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To separate the direct pharmacological effects of cocaine from those associated with active drug self-administration we employed a yoked control-operant paradigm and investigated the expression of well established markers of the rapid action of cocaine, i.e. the inducible early genes Arc and Zif268 and trophic factors, i.e. brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (FGF-2), in rats after a single intravenous (i.v.) cocaine self-administration session. Animals self-administering cocaine (SA, 0.25 mg/0.1 ml saline per infusion, 2-h session) did more active lever-presses than yoked-cocaine (YC) and yoked-vehicle (YV) animals. This goal-oriented behaviour was accompanied by a selective increase in Arc mRNA levels in the medial prefrontal cortex (mPFC). There were no changes in the expression of the other genes in this brain region. mRNA levels of Arc and Zif268 in striatum and Zif268 in the nucleus accumbens markedly increased both in SA and YC animals; but there was no change in the expression of FGF-2 and BDNF. No changes were observed in hippocampus, hypothalamus, frontal cortex, and midbrain in SA and YC animals compared to YV animals in any of the genes. These findings demonstrate that a single session of cocaine i.v. self-administration is sufficient to shape rat behaviour towards goal-directed behaviours and selectively up-regulate Arc expression in mPFC (of SA animals), providing the first evidence that the mPFC's function is already profoundly influenced by the first voluntary cocaine exposure.

We found that, in the striatum, acute injections of the first generation antipsychotic (FGA) haloperidol or the second generation antipsychotic (SGA) olanzapine enhanced Arc mRNA levels, however such induction persisted for at least 2 h in haloperidol-treated rats whereas it waned as early as 1 h after olanzapine injection. Conversely, repeated injections led to a persistent decrease of striatal Arc gene expression, regardless of the agent examined. In the frontal cortex, acute injection of both antipsychotics caused a reduction of Arc mRNA levels which persisted for at least 2 h. Following repeated treatment, olanzapine reduced Arc mRNA levels 2 h, but not 24 h, post-treatment whereas haloperidol was ineffective. Of note, the SGA quetiapine regulated the Arc gene expression similarly to olanzapine. Given the particular nature of Arc, our findings show its fine tuning following antipsychotic administration to be highly dependent on the length of the treatment and on the brain region investigated and suggest that antipsychotic drugs affect this marker of neuronal activity differently.

Historically, pharmacotherapy for schizophrenia was mainly focused on finding drugs to treat psychotic symptoms only, without addressing other crucial domains of the disorder such as cognitive impairments. As a result, these domains have remained undertreated. In this review, we discuss recent preclinical research efforts, including investigation of synaptic mechanisms as well as intracellular signalling pathways and mechanisms involved in neuroplasticity and cell resilience, that may represent new mechanisms participating in the pathogenesis of schizophrenia, particularly at the level of the prefrontal cortex and hippocampus, and that might lead to the development of drugs that can counteract, at least partially, the cognitive impairments typical of schizophrenia.

Rationale: Therapeutic efficacy of antidepressant drugs appears to be related to their ability in producing neuroadaptive changes that restore normal brain function. Activity-regulated cytoskeletal associated protein (Arc) is an effector immediate early gene that plays a fundamental role in activity-dependent neural plasticity in corticolimbic brain regions and has been implicated in the modulation of several functions known to be profoundly perturbed in depressive states., Objective: In the present study, we investigated transcriptional and translational changes of Arc in response to acute or chronic treatment with the novel antidepressant duloxetine., Results: Although a limited increase of Arc messenger RNA (mRNA) levels was found in some structures after acute antidepressant administration, a marked up-regulation of its gene expression was found after chronic treatment, primarily at the level of frontal cortex. The changes observed after prolonged duloxetine administration strongly correlates with those previously reported on brain-derived neurotrophic factor mRNA levels Calabrese et al. (Neuropsychopharmacol 32:2351-2359, 2007). In addition, we found an anatomical-specific influence of chronic duloxetine on stress-dependent Arc modulation, which was limited to the frontal cortex., Conclusions: We suggest that these neuroadaptive changes, among others, might contribute to the normalization of neuroplastic defects associated with mood disorders.

Repeated antipsychotic treatment may produce adaptive changes ranging from cytoarchitectural rearrangements to synaptic modifications that might contribute to clinical improvement. We performed a prolonged treatment (2 wk) with the first-generation antipsychotic (FGA) haloperidol (1 mg/kg) and the second-generation antipsychotic (SGA) olanzapine (2 mg/kg twice daily) and analysed the expression of the polysialylated form of neural cell adhesion molecule (PSA-NCAM) in rat hippocampus and prefrontal cortex via immunohistochemistry. We found a regional- and drug-selective increase of PSA-NCAM expression in prefrontal cortex of olanzapine-treated rats with no effects in hippocampus; conversely, haloperidol did not produce a change in either brain region. Our findings reveal a possible role for PSA-NCAM in the mechanism of action of the SGA olanzapine adding complexity as well as specificity to the molecular changes set in motion by this drug.

Background: Recent rodent studies reported that antidepressant treatments affect the expression of brain-derived neurotrophic factor (BDNF) mRNA in a way that is dependent on treatment duration, by selective modulation of different BDNF transcripts. However, no data are available for the human BDNF gene. We studied the effect of different antidepressants on BDNF mRNA expression in human neuroblastoma SH-SY5Y cells., Results: Cultured cells were treated with the antidepressants fluoxetine, reboxetine and desipramine for different time lengths (6, 24, 48 hours). Expression of total BDNF mRNA was analyzed by reverse transcription PCR and levels of different BDNF transcripts were detected by hemi-nested PCR with specific primers. Short-term treatment (6 hours) with reboxetine or desipramine reduced total BDNF, whereas long-term treatment (48 hours) significantly increased total BDNF mRNA levels. These changes were accounted for by differential regulation of BDNF IV and VIa/b transcripts. Fluoxetine showed no significant effects., Conclusion: This is the first study showing biphasic changes in the expression of total and specific BDNF transcripts in human cells following antidepressant treatments. These findings suggest that biphasic induction of BDNF by antidepressants could be a feature common to rodents and humans and encourage the use of SH-SY5Y cells as a tool for investigation of drug effects on human genes.

Antipsychotics are the mainstay for the treatment of schizophrenia. Although these drugs act at several neurotransmitter receptors, they are expected to elicit different neuroadaptive changes at structures relevant for schizophrenia. Because glutamatergic dysfunction plays a role in the pathophysiology of schizophrenia, we focused our analysis on glutamatergic neurotransmission after repeated treatment with antipsychotic drugs. Rats were exposed to a 2-week pharmacological treatment with the first generation antipsychotic haloperidol and the second generation antipsychotic olanzapine. By using Western blot and immunoprecipitation techniques, we investigated the expression, trafficking, and interaction of essential components of glutamatergic synapse in rat prefrontal cortex. Prolonged treatment with haloperidol, but not olanzapine, dynamically affects glutamatergic synapse by selectively reducing the synaptic level of the obligatory N-methyl-d-aspartate (NMDA) subunit NR1, the regulatory NMDA subunit NR2A, and its scaffolding protein postsynaptic density 95 as well as the trafficking of subunit 1 of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor to the membrane. In addition, haloperidol alters total as well as phosphorylated levels of calcium calmodulin kinase type II at synaptic sites and its interaction with the regulatory NMDA subunit NR2B. Our data suggest that the glutamatergic synapse is a vulnerable target for prolonged haloperidol treatment. The global attenuation of glutamatergic function in prefrontal cortex might explain, at least in part, the cognitive deterioration observed in patients treated with haloperidol.

