Type-B monoamine oxidase inhibitors in neurological diseases:clinical applications based on preclinical findings

Type-B monoamine oxidase inhibitors,encompassing selegiline,rasagiline,and safinamide,are available to treat Parkinson's disease.These drugs ameliorate motor symptoms and improve motor fluctuation in the advanced stages of the disease.There is also evidence suppo rting the benefit of type-B monoamine oxidase inhibitors on non-motor symptoms of Parkinson's disease,such as mood deflection,cognitive impairment,sleep disturbances,and fatigue.Preclinical studies indicate that type-B monoamine oxidase inhibitors hold a strong neuroprotective potential in Parkinson's disease and other neurodegenerative diseases for reducing oxidative stress and stimulating the production and release of neurotrophic factors,particularly glial cell line-derived neurotrophic factor,which suppo rt dopaminergic neurons.Besides,safinamide may interfere with neurodegenerative mechanisms,countera cting excessive glutamate overdrive in basal ganglia motor circuit and reducing death from excitotoxicity.Due to the dual mechanism of action,the new generation of type-B monoamine oxidase inhibitors,including safinamide,is gaining interest in other neurological pathologies,and many supporting preclinical studies are now available.The potential fields of application concern epilepsy,Duchenne muscular dystrophy,multiple scle rosis,and above all,ischemic brain injury.The purpose of this review is to investigate the preclinical and clinical pharmacology of selegiline,rasagiline,and safinamide in Parkinson's disease and beyond,focusing on possible future therapeutic applications.

Monoamine Oxidase-B Inhibitor Rasagiline Effects on Motor and Non-Motor Symptoms in Individuals with Parkinson’s Disease: A Systematic Review and Meta-Analysis

Objective: In the manuscript titled Monoamine Oxidase-B Inhibitor Rasagiline Effects on Motor and Non-Motor Symptoms in Individuals with Parkinsons Disease: A Systematic Review and Meta-Analysis, the objective was to conduct a systematic review with meta-analysis to investigate the effects that Rasagiline has on motor and non-motor symptoms in individuals with PD. Introduction: Rasagiline is a second-generation monoamine oxidase-B (MAO-B) inhibitor used both as monotherapy and adjunctive therapy for Parkinsons Disease (PD). Methods: A systematic literature search and meta-analysis were performed with randomized control trials that investigated the effects of Rasagiline on motor and non-motor symptoms in individuals with PD. The systematic search was conducted in PubMed, Cochrane, and EBSCO databases. Methodological quality was assessed using the Cochrane Grading Recommendations Assessment, Development and Evaluation approach. Results: Fourteen studies were included in our review. There were trivial to small and statistically significant improvements in motor symptoms for individuals with PD treated with Rasagiline compared to placebo. Non-motor symptoms showed no significant improvement with Rasagiline compared to placebo in five of six meta-analyses. Results were based on very low to moderate certainty of evidence. Conclusion: 1 mg/day Rasagiline significantly improved Parkinsonian motor symptoms in individuals with PD compared with placebo. For all outcomes, the 1 mg/day Rasagiline group was favored over the placebo group.

Effects of Yulangsan polysaccharide on monoamine neurotransmitters, adenylate cyclase activity and brain-derived neurotrophic factor expression in a mouse model of depression induced by unpredictable chronic mild stress

The present study established a mouse model of depression induced by unpredictable chronic mild stress. The model mice were treated with Yulangsan polysaccharide （YLSPS; 150, 300 and 600 mg/kg） for 21 days, and compared with fluoxetine-treated and normal control groups. Enzyme-linked immunosorbent assay, radioimmunity and immunohistochemical staining showed that following treatment with YLSPS （300 and 600 mg/kg）, monoamine neurotransmitter levels, prefrontal cortex adenylate cyclase activity and hippocampal brain-derived neurotrophic factor expression were significantly elevated, and depression-like behaviors were improved. Open-field and novelty-suppressed feeding tests showed that mouse activity levels were increased and feeding latency was shortened following treatment. Our results indicate that YLSPS inhibits depression by upregulating monoamine neurotransmitters, prefrontal cortex adenylate cyclase activity and hippocampal brain-derived neurotrophic factor expression.

