Enantiopure Cyclopropane-Bearing Pyridyldiazabicyclo[3.3.0]Octanes As Selective α4β2-Nachr Ligands

We report the synthesis and characterization of a series of enantiopure 5-cyclopropane-bearing pyridyldiazabicyclo[3.3.0]octanes that display low nanomolar binding affinities and act as functional agonists at α4β2-nicotinic acetylcholine receptor (nAChR) subtype. Structure-activity relationship studies revealed that incorporation of a cyclopropane-containing side chain at the 5-position of the pyridine ring provides ligands with improved subtype selectivity for nAChR β2 subunit-containing nAChR subtypes (β2∗-nAChRs) over α4∗-nAChRs compared to the parent compound 4. Compound 15 exhibited subnanomolar binding affinity for α4β2-and α4β2∗-nAChRs with negligible interaction. Functional assays confirm selectivity for α4β2-nAChRs. Furthermore, using the SmartCube assay system, this ligand showed antidepressant, anxiolytic, and antipsychotic features, while mouse forced-swim assay further confirm the antidepressant-like property of 15

Discovery Of Highly Potent And Selective α4β2-Nicotinic Acetylcholine Receptor (Nachr) Partial Agonists Containing An Isoxazolylpyridine Ether Scaffold That Demonstrate Antidepressant-Like Activity. Part II

In our continued efforts to develop α4β2-nicotinic acetylcholine receptor (nAChR) partial agonists as novel antidepressants having a unique mechanism of action, structure-activity relationship (SAR) exploration of certain isoxazolylpyridine ethers is presented. In particular, modifications to both the azetidine ring present in the starting structure 4 and its metabolically liable hydroxyl side chain substituent have been explored to improve compound druggability. The pharmacological characterization of all new compounds has been carried out using [ 3 H]epibatidine binding studies together with functional assays based on 86 Rb + ion flux measurements. We found that the deletion of the metabolically liable hydroxyl group or its replacement by a fluoromethyl group not only maintained potency and selectivity but also resulted in compounds showing antidepressant-like properties in the mouse forced swim test. These isoxazolylpyridine ethers appear to represent promising lead candidates in the design of innovative chemical tools containing reporter groups for imaging purposes and of possible therapeutics. © 2012 American Chemical Society

Identification Of Novel α4β2-Nicotinic Acetylcholine Receptor (Nachr) Agonists Based On An Isoxazole Ether Scaffold That Demonstrate Antidepressant-Like Activity

There is considerable evidence to support the hypothesis that the blockade of nAChR is responsible for the antidepressant action of nicotinic ligands. The nicotinic acetylcholine receptor (nAChR) antagonist, mecamylamine, has been shown to be an effective add-on in patients that do not respond to selective serotonin reuptake inhibitors. This suggests that nAChR ligands may address an unmet clinical need by providing relief from depressive symptoms in refractory patients. In this study, a new series of nAChR ligands based on an isoxazole-ether scaffold have been designed and synthesized for binding and functional assays. Preliminary structure-activity relationship (SAR) efforts identified a lead compound 43, which possesses potent antidepressant-like activity (1 mg/kg, IP; 5 mg/kg, PO) in the classical mouse forced swim test. Early stage absorption, distribution, metabolism, excretion, and toxicity (ADME-Tox) studies also suggested favorable drug-like properties, and broad screening toward other common neurotransmitter receptors indicated that compound 43 is highly selective for nAChRs over the other 45 neurotransmitter receptors and transporters tested. © 2011 American Chemical Society

Discovery Of Isoxazole Analogues Of Sazetidine-A As Selective α4β2-Nicotinic Acetylcholine Receptor Partial Agonists For The Treatment Of Depression

Depression, a common neurological condition, is one of the leading causes of disability and suicide worldwide. Standard treatment, targeting monoamine transporters selective for the neurotransmitters serotonin and noradrenaline, is not able to help many patients that are poor responders. This study advances the development of sazetidine-A analogues that interact with α4β2 nicotinic acetylcholine receptors (nAChRs) as partial agonists and that possess favorable antidepressant profiles. The resulting compounds that are highly selective for the α4β2 subtype of nAChR over α3β4-nAChRs are partial agonists at the α4β2 subtype and have excellent antidepressant behavioral profiles as measured by the mouse forced swim test. Preliminary absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies for one promising ligand revealed an excellent plasma protein binding (PPB) profile, low CYP450-related metabolism, and low cardiovascular toxicity, suggesting it is a promising lead as well as a drug candidate to be advanced through the drug discovery pipeline. © 2011 American Chemical Society

The Potent And Selective α4β2*/α6*-Nicotinic Acetylcholine Receptor Partial Agonist 2-[5-[5-((S)Azetidin-2-Ylmethoxy)-3-Pyridinyl]-3-Isoxazolyl]Ethanol Demonstrates Antidepressive-Like Behavior In Animal Models And A Favorable Adme-Tox Profile

