Proteomic analysis of rat cortical neurons after fluoxetine treatment

Identification of 14-3-3 epsilon as a regulator of the neural apoptotic pathway for chronic-stress-induced depression

Major depression is a prevalent and long-lasting psychiatric illness with severe functional impairment and high suicide rate. We have previously shown that the ventrolateral orbital cortex (VLO) plays a key role in the stress responses in mice, but the underlying mechanisms remains unclear. Here, we used proteomic method to identify differentially expressed proteins in VLO of chronic unpredictable mild stress (CUMS) mice. Of 4,953 quantified proteins, 45 proteins were differentially expressed following CUMS. The integrated pathway analyses identified 14-3-3ε and TrkB signaling as differentially downregulated in association with stress-induced depressive-like behaviors. 14-3-3ε overexpression in VLO relieved the depressive-like behaviors by rescue of Bad-mediated apoptosis. Moreover, treatment with the 14-3-3ε stabilizer FC-A precluded neuronal apoptotic signaling in VLO of depressed mice. Because 14-3-3ε provides significant protection against chronic stress, boosting 14-3-3ε expression, pharmacological stabilization of 14-3-3s (e.g. with FC-A) is identified as an exciting therapeutic target for major depression.

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Novel screening of chronic mild stress-induced depression phenotypes in mice

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Proteomics identify 14-3-3ε as a key modulator of depressive behaviors in VLO

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14-3-3ε partially reversed depressive behaviors through neural apoptotic pathway

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14-3-3ε stabilizer FC-A ameliorates depression phenotypes after chronic mild stress

Cognitive Improvement by Vorinostat through Modulation of Endoplasmic Reticulum Stress in a Corticosterone-Induced Chronic Stress Model in Mice

Chronic stress is the leading cause of memory impairment today. Various stress-based models are being developed for studying cognitive impairment. Repurposing of existing drugs in a new pharmacology class is the safest and cheapest option for treatment instead of new drug discovery. Vorinostat (VOR) is the first histone deacetylase (HDAC) inhibitor approved for the treatment of cutaneous T-cell lymphoma by the U.S. FDA. VOR follows the rule of five and is reported to cross the blood-brain barrier. Therefore, we aimed to evaluate the procognitive potential of VOR (25 mg/kg) administered by intraperitoneal (ip) route in a stress-based model of chronic corticosterone (CORT) injections (20 mg/kg, subcutaneously (sc)). The study comprised six groups. Normal mice were administered vehicle (VEH) (days 1-21, sc) in the first group, VOR (days 8-21, 25 mg/kg, ip) in the second group, and fluoxetine (FLX) (days 8-21, 15 mg/kg, oral) in the third group. Mice in the remaining three groups were given 20 mg/kg (sc) CORT for 21 days, and VOR (days 8-21, 25 mg/kg, ip) or FLX (days 8-21, 15 mg/kg, oral) was additionally administered to the treatment groups. Behavioral tests such as Morris water maze test, novel object recognition test, and object in place test were performed at the end of the dosing schedule to assess cognition. After behavior tests, mice were sacrificed, and hippocampus was separated from brain tissue for reverse transcriptase polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry studies. VOR treatment attenuated endoplasmic reticulum (ER) stress in CORT mice as evident from the reduction in DNA damage-inducible transcript 3 (Ddit3) (gene encoding CHOP), caspase 12 (Casp12), and calpain-2 (Capn2) mRNA levels, and cleaved caspase 3 (CASP3) protein expression. Bax inhibitor-1 (BI-1) was significantly increased in VOR-treated CORT mice. VOR also reversed CORT induced increase in HDAC2 level in the CA3 region. The protective effects of VOR were comparable to that of FLX in CORT mice. Thus, VOR has the potential to reverse cognitive dysfunction via modulation of ER stress markers and HDAC2.

