Transcription and pathway analysis of the superior temporal cortex and anterior prefrontal cortex in schizophrenia.

The molecular basis of schizophrenia is poorly understood; however, different brain regions are believed to play distinct roles in disease symptomology. We have studied gene expression in the superior temporal cortex (Brodmann area 22; BA22), which may play a role in positive pathophysiology, and compared our results with data from the anterior prefrontal cortex (BA10), which shows evidence for a role in negative symptoms. Genome-wide mRNA expression was determined in the BA22 region in 23 schizophrenics and 19 controls and compared with a BA10 data set from the same subjects. After adjustments for confounding sources of variation, we carried out GeneGO pathway enrichment analysis in each region. Significant differences were seen in age-related transcriptional changes between the BA22 and the BA10 regions, 21.8% and 41.4% of disease-associated transcripts showing age association, respectively. After removing age associated changes from our data, we saw the highest enrichment in processes mediating cell adhesion, synaptic contact, cytoskeletal remodelling, and apoptosis in the BA22 region. For the BA10 region, we observed the strongest changes in reproductive signalling, tissue remodelling, and cell differentiation. Further exploratory analysis also identified potentially disease-relevant processes that were undetected in our more stringent primary analysis, including autophagy in the BA22 region and the amyloid process in the BA10 region. Collectively, our analysis suggests disruption of many common pathways and processes underpinning synaptic plasticity in both regions in schizophrenia, whereas individual regions emphasize changes in certain pathways that may help to highlight pathway-specific therapeutic opportunities to treat negative or positive symptoms of the disease.

Orexin receptors in GtoPdb v.2021.3.

Orexin receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Orexin receptors [42]) are activated by the endogenous polypeptides orexin-A and orexin-B (also known as hypocretin-1 and -2; 33 and 28 aa) derived from a common precursor, preproorexin or orexin precursor, by proteolytic cleavage and some typical peptide modifications [109]. Currently the only orexin receptor ligands in clinical use are suvorexant and lemborexant, which are used as hypnotics. Orexin receptor crystal structures have been solved [134, 133, 54, 117, 46].

Behavioural and cognitive abnormalities in an imprinting centre deletion mouse model for Prader-Willi syndrome.

The genes in the imprinted cluster on human chromosome 15q11-q13 are known to contribute to psychiatric conditions such as schizophrenia and autism. Major disruptions of this interval leading to a lack of paternal allele expression give rise to Prader-Willi syndrome (PWS), a neurodevelopmental disorder with core symptoms of a failure to thrive in infancy and, on emergence from infancy, learning disabilities and over-eating. Individuals with PWS also display a number of behavioural problems and an increased incidence of neuropsychiatric abnormalities, which recent work indicates involve aspects of frontal dysfunction. To begin to examine the contribution of genes in this interval to relevant psychological and behavioural phenotypes, we exploited the imprinting centre (IC) deletion mouse model for PWS (PWS-IC(+/-)) and the five-choice serial reaction time task (5-CSRTT), which is primarily an assay of visuospatial attention and response control that is highly sensitive to frontal manipulations. Locomotor activity, open-field behaviour and sensorimotor gating were also assessed. PWS-IC(+/-) mice displayed reduced locomotor activity, increased acoustic startle responses and decreased prepulse inhibition of startle responses. In the 5-CSRTT, the PWS-IC(+/-) mice showed deficits in discriminative response accuracy, increased correct reaction times and increased omissions. Task manipulations confirmed that these differences were likely to be due to impaired attention. Our data recapitulate several aspects of the PWS clinical condition, including findings consistent with frontal abnormalities, and may indicate novel contributions of the imprinted genes found in 15q11-q13 to behavioural and cognitive function generally.

Fluoxetine administration modulates the cytoskeletal microtubular system in the rat hippocampus.

