Selective up-regulation of cannabinoid CB1 receptor coupling to Go-proteins in suicide victims with mood disorders.

Brain endocannabinoid system is proposed to play a role in the pathogenesis of affective disorders. In the present study, we analyzed the functionality of the cannabinoid receptor type 1 (CB1 receptor) at different transduction levels in prefrontal cortex (PFC) of depressed suicide victims. We examined stimulation of [35S]GTPγS binding, activation of Gα protein subunits and inhibition of adenylyl cyclase by the cannabinoid agonist WIN55,212-2, as well as [3H]CP55,940 binding, in PFC homogenates from suicide victims with major depression (MD) and matched control subjects. CB1 receptor-stimulated [35S]GTPγS binding was significantly greater in the PFC of MD compared with matched controls (23%, p < 0.05). This increase was most evident in the PFC from MD subgroup with negative blood test for antidepressants (AD) at the time of death (AD-free) (38%, p < 0.05), being absent when comparing the AD-treated MD cases with their controls. The density of CB1 receptors and their coupling to adenylyl cyclase were similar between MD and control cases, regardless of the existence of AD intake. Analysis of [35S]GTPγS-labelled Gα subunits allowed for the detection of upregulated CB1 receptor coupling to Gαo, but not to Gαi1, Gαi2, Gαi3, Gαz subunits, in the PFC from AD-free MD suicides. These results suggest that increased CB1 receptor functionality at the Gαi/o protein level in the PFC of MD subjects is due to enhanced coupling to Gαo proteins and might be modulated by AD intake. These data provide new insights into the role of endocannabinoid neurotransmission in the pathobiology of MD and suggest its regulation by ADs.

Effects of aripiprazole, quetiapine and ziprasidone on plasma prolactin levels in individuals with first episode nonaffective psychosis: Analysis of a randomized open-label 1year study.

RATIONALE: Hyperprolactinemia is considered a troubling adverse effect of antipsychotics. Direct comparisons among second generation antipsychotics are scant in clinical practice. We hypothesize prolactin-sparing second-generation antipsychotics may have differential effects on prolactin levels and that they may be influenced by sex. OBJECTIVES: To explore the differential effect of three widely used prolactin-sparing antipsychotics, aripiprazole, quetiapine and ziprasidone, on prolactin plasma levels in first episode non-affective psychosis during a 1year of treatment. METHOD: From October 2005 to January 2011 a prospective, randomized, open-label study was undertaken. 141 patients who were randomly allocated to aripiprazole (N=56), quetiapine (N=36) or ziprasidone (N=49) were analyzed. The main outcome was differences in prolactin plasma levels over 1year follow-up among the three antipsychotics. Prolactin levels had a skewed distribution and therefore they were log-transformed before statistical analyses. RESULTS: Male patients on aripiprazole had a lower risk of suffering an increase on prolactin plasma levels (N=71; F=12.645; p<0.001). There was a gender effect with smaller changes in mean prolactin values only in males. Aripiprazole had a reduced risk of hyperprolactinemia (aripiprazole 19.6%) compared to quetiapine (44.4%) and ziprasidone (32.7%) (p=0.038); and quite similar findings were found when investigating males (p=0.040). No significant differences were found in females. The percentages of mild prolactin excess were: 14.3% on aripiprazole, 36.1% on quetiapine and 18.4% on ziprasidone (χ2=6.611 p=0.037). CONCLUSIONS: Our findings provide additional evidence of differential effects of three sparing-prolactin antipsychotics on prolactin release and may help clinicians to decide among therapeutic options.

Behavioral, neurochemical and molecular changes after acute deep brain stimulation of the infralimbic prefrontal cortex.