Pharmacologically diverse antidepressants facilitate TRKB receptor activation by disrupting its interaction with the endocytic adaptor complex AP-2

Several antidepressant drugs activate tropomyosin-related kinase B (TRKB) receptor, but it remains unclear whether these compounds employ a common mechanism for TRKB activation. Here, using MS, we found that a single intraperitoneal injection of fluoxetine disrupts the interaction of several proteins with TRKB in the hippocampus of mice. These proteins included members of adaptor protein complex-2 (AP-2) involved in vesicular endocytosis. The interaction of TRKB with the cargo-docking μ subunit of the AP-2 complex (AP2M) was confirmed to be disrupted by both acute and repeated fluoxetine treatments. Of note, fluoxetine disrupted the coupling between full-length TRKB and AP2M, but not the interaction between AP2M and the TRKB C-terminal region, indicating that the fluoxetine-binding site in TRKB lies outside the TRKB:AP2M interface. ELISA experiments revealed that in addition to fluoxetine, other chemically diverse antidepressants, such as imipramine, rolipram, phenelzine, ketamine, and its metabolite 2R,6R-hydroxynorketamine, also decreased the interaction between TRKB and AP2M in vitro Silencing the expression of AP2M in a TRKB-expressing mouse fibroblast cell line (MG87.TRKB) increased cell-surface expression of TRKB and facilitated its activation by brain-derived neurotrophic factor (BDNF), observed as levels of phosphorylated TRKB. Moreover, animals haploinsufficient for the Ap2m1 gene displayed increased levels of active TRKB, along with enhanced cell-surface expression of the receptor in cultured hippocampal neurons. Taken together, our results suggest that disruption of the TRKB:AP2M interaction is a common mechanism underlying TRKB activation by several chemically diverse antidepressants.

Whole-transcriptome microarray analysis reveals regulation of Rab4 by RBM5 in neurons

RNA binding motif 5 (RBM5) is a nuclear protein that modulates gene transcription and mRNA splicing in cancer cells. The brain is among the highest RBM5-expressing organ in the body but its mRNA target(s) or functions in the CNS have not been elucidated. Here we knocked down (KO) RBM5 in primary rat cortical neurons and analyzed total RNA extracts by gene microarray vs. neurons transduced with lentivirus to deliver control (non-targeting) shRNA. The mRNA levels of Sec23A (involved in ER-Golgi transport) and the small GTPase Rab4a (involved in endocytosis/protein trafficking) were increased in RBM5 KO neurons relative to controls. At the protein level, only Rab4a was significantly increased in RBM5 KO extracts. Also, elevated Rab4a levels in KO neurons were associated with decreased membrane levels of oligomeric serotonin transporters (SERT). Finally, RBM5 KO was associated with increased uptake of membrane-derived monomeric SERT.

SIGNIFICANCE

Rab4a is involved in the regulation of endocytosis and protein trafficking in cells. In the CNS it regulates diverse neurobiological functions including (but not limited to) trafficking of transmembrane proteins involved in neurotransmission (e.g. SERT), maintaining dendritic spine size, promoting axonal growth, and modulating cognition. Our findings suggest that RBM5 regulates Rab4a in rat neurons.

Fluoxetine increases plasticity and modulates the proteomic profile in the adult mouse visual cortex

The scarce functional recovery of the adult CNS following injuries or diseases is largely due to its reduced potential for plasticity, the ability to reorganize neural connections as a function of experience. Recently, some new strategies restoring high levels of plasticity in the adult brain have been identified, especially in the paradigmatic model of the visual system. A chronic treatment with the anti-depressant fluoxetine reinstates plasticity in the adult rat primary visual cortex, inducing recovery of vision in amblyopic animals. The molecular mechanisms underlying this effect remain largely unknown. Here, we explored fluoxetine effects on mouse visual cortical plasticity, and exploited a proteomic approach to identify possible candidates mediating the outcome of the antidepressant treatment on adult cortical plasticity. We showed that fluoxetine restores ocular dominance plasticity in the adult mouse visual cortex, and identified 31 differentially expressed protein spots in fluoxetine-treated animals vs. controls. MALDITOF/TOF mass spectrometry identification followed by bioinformatics analysis revealed that these proteins are involved in the control of cytoskeleton organization, endocytosis, molecular transport, intracellular signaling, redox cellular state, metabolism and protein degradation. Altogether, these results indicate a complex effect of fluoxetine on neuronal signaling mechanisms potentially involved in restoring plasticity in the adult brain.

