title: Comparison of Steroid Modulation of Spontaneous Inhibitory Postsynaptic Currents in Cultured Hippocampal Neurons and Steady-State Single-Channel Currents from Heterologously Expressed α1β2γ2L GABA(A) Receptors.
abstract: Neuroactive steroids are efficacious modulators of γ-aminobutyric acid type A receptor (GABA(A)) receptor function. The effects of steroids on the GABA(A) receptor are typically determined by comparing steady-state single-channel open probability or macroscopic peak responses elicited by GABA in the absence and presence of a steroid. Due to differences in activation conditions (exposure duration, concentration of agonist), it is not obvious whether modulation measured using typical experimental protocols can be used to accurately predict the effect of a modulator on native receptors under physiologic conditions. In the present study, we examined the effects of 14 neuroactive steroids and analogs on the properties of spontaneous inhibitory postsynaptic currents (sIPSCs) in cultured rat hippocampal neurons. The goal was to determine whether the magnitude of modulation of the decay time course of sIPSCs correlates with the extent of modulation and kinetic properties of potentiation as determined in previous single-channel studies. The steroids were selected to cover a wide range of efficacy on heterologously expressed rat α1β2γ2L GABA(A) receptors, ranging from essentially inert to highly efficacious (strong potentiators of single-channel and macroscopic peak responses). The data indicate a strong correlation between prolongation of the decay time course of sIPSCs and potentiation of single-channel open probability. Furthermore, changes in intracluster closed time distributions were the single best predictor of prolongation of sIPSCs. We infer that the information obtained in steady-state single-channel recordings can be used to forecast modulation of synaptic currents.
authors.affiliation: Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Sampurna
authors.initials: S
authors.lastname: Chakrabarti
authors.affiliation: Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Mingxing
authors.initials: M
authors.lastname: Qian
authors.affiliation: Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Kathiresan
authors.initials: K
authors.lastname: Krishnan
authors.affiliation: Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Covey
authors.affiliation: Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Steven
authors.initials: S
authors.lastname: Mennerick
authors.affiliation: Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri akk@morpheus.wustl.edu.
authors.forename: Gustav
authors.initials: G
authors.lastname: Akk
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011963:Receptors, GABA-A / Q000096:biosynthesis*; D013256:Steroids / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D011963:Receptors, GABA-A; D013256:Steroids