A number of studies suggest that stressful conditions can induce structural alterations in the hippocampus and that antidepressant drugs may prevent such deficits. In particular, the selective serotonin reuptake inhibitor (SSRI) fluoxetine was more effective in modulating different neuronal plasticity phenomena and related molecules in rat hippocampus. Cytoskeletal microtubule dynamics are fundamental to dendrites and axons remodeling, leading to the hypothesis that fluoxetine may affect the microtubular system. However, despite reports of stress-induced alterations in microtubule dynamics by different stressors, only few studies investigated the in vivo effects of antidepressants on microtubules in specific rat brain regions. The present study investigated the dose-related (1, 5, or 10 mg/kg i.p.) effects of acute and chronic (21 days) treatments with fluoxetine on the ratio of hippocampal alpha-tubulin isoforms which is thought to reflect microtubule dynamics. Western Blot analysis was used to quantify alpha-tubulin isoforms, high-performance liquid chromatography and fluorescence detection was used to measure ex vivo monoamine metabolism. The results showed that acute fluoxetine increased the stable forms acetylated and detyrosinated alpha-tubulin. Conversely, chronic fluoxetine decreased acetylated alpha-tubulin, indicative of increased microtubule dynamics. The neuron-specific Delta2-Tubulin was increased by chronic fluoxetine indicating neuronal involvement in the observed cytoskeletal changes. Although acute and chronic fluoxetine similarly altered serotonin metabolism by inhibition of serotonin reuptake, this showed no apparent correlation to the cytoskeletal perturbations. Our findings demonstrate that fluoxetine administration modulates microtubule dynamics in rat hippocampus. The cytoskeletal effect exerted by fluoxetine may eventually culminate in promoting events of structural neuronal remodeling.

The diagnosis of asthma and exercise-induced bronchospasm in division I athletes.

OBJECTIVE: To determine the accuracy of clinically diagnosed exercise-induced bronchospasm (EIB) and asthma among National Collegiate Athletic Association Division I student athletes. DESIGN: Cohort study. SETTING: Division I university athletic department and primary care sports medicine clinic/athletic training room. PATIENTS: All varsity athletes were eligible for the study. Seventy-five participants entered the study; 74 completed all the study protocols. INTERVENTIONS: Study participants underwent measurement of exhaled nitric oxide (eNO), followed by baseline spirometry. Eucapnic voluntary hyperventilation (EVH) was then performed, followed by spirometry every 3 minutes for a total of 21 minutes to measure change in forced expiratory volume in 1 second. MAIN OUTCOME MEASURES: Exhaled nitric oxide levels, baseline spirometry, and response of forced expiratory volume in 1 second to EVH. RESULTS: There were a total of 16 subjects with a positive EVH test. There were 16 (80%) individuals using a bronchodilator who had a negative EVH test versus 4 (20%) who had a positive test. Mean eNO values were different across subject groups defined by treatment status, although not statistically significant. The highest mean eNO value of 24.32 ppb was found in subjects only taking bronchodilators compared with the lowest mean value of 16.75 ppb in athletes who were not taking any medications. CONCLUSIONS: The results from this study provide further evidence to support the need for objective testing to correctly diagnose EIB. These data suggest that measuring eNO may help to distinguish truly isolated EIB from asthma in athletes, but a larger study is needed to confirm these initial observations.

In vitro and in vivo characterization of the non-peptide NK3 receptor antagonist SB-223412 (talnetant): potential therapeutic utility in the treatment of schizophrenia.

