title: Reduced platelet G protein-coupled receptor kinase 2 in major depressive disorder: antidepressant treatment-induced upregulation of GRK2 protein discriminates between responder and non-responder patients.
abstract: The homologous regulation of neurotransmitter receptors by G protein-coupled receptor kinases (GRKs) is important in the pathogenesis and treatment of major depressive disorder (MDD). Previous studies have reported that the basal status of GRK2 is different in brains (upregulation) and platelets (downregulation) of subjects with MDD. The principal aim of this study was to re-examine the status of platelet membrane GRK2 protein in patients with MDD, along with GRK3 (a close kinase homolog) and GRK5 (a kinase with different properties), before and after treatment with serotonin-selective reuptake inhibitor (SSRI) or serotonin noradrenaline reuptake inhibitor (SNRI) antidepressants. The main findings indicated that platelet GRK2 and p-Ser670 GRK2 were reduced (36-41%) in unmedicated MDD subjects, and that GRK2 content correlated inversely with the severity of depression (r=-0.51). Effective antidepressant treatments normalized platelet GRK2, and, notably, GRK2 upregulation discriminated between responder and non-responder patients. Other findings revealed a modest reduction of platelet GRK3 (23%) and no alteration of platelet GRK5 content. In untreated subjects with MDD, lymphocyte GRK2 and GRK5 mRNAs were unaltered but antidepressant treatment-induced upregulation of GRK2 mRNA expression. The reduced content of platelet GRK2 protein is a relevant target in MDD. Although this peripheral GRK2 defect does not mirror the canonical regulation of brain GRK2 in depressed suicides, it could well represent a disease state marker as well as a surrogate of response to effective antidepressant treatment.
authors.affiliation: Laboratory of Neuropharmacology, IUNICS, University of the Balearic Islands, Palma de Mallorca, Spain. jesus.garcia-sevilla@uib.es
authors.forename: Jesús A
authors.initials: JA
authors.lastname: García-Sevilla
authors.forename: María
authors.initials: M
authors.lastname: Alvaro-Bartolomé
authors.forename: Rebeca
authors.initials: R
authors.lastname: Díez-Alarcia
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ramos-Miguel
authors.forename: Dolors
authors.initials: D
authors.lastname: Puigdemont
authors.forename: Víctor
authors.initials: V
authors.lastname: Pérez
authors.forename: Enric
authors.initials: E
authors.lastname: Alvarez
authors.forename: J Javier
authors.initials: JJ
authors.lastname: Meana
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D001792:Blood Platelets / Q000378:metabolism*; D003865:Major Depressive Disorder / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D015536:Down-Regulation; D004351:Drug Resistance; D005260:Female; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000097:blood* / Q000235:genetics; D054770:G-Protein-Coupled Receptor Kinase 3 / Q000097:blood / Q000235:genetics; D054774:G-Protein-Coupled Receptor Kinase 5 / Q000097:blood / Q000235:genetics; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics; D011941:Receptors, Adrenergic / Q000378:metabolism; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use; D015854:Up-Regulation
chemical_list: D000928:Antidepressive Agents; D054769:G-Protein-Coupled Receptor Kinase 2; D054770:G-Protein-Coupled Receptor Kinase 3; D054774:G-Protein-Coupled Receptor Kinase 5; D012333:RNA, Messenger; D011941:Receptors, Adrenergic; D017367:Selective Serotonin Reuptake Inhibitors; C496567:GRK2 protein, human; C517848:GRK3 protein, human; C517898:GRK5 protein, human