Regulation Of Neurotransmission Research Articles

DNA Damage in Major Psychiatric Diseases

Human cells are exposed to exogenous insults and continuous production of different metabolites. These insults and unwanted metabolic products might interfere with the stability of genomic DNA. Recently, many studies have demonstrated that different psychiatric disorders show substantially high levels of oxidative DNA damage in the brain accompanied with morphological and functional alterations. It reveals that damaged genomic DNA may contribute to the pathophysiology of these mental illnesses. In this article, we review the roles of oxidative damage and reduced antioxidant ability in some vastly studied psychiatric disorders and emphasize the inclusion of treatment options involving DNA repair. In addition, while most currently used antidepressants are based on the manipulation of the neurotransmitter regulation in managing different mental abnormalities, they are able to prevent or reverse neurotoxin-induced DNA damage. Therefore, it may be plausible to target on genomic DNA alterations for psychiatric therapies, which is of pivotal importance for future antipsychiatric drug development.

Antidepressant-like effects of water extract of Gastrodia elata Blume in rats exposed to unpredictable chronic mild stress via modulation of monoamine regulatory pathways

Ethnopharmacology relevanceGastrodia elata Blume (GE) is a traditional herbal medicine belonging to the Orchidaceae family, and has been used to manage neurological disorders for centuries. We have previously reported that its water extract (WGE) could improve the depressive-like behaviours in the forced swimming test (FST), an animal model of depression. Aim of the studyTo investigate the antidepressant-like effects of WGE in rats exposed to unpredictable chronic mild stress (UCMS) model, and to explore its possible molecular mechanisms. Materials and methodsUCMS rats were orally administered with WGE (0.5g/kg body weight) daily within the 4 weeks UCMS procedure. The sucrose preference test and the open field test were conducted to assess anhedonia and spontaneous behaviours, respectively. The cerebral turnover rates of monoamine neurotransmitters and the serum corticosterone levels were measured. In vitro direct and indirect monoamine oxidase A (MAO-A) inhibitory assays were employed to assess the possible antidepressant-like mechanisms of WGE (0.5mg/mL) and its major component, gastrodin (GAS, 15, 30 and 60μg/mL). Western blot was used to examine the expression of protein related to monoamine regulation, such as MAO-A and tyrosine hydroxylase (TH). ResultsWGE significantly reversed the sucrose preference and other abnormal behaviours induced by 4 weeks of UCMS. WGE significantly restored the cerebral turnover rates of serotonin and dopamine and decreased serum corticosterone levels. WGE and gastrodin inhibited the activity and protein expression of MAO-A, and increased TH levels in PC12 cells. ConclusionThe antidepressant-like effects of WGE and gastrodin might be mediated by the regulation of monoamine neurotransmitters, and therefore were beneficial in depression treatment as a complementary approach.

The local expression and trafficking of tyrosine hydroxylase mRNA in the axons of sympathetic neurons.

Synthesis and regulation of catecholamine neurotransmitters in the central nervous system are implicated in the pathogenesis of a number of neuropsychiatric disorders. To identify factors that regulate the presynaptic synthesis of catecholamines, we tested the hypothesis that the rate-limiting enzyme of the catecholamine biosynthetic pathway, tyrosine hydroxylase (TH), is locally synthesized in axons and presynaptic nerve terminals of noradrenergic neurons. To isolate pure axonal mRNA and protein, rat superior cervical ganglion sympathetic neurons were cultured in compartmentalized Campenot chambers. qRT-PCR and RNA in situ hybridization analyses showed that TH mRNA is present in distal axons. Colocalization experiments with nerve terminal marker proteins suggested that both TH mRNA and protein localize in regions of the axon that resemble nerve terminals (i.e., synaptic boutons). Analysis of polysome-bound RNA showed that TH mRNA is present in polysomes isolated from distal axons. Metabolic labeling of axonally synthesized proteins labeled with the methionine analog, L-azidohomoalanine, showed that TH is locally synthesized in axons. Moreover, the local transfection and translation of exogenous TH mRNA into distal axons facilitated axonal dopamine synthesis. Finally, using chimeric td-Tomato-tagged constructs, we identified a sequence element within the TH 3′UTR that is required for the axonal localization of the reporter mRNA. Taken together, our results provide the first direct evidence that TH mRNA is trafficked to the axon and that the mRNA is locally translated. These findings raise the interesting possibility that the biosynthesis of the catecholamine neurotransmitters is locally regulated in the axon and/or presynaptic nerve terminal.