The contribution of proteomic studies in humans, animal models, and after antidepressant treatments to investigate the molecular neurobiology of major depression

The neurobiological basis of major depressive disorder (MDD) is only partially understood. The proposed hypotheses postulate dysregulations of monoaminergic and other neurotransmitter pathways, impaired stress responses, insufficient neurogenetic and neurotrophic processes generating maladaptive neuroplasticity, inappropriate inflammatory and metabolic responses. Proteomic approaches can provide useful contributions to the investigation of the molecular neurobiology of MDD due to their open-ended nature. Studies performed in brain regions of MDD patients which had received antidepressant (AD) treatment showed that affected proteins mainly belonged to energy pathways, transport of molecules, signaling, and synaptic transmission. Studies performed in animal models offer the advantage of more controlled experimental conditions at the expense of potential loss in relevance. The design of proteomic investigations included experiments carried out in MDD models, in naive animals treated with ADs, and in animal models subjected to AD treatments. A comparison of results suggested an overlap of several modulated pathways between MDD patients and animal models. Examples include the regulation of energy metabolism, especially oxidative phosphorylation and glycolysis, signal transduction pathways, including calcium-calmodulin kinase II, synaptic proteins, and cytoskeletal proteins. Nevertheless, the paucity of studies performed in human brains requires additional studies to confirm the correspondence.

Up-regulated 14-3-3β and 14-3-3ζ proteins in prefrontal cortex of subjects with schizophrenia: effect of psychotropic treatment

14-3-3 is a family of conserved regulatory proteins that bind to a multitude of functionally diverse signalling proteins. Various genetic studies and gene expression and proteomic analyses have involved 14-3-3 proteins in schizophrenia (SZ). On the other hand, studies about the status of these proteins in major depressive disorder (MD) are still missing. Immunoreactivity values of cytosolic 14-3-3β and 14-3-3ζ proteins were evaluated by Western blot in prefrontal cortex (PFC) of subjects with schizophrenia (SZ; n=22), subjects with major depressive disorder (MD; n=21) and age-, gender- and postmortem delay-matched control subjects (n=52). The modulation of 14-3-3β and 14-3-3ζ proteins by psychotropic medication was also assessed. The analysis of both proteins in SZ subjects with respect to matched control subjects showed increased 14-3-3β (Δ=33±10%, p<0.05) and 14-3-3ζ (Δ=29±6%, p<0.05) immunoreactivity in antipsychotic-free but not in antipsychotic-treated SZ subjects. Immunoreactivity values of 14-3-3β and 14-3-3ζ were not altered in MD subjects. These results show the specific up-regulation of 14-3-3β and 14-3-3ζ proteins in PFC of SZ subjects and suggest a possible down-regulation of both proteins by antipsychotic treatment.

Profiling of Proteins Regulated by Venlafaxine during Neural Differentiation of Human Cells

OBJECTIVE

Antidepressants are known to positively influence several factors in patients with depressive disorders, resulting in increased neurogenesis and subsequent relief of depressive disorders. To study the effects of venlafaxine during neural differentiation at the cellular level, we looked at its effect on protein expression and regulation mechanisms during neural differentiation.

METHODS

After exposing NCCIT cell-derived EBs to venlafaxine during differentiation (1 day and 7 days), changes in protein expression were analyzed by 2-DE and MALDI-TOF MS analysis. Gene levels of proteins regulated by venlafaxine were analyzed by real-time RT-PCR.

RESULTS

Treatment with venlafaxine decreased expression of prolyl 4-hydroxylase (P4HB), ubiquitin-conjugating enzyme E2K (HIP2) and plastin 3 (T-plastin), and up-regulated expression of growth factor beta-3 (TGF-β3), dihydropyrimidinase-like 3 (DPYSL3), and pyruvate kinase (PKM) after differentiation for 1 and 7 days. In cells exposed to venlafaxine, the mRNA expression patterns of HIP2 and PKM, which function as negative and positive regulators of differentiation and neuronal survival, respectively, were consistent with the observed changes in protein expression.

CONCLUSION

Our findings may contribute to improve understanding of molecular mechanism of venlafaxine.

