European scientists have identified in mice a previously unknown group of brain nerve cells, or neurons, that regulate cardiovascular functions such as heart rhythm and blood pressure.
Neurons develop in the brain with the aid of thyroid hormone, which is produced in the thyroid gland. Patients in whom the function of the thyroid gland is disturbed, and who therefore produce too much or too little thyroid hormone, are at risk of developing problems with cells.
Patients with untreated hyperthyroidism (too high a production of thyroid hormone) or hypothyroidism (too low a production of thyroid hormone) often develop heart problems. It has previously been believed that this was solely a result of the hormone affecting the heart directly.
However, a new study published in the Journal of Clinical Investigation shows that thyroid hormone also affects the heart indirectly, through a previously unknown population of so-called parvalbuminergic neurons.
The study reveals that thyroid hormone receptors are required for the development of these cells in a brain area called the anterior hypothalamus.
“This discovery opens the possibility of a completely new way of combating cardiovascular disease,” said lead author Dr Jens Mittag of the Karolinska Institutet’s Department of Cell and Molecular Biology.
“If we learn how to control these neurons, we will be able to treat certain cardiovascular problems like hypertension through the brain. This is, however, still far in the future.”
“A more immediate conclusion is that it is of utmost importance to identify and treat pregnant women with hypothyroidism, since their low level of thyroid hormone may harm the production of these neurons in the foetus, and this may in the long run cause cardiovascular disorders in the offspring,” Dr Mittag concluded.
Bibliographic information: Jens Mittag et al. 2013. Thyroid hormone is required for hypothalamic neurons regulating cardiovascular functions. Journal of Clinical Investigation, 123 (1); doi: 10.1172/JCI65252