Iron function and dysfunction in the brain: A pediatric neurologist's perspective

Iron plays a critical role in brain development and physiology, cytoplasmic protein function, and mitochondrial reactions. Brain iron levels are regulated tightly, and pathologies can result from both iron deficiency (learning and memory deficits, neuronal and dendritic developmental alterations, impaired myelin function, and abnormal neurotransmitter regulation) and iron overload (free radical production and oxidative stress, as proposed for Parkinson and Alzheimer diseases as well as rare genetic disorders of iron accumulation). This review briefly summarizes the roles of iron in normal and abnormal brain function, with emphasis on the developing brain, and describes some disorders deriving from deficient or excessive iron levels.

A polymorphism in the norepinephrine transporter gene is associated with affective and cardiovascular disease through a microRNA mechanism.

Norepinephrine released from sympathetic nerves is removed from the neuroeffector junction via the action of the norepinephrine transporter (NET). NET impairment is evident in several clinically important conditions including major depressive disorder (MDD), panic disorder (PD), essential hypertension and the postural orthostatic tachycardia syndrome (POTS). We aimed to determine whether a single nucleotide polymorphism (SNP) in the 3' untranslated region (UTR) of the NET gene is associated with NET impairment and to elucidate the mechanisms involved. The analyses were carried out in two cohorts of European ancestry, which included healthy controls and MDD, PD, hypertensive and POTS patients. Compared with controls, cases had significantly higher prevalence of the T allele of rs7194256 (C/T), arterial norepinephrine, depression and anxiety scores, larger left ventricular mass index, higher systolic and diastolic blood pressures, and heart rate. Bioinformatic analysis identified that the microRNA miR-19a-3p could bind preferentially to the sequence created by the presence of the T allele. This was supported by results of luciferase assays. Compared with controls, cases had significantly lower circulating miR-19a-3p, which was associated with pathways related to blood pressure and regulation of neurotransmission. In vitro norepinephrine downregulated miR-19a-3p. In conclusion, the T allele of the rs7194256 SNP in the 3'UTR of the NET gene is more prevalent in diseases where NET impairment is evident. This might be explained by the creation of a binding site for the microRNA miR-19a-3p. A defect in NET function may potentiate the sympathetic neurochemical signal, predisposing individuals with affective diseases to increased risk of cardiovascular disease development.

The contribution of alpha synuclein to neuronal survival and function - Implications for Parkinson's disease.

The aggregation of alpha synuclein (α‐syn) is a neuropathological feature that defines a spectrum of disorders collectively termed synucleinopathies, and of these, Parkinson's disease (PD) is arguably the best characterized. Aggregated α‐syn is the primary component of Lewy bodies, the defining pathological feature of PD, while mutations or multiplications in the α‐syn gene result in familial PD. The high correlation between α‐syn burden and PD has led to the hypothesis that α‐syn aggregation produces toxicity through a gain‐of‐function mechanism. However, α‐syn has been implicated to function in a diverse range of essential cellular processes such as the regulation of neurotransmission and response to cellular stress. As such, an alternative hypothesis with equal explanatory power is that the aggregation of α‐syn results in toxicity because of a toxic loss of necessary α‐syn function, following sequestration of functional forms α‐syn into insoluble protein aggregates. Within this review, we will provide an overview of the literature linking α‐syn to PD and the knowledge gained from current α‐syn‐based animal models of PD. We will then interpret these data from the viewpoint of the α‐syn loss‐of‐function hypothesis and provide a potential mechanistic model by which loss of α‐syn function could result in at least some of the neurodegeneration observed in PD. By providing an alternative perspective on the etiopathogenesis of PD and synucleinopathies, this may reveal alternative avenues of research in order to identify potential novel therapeutic targets for disease modifying strategies. The correlation between α‐synuclein burden and Parkinson's disease pathology has led to the hypothesis that α‐synuclein aggregation produces toxicity through a gain‐of‐function mechanism. However, in this review, we discuss data supporting the alternative hypothesis that the aggregation of α‐synuclein results in toxicity because of loss of necessary α‐synuclein function at the presynaptic terminal, following sequestration of functional forms of α‐synuclein into aggregates.