Evidence exists that schizophrenia is characterized by deficits in cell-cell communication and information processing. In the present study, we used the phencyclidine (PCP) animal model of schizophrenia to investigate possible defects in intracellular signaling proteins involved in neuroplasticity. Western Blot analysis has been performed to determine total and phospho-protein levels of extracellular signal-regulated kinases 1/2 (ERK1/2), type II calcium/calmodulin-dependent protein kinase (alphaCaMKII) and cAMP-response element binding protein (CREB) in prefrontal cortex (PFC) and hippocampus (HIP) of rat chronically treated with PCP, whereas their mRNA levels were determined by real time RT-PCR. We found reduced levels of P-ERK1/2, P-alphaCaMKII and P-CREB in prefrontal cortex of PCP-treated animals when compared to controls, whereas no effects were observed on total protein or mRNA levels. Conversely, no significant changes were detected on protein levels or mRNA expression in hippocampus. Given the role of ERK1/2, alphaCaMKII and CREB in neuroplastic mechanisms and cell communication, our data suggest that their decreased activation following chronic PCP administration can contribute to cortical defects occurring in schizophrenia, and may therefore represent potential targets for pharmacological intervention.

Rationale: Our laboratory has previously demonstrated that the expression of basic fibroblast growth factor (FGF-2), a protein involved in survival and maintenance of several cell phenotypes as well as in synaptic plasticity, is modulated by stress (Molteni et al., Brain Res Rev 37:249-258, 2001; Fumagalli et al., Neurobiol Dis 20:731-737, 2005) and cocaine (Fumagalli et al., J Neurochem 96:996-1004, 2006)., Objectives: Since it is widely recognized that stress influences drug seeking, we decided to investigate whether stress, acute or repeated, could influence the changes in FGF-2 gene expression brought about by cocaine., Results: Our data demonstrate that stress and cocaine interact to produce significant changes on FGF-2 expression in rat prefrontal cortex and striatum. In prefrontal cortex, our experiments demonstrated that a single exposure to stress potentiated cocaine-induced FGF-2 elevation, whereas prolonged stress prevented the modulation of the trophic factor in response to cocaine. In striatum, the magnitude of cocaine-induced FGF-2 response is enhanced by repeated stress, whereas no interaction was observed when acute stress and single exposure to cocaine were combined., Conclusions: Our findings demonstrate that stress interacts with cocaine to alter the pattern of FGF-2 expression in a way that depends on whether stress is acute or chronic and in a regionally selective fashion. These results identify a potential molecular target through which stress alters cellular sensitivity to cocaine and might prove useful in understanding the mechanisms underlying brain vulnerability to stress.

Acute lesions of the spinal cord lead to dramatic changes in neuronal function. In the present study, we examined the possible involvement of neurotrophic factors in the action of the drug of choice for the treatment of such an emergency, i.e. the glucocorticoid methylprednisolone is compared to erythropoietin, a cytokine recently shown to markedly shorten the time necessary for motor recovery following injury [Gorio, A., Gokmen, N., Erbayraktar, S., Yilmaz, O., Madaschi, L., Cichetti, C., Di Giulio, A.M., Vardar, E., Cerami, A., Brines, M., 2002. Recombinant human erythropoietin counteracts secondary injury and markedly enhances neurological recovery from experimental spinal cord trauma. Proc. Natl. Acad. Sci. 99, 9450-9455]. We found that methylprednisolone reduces the lesion-enhanced Nerve Growth Factor (NGF) mRNA levels 3 h after injury in the trauma epicenter and caudal section of the cord whereas erythropoietin reinforced the NGF gene expression. Three days after the occurrence of the lesion, erythropoietin, but not methylprednisolone, significantly up-regulated the NGF gene expression both caudally and rostrally to the lesion site, an effect that, based on the chemo-attractant properties of neurotrophin, might facilitate the growth of injured axons toward NGF-rich sites and contribute to the enhancement of the regenerative process. The differences between the effects of methylprednisolone and erythropoietin dissipate 7 days after the lesion when they both enhance NGF mRNA levels at the epicenter. These data show that methylprednisolone and erythropoietin display a different pattern of activation of the neurotrophin NGF which is strictly dependent on the portion of the cord examined and the time elapsed from the injury. Based on our results, we suggest that the higher increase of NGF expression mediated by erythropoietin soon after the injury might explain, at least in part, the improved recovery of motor functions produced by erythropoietin compared to methylprednisolone and saline.

Finding an effective therapy to treat chronic neurodegenerative disorders still represents an unmet and elusive goal, mainly because so many pathogenic variables come into play in these diseases. Recent emphasis has been placed on the role of neurotrophic factors in the aetiology of such disorders because of their role in the survival of different cell phenotypes under various adverse conditions, including neurodegeneration.This review summarizes the current status and the efforts to treat neurodegenerative disorders by the exogenous administration of neurotrophic factors in an attempt to replenish trophic supply, the paucity of which may contribute to the development of the illness. Although promising results have been seen in animal models, this approach still meets disparate and often insurmountable problems in clinical settings, presumably related to the unique nature of the human being.

The hypotheses on the pathophysiology of depression/mood disorders and on antidepressant mechanisms have greatly changed in recent years. The classical monoamine hypothesis was revealed to be simplistic, in that it could not explain the temporal delay in the therapeutic action of antidepressants. Converging lines of evidence have shown that adaptive changes in the several mechanisms of neuroplasticity are likely to be the cellular and molecular correlates of therapeutic effect. In this article, several mechanisms of neuroplasticity are analyzed in relation to the mechanism of antidepressants, ranging from changes in gene expression (including neurotrophic mechanisms), to synaptic transmission and plasticity, and neurogenesis. We propose that the current version of the hypothesis of antidepressant mechanism simply be called the "hypothesis of neuroplasticity". In the final section, we also briefly review the main current novel strategies in the pharmacology of depression and the new putative targets for antidepressants, with particular emphasis on nonmonoaminergic mechanisms.

Changes in synaptic plasticity are involved in pathophysiology of depression and in the mechanism of antidepressants. Ca(2+)/calmodulin (CaM) kinase II, a protein kinase involved in synaptic plasticity, has been previously shown to be a target of antidepressants. We previously found that antidepressants activate the kinase in hippocampal neuronal cell bodies by increasing phosphorylation at Thr(286), reduce the kinase phosphorylation in synaptic membranes, and in turn its phosphorylation-dependent interaction with syntaxin-1 and the release of glutamate from hippocampal synaptosomes. Here, we investigated the chronic effect of different antidepressants (fluoxetine, desipramine, and reboxetine) on the expression and function of the kinase in distinct subcellular compartments in order to dissect the different kinase pools affected. Acute treatments did not induce any change in the kinase. In total tissue extracts chronic drug treatments induced activation of the kinase; in hippocampus (HC), but not in prefrontal/frontal cortex, this was partially accounted for by increased Thr(286) phosphorylation, suggesting the involvement of different mechanisms of activation. In synaptosomes, all drugs reduced the kinase phosphorylation, particularly in HC where, upon fractionation of the synaptosomal particulate into synaptic vesicles and membranes, we found that the drugs induced a redistribution and differential activation of the kinase between membranes and vesicles. Furthermore, a large decrease in the level and phosphorylation of synapsin I located at synaptic membranes was consistent with the observed decrease of CaM kinase II. Overall, antidepressants induce a complex pattern of modifications in distinct subcellular compartments; at presynaptic level, these changes are in line with a dampening of glutamate release.

