Tine B. Stensbøl

CNVs conferring risk of autism or schizophrenia affect cognition in controls

In a small fraction of patients with schizophrenia or autism, alleles of copy-number variants (CNVs) in their genomes are probably the strongest factors contributing to the pathogenesis of the disease. These CNVs may provide an entry point for investigations into the mechanisms of brain function and dysfunction alike. They are not fully penetrant and offer an opportunity to study their effects separate from that of manifest disease. Here we show in an Icelandic sample that a few of the CNVs clearly alter fecundity (measured as the number of children by age 45). Furthermore, we use various tests of cognitive function to demonstrate that control subjects carrying the CNVs perform at a level that is between that of schizophrenia patients and population controls. The CNVs do not all affect the same cognitive domains, hence the cognitive deficits that drive or accompany the pathogenesis vary from one CNV to another. Controls carrying the chromosome 15q11.2 deletion between breakpoints 1 and 2 (15q11.2(BP1-BP2) deletion) have a history of dyslexia and dyscalculia, even after adjusting for IQ in the analysis, and the CNV only confers modest effects on other cognitive traits. The 15q11.2(BP1-BP2) deletion affects brain structure in a pattern consistent with both that observed during first-episode psychosis in schizophrenia and that of structural correlates in dyslexia.

Discovery of 1-[2-(2,4-dimethylphenylsulfanyl)phenyl]piperazine (Lu AA21004): a novel multimodal compound for the treatment of major depressive disorder.

The synthesis and structure-activity relationship of a novel series of compounds with combined effects on 5-HT(3A) and 5-HT(1A) receptors and on the serotonin (5-HT) transporter (SERT) are described. Compound 5m (Lu AA21004) was the lead compound, displaying high affinity for recombinant human 5-HT(1A) (K(i) = 15 nM), 5-HT(1B) (K(i) = 33 nM), 5-HT(3A) (K(i) = 3.7 nM), 5-HT(7) (K(i) = 19 nM), and noradrenergic β(1) (K(i) = 46 nM) receptors, and SERT (K(i) = 1.6 nM). Compound 5m displayed antagonistic properties at 5-HT(3A) and 5-HT(7) receptors, partial agonist properties at 5-HT(1B) receptors, agonistic properties at 5-HT(1A) receptors, and potent inhibition of SERT. In conscious rats, 5m significantly increased extracellular 5-HT levels in the brain after acute and 3 days of treatment. Following the 3-day treatment (5 or 10 (mg/kg)/day) SERT occupancies were only 43% and 57%, respectively. These characteristics indicate that 5m is a novel multimodal serotonergic compound, and 5m is currently in clinical development for major depressive disorder.

Pharmacological effects of Lu AA21004: a novel multimodal compound for the treatment of major depressive disorder.

1-[2-(2,4-Dimethylphenyl-sulfanyl)-phenyl]-piperazine (Lu AA21004) is a human (h) serotonin (5-HT)3A receptor antagonist (Ki = 3.7 nM), h5-HT7 receptor antagonist (Ki = 19 nM), h5-HT1B receptor partial agonist (Ki = 33 nM), h5-HT1A receptor agonist (Ki = 15 nM), and a human 5-HT transporter (SERT) inhibitor (Ki = 1.6 nM) (J Med Chem 54:3206–3221, 2011). Here, we confirm that Lu AA21004 is a partial h5-HT1B receptor agonist [EC50 = 460 nM, intrinsic activity = 22%] using a whole-cell cAMP-based assay and demonstrate that Lu AA21004 is a rat (r) 5-HT7 receptor antagonist (Ki = 200 nM and IC50 = 2080 nM). In vivo, Lu AA21004 occupies the r5-HT1B receptor and rSERT (ED50 = 3.2 and 0.4 mg/kg, respectively) after subcutaneous administration and is a 5-HT3 receptor antagonist in the Bezold-Jarisch reflex assay (ED50 = 0.11 mg/kg s.c.). In rat microdialysis experiments, Lu AA21004 (2.5–10.0 mg/kg s.c.) increased extracellular 5-HT, dopamine, and noradrenaline in the medial prefrontal cortex and ventral hippocampus. Lu AA21004 (5 mg/kg per day for 3 days; minipump subcutaneously), corresponding to 41% rSERT occupancy, significantly increased extracellular 5-HT in the ventral hippocampus. Furthermore, the 5-HT3 receptor antagonist, ondansetron, potentiated the increase in extracellular levels of 5-HT induced by citalopram. Lu AA21004 has antidepressant- and anxiolytic-like effects in the rat forced swim (Flinders Sensitive Line) and social interaction and conditioned fear tests (minimal effective doses: 7.8, 2.0, and 3.9 mg/kg). In conclusion, Lu AA21004 mediates its pharmacological effects via two pharmacological modalities: SERT inhibition and 5-HT receptor modulation. In vivo, this results in enhanced release of several neurotransmitters and antidepressant- and anxiolytic-like profiles at doses for which targets in addition to the SERT are occupied. The multimodal activity profile of Lu AA21004 is distinct from that of current antidepressants.