Role of interleukin-10 (IL-10) in regulation of GABAergic transmission and acute response to ethanol

Mounting evidence indicates that ethanol (EtOH) exposure activates neuroimmune signaling. Alterations in pro-inflammatory cytokines after acute and chronic EtOH exposure have been heavily investigated. In contrast, little is known about the regulation of neurotransmission and/or modulation by anti-inflammatory cytokines in the brain after an acute EtOH exposure. Recent evidence suggests that interleukin-10 (IL-10), an anti-inflammatory cytokine, is upregulated during withdrawal from chronic EtOH exposure. In the present study, we show that IL-10 is increased early (1 h) after a single intoxicating dose of EtOH (5 g/kg, intragastric) in Sprague Dawley rats. We also show that IL-10 rapidly regulates GABAergic transmission in dentate gyrus neurons. In brain slice recordings, IL-10 application dose-dependently decreases miniature inhibitory postsynaptic current (mIPSC) area and frequency, and decreases the magnitude of the picrotoxin sensitive tonic current (Itonic), indicating both pre- and postsynaptic mechanisms. A PI3K inhibitor LY294002 (but not the negative control LY303511) ablated the inhibitory effects of IL-10 on mIPSC area and Itonic, but not on mIPSC frequency, indicating the involvement of PI3K in postsynaptic effects of IL-10 on GABAergic transmission. Lastly, we also identify a novel neurobehavioral regulation of EtOH sensitivity by IL-10, whereby IL-10 attenuates acute EtOH-induced hypnosis. These results suggest that EtOH causes an early release of IL-10 in the brain, which may contribute to neuronal hyperexcitability as well as disturbed sleep seen after binge exposure to EtOH. These results also identify IL-10 signaling as a potential therapeutic target in alcohol-use disorders and other CNS disorders where GABAergic transmission is altered.

The role of neurotransmitters in regulation of energy homeostasis and possibility of drug correction of its disturbances in obesity

In today's world the problem of obesity is discussed in the context of non-communicable diseases, leading to significant encumbrances on society. This article provides information about the basics of the regulation of energy balance and eating behavior. Particular attention is paid to the role of neurotransmitters, including serotonin, a metabolic disorder that is one of the suspected causes of eating disorders. Demonstrated experience in the use of sibutramine in the world, and in the Russian practice, taking into account the impact on the development of comorbid conditions and their complications.

Gene Expression Profiling of Evening Fatigue in Women Undergoing Chemotherapy for Breast Cancer

Moderate-to-severe fatigue occurs in up to 94% of oncology patients undergoing active treatment. Current interventions for fatigue are not efficacious. A major impediment to the development of effective treatments is a lack of understanding of the fundamental mechanisms underlying fatigue. In the current study, differences in phenotypic characteristics and gene expression profiles were evaluated in a sample of breast cancer patients undergoing chemotherapy (CTX) who reported low (n = 19) and high (n = 25) levels of evening fatigue. Compared to the low group, patients in the high evening fatigue group reported lower functional status scores, higher comorbidity scores, and fewer prior cancer treatments. One gene was identified as upregulated and 11 as downregulated in the high evening fatigue group. Gene set analysis found 24 downregulated and 94 simultaneously up- and downregulated pathways between the two fatigue groups. Transcript origin analysis found that differential expression (DE) originated primarily from monocytes and dendritic cell types. Query of public data sources found 18 gene expression experiments with similar DE profiles. Our analyses revealed that inflammation, neurotransmitter regulation, and energy metabolism are likely mechanisms associated with evening fatigue severity; that CTX may contribute to fatigue seen in oncology patients; and that the patterns of gene expression may be shared with other models of fatigue (e.g., physical exercise and pathogen-induced sickness behavior). These results suggest that the mechanisms that underlie fatigue in oncology patients are multifactorial.

Novel Therapeutic Strategies for Dementia.

