Zinc-mediated inhibition of human α₁β₂ and α₁β₂γ_2S GABA_AR signalling in <i>Xenopus</i> oocytes.

<p>(A) Representative trace of the inhibition mediated 100 μM Zn²⁺ of the currents elicited by 10 μM GABA (EC₈₀) through the α₁β₂ GABA_AR. (B) Representative trace of the inhibition mediated 100 μM Zn²⁺ of the currents induced by 100 μM GABA (EC₈₀) through the α₁β₂γ_2S GABA_AR. (C) The degree of inhibition mediated by 100 μM Zn²⁺ of GABA EC₈₀-evoked currents in oocytes expressing α₁β₂ mean ± S.E.M.; 77 ± 6.3%; N = 7and α₁β₂γ_2S (mean ± S.E.M.; 4.7 ± 4.6%; N = 6) GABA_ARs.</p

Functional properties of GABA at six human GABA_ARs expressed in <i>Xenopus</i> oocytes.

<p>Concentration-response curves of GABA at the α₁β₂γ_2S (circle), α₂β₂γ_2S (square), α₃β₂γ_2S (triangle), α₅β₂γ_2S (inverted triangle), α₆β₂δ (diamond) and α₆β₂ (asterisk) GABA_ARs (means ± S.E.M.; N = 4–7).</p

Functional properties of GABA at the human α₁β₂γ_2S, α₂β₂γ_2S, α₃β₂γ_2S, α₅β₂γ_2S, α₆β₂δ and α₆β₂GABA_ARs expressed in <i>Xenopus</i> oocytes.

<p>The EC₅₀ values are given in μM with pEC₅₀ ± S.E.M. values in brackets, and the Hill slopes (n_H ± S.E.M.) and the numbers of experiments (N) are also given.</p

Comparison of the functional efficacies of clobazam, <i>N</i>-desmethylclobazam, and clonazepam at α_1,2,3,5β₂γ_2S GABA_ARs with those of diazepam and zolpidem.

<p>(A) Potentiation of the response elicited by GABA EC₂₀ by 3 μM diazepam in Xenopus oocytes injected with cRNAs encoding for α₁β₂γ_2S, α₂β₂γ_2S, α₃β₂γ_2S and α₅β₂γ_2S GABA_ARs in a subunit ratio of 1:1:1 (means ± S.E.M.; N = 2–4) (B) Potentiation of the response elicited by EC₂₀ GABA by 3 μM clobazam and 3 μM zolpidem in Xenopus oocytes injected with cRNAs encoding the α₂β₂γ_2S GABA_AR injected in a subunit ratio of 1:1:5 (means ± S.E.M.; N = 2).</p

. Functional properties of clobazam, <i>N</i>-desmethylclobazam and clonazepam at the human α₆β₂δ and α₆β₂ GABA_ARs expressed in <i>Xenopus</i> oocytes.

<p>(A) Representative traces for various concentrations of clobazam (top), <i>N</i>-desmethylclobazam (middle) and clonazepam (bottom) co-applied with GABA EC₂₀ to oocytes expressing the α₆β₂δ GABA_AR. The black bars represent applications of GABA EC₂₀ and of 300 M GABA that elicits maximal current through the receptor. The grey bars represent applications of various concentrations of clobazam, <i>N</i>-desmethylclobazam or clonazepam (a 30 s pre-incubation with the compound followed by co-application of the compound and GABA EC₂₀). (B) Concentration-response relationships for clobazam (top), <i>N</i>-desmethylclobazam (middle) and clonazepam (bottom) at the α₆β₂δ GABA_AR and for <i>N</i>-desmethylclobazam at the α₆β₂ GABA_AR (middle) in the presence of GABA EC₂₀ (means ± S.E.M.; N = 4–6).</p

Chemical structures of clobazam, <i>N</i>-desmethylclobazam and clonazepam.

<p>Chemical structures of clobazam, <i>N</i>-desmethylclobazam and clonazepam.</p

Semisynthetic Analogues of Toxiferine I and Their Pharmacological Properties at α7 nAChRs, Muscle-Type nAChRs, and the Allosteric Binding Site of Muscarinic M₂ Receptors

A new series of analogues of the calabash curare alkaloid toxiferine I was prepared and pharmacologically evaluated at α7 and muscle-type nAChRs and the allosteric site of muscarinic M₂ receptors. The new ligands differ from toxiferine I by the absence of one (<b>2a</b>–<b>c</b>) or two (<b>3a</b>–<b>c</b>) hydroxy groups, saturation of the exocyclic double bonds, and various N-substituents (methyl, allyl, 4-nitrobenzyl). At the muscle-type nAChRs, most ligands showed similar binding to the muscle relaxant alcuronium, indicating neuromuscular blocking activity, with the nonhydroxylated analogues <b>3b</b> (<i>K</i>_i = 75 nM) and <b>3c</b> (<i>K</i>_i = 82 nM) displaying the highest affinity. At α7 nAChRs, all ligands showed a moderate to low antagonistic effect, suggesting that the alcoholic functions are not necessary for antagonistic action. Compound <b>3c</b> exerted the highest preference for the muscle-type nAChRs (<i>K</i>_i = 82 nM) over α7 (IC₅₀ = 21 μM). As for the allosteric site of M₂ receptors, binding was found to be dependent on N-substitution rather than on the nature of the side chains. The most potent ligands were the <i>N</i>-allyl analogues <b>2b</b> and <b>3b</b> (EC_0.5,diss = 12 and 36 nM) and the <i>N</i>-nitrobenzyl derivatives <b>2c</b> and <b>3c</b> (EC_0.5,diss = 32 and 49 nM). The present findings should help delineate the structural requirements for activity at different types of AChRs and for the design of novel selective ligands

Changes in cortical network activity induced by 7–9 cumulatively increasing concentrations of the functionally selective δ-GABA_AR agonists THIP and Thio-THIP.

<p>The heat maps present statistically significant changes in 40 activity parameters relative to native activity (no drug, 100%) (Student’s paired t-test, p≤0.05). The concentration-response relationships for the drugs at 10 selected activity parameters are given as mean ± S.E.M. relative to native activity (no drug, 100%).</p

Changes in cortical network activity induced by 7–8 cumulatively increasing concentrations of THIP in the absence and in the presence of 300 nM, 1 μM or 3 μM DS2.

<p>The heat maps to the left of the vertical hatched line present statistically significant changes in 40 activity parameters relative to native activity (no drug, 100%) (Student’s paired t-test, p≤0.05). The concentration-response relationships for the drug combinations at 10 selected activity parameters are given as mean ± S.E.M. relative to native activity (no drug, 100%). The heat maps to the right of the vertical hatched line present statistically significant changes in the 40 activity parameters between the activity induced by a specific THIP concentration co-applied with 300 nM, 1 μM or 3 μM DS2 relative to the activity induced by that specific THIP concentration on its own (100%) (Student’s paired t-test, p≤0.05).</p

Novel Aza-analogous Ergoline Derived Scaffolds as Potent Serotonin 5‑HT₆ and Dopamine D₂ Receptor Ligands.

By introducing distal substituents on a tetracyclic scaffold resembling the ergoline structure, two series of analogues were achieved exhibiting subnanomolar receptor binding affinities for the dopamine D₂ and serotonin 5-HT₆ receptor subtype, respectively. While the 5-HT₆ ligands were antagonists, the D₂ ligands displayed intrinsic activities ranging from full agonism to partial agonism with low intrinsic activity. These structures could potentially be interesting for treatment of neurological diseases such as schizophrenia, Parkinson’s disease, and cognitive deficits