Deep brain stimulation (DBS) is a treatment that has shown some efficacy in treatment-resistant depression. In particular, DBS of the subcallosal cingulate gyrus (Brodmann's area 25, Cg25) has been successfully applied to treat refractory depression. In the rat, we have demonstrated that DBS applied to infralimbic (IL) cortex elevates the levels of glutamate and monoamines in the prefrontal cortex, and requires the stimulation of cortical α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors for its antidepressant-like effects. However, the molecular targets of IL DBS are not fully known. To gain insight into these pathways, we have investigated whether IL DBS is able to reverse the behavioral, biochemical and molecular changes exhibited by the olfactory bulbectomized (OBX) rat. Our results revealed that 1 h IL DBS diminished hyperlocomotion, hyperemotionality and anhedonia, and increased social interaction shown by the OBX rats. Further, IL DBS increased prefrontal efflux of glutamate and serotonin in both sham-operated and OBX rats. With regard to molecular targets, IL DBS increases the synthesis of brain-derived neurotrophic factor (BDNF) and the GluA1 AMPA receptor subunit, and stimulates the Akt/mammalian target of rapamycin (mTOR) as well as the AMPA receptor/c-AMP response element binding (CREB) pathways. Temsirolimus, a known in vivo mTOR blocker, suppressed the antidepressant-like effect of IL DBS in naïve rats in the forced swim test, thus demonstrating for the first time that mTOR signaling is required for the antidepressant-like effects of IL DBS, which is in line with the antidepressant response of other rapid-acting antidepressant drugs.

Clinical outcome after antipsychotic treatment discontinuation in functionally recovered first-episode nonaffective psychosis individuals: a 3-year naturalistic follow-up study.

OBJECTIVE: The timing of antipsychotic discontinuation in patients who have fully recovered from their initial episode of psychosis is still open to discussion. We aimed to evaluate the risk of symptom recurrence during the 3 years after antipsychotic discontinuation in a sample of functionally recovered first-episode nonaffective psychosis (FEP) patients (DSM-IV criteria) with schizophrenia spectrum disorder. METHOD: Participants in this open-label, nonrandomized, prospective study were drawn from an ongoing longitudinal intervention program of FEP from a university hospital setting in Spain. From July 2004 to February 2011, functionally recovered FEP individuals were eligible if they met the inclusion criteria of (1) a minimum of 18 months on antipsychotic treatment, (2) clinical remission for at least 12 months, (3) functional recovery for at least 6 months, and (4) stabilization at the lowest effective doses for at least 3 months. Forty-six individuals who were willing to discontinue medication were included in the discontinuation group (target group). Twenty-two individuals opted to stay on the prescribed antipsychotic medication and therefore were included in the maintenance group (control group). Primary outcome measures were relapse rate at 18 and 36 months and time to relapse. RESULTS: The rates of relapse over the 3-year period were 67.4% (31 of 46) in the discontinuation group and 31.8% (7 of 22) in the maintenance group. The mean time to relapse was 209 (median = 122) days and 608 (median = 607) days, respectively (log rank = 10.106, P = .001). The resumption of antipsychotic medication after the relapse occurred was associated with clinical stability and lack of further relapses. When the overall group of relapsed individuals from the 2 conditions (N = 38) was compared to those who remained asymptomatic after 3 years (N = 30), there were significant differences (P < .05) in total scores on the Scale for the Assessment of Negative Symptoms, the Clinical Global Impressions scale, and the Disability Assessment Schedule. CONCLUSIONS: Antipsychotic treatment discontinuation in individuals who had accomplished a functional recovery after a single psychotic episode was associated with a high risk of symptom recurrence. Relapsed individuals had a greater severity of symptoms and lower functional status after 3 years. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02220504.

Small Molecule Inhibition of ERK Dimerization Prevents Tumorigenesis by RAS-ERK Pathway Oncogenes.