Dementia represents a major problem of health and disability, with a relevant economic impact on our society. Despite important advances in pathogenesis, diagnosis and treatment, its primary causes still remain elusive, accurate biomarkers are not well characterized, and the available pharmacological treatments are not cost-effective. Alzheimer disease (AD), the most prevalent form of dementia, is a polygenic/multifactorial/complex disorder in which hundreds of defective genes distributed across the human genome may contribute to its pathogenesis. Diverse environmental factors, cerebrovascular dysfunction, and epigenetic phenomena, together with structural and functional genomic dysfunctions lead to amyloid deposition, neurofibrillary tangle formation and premature neuronal death, the major neuropathological hallmarks of AD. For the past 20 years, over 1,000 different compounds have been studied as potential candidate drugs for the treatment of AD. About 50% of these substances are novel molecules obtained from natural sources. The candidate compounds can be classified according to their pharmacological properties and/or the AD-related pathogenic cascade to which they are addressed to halt disease progression. In addition to the Food and Drug Administration (FDA)-approved drugs since 1993 (tacrine, donepezil, rivastigmine, galantamine, memantine), most candidate strategies fall into 6 major categories: (i) novel cholinesterase inhibitors and neurotransmitter regulators, (ii) anti-amyloid beta (Aβ) treatments (amyloid-β protein precursor (APP) regulators, Aβ breakers, active and passive immunotherapy with vaccines and antibodies, β - and γ - secretase inhibitors or modulators), (iii) anti-tau treatments, (iv) pleiotropic products (most of them of natural origin), (v) epigenetic intervention, and (vi) combination therapies. The implementation of pharmacogenomic strategies will contribute to optimize drug development and therapeutics in AD and related disorders.

Shawn, theDrosophilaHomolog of SLC25A39/40, Is a Mitochondrial Carrier That Promotes Neuronal Survival

Mitochondria play an important role in the regulation of neurotransmission, and mitochondrial impairment is a key event in neurodegeneration. Cells rely on mitochondrial carrier proteins of the SLC25 family to shuttle ions, cofactors, and metabolites necessary for enzymatic reactions. Mutations in these carriers often result in rare but severe pathologies in the brain, and some of the genes, including SLC25A39 and SLC25A40, reside in susceptibility loci of severe forms of epilepsy. However, the role of most of these carriers has not been investigated in neurons in vivo. We identified shawn, the Drosophila homolog of SLC25A39 and SLC25A40, in a genetic screen to identify genes involved in neuronal function. Shawn localizes to mitochondria, and missense mutations result in an accumulation of reactive oxygen species, mitochondrial dysfunction, and neurodegeneration. Shawn regulates metal homeostasis, and we found in shawn mutants increased levels of manganese, calcium, and mitochondrial free iron. Mitochondrial mutants often cannot maintain synaptic transmission under demanding conditions, but shawn mutants do, and they also do not display endocytic defects. In contrast, shawn mutants harbor a significant increase in neurotransmitter release. Our work provides the first functional annotation of these essential mitochondrial carriers in the nervous system, and the results suggest that metal imbalances and mitochondrial dysfunction may contribute to defects in synaptic transmission and neuronal survival. We describe for the first time the role of the mitochondrial carrier Shawn/SLC25A39/SLC25A40 in the nervous system. In humans, these genes reside in susceptibility loci for epilepsy, and, in flies, we observe neuronal defects related to mitochondrial dysfunction and metal homeostasis defects. Interestingly, shawn mutants also harbor increased neurotransmitter release and neurodegeneration. Our data suggest a connection between maintaining a correct metal balance and mitochondrial function to regulate neuronal survival and neurotransmitter release.

Identification of drugs that restore primary cilium expression in cancer cells.

The development of cancer is often accompanied by a loss of the primary cilium, a microtubule-based cellular protrusion that functions as a cellular antenna and that puts a break on cell proliferation. Hence, restoration of the primary cilium in cancer cells may represent a novel promising approach to attenuate tumor growth. Using a high content analysis-based approach we screened a library of clinically evaluated compounds and marketed drugs for their ability to restore primary cilium expression in pancreatic ductal cancer cells. A diverse set of 118 compounds stimulating cilium expression was identified. These included glucocorticoids, fibrates and other nuclear receptor modulators, neurotransmitter regulators, ion channel modulators, tyrosine kinase inhibitors, DNA gyrase/topoisomerase inhibitors, antibacterial compounds, protein inhibitors, microtubule modulators, and COX inhibitors. Certain compounds also dramatically affected the length of the cilium. For a selection of compounds (Clofibrate, Gefitinib, Sirolimus, Imexon and Dexamethasone) their ability to restore ciliogenesis was confirmed in a panel of human cancer cell line models representing different cancer types (pancreas, lung, kidney, breast). Most compounds attenuated cell proliferation, at least in part through induction of the primary cilium, as demonstrated by cilium removal using chloral hydrate. These findings reveal that several commonly used drugs restore ciliogenesis in cancer cells, and warrant further investigation of their antineoplastic properties.

