title: Effects of neurosteroids on a model membrane including cholesterol: A micropipette aspiration study.
abstract: Amphiphilic molecules supposed to affect membrane protein activity could strongly interact also with the lipid component of the membrane itself. Neurosteroids are amphiphilic molecules that bind to plasma membrane receptors of cells in the central nervous system but their effect on membrane is still under debate. For this reason it is interesting to investigate their effects on pure lipid bilayers as model systems. Using the micropipette aspiration technique (MAT), here we studied the effects of a neurosteroid, allopregnanolone (3α,5α-tetrahydroprogesterone or Allo) and of one of its isoforms, isoallopregnanolone (3β,5α-tetrahydroprogesterone or isoAllo), on the physical properties of pure lipid bilayers composed by DOPC/bSM/chol. Allo is a well-known positive allosteric modulator of GABAA receptor activity while isoAllo acts as a non-competitive functional antagonist of Allo modulation. We found that Allo, when applied at nanomolar concentrations (50-200 nM) to a lipid bilayer model system including cholesterol, induces an increase of the lipid bilayer area and a decrease of the mechanical parameters. Conversely, isoAllo, decreases the lipid bilayer area and, when applied, at the same nanomolar concentrations, it does not affect significantly its mechanical parameters. We characterized the kinetics of Allo uptake by the lipid bilayer and we also discussed its aspects in relation to the slow kinetics of Allo gating effects on GABAA receptors. The overall results presented here show that a correlation exists between the modulation of Allo and isoAllo of GABAA receptor activity and their effects on a lipid bilayer model system containing cholesterol.
authors: CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125, Italy.
authors: Daniel
authors: D
authors: Balleza
authors: Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy.
authors: Mattia
authors: M
authors: Sacchi
authors: Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 287, Modena, Italy.
authors: Giulia
authors: G
authors: Vena
authors: Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy.
authors: Debora
authors: D
authors: Galloni
authors: Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 287, Modena, Italy.
authors: Giulia
authors: G
authors: Puia
authors: CNR - Istituto di Biofisica, Via De Marini 6, 16149 Genova, Italy.
authors: Paolo
authors: P
authors: Facci
authors: Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Via Campi 213/A, 41125 Modena, Italy; CNR - Istituto Nanoscienze, S3, Via Campi 213/A, 41125, Italy. Electronic address: andrea.alessandrini@unimore.it.
authors: Andrea
authors: A
authors: Alessandrini
mesh_terms: D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D007536:Isomerism; D007700:Kinetics; D008567:Membranes, Artificial; D018377:Neurotransmitter Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000737:chemistry* / Q000378:metabolism; D011280:Pregnanolone / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D013109:Sphingomyelins / Q000737:chemistry* / Q000378:metabolism; D013396:Suction; D013501:Surface-Active Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D008567:Membranes, Artificial; D018377:Neurotransmitter Agents; D010713:Phosphatidylcholines; D011963:Receptors, GABA-A; D013109:Sphingomyelins; D013501:Surface-Active Agents; D002784:Cholesterol; D011280:Pregnanolone; C017251:1,2-oleoylphosphatidylcholine
keywords: Allopregnanolone; Giant unilamellar vesicle (GUV); Micropipette aspiration; Neurosteroids