Proteomic research in psychiatry

Psychiatric disorders such as Alzheimer's disease, schizophrenia and mood disorders are severe and disabling conditions of largely unknown origin and poorly understood pathophysiology. An accurate diagnosis and treatment of these disorders is often complicated by their aetiological and clinical heterogeneity. In recent years proteomic technologies based on mass spectrometry have been increasingly used, especially in the search for diagnostic and prognostic biomarkers in neuropsychiatric disorders. Proteomics enable an automated high-throughput protein determination revealing expression levels, post-translational modifications and complex protein-interaction networks. In contrast to other methods such as molecular genetics, proteomics provide the opportunity to determine modifications at the protein level thereby possibly being more closely related to pathophysiological processes underlying the clinical phenomenology of specific psychiatric conditions. In this article we review the theoretical background of proteomics and its most commonly utilized techniques. Furthermore the current impact of proteomic research on diverse psychiatric diseases, such as Alzheimer's disease, schizophrenia, mood and anxiety disorders, drug abuse and autism, is discussed. Proteomic methods are expected to gain crucial significance in psychiatric research and neuropharmacology over the coming decade.

Proteomic analysis of rat hippocampus exposed to the antidepressant paroxetine

Antidepressant drugs can exert significant effects on the mood of a patient suffering major depression and other disorders. These drugs generally have pharmacological actions on the uptake or metabolism of the neurotransmitters serotonin, noradrenaline and, to a lesser extent, dopamine. However, there are many aspects of antidepressant action we do not understand. We have applied proteomic analysis in a rat hippocampal model in an attempt to identify relevant molecules that operate in pathways functionally relevant to antidepressant action. Rats were administered either 5 mg/kg daily of the antidepressant paroxetine or vehicle for 12 days, then hippocampal protein was recovered and resolved by 2-D gel electrophoresis. After antidepressant exposure, we observed increased expression or modification of cytochrome c oxidase, subunit Va, cyclin-dependent kinase inhibitor 2A interacting protein, dynein, axonemal, heavy polypeptide 3 and RHO GDP-dissociation inhibitor alpha. Decreased expression or modification was observed for complexin 1 (CPLX1), alpha-synuclein, parvalbumin, ribosomal protein large P2, prohibitin, nerve growth factor, beta subunit (NGFB), peroxiredoxin 6 (PRDX6), 1-acylglycerol-3-phosphate O-acyltransferase 2_predicted, cystatin B (CYTB) and lysosomal membrane glycoprotein 1. CPLX1, the most strongly regulated protein observed, mediates the fusion of cellular transport vesicles with their target membranes and has been implicated in the pathophysiology of mood disorders, as well as antidepressant action. CPLX1 and the other proteins identified may represent links into molecular processes of importance to mood dysregulation and control, and their respective genes may represent novel candidates for studies of antidepressant pharmacogenetics.

A proteomic investigation of similarities between conventional and herbal antidepressant treatments

Increasing clinical evidence for the effectiveness of herbal antidepressants has led to investigations at the molecular level. Using two-dimensional gel electrophoresis, this study investigated similarities in protein expression between clomipramine, St John's wort and a Chinese herbal formula, xiao-yao-san, often used in mood disorder treatment. HT22 cells, derived from a mouse hippocampal cell line, were treated for 24 h, and protein expression was compared with that of the untreated cells (n = 4/group). Forty-three protein spots were found to be significantly differentially expressed (P < 0.05) in more than one of the treatment groups. Twenty-nine of these were identified using mass spectrometry. The most affected proteins were those involved in the cytoskeleton and energy metabolism, and an up-regulation of vimentin by all three treatments was confirmed by Western blotting. This study provides preliminary evidence for multiple common molecular targets between conventional and alternative antidepressants, which appear to collectively affect neuronal plasticity.