The role of urinary nerve growth factor for the diagnosis and assessment of the biofeedback success in children with dysfunctional voiding

Dysfunctional voiding (DV) occurs in neurologically normal children who are not able to establish brain control on detrusor muscle contractions (DMCs). It is also reported to be the result of incorrect voiding habits during toilet training. Children contract pelvic floor muscles (PFMs) to suppress DMC and DV begins. Urinary nerve growth factor (uNGF) is necessary for the synthesis and regulation of neurotransmitters, development of dorsal root ganglia (sensory neurons), and development of sympathetic cells during embryonic and post-natal life. uNGF has also a role in the intracellular signal transduction in nerve cells towards the target organ. To our knowledge, no study has investigated the association between uNGF, biofeedback treatment and DV in children. The aim was to examine the potential effect of uNGF in the assessment of the effectiveness of biofeedback success in children with lower urinary tract disorders. Fifty-two children with the suspicion of DV and 48 children from a primary school reporting no urinary complaints were enrolled in this study from October 2010 to April 2013 in the Urology Department. uNGF levels were compared. The mean uNGF/creatinine (Cr) level was 0.23 ± 0.26 in the control group and 0.96 ± 0.88 in the DV group (p < 0.001). The mean uNGF/Cr levels in the DV group at baseline and at the end of biofeedback therapy at 6 and 12 months were 0.90 ± 0.78, 0.26 ± 0.32, and 0.40 ± 0.50, respectively (p < 0.001) (Figure). To our knowledge this study is the first to show the correlations between uNGF levels and biofeedback therapy in children with DV. Tissue NGF in 12 patients with overactive bladder (OAB)/detrusor overactivity and 15 healthy women was previously compared and it was suggested that there was no correlation between bladder tissue NGF and OAB. uNGF levels in the bladder in patients with interstitial cystitis and idiopathic sensorial urgency were evaluated previously, and uNGF levels reported. Similar to these reports, most of the previous studies handled uNGF in patients with diseases such as interstitial cystitis, OAB, urinary tract infections, urolithiasis, spinal cord injury, and prostate cancer, and found significantly higher uNGF levels. These studies were generally in adults. A previous study about uNGF comprised 40 children with OAB, in contrast to other studies. According to this study, 40 children diagnosed with OAB were administered anti-muscarinic therapy (oxybutynin 0.3-0.5 mg/kg/day). It was reported that uNGF/Cr levels of the OAB group were higher than control group. In the current study, we evaluated the uNGF difference in DV and the effect of biofeedback treatment on uNGF levels. uNGF levels were higher in children with DV and decreased after biofeedback therapy. uNGF levels could be used for the diagnosis and the assessment of biofeedback success in these children.

Astrocyte sodium signaling and the regulation of neurotransmission.

The transmembrane Na(+) concentration gradient is an important source of energy required not only to enable the generation of action potentials in excitable cells, but also for various transmembrane transporters both in excitable and non-excitable cells, like astrocytes. One of the vital functions of astrocytes in the central nervous system (CNS) is to regulate neurotransmitter concentrations in the extracellular space. Most neurotransmitters in the CNS are removed from the extracellular space by Na(+) -dependent neurotransmitter transporters (NeuTs) expressed both in neurons and astrocytes. Neuronal NeuTs control mainly phasic synaptic transmission, i.e., synaptically induced transient postsynaptic potentials, while astrocytic NeuTs contribute to the termination of phasic neurotransmission and modulate the tonic tone, i.e., the long-lasting activation of extrasynaptic receptors by neurotransmitter that has diffused out of the synaptic cleft. Consequently, local intracellular Na(+) ([Na(+) ]i ) transients occurring in astrocytes, for example via the activation of ionotropic neurotransmitter receptors, can affect the driving force for neurotransmitter uptake, in turn modulating the spatio-temporal profiles of neurotransmitter levels in the extracellular space. As some NeuTs are close to thermodynamic equilibrium under resting conditions, an increase in astrocytic [Na(+) ]i can stimulate the direct release of neurotransmitter via NeuT reversal. In this review we discuss the role of astrocytic [Na(+) ]i changes in the regulation of uptake/release of neurotransmitters. It is emphasized that an activation of one neurotransmitter system, including either its ionotropic receptor or Na(+) -coupled co-transporter, can strongly influence, or even reverse, other Na(+) -dependent NeuTs, with potentially significant consequences for neuronal communication. GLIA 2016;64:1655-1666.

