Platelet I1-imidazoline binding sites are decreased by two dissimilar antidepressant agents in depressed patients.
Previous studies have indicated that there may be a dysregulation of alpha 2-adrenoceptors and imidazoline receptors in depression. This study compares the effects of chronic antidepressant treatment with a serotonin reuptake inhibitor (fluoxetine) versus a noradrenaline reuptake inhibitor (desipramine) on the binding parameters of the platelet imidazoline binding site (subtype I1) and of the platelet alpha 2-adrenoceptor in depressed patients. After 6 weeks of treatment with either antidepressant, platelet I1 binding sites became normalized (i.e. downregulated). A negative correlation was obtained between plasma epinephrine concentrations and platelet alpha 2-adrenoceptor Bmax values within the samples, but no correlation was obtained between any plasma catecholamine and a platelet I1 binding parameter. An additional finding was the increased affinity of alpha 2-adrenoceptors for p125I-clonidine in untreated depressed patients compared to healthy subjects. Because of the density of platelet I1 binding sites was downregulated by both of the antidepressants, we postulate that a decrease in platelet I1 binding site density may be related to an improved state from depression that these antidepressants produce.
Piletz
J E
JE
Department of Psychiatry, University of Mississippi Medical Center, Jackson 39216-4505, USA.
Halaris
A E
AE
Chikkala
D
D
Qu
Y
Y
D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D000328:Adult; D001665:Binding Sites; D001792:Blood Platelets / Q000737:chemistry* / Q000187:drug effects; D003866:Depressive Disorder / Q000097:blood* / Q000188:drug therapy; D003891:Desipramine / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005473:Fluoxetine / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D054755:Imidazoline Receptors; D008297:Male; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects / Q000378:metabolism; D011955:Receptors, Drug / Q000097:blood / Q000187:drug effects*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use
D018759:Adrenergic Uptake Inhibitors; D003891:Desipramine; D005473:Fluoxetine; D054755:Imidazoline Receptors; D018341:Receptors, Adrenergic, alpha-2; D011955:Receptors, Drug; D017367:Selective Serotonin Reuptake Inhibitors