Target identification for CNS diseases by transcriptional profiling

Gene expression changes in neuropsychiatric and neurodegenerative disorders, and gene responses to therapeutic drugs, provide new ways to identify central nervous system (CNS) targets for drug discovery. This review summarizes gene and pathway targets replicated in expression profiling of human postmortem brain, animal models, and cell culture studies. Analysis of isolated human neurons implicates targets for Alzheimer's disease and the cognitive decline associated with normal aging and mild cognitive impairment. In addition to tau, amyloid-beta precursor protein, and amyloid-beta peptides (Abeta), these targets include all three high-affinity neurotrophin receptors and the fibroblast growth factor (FGF) system, synapse markers, glutamate receptors (GluRs) and transporters, and dopamine (DA) receptors, particularly the D2 subtype. Gene-based candidates for Parkinson's disease (PD) include the ubiquitin-proteosome system, scavengers of reactive oxygen species, brain-derived neurotrophic factor (BDNF), its receptor, TrkB, and downstream target early growth response 1, Nurr-1, and signaling through protein kinase C and RAS pathways. Increasing variability and decreases in brain mRNA production from middle age to old age suggest that cognitive impairments during normal aging may be addressed by drugs that restore antioxidant, DNA repair, and synaptic functions including those of DA to levels of younger adults. Studies in schizophrenia identify robust decreases in genes for GABA function, including glutamic acid decarboxylase, HINT1, glutamate transport and GluRs, BDNF and TrkB, numerous 14-3-3 protein family members, and decreases in genes for CNS synaptic and metabolic functions, particularly glycolysis and ATP generation. Many of these metabolic genes are increased by insulin and muscarinic agonism, both of which are therapeutic in psychosis. Differential genomic signals are relatively sparse in bipolar disorder, but include deficiencies in the expression of 14-3-3 protein members, implicating these chaperone proteins and the neurotransmitter pathways they support as possible drug targets. Brains from persons with major depressive disorder reveal decreased expression for genes in glutamate transport and metabolism, neurotrophic signaling (eg, FGF, BDNF and VGF), and MAP kinase pathways. Increases in these pathways in the brains of animals exposed to electroconvulsive shock and antidepressant treatments identify neurotrophic and angiogenic growth factors and second messenger stimulation as therapeutic approaches for the treatment of depression.

Time-dependent biphasic modulation of human BDNF by antidepressants in neuroblastoma cells

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.

A proteomic approach for evaluating the cell response to a novel histone deacetylase inhibitor in colon cancer cells

Epigenetic inactivation of gene expression is a general phenomenon associated with malignant transformation. Recently, we have found that a novel series of histone deacetylases (HDAC) inhibitors exhibit a broad-spectrum inhibition profile characterized by a marked effect on acetylation of histone and non-histone proteins. RC307, a representative compound of this series, caused a growth-inhibitory effect in colon carcinoma cells HCT116 associated with G2 accumulation and induction of apoptosis. The present study was designed to investigate the effect of RC307 on protein expressions in the HCT116 cells following treatment with cytotoxic drug concentrations. HCT116 cells were cultured in the absence or presence of RC307 and total cell lysates, as well as nuclear proteins, were extracted. The protein samples were then subjected to two-dimensional polyacrylamide gel electrophoresis, and the 2D gel images were compared to discover the protein changes caused by RC307 treatment. A total of 48 and 46 different spots were found to be modulated by RC307 in total lysates and nuclear proteome of HCT116 cell line. The modulated proteins were identified by tandem mass spectrometry. We found that RC307 exposure modulates proteins that are involved in proliferation, cell cycle regulation, apoptosis, gene expression, as well as chromatin and cytoskeleton organization.

Ecto-nucleotidase pathway is altered by different treatments with fluoxetine and nortriptyline

Depression is one of the most disabling diseases and causes a significant burden to both individual and society. Selective serotonin reuptake inhibitors and tricyclic antidepressants, such as fluoxetine and nortriptyline, respectively, are commonly used in treatment for depression. These antidepressants were tested on cerebral cortex and hippocampal synaptosomes after acute and chronic in vivo and in vitro treatments. In chronic treatment, fluoxetine and nortriptyline decreased ATP hydrolysis (17.8% and 16.3%, respectively) in hippocampus. In cerebral cortex, nortriptyline increased ATP (32.3%), ADP (51.8%), and AMP (59.5%) hydrolysis. However, fluoxetine decreased ATP (25.5%) hydrolysis and increased ADP (80.1%) and AMP (33.3%) hydrolysis. Significant activation of ADP hydrolysis was also observed in acute treatment with nortriptyline (49.8%) in cerebral cortex. However, in hippocampus, ATP (24.7%) and ADP (46.1%) hydrolysis were inhibited. Fluoxetine did not alter enzyme activities in acute treatment for both structures. In addition, there were significant changes in NTPDase activities when fluoxetine and nortriptyline (100, 250, and 500 microM) were tested in vitro. There was no inhibitory effect of fluoxetine and nortriptyline on AMP hydrolysis in cerebral cortex and hippocampus. The findings showed that these antidepressant drugs can affect the ecto-nucleotidase pathway, suggesting that the extracellular adenosine levels could be modulated by these drugs.