MPTH-25AN 18-GENE EXPRESSION SIGNATURE PREDICTS RECURRENCE-FREE SURVIVAL IN MENINGIOMA

Meningioma is the most common primary brain tumor and carries a substantial risk of local recurrence. While WHO grade correlates with recurrence to a degree, there is substantial within-grade variation of recurrence risk and current risk stratification does not accurately predict which patients are likely to benefit from adjuvant radiation therapy. We hypothesized that recurrent tumors have unique gene expression profiles (GEP) that could be used to better stratify patients for radiation therapy. We optimized a recurrence predictor using a training/validation approach and a support vector machine classification method with radial-basis smoothing kernel. Three publicly available Affymetrix gene expression datasets ({type:entrez-geo,attrs:{text:GSE9438,term_id:9438}}GSE9438, {type:entrez-geo,attrs:{text:GSE16581,term_id:16581}}GSE16581, {type:entrez-geo,attrs:{text:GSE43290,term_id:43290}}GSE43290) combining 127 newly diagnosed meningioma samples served as the training set. Unsupervised variable selection was used to identify an 18-gene GEP model (18-GEP) that separated recurrences with a negligible root mean square error of 0.17. The characteristics of the training dataset were as follows: WHO grade [I-92(73%), II-32(25%), III-2(2%)]; median follow-up = 5.53 years (range:0.05-25.42); recurrences = 18. This model was tested on 62 cases from our institution [validation dataset (VD)] with similar demographics, but enriched for cases with either long clinical follow-up or known recurrence. When applied to the VD, the 18-GEP separated recurrences with a misclassification error rate of 0.25 (log-rank p = 0.0003). 18-GEP was significantly predictive of tumor recurrence, independently [p = 0.0007, HR = 7.91, 95%CI = 2.35-35.78)] and was predictive after adjustment for WHO grade, mitotic index, and Simpson grade [p = 0.047, HR = 4.73, 95%CI = (1.02-26.55)]. The expression signature included genes encoding proteins involved in normal embryonic development, cell proliferation, tumor growth and invasion (FGF9, SEMA3C, EDNRA), angiogenesis (angiopoietin-2), cell cycle regulation (CDKN1A), membrane signaling (tetraspanin-7, caveolin-2), WNT-pathway inhibitors (DKK3), complement system (C1QA) and neurotransmitter regulation (SLC1A3, Secretogranin-II). In conclusion, our gene expression classifier accurately stratifies patients with meningioma by recurrence risk and has the potential to guide therapy.

Cross-talk between α7 nAchR and NMDAR revealed by protein profiling

Functional regulation of NMDA receptor (NMDAR) by the activation of α7 nicotinic acetylcholine receptor (α7nAChR) has been reported, although the molecular signaling pathway underlying this process remains largely unknown. We employed a label-free quantitative proteomics approach to identify potential intracellular molecules and pathways that might be involved in the functional cross-talk between NMDAR and α7nAChR. 43 proteins showed significantly expression changes after choline treatment in which 35 out of 43 proteins was significantly altered by co-treatment with NMDA. Western blot analysis verified proteins expression determined by LC-MS. Furthermore, protein expression in vivo in neurons from fetal rats were visualized and quantified by Confocal microscopy, which showed consistency of relative changes of AHA-1 expression measured by LC-MS and Western blot. Biological network analysis of differently expressed proteins found 21 kind of biological pathways involved. Of those pathways, 6 pathways were directly involved in regulation of neurotransmitters. Lastly, the levels of neurotransmitters (dopamine, glutamate, GABA and 5-HT) were measured by HPLC-ECD. Co-treatment choline/NMDA significantly enhances the release of dopamine, glutamate and GABA and dramatically decrease 5-HT to only 65% of control level, which is consist with this protein interaction network analysis, providing an additional evidence for the cross-talk between NMDAR and α7nAChR.

Intranasal Insulin and Insulin-Like Growth Factor 1 as Neuroprotectants in Acute Ischemic Stroke.