Phencyclidine (PCP) induces a form of psychosis that mimics naturally occurring schizophrenia in the most relevant domains of the psychopathology. In this report, we investigated the effect of chronic treatment with PCP on expression and RNA editing of alpha-amino-propionic acid (AMPA) and kainate (KA) glutamate receptor (GluR), in the rat prefrontal cortex and the hippocampus. We found that chronic, but not acute, PCP treatment decreased GluRs expression in the rat prefrontal cortex but not in the hippocampus. In particular, the mRNA coding for GluR2 and GluR3 subunits were reduced by 50%, whereas those coding for KA GluR5 and GluR6 were decreased by 30%. In addition, we observed a decrease of the editing levels of the R/G site in the flop form of both GluR2 and GluR3 and a significant increase in the editing level of GluR6 Q/R site. The variation in the editing level of the R/G sites suggests that chronic PCP treatment induced the formation of glutamate receptor subunits with slower resensitization kinetics and, with respect to kainate receptors, an increase in the Q/R editing level might generate receptor channels with a lower permeability to cations. Combining all the data, it can be inferred that the PCP treatment induced a specific and site-selective reduction of glutamatergic neurotransmission in the prefrontal cortex but not in the hippocampus.

In this report we investigated the modulation of the neurotrophin brain-derived neurotrophic factor (BDNF) following single or repeated injections with cocaine. Dose-response experiments revealed that a single dose of cocaine (5 mg/kg) is sufficient to upregulate BDNF mRNA levels selectively in rat prefrontal cortex 2 h after the injection, an effect that persists at least for 24 h and is paralleled by enhanced expression of mature (m)BDNF protein. Five consecutive injections of the psychostimulant (5 mg/kg) potentiate the increase of BDNF mRNA levels 2 h after the last treatment, presumably as a result of the enhancement of cAMP response element-binding protein (CREB) phosphorylation, an effect that vanishes 72 h later. Conversely, precursor (pro-) and mBDNF protein forms were markedly reduced 2 h and 72 h post-injection in the prefrontal cortex. Interestingly, in the striatum we found that repeated cocaine injection increased pro-BDNF levels without altering the mature form of the neurotrophin. Our results suggest that cocaine differently affects BDNF transcription and translation in a region-selective manner, but might also alter neurotrophin processing. These data further support the notion that the corticostriatal network is highly vulnerable to the effects of cocaine, and suggest that abnormal regulation of BDNF expression could contribute, at least in part, to the functional defects observed in drug abusers.

There is growing evidence that brain-derived neurotrophic factor (BDNF) can be relevant to mood disorders and that modulation of its biosynthesis following prolonged antidepressant treatment may contribute to neuroplastic changes required for clinical response. In the present study, we investigated the effects of the novel antidepressant duloxetine on BDNF in the rat brain. Duloxetine is a serotonin-norepinephrine reuptake inhibitor that differs from other antidepressants by virtue of its balanced potency on both neurotransmitter systems. We found that chronic, but not acute, treatment with duloxetine produces a robust increase of exon V BDNF mRNA levels in frontal cortex when the animals were killed 1 or 24 h after the last administration. The expression of the neurotrophin was also increased in other cortical subregions, but not in the hippocampus. We also found that the increased expression of BDNF in frontal cortex was mainly sustained by enhanced mRNA levels for exons I and III, whereas the expression of exon IV was reduced. Protein analysis in different subcellular fractions showed that chronic treatment with duloxetine, but not with the prototypical SSRI fluoxetine, reduced mature BDNF in the cytosol, but markedly increased its levels in the crude synaptosomal fraction. Our data suggest that chronic treatment with the novel antidepressant duloxetine not only produces a marked upregulation of BDNF mRNA and protein, but may also affect the subcellular redistribution of the neurotrophin. These changes might improve synaptic plasticity and cognitive function that are defective in depressed subjects.

Sleep disturbances are often associated with depression and mood disorders, and certain manipulations of the sleep-wake cycle are effective as therapeutic interventions in the treatment of depression. Dysregulated circadian rhythms are thereby considered as causal. Circadian rhythms in mammals are mainly regulated by a core biological clock, located in the hypothalamic suprachiasmatic nucleus; its pacemaker activity is regulated by light and nonphotic modulatory pathways, and the driving mechanisms are serotonergic input from the raphe and the hormone melatonin originating from the pineal gland. In line, the concentration of brain serotonin and the levels of 5-HT2C receptors are high and highly expressed there. Agomelatine, a novel antidepressant drug with proven clinical efficacy in major depressive disorder, has a unique mechanism of action; it acts as an agonist at melatonergic MT1 and MT2 receptors and as an antagonist at 5-HT2C receptors. In animals, agomelatine was shown to increase noradrenaline and dopamine (but not serotonin) in the frontal cortex, to resynchronize the sleep-wake cycle in models with disrupted circadian rhythms, and to exhibit a clear antidepressant effect in various animal models of depression. On the basis of the functional relationship between melatonergic and serotonergic signaling in the suprachiasmatic nucleus, and given agomelatine's affinity at melatonergic and 5-HT2C receptors, the therapeutic efficacy of the drug may be due to the potential synergy of its action at these different receptors.

Recent findings suggested a role for soluble amyloid-beta (Abeta) peptides in Alzheimer's disease associated cognitive decline. We investigated the action of soluble, monomeric Abeta(1-40) on CaM kinase II, a kinase involved in neuroplasticity and cognition. We treated organotypic hippocampal cultures short-term (up to 4h) and long-term (5 days) with Abeta(1-40) (1nM-5microM). Abeta did not induce cell damage, apoptosis or synaptic loss. Short-term treatment down-regulated enzymatic activity of the kinase, by reducing its Thr(286) phosphorylation. In contrast, long-term treatment (1nM-microM) markedly and significantly up-regulated enzymatic activity, with peak stimulation at 10nM (three-fold). Up-regulation of activity was associated with increased expression of the alpha-isoform of CaM kinase II, increased phosphorylation at Thr(286) (activator residue) and decreased phosphorylation at Thr(305-306) (inhibitory residues). We investigated the effect of glutamate on CaM kinase II following exposure to 1 or 10nM Abeta(1-40). As previously reported, glutamate increased CaM kinase II activity. However, the glutamate effect was not altered by pretreatment of slices with Abeta. Short- and long-term Abeta treatment showed opposite effects on CaM kinase II, suggesting that long-term changes are an adaptation to the kinase early down-regulation. The marked effect of Abeta(1-40) on the kinase suggests that semi-physiological and slowly raising peptide concentrations may have a significant impact on synaptic plasticity in the absence of synaptic loss or neuronal cell death.

Lithium is widely used in the treatment of bipolar disorder, although its mechanism of action is not fully clear. This study was undertaken to assess the effects of prolonged lithium administration on cAMP responsive element-binding protein (CREB) phosphorylation and CaM kinase IV (CaMKIV), one of the main kinases phosphorylating CREB in neurons following synaptic activation. CREB total protein expression and phosphorylation (Ser133), as well as CaMKIV enzymatic activity, phosphorylation of Thr196 (the activator residue) and kinase expression level were assessed in total homogenates and nuclei from the hippocampus and prefrontal/frontal cortex following 5 wk lithium treatment. Whereas no significant effects were found in prefrontal/frontal cortex, lithium administration reduced CREB phosphorylation and at the same time down-regulated CaMKIV (enzymatic activity, phospho-Thr196 and protein expression level) in cell nuclei from the hippocampus. These data suggest for the first time the involvement of CaMKIV in the mechanism of action of lithium.

