Endocrine Abstracts

Objective: The association between thyroid function and mood disorders has long been recognized but little is known about the mechanisms underlying this relationship. Thyroid dysfunction often leads to the development of mental diseases and in patients with affective disorders, 1–4% suffers from hypothyroidism and 4–40% show signs of subclinical hypothyroidism. The aim of the present study was to assess the effects of hypothyroidism on metabolic processes in the brain of Wistar and Wistar-Kyoto rats (an animal model of endogenous depression).

Methods: Study was performed in an animal model of depression (Wistar-Kyoto rats) and model of coexistent depression and hypothyroidism (Wistar-Kyoto rats treated with 6-n-propyl-2-thiouracil - PTU). PTU (0.05%) was administered in drinking water for 3 weeks. The forced swim test, ELISA tests, colorimetric assays, and Western blot were applied to investigate the changes in selected metabolic markers in the frontal cortex and hippocampus.

Results: Three-weeks of PTU administration lead to to increase in TSH and decrease in fT3 and fT4 levels in the plasma of control and Wistar-Kyoto group. In the brain, we observed the diminished concentration of key glycolytic compound: pyruvate, disturbances of the linking the glycolysis metabolic pathway to the citric acid cycle and diminished levels of respiratory chain complexes. Additionally, we observed alternations in brain mitochondrial coupling efficiency.

Conclusions: Obtained results indicate an important contribution of thyroid hormones to brain metabolism in the course of depression.

Acknowledgments: This work was supported by grant no. 2017/25/B/NZ7/01708 National Science Centre, Poland.