Chronic Antidepressant Treatment Prevents Accumulation of Gsα in Cholesterol-Rich, Cytoskeletal-Associated, Plasma Membrane Domains (Lipid Rafts)

Abstract

Previous studies demonstrated that Gsa migrates from a Triton X-100 (TTX-100) insoluble membrane domain to a TTX-100 soluble membrane domain in response to chronic treatment with the antidepressants desipramine and fluoxetine. Antidepressant treatment also causes a Gsa redistribution in cells as seen by confocal microscopy. The current studies have focused on examining the possibility that the association between Gsa and the plasma membrane and/or cytoskeleton is altered in response to antidepressant treatment, and that this is relevant to both Gsa redistribution and the increased coupling between Gsa and adenylyl cyclase seen after chronic antidepressant treatment. Chronic treatment of C6 cells with two fuctionally and structurally distinct antidepressants, desipramine and fluoxetine, decreased the Gsa content of TTX-100 insoluble membrane domains by as much as 60%, while the inactive fluoxetine analog LY368514 had no effect. Disruption of these membrane domains with the cholesterol chelator methyl-b-cyclodextrin altered the localization of many proteins involved in the cAMP signaling cascade, but only Gsa localization was altered by antidepressant treatment. In addition, microtubule disruption with colchicine elicited the movement of Gsa out of detergent-resistant membrane domains in a manner identical to that seen with antidepressant treatment. The data presented here further substantiate the role of Gsa as a major player in antidepressant-induced modification of neuronal signaling and also raise the possibility that an interaction between Gsa and the cytoskeleton is involved in this process.

Lateral Diffusion of Gαs in the Plasma Membrane Is Decreased after Chronic but not Acute Antidepressant Treatment: Role of Lipid Raft and Non-Raft Membrane Microdomains

“…This difference was not previously noted in assays of cAMP production or Ga s raft localization (Ozawa and Rasenick, 1989;Donati and Rasenick, 2005), and is perhaps revealed now because of the increased sensitivity and greater sample sizes afforded by the higherthroughput FRAP assay. It is noteworthy in this study that the heterogeneity of effect does not depend on drug class (TCA, SSRI, etc), and is variable within classes.…”

“…Previous experiments have demonstrated increased co-immunoprecipitation of Ga s and adenylyl cyclase after tricyclic antidepressant and electroconvulsive treatment in rat cerebral cortex (Chen and Rasenick, 1995b). Given the increased association between Ga s and adenylyl cyclase after antidepressant treatment (Chen and Rasenick, 1995b;Ozawa and Rasenick, 1989;Donati and Rasenick, 2005), the antidepressant-induced retardation of Ga s FRAP is likely a result of increased association with the relatively slow moving adenylyl cyclase.…”

“…Antidepressant-induced changes in Ga s signaling require several weeks in animal models (Ozawa and Rasenick, 1991) or several days in cells (Donati and Rasenick, 2005), which is also reflected in the decreased GFP-Ga s mobility seen with FRAP (Figure 2b).…”

3β-Methoxy-pregnenolone (MAP4343) as an innovative therapeutic approach for depressive disorders

“…Repeated daily administration (3-4 wk) of different classes of antidepressant drugs have been reported to affect microtubules in the rat hippocampus by changing the ratio of hippocampal α-tubulin isoforms suggestive of increased microtubule dynamics (6,28) and by increasing MAP-2 phosphorylation (22,28). The modulation of microtubule dynamics induced by repeated administrations of antidepressant drugs is a slow process associated to postsynaptic activation of intracellular protein kinases pathways (4) and translocation of Gsa from plasma membrane (29) to cytosol, where it increases microtubule dynamics (30). Therefore, the present data are in favor of additional postsynaptic mechanisms, which may explain the delayed therapeutic efficacy of FLX and other antidepressant drugs.…”

Antidepressants Accumulate in Lipid Rafts Independent of Monoamine Transporters to Modulate Redistribution of the G Protein, Gαs

“…This has been observed in both rats (7) and cell culture (8,16,30). Moreover, lipid raft disruption through cholesterol depletion or cytoskeletal disruption displaces many raft proteins, but GPCR activation or antidepressant treatment displaces only G␣ s (7).…”