Background: Basic fibroblast growth factor (FGF2) plays a crucial role during the development of the cerebral cortex. Mice with a knockout of the FGF2 gene have a reduced number of glutamatergic neurons within the deep layers of the cerebral cortex., Methods: We used molecular and behavioral analyses to investigate possible alterations in corticostriatal function in FGF2 -/- mice., Results: We found that FGF2 deficiency leads to decreased expression of presynaptic markers of integrity for glutamatergic fibers in the striatum, namely the membrane excitatory amino acid transporter 3 (EAAT3) and the vesicular glutamate transporter 1 (VGLUT1). The reduction of corticostriatal glutamatergic function in FGF2 -/- mice is associated with enhanced locomotor activity in a novel environment and increased responsiveness to dopaminergic drugs, such as cocaine or amphetamine. The behavioral alterations of FGF2 -/- can be normalized by injection of a low dose of the dopaminergic agonist apomorphine (.1 mg/kg) that reduces dopamine release by acting on presynaptic receptors., Conclusions: Our data demonstrate that FGF2 -/- mice have an increased tone and responsiveness of the dopaminergic system and suggest that these animals might represent a model to study disorders that are characterized by an imbalance between glutamatergic and dopaminergic neurotransmission.

Previous evidences showed that, besides noradrenaline (NA) and 5-hydroxytryptamine (5-HT), glutamate transmission is involved in the mechanism of action of antidepressants (ADs), although the relations between aminergic and glutamatergic systems are poorly understood. The aims of this investigation were to evaluate changes in the function of glutamate AMPA and NMDA receptors produced by acute and chronic administration of the two ADs reboxetine and fluoxetine, selective inhibitors of NA and 5-HT uptake, respectively. Rats were treated acutely (intraperitoneal injection) or chronically (osmotic minipump infusion) with reboxetine or fluoxetine. Isolated hippocampal nerve endings (synaptosomes) prepared following acute/chronic treatments were labelled with [(3)H]NA or [(3)H]5-HT and [(3)H]amine release was monitored during exposure in superfusion to NMDA/glycine, AMPA or K(+)-depolarization. Acute and chronic reboxetine reduced the release of [(3)H]NA evoked by NMDA/glycine or by AMPA. The NMDA/glycine-evoked release of [(3)H]NA was also down-regulated by chronic fluoxetine. Only acute, but not chronic, fluoxetine inhibited the AMPA-evoked release of [(3)H]5-HT. The release of [(3)H]NA and [(3)H]5-HT elicited by K(+)-depolarization was almost abolished by acute reboxetine or fluoxetine, respectively, but recovered during chronic ADs administration. ADs reduced NMDA receptor-mediated releasing effects in noradrenergic terminals after acute and chronic administration, although by different mechanisms. Chronic treatments markedly reduced the expression level of NR1 subunit in synaptic membranes. The noradrenergic and serotonergic release systems seem to be partly functionally interconnected and interact with glutamatergic transmission to down-regulate its function. The results obtained support the view that glutamate plays a major role in AD activity.

It is well accepted that adverse life events occurring early in development may alter the correct program of brain maturation leading to enhanced vulnerability to neuropsychiatric disorders. It has recently been demonstrated that prenatal exposure to the cannabinoid receptor 1 agonist (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinyl-methyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone (WIN 55,212-2) produces memory deficit in adulthood, an effect associated with a reduced functionality of the glutamatergic system. The aim of our study was to identify molecular changes produced by prenatal exposure to WIN 55,212-2 that might contribute to late disruption in synaptic plasticity and cognition. For this purpose, WIN 55,212-2 was injected in pregnant wistar rats from gestation day 5 to 20 and a detailed analysis of the levels of the neurotrophin brain-derived neurotrophic factor (BDNF) as well as of the signaling molecules extracellular signal-regulated kinase (ERK)1/2 and alpha-calcium/calmodulin-dependent protein kinase II (alpha-CaMKII) was carried out in adult offspring. We found that exposure to WIN 55,212-2 significantly reduced BDNF levels in hippocampus and frontal cortex. This effect was associated with decreased activation of pathways linked to neurotrophin and glutamate receptor signaling. In particular, prenatal cannabinoid treatment reduced the phosphorylated levels of ERK1/2 in selected subcellular compartments of hippocampus, frontal and prefrontal cortex, whereas no changes were observed in the total levels of these proteins. Furthermore, a robust reduction of total and phospho-alpha-CaMKII was found in the hippocampus of rats prenatally exposed to WIN 55,212-2. In summary, the present data suggest that deficits of BDNF levels and signaling through ERK1/2 and alpha-CaMKII might contribute to cognitive and neuroplastic defects associated with prenatal exposure to cannabinoids.

Development represents a critical moment for shaping adult behavior and may set the stage to disease vulnerability later in life. There is now compelling evidence that stressful experiences during gestation or early in life can lead to enhanced susceptibility for mental illness. In this paper we review the data from experimental studies aimed at investigating behavioral, hormonal, functional and molecular consequences of exposure to stressful events during prenatal or early postnatal life that might contribute to later psychopathology. The use of the newest methodology in the field and the intensive efforts produced by researchers have opened the possibility to reveal the complex, finely tuned and previously unappreciated sets of molecular interactions between different factors that are critical for neurodevelopment thus leading to important discoveries regarding perinatal life. The major focus of our work has been to revise and discuss data from animal studies supporting the role of neuronal plasticity in the long-term effects produced by developmental adversities on brain function as well as the possible implications for disease vulnerability. We believe these studies might prove useful for the identification of novel targets for more effective pharmacological treatments of mental illnesses.

We provide evidence that cocaine evokes short- and long-lasting increases in activity-regulated cytoskeletal-associated protein (Arc) expression after a finely tuned, time-dependent and regional-selective expression profile. Acute experiments revealed that cocaine up-regulates Arc expression primarily in striatum and prefrontal cortex through a dopamine D1-dependent mechanism and a combination of D1- and D2-dependent mechanisms, respectively. Aside from cocaine-dependent Arc elevation, we show for the first time that D1 and D2 receptors tonically regulate basal Arc expression following a regional-selective profile. As opposed to the effects of a single cocaine injection on Arc expression, which dissipate within 24 h, subchronic (five daily injections) or chronic (14 daily injections) cocaine administration, with animals sacrificed hours or days after the last treatment, demonstrated that Arc expression is still up-regulated long after treatment cessation, suggesting that adaptive changes have been set in motion by the prolonged administration of the psychostimulant. In summary, our findings are the first to demonstrate that repeated exposure to cocaine leads to long-lasting dysregulation of Arc expression in the corticostriatal network, thus establishing a molecular basis to explain, at least partially, the impaired synaptic transmission caused by cocaine abuse at this level. Furthermore, given the role exerted by Arc in cytoarchitectural rearrangements, it is conceivable to speculate that it mediates changes in synaptic connectivity brought about by cocaine. Our findings thus pinpoint this molecule as a neuropathological underpinning and molecular bridge that connects short- and long-term neuronal modifications associated with cocaine abuse.