Brexpiprazole I: In Vitro and In Vivo Characterization of a Novel Serotonin-Dopamine Activity Modulator

Brexpiprazole (OPC-34712, 7-{4-[4-(1-benzothiophen-4-yl)piperazin-1-yl]butoxy}quinolin-2(1H)-one) is a novel drug candidate in clinical development for psychiatric disorders with high affinity for serotonin, dopamine, and noradrenaline receptors. In particular, it bound with high affinity (Ki < 1 nM) to human serotonin 1A (h5-HT1A)-, h5-HT2A-, long form of human D2 (hD2L)-, hα1B-, and hα2C-adrenergic receptors. It displayed partial agonism at h5-HT1A and hD2 receptors in cloned receptor systems and potent antagonism of h5-HT2A receptors and hα1B/2C-adrenoceptors. Brexpiprazole also had affinity (Ki < 5 nM) for hD3-, h5-HT2B-, h5-HT7-, hα1A-, and hα1D-adrenergic receptors, moderate affinity for hH1 (Ki = 19 nM), and low affinity for hM1 receptors (Ki > 1000 nM). Brexpiprazole potently bound to rat 5-HT2A and D2 receptors in vivo, and ex vivo binding studies further confirmed high 5-HT1A receptor binding potency. Brexpiprazole inhibited DOI (2,5-dimethoxy-4-iodoamphetamine)-induced head twitches in rats, suggestive of 5-HT2A antagonism. Furthermore, in vivo D2 partial agonist activity of brexpiprazole was confirmed by its inhibitory effect on reserpine-induced DOPA accumulation in rats. In rat microdialysis studies, brexpiprazole slightly reduced extracellular dopamine in nucleus accumbens but not in prefrontal cortex, whereas moderate increases of the dopamine metabolites, homovanillic acid and DOPAC (3,4-dihydroxy-phenyl-acetic acid), in these areas also suggested in vivo D2 partial agonist activity. In particular, based on a lower intrinsic activity at D2 receptors and higher binding affinities for 5-HT1A/2A receptors than aripiprazole, brexpiprazole would have a favorable antipsychotic potential without D2 receptor agonist- and antagonist-related adverse effects. In conclusion, brexpiprazole is a serotonin-dopamine activity modulator with a unique pharmacology, which may offer novel treatment options across a broad spectrum of central nervous system disorders.

Genetic predictors of response to serotonergic and noradrenergic antidepressants in major depressive disorder: a genome-wide analysis of individual-level data and a meta-analysis

Testing whether genetic information could inform the selection of the best drug for patients with depression, Rudolf Uher and colleagues searched for genetic variants that could predict clinically meaningful responses to two major groups of antidepressants.

Discovery of the First Selective Inhibitor of Excitatory Amino Acid Transporter Subtype 1

The discovery of the first class of subtype-selective inhibitors of the human excitatory amino acid transporter subtype 1 (EAAT1) and its rat orthologue GLAST is reported. An opening structure-activity relationship of 25 analogues is presented that addresses the influence of substitutions at the 4- and 7-positions of the parental skeleton 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile. The most potent analogue 1o displays high nanomolar inhibitory activity at EAAT1 and a >400-fold selectivity over EAAT2 and EAAT3, making it a highly valuable pharmacological tool.

Resolution, absolute stereochemistry and molecular pharmacology of the enantiomers of ATPA.

