Density of guanine nucleotide-binding proteins in platelets of patients with major depression: increased abundance of the G alpha i2 subunit and down-regulation by antidepressant drug treatment.
The aim of this study was to quantitate the density of guanine nucleotide-binding (G) protein subunits (inhibitory G alpha i, stimulatory G alpha s, G alpha q/11, and G beta) in platelets of unipolar depressed patients to assess the status of these signal transduction proteins in depression and the effects of antidepressant drug treatment. Blood platelets were collected from 22 drug-free depressed patients and 22 age- and sex-matched healthy controls. The levels of the various G protein subunits were assessed by immunoblotting techniques. The immunoreactivity of G alpha 12 was increased (41%) and that of G alpha i3 decreased (25%) in platelets of depressed patients. The levels of other G protein subunits (G alpha s, G alpha q/11, G beta) did not change significantly with respect to those of control subjects. Chronic administration of cyclic antidepressant drugs (citalopram, clomipramine, imipramine) decreased the immunoreactivity of the up-regulated G alpha i2 protein (31%). Since platelet G alpha i2 is in line with the existence of supersensitivity of these receptors in major depression.
García-Sevilla
J A
JA
Department of Psychiatry, Medical School, University of Geneva, Switzerland.
Walzer
C
C
Busquets
X
X
Escribá
P V
PV
Balant
L
L
Guimón
J
J
D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D015283:Citalopram / Q000627:therapeutic use; D002997:Clomipramine / Q000627:therapeutic use; D003866:Depressive Disorder / Q000188:drug therapy* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000187:drug effects / Q000502:physiology; D019204:GTP-Binding Proteins / Q000097:blood / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007099:Imipramine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010555:Personality Inventory; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
D000928:Antidepressive Agents; D018341:Receptors, Adrenergic, alpha-2; D015283:Citalopram; D019204:GTP-Binding Proteins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002997:Clomipramine; D007099:Imipramine