During the last few years several studies have highlighted the possibility that major depression can be characterized by a general reduction in brain plasticity and an increased vulnerability under challenging situations. Such dysfunction may be the consequence of reduced expression and function of proteins important for neuroplasticity such as brain-derived neurotrophic factor (BDNF). On this basis, by using a sensitive non-radioactive in-situ hybridization, we evaluated the effects of a chronic treatment with fluoxetine on BDNF expression within rat dopaminergic regions. In fact, besides the well-established role of the hippocampus, increasing evidence indicates that other brain regions may be involved in the pathophysiology of depression and consequently be relevant for the therapeutic action of antidepressant drugs. Our results indicate that 3 wk of fluoxetine administration up-regulates BDNF mRNA levels selectively within structures belonging to the meso-cortico-limbic pathway. The expression of the neurotrophin is significantly increased in the ventral tegmental area, prefrontal cortex, and shell region of the nucleus accumbens, whereas no changes were detected in the substantia nigra and striatum. Moreover, in agreement with previous studies, fluoxetine increased BDNF mRNA levels in the hippocampus, an effect that was limited to the cell bodies without any change in its dendritic targeting. These data show that chronic treatment with fluoxetine increases BDNF gene expression not only in limbic areas but also in dopaminergic regions, suggesting that such an effect may contribute to improve the function of the dopaminergic system in depressed subjects.

Background: Several reports have shown that the glutamatergic system is involved in both the pathogenesis of affective and stress-related disorders and in the action of antidepressant drugs. In particular, antidepressant treatment was shown to modulate expression and function of ionotropic glutamate receptors, to inhibit glutamate release and to restore synaptic plasticity impaired by stress., Methods: We analyzed the mRNA expression and RNA editing of alpha-amino-propionic-acid (AMPA) and kainate (KA) receptor subunits, in the pre-frontal/frontal cortex (P/FC) and hippocampus (HI) of rats chronically treated with three different drugs: the selective serotonin (5-HT) reuptake inhibitor fluoxetine, the selective noradrenaline (NA) reuptake inhibitor reboxetine and the tricyclic antidepressant desipramine., Results: Our data showed that fluoxetine and desipramine exerted moderate but selective effects on glutamate receptor expression and editing, while reboxetine appeared to be the drug that affects glutamate receptors (GluR) most. The most consistent effect, observed with pronoradrenergic drugs (desipramine and reboxetine), was a decrease of GluR3 expression both in P/FC and HI. Interestingly, in HI, the same drugs also decreased the editing levels of either the flip (desipramine) or flop (reboxetine) form of GluR3., Conclusions: Overall, these results point to specific and regionally discrete changes in the expression and editing level of glutamate receptors and, in particular, to a selective reduction of conductance for GluR3-containing receptors following treatment with antidepressant drugs. These data support the hypothesis that changes in glutamate neurotransmission are involved in the therapeutic effects induced by these drugs.

Antipsychotics are the drugs of choice for the treatment of schizophrenia. Besides blocking monoamine receptors, these molecules affect intracellular signaling mechanisms, resulting in long-term synaptic alterations. Western blot analysis was used to investigate the effect of long-term administration (14 days) with the typical antipsychotic haloperidol and the atypical olanzapine on the expression and phosphorylation state of extracellular signal-related kinases (ERKs) 1 and 2 (ERK1/2), proteins involved in the regulation of multiple intracellular signaling cascades. A single injection of both drugs produced an overall decrease in ERK1/2 phosphorylation in different subcellular compartments. Conversely, long-term treatment with olanzapine, but not haloperidol, increased ERK1/2 phosphorylation in the prefrontal cortex in a compartment-specific and time-dependent fashion. In fact, ERK1/2 phosphorylation was elevated in the nuclear and cytosolic fractions 2 h after the last drug administration, whereas it was enhanced only in the membrane fraction when the animals were killed 24 h after the last injection. This effect might be the result of an activation of the mitogen-activated protein kinase pathway, because the phosphorylation of extracellular signal-regulated kinase kinase 1/2 was also increased by long-term olanzapine administration. Our data demonstrate that long-term exposure to olanzapine dynamically regulates ERK1/2 phosphorylation in different subcellular compartments, revealing a novel mechanism of action for this atypical agent and pointing to temporally separated locations of signaling events mediated by these kinases after long-term olanzapine administration.

Regulation of gene expression represents a major component in antidepressant drug action. The effect of antidepressant treatments on the function of cAMP-responsive element binding protein (CREB), a transcription factor that regulates expression of several genes involved in neuroplasticity, cell survival, and cognition, has been extensively studied. Although there is general agreement that chronic antidepressants stimulate CREB function, conflicting results suggest that different effects may depend on drug type, drug dosage, and different experimental paradigms. CREB function is activated by a vast array of physiological stimuli, conveyed through a number of signaling pathways acting in concert, but thus far the effects of antidepressants on CREB have been analyzed mostly with regard to the cAMP-protein kinase A pathway. A growing body of data shows that other major pathways, such as the calcium/calmodulin-dependent kinase and the mitogen-activated kinase cascades, are involved in activity-dependent regulation of gene expression and may also be implicated in the mechanism of action of antidepressants. In this article the available evidence is reviewed with an attempt to identify the reasons for experimental discrepancies and possible directions for future research. Particularemphasis is given to the regulation of brain-derived neurotrophic factor (BDNF), a CREB-regulated gene, which has been implicated in both the pathophysiology and pharmacology of mood disorders. The array of different results obtained by various groups is analyzed with an eye on recent advancements in the regulation of BDNF transcription, in an attempt to understand better the mechanisms of drug action and dissect molecular requirements for faster and more efficient antidepressant treatment.

Administration of drugs of abuse can produce long-lasting effects on brain function, which involve modifications at neurotransmitter level as well as changes in proteins important for structural alterations of selected brain regions. The contribution of trophic factors in these events has so far been underestimated. Here, we demonstrate that a single cocaine injection selectively up-regulated fibroblast growth factor 2 (FGF-2) mRNA levels in the striatum and prefrontal cortex within 2 h, an effect that vanished by 24 h. However, prolonged exposure (5 or 14 days) to cocaine treatment produced an enduring elevation of FGF-2 mRNA levels that was evident 72 h after the last injection in the prefrontal cortex and could even persist for 14 days in the striatum, raising the possibility that cocaine treatment primes the brain, resulting in longer-lasting FGF-2 up-regulation in regions that are highly innervated by dopaminergic projections. The expression of FGF-2 was also significantly increased in the midbrain following acute or 5-day injection, suggesting that modulation of FGF-2 biosynthesis in dopamine-producing cells occurs only during early stages of cocaine exposure. Our results point to important mechanistic conclusions as to how cocaine alters FGF-2 expression. Whereas cocaine-induced changes in FGF-2 gene expression following a single injection could be ascribed to increased release of transmitters (mainly dopamine), enhanced FGF-2 gene expression following repeated administration identifies the trophic factor as part of the adaptive changes set in motion by cocaine.

