A novel positive allosteric modulator of the GABA(A) receptor: the action of (+)-ROD188.
ABSTRACT (+)-ROD188 was synthesized in the search for novel ligands of the GABA binding site. It shares some structural similarity with bicuculline. (+)-ROD188 failed to displace [(3)H]-muscimol in binding studies and failed to induce channel opening in recombinant rat alpha1beta2gamma2 GABA(A) receptors functionally expressed in Xenopus oocytes. (+)-ROD188 allosterically stimulated GABA induced currents. Displacement of [(3)H]-Ro15-1788 indicated a low affinity action at the benzodiazepine binding site. In functional studies, stimulation by (+)-ROD188 was little sensitive to the presence of 1 microM of the benzodiazepine antagonist Ro 15-1788, and (+)-ROD188 also stimulated currents mediated by alpha1beta2, indicating a major mechanism of action different from that of benzodiazepines. Allosteric stimulation by (+)-ROD188 was similar in alpha1beta2N265S as in unmutated alpha1beta2, while that by loreclezole was strongly reduced. (+)-ROD188 also strongly stimulated currents elicited by either pentobarbital or 5alpha-pregnan-3alpha-ol-20-one (3alpha-OH-DHP), in line with a mode of action different from that of barbiturates or neurosteroids as channel agonists. Stimulation by (+)-ROD188 was largest in alpha6beta2gamma2 (alpha6beta2gamma2>alpha1beta2gamma2=alpha5beta2gamma2++ +>alpha2beta2ga mma2= alpha3beta2gamma2), indicating a unique subunit isoform specificity. Miniature inhibitory postsynaptic currents (mIPSC) in cultures of rat hippocampal neurons, caused by spontaneous release of GABA showed a prolonged decay time in the presence of 30 microM (+)-ROD188, indicating an enhanced synaptic inhibitory transmission.
Full-textDOI: · Available from: Werner Sieghart, May 15, 2015
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ABSTRACT: 1,4-Addition of benzylamine to 2(5H)-furanone followed by dialkylation of the 3-position with allylbromide gave (+/-)-4-benzyl-3,3-diallyl-2(3H)-furanone (8), which served as the intermediate for the synthesis of various N-substituted 4-amino-3,3-dipropyl-2(3H)-furanones (+/-)-9a-1. The compounds were evaluated for their capacity to potentiate or inhibit GABA-evoked currents in Xenopus laevis oocytes expressing recombinant alpha1beta2gamma2 GABA(A) receptors. The benzyl, ethyl., and allyl carbamates ((R)-9a (100 muM), (+/-)-9b (100 muM), (+/-)-9c (200 muM)) stimulated GABA currents by 279 +/- 47%, 426 +/- 8%. and 765 +/- 61%, respectively, while the phenylcarboxamide (+/-)-9f (200 muM) stimulated currents by 420 +/- 33%. Concentration-response studies showed that compound 9c was approximately twice as potent in stimulating GABA currents as alpha-EMTBL (2), the most potent 3,3-dialkylbutyrolactone known to date. On the other hand, the N-sulfonyl analogues were much less active or even inhibited GABA-evoked currents. In vitro radioligand displacement studies on rat brain membranes showed that these compounds did not bind to the benzodiazepine or GABA recognition sites of the GABAA receptor. However, these compounds generally weakly displaced [S-35]-TBPS (approximately 50% displacement at 100 muM), though potencies did not correlate with GABA current potentiation. Results obtained with 0 1 and mutant alpha1beta2N265S receptors, which compared to alpha1/beta2 receptors are both much less sensitive to current stimulation produced by the anticonvulsant loreclezole, suggest that at least some of these aminobutyrolactones, (e.g., 9a, 9c), and interestingly also alpha-EMTBL, share stimulatory properties with loreclezole.Journal of Medicinal Chemistry 06/2002; 45(13):2824-2831. DOI:10.1021/jm011082k · 5.48 Impact Factor
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ABSTRACT: GABAA receptors are the major inhibitory neurotransmitter receptors in the mammalian brain and the target of many clinically important drugs interacting with different binding sites. Recently, we demonstrated that CGS 9895 (2-(4-methoxyphenyl)-2H-pyrazolo[4,3- c]quinolin-3(5H)-one) acts as a null modulator (antagonist) at the high affinity benzodiazepine binding site, but in addition elicits a strong enhancement of GABAinduced currents via a novel drug binding site at the extracellular a+b− interface. Here, we investigated 32 structural analogues of CGS 9895 for their ability to mediate their effects via the a1+b3- interface of GABAA receptors.British Journal of Pharmacology 05/2013; 169(2). DOI:10.1111/bph.12151 · 4.99 Impact Factor
Drugs of the Future 12/2001; 26(12). DOI:10.1358/dof.2001.026.12.639536 · 0.25 Impact Factor