A novel fluorogenic probe for monoamine oxidase assays

Monoamine oxidase is flavoenzymes, widely distributed in mammals. It is well recognized that MAOs serve an important role in metabolism that they have close relationship with health .Along with the discoveries between MAOs and neurotic disease, more and more studies have been jumped in .In this paper, we design a new probe for assaying the activities of MAOs. The results showed that the probe [7-（3-aminopropoxy）coumarin] is simple, effective and sensitive for MAOB.

Altered serous levels of monoamine neurotransmitter metabolites in patients with refractory and non-refractory depression

The study examined plasma metabolite changes of monoamine neurotransmitters in patients with treatment-resistant depression （TRD） and non-TRD before and after therapy. All 30 TRD and 30 non-TRD patients met the diagnostic criteria for a depressive episode in accordance with the International Classification of Diseases, Tenth Revision. Before treatment, and at 4, 6, and 8 weeks after treatment, the plasma metabolite products of monoamine neurotransmitters in TRD group, including 5-hydroxyindoleacetic acid, 3-methoxy-4-hydroxyphenyl ethylene glycol and homovanillic acid, were significantly lower than those in the non-TRD group. After two types of anti-depressive therapy with 5-serotonin and norepinephrine reuptake inhibitor, combined with psychotherapy, the Hamilton Depression Rating Scale scores were significantly reduced in both groups of patients, and the serous levels of 5-hydroxyindoleacetic acid and 3-methoxy-4-hydroxyphenyl ethylene glycol were significantly increased. In contrast, the homovanillic acid level exhibited no significant change. The levels of plasma metabolite products of peripheral monoamine neurotransmitters in depressive patients may predict the degree of depression and the therapeutic effects of treatment.

Effects of Fuhe decoction on behaviors and monoamine neurotransmitters in different brain regions of CUMS combined with social isolation depression model rats

Objective:To investigate the effect of Fuhe decoction on the behavior and levels of monoamine neurotransmitters in different brain regions in a depression rat model induced by chronic unpredictable mild stimulation(CUMS)combined with social isolation.Methods:Fifty male SD rats were randomly divided into a blank group,model group,fluoxetine group,Chaiqinwendan decoction group,and Fuhe decoction group.Chronic unpredictable mild stimulation combined with a social isolation method was used to replicate the depression rat model.After 42 days of administration,a tail suspension test and high-performance liquid electrochemical detection(HPLC-ECD)were used to detect the behavioral changes and changes in the content of monoamine neurotransmitters norepinephrine(NE),dopamine(DA),5-hydroxytrytamine(5-HT),and metabolites in different brain regions of rats in each group before and after treatment.Results:Compared with the model group,the epinephrine(E)content in the Fuhe decoction group was highly significantly increased(P<.01).Compared with the model group,the 5-HT content of the prefrontal cortex in rats in the Fuhe decoction group was highly significantly increased(P<.01).Furthermore,compared with the model group,the 5-HT content in the hippocampus of rats in the Fuhe decoction group was significantly increased(P<.05).Conclusion:Fuhe decoction can improve the depression-like behaviors of model rats,and its antidepressant effect may be related to the increase in 5-HT content in the prefrontal cortex and hippocampus of rats.

Effects of Acupuncture on Monoamine Neurotransmitters in Raphe Nuclei in Obese Rats

Effects of acupuncture on the levels of neurotransmitters in the raphe nuclei were investigated in obeserats.It was found that the levels of tryptophan (Trp) and 5-hydroxyindoleacetic acid (5-HIAA) wereincreased,and 5-hydroxytryptamine (5-HT) level and 5-HT/5-HIAA ratio decreased in the raphe nucleiof the obese group as compared with the normal group;and that acupuncture could produce weightreduction,increase the 5-HT level and 5-HT/5-HIAA ratio,and decrease the contents of Trp and5-HIAA,but did not change the levels of dopamine (DA) and noradrenaline (NA).It is indicated thatbenign regulative action of acupuncture on 5-HT and its metabolism in the raphe nuclei is possibly oneof the factors for reducing weight by acupuncture.