The DISC locus in psychiatric illness

The DISC locus is located at the breakpoint of a balanced t(1;11) chromosomal translocation in a large and unique Scottish family. This translocation segregates in a highly statistically significant manner with a broad diagnosis of psychiatric illness, including schizophrenia, bipolar disorder and major depression, as well as with a narrow diagnosis of schizophrenia alone. Two novel genes were identified at this locus and due to the high prevalence of schizophrenia in this family, they were named Disrupted-in-Schizophrenia-1 (DISC1) and Disrupted-in-Schizophrenia-2 (DISC2). DISC1 encodes a novel multifunctional scaffold protein, whereas DISC2 is a putative noncoding RNA gene antisense to DISC1. A number of independent genetic linkage and association studies in diverse populations support the original linkage findings in the Scottish family and genetic evidence now implicates the DISC locus in susceptibility to schizophrenia, schizoaffective disorder, bipolar disorder and major depression as well as various cognitive traits. Despite this, with the exception of the t(1;11) translocation, robust evidence for a functional variant(s) is still lacking and genetic heterogeneity is likely. Of the two genes identified at this locus, DISC1 has been prioritized as the most probable candidate susceptibility gene for psychiatric illness, as its protein sequence is directly disrupted by the translocation. Much research has been undertaken in recent years to elucidate the biological functions of the DISC1 protein and to further our understanding of how it contributes to the pathogenesis of schizophrenia. These data are the main subject of this review; however, the potential involvement of DISC2 in the pathogenesis of psychiatric illness is also discussed. A detailed picture of DISC1 function is now emerging, which encompasses roles in neurodevelopment, cytoskeletal function and cAMP signalling, and several DISC1 interactors have also been defined as independent genetic susceptibility factors for psychiatric illness. DISC1 is a hub protein in a multidimensional risk pathway for major mental illness, and studies of this pathway are opening up opportunities for a better understanding of causality and possible mechanisms of intervention.

Proteomic analysis of embryonic stem cell–derived neural cells exposed to the antidepressant paroxetine

Antidepressant drugs can have significant effects on the mood of a patient suffering from major depression or other disorders. The pharmacological actions of these drugs generally affect the uptake or metabolism of the neurotransmitters serotonin, noradrenalin, and, to a lesser extent, dopamine. However, many aspects of antidepressant action are not understood. We conducted a proteomic analysis in a neuronal cell culture model in an attempt to identify molecules important to the operation of pathways functionally relevant to antidepressant action. The model involved generating cultures containing mixed neural and glial cells by controlled differentiation of mouse embryonic stem cells, followed by exposure to 1 microM paroxetine for 14 days. After antidepressant exposure, we observed increased expression or modification of sepiapterin reductase (SPR), heat shock protein 9A, RAS and EF-hand domain containing, and protein disulfide isomerase associated 3 and decreased expression or modification of creatine kinase, actin, prohibitin, a T-cell receptor alpha chain, defensin-related cryptdin 5, and the intermediate filament proteins glial fibrillary acidic protein and vimentin. SPR, the most strongly up-regulated protein observed, controls production of tetrahydrobiopterin, an essential cofactor for the synthesis of many neurotransmitters including serotonin, making it a plausible and intriguing candidate protein for involvement in mood control and antidepressant drug action. SPR and the other proteins identified may represent links to molecular processes of importance to mood dysregulation and control, and their respective genes may be novel candidates for the study of antidepressant pharmacogenetics.

Neuroproteomics and its applications in research on nicotine and other drugs of abuse

The rapidly growing field of neuroproteomics is able to track changes in protein expression and protein modifications underlying various physiological conditions, including the neural diseases related to drug addiction. Thus, it presents great promise in characterizing protein function, biochemical pathways, and networks to understand the mechanisms underlying drug dependence. In this article, we first provide an overview of proteomics technologies and bioinformatics tools available to analyze proteomics data. Then we summarize the recent applications of proteomics to profile the protein expression pattern in animal or human brain tissues after the administration of nicotine, alcohol, amphetamine, butorphanol, cocaine, and morphine. By comparing the protein expression profiles in response to chronic nicotine exposure with those appearing in response to treatment with other drugs of abuse, we identified three biological processes that appears to be regulated by multiple drugs of abuse: energy metabolism, oxidative stress response, and protein degradation and modification. Such similarity indicates that despite the obvious differences among their chemical properties and the receptors with which they interact, different substances of abuse may cause some similar changes in cellular activities and biological processes in neurons.