Functional profile of a novel modulator of serotonin, dopamine, and glutamate neurotransmission.

RATIONALE: Schizophrenia remains among the most prevalent neuropsychiatric disorders, and current treatment options are accompanied by unwanted side effects. New treatments that better address core features of the disease with minimal side effects are needed. OBJECTIVES: As a new therapeutic approach, 1-(4-fluoro-phenyl)-4-((6bR, 10aS)-3-methyl-2,3,6b,9,10,10a-hexahydro-1H,7H-pyrido[3',4':4,5]pyrrolo[1,2,3-de]quinoxalin-8-yl)-butan-1-one (ITI-007) is currently in human clinical trials for the treatment of schizophrenia. Here, we characterize the preclinical functional activity of ITI-007. RESULTS: ITI-007 is a potent 5-HT2A receptor ligand (K i = 0.5 nM) with strong affinity for dopamine (DA) D2 receptors (K i = 32 nM) and the serotonin transporter (SERT) (K i = 62 nM) but negligible binding to receptors (e.g., H1 histaminergic, 5-HT2C, and muscarinic) associated with cognitive and metabolic side effects of antipsychotic drugs. In vivo it is a 5-HT2A antagonist, blocking (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI)-induced headtwitch in mice with an inhibitory dose 50 (ID50) = 0.09 mg/kg, per oral (p.o.), and has dual properties at D2 receptors, acting as a postsynaptic D2 receptor antagonist to block D-amphetamine hydrochloride (D-AMPH) hyperlocomotion (ID50 = 0.95 mg/kg, p.o.), yet acting as a partial agonist at presynaptic striatal D2 receptors in assays measuring striatal DA neurotransmission. Further, in microdialysis studies, this compound significantly and preferentially enhances mesocortical DA release. At doses relevant for antipsychotic activity in rodents, ITI-007 has no demonstrable cataleptogenic activity. ITI-007 indirectly modulates glutamatergic neurotransmission by increasing phosphorylation of GluN2B-type N-methyl-D-aspartate (NMDA) receptors and preferentially increases phosphorylation of glycogen synthase kinase 3ß (GSK-3ß) in mesolimbic/mesocortical dopamine systems. CONCLUSION: The combination of in vitro and in vivo activities of this compound support its development for the treatment of schizophrenia and other psychiatric and neurologic disorders.

Discovery of a tetracyclic quinoxaline derivative as a potent and orally active multifunctional drug candidate for the treatment of neuropsychiatric and neurological disorders.

We report the synthesis and structure-activity relationships of a class of tetracyclic butyrophenones that exhibit potent binding affinities to serotonin 5-HT(2A) and dopamine D2 receptors. This work has led to the discovery of 4-((6bR,10aS)-3-methyl-2,3,6b,9,10,10a-hexahydro-1H,7H-pyrido[3',4':4,5]pyrrolo[1,2,3-de]quinoxalin-8-yl)-1-(4-fluorophenyl)-butan-1-one 4-methylbenzenesulfonate (ITI-007), which is a potent 5-HT(2A) antagonist, postsynaptic D2 antagonist, and inhibitor of serotonin transporter. This multifunctional drug candidate is orally bioavailable and exhibits good antipsychotic efficacy in vivo. Currently, this investigational new drug is under clinical development for the treatment of neuropsychiatric and neurological disorders.

Discovery of novel alpha7 nicotinic receptor antagonists.

Two distinct families of small molecules were discovered as novel alpha7 nicotinic acetylcholine receptor (nAChR) antagonists by pharmacophore-based virtual screening. These novel antagonists exhibited selectivity for the neuronal alpha7 subtype over other nAChRs and good brain penetration. Neuroprotection was demonstrated by representative compounds 7i and 8 in a mouse seizure-like behavior model induced by the nerve agent diisopropylfluorophosphate (DFP). These novel nAChR antagonists have potential use as antidote for organophosphorus nerve agent intoxication.

Nerve agent exposure elicits site-specific changes in protein phosphorylation in mouse brain.

Organophosphorus (OP) compounds cause toxic symptoms, including convulsions, coma, and death, as the result of irreversible inhibition of acetylcholinesterase (AChE). The development of effective treatments to block these effects and attenuate long-term cognitive and motor disabilities that result from OP intoxication is hampered by a limited understanding of the CNS pathways responsible for these actions. We employed a candidate method (called CNSProfile) to identify changes in the phosphorylation state of key neuronal phosphoproteins evoked by the OP compound, diisopropyl fluorophosphate (DFP). Focused microwave fixation was used to preserve the phosphorylation state of phosphoproteins in brains of DFP-treated mice; hippocampus and striatum were analyzed by immunoblotting with a panel of phospho-specific antibodies. DFP exposure elicited comparable effects on phosphorylation of brain phosphoproteins in both C57BL/6 and FVB mice. DFP treatment significantly altered phosphorylation at regulatory residues on glutamate receptors, including Serine897 (S897) of the NR1 NMDA receptor. NR1 phosphorylation was bi-directionally regulated after DFP in striatum versus hippocampus. NR1 phosphorylation was reduced in striatum, but elevated in hippocampus, compared with controls. DARPP-32 phosphorylation in striatum was selectively increased at the Cdk5 kinase substrate, Threonine75 (T75). Phencynonate hydrochloride, a muscarinic cholinergic antagonist, prevented seizure-like behaviors and the observed changes in phosphorylation induced by DFP. The data reveal region-specific effects of nerve agent exposure on intracellular signaling pathways that correlate with seizure-like behavior and which are reversed by the muscarinic receptor blockade. This approach identifies specific targets for nerve agents, including substrates for Cdk5 kinase, which may be the basis for new anti-convulsant therapies.

Magic Angle Spinning NMR for Reaction Monitoring and Structure Determination of Molecules Attached to Multipin Crowns.

The first example of magic angle spinning NMR on crowns has been demonstrated. The ability to monitor a reaction on a crown and to confirm the structure of the reaction product directly on the crown without resorting to chemical cleavage should greatly enhance the utility of this convenient format for combinatorial chemistry.