Document Type

Article

Embargo Period

1-1-2002

Publication Date

1-1-2002

Abstract

An elevation of I1 (imidazoline-1)-binding sites on platelets may be a state marker for depression. Herein, platelet I1 sites were compared in two groups of unipolar depressed patients given different regimens of bupropion treatment : Regimen 1 (n=13 titrated up to 300 mg}d by week 4 and held constant until week 6) ; Regimen 2 (n=15 titrated up to 300 mg}d by week 2, to 450 mg}d by week 6, and held constant until week 8). Platelet I1 sites were quantified by p-[125I]iodoclonidine binding (0.5–15 nm) and displaced by moxonidine under a saturating concentration of norepinephrine to mask α2-adrenoceptors. I1 Bmax values were confirmed to be high at pretreatment in depressed patients (n=28) compared to healthy control subjects (n=18 ; p=0.02). Highest Bmax values at pretreatment were found in patients who responded worst to treatment. More than two-thirds of patients recovered from depression (69 and 80% in Regimens 1 and 2, respectively) after treatment. Dose and/or time of exposure to bupropion were relevant variables since (1) only Regimen 2 led to platelet I1 down-regulation and (2) the extent of down-regulation correlated with plasma concentrations of bupropion. The data suggest a dissociation exists between I1 down-regulation and therapeutic response, or else platelet I1 down-regulation lags behind clinical antidepressant response before becoming measurable.

Journal

International Journal of Neuropsychopharmacology

DOI

https://doi.org/10.1017/S1461145701002759

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