WAY-855 (3-amino-tricyclo[2.2.1.0(2.6)]heptane-1,3-dicarboxylic acid): a novel, EAAT2-preferring, nonsubstrate inhibitor of high-affinity glutamate uptake

1. The pharmacological profile of a novel glutamate transport inhibitor, WAY-855 (3-amino-tricyclo[2.2.1.0(2.6)]heptane-1,3-dicarboxylic acid), on the activity of the human forebrain glutamate transporters EAAT1, EAAT2 and EAAT3 expressed in stable mammalian cell lines and in Xenopus laevis oocytes is presented. 2. WAY-855 inhibited glutamate uptake mediated by all three subtypes in a concentration-dependent manner, with preferential inhibition of the CNS-predominant EAAT2 subtype in both cells and oocytes. IC(50) values for EAAT2 and EAAT3 inhibition in cells were 2.2 and 24.5 μM, respectively, while EAAT1 activity was inhibited by 50% at 100 μM (IC(50) values determined in oocytes were 1.3 μM (EAAT2), 52.5 μM (EAAT3) and 125.9 μM (EAAT1)). 3. Application of WAY-855 to EAAT-expressing oocytes failed to induce a transporter current, and the compound failed to exchange with accumulated [(3)H]D-aspartate in synaptosomes consistent with a nonsubstrate inhibitor. WAY-855 inhibited D-aspartate uptake into cortical synaptosomes by a competitive mechanism, and with similar potency to that observed for the cloned EAAT2. 4. WAY-855 failed to agonise or antagonise ionotropic glutamate receptors in cultured hippocampal neurones, or the human metabotropic glutamate receptor subtype 4 expressed in a stable cell line. 5. WAY-855 represents a novel structure in glutamate transporter pharmacology, and exploration of this structure might provide insights into the discrimination between EAAT2 and other EAAT subtypes

Potent Dihydroquinolinone Dopamine D2 Partial Agonist/Serotonin Reuptake Inhibitors for the Treatment of Schizophrenia

A dihydroquinolinone moiety was found to be a potent serotonin reuptake inhibitor pharmacophore when combined with certain amines. This fragment was coupled with selected D2 ligands to prepare a series of dual acting compounds with attractive in vitro profiles as dopamine D2 partial agonists and serotonin reuptake inhibitors. Structure-activity studies revealed that the linker plays a key role in contributing to D2 affinity, function, and SRI activity

Procognitive and neuroprotective activity of a novel alpha7 nicotinic acetylcholine receptor agonist for treatment of neurodegenerative and cognitive disorders

ABSTRACT The ␣7 nicotinic acetylcholine receptor (nAChR) is a promising target for treatment of cognitive dysfunction associated with Alzheimer's disease and schizophrenia. Here, we report the pharmacological properties of 5-morpholin-4-yl-pentanoic acid (4-pyridin-3-yl-phenyl)-amide [SEN12333 (WAY-317538)], a novel selective agonist of ␣7 nAChR. SEN12333 shows high affinity for the rat ␣7 receptor expressed in GH4C1 cells (K i ϭ 260 nM) and acts as full agonist in functional Ca 2ϩ flux studies (EC 50 ϭ 1.6 M). In whole-cell patch-clamp recordings, SEN12333 activated peak currents and maximal total charges similar to acetylcholine (EC 50 ϭ 12 M). The compound did not show agonist activity at other nicotinic receptors tested and acted as a weak antagonist at ␣3-containing receptors. SEN12333 treatment (3 mg/kg i.p.) improved episodic memory in a novel object recognition task in rats in conditions of spontaneous forgetting as well as cognitive disruptions induced via glutamatergic [5H-dibenzo[a,d]cyclohepten-5,10-imine (dizocilpine maleate); MK-801] or cholinergic (scopolamine) mechanisms. This improvement was blocked by the ␣7-selective antagonist methyllycaconitine, indicating that it is mediated by ␣7 activation. SEN12333 also prevented a scopolamine-induced deficit in a passive avoidance task. In models targeting other cognitive domains, including attention and perceptual processing, SEN12333 normalized the apomorphine-induced deficit of prepulse inhibition. Neuroprotection of SEN12333 was demonstrated in quisqualate-lesioned animals in which treatment with SEN12333 (3 mg/kg/day i.p.) resulted in a significant protection of choline acetyltransferase-positive neurons in the lesioned hemisphere. Cumulatively, our results demonstrate that the novel ␣7 nAChR agonist SEN12333 has procognitive and neuroprotective properties, further demonstrating utility of ␣7 agonists for treatment of neurodegenerative and cognitive disorders. The family of nicotinic acetylcholine receptors, which comprises 16 different subunits in human (␣1-7, ␣9 -10, ␤1-4, ␦, ε, and ␥) that can form many functional homo-and heteropentameric receptor ion channel combinations, contributes to cholinergic neurotransmission in the nervous system and at the neuromuscular junction. The ␣7 nicotinic acetylcholine receptors (nAChRs) are rapidly desensitizing ligand-gated ion channels that are abundantly expressed in the cerebral cortex and the hippocampus, a limbic structure intimately linked to attention processing and memory formatio

Tetrahydrocarbazole-Based Serotonin Reuptake Inhibitor/Dopamine D2 Partial Agonists for the Potential Treatment of Schizophrenia

A 5-fluoro-tetrahydrocarbazole serotonin reuptake inhibitor (SRI) building block was combined with a variety of linkers and dopamine D2 receptor ligands in an attempt to identify potent D2 partial agonist/SRI molecules for treatment of schizophrenia. This approach has the potential to treat a broader range of symptoms compared to existing therapies. Selected compounds in this series demonstrate high affinity for both targets and D2 partial agonism in cell-based and in vivo assays