Changes in lymphocyte proliferation and animal behaviour induced by thyroid hormones.

ALICIA KLECHA, GABRIELA GORELIK, ANA GENARO, MARÍA LAURA BARREIRO ARCOS, RICARDO CARO, GRACIELA CREMASCHI.

Edimburgo, Escocia

Congreso; VI Congress of the International Society of Neuroinmunology; 2001

International Society of Neuroimmunology (ISNI)

  Modulation of lymphocyte activity by thyroid hormones and ß-adrenergic agonists has been described.  Here we studied the effect of thyroid hormone levels on animal behaviour,  lymphoid proliferation and ß-adrenergic receptors (ßAR).  All parameters were measured on normal, hyperthyroid or hypothyroid mice. T and B cell mitogenic stimulation of hyperthyroid lymphocytes showed higher stimulation indexes (SI) than control cells, while those from hypothyroid animals displayed the lowest SI values. Concomitantly, behaviour studies by Open-field showed increased and reduced motor activity in hyperthyroid and hypothyroid respectively. These effects were related to seric levels of thyroid hormones. Isoproterenol-induced increment in lymphoid cAMP levels was higher in hyperthyroid B and T cells than in control, being lower in hypothyroid cells. This was accompanied by a significant increase in ßAR from hyperthyroid B and T lymphocytes respect to control cells and a decrease in ß-adrenergic sites in hypothyroid cells. Triiodothyronine replacement treatment of hypothyroid animals reverted all the effects observed in these animals.  Protein kinase C activity was increased in hyperthyroid, but decreased in hypothyroid lymphocytes.  These results suggest that seric thyroid hormone levels induce both changes in animal behaviour and in lymphocyte activity.  This modulation of lymphocyte proliferation involves altered ßAR expression. The exact mechanisms participating in these interactions are under study.  Supported by Ministerio de Salud.