Nearly 50% of human malignancies exhibit unregulated RAS-ERK signaling; inhibiting it is a valid strategy for antineoplastic intervention. Upon activation, ERK dimerize, which is essential for ERK extranuclear, but not for nuclear, signaling. Here, we describe a small molecule inhibitor for ERK dimerization that, without affecting ERK phosphorylation, forestalls tumorigenesis driven by RAS-ERK pathway oncogenes. This compound is unaffected by resistance mechanisms that hamper classical RAS-ERK pathway inhibitors. Thus, ERK dimerization inhibitors provide the proof of principle for two understudied concepts in cancer therapy: (1) the blockade of sub-localization-specific sub-signals, rather than total signals, as a means of impeding oncogenic RAS-ERK signaling and (2) targeting regulatory protein-protein interactions, rather than catalytic activities, as an approach for producing effective antitumor agents.

Building up careers in translational neuroscience and mental health research: Education and training in the Centre for Biomedical Research in Mental Health.

The number of large collaborative research networks in mental health is increasing. Training programs are an essential part of them. We critically review the specific implementation of a research training program in a translational Centre for Biomedical Research in Mental Health in order to inform the strategic integration of basic research into clinical practice to have a positive impact in the mental health system and society. Description of training activities, specific educational programs developed by the research network, and challenges on its implementation are examined. The Centre for Biomedical Research in Mental Health has focused on training through different activities which have led to the development of an interuniversity master's degree postgraduate program in mental health research, certified by the National Spanish Agency for Quality Evaluation and Accreditation. Consolidation of training programs within the Centre for Biomedical Research in Mental Health has considerably advanced the training of researchers to meet competency standards on research. The master's degree constitutes a unique opportunity to accomplish neuroscience and mental health research career-building within the official framework of university programs in Spain.

The endocannabinoid system is altered in the post-mortem prefrontal cortex of alcoholic subjects.

There is strong biochemical, pharmacological and genetic evidence for the involvement of the endocannabinoid system (ECS) in alcohol dependence. However, the majority of studies have been performed in animal models. The aim of the present study was to assess the state of the CB1 receptor, the enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), and the extracellular signal-regulated kinase (ERK) and cyclic-AMP response element-binding protein (CREB) in the post-mortem prefrontal cortex of alcoholic subjects. Experiments were performed in samples from 44 subjects classified in four experimental groups: (1) non-suicidal alcoholic subjects (n = 11); (2) suicidal alcoholic subjects (n = 11); (3) non-alcoholic suicide victims (n = 11); and (4) control subjects (n = 11). We did not observe statistically significant differences in CB1 mRNA relative expression among the four experimental groups. Conversely, our results showed an increase in CB1 receptor protein expression in the prefrontal cortex of the suicidal alcoholic group (127.2 ± 7.3%), with no changes in functionality with regard to either G protein activation or the inhibition of adenylyl cyclase. In parallel, alcoholic subjects presented lower levels of MAGL activity, regardless of the cause of death. A significant decrease in the active form of ERK and CREB levels was also observed in both alcoholic groups. Taken together, our data are consistent with a role for the ECS in the neurobiological mechanisms underlying alcoholism. Moreover, the alterations reported here should be of great interest for the therapeutic treatment of this chronic psychiatric disease.

Increased SP4 and SP1 transcription factor expression in the postmortem hippocampus of chronic schizophrenia.

Altered levels of transcription factor specificity protein 4 (SP4) and 1 (SP1) in the cerebellum, prefrontal cortex and/or lymphocytes have been reported in severe psychiatric disorders, including early psychosis, bipolar disorder, and chronic schizophrenia subjects who have undergone long-term antipsychotic treatments. SP4 transgenic mice show altered hippocampal-dependent psychotic-like behaviours and altered development of hippocampal dentate gyrus. Moreover, NMDAR activity regulates SP4 function. The aim of this study was to investigate SP4 and SP1 expression levels in the hippocampus in schizophrenia, and the possible effect of antipsychotics and NMDAR blockade on SP protein levels in rodent hippocampus. We analysed SP4 and SP1 expression levels in the postmortem hippocampus of chronic schizophrenia (n = 14) and control (n = 11) subjects by immunoblot and quantitative RT-PCR. We tested the effect of NMDAR blockade on SP factors in the hippocampus of mouse treated with an acute dose of MK801. We also investigated the effect of subacute treatments with haloperidol and clozapine on SP protein levels in the rat hippocampus. We report that SP4 protein and both SP4 and SP1 mRNA expression levels are significantly increased in the hippocampus in chronic schizophrenia. Likewise, acute treatment with MK801 increased both SP4 and SP1 protein levels in mouse hippocampus. In contrast, subacute treatment with haloperidol and clozapine did not significantly alter SP protein levels in rat hippocampus. These results suggest that SP4 and SP1 upregulation may be part of the mechanisms deregulated downstream of glutamate signalling pathways in schizophrenia and might be contributing to the hippocampal-dependent cognitive deficits of the disorder.