Treatment options for stroke remain limited. Neuroprotective therapies, in particular, have invariably failed to yield the expected benefit in stroke patients, despite robust theoretical and mechanistic background and promising animal data. Insulin and insulin-like growth factor 1 (IGF-1) play a pivotal role in critical brain functions, such as energy homeostasis, neuronal growth, and differentiation. They may exhibit neuroprotective properties in acute ischemic stroke based upon their vasodilatory, anti-inflammatory and antithrombotic effects, as well as improvements of functional connectivity, neuronal metabolism, neurotransmitter regulation, and remyelination. Intranasally administered insulin has demonstrated a benefit for prevention of cognitive decline in older people, and IGF-1 has shown potential benefit to improve functional outcomes in animal models of acute ischemic stroke. The intranasal route presents a feasible, tolerable, safe, and particularly effective administration route, bypassing the blood-brain barrier and maximizing distribution to the central nervous system (CNS), without the disadvantages of systemic side effects and first-pass metabolism. This review summarizes the neuroprotective potential of intranasally administered insulin and IGF-1 in stroke patients. We present the theoretical background and pathophysiologic mechanisms, animal and human studies of intranasal insulin and IGF-1, and the safety and feasibility of intranasal route for medication administration to the CNS.

The mechanisms of action of St. John's wort: an update.

Pharmacological research confirms and supports the clinically observed antidepressant efficacy of St. John's wort (Hypericum perforatum L., SJW). This contribution is an update of a former review by the authors in 2007. Positive evidence of antidepressant effects has been found with SJW preparations, extract fractions, and single constituents. The efficacy of SJW is obviously defined by a range of parallel mechanisms of action, triggered by different constituents. In vitro research showed, among other tests, positive effects in neurotransmitter regulation (in beta adrenergic systems and glutamate receptors) and ion channel conductance. Antidepressant effects were confirmed in typical in vivo models such as the forced swimming test, the open field test, the tail suspension test, or a model of stress-impaired memory. The overall effect cannot be attributed to a single constituent or fraction. SJW is therefore an outstanding example of the total extract being defined as the active constituent of herbal medicines.

Insulin neuroprotection and the mechanisms.

Objective:To analyze the mechanism of neuroprotection of insulin and which blood glucose range was benefit for insulin exerting neuroprotective action.Data Sources:The study is based on the data from PubMed.Study Selection:Articles were selected with the search terms “insulin”, “blood glucose”, “neuroprotection”, “brain”, “glycogen”, “cerebral ischemia”, “neuronal necrosis”, “glutamate”, “γ-aminobutyric acid”.Results:Insulin has neuroprotection. The mechanisms include the regulation of neurotransmitter, promoting glycogen synthesis, and inhibition of neuronal necrosis and apoptosis. Insulin could play its role in neuroprotection by avoiding hypoglycemia and hyperglycemia.Conclusions:Intermittent and long-term infusion insulin may be a benefit for patients with ischemic brain damage at blood glucose 6–9 mmol/L.

Neuropharmacology of purinergic receptors in human submucous plexus: Involvement of P2X1, P2X2, P2X3 channels, P2Y and A3 metabotropic receptors in neurotransmission

RationaleThe role of purinergic signaling in human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. Experimental approachLSCM-Fluo-4/(Ca2+)-imaging of postsynaptic Ca2+ transients (PSCaTs) was used as a reporter of synaptic transmission evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons (identified by HuC/D-immunoreactivity) in 235 ganglia from 107 patients; P2XR-immunoreactivity was evaluated in 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging tested effects of adenosine on fast excitatory synaptic potentials (fEPSPs). ResultsSynaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines: Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50 = 25 µM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50 = 111 nM) in neurons without stimulatory ADPbS responses (EC50 = 960 nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca2+ transients or Ca2+ oscillations (ATP,EC50 = 400 mM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20 nM) or high (5 µM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-immunoreactivity follow the order P2X2 > P2X1 >> P2X3; P2X1 + P2X2 and P2X3 + P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1–7, P2Y1,2,12–14R. ConclusionsPurines are critical regulators of neurotransmission in human ENS. Purinergic signaling involves P2X1, P2X2, P2X3 channels, P2X1 + P2X2 co-localization and inhibitory P2Y or A3 receptors. These are potential novel therapeutic targets for neurogastroenterology.