title: Neurosteroid analogues. 16. A new explanation for the lack of anesthetic effects of δ(16)-alphaxalone and identification of a δ(17(20)) analogue with potent anesthetic activity.
abstract: This study addresses the hypothesis that the lack of anesthetic activity for (3α,5α)-3-hydroxypregn-16-ene-11,20-dione (Δ(16)-alphaxalone) is explained by the steroid Δ(16) double bond constraining the steroid 20-carbonyl group to a position that prevents it from favorably interacting with γ-aminobutyric acid type A (GABA(A)) receptors. A series of Δ(16) and Δ(17(20)) analogues of Δ(16)-alphaxalone was prepared to evaluate this hypothesis in binding, electrophysiological, and tadpole anesthesia experiments. The results obtained failed to support the hypothesis. Instead, the results indicate that it is the presence of the C-21 methyl group in Δ(16)-alphaxalone, not the location of the constrained C-20 carbonyl group, that prevents Δ(16)-alphaxalone from interacting strongly with the GABA(A) receptor and having anesthetic activity. Consistent with this conclusion, a Δ(17(20)) analogue of Δ(16)-alphaxalone without a C-21 methyl group was found to be very similar to the anesthetic steroid (3α,5α)-3-hydroxypregnane-11,20-dione (alphaxalone) with regard to time of onset and rate of recovery from anesthesia when administered to mice by tail vein injection.
authors.affiliation: Department of Developmental Biology, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Stastna
authors.forename: Kathiresan
authors.initials: K
authors.lastname: Krishnan
authors.forename: Brad D
authors.initials: BD
authors.lastname: Manion
authors.forename: Amanda
authors.initials: A
authors.lastname: Taylor
authors.forename: Nigam P
authors.initials: NP
authors.lastname: Rath
authors.forename: Zi-Wei
authors.initials: ZW
authors.lastname: Chen
authors.forename: Alex S
authors.initials: AS
authors.lastname: Evers
authors.forename: Charles F
authors.initials: CF
authors.lastname: Zorumski
authors.forename: Steven
authors.initials: S
authors.lastname: Mennerick
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Covey
mesh_terms: D000771:Anesthesia, Intravenous; D000777:Anesthetics / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D000818:Animals; D007814:Larva / Q000187:drug effects; D051379:Mice; D015394:Molecular Structure; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011277:Pregnanediones / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D011283:Pregnenes / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: C560302:3-hydroxy-11-oxopregn-17(20)-ene-21-nitrile; D000777:Anesthetics; D011277:Pregnanediones; D011283:Pregnenes; D011963:Receptors, GABA-A; C006477:alphaxalone