Signaling pathways involved in antidepressant-induced cell proliferation and synaptic plasticity.

In the last years it has been proposed that the antidepressant action is mediated not only by changes in monoamine levels but also in association with modifications involving cell proliferation and plasticity in some brain limbic areas as hippocampus, and also frontal cortex and amygdala. This leads to the merging of the classic "monoaminergic hypothesis of depression", with the newer "neurotrophic hypothesis of depression". Here we review two important signaling pathways: the Wnt/ß-catenin pathway -implicated in cellular proliferation and synaptic plasticity- that is downregulated in major depression and upregulated after antidepressant treatment; and the mTOR pathway -controling synaptic plasticity- recently related to present disrupted functioning in major depression, and as the target of some drugs with fast-acting potential antidepressant action. These pieces of evidences are confirmed in a variety of animal models of depression and are predictive of antidepressant actions. We also review the role of another two important neurotrophic factors: brain derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) that mediate the antidepressant effects. All of the above intracellular pathways interact by a crosstalk mediated by Akt, a key regulator molecule that may underlie the fine tuning between proliferative and neuroplasticity changes induced by antidepressant drugs.

Treatment of first-episode non-affective psychosis: a randomized comparison of aripiprazole, quetiapine and ziprasidone over 1 year.

RATIONALE: Discontinuation of antipsychotic treatment at early phases increases the risk of poor adherence to maintenance drug therapy. Differences among antipsychotics in terms of effectiveness may determine a good adherence to treatment. OBJECTIVES: The aim of this study is to compare the clinical effectiveness of aripiprazole, ziprasidone and quetiapine in the treatment of first-episode schizophrenia spectrum disorders at 1 year. METHOD: From October 2005 to January 2011 a prospective, randomized, open-label study was undertaken. Two hundred two first-episode drug-naïve patients were randomly assigned to aripiprazole (N = 78), ziprasidone (N = 62), or quetiapine (N = 62) and followed up for 1 year. The primary effectiveness measure was all-cause of treatment discontinuation. In addition, an analysis based on intention-to-treat principle was conducted in the analysis for clinical efficacy. RESULTS: The overall dropout rate at 1 year was 13.37 %. The treatment discontinuation rate differed significantly between treatment groups (aripiprazole = 43.6 %, ziprasidone = 66.1 % and quetiapine = 82.3 %) (χ 2 = 22.545; p < 0.001). Insufficient efficacy in the group of quetiapine is the most important reason for differences in discontinuation rates between agents (χ 2 = 19.436; p < 0.001). The mean time to all-cause discontinuation was significantly different between groups (LogRank = 30.732 p < 0.001). The profile of extrapyramidal symptoms varies between treatments. Patients on ziprasidone were more likely to be prescribed antidepressants. CONCLUSIONS: First episode patients treated with quetiapine have a higher risk of treatment discontinuation at midterm due to insufficient efficacy. Establishing differences between SGAs may help clinicians on prescribing decision for treatment of individuals presenting with first-episode non-affective psychosis.

Serotonin 5-HT4 receptors: A new strategy for developing fast acting antidepressants?