Preclinical and clinical studies demonstrated that the inhibition of cholinergic supersensitivity through nicotinic antagonists and partial agonists can be used successfully to treat depressed patients, especially those who are poor responders to selective serotonin reuptake inhibitors (SSRIs). In our effort to develop novel antidepressant drugs, LF-3-88 was identified as a potent nicotinic acetylcholine receptor (nAChR) partial agonist with subnanomolar to nanomolar affinities for β2-containing nAChRs (α2β2, α3β2, α4β2, and α4β2*) and superior selectivity away from α3β4 − (K i  \u3e 10 4  nmol/L) and α7-nAChRs (K i  \u3e 10 4  nmol/L) as well as 51 other central nervous system (CNS)-related neurotransmitter receptors and transporters. Functional activities at different nAChR subtypes were characterized utilizing 86 Rb + ion efflux assays, two-electrode voltage-clamp (TEVC) recording in oocytes, and whole-cell current recording measurements. In mouse models, administration of LF-3-88 resulted in antidepressive-like behavioral signatures 15 min post injection in the SmartCube ® test (5 and 10 mg/kg, i.p.; about 45-min session), decreased immobility in the forced swim test (1–3 mg/kg, i.p.; 1–10 mg/kg, p.o.; 30 min pretreatment, 6-min trial), and decreased latency to approach food in the novelty-suppressed feeding test after 29 days chronic administration once daily (5 mg/kg but not 10 mg/kg, p.o.; 15-min trial). In addition, LF-3-88 exhibited a favorable profile in pharmacokinetic/ADME-Tox (absorption, distribution, metabolism, excretion, and toxicity) assays. This compound was also shown to cause no mortality in wild-type Balb/CJ mice when tested at 300 mg/kg. These results further support the potential of potent and selective nicotinic partial agonists for use in the treatment of depression

Thiolutin is a zinc chelator that inhibits the Rpn11 and other JAMM metalloproteases

Thiolutin is a disulfide-containing antibiotic and anti-angiogenic compound produced by Streptomyces. Its biological targets are not known. We show that reduced thiolutin is a zinc chelator that inhibits the JAB1/MPN/Mov34 (JAMM) domain–containing metalloprotease Rpn11, a deubiquitinating enzyme of the 19S proteasome. Thiolutin also inhibits the JAMM metalloproteases Csn5, the deneddylase of the COP9 signalosome; AMSH, which regulates ubiquitin-dependent sorting of cell-surface receptors; and BRCC36, a K63-specific deubiquitinase of the BRCC36-containing isopeptidase complex and the BRCA1–BRCA2-containing complex. We provide evidence that other dithiolopyrrolones also function as inhibitors of JAMM metalloproteases

Pharmacology of Temporal Cognition in Two Mouse Strains

Behavioral and pharmacological testing in mice has been revamped following the development of new tools for the manipulation of genetic information. We present the results from the peak procedure, an operant test that assesses the capacity to perceive, remember, and act upon temporal information. We studied the basic timing abilities in two different strains of mice, the C57Bl/6J and C3H/HeJ, and their response to psychoactive substances. Scopolamine and high doses of d-amphetamine disrupted performance by increasing response variability. The effect of d-amphetamine was particularly clear in C3H mice. Whereas scopolamine did not seem to affect the location of the response, the effect of a low dose of d-amphetamine, a leftward shift, was consistent with the hypothesis that it accelerates the internal time keeping mechanism. Physostigmine alone improved performance by reducing variability between trials without affecting the response location. Pretreatment with physostigmine partially blocked the deleterious effects of scopolamine. Methylphenidate did not have major effects on timing behavior in C57 but in the highest dose shifted the response of C3H mice to the left. The higher sensitivity of the C3H strain to the effects of d-amphetamine and methylphenidate support its value as an animal model of attention deficit disorder. The performance of mice in this temporal task was comparable to that observed in rats and pigeons, and seemed exquisitely sensitive to pharmacological manipulation

Effect of the rd1 mutation on motor performance in R6/2 and wild type mice

Homozygosis for the rd1 mutation in the Pbe6b gene results in the loss of the rod beta-subunit of the cyclic GMP phosphodiesterase and, eventually, of all rod and cone photoreceptors. The R6/2 mouse line is a widely used model of Huntington’s disease (HD). The original line was made available on a mixed background obtained by crossing, via ovarian transplant, female R6/2 (on a B6CBA mixed background) with male B6CBAF1/J mice. As the CBA/J strain used in the US is homozygous for the rd1 mutation and the breeding scheme does not ensure heterozygosis for the mutation, a significant percentage of the offspring on this mixed background is expected to be homozygous for the rd1 mutation. We investigate here the effect of rd1 homozygosis on motor function and examined the effects of the mutation on the R6/2 phenotype. Homozygosis for the rd1 mutation resulted in increased activity in the open field test and reduced rotarod test performance. In addition, rd1 mutation absence or heterozygosis reduced the differences between the R6/2 and the WT mice. Our recommendation for the neurodegeneration field, and for all mouse studies in general, is to carefully control homozygosis for retinal degeneration mutation, even when using tests of motor function