Noradrenaline transporter and its turnover rate are decreased in blood lymphocytes of patients with major depression

Lymphocytes possess transporters of serotonin and dopamine, and also contain monoamines. The objective of this work was to determine the presence of noradrenaline transporters, the turnover rate of noradrenaline and serotonin in lymphocytes of major depression patients, and to correlate the biochemical parameters with the severity of the disorder. Lymphocytes from peripheral blood were isolated by Ficoll/Hypaque, and noradrenaline transporter was studied by binding of [3H]nisoxetine: control group (29, age 31.52 ± 1.08, 7 men) and major depression patients (35, age 36.68 ± 1.69, 6 men), Hospital Vargas de Caracas. Diagnostic was done by criteria of the American Psychiatric Association and severity by Hamilton Scale for Depression. Levels of noradrenaline, serotonin, 3-methoxy-4-hydroxyphenylglycol and 5-hydroxyindoleacetic acid were determined by HPLC. Turnover rate was evaluated by the ratios of monoamines and metabolites. Correlations were done between the biochemical parameters and the severity of depression. The score of Hamilton for Depression was 22.77 ± 0.51. There was a reduction in the number of transporters in lymphocytes of patients, 0.95 ± 0.27 versus 4.06 ± 1.67 fmol/106 cells. Levels of monoamines and metabolites did not significantly differ between patients and controls. However, there was a higher monoamine/metabolite ratio in lymphocytes of patients, indicating a reduction of metabolic turnover rate. Also there was a relative greater concentration of noradrenaline than serotonin in the lymphocytes of the patients, as indicated by the ratio noradrenaline/serotonin. Noradrenergic and serotonergic turnover is decreased in blood peripheral lymphocytes of major depression patients; the reduction in noradrenaline transporter could be related to changes in intracellular levels, and these modifications could result in functional changes of the immune system.