Neurokinin-3 (NK3) receptors are concentrated in forebrain and basal ganglia structures within the mammalian CNS. This distribution, together with the modulatory influence of NK3 receptors on monoaminergic neurotransmission, has led to the hypothesis that NK3 receptor antagonists may have therapeutic efficacy in the treatment of psychiatric disorders. Here we describe the in vitro and in vivo characterization of the highly selective NK3 receptor antagonist talnetant (SB-223412). Talnetant has high affinity for recombinant human NK3 receptors (pKi 8.7) and demonstrates selectivity over other neurokinin receptors (pKi NK2 = 6.6 and NK1<4). In native tissue-binding studies, talnetant displayed high affinity for the guinea pig NK3 receptor (pKi 8.5). Functionally, talnetant competitively antagonized neurokinin B (NKB)-induced responses at the human recombinant receptor in both calcium and phosphoinositol second messenger assay systems (pA2 of 8.1 and 7.7, respectively). In guinea pig brain slices, talnetant antagonized NKB-induced increases in neuronal firing in the medial habenula (pKB = 7.9) and senktide-induced increases in neuronal firing in the substantia nigra pars compacta (pKB = 7.7) with no diminution of maximal agonist efficacy, suggesting competitive antagonism at native NK3 receptors. Talnetant (3-30 mg/kg i.p.) significantly attenuated senktide-induced 'wet dog shake' behaviors in the guinea pig in a dose-dependent manner. Microdialysis studies demonstrated that acute administration of talnetant (30 mg/kg i.p.) produced significant increases in extracellular dopamine and norepinephrine in the medial prefrontal cortex and attenuated haloperidol-induced increases in nucleus accumbens dopamine levels in the freely moving guinea pigs. Taken together, these data demonstrate that talnetant is a selective, competitive, brain-penetrant NK3 receptor antagonist with the ability to modulate mesolimbic and mesocortical dopaminergic neurotransmission and hence support its potential therapeutic utility in the treatment of schizophrenia.

Pharmacological assessment of m1 muscarinic acetylcholine receptor-gq/11 protein coupling in membranes prepared from postmortem human brain tissue.

Using a selective Galpha(q/11) protein antibody capture guanosine 5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) binding approach, it has been possible to perform a quantitative pharmacological examination of the functional activity of the M(1) muscarinic acetylcholine receptor (mAChR) in membranes prepared from human postmortem cerebral cortex. Oxotremorine-M caused a > or = 2-fold increase in [35S]GTPgammaS-Galpha(q/11) binding with a pEC(50) of 6.06 +/- 0.16 in Brodmann's areas 23 and 25 that was almost completely inhibited by preincubation of membranes with the M(1) mAChR subtype-selective antagonist muscarinic toxin-7. In addition, the orthosteric and allosteric agonists, xanomeline [3(3-hexyloxy-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine] and AC-42 (4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl]-piperidine hydrogen chloride), increased [35S]-GTPgammaS-Galpha(q/11) binding, but with reduced intrinsic activities, inducing maximal responses that were 42 +/- 1 and 44 +/- 2% of the oxotremorine-M-induced response, respectively. These data indicate that the M(1) receptor is the predominant mAChR subtype coupling to the Galpha(q/11) G protein in these brain regions and that it is possible to quantify the potency and intrinsic activity of full and partial M(1) mAChR receptor agonists in postmortem human brain using a selective Galpha(q/11) protein antibody capture [35S]GTPgammaS binding assay.

The selective 5-HT6 receptor antagonists SB-271046 and SB-399885 potentiate NCAM PSA immunolabeling of dentate granule cells, but not neurogenesis, in the hippocampal formation of mature Wistar rats.

While there is now substantial evidence that 5-HT(6) antagonism leads to significantly improved cognitive ability, the mechanism(s) and/or pathway(s) involved are poorly understood. We have evaluated the consequence of chronic administration of the 5-HT(6) receptor antagonists SB-271046 and SB-399885 on neural cell adhesion molecule polysialylation state (NCAM PSA), a neuroplastic mechanism necessary for memory consolidation. Quantitative analysis of NCAM PSA immunopositive neurons in the dentate gyrus of drug-treated animals revealed a dose-dependent increase in polysialylated cell frequency following treatment with both SB-271046 and SB-399885. These effects could not be attributed to increased neurogenesis, as no difference in the rate of bromodeoxyuridine incorporation was apparent between the control and drug-treated groups. A substantial increase in the frequency of polysialylated cells in layer II of the entorhinal and perirhinal cortices was also observed, brain regions not previously associated with neurogenesis. Chronic treatment with SB-271046 or SB-399885 also significantly increased the activation of dentate polysialylation that is specific to learning. This effect does not occur with other cognition-enhancing drugs, such as tacrine, and this action potentially differentiates 5-HT(6) receptor antagonism as an unique neuroplastic mechanism for cognitive processes which may slow or reverse age/neurodegenerative related memory deficits.

