Longitudinal two-photon imaging in somatosensory cortex of behaving mice reveals dendritic spine formation enhancement by subchronic administration of low-dose ketamine.

Ketamine, a well-known anesthetic, has recently attracted renewed attention as a fast-acting antidepressant. A single dose of ketamine induces rapid synaptogenesis, which may underlie its antidepressant effect. To test whether repeated exposure to ketamine triggers sustained synaptogenesis, we administered a sub-anesthetic dose of ketamine (10 mg/kg i.p.) once-daily for 5 days, and repeatedly imaged dendritic spines of the YFP-expressing pyramidal neurons in somatosensory cortex of awake female mice using in vivo two-photon microscopy. We found that the spine formation rate became significantly higher at 72-132 h after the first ketamine injection (but not at 6-24 h), while the rate of elimination of pre-existing spines remained unchanged. In contrast to the net gain of spines observed in ketamine-treated mice, the vehicle-injected control mice exhibited a net loss typical for young-adult animals undergoing synapse pruning. Ketamine-induced spinogenesis was correlated with increased PSD-95 and phosphorylated actin, consistent with formation of new synapses. Moreover, structural synaptic plasticity caused by ketamine was paralleled by a significant improvement in the nest building behavioral assay. Taken together, our data show that subchronic low-dose ketamine induces a sustained shift towards spine formation.

Pharmacological evaluation of a novel phosphodiesterase 10A inhibitor in models of antipsychotic activity and cognition.

In this study, we report the pharmacological effects of a novel PDE10A inhibitor, SEP-39. SEP-39 is a potent (1.0nM) inhibitor of human PDE10A in vitro, with good selectivity (>16000-fold) against other PDEs. In an in vivo occupancy study, the RO50 value was determined to be 0.7mg/kg (p.o.), corresponding to plasma and brain exposures of 28ng/mL and 43ng/g, respectively. Using microdialysis, we show that 3mg/kg (p.o.) SEP-39 significantly increased rat striatal cGMP concentrations. Furthermore, SEP-39 inhibits PCP-induced hyperlocomotion at doses of 1 and 3mg/kg (p.o.) corresponding to 59-86% occupancy. At similar doses in a catalepsy study, the time on the bar was increased but the maximal effect was less than that seen with haloperidol. In an EEG study, 3 and 10mg/kg (p.o.) SEP-39 suppressed REM intensity and increased the latency to REM sleep. We also demonstrate the procognitive effects of SEP-39 in the rat novel object recognition assay. These effects appear to require less PDE10A inhibition than the reversal of PCP-induced hyperlocomotion or EEG effects, as improvements in recognition index were seen at doses of 0.3mg/kg and above. Our data demonstrate that SEP-39 is a potent, orally active PDE10A inhibitor with therapeutic potential in a number of psychiatric indications.

Differential BDNF responses of triple versus dual reuptake inhibition in neuronal and astrocytoma cells as well as in rat hippocampus and prefrontal cortex.

Monoamine reuptake inhibitors increase brain-derived neurotrophic factor (BDNF) activity, and this growth factor is regarded as an interesting target for developing new antidepressant drugs. The aims of this study were to evaluate whether monoaminergic reuptake inhibition increases BDNF in vivo and in vitro as predicted by the neurotrophic hypothesis of depression, and whether triple reuptake inhibition has a superior BDNF response compared to dual reuptake inhibition. Twenty-one days of oral treatment (30 mg/kg) with the dual serotonin/noradrenaline reuptake inhibitor duloxetine or the triple serotonin/noradrenaline/dopamine reuptake inhibitor DOV 216,303 restored BDNF protein levels in the rat hippocampus, which were initially decreased due to injection stress. The prefrontal cortex contained increased BDNF levels only after DOV 216,303 treatment. In vitro, neither duloxetine nor DOV 216,303 altered intracellular BDNF levels in murine HT22 neuronal cells. In contrast, BDNF release was more effectively decreased following treatment with DOV 216,303 in these cells. In rat C62B astrocytomas, both antidepressants increased intracellular BDNF levels at their highest nontoxic concentration. C62B astrocytomas did not release BDNF, even after antidepressant treatment. Increased BDNF levels support the neurotrophic hypothesis of depression, but our findings do not clearly evidence that the BDNF response after triple reuptake inhibitors is more effective than after dual reuptake inhibitors. Moreover, the data suggest that the role of BDNF in neurons and astrocytes is complex and likely depends on factors including specificity of cell types in different brain regions, cell-cell interactions, and different mechanisms of action of antidepressants used.