The regulation of the activity of brain monoaminergic systems has been the focus of attention of many studies since the first antidepressant drug emerged 50 years ago. The search for novel antidepressants is deeply linked to the search for fast-acting strategies, taking into account that 2-4 weeks of treatment with classical antidepressant are required before clinical remission of the symptoms becomes evident. In the recent years several hypotheses have been proposed on the basis of the existence of alterations in brain synaptic plasticity in major depression. Recent evidences support a role for 5-HT4 receptors in the pathogenesis of depression as well as in the mechanism of action of antidepressant drugs. In fact, chronic treatment with antidepressant drugs appears to modulate, at different levels, the signaling pathway associated to 5-HT4 receptors, as well as their levels of expression in the brain. Moreover, several experimental studies have identified this receptor subtype as a promising new target for fast-acting antidepressant strategy: the administration of partial agonists of this receptor induces a number of responses similar to those observed after chronic treatment with classical antidepressants, but with a rapid onset of action. They include efficacy in behavioral models of depression, rapid desensitization of 5-HT1A autoreceptors, and modifications in the expression of several molecular markers of brain neuroplasticity. Although much work remains to be done in order to clarify the real therapeutic potential of these drugs, the evidences reviewed below support the hypothesis that 5-HT4 receptor partial agonists could behave as rapid and effective antidepressants.

Neural plasticity and proliferation in the generation of antidepressant effects: hippocampal implication.

It is widely accepted that changes underlying depression and antidepressant-like effects involve not only alterations in the levels of neurotransmitters as monoamines and their receptors in the brain, but also structural and functional changes far beyond. During the last two decades, emerging theories are providing new explanations about the neurobiology of depression and the mechanism of action of antidepressant strategies based on cellular changes at the CNS level. The neurotrophic/plasticity hypothesis of depression, proposed more than a decade ago, is now supported by multiple basic and clinical studies focused on the role of intracellular-signalling cascades that govern neural proliferation and plasticity. Herein, we review the state-of-the-art of the changes in these signalling pathways which appear to underlie both depressive disorders and antidepressant actions. We will especially focus on the hippocampal cellularity and plasticity modulation by serotonin, trophic factors as brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) through intracellular signalling pathways-cAMP, Wnt/ ß -catenin, and mTOR. Connecting the classic monoaminergic hypothesis with proliferation/neuroplasticity-related evidence is an appealing and comprehensive attempt for improving our knowledge about the neurobiological events leading to depression and associated to antidepressant therapies.

Aripiprazole, Ziprasidone and Quetiapine in the treatment of first-episode nonaffective psychosis: a 12-week randomized, flexible-dose, open-label trial.

BACKGROUND: Differences among antipsychotics in terms of effectiveness have turned out to be a topic of increasing research interest, although comparisons between the different second generation antipsychotics (SGAs) are scarce. We aimed to compare the clinical effectiveness in the short-term of Aripiprazole, Ziprasidone and Quetiapine in the treatment of first-episode schizophrenia-spectrum disorders. METHOD: From October 2005 to January 2011, a prospective, randomized, open-label study was undertaken. 202 first-episode drug-naïve patients were randomly assigned to Aripiprazole (N = 78), Ziprasidone (N = 62), or Quetiapine (N = 62) and followed-up for 3 months. The primary effectiveness measure was all-cause of treatment discontinuation. In addition, an analysis based on intention-to-treat populations was conducted in the analysis for clinical efficacy. RESULTS: The overall dropout rate at 3 months was small (13.86%). The treatment discontinuation rate differed significantly between treatment groups (Aripiprazole = 23.1%, Ziprasidone = 37.1% and Quetiapine = 61.3%) (χ(2) = 21.334; p < 0.001). Insufficient efficacy in the group of Quetiapine is the main reason for discontinuation rate differences (χ(2) = 20.223; p < 0.001). The mean time to all-cause discontinuation was significantly different between groups (LogRank = 23.467 p < 0.001). Aripiprazole and Quetiapine were associated with a greater depressive symptoms improvement (p = 0.043). The profile of side-effects varies between treatments. Patients on Quetiapine were less likely to be prescribed hypnotics. CONCLUSIONS: Patients treated with Quetiapine had a higher risk of treatment discontinuation in the short-term after a first episode due to insufficient efficacy. Establishing differences between SGAs may help clinicians in prescribing decisions for the treatment of individuals presenting with first-episode schizophrenia.

