title: Novel, potent, and selective GABAC antagonists inhibit myopia development and facilitate learning and memory.
abstract: This study reports pharmacological and physiological effects of cis- and trans-(3-aminocyclopentanyl)butylphosphinic acid (cis- and trans-3-ACPBPA). These compounds are conformationally restricted analogs of the orally active GABA(B/C) receptor antagonist (3-aminopropyl)-n-butylphosphinic acid (CGP36742 or SGS742). cis-[IC(50)(rho1) = 5.06 microM and IC(50)(rho2) = 11.08 microM; n = 4] and trans-3-ACPMPA [IC(50)(rho1) = 72.58 microM and IC(50)(rho2) = 189.7 microM; n = 4] seem competitive at GABA(C) receptors expressed in Xenopus laevis oocytes, having no effect as agonists (1 mM) but exerting weak antagonist (1 mM) effects on human GABA(A) and GABA(B) receptors. cis-3-ACPBPA was more potent and selective than the trans-compound, being more than 100 times more potent at GABA(C) than GABA(A) or GABA(B) receptors. cis-3-ACPBPA was further evaluated on dissociated rat retinal bipolar cells and dose-dependently inhibited the native GABA(C) receptor (IC(50) = 47 +/- 4.5 microM; n = 6). When applied to the eye as intravitreal injections, cis- and trans-3-ACPBPA prevented experimental myopia development and inhibited the associated vitreous chamber elongation, in a dose-dependent manner in the chick model. Doses only 10 times greater than required to inhibit recombinant GABA(C) receptors caused the antimyopia effects. Using intraperitoneal administration, cis- (30 mg/kg) and trans-3-ACPBPA (100 mg/kg) enhanced learning and memory in male Wistar rats; compared with vehicle there was a significant reduction in time for rats to find the platform in the Morris water maze task (p < 0.05; n = 10). As the physiological effects of cis- and trans-3-ACPBPA are similar to those reported for CGP36742, the memory and refractive effects of CGP36742 may be due in part to its GABA(C) activity.
authors.affiliation: Faculty of Pharmacy A15, The University of Sydney, Sydney, NSW 2006, Australia. maryc@pharm.usyd.edu.au
authors.forename: Mary
authors.initials: M
authors.lastname: Chebib
authors.forename: Tina
authors.initials: T
authors.lastname: Hinton
authors.forename: Katrina L
authors.initials: KL
authors.lastname: Schmid
authors.forename: Darren
authors.initials: D
authors.lastname: Brinkworth
authors.forename: Haohua
authors.initials: H
authors.lastname: Qian
authors.forename: Susana
authors.initials: S
authors.lastname: Matos
authors.forename: Hye-Lim
authors.initials: HL
authors.lastname: Kim
authors.forename: Heba
authors.initials: H
authors.lastname: Abdel-Halim
authors.forename: Rohan J
authors.initials: RJ
authors.lastname: Kumar
authors.forename: Graham A R
authors.initials: GA
authors.lastname: Johnston
authors.forename: Jane R
authors.initials: JR
authors.lastname: Hanrahan
mesh_terms: D000818:Animals; D002642:Chick Embryo; D004195:Disease Models, Animal; D018756:GABA Antagonists / Q000627:therapeutic use*; D006801:Humans; D007858:Learning / Q000187:drug effects* / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D009216:Myopia / Q000517:prevention & control*; D009943:Organophosphorus Compounds; D018408:Patch-Clamp Techniques; D010829:Physiological Phenomena; D051381:Rats; D018079:Receptors, GABA / Q000187:drug effects; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
chemical_list: D018756:GABA Antagonists; C087200:GABA-C receptor; D009943:Organophosphorus Compounds; D018079:Receptors, GABA; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; C079148:(3-aminopropyl)(n-butyl)phosphinic acid