SB-649915-B, a novel 5-HT1A/B autoreceptor antagonist and serotonin reuptake inhibitor, is anxiolytic and displays fast onset activity in the rat high light social interaction test.

Preclinically, the combination of an SSRI and 5-HT autoreceptor antagonist has been shown to reduce the time to onset of anxiolytic activity compared to an SSRI alone. In accordance with this, clinical data suggest the coadministration of an SSRI and (+/-) pindolol can decrease the time to onset of anxiolytic/antidepressant activity. Thus, the dual-acting novel SSRI and 5-HT(1A/B) receptor antagonist, SB-649915-B, has been assessed in acute and chronic preclinical models of anxiolysis. SB-649915-B (0.1-1.0 mg/kg, i.p.) significantly reduced ultrasonic vocalization in male rat pups separated from their mothers (ED(50) of 0.17 mg/kg). In the marmoset human threat test SB-649915-B (3.0 and 10 mg/kg, s.c.) significantly reduced the number of postures with no effect on locomotion. In the rat high light social interaction (SI), SB-649915-B (1.0-7.5 mg/kg, t.i.d.) and paroxetine (3.0 mg/kg, once daily) were orally administered for 4, 7, and 21 days. Ex vivo inhibition of [(3)H]5-HT uptake was also measured following SI. SB-649915-B and paroxetine had no effect on SI after 4 days. In contrast to paroxetine, SB-649915-B (1.0 and 3.0 mg/kg, p.o., t.i.d.) significantly (p<0.05) increased SI time with no effect on locomotion, indicative of an anxiolytic-like profile on day 7. Anxiolysis was maintained after chronic (21 days) administration by which time paroxetine also increased SI significantly. 5-HT uptake was inhibited by SB-649915-B at all time points to a similar magnitude as that seen with paroxetine. In conclusion, SB-649915-B is acutely anxiolytic and reduces the latency to onset of anxiolytic behavior compared to paroxetine in the SI model.

1,2,4-triazol-3-yl-thiopropyl-tetrahydrobenzazepines: a series of potent and selective dopamine D(3) receptor antagonists.

The discovery of new highly potent and selective dopamine D3 receptor antagonists has recently permitted characterization of the role of the dopamine D3 receptor in a wide range of preclinical animal models. A novel series of 1,2,4-triazol-3-yl-thiopropyl-tetrahydrobenzazepines demonstrating a high level of D3 affinity and selectivity with an excellent pharmacokinetic profile is reported here. In particular, the pyrazolyl derivative 35 showed good oral bioavailability and brain penetration associated with high potency and selectivity in vitro. In vivo characterization of 35 confirmed that this compound blocks the expression of nicotine- and cocaine-conditioned place preference in the rat, prevents nicotine-triggered reinstatement of nicotine-seeking behavior in the rat, reduces oral operant alcohol self-administration in the mouse, increases extracellular levels of acetylcholine in the rat medial prefrontal cortex, and potentiates the amplitude of the relative cerebral blood volume response to d-amphetamine in a regionally specific manner in the rat brain.

Simultaneous blockade of 5-HT1A/B receptors and 5-HT transporters results in acute increases in extracellular 5-HT in both rats and guinea pigs: in vivo characterization of the novel 5-HT1A/B receptor antagonist/5-HT transport inhibitor SB-649915-B.