Aripiprazole, ziprasidone, and quetiapine in the treatment of first-episode nonaffective psychosis: results of a 6-week, randomized, flexible-dose, open-label comparison.

Differences among antipsychotics in effectiveness have turned out to be a topic of increasing research interest, although comparisons between the different second-generation antipsychotics are scarce. From October 2005 to March 2011, a prospective, randomized, open-label study comparing the effectiveness of aripiprazole, ziprasidone, and quetiapine in the short-term treatment of first-episode schizophrenia-spectrum disorders was undertaken. Two hundred two patients were randomly assigned to aripiprazole (n = 78), ziprasidone (n = 62), or quetiapine (n = 62) and followed up for 6 weeks. The primary effectiveness measure was all-cause of treatment discontinuation. In addition, an analysis based on per protocol populations was conducted in the analysis for clinical efficacy. The overall dropout rate at 6 weeks was small (6.4%). The treatment discontinuation rate differed significantly between treatment groups (aripiprazole, 15%; ziprasidone, 19%; and quetiapine, 35%; χ(2) = 8.529; P = 0.014). Insufficient efficacy in the group of quetiapine is the main reason for discontinuation rate differences (χ = 10.139; P = 0.006). The mean time to all-cause discontinuation was significantly different between the groups (log-rank, 12.783; P = 0.001). Quetiapine was associated with a greater depressive symptoms improvement than ziprasidone (P = 0.045). The rate of responders at 6 weeks differed between the groups (F = 6, 116; P = 0.047), with a higher rate of the responders with aripiprazole. The profile of adverse effects varies between the treatments. Patients on quetiapine were less likely to be prescribed concomitant medications. Treatment with quetiapine was associated with a higher risk of treatment discontinuation during treatment owing to insufficient efficacy. Differences in effectiveness between second-generation antipsychotics would determine their position in everyday clinical practice and could help physicians choose the more efficacious antipsychotics.

Long-term effect of haloperidol, olanzapine, and risperidone on plasma prolactin levels in patients with first-episode psychosis.

OBJECTIVE: The main goal of this study was to assess the long-term effect of haloperidol, olanzapine, and risperidone on serum prolactin levels in a naturalistically treated first-episode psychosis population. METHODS: Patients included in this study were drawn from a prospective, randomized, open-label clinical trial. Prolactin levels were measured in 110 patients with medication-naive first-episode psychosis at baseline, 3 months, and 1 year. RESULTS: A repeated-measures analysis of variance revealed a significant difference between treatments (F = 17.28, P < 0.001). At 1-year follow-up, most patients in the haloperidol and olanzapine arms had prolactin values that fell within the reference range. Patients treated with risperidone experienced a significant increase at 3 months resulting in prolactin levels above the reference range in 90% of men and 87% of women. The levels showed a tendency to decrease at 1 year, although still more than 70% of the values remained above the normative range. Sexual adverse drug reactions at 1 year assessed by the Udvalg for Kliniske Undersogelser scale showed that a higher percentage (39.3%) of patients had symptoms in the risperidone group compared to the olanzapine group (24%) or haloperidol group (20%), but the difference did not reach statistical significance (P = 0.281). CONCLUSION: Olanzapine and haloperidol treatments do not significantly affect serum prolactin levels at long term. After 1 year, elevated prolactin levels persist in most patients treated with risperidone.

Chronic treatment with the opioid antagonist naltrexone favours the coupling of spinal cord µ-opioid receptors to Gαz protein subunits.