Synthesis and pharmacological characterization of bicyclic triple reuptake inhibitor 3-aryl octahydrocyclopenta[c]pyrrole analogues.

The present work expands the chemical space known to offer potent inhibition of the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT) and discloses novel bicyclic octahydrocyclopenta[c]pyrrole and octahydro-1H-isoindole scaffolds as potent triple reuptake inhibitors (TRIs) for the potential treatment of depression. Optimized compounds 22a (SERT, NET, DAT, IC(50) = 20, 109, 430 nM), 23a (SERT, NET, DAT, IC(50) = 29, 85, 168 nM), and 26a (SERT, NET, DAT, IC(50) = 53, 150, 140 nM) were highly brain penetrant, active in vivo in the mouse tail suspension test at 10 and 30 mpk PO, and were not generally motor stimulants at doses ranging from 1 to 30 mpk PO. Moderate in vitro cytochrome P450 (CYP) and potassium ion channel Kv11.1 (hERG) inhibition were uncovered as potential liabilities for the chemical series.

Discovery of N-methyl-1-(1-phenylcyclohexyl)methanamine, a novel triple serotonin, norepinephrine, and dopamine reuptake inhibitor.

The current work discloses a novel cyclohexylarylamine chemotype with potent inhibition of the serotonin, norepinephrine, and dopamine transporters and potential for treatment of major depressive disorder. Optimized compounds 1 (SERT, NET, DAT, IC(50)=169, 85, 21 nM) and 42 (SERT, NET, DAT IC(50)=34, 295, 90 nM) were highly brain penetrant, active in vivo in the mouse tail suspension test at 30 mpk po and were not general motor stimulants.

Discovery of N-methyl-1-(1-phenylcyclohexyl)ethanamine, a novel triple serotonin, norepinephrine and dopamine reuptake inhibitor.

Novel chiral cyclohexylaryl amines were developed with potent reuptake inhibition against the serotonin, norepinephrine and dopamine transporters and activity at 10 and 30 mpk PO in the mouse tail suspension test. Prototype compound 31 (SERT, NET, DAT IC(50) ≤ 1, 21, 28 nM) was highly brain penetrant, had minimal CYP and hERG inhibition, and represents a previously undisclosed architecture with potential for treatment of major depressive disorder.

Synthesis and pharmacological evaluation of 4-(3,4-dichlorophenyl)-N-methyl-1,2,3,4-tetrahydronaphthalenyl amines as triple reuptake inhibitors.

The present work describes a series of novel chiral amines that potently inhibit the in vitro reuptake of serotonin, norepinephrine and dopamine (triple reuptake inhibitors) and were active in vivo in a mouse model predictive of antidepressant like activity. The detailed synthesis and in vitro activity and ADME profile of compounds is described, which represent a previously undisclosed triple reuptake inhibitor chemotype.

The anterior cingulate ERK pathway contributes to regulation of behavioral excitement and hedonic activity.

OBJECTIVES: Several intracellular signaling cascades, such as the extracellular signal-regulated kinase (ERK), Wnt-signaling/GSK-3, PLC/PKC, and PI3K pathways, have been shown to be affected directly or indirectly by mood stabilizers. Clinical imaging studies reveal that mood disorders are associated with structural and/or metabolic changes in specific brain regions such as the anterior cingulate cortex (ACC). Here we investigated the extent to which perturbation of one of the affected pathways, the ERK pathway, in the ACC influences affective-related behavior. METHODS: The regional perturbation was induced by two means: local continuous infusion of PD98059, an ERK pathway inhibitor, and microinjection of a lentiviral-mediated gene delivery system encoding functional negative ERK1. The outcomes were monitored with a battery of affective-related tests similar to those used in several previous studies. RESULTS: Compared to their respective controls, rats infused with PD98059 or injected with the lentiviral negative ERK1 construct displayed hyperactivities in multiple tests, exhibited preferentially more open-arm activity in the elevated-plus-maze test, consumed more sweetened liquid in a saccharin preference test, and showed heightened response to amphetamine. CONCLUSIONS: These data support a role for the ACC ERK pathway in the regulation of affective-related behaviors. However, the medial prefrontal cortex (mPFC) comprises at least three other regions that will need to be similarly examined before specific roles of the ACC ERK pathway can be definitively attributed to affective behaviors. Additionally, responses of other signaling pathways to mood stabilizers in these mPFC regions, as well as the limbic regions to which they project, will be important to examine.

Sterically bulky tris(triazolyl)borate ligands as water-soluble analogues of tris(pyrazolyl)borate.

