Environmental stimuli during critical developmental stages establish long-term physiological and structural patterns that “program” health during adult life. Little is known about how alterations in hormonal supply might have consequences in metabolic and thyroid programming. This work aims to prove that alterations in the supply of thyroid hormones during gestation and lactation have long-term consequences in the metabolic and thyroid programming of the offspring. Female Wistar rats were divided into euthyroid, hypothyroid, and hypothyroid with 20 μg/day of s.c. thyroxine (T4), replacement wet nurses. Rats were mating, and after birth, pups were grouped according to their wet nurses group. Milk quality of wet nurses was assessed on days 7, 14, and 21. Body mass gain and energy intake of the offspring were monitored for 28 weeks after weaning. At sacrifice, we extracted and weighed their thyroid gland and adipose reserves, and collected blood to measure its metabolic and thyroid profiles. Hypothyroid wet nurses presented a persistent low quality of milk, while both male and female hypothyroid offspring presented lower body mass gain, higher blood glucose, dyslipidemia, hyperinsulinemia, and hyperleptinemia, as well as lower total adipose reserves, but higher visceral reserve, diminished T3 and T4 concentrations, and lower weight of thyroid gland. Thyroxine replacement prevented all changes in both wet nurses and pups. We conclude that maternal thyroid hormone deficiency during congenital and lactation stages alters the metabolic and thyroid programming of the offspring, while the reestablishment of maternal thyroid status during critical periods of development can prevent these alterations.
Objective: Determine the milk quality effect during lactation on the metabolic and thyroid programming of hypothyroid offspring. Materials and methods: Ten-week-old female Wistar rats were divided into two groups: euthyroid and thyroidectomy-caused hypothyroidism. The rats were matted and, one day after birth, the pups were divided into three groups: euthyroid offspring (EO), hypothyroid offspring (HO) and hypothyroid with a euthyroid replacement wet nurse (HRO). During lactation, the milk quality and offspring body length were evaluated. The body weight and energy intake were determined on a weekly basis, as well as the metabolic profile at the prepubertal (P35-36) and postpubertal (P55-56) ages. At P56, the animals were sacrificed, the adipose tissues were weighed and the thyroid glands were dissected for histological processing. Results: The milk of the hypothyroid wet nurse decreases proteins (16-26%), lipids (22-29%) and lactate (22-37%) with respect to euthyroid. The HO has a lower body weight gain (23-33%), length (11-13%) and energy intake (15-21%). In addition, HO presents impaired fasting glucose and dyslipidemia, as well as a reduction in seric thyroid hormone (18-34%), adipose reserves (26-68%) and thyroid gland weight (25-34%). The HO present thyroid gland cytoarchitecture alteration. The HRO develop the same metabolic alterations as the HO. However, the thyroid gland dysfunction was partially prevented because the HRO improved under about 10% of the serum thyroid hormone concentration, the thyroid gland weight although histological glandular changes presented. Conclusions: The replacement of hypothyroid offspring with a euthyroid wet nurse during lactation can improve the thyroid programming without modifying metabolic programming.
Thyroid hormone deficiency during crucial stages of development causes congenital hypothyroidism. This syndrome alters hypothalamic pathways involved in long-term bodyweight regulation as ObRb-STAT3 leptin signaling pathway, which is associated with metabolic syndrome. This study aimed to determine if thyroxine treatment during pregnancy and lactation in hypothyroid mothers avoids, in the congenital hypothyroid offspring, the alterations in metabolic programming related to metabolic syndrome and the ObRb-STAT3 leptin signaling pathway in hypothalamus. Twenty-four virgin female Wistar rats were divided into euthyroid, hypothyroid, and hypothyroid with thyroxine treatment (20 μg/kg/day T4 since pregnancy until lactation). The bodyweight and energy intake, insulin resistance, glucose tolerance, metabolic and hormonal parameters were determined in offspring at 28 weeks after birth. Then, the rats were euthanized to obtain adipose tissue reserves and hypothalamus to measure the expression of ObRb, STAT3, pSTAT3, and SOCS3. Congenital hypothyroidism presented metabolic syndrome such as insulin resistance, glucose tolerance, dyslipidemias, an increase in cardiovascular risk (Castelli I males:166.67%, females: 173.56%; Castelli II males: 375.51%, females: 546.67%), and hypothalamic leptin resistance (SOCS3, Males: 10.96%, females: 25.85%). Meanwhile, the thyroxine treatment in the mothers during pregnancy and lactation prevents the metabolic disturbance. In conclusion, thyroxine treatment during the critical perinatal stage for metabolic programming prevents congenital hypothyroidism-caused metabolic syndrome and hypothalamic leptin resistance.
Introduction Congenital hypothyroidism affects metabolic and thyroid programming, having a deleterious effect on bodyweight regulation promoting metabolic diseases. This work aimed to demonstrate the development of type 2 diabetes mellitus (T2D) in animals with congenital hypothyroidism, only by the consumption of a mild hypercaloric diet in the extrauterine stage. Methods Two groups of female Wistar rats (n = 9): euthyroid and hypothyroid were used. Hypothyroidism was induced by a thyroidectomy with parathyroid reimplantation. Male offsprings post-weaning were divided into four groups (n = 10): euthyroid, hypothyroid, euthyroid + hypercaloric diet, and hypothyroid + hypercaloric diet. The hypercaloric diet consisted of ground commercial feed plus 20% lard and was administered until postnatal week 40. Bodyweight and energy intake were monitored weekly. Also, metabolic and hormonal markers related to cardiovascular risk, insulin resistance, and glucose tolerance were analyzed at week 40. Then, animals were sacrificed to perform the morphometric analysis of the pancreas and adipose tissue. Results T2D was developed in animals fed a hypercaloric diet denoted by the presence of central obesity, hyperphagia, hyperglycemia, dyslipidemia, glucose tolerance, insulin resistance and hypertension, as well as changes in the cytoarchitecture of the pancreas and adipose tissue related to T2D. The results show that congenital hypothyroid animals had an increase in metabolic markers and an elevated cardiovascular risk. Conclusions Congenital hypothyroid animals develop T2D, having the highest metabolic disturbances and a worsened clinical prognosis than euthyroid animals.
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