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Glucocorticoids decrease thyrotropin-releasing hormone messenger ribonucleic acid expression in the paraventricular
A Alkemade1, U A Unmehopa, W M Wiersinga
1Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ Amsterdam, The Netherlands. a.alkemade@nih.knaw.nl
The Journal of Clinical Endocrinology and Metabolism
|October 29, 2004
Summary
Glucocorticoids reduce thyrotropin-releasing hormone (TRH) mRNA in the human hypothalamus. This finding in corticosteroid-treated individuals suggests hypercortisolism may lower TRH expression, impacting thyroid function and depression symptoms.
Area of Science:
- Neuroendocrinology
- Molecular Psychiatry
Background:
- The precise impact of glucocorticoids on thyrotropin-releasing hormone (TRH) mRNA expression within the paraventricular nucleus of the hypothalamus remains incompletely understood.
- Understanding this relationship is crucial due to the relevance of glucocorticoids in conditions such as Cushing's syndrome and depression.
Purpose of the Study:
- To investigate the effect of glucocorticoids on TRH mRNA expression in the human hypothalamus.
- To explore the potential mechanisms linking hypercortisolism to altered thyroid-stimulating hormone (TSH) levels and depressive symptoms.
Main Methods:
- Quantitative TRH mRNA in situ hybridization was employed to measure TRH mRNA expression levels.
- Human hypothalami were obtained from autopsy specimens for analysis.
- Subjects were divided into corticosteroid-treated and matched control groups (n=10 each).
Main Results:
- A statistically significant decrease in the TRH mRNA hybridization signal was observed in subjects treated with corticosteroids compared to control subjects (P = 0.02).
- This suggests that exogenous or endogenous glucocorticoid exposure leads to reduced hypothalamic TRH mRNA expression.
Conclusions:
- Glucocorticoid administration or elevated levels appear to suppress TRH mRNA expression in the human paraventricular nucleus.
- These findings infer that hypercortisolism, as seen in Cushing's syndrome and major depression, may contribute to reduced serum TSH or depressive symptoms through diminished hypothalamic TRH expression.