Morpho-functional characteristics of rat fetal thyroid gland are affected by prenatal dexamethasone exposure

Adverse perinatal conditions and the developmental origins of thyroid dysfunction-Lessons from Animal Models

PURPOSE

Nutritional, hormonal, and environmental status during development can predispose the individual to obesity and endocrine diseases later in life, an association known as metabolic programming. In general, weight loss or gain are seen in thyroid disorders, and thyroid function can be affected by body adiposity. In addition, hyper- and hypothyroidism can be related to metabolic programming. Our aim was to gather evidence that regardless of the type or critical window of metabolic imprinting, offspring exposed to certain adverse perinatal conditions have a higher risk of developing thyroid dysfunction.

METHODS

We reviewed literature data that relate insults occurring during pregnancy and/or lactation to short- and long-term offspring thyroid dysfunction in animal models.

RESULTS

Few studies have addressed the hypothalamic-pituitary-thyroid axis and thyroid dysfunction related to metabolic programming. The literature shows that under- and overnutrition, exposure to endocrine disruptors, early weaning, maternal thyroid disease and maternal high-fat diet can induce alterations in offspring thyroid function in a sex-dependent manner.

CONCLUSION

Based on the few available data, mainly in rodent models, we can conclude that diet, hormones, and environmental contaminants are related to the developmental origins of later thyroid dysfunction by interrupting the normal maturation of the thyroid gland.

Congenital Adrenal Hyperplasia-Current Insights in Pathophysiology, Diagnostics, and Management

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders affecting cortisol biosynthesis. Reduced activity of an enzyme required for cortisol production leads to chronic overstimulation of the adrenal cortex and accumulation of precursors proximal to the blocked enzymatic step. The most common form of CAH is caused by steroid 21-hydroxylase deficiency due to mutations in CYP21A2. Since the last publication summarizing CAH in Endocrine Reviews in 2000, there have been numerous new developments. These include more detailed understanding of steroidogenic pathways, refinements in neonatal screening, improved diagnostic measurements utilizing chromatography and mass spectrometry coupled with steroid profiling, and improved genotyping methods. Clinical trials of alternative medications and modes of delivery have been recently completed or are under way. Genetic and cell-based treatments are being explored. A large body of data concerning long-term outcomes in patients affected by CAH, including psychosexual well-being, has been enhanced by the establishment of disease registries. This review provides the reader with current insights in CAH with special attention to these new developments.

Congenital adrenal hyperplasia

Congenital adrenal hyperplasia is a disease in which a gene mutation, which is inherited in an autosomal recessive manner, causes a disorder in the synthesis of enzymes that create glucocorticoids, mineralocorticoids, or sex steroids from adrenal cholesterol. The incidence of the classic form of the disease ranges from 1:14000 to 1:18000 births. In the majority of cases, the disease is caused by mutations in the CYP21A2 gene that participates in the synthesis of the 21 Alpha-hydroxylase. Due to the lack of enzymes, the synthesis of cortisol is blocked with the accumulation of sex hormones. The classic form of the disease, or a simple virilizing form in which patients lose salt, is diagnosed in the infant period. In the non-classical or mild form of the disease, with late-onset, patients may be asymptomatic or with a milder form of virilization postnatally. The diagnosis is made based on 17-hydroxyprogesterone levels, in order to determine the deficiency of the 21 Alpha-hydroxylase enzyme. Common complications of the disease are adrenal crisis, hypoglycemia, infertility, and premature entry into puberty. Prenatal therapy is referred to as experimental treatment, while the basis of care is hydrocortisone replacement. In severe forms of the disease, patients are unable to produce enough cortisol in response to stress from gastroenteritis, surgery, trauma, or fever, requiring higher doses of hydrocortisone. In certain cases of genital uncertainty, surgical treatment is necessary. A multidisciplinary team of experts is necessary for adequate surveillance of the disease, in both childhood and adulthood.

Functional Status of Hypothalamic-Pituitary-Thyroid and Hypothalamic-Pituitary-Adrenal Axes in Hospitalized Schizophrenics in Shanghai

OBJECTIVE

Neuroendocrine dysfunction is related to the pathogenesis of mental disorders, but conclusions from clinical research lack consistency. We aimed to investigate the neuroendocrinal pathophysiology and its correlation with clinical symptoms in patients with schizophrenia.

METHODS

The present cross-sectional study included 486 inpatients with schizophrenia admitted at a psychiatric hospital in Shanghai within one year, and 154 healthy controls (HC) matched on age and gender. The serum hemoconcentrations of thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3), free thyroxine (FT4), adrenocorticotrophic hormone (ACTH), and cortisol (COR) were measured via electrochemical luminescence immunoassay. Pathophysiological conversions of neuroendocrine were then associated with gender, age, age at onset, antipsychotic treatment using hierarchical multiple linear regression.

RESULTS

When compared to HC, the schizophrenia group showed elevated ACTH and COR levels and decreased TT3 and TT4 levels (p's < 0.05). First-episode patients showed lower TSH and higher FT3 and FT4 (p's < 0.05) compared to recurrent patients. Female patients showed higher TSH and lower TT3, FT3, and ACTH levels (p's < 0.05) compared to males. We observed the area under the curve (AUC) of the predictive model to distinguish between schizophrenia and HC to be 0.737 among total samples and between first-episode and recurrent schizophrenia to be 0.890 among subgroups.

