Physiol. Res. 55: 195-204, 2006

Red Blood Cell Triiodothyronine Uptake as Membrane Parameter of Depression


Department of Psychiatry, First Faculty of Medicine, Charles University, Prague, Czech Republic

Received December 30, 2004
Accepted April 20, 2005
On-line May 24, 2005

We tested the hypothesis considering the role of hypothalamic-pituitary-thyroid axis (HPT), L-triiodothyronine (L-T3) uptake into erythrocytes, and the role of membrane lipids in the development and treatment of affective disorders. Changes in kinetic parameters (Vmax, maximal velocity and KM, apparent Michaelis constant) of L-T3 uptake into red blood cells (RBCs) and changes in membrane fluidity in a group of 24 patients with major depression were measured before treatment and after 1 month of treatment with citalopram. Parameters Vmax and KM, as well as membrane microviscosity, were significantly increased in depressed patients both before and after treatment in comparison with healthy subjects. We concluded that the function of the membrane transporter for L-T3 in RBC is changed in depression. This change is probably connected with alteration of membrane fluidity and/or transporter–lipid interactions. We did not find any normalization of the measured parameters after 1 month of treatment. The results show the importance of composition and physical properties of the lipid bilayer for transmembrane transport of L-T3 and support the hypothesis that the HPT axis is in depression.

Key words
Depression • Erythrocyte • Membrane fluidity • Triiodothyronine • Uptake

© 2006 by the Institute of Physiology, Czech Academy of Sciences