Sustained administration of opioid antagonists to rodents results in an enhanced antinociceptive response to agonists. We investigated the changes in spinal µ-opioid receptor signalling underlying this phenomenon. Rats received naltrexone (120 µg/h; 7 days) via osmotic minipumps. The antinociceptive response to the µ-agonist sufentanil was tested 24 h after naltrexone withdrawal. In spinal cord samples, we determined the interaction of µ-receptors with Gα proteins (agonist-stimulated [(35)S]GTPγS binding and immunoprecipitation of [(35)S]GTPγS-labelled Gα subunits) as well as µ-opioid receptor-dependent inhibition of the adenylyl cyclase (AC) activity. Chronic naltrexone treatment augmented DAMGO-stimulated [(35)S]GTPγS binding, potentiated the inhibitory effect of DAMGO on the AC/cAMP pathway, and increased the inverse agonist effect of naltrexone on cAMP accumulation. In control rats, the inhibitory effect of DAMGO on cAMP production was antagonized by pertussis toxin (PTX) whereas, after chronic naltrexone, the effect became resistant to the toxin, suggesting a coupling of µ-receptors to PTX-insensitive Gα(z) subunits. Immunoprecipitation assays confirmed the transduction switch from Gα(i/o) to Gα(z) proteins. The consequence was an enhancement of the antinociceptive response to sufentanil that, in consonance with the neurochemical data, was prevented by Gα(z)-antisense oligodeoxyribonucleotides but not by PTX. Such changes in opioid receptor signalling can be a double-edged sword. On the one hand, they may have potential applicability to the optimisation of the analgesic effects of opioid drugs for the control of pain. On the other hand, they represent an important homeostatic dysregulation of the endogenous opioid system that might account for undesirable effects in patients chronically treated with opioid antagonists. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Modulation of neuroplasticity pathways and antidepressant-like behavioural responses following the short-term (3 and 7 days) administration of the 5-HT4 receptor agonist RS67333.

It has been recently suggested that activation of 5-HT4 receptors might exert antidepressant-like effects in rats after 3 d treatment, suggesting a new strategy for developing faster-acting antidepressants. We studied the effects of 3 d and 7 d treatment with the 5-HT4 receptor partial agonist RS67333 (1.5 mg/kg.d) in behavioural tests of chronic efficacy and on neuroplastic-associated changes, such as adult hippocampal neurogenesis, expression of CREB, BDNF, ß-catenin, AKT and 5-HT4 receptor functionality. RS67333 treatment up-regulated hippocampal cell proliferation, ß-catenin expression and pCREB/CREB ratio after 3 d treatment. This short-term treatment also reduced immobility time in the forced swim test (FST), together with a partial reversion of the anhedonic-like state (sucrose consumption after chronic corticosterone). Administration of RS67333 for 7 d resulted in a higher increase in the rate of hippocampal cell proliferation, a significant desensitization of 5-HT4 receptor-coupled adenylate cyclase activity and a more marked increase in the expression of neuroplasticity-related proteins (BDNF, CREB, AKT): these changes reached the same magnitude as those observed after 3 wk administration of classical antidepressants. Consistently, a positive behavioural response in the novelty suppressed feeding (NSF) test and a complete reversion of the anhedonic-like state (sucrose consumption) were also observed after 7 d treatment. These results support the antidepressant-like profile of RS67333 with a shorter onset of action and suggest that this time period of administration (3-7 d) could be a good approximation to experimentally predict the onset of action of this promising strategy.

New strategies in the development of antidepressants: towards the modulation of neuroplasticity pathways.

Over the past five decades, the pharmacological treatment of depression has been based on the pathophysiological hypothesis of a deficiency in monoamines, mainly serotonin and noradrenaline. Antidepressant prescribed today, all of them designed to enhance central monoaminergic tone, present several important limitations, including a 2-5 weeks response lag and also a limited clinical efficacy. As it is increasingly evident that the abnormalities associated to depression go beyond monoamines, the development of better antidepressants will depend on the identification and understanding of new cellular targets. In this regard, much evidence supports a role for cellular and molecular mechanisms of neuroplasticity, including neurotrophic inputs, in mood disorders, in parallel with the biological features associated to stress conditions. In order to illustrate the possible relevance of neuroplasticity-related pathways for the therapy of depressive states, we here review the biological evidence supporting some therapeutic strategies in a very initial phase of development (modulation of the Wnt/GSK-3ß/ß-catenin pathway, potentiation of endocannabinoid activity, agonism of 5-HT(4) receptors), which involve modulation of downstream mechanisms and neuroplasticity circuits. These strategies also show the existence of mixed mechanisms of action, constituting a nexus between the "classic" aminergic theory and the "new" neuroplasticity hypothesis.

