5-HT2A-mGlu2/3 receptor complex in rat spinal cord glutamatergic nerve endings: A 5-HT2A to mGlu2/3 signalling to amplify presynaptic mechanism of auto-control of glutamate exocytosis

NEUROPHARMACOLOGY

卷:133

Article

Olivero, Guendalina¹  Grilli, Massimo^1,2  Vergassola, Matteo¹  Bonfiglio, Tommaso¹  Padolecchia, Cristina¹  Garrone, Beatrice³  Di Giorgio, Francesco Paolo³  Tongiani, Serena³  Usai, Cesare⁴  Marchi, Mario^1,2  Pittaluga, Anna^1,2 

[1] DiFAR, Pharmacol & Toxicol Sect, Dept Pharm, Viale Cembrano 4, I-16148 Genoa, Italy

[2] Univ Genoa, Ctr Excellence Biomed Res, Viale Benedetto XV, I-16132 Genoa, Italy

[3] Angelini SpA, Angelini RR&D Res Regulatory & Dev, Piazzale Stn Snc, I-00071 Rome, Italy

[4] CNR, Inst Biophys, Via De Marini 6, I-16149 Genoa, Italy

关键词: mGlu2/3 receptor;    5-HT2A receptor;    Glutamate release;    Spinal cord;    GPCR crosstalk;    Heterocomplex;   

DOI  :  10.1016/j.neuropharm.2018.02.030

来源: Elsevier

【 摘 要 】

Presynaptic mGlu2/3 autoreceptors exist in rat spinal cord nerve terminals as suggested by the finding that LY379268 inhibited the 15 mM KCl-evoked release of [H-3]D-aspartate ([H-3]D-Asp) in a LY341495-sensitive manner. Spinal cord glutamatergic nerve terminals also possess presynaptic release regulating 5-HT2A heteroreceptors. Actually, the 15 mM KCl-evoked [H-3]D-Asp exocytosis from spinal cord synaptosomes was reduced by the 5-HT2A agonist (+/-)DOI, an effect reversed by the 5-HT2A antagonists MDL11,939, MDL100907, ketanserin and trazodone (TZD). We investigated whether mGlu2/3 and 5-HT2A receptors colocalize and cross-talk in these terminals and if 5-HT2A ligands modulate the mGlu2/3-mediated control of glutamate exocytosis. Western blot analysis and confocal microscopy highlighted the presence of mGlu2/3 and 5-HT2A receptor proteins in spinal cord VGLUT1 positive synaptosomes, where mGlu2/3 and 5-HT2A receptor immunoreactivities largely colocalize. Furthermore, mGlu2/3 immunoprecipitates from spinal cord synaptosomes were also 5-HT2A immunopositive. Interestingly, the 100 pM LY379268-induced reduction of the 15 mM MCI-evoked [H-3]D-Asp overflow as well as its inhibition by 100 nM (+/-)DOI became undetectable when the two agonists were concomitantly added. Conversely, 5-HT2A antagonists (MDL11,939, MDL100907, ketanserin and TZD) reinforced the release-regulating activity of mGlu2/3 autoreceptors. Increased expression of mGlu2/3 receptor proteins in synaptosomal plasmamembranes paralleled the gain of function of the mGlu2/3 autoreceptors elicited by 5-HT2A antagonists. Based on these results, we propose that in spinal cord glutamatergic terminals i) mGlu2/3 and 5-HT2A receptors colocalize and interact one each other in an antagonist-like manner, ii) 5-HT2A antagonists are indirect positive allosteric modulator of mGlu2/3 autoreceptors controlling glutamate exocytosis. (C) 2018 Elsevier Ltd. All rights reserved.

【 授权许可】

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