 days serum T 3 , T 4 and TSH levels were normal, but radioiodine uptake was still significantly increased (0.33 ± 0.02 vs 0.41 ± 0.03%/mg thyroid, P<0.05). Thus, it seems that protein malnutrition of the dams during suckling causes hypothyroidism in the pups at 21 days that has a compensatory mechanism increasing thyroid function after refeeding with a 22% protein diet. The radioiodine uptake still remained altered at 60 days, when all the hormonal serum levels returned to the normal values, suggesting a permanent change in the thyroid function.

Maternal Food Restriction During Lactation Reduces Mandible Growth of the Female Offspring in Adulthood: Experimental and Morphometric Analysis

“…These findings confirm previous observations (Ramos et al, 1997;Passos et al;Teixeira et al) that undernutrition (ER and PER groups) leads to a lower weight gain from the first day of lactation onwards. The deficiency in body weight gain seen in malnourished offspring could result from a reduction or absence of growth hormone (GH) because food deprivation reduces the number of GH secretory cells, as shown by immunostaining of hypothalamic sections for GH-releasing hormone (GHRH) and quantification of the mRNA levels for GHRH and GH (Brogan et al, 1997;Cónsole et al).…”

Effects of maternal undernutrition during lactation on aromatase, estrogen, and androgen receptors expression in rat testis at weaning

“…This study provides further evidence that early malnutrition can lead to endocrine disruption , Ramos et al 1997, Rocha de Melo & Guedes 1997, Teixeira et al 2002. The maternal nutritional state during lactation is equivalent and possibly even more important than that during gestation, as evidenced by a study from Léonhard et al (2003) that showed that the offspring whose dams were malnourished during lactation had more drastic consequences on gonadal development when compared with the offspring whose dams were malnourished only during pregnancy or during pregnancy and lactation.…”

Maternal Malnutrition Diet During Lactation Period Leads to Incomplete Catch-Up Growth in Femur of the Pups at Adulthood

“…Since bones are vital tissues, they are subject to a variety of disorders ranging from congenital defects, malnutrition, and hormone imbalance due to degenerative and inflammatory diseases and injuries. The development is critically affected by malnutrition, and several studies have examined the effect of nutritional deficiencies on bone growth during gestation (Mehta et al, 2002), lactation (Miller & German, 1999;Fernandes et al, 2007Fernandes et al, , 2008Fetoui et al;Andrade et al) and the post-weaning period (Ramos et al, 1997;Brogan et al, 1997). Thus, growth retardation varies in accordance with the severity and duration of the nutritional deficiency (Jones et al).…”