Exposure to stress during pregnancy influences the trajectory of brain development resulting in permanent alterations that may contribute to increased susceptibility to subsequent cognitive or neuropsychiatric disorders. In this manuscript, we examined the effects of prenatal stress on the expression of basic fibroblast growth factor (FGF-2), an important molecular regulator of development and plasticity, in adult male rats under basal conditions as well as in response to acute or chronic stress. Baseline FGF-2 mRNA levels were differentially influenced by gestational stress in a variety of brain regions, with significant decreases in prefrontal cortex and increases in entorhinal cortex and striatum. By itself, postnatal stress similarly decreased trophic factor expression in prefrontal cortex while evoking stimulation elsewhere. Gestational stress altered the pattern of FGF-2 expression in response to adult stress, completely reversing the pattern in the prefrontal cortex (stimulatory instead of inhibitory), blunting the response in the entorhinal cortex and desensitizing the response in the striatum. These effects point to a unique interference of chronic prenatal stress with both ongoing FGF-2 expression and its responses to subsequent stressors, lasting into adulthood. Given the multifaceted role of FGF-2 in synaptic development, maintenance and plasticity, these data provide detailed mechanistic evidence as to how prenatal stress elicits lifelong effects on synaptic function. The abnormal modulation of FGF-2 gene expression in specific brain regions in response to subsequent stress in adulthood may impair the normal adaptive responses of the cell to challenging situations.

Fibroblast growth factors (FGFs) comprise several peptides that, by interacting with a family of FGF receptors, participate in brain development and contribute to neuronal repair and plasticity. Recent evidence suggests that the expression of FGFs is altered in mood disorders and can be regulated by psychotropic drugs. This provides further support to the notion that neurotrophic molecules might have a role in the etiology and treatment of mental disorders.

Glutamate neurotransmission was recently implicated in the action of stress and in antidepressant mechanisms. We report that chronic (not acute) treatment with three antidepressants with different primary mechanisms (fluoxetine, reboxetine, and desipramine) markedly reduced depolarization-evoked release of glutamate, stimulated by 15 or 25 mm KCl, but not release of GABA. Endogenous glutamate and GABA release was measured in superfused synaptosomes, freshly prepared from hippocampus of drug-treated rats. Interestingly, treatment with the three drugs only barely changed the release of glutamate (and of GABA) induced by ionomycin. In synaptic membranes of chronically treated rats we found a marked reduction in the protein-protein interaction between syntaxin 1 and Thr286-phosphorylated alphaCaM kinase II (alpha-calcium/calmodulin-dependent protein kinase II) (an interaction previously proposed to promote neurotransmitter release) and a marked increase in the interaction between syntaxin 1 and Munc-18 (an interaction proposed to reduce neurotransmitter release). Furthermore, we found a selective reduction in the expression level of the three proteins forming the core SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex. These findings suggest that antidepressants work by stabilizing glutamate neurotransmission in the hippocampus and that they may represent a useful tool for the study of relationship between functional and molecular processes in nerve terminals.

Neurokinin 1 (NK-1) receptor knockout mice showed behavioral responses similar to animals chronically treated with antidepressants. The aim of this study was to analyse, in NK-1 receptor knockout, the molecular modifications of signaling pathways involved in the pathophysiology of depression and antidepressant mechanism. We found, in total cell cytosol from the prefrontal/frontal cortex, hippocampus and striatum, a marked up-regulation of Ca(2+)-independent enzymatic activity and Thr(286) autophosphorylation of Ca(2+)/calmodulin-dependent protein kinase (CaMK) II. Similar changes in CaMKII regulation were previously observed in rats chronically treated with antidepressants. In striatum, up-regulation of the activity and phosphorylation of CaMKII was also found in the homogenate and synaptosomes. No major changes were observed in the Ca(2+)-dependent kinase activity, with the exception of homogenate from the prefrontal/frontal cortex. We also analysed the expression and phosphorylation of presynaptic proteins, which modulate synaptic vesicle trafficking and exocytosis, and found a marked decrease in synapsin I total expression and basal phosphorylation of Ser(603) (the phosphorylation site for CaMKII) in the prefrontal/frontal cortex. Accordingly, the Ca(2+)/calmodulin-dependent posthoc endogenous phosphorylation of synapsin I in the same area was increased. The knockout of NK-1 receptor had no consequences on the expression or phosphorylation levels of the transcription factor cAMP-responsive element-binding protein and its regulating kinase CaMKIV. However, phosphorylation of ERK1/2-mitogen-activated protein kinases was reduced in the hippocampus and striatum, again resembling an effect previously observed in antidepressant-treated rats. These results show similarities between NK-1 knockouts and animals chronically treated with antidepressants and support the putative antidepressant activity of NK-1 receptor antagonists.

CaM kinase II, a regulator of synaptic plasticity, is implicated in pathophysiology and pharmacology of psychiatric disorders. Chronic treatment with antidepressants desipramine and reboxetine up-regulated CaM kinase II in neuronal cell bodies of hippocampus. mRNA/protein expression for alphaCaM kinase II was unchanged, whereas Thr phosphorylation was increased in pyramidal/granular cell bodies, suggesting that increased phosphorylation is responsible for kinase activation. Short-term treatment of neuronal cultures with reboxetine reduced kinase activation in a concentration-dependent manner. The short-term inhibitory effect of reboxetine suggests that kinase up-regulation during antidepressant drug treatment is an adaptive response compensating for initial functional down-regulation.

Dysregulation of calcium homeostasis is among the major cellular alterations in Alzheimer's disease (AD). We studied Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II), one of the major effectors regulating neuronal responses to changes in calcium fluxes, in cultured skin fibroblasts from subjects with sporadic AD. We found, by using PCR and Western analysis, that human fibroblasts express the delta-isoform of this kinase, and that CaM kinase II is the major Ca(2+)/calmodulin-dependent kinase in these cells. Protein expression level of the kinase was not significantly different in AD fibroblasts. However, the total activity of the kinase (stimulated by Ca(2+)/calmodulin) was significantly reduced in AD cell lines, whereas Ca(2+)-independent activity was significantly enhanced. The percent autonomy of the kinase (%Ca(2+)-independent/Ca(2+)-dependent activity) in AD cell lines was 62.8%, three-fold the corresponding percentage in control fibroblasts. The abnormal calcium-independent activity was not due to enhanced basal autophosphorylation of Thr(287). The observed abnormalities, if present in brain tissue, may be implicated either in dysfunction of neuroplasticity and cognitive functions or in dysregulation of cell cycle.

Regulation of gene expression is purported as a major component in the long-term action of antidepressants. The transcription factor cAMP-response element-binding protein (CREB) is activated by chronic antidepressant treatments, although a number of studies reported different effects on CREB, depending on drug types used and brain areas investigated. Furthermore, little is known as to what signaling cascades are responsible for CREB activation, although cAMP-protein kinase A (PKA) cascade was suggested to be a central player. We investigated how different drugs (fluoxetine (FLX), desipramine (DMI), reboxetine (RBX)) affect CREB expression and phosphorylation of Ser(133) in the hippocampus and prefrontal/frontal cortex (PFCX). Acute treatments did not induce changes in these mechanisms. Chronic FLX increased nuclear phospho-CREB (pCREB) far more markedly than pronoradrenergic drugs, particularly in PFCX. We investigated the function of the main signaling cascades that were shown to phosphorylate and regulate CREB. PKA did not seem to account for the selective increase of pCREB induced by FLX. All drug treatments markedly increased the enzymatic activity of nuclear Ca2+/calmodulin (CaM) kinase IV (CaMKIV), a major neuronal CREB kinase, in PFCX. Activation of this kinase was due to increased phosphorylation of the activatory residue Thr196, with no major changes in the expression levels of alpha- and beta-CaM kinase kinase, enzymes that phosphorylate CaMKIV. Again in PFCX, FLX selectively increased the expression level of MAP kinases Erk1/2, without affecting their phosphorylation. Our results show that FLX exerts a more marked effect on CREB phosphorylation and suggest that CaMKIV and MAP kinase cascades are involved in this effect.