RATIONALE: The delay in onset and treatment resistance of subpopulations of depressed patients to conventional serotonin reuptake inhibitors has lead to new drug development strategies to produce agents with improved antidepressant efficacy. OBJECTIVES: We report the in vivo characterization of the novel 5-HT(1A/1B) autoreceptor antagonist/5-HT transporter inhibitor (6-[(1-{2-[(2-methyl-5-quinolinyl)oxy]ethyl}-4-piperidinyl)methyl]-2H-1,4-benzoxazin-3(4H)-one), SB-649915-B. MATERIALS AND METHODS: Ex vivo binding was used to ascertain 5-HT(1A) receptor and serotonin transporter occupancy. 8-OH-DPAT-induced hyperlocomotion and SKF-99101-induced elevation of seizure threshold were used as markers of central blockade of 5-HT(1A) and 5-HT(1B) receptors, respectively. In vivo electrophysiology in the rat dorsal raphe and microdialysis in freely moving guinea pigs and rats were used to evaluate the functional outcome of SB-649915-B. RESULTS: SB-649915-B (1-10 mg/kg p.o.) produced a dose-related inhibition of 5-HT(1A) receptor radioligand binding and inhibited ex vivo [(3)H]5-HT uptake in both guinea pig and rat cortex. SB-649915-B (0.1-10 mg/kg p.o.) reversed both 8-OH-DPAT-induced hyperlocomotor activity and SKF-99101-induced elevation of seizure threshold in the rat, demonstrating in vivo blockade of both 5-HT(1A) and 5-HT(1B) receptors, respectively. SB-649915-B (0.1-3 mg/kg i.v.) produced no change in raphe 5-HT neuronal cell firing per se but attenuated the inhibitory effect of 8-OH-DPAT. Acute administration of SB-649915-B resulted in increases (approximately two- to threefold) in extracellular 5-HT in the cortex of rats and the dentate gyrus and cortex of guinea pigs. CONCLUSIONS: Based on these data, one may speculate that the 5-HT autoreceptor antagonist/5-HT transport inhibitor SB-649915-B will have therapeutic efficacy in the treatment of affective disorders with the potential for a faster onset of action compared to current selective serotonin reuptake inhibitors.

SB-699551-A (3-cyclopentyl-N-[2-(dimethylamino)ethyl]-N-[(4'-{[(2-phenylethyl)amino]methyl}-4-biphenylyl)methyl]propanamide dihydrochloride), a novel 5-ht5A receptor-selective antagonist, enhances 5-HT neuronal function: Evidence for an autoreceptor role for the 5-ht5A receptor in guinea pig brain.

This study utilised the selective 5-ht(5A) receptor antagonist, SB-699551-A (3-cyclopentyl-N-[2-(dimethylamino)ethyl]-N-[(4'-{[(2-phenylethyl)amino]methyl}-4-biphenylyl)methyl]propanamide dihydrochloride), to investigate 5-ht5A receptor function in guinea pig brain. SB-699551-A competitively antagonised 5-HT-stimulated [35S]GTPgammaS binding to membranes from human embryonic kidney (HEK293) cells transiently expressing the guinea pig 5-ht5A receptor (pA2 8.1+/-0.1) and displayed 100-fold selectivity versus the serotonin transporter and those 5-HT receptor subtypes (5-HT(1A/B/D), 5-HT2A/C and 5-HT7) reported to modulate central 5-HT neurotransmission in the guinea pig. In guinea pig dorsal raphe slices, SB-699551-A (1 microM) did not alter neuronal firing per se but attenuated the 5-CT-induced depression in serotonergic neuronal firing in a subpopulation of cells insensitive to the 5-HT1A receptor-selective antagonist WAY-100635 (100 nM). In contrast, SB-699551-A (100 or 300 nM) failed to affect both electrically-evoked 5-HT release and 5-CT-induced inhibition of evoked release measured using fast cyclic voltammetry in vitro. SB-699551-A (0.3, 1 and 3 mg/kg s.c.) did not modulate extracellular levels of 5-HT in the guinea pig frontal cortex in vivo. However, when administered in combination with WAY-100635 (0.3 mg/kg s.c.), SB-699551-A (0.3, 1 or 3 mg/kg s.c.) produced a significant increase in extracellular 5-HT levels. These studies provide evidence for an autoreceptor role for the 5-ht5A receptor in guinea pig brain.