α2-Adrenoceptor functionality in postmortem frontal cortex of depressed suicide victims.

BACKGROUND: Alterations in brain density and signaling associated with monoamine receptors are believed to play a role in depressive disorders. This study evaluates the functional status of α2(A)-adrenoceptors in postmortem frontal cortex of depressed subjects. METHODS: G-protein activation and inhibition of adenylyl cyclase (AC) activity induced by the α2-adrenoceptor agonist UK14304 were measured in triplicate in samples from 15 suicide victims with an antemortem diagnosis of major depression and 15 matched control subjects. RESULTS: Basal [³5S] guanosine γ thio-phosphate (GTPγS) binding and cyclic adenosine monophosphate accumulation did not differ between groups. In depressed victims, an increase in [³5S] GTPγS binding potency (EC50 = .58 µmol/L vs. EC50 = 3.31 µmol/L; p < .01; depressed vs. control) and a significant reduction in the maximal inhibition of AC activity (I(max) = 27 ± 4% vs. I(max) = 47 ± 5%; p < .01) were observed after incubation with the α(2)-adrenoceptor agonist UK14304. No differences were found between antidepressant-free and antidepressant-treated subjects. A significant relationship between EC50 values for [³5S] GTPγS and I(max) values for AC assay was found (n = 30; r = -.43; p < .05). CONCLUSIONS: The dual regulation of α(2A)-adrenoceptor signaling pathways raises the possibility that factors affecting the G-protein cycle and/or selective access of Gα(i/o)-protein to AC might be relevant to receptor abnormalities in depression, providing further support for the involvement of α2(A)-adrenoceptors in the pathogenesis of depression.

UGT2B7_-161C>T polymorphism is associated with lamotrigine concentration-to-dose ratio in a multivariate study.

Lamotrigine (LTG) is metabolized by UGT1A4 but UGT2B7 also contributes to its glucuronidation. The aim of this study was to determine whether UGT2B7_- 161C>T and UGT2B7_372A>G polymorphisms contribute to the intersubject variability in LTG concentration-to-dose ratio (LTG-CDR) in epileptic patients. Fifty-three white epileptic patients attending the Neuropediatric and Neurology Services at the Marqués de Valdecilla University Hospital, in whom LTG serum concentration was to be measured for pharmacokinetic monitoring, were selected according to predefined criteria for LTG-CDR evaluation. All patients had at least one steady-state LTG serum concentration obtained before the first dose in the morning. Patients were classified in 3 groups of comedication: (1) LTG in combination with metabolism-inducer anticonvulsants (n = 22), (2) LTG in combination with valproate (n = 13), and (3) LTG as monotherapy (n = 16) or in combination with valproate and inducers (n = 2). Genotypes were determined by Applied Biosystems Genotyping Assays with TaqMan probes. A significant association was found between LTG-CDR and UGT2B7_-161C>T polymorphism (P = 0.021) when patient age and concomitant antiepileptic drugs were taken into account. Comedication explained 70% of the LTG-CDR variability, patient age 24%, and UGT2B7_-161C>T 12%. In contrast, a significant association between LTG-CDR and this polymorphism was not found in the bivariate study when age and comedication groups were not considered. A significant association between UGT2B7_372A>G and LTG-CDR was not found in the bivariate or the multivariate studies. UGT2B7_-161C>T polymorphism is significantly associated with LTG-CDR when comedication with other antiepileptic drugs and patient age are taken into account in a multivariate analysis.