Fibroblast growth factor-2 (FGF-2) and brain-derived neurotrophic factor (BDNF) are trophic factors, widely distributed in the adult brain, whose expression can be modulated by psychoactive drugs. Administration of the atypical antipsychotic quetiapine resulted in a marked elevation of FGF-2 and BDNF mRNA levels in the rat hippocampus, but only under conditions of reduced NMDA receptor activity. These effects were drug-specific, given that they were not observed with the conventional antipsychotic haloperidol; and anatomically defined, since no similar effect was observed in striatum, prefrontal or frontal cortex. These results suggest that quetiapine may promote neuroplasticity via the up-regulation of neurotrophic factors when NMDA-mediated transmission is perturbed.

Prenatal stress represents a well-established experimental protocol resembling some features of schizophrenia, including deficits in social interactions, disruption of prepulse inhibition and enhanced response to psychomotor stimulants. In order to evaluate molecular changes that could participate in long-lasting effects on brain function, we analysed the effects of prenatal stress on the expression of brain-derived neurotrophic factor (BDNF), an important molecular determinant of synaptic plasticity and cellular homeostasis, in adult male rats under basal conditions as well as in response to a chronic stress. The main finding is that BDNF expression is reduced in the prefrontal cortex and striatum of prenatally stressed rats. Furthermore, when exposed to chronic stress in adulthood, these rats display an altered regulation of BDNF expression in these brain structures, implying that adverse life events during gestation may interfere with the expression and function of this neurotrophin at adulthood in a region-specific manner. The dysregulation of corticostriatal BDNF expression might thus contribute to permanent alterations in brain functions leading to heightened susceptibility to psychiatric disorders.

Background: The combination of the antidepressant fluoxetine (FLX) and the atypical antipsychotic olanzapine (OLA) appears to be more effective for the treatment of resistant depression than single drugs. We hypothesize that such combination may determine a specific modulation of neuroplastic genes, which could contribute to therapeutic activity., Methods: We investigated the expression of the neurotrophic molecule basic fibroblast growth factor 2 (FGF-2) after acute or chronic administration of FLX and OLA, alone or in combination. Ribonuclease (RNase) protection assay and Western blot analysis were employed to determine FGF-2 expression in different brain structures and to identify the intracellular pathways possibly involved in FGF-2 modulation., Results: After single injection, we found that FGF-2 mRNA levels were selectively upregulated in the prefrontal cortex only when the two drugs were coadministered, an effect paralleled by a significant increase of phosphorylated protein kinase B (P-Akt) levels. Conversely, chronic treatment with a combination of FLX and OLA (FLX+OLA) increased FGF-2 mRNA levels in prefrontal cortex, as well as in hippocampus and striatum., Conclusions: Based on these data, we hypothesize a role of endogenously synthesized FGF-2 in the effects of FLX/OLA combination on brain function and plasticity, which could contribute to its superior efficacy for the treatment of resistant depression.

Background: Adverse life events occurring early in development may alter the correct program of brain maturation and render the organism more vulnerable to psychiatric disorders. Identification of persistent changes associated with these events is crucial for the development of novel therapeutic strategies., Methods: We used postnatal repeated maternal deprivation (MD) from postnatal day (PND) 2-14 to investigate changes in brain-derived neurotrophic factor (BDNF) levels. RNase protection assay and enzyme linked immunosorbent assay were employed to determine the anatomic profile of neurotrophin expression at different ages following MD., Results: We found that MD produces a short-term up-regulation of neurotrophin expression in hippocampus and prefrontal cortex, as measured on PND 17, whereas at adulthood, a selective reduction of BDNF expression was observed in prefrontal cortex. When adult animals were challenged with a chronic swim stress paradigm, both a reduced expression of BDNF in prefrontal cortex and a significant reduction in striatal protein levels were found only in control subjects, whereas levels in the MD group were not further decreased., Conclusions: Our data suggest that MD produces a significant reduction of BDNF expression within prefrontal cortex and striatum, which may render these structures less plastic and more vulnerable under challenging conditions.

Glycogen synthase kinase-3 (GSK-3) is a downstream component of the Wnt pathway and recent studies have reported abnormal levels of GSK-3beta in schizophrenia. In a sample of 147 schizophrenic patients and 212 healthy individuals, we analyzed two common SNPs at position -1727 A/T and -50 C/T and a (CAA)(n) repeat polymorphism localized in intron 1 of the gene. The results showed that the allele, genotype and haplotype distributions for the three polymorphisms investigated do not differ between schizophrenic patients in general and control subjects. However, in the subtype of paranoid schizophrenic patients, we found that the (CAA)(3)/(CAA)(5) heterozygotes were more often represented. Although taken from a small sample, our results support the reports that GSK-3beta appears to be involved in a subtype of schizophrenic patients, but not in schizophrenia in general. In conclusion, we would speculate that this gene may be linked to some features of psychotic disorders rather than to schizophrenia itself., (Copyright 2004 S. Karger AG, Basel)

The class of substituted benzamides includes compounds able to modulate dopaminergic neurons selectively and specifically. The first synthetic substituted benzamide was sulpiride, which has been replaced in the clinic by the more modern amisulpride. The compound is very selective for mesolimbic D2 and D3 receptors and, therefore, has a dual mechanism of action, which is associated with two different indications. At low doses (50 mg), amisulpride preferentially blocks presynaptic autoreceptors, producing an increase in dopamine release, and therefore acting as a dopaminergic compound able to resolve the dopaminergic hypoactivity that characterizes depression. At higher doses (400-1,200 mg), the drug exerts its activity on postsynaptic D3/D2 receptors located in the limbic region and prefrontal areas, producing selective dopaminergic inhibition, eliciting antipsychotic effects. In the present review, the clinical use of amisulpride in depressive syndromes is discussed, in particular in dysthymia and in schizophrenia. Based on experimental data, amisulpride is a treatment of choice for dopaminergic transmission disorders, both in depression and in schizophrenia.

We have investigated the role of dopaminergic receptors in modulation of basic fibroblast growth factor (FGF-2) expression in rat prefrontal cortex and hippocampus, two brain regions important for cognition. We found that FGF-2 expression is upregulated by quinpirole, a D2 agonist, in prefrontal cortex and to a lesser extent in hippocampus. This modulation was specific for dopamine D2 receptors because no effect was observed when the dopamine D1 and D3 agonists, SKF38393 and 7-OH-DPAT, respectively, were administered. Our findings show that activation of dopaminergic D2 receptors modulates FGF-2 expression in rat prefrontal cortex and hippocampus. Our data highlight the complex modulation of FGF-2 expression in limbic areas pointing to this trophic molecule as a putative target of drugs used against acute and chronic neurodegenerative diseases such as Parkinson's disease., (Copyright 2003 Wiley-Liss, Inc.)