Long-lasting changes in behavioural and neuroendocrine indices in the rat following neonatal maternal separation: gender-dependent effects.

Neonatal maternal separation (MS) has been used to model long-term changes in neurochemistry and behaviour associated with exposure to early-life stress. This study characterises changes in behavioural and neuroendocrine parameters following MS. On postnatal days (PND) 3-15, male and female Long-Evans rats underwent 3 h daily MS. Non-handled (NH) control offspring remained with the dams. Starting at PND 90, behaviour was assessed at weekly intervals in the elevated plus-maze, elevated T-maze, and locomotor activity boxes, and body weight monitored throughout. At the end of the study, adrenals were weighed and blood collected for analysis of plasma corticosterone and adrenocorticotropic hormone (ACTH) under basal conditions and following restraint stress. As adults, MS weighed more than NH animals. Activity on the open arms of the plus-maze was similar between MS and NH animals. In the T-maze, MS males had shorter emergence latencies than their NH counterparts. Spontaneous ambulation in a novel environment was significantly higher in MS than in NH animals, and males exhibited overall lower activity than females. Basal plasma corticosterone was lower in MS than in NH females, but no rearing condition difference was observed following restraint stress. Females had higher corticosterone and ACTH levels than males, whereas adrenal glands of MS animals weighed less than those of NH controls. The MS paradigm caused long-term gender dependent effects on behaviour and HPA axis status. The consistent gender differences confirm and expand existing results showing altered anxiety and stress reactivity in male and female rats.

Novel pharmacotherapeutic approaches for the treatment of drug addiction and craving.

Pharmacological agents have shown limited efficacy and consistency in the treatment of drug addiction. Hence, the development of new medications with improved long-term efficacy and reduced side effects should be given a high priority given the costs to society associated with drug abuse and drug-related pathologies. Neurochemical systems can be significantly altered by repeated exposure to drugs of abuse. These long-term molecular and neurochemical changes might, in turn, explain the core features of addiction--the compulsive seeking and taking of the drug--as well as the risk of relapse.

Dopamine D3 receptor antagonism inhibits cocaine-seeking and cocaine-enhanced brain reward in rats.

dopamine D3 receptor is preferentially localized to the mesocorticolimbic dopaminergic system and has been hypothesized to play a role in cocaine addiction. To study the involvement of the D3 receptor in brain mechanisms and behaviors commonly assumed to be involved in the addicting properties of cocaine, the potent and selective D3 receptor antagonist trans-N-[4-[2-(6-cyano-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl] cyclohexyl]-4-quinolininecarboxamide (SB-277011-A) was administered to laboratory rats, and the following measures were assessed: (1) cocaine-enhanced electrical brain-stimulation reward, (2) cocaine-induced conditioned place preference, and (3) cocaine-triggered reinstatement of cocaine seeking behavior. Systemic injections of SB-277011-A were found to (1) block enhancement of electrical brain stimulation reward by cocaine, (2) dose-dependently attenuate cocaine-induced conditioned place preference, and (3) dose-dependently attenuate cocaine-triggered reinstatement of cocaine seeking behavior. Thus, D3 receptor blockade attenuates both the rewarding effects of cocaine and cocaine-induced drug-seeking behavior. These data suggest an important role for D3 receptors in mediating the addictive properties of cocaine and suggest that blockade of dopamine D3 receptors may constitute a new and useful target for prospective pharmacotherapies for cocaine addiction.

5-HT6 receptor antagonists improve performance in an attentional set shifting task in rats.