The recently synthesized 3-tert-butyl-5-methyl-1,2,4-triazole reacted with KBH4 to give the new potassium tris(3-tert-butyl-5-methyl-1,2,4-triazolyl)borate K(Ttz(tBu,Me)) ligand. Ttz(tBu,Me) formed a four-coordinate (Ttz(tBu,Me))CoCl complex and five-coordinate (Ttz(tBu,Me))CoNO3 and (Ttz(tBu,Me))ZnOAc complexes. When these complexes were compared to their Tp(tBu,Me) analogues, it was found that Ttz(tBu,Me) resulted in negligible steric differences. K(Ttz(tBu,Me)) is more water-soluble than K(Tp(tBu,Me)), so bulky tris(triazolyl)borate ligands should lead to functional models for enzyme active sites in an aqueous environment and the creation of water-soluble analogues of Tp catalysts.

Satisfaction with end-of-life care for nursing home residents with advanced dementia.

OBJECTIVES: To identify factors associated with satisfaction with care for healthcare proxies (HCPs) of nursing home (NH) residents with advanced dementia. DESIGN: Cross-sectional study. SETTING: Thirteen NHs in Boston. PARTICIPANTS: One hundred forty-eight NH residents aged 65 and older with advanced dementia and their formally designated HCPs. MASUREMENTS: The dependent variable was HCPs' score on the Satisfaction With Care at the End of Life in Dementia (SWC-EOLD) scale (range 10-40; higher scores indicate greater satisfaction). Resident characteristics analyzed as independent variables were demographic information, functional and cognitive status, comfort, tube feeding, and advance care planning. HCP characteristics were demographic information, health status, mood, advance care planning, and communication. Multivariate stepwise linear regression was used to identify factors independently associated with higher SWC-EOLD score. RESULTS: The mean ages+/-standard deviation of the 148 residents and HCPs were 85.0+/-8.1 and 59.1+/-11.7, respectively. The mean SWC-EOLD score was 31.0+/-4.2. After multivariate adjustment, variables independently associated with greater satisfaction were more than 15 minutes discussing advance directives with a care provider at the time of NH admission (parameter estimate=2.39, 95% confidence interval (CI)=1.16-3.61, P<.001), greater resident comfort (parameter estimate=0.10, 95% CI=0.02-0.17, P=.01), care in a specialized dementia unit (parameter estimate=1.48, 95% CI=0.25-2.71, P=.02), and no feeding tube (parameter estimate=2.87, 95% CI=0.46-5.25, P=.02). CONCLUSION: Better communication, greater resident comfort, no tube feeding, and care in a specialized dementia unit are modifiable factors that may improve satisfaction with care in advanced dementia.

Design of a genome-wide siRNA library using an artificial neural network.

The largest gene knock-down experiments performed to date have used multiple short interfering/short hairpin (si/sh)RNAs per gene. To overcome this burden for design of a genome-wide siRNA library, we used the Stuttgart Neural Net Simulator to train algorithms on a data set of 2,182 randomly selected siRNAs targeted to 34 mRNA species, assayed through a high-throughput fluorescent reporter gene system. The algorithm, (BIOPREDsi), reliably predicted activity of 249 siRNAs of an independent test set (Pearson coefficient r = 0.66) and siRNAs targeting endogenous genes at mRNA and protein levels. Neural networks trained on a complementary 21-nucleotide (nt) guide sequence were superior to those trained on a 19-nt sequence. BIOPREDsi was used in the design of a genome-wide siRNA collection with two potent siRNAs per gene. When this collection of 50,000 siRNAs was used to identify genes involved in the cellular response to hypoxia, two of the most potent hits were the key hypoxia transcription factors HIF1A and ARNT.

Unusual alternative splicing within the human kallikrein genes KLK2 and KLK3 gives rise to novel prostate-specific proteins.

Prostate-specific antigen (PSA) and human kallikrein 2 are closely related products of the human kallikrein genes KLK3 and KLK2, respectively. Both PSA and human kallikrein 2 are produced and secreted in the prostate and have important applications in the diagnosis of prostate cancer. We report here the identification of unusual mRNA splice variants of the KLK2 and KLK3 genes that result from inclusion of intronic sequences adjacent to the first exon. The novel proteins encoded by these transcripts, named PSA-linked molecule (PSA-LM) and hK2-linked molecule (K-LM), share only the signal peptide with the original protein product of the respective gene. The mature proteins are entirely different and bear no similarity to the kallikrein family or to other proteins in the databases. As is the case with PSA, PSA-LM is expressed in the secretory epithelial cells of the prostate and is up-regulated in response to androgenic stimulation. A similar pattern of expression is suggested for K-LM.