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 formation (Gotti et al., 2006). In the hippocampus, ␣7 nAChRs are present in interneurons and glutamatergic pyramidal neurons, in which they are localized presynaptically in nerve terminals and postsynaptically in dendritic spines and soma. In line with their localization, ␣7 nAChRs modulate neurotransmitter release and are responsible for direct fast excitatory neuroArticle, publication date, and citation information can be found at

Nicotinic acetylcholine receptors (nAChR) have been strongly implicated as therapeutic targets for treating cognitive deficits in disorders such as schizophrenia and Alzheimer's disease (AD). In particular alpha7 and alpha4beta2 subtype-selective nAChR agonists and partial agonists have been developed as potential candidates for the treatment of schizophrenia, cognitive disorders (including Alzheimer's disease), and inflammation. Further development of positive allosteric modulators and antagonists were also recently reported in the literature. In this review we will cover recent developments focused on the above mentioned nAChR subtypes, starting from the most advanced clinical candidate followed by an overview of literature compounds where potency, selectivity, central nervous system access, pharmacological activity and pharmacokinetic properties are disclosed.

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Alpha-7 nicotinic acetylcholine receptor (alpha7 nAChR) agonists are promising therapeutic candidates for the treatment of cognitive impairment. We report a series of novel, potent small molecule agonists (4-18) of the alpha7 nAChR deriving from our continuing efforts in the areas of Alzheimer's disease and schizophrenia. One of the compounds of the series containing a urea moiety (16) was further shown to be a selective agonist of the alpha7 nAChR with excellent in vitro and in vivo profiles, brain penetration, and oral bioavailability and demonstrated in vivo efficacy in multiple behavioral cognition models. Structural modifications leading to the improved selectivity profile and the biological evaluation of this series of compounds are discussed.

Alpha-7 nicotinic acetylcholine receptors (α7 nAChR) are implicated in the modulation of many cognitive functions such as attention, working memory, and episodic memory. For this reason, α7 nAChR agonists represent promising therapeutic candidates for the treatment of cognitive impairment associated with Alzheimer's disease (AD) and schizophrenia. A medicinal chemistry effort, around our previously reported chemical series, permitted the discovery of a novel class of α7 nAChR agonists with improved selectivity, in particular against the α3 receptor subtype and better ADME profile. The exploration of this series led to the identification of 5-(4-acetyl[1,4]diazepan-1-yl)pentanoic acid [5-(4-methoxyphenyl)-1H-pyrazol-3-yl] amide (25, SEN15924, WAY-361789), a novel, full agonist of the α7 nAChR that was evaluated in vitro and in vivo. Compound 25 proved to be potent and selective, and it demonstrated a fair pharmacokinetic profile accompanied by efficacy in rodent behavioral cognition models (novel object recognition and auditory sensory gating).