Background: Abnormal levels of protein kinase A (PKA) were found in patients with bipolar disorder (BD). Since altered levels are generally accompanied by functional modifications, the purpose of this study was to investigate PKA activity in patients with BD., Methods: PKA activity was assessed in platelets from 20 drug-free bipolar patients and 19 controls., Results: The cAMP-stimulated PKA activity was significantly increased in bipolar patients compared with controls., Limitations: This study made use of platelets, which may not fully represent changes occurring in specific brain regions., Conclusion: This study adds to the growing evidence suggesting that abnormalities of PKA are associated with BD.

The neurotransmitter noradrenaline is known to be involved in a range of physiological and psychological processes, and dysfunctions of this neurotransmitter system have been implicated in a range of psychiatric disorders. However, the clinical utility of targeting the noradrenergic system in the treatment of such disorders has been somewhat overshadowed by the availability of agents selective for the serotonin system. A number of antidepressants with increased, but varying, selectivity for the noradrenergic system have become available in recent years, including mirtazapine, bupropion and, most recently, the first truly selective noradrenaline reuptake inhibitor, reboxetine. This review brings together current thinking on the role of noradrenaline in the aetiology and therapy of mood disorders to encourage a rational, evidence-based approach to the treatment of such disorders, and to provide suggestions and guidelines for future research in the area.

Brain-derived neurotrophic factor (BDNF) promotes a variety of neuromodulatory processes during development as well as in adulthood. This neurotrophin has been associated with synaptic plasticity, suggesting that its regulation may represent one of the mechanisms through which psychotropic drugs alter brain function. Because reduced glutamatergic function represents a major feature of schizophrenia, we investigated the effects of the concomitant administration of haloperidol or olanzapine with the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 on BDNF expression. MK-801 reduces the hippocampal expression of the neurotrophin; this effect was exacerbated by haloperidol, but it was normalized by olanzapine. Our data reveal a fine tuning of BDNF biosynthesis and a differential modulation by antipsychotic drugs when NMDA-mediated transmission is reduced, suggesting that haloperidol and olanzapine can produce different effects on brain plasticity through the modulation of BDNF expression., (Copyright 2003 Wiley-Liss, Inc.)

Background: Changes in neuroplasticity have been involved in the pathogenesis of psychiatric disorders as well as in psychotropic drug action. Calcium/calmodulin-dependent protein kinase II (CaM kinase II), an enzyme with a pivotal role in synaptic plasticity and cognitive functions, has been implicated in the action of anticonvulsants, benzodiazepines, and antidepressants, but little is known as to its role in the action of different drugs employed for treatment of psychiatric disorders., Methods: We studied the function and expression of CaM kinase II following chronic treatment of rats with two antidepressants, fluvoxamine and desipramine, a typical antipsychotic drug, haloperidol, and the typical medication for manic-depressive disorder, lithium., Results: Antidepressants significantly increased the kinase activity in presynaptic vesicles of frontal/prefrontal cortex. Haloperidol induced no change, whereas lithium significantly decreased the activity. Kinase activation by antidepressants was further demonstrated by increased phosphorylation of exogenously added recombinant synaptotagmin. Immunoreactivity of vesicular kinase (alpha-isoform) was significantly increased by reuptake blockers but not by the two other drugs. Kinetic analysis showed that limiting value of enzymatic velocity (Vmax) of the kinase for substrate was also increased by reuptake blockers and decreased by lithium; however, neither messenger ribonucleic acid nor protein expression level of the kinase was increased in frontal/prefrontal cortex homogenates of antidepressant-treated rats, suggesting the involvement of local synaptic mechanisms., Conclusions: These findings show that functional regulation of presynaptic CaM kinase II is selectively affected by different psychotropic drugs, and suggest local synaptic mechanisms for pharmacological regulation of the kinase.

Although previous studies suggested that dysfunctions in the protein kinase A (PKA) and in some of its substrates are associated with several psychiatric disorders, there is no evidence regarding the possible involvement of such components in panic disorder (PD). Thus, the aim of the present study was to investigate the levels of PKA and Rap1 in platelets from patients with such disorder. Twenty-four drug free patients with PD and 24 healthy volunteers participated to the study. Employing the Western Blot analysis, immunostaining and computer-assisted imaging, the levels of the regulatory (R, type I and type II) and the catalytic (C) subunits of PKA, and those of Rap1 were assessed in platelets from the two groups. The data show that patients with PD have significantly higher levels of platelet RI and C subunits of PKA than controls, whereas the levels of RII were unchanged. No significant differences were found in the immunolabelling of Rap1 between groups. These findings may provide clues toward understanding the involvement of cAMP signalling in anxiety disorders.

Recent preclinical and clinical studies have shown that mechanisms underlying neuronal plasticity and survival are involved in both the outcome of stressful experiences and the action of antidepressants. Whereas most antidepressants predominantly affect the brain levels of monoamine neurotransmitters, it is increasingly appreciated that they also modulate neurotransmission at synapses using the neurotransmitter glutamate (the most abundant in the brain). In the hippocampus, a main area of the limbic system involved in cognitive functions as well as attention and affect, specific molecules enriched at glutamatergic synapses mediate major changes in synaptic plasticity induced by stress paradigms or antidepressant treatments. We analyze here the modifications induced by stress or antidepressants in the strength of synaptic transmission in hippocampus, and the molecular modifications induced by antidepressants in two main mediators of synaptic plasticity: the N-methyl-D-aspartate (NMDA) receptor complex for glutamate and the Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). Both stress and antidepressants induce alterations in long-term potentiation of hippocampal glutamatergic synapses, which may be partly accounted for by the influence of environmental or drug-induced stimulation of monoaminergic pathways projecting to the hippocampus. In the course of antidepressant treatments significant changes have been described in both the NMDA receptor and CaM kinase II, which may account for the physiological changes observed. A central role in these synaptic changes is exerted by brain-derived neurotrophic factor (BDNF), which modulates both synaptic plasticity and its molecular mediators, as well as inducing morphological synaptic changes. The role of these molecular effectors in synaptic plasticity is discussed in relation to the action of antidepressants and the search for new molecular targets of drug action in the therapy of mood disorders.

Pharmacological investigations have suggested the involvement of the cAMP transduction pathway in the action of antidepressant drugs and in the pathophysiology of mood disorders. We have extended these studies to determine the time-related effects of two selective serotonin reuptake inhibitors, fluvoxamine (15 mg/kg) and paroxetine (5 mg/kg), on the cAMP-binding in rat cerebral cortex, after short and long-term treatments. Photoaffinity labelling experiments with 8-N(3)-[(32)P]cAMP were carried out in cerebrocortical soluble (S1 or S2) and microtubule fractions. In our conditions, both SSRIs administered for 5 days were unable to affect the cAMP-binding in S1, S2, and in microtubule fractions. After 12 days of treatment, paroxetine and fluvoxamine significantly enhanced the cAMP-binding to the 54 kDa protein, corresponding to the type II regulatory subunit of PKA (RII), in the S1 and microtubule fractions. Any modification in respect to controls was observed in S2, the soluble fraction devoid of microtubules. After 21 days of treatment no changes were observed in the soluble S1 fraction and in microtubules, but the cAMP-binding to the RII subunit was found to be significantly higher in the S2 fraction. The high concentration of RII, demonstrated first in microtubules (12 days) and then in the cytosol (21 days), could be the result of a time-related effect of SSRIs on PKA and its translocation from microtubule compartment to the cytosol. The present findings seem to demonstrate the capacity of SSRIs to modulate the subcellular distribution of PKA and support the involvement of the cAMP pathway in the mechanism of action of these drugs.