RATIONALE AND OBJECTIVE: Performance on the Wisconsin Card Sorting Test (WCST), which requires patients to 'shift attention' between stimulus dimensions (sorting categories), is impaired in diseases such as schizophrenia. The rat attentional set shifting task is an analogue of the WCST. Given that 5-HT(6) receptor antagonists improve cognitive performance and influence cortical neurochemistry in rats, the present study investigated the effects of 5-HT(6) receptor antagonists upon attentional set shifting in rats. METHODS: Rats were tested in this paradigm following sub-chronic SB-399885-T or SB-271046-A (both 10 mg kg(-1) bid, p.o. for 8 days prior to testing and either 4 or 2 h prior to testing on day 9, respectively). Rats were trained to dig in baited bowls for a food reward and to discriminate based on odour or digging media (Habituation, day 8). In a single session (day 9), rats performed a series of discriminations, including reversals (REV), intra-dimensional (ID) and extra-dimensional (ED) shifts. RESULTS: Neither compound altered performance during Habituation. On the test day, both SB-399885-T and SB-271046-A reduced the total trials to reach criterion and the total errors made when data were collapsed across all discriminations (P<0.05-0.01). Further, both compounds significantly reduced the trials to criterion for REV-1 (P<0.05-0.01) and abolished the ID/ED shift. SB-399885-T, but not SB-271046-A, reduced trials required to complete the ED shift (P<0.05) and the number of errors made during completion of the ID (P<0.05) and ED shifts (P<0.01). CONCLUSION: 5-HT(6) receptor antagonists improved performance in the attentional set shifting task and may have therapeutic potential in the treatment of disorders where cognitive deficits are a feature, including schizophrenia.

Effect of vilazodone on 5-HT efflux and re-uptake in the guinea-pig dorsal raphe nucleus.

The effect of vilazodone, a putative selective serotonin re-uptake inhibitor (SSRI) with 5-HT (5-hydroxytryptamine)(1A) receptor partial agonist activity, was investigated on 5-HT efflux and 5-HT re-uptake half life in the guinea-pig dorsal raphe nucleus, using in vitro fast cyclic voltammetry. The SSRI, fluoxetine, significantly increased 5-HT efflux. In contrast, vilazodone had no effect on 5-HT efflux at 100 nM but significantly decreased 5-HT efflux at 1 microM. Co-perfusion of 8-OH-DPAT (+/-8-hydroxy-2-(di-n-propylamino)tetralin) with fluoxetine significantly attenuated the fluoxetine-induced increase in 5-HT efflux. Co-perfusion of WAY 100635 with vilazodone did not attenuate the effect of vilazodone alone. In addition, the re-uptake half life for 5-HT was significantly increased by both fluoxetine and vilazodone. In conclusion, we have demonstrated that vilazodone (100 nM, 1 microM), in the guinea-pig dorsal raphe nucleus, blocks the serotonin transporter but does not display 5-HT(1A) receptor agonism.

Predicting drug efficacy for cognitive deficits in schizophrenia.

The purpose of this article is to discuss the prediction of cognitive enhancement in schizophrenia from preclinical data. Despite increasing focus on the significance of cognitive impairment in schizophrenia, the progress of novel treatments has been slow. Hyman and Fenton's identification of a "translational gap" between preclinical and clinical science underscores the need to revise preclinical, clinical, and regulatory practice. A review of the clinical literature identifies evidence for some cognitive benefits with current antipsychotics. The magnitude of these effects may, in some cases, be too small to be functionally relevant, and many studies are methodologically flawed, but the data might nevertheless allow translational links to be identified between clinical and preclinical studies. The literature is reviewed to determine if the cognitive signal reported in clinical studies is detectable in preclinical studies. The effects of antipsychotics on prepulse-inhibition deficits in animals is robust and demonstrates a reversal of drug-induced and developmentally induced deficits, although predictive links to the clinic are not well established. The preclinical literature on antipsychotic effects on attention, learning and memory, and recognition and executive function shows, with rare exceptions, impaired learning or task performance, rather than improvement. In general, therefore, preclinical studies have not detected the small pro-cognitive signal evident in the clinical literature. A number of factors may account for this. Effective closure of the translation gap for cognitive deficits in schizophrenia will require the design of a coherent preclinical strategy, and some of the potential elements of such a strategy are outlined and discussed.

