Modulation of Ligand-Gated Ion Channels as a Novel Pharmacological Principle

Abstract

The present study investigated the functional antagonism of different antidepressants on 5-HT₃ receptor function and the role of lipid rafts for these modulatory effects. Electrophysiological recordings of 5-HT evoked cation currents were recorded with N1E-115 and HEK-5-HT_3A cells and hippocampal neurons. The characterization of the antagonism of antidepressants was made by the displacement of [³H]GR65630 binding. For membrane fractionation, sucrose density gradient centrifugation was used. Gradient fractions were assayed for antidepressant concentrations by HPLC; 5-HT₃ receptor membrane distribution was determined by Western blot. Colocalization experiments were performed by means of immunocytochemistry. Most antidepressants acted as non-competitive antagonists at the 5-HT₃ receptor. Moreover, some of these compounds were enriched within lipid rafts. Cholesterol depletion impaired lipid raft integrity thereby affecting 5-HT₃ receptor function, whereas the antagonistic effects of antidepressants were not altered.In conclusion, most antidepressants directly antagonize 5-HT₃ receptor activity. 5-HT₃ receptor function per se appears to depend on lipid raft integrity, which is, however, not a prerequisite for the modulatory potency of antidepressants at this receptor.

References

• 1 Allen JA, Halverson-Tamboli RA, Rasenick MM. Lipid raft microdomains and neurotransmitter signalling.  Nat Rev Neurosci. 2007;  8 128-140
• 2 Bari M, Oddi S, De Simone C. et al . Type-1 cannabinoid receptors colocalize with caveolin-1 in neuronal cells.  Neuropharmacology. 2008;  54 45-50
• 3 Barnes NM, Sharp T. A review of central 5-HT receptors and their function.  Neuropharmacology. 1999;  38 1083-1152
• 4 Baumann P, Gaillard JM, Perey M. et al . Relationships between brain concentrations of desipramine and paradoxical sleep inhibition in the rat.  J Neural Transm. 1983;  56 105-116
• 5 Blakely RD. Physiological genomics of antidepressant targets: keeping the periphery in mind.  J Neurosci. 2001;  21 8319-8323
• 6 Breitinger HG, Geetha N, Hess GP. Inhibition of the serotonin 5-HT₃ receptor by nicotine, cocaine, and fluoxetine investigated by rapid chemical kinetic techniques.  Biochemistry. 2001;  40 8419-8429
• 7 Brown DA, Rose JK. Sorting of GPI-anchored proteins to glycolipid-enriched membrane subdomains during transport to the apical cell surface.  Cell. 1992;  68 533-544
• 8 Donati RJ, Dwivedi Y, Roberts RC. et al . Postmortem brain tissue of depressed suicides reveals increased Gs alpha localization in lipid raft domains where it is less likely to activate adenylyl cyclase.  J Neurosci. 2008;  28 3042-3050
• 9 Donati RJ, Rasenick MM. Chronic antidepressant treatment prevents accumulation of gsalpha in cholesterol-rich, cytoskeletal-associated, plasma membrane domains (lipid rafts).  Neuropsychopharmacology. 2005;  30 1238-1245
• 10 Duman RS, Heninger GR, Nestler EJ. A molecular and cellular theory of depression.  Arch Gen Psychiatry. 1997;  54 597-606
• 11 Eisensamer B, Rammes G, Gimpl G. et al . Antidepressants are functional antagonists at the serotonin type 3 (5-HT₃) receptor.  Mol Psychiatry. 2003;  8 994-1007
• 12 Eisensamer B, Uhr M, Meyr S. et al . Antidepressants and antipsychotic drugs colocalize with 5-HT₃ receptors in raft-like domains.  J Neurosci. 2005;  25 10198-10206
• 13 Fan P. Effects of antidepressants on the inward current mediated by 5-HT₃ receptors in rat nodose ganglion neurones.  Br J Pharmacol. 1994;  112 741-744
• 14 Fan P. Inhibition of a 5-HT₃ receptor-mediated current by the selective serotonin uptake inhibitor, fluoxetine.  Neurosci Lett. 1994;  173 210-212