(RS)-2-Amino-3-(5-tert-butyl-3-hydroxy-4-isoxazolyl)propionic acid (ATPA), an analogue of (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA). has previously been shown to be a relatively weak AMPA receptor agonist and a very potent agonist at the GluR5 subtype of kainic acid-preferring (S)-glutamic acid ((S)-Glu) receptors. We report here the separation of (+)- and (-)-ATPA, obtained at high enantiomeric purity (enantiomeric excess values of 99.8% and > 99.8%, respectively) using chiral chromatography, and the unequivocal assignment of the stereochemistry of (S)-(+)-ATPA and (R)-(-)-ATPA. (S)- and (R)-ATPA were characterized in receptor binding studies using rat brain membranes, and electrophysiologically using the rat cortical wedge preparation and cloned AMPA-preferring (GluR1, GluR3, and GluR4) and kainic acid-preferring (GluR5, GluR6, and GluR6 + KA2) receptors expressed in Xenopus oocytes. In the cortical wedge, (S)-ATPA showed AMPA receptor agonist effects (EC50 = 23 microM) approximately twice as potent as those of ATPA. (R)-ATPA antagonized depolarizations induced by AMPA (Ki = 253 microM) and by (S)-ATPA (Ki = 376 microM), and (R)-ATPA antagonized the biphasic depolarizing effects induced by kainic acid (Ki = 301 microM and 1115 microM). At cloned AMPA receptors, (S)-ATPA showed agonist effects at GluR3 and GluR4 with EC50 values of approximately 8 microM and at GluR1 (EC50 = 22 microM), producing maximal steady state currents only 5.4-33% of those evoked by kainic acid. (R)-ATPA antagonized currents evoked by kainic acid at cloned AMPA receptor subtypes with Ki values of 33-75 microM. (S)-ATPA produced potent agonist effects at GluR5 (EC50 = 0.48 microM). Due to desensitization of GluR5 receptors, which could not be fully prevented by treatment with concanavalin A, (S)-ATPA-induced agonist effects were normalized to those of kainic acid. Under these circumstances, maximal currents produced by (S)-ATPA and kainic acid were not significantly different. (R)-ATPA did not attenuate currents produced by kainic acid at GluR5, and neither (S)- nor (R)-ATPA showed significant effects at GluR6. (S)-ATPA as well as AMPA showed weak agonist effects at heteromeric GluR6 + KA2 receptors, whereas (R)-ATPA was inactive. Thus, (S)- and (R)-ATPA may be useful tools for mechanistic studies of ionotropic non-NMDA (S)-Glu receptors, and lead structures for the design of new subtype-selective ligands for such receptors.

Three-Dimensional Structure of the Ligand-Binding Core of GluR2 in Complex with the Agonist (S)-ATPA: Implications for Receptor Subunit Selectivity.

Two X-ray structures of the GluR2 ligand-binding core in complex with (S)-2-amino-3-(5-tert-butyl-3-hydroxy-4-isoxazolyl)propionic acid ((S)-ATPA) have been determined with and without Zn(2+) ions. (S)-ATPA induces a domain closure of ca. 21 degrees compared to the apo form. The tert-butyl moiety of (S)-ATPA is buried in a partially hydrophobic pocket and forces the ligand into the glutamate-like binding mode. The structures provide new insight into the molecular basis of agonist selectivity between AMPA and kainate receptors.

Molecular pharmacology of 4-substituted glutamic acid analogues at ionotropic and metabotropic excitatory amino acid receptors

The pharmacology of (2S,4R)-4-methylglutamic acid, (2S,4S)-4-methylglutamic acid and (S)- and (R)-4-methyleneglutamic acids (obtained in high chemical and enantiomeric purity from racemic 4-methyleneglutamic acid by chiral HPLC using a Crownpak CR(+) column), was examined in binding experiments using rat brain ionotropic glutamate receptors, and in functional assays using cloned metabotropic glutamate (mGlu) receptors. As a notable result of these studies, (2S,4R)-4-methylglutamic acid and (2S,4S)-4-methylglutamic acid were shown to be selective for kainic acid receptors and mGlu receptors (subtypes 1alpha and 2), respectively, whereas (S)-4-methyleneglutamic acid showed high but rather non-selective affinity for the (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA), kainic acid, NMDA and mGlu receptors (subtypes 1alpha and 2). Although none of the compounds were specific for any of the receptor subtypes, the results demonstrate that each of these structurally related compounds has a distinct pharmacological profile.

Chemo-enzymatic synthesis of a series of 2,4-syn-functionalized (S)-glutamate analogues: new insight into the structure-activity relation of ionotropic glutamate receptor subtypes 5, 6, and 7.

( S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system (CNS) activating the plethora of ionotropic Glu receptors (iGluRs) and metabotropic Glu receptors (mGluRs). In this paper, we present a chemo-enzymatic strategy for the enantioselective synthesis of five new Glu analogues 2a- f ( 2d is exempt) holding a functionalized substituent in the 4-position. Nine Glu analogues 2a- j are characterized pharmacologically at native 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA), kainic acid (KA), and N-methyl- d-aspartic acid (NMDA) receptors in rat synaptosomes as well as in binding assays at cloned rat iGluR5-7 subtypes. A detailed in silico study address as to why 2h is a high-affinity ligand at iGluR5-7 ( K i = 3.81, 123, 57.3 nM, respectively), while 2e is only a high affinity ligand at iGluR5 ( K i = 42.8 nM). Furthermore, a small series of commercially available iGluR ligands are characterized in iGluR5-7 binding.