Acute treatment with the cyclic antidepressant desipramine, but not fluoxetine, increases membrane-associated G protein-coupled receptor kinases 2/3 in rat brain

• Published in: Neuropharmacology Vol. 43; no. 8; pp. 1249 - 1257
• Main Authors: Miralles, A., Asensio, V.J., García-Sevilla, J.A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2002; Elsevier
• Subjects: 5-HT receptors; Animals; Antidepressive Agents, Tricyclic - administration & dosage; beta-Adrenergic Receptor Kinases; Biological and medical sciences; Brain - drug effects; Brain - enzymology; Cell Membrane - drug effects; Cell Membrane - enzymology; Cyclic AMP-Dependent Protein Kinases - biosynthesis; Desipramine; Desipramine - administration & dosage; Fluoxetine; Fluoxetine - administration & dosage; G protein-coupled receptor kinase 2/3; G-Protein-Coupled Receptor Kinase 3; Gene Expression Regulation, Enzymologic - drug effects; Gene Expression Regulation, Enzymologic - physiology; Male; Medical sciences; Neuropharmacology; Pharmacology. Drug treatments; Protein-Serine-Threonine Kinases - biosynthesis; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Rat brain; Rats; Rats, Sprague-Dawley; α 2-Adrenoceptors; 5-HT, 5-hydroxytryptamine (serotonin); Desipramine; Fluoxetine; IOD, integrated optical density; SDS-PAGE, sodium dodecyl sulphate-polyacrylamide gel electrophoresis; GRK, G protein-coupled receptor kinase; ANOVA, analysis of variance; G protein-coupled receptor kinase 2/3; α 2-Adrenoceptors; 5-HT receptors; Rat brain; Membrane protein; Rat; Psychotropic; Serotonine receptor; Reuptake inhibitor; Encephalon; Selective serotonin reuptake inhibitor; α2-Adrenoceptors; Antidepressant agent; Mechanism of action; G protein; Biological receptor; α2-Adrenergic receptor; Serotonin; Enzyme; Transferases; Rodentia; Tricyclic compound; Vertebrata; Mammalia; Protein kinase; Animal; Neurotransmitter
• ISSN: 0028-3908; 1873-7064
• DOI: 10.1016/S0028-3908(02)00306-4

The homologous regulation of receptors is mediated by G protein-coupled receptor kinases (GRKs) which phosphorylate the agonist-activated receptor. This study was designed to assess the in vivo indirect activation of adrenoceptors or 5-HT receptors by the reuptake blocker desipramine or fluoxetine on the cellular distribution of GRK 2/3 in rat brain. Immunoblot analysis (frontal cortex) with a GRK 2 antibody revealed a unique 80 kDa protein (mixed GRK 2/3) in total homogenate (H) and in membrane (P2) and cytosolic (S2) fractions. The proportion of GRK 2/3 in each fraction, relative to that of H, was: P2/H=0.11 and S2/H=0.45. Acute desipramine (noradrenaline reuptake blocker) increased in a dose- (1–30 mg/kg, i.p.) and time- (1–6 h) dependent manner the content of GRK 2/3 in the membrane (P2/H ratios increased by 37–164%). This effect vanished with a prolonged desipramine (30 mg/kg) exposure (24 h). Desipramine did not alter the content of GRK 2/3 in the cytosol (S2/H ratios). Chronic desipramine (10 mg/kg every 24 h) for 14 days did not change significantly the immunodensity of GRK 2/3 in the membrane or the cytosol. The acute administration (2 h) of fluoxetine (5-HT reuptake blocker; 3–30 mg/kg) did not induce significant changes in the content of GRK 2/3 in the membrane (P2/H ratio) or cytosol (S2/H ratio). The results indicate that the in vivo activation of adrenoceptors by desipramine is associated with a time-dependent modulation of membrane-associated GRK 2/3 (i.e. an acute increase in the kinase content which is followed by a return to the basal expression upon repeated treatment). In contrast, the acute in vivo activation of 5-HT receptors induced by fluoxetine does not result in modulation of GRK 2/3.