• 15 Fletcher S, Barnes NM. Desperately seeking subunits: are native 5-HT₃ receptors really homomeric complexes?.  Trends Pharmacol Sci. 1998;  19 212-215
• 16 Hannon J, Hoyer D. Molecular biology of 5-HT receptors.  Behav Brain Res. 2008;  195 198-213
• 17 Holsboer F, Barden N. Antidepressants and hypothalamic-pituitary-adrenocortical regulation.  Endocr Rev. 1996;  17 187-205
• 18 Hussy N, Lukas W, Jones KA. Functional properties of a cloned 5-hydroxytryptamine ionotropic receptor subunit: comparison with native mouse receptors.  J Physiol. 1994;  481 (Pt 2) 311-323
• 19 Karson CN, Newton JE, Livingston R. et al . Human brain fluoxetine concentrations.  J Neuropsychiatry Clin Neurosci. 1993;  5 322-329
• 20 Kusumi A, Suzuki K. Toward understanding the dynamics of membrane-raft-based molecular interactions.  Biochim Biophys Acta. 2005;  1746 234-251
• 21 Lankiewicz S, Lobitz N, Wetzel CH. et al . Molecular cloning, functional expression, and pharmacological characterization of 5-hydroxytryptamine 3 receptor cDNA and its splice variants from guinea pig.  Mol Pharmacol. 1998;  53 202-212
• 22 Maricq AV, Peterson AS, Brake AJ. et al . Primary structure and functional expression of the 5HT₃ receptor, a serotonin-gated ion channel.  Science. 1991;  254 432-437
• 23 Nakagawa Y, Ishima T, Takashima T. The 5-HT₃ receptor agonist attenuates the action of antidepressants in the forced swim test in rats.  Brain Res. 1998;  786 189-193
• 24 Nothdurfter C, Tanasic S, Di Benedetto B. et al . Impact of lipid raft integrity on 5-HT₃ receptor function and its modulation by antidepressants.  Neuropsychopharmacology. 2010;  35 1510-1519
• 25 Pacher P, Kohegyi E, Kecskemeti V. et al . Current trends in the development of new antidepressants.  Curr Med Chem. 2001;  8 89-100
• 26 Pike LJ. Lipid rafts: heterogeneity on the high seas.  Biochem J. 2004;  378 281-292
• 27 Rammes G, Eisensamer B, Ferrari U. et al . Antipsychotic drugs antagonize human serotonin type 3 receptor currents in a non-competitive manner.  Mol Psychiatry. 2004;  9 846-858
• 28 Reeves DC, Lummis SC. Detection of human and rodent 5-HT_3B receptor subunits by anti-peptide polyclonal antibodies.  BMC Neurosci. 2006;  7 27
• 29 Rodgers RJ, Cole JC, Tredwell JM. Profile of action of 5-HT₃ receptor antagonists, ondansetron and WAY 100289, in the elevated plus-maze test of anxiety of mice.  Psychopharmacology. 1995;  117 306-312
• 30 Rupprecht R. Neuroactive steroids: mechanisms of action and neuropsychopharmacological properties.  Psychoneuroendocrinology. 2003;  28 139-168
• 31 Smart EJ, Ying YS, Mineo C. et al . A detergent-free method for purifying caveolae membrane from tissue culture cells.  Proc Natl Acad Sci USA. 1995;  92 10104-10108
• 32 Song KS, Li S, Okamato T. et al . Co-purification and direct interaction of ras with caveolin, an integral membrane protein of caveolae microdomains. Detergent-free purification of caveolae microdomains.  J Biol Chem. 1996;  271 9690-9697
• 33 Sugita S, Shen KZ, North RA. 5-hydroxytryptamine is a fast excitatory transmitter at 5-HT₃ receptors in rat amygdala.  Neuron. 1992;  8 199-203
• 34 Tsui-Pierchala BA, Encinas M, Milbrandt J. et al . Lipid rafts in neuronal signaling and function.  Trends Neurosci. 2002;  25 412-417
• 35 van Hooft JA, Vijverberg HP. 5-HT(3) receptors and neurotransmitter release in the CNS: a nerve ending story?.  Trends Neurosci. 2000;  23 605-610
• 36 Ye JH, Ponnudurai R, Schaefer R. Ondansetron: a selective 5-HT(3) receptor antagonist and its applications in CNS-related disorders.  CNS Drug Rev. 2001;  7 199-213

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