CONCLUSIONS

Decreased TT3 and TT4 and elevated ACTH and COR levels appear to be associated with schizophrenia symptoms. The chronic recurrent trait of schizophrenia may cause long-term effects on FT3 and FT4 while changes in thyroid, and adrenal function as a result of mental disorder varied with gender. The pathophysiological parameters provide fair to good accuracy of these models.

The placenta in fetal thyroid hormone delivery: from normal physiology to adaptive mechanisms in complicated pregnancies

Context: Thyroid hormones are indispensable for normal fetal development. Since the fetus depends to a large extent on maternal thyroid hormone supply through the placenta, this challenges maternal thyroid economy. Several molecular mechanisms are involved in placental thyroid hormone transport and metabolism. Chronic pregnancy complications, associated with utero-placental hypoxia, trigger the development of accelerated placental maturation in order to improve fetal-placental exchange to strengthen the offspring's chance of survival. This review provides an overview of normal maternal-fetal thyroid hormone supply and explores the presence of placental adaptive mechanisms in complicated pregnancies with chronical utero-placental hypoxia to improve the thyroid hormone supply to the fetus under pressure, to end with reflections about the long term health consequences.Evidence acquisition: This work is based on a comprehensive literature review of the PubMed and Embase database, including relevant articles from 1969 to June 2018.Conclusions: The placenta is actively involved in fetal thyroid hormone delivery through a combination of stimulatory and inhibitory mechanisms. Parallel with histological adaptations to improve transplacental fetal-maternal exchange, there are indications of placental adaptive mechanisms in thyroid hormone transport and metabolism in case of complicated pregnancies, from animal models and in-vitro experiments. Evidence from human in-vivo studies is limited due to heterogeneity in study populations, small study samples, and technical limitations. Further research is necessary to reveal the role of the placenta in pathological circumstances. The placenta might thus be considered as the infants' black box of pregnancy. Results will contribute to more insights in the concept of fetal programming, which lays the foundations of optimum health, growth, and neurodevelopment across the lifespan.

Congenital Adrenal Hyperplasia Due to Steroid 21-Hydroxylase Deficiency: An Endocrine Society Clinical Practice Guideline

Objective

To update the congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency clinical practice guideline published by the Endocrine Society in 2010.

Conclusions

The writing committee presents updated best practice guidelines for the clinical management of congenital adrenal hyperplasia based on published evidence and expert opinion with added considerations for patient safety, quality of life, cost, and utilization.

Influence of maternal thyroid hormones during gestation on fetal brain development

Thyroid hormones (THs) play an obligatory role in many fundamental processes underlying brain development and maturation. The developing embryo/fetus is dependent on maternal supply of TH. The fetal thyroid gland does not commence TH synthesis until mid gestation, and the adverse consequences of severe maternal TH deficiency on offspring neurodevelopment are well established. Recent evidence suggests that even more moderate forms of maternal thyroid dysfunction, particularly during early gestation, may have a long-lasting influence on child cognitive development and risk of neurodevelopmental disorders. Moreover, these observed alterations appear to be largely irreversible after birth. It is, therefore, important to gain a better understanding of the role of maternal thyroid dysfunction on offspring neurodevelopment in terms of the nature, magnitude, time-specificity, and context-specificity of its effects. With respect to the issue of context specificity, it is possible that maternal stress and stress-related biological processes during pregnancy may modulate maternal thyroid function. The possibility of an interaction between the thyroid and stress systems in the context of fetal brain development has, however, not been addressed to date. We begin this review with a brief overview of TH biology during pregnancy and a summary of the literature on its effect on the developing brain. Next, we consider and discuss whether and how processes related to maternal stress and stress biology may interact with and modify the effects of maternal thyroid function on offspring brain development. We synthesize several research areas and identify important knowledge gaps that may warrant further study. The scientific and public health relevance of this review relates to achieving a better understanding of the timing, mechanisms and contexts of thyroid programing of brain development, with implications for early identification of risk, primary prevention and intervention.

Fetal endocrine therapy for congenital adrenal hyperplasia should not be done

Prenatal treatment of congenital adrenal hyperplasia by administering dexamethasone to a woman presumed to be carrying an at-risk fetus remains a controversial experimental treatment. Review of data from animal experimentation and human trials indicates that dexamethasone cannot be considered safe for the fetus. In animals, prenatal dexamethasone decreases birth weight, affects renal, pancreatic beta cell and brain development, increases anxiety and predisposes to adult hypertension and hyperglycemia. In human studies, prenatal dexamethasone is associated with orofacial clefts, decreased birth weight, poorer verbal working memory, and poorer self-perception of scholastic and social competence. Numerous medical societies have cautioned that prenatal treatment of adrenal hyperplasia with dexamethasone is not appropriate for routine clinical practice and should only be done in Institutional Review Board approved, prospective clinical research settings with written informed consent. The data indicate that this treatment is inconsistent with the classic medical ethical maxim to 'first do no harm'.