Mécanisme d’échange de la tyrosine entre le plasma et les érythrocytes chez le sujet normal et des patients psychiatriques

Abstract

The saturable mechanism of tyrosine (TYR) uptake by the membrane of red blood cells incubated at 37 °C has been studied in normal subjects and psychiatric patients. This uptake is markedly inhibited by incubation at 0 °C, and weakly inhibited by iodoacetic acid and ouabain. The uptake of TYR is significantly lower in unipolar- and bipolar-depressed patients, and significantly higher in schizophrenics compared to normal controls. These results indicate a possible disturbance of functional capacity of membrane transport in some psychiatric diseases.

In vitro Effects of lonophores and Inhibitors of Main Sodium and Calcium Movements on Tyrosine and Tryptophan Transport by Human Erythrocytes

“…In a previous paper, we described a deficit of TYR transport in vitro by these cells from psychiatric patients [Widmer et al, 1982]. This finding has been confirmed by more recent studies .…”

“…The decrease of specific TYR transport, observed only after sanguinarine, could be compared with the action of ouabain, as shown in a previous study, and suggests a small contribution of the active sodium move ment on this amino acid transport [Widmer et al, 1982], We used this alkaloid because it seems to be more potent on the (Na+, K+) ATPase than classical cardiotonics but with no binding to the ouabain receptors [Cala et al, 1982],…”

“…The activity of this system often described to be low in psychiatric conditions and where the lithium cation is implicated might explain at least partly the abnormal rate of transport of TYR and TRP observed in a similar population [Widmer et al, 1982;Rybakowski et al, 1984;. Little modifications of these transports with a maximum range of 20% could be observed after having used other drugs acting on the movements of the electrolytes.…”

“…These peripheral indices might be specific markers in various psychiatric conditions [Widmer et al, 1982;Rotman, 1983;Siever and Coursey, 1985;Widmer et al, 1985], TYR and TRP are carried across the membrane of human red blood cells by the L (TYR) and T (TRP) transport systems. These transports are characterized by low affinity, sensitivity to temperature and composition of incubation medium, and by competition with other amino acids.…”

A Multivariate Analysis of Red Blood Cell Membrane Transports and Plasma Levels of <i>L</i>-Tyrosine and <i>L</i>-Tryptophan in Depressed Patients before Treatment and after Clinical Improvement

“…In previous observations, Tissot et al [1978] showed that monoamine precursors (L-tyrosine and L-tryptophan) exhibit modifications of their erythrocyte mem brane transports and plasma levels in depressed patients compared to controls Pringuey et al, 1986;Widmer et al, 1982]. Further, clinical improve ment correlates with normalization of these biochemical parameters [Bovier et al, 1988], Plasma red cell trans ports of tyrosine and tryptophan were then hypothesized to be valuable biological markers in affective disorders: abnormalities in the function of brain neurotransmitters could be implicated in their etiology.…”