5-HT7 receptors.

Following the cloning of the 5-HT(7) receptor in 1993, studies to investigate 5-HT(7) receptor function in native tissues focused on identifying functional correlates that matched the pharmacological profile determined for the cloned receptor. Studies in peripheral tissues established that the 5-HT(7) receptor mediates the relaxation of smooth muscle, including the gastrointestinal tract and cardiovascular systems. Although a number of studies provided preliminary evidence for a role for the 5-HT(7) receptor in the circadian pacemaker function of the suprachiasmatic nucleus (SCN), additional studies to investigate 5-HT(7) receptor function in other brain regions have, until recently, been hindered by the absence of 5-HT(7) receptor-selective ligands. More recently, a number of 5-HT(7) receptor-selective antagonists including, SB-269970-A and SB-656104-A have been developed. Studies utilising these compounds suggest that the 5-HT(7) receptor modulates neuronal function in a number of brain areas including the hippocampus and thalamus. In turn, these findings suggest that 5-HT(7) receptor-selective ligands might prove therapeutically useful for the treatment of psychiatric disorders. In this respect there is increasing evidence to suggest that the 5-HT(7) receptor plays a role in the control of both circadian rhythms and sleep and might therefore represent a therapeutic target for the treatment of those disorders in which disturbances in circadian rhythms and sleep architecture are thought to be contributory factors. Furthermore, there is evidence to suggest that the receptor may play a role in other CNS disorders including, anxiety, cognitive disturbances and also migraine probably via both peripheral and central mechanisms. Although further studies are required to confirm the potential role of the receptor in such disorders, findings to date suggest there are exciting opportunities for the development of novel therapeutic agents acting either selectively at the 5-HT(7) receptor or whose profile of action includes an interaction with this receptor.

Selective antagonism at dopamine D3 receptors enhances monoaminergic and cholinergic neurotransmission in the rat anterior cingulate cortex.

Recent neuroanatomical and functional investigations focusing on dopamine (DA) D(3) receptors have suggested a potential role of this receptor in psychiatric diseases such as schizophrenia and drug dependence. In line with the key role of the prefrontal cortex in psychiatric disorders, the present study aimed at assessing the effects of the acute systemic administration of the selective DA D(3) receptor antagonist SB-277011-A on the in vivo extracellular levels of monoamines (DA, norepinephrine (NE), and serotonin (5-HT)) and acetylcholine (ACh) in the anterior cingulate subregion of the medial prefrontal cortex. The in vivo neurochemical profile of SB-277011-A (10 mg/kg, i.p.) in the anterior cingulate cortex was compared with both typical and atypical antipsychotics including clozapine (10 mg/kg, s.c.), olanzapine (10 mg/kg, s.c.), sulpiride (10 mg/kg, s.c.), and haloperidol (0.5 mg/kg, s.c.). The acute administration of SB-277011-A, clozapine, and olanzapine produced a significant increase in extracellular levels of DA, NE, and ACh without affecting levels of 5-HT. Sulpiride also significantly increased extracellular DA, but with a delayed onset over SB-277011-A, clozapine, and olanzapine. In contrast, haloperidol failed to alter any of the three monoamines and ACh in the anterior cingulate cortex. These findings add to a growing body of evidence suggesting a differentiation between typical and atypical antipsychotic drugs (APDs) in the anterior cingulate cortex and a role of DA D(3) receptors in desired antipsychotic drug profile. Similar to their effects on DA and NE, SB-277011-A, clozapine, and olanzapine increased extracellular levels of ACh, whereas haloperidol and sulpiride did not alter ACh. The results obtained in the present study provide evidence of the important role of DA D(3) receptors in the effect of pharmacotherapeutic agents that are used for the treatment of psychiatric disorders such as schizophrenia and drug dependence.