EFFECTS OF TRANSIENT FOREBRAIN ISCHEMIA AND RADIX SALVIAE MILTIORRHIZAE (RSM) ON EXTRACELLULAR LEVELS OF MONOAMINE NEUROTRANSMITTERS AND METABOLITES IN THE GERBIL STRIATUM-An in vivo Microdialysis Study

The aim of this study was to investigate the effect of 30 min forebrain ischemia, followed by 120 min reperfusion on extracellular fluid (ECF) levels of dopamine (DA), norepinephrine (NE), serotonin (5-HT) and their metabolites, homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the striatum of gerbils, so as to obtain further information on the mechanism of Radix Salviae Miltiorrhizae (RSM)-induced neuroprotection. Microdialysis was used to sample the extracellular space. Dialysate was measured by high performance liquid chromatography with electrochemical detector (HPLC-ED). ECF DA, NE levels increased from basal levels by 282, 227 and 221 folds, by 9.14, 8.51 and 8.25 folds, respectively for the three ischemic duration (0-10; 11-20; 21-30 min). ECF DA, NE, 5-HT levels in the RSM-treated group were significantly decreased as compared with those in the control group during ischemia (P

Preliminary in vitro evaluation of neuroprotective and monoamine oxidase type B inhibitory effects of newly synthesized 8-aminocaffeines

The expected growth of the elderly population at highest risk for Parkinson’s disease(PD)in the next decades makes the identification of factors that promote or prevent the disease an important goal.In addition,new therapies-aiming to delay the progression of PD are also needed(Prediger,2010).However,there have been few clinical trials designed to investigate neuroprotection.Thus the application of an appropriate in vitro model such as the neuroblastoma SH-SY5Y cell line is extremely helpful.These cells were selected due to its human origin,catecholaminergic neuronal properties,and ease of maintenance(Xicoy et al.,2017).

Alterations of Monoamine Metabolites and Neurobehavioral Function in Lead-Exposed Workers

Neurobehavioral and neurochemical effects of occupational lead exposure were invstigated by WHO Ncurobehavioral Core Test Battery (NCTB) testing and a serics of monoamine neurotransmitters and their metabolites analyzing in workers from lead smeltery and storage-battery manufacturing factory and matched controls. Indicators of lead exposure, the blood lead (PbB) and zinc protophorphyrin (ZPP) levels were found significantly higher in the expeed group compared with that of the controls (70.55μg/dL vs 3.6μg/dL; and 294.92 μg/dL vs 38.32μg/dL, respectively). Furthermore, elevated urinary homovanillic acid (HVA) and impairment of certain neurobehavioral performances were also found in the lead exposed wokers; the latter included attention/response speed, manual dexterity, perceptual-motor speed, visual perception/memory, and motor speed/steadiness. Positive or negative correlations were observed between certain parameters. Thus, homovanillic acid (HVA) is peitively correlated With PbB and ZPP; dopamine (DA) negatively correlated with Benton visual retention (BVR); and HVA negatively correlated with digit symbol (DSy), BVR, and pursuit aiming (PA). It is suggested that the alterations of dopamine and its metabolites HVA in urine associated with impairment of neurobehavioral function might be served as biomarkers of lead-induced neurotoxicity.

Changes in aminoacidergic and monoaminergic neurotransmission in the hippocampus and amygdala of rats after ayahuasca ingestion

AIM: To evaluate changes in neurotransmission induced by a psychoactive beverage ayahuasca in the hippocampus and amygdala of naive rats. METHODS: The level of monoamines, their main metabolites and amino acid neurotransmitters concentrations were quantified using high performance liquid chromatography(HPLC). Four groups of rats were employed: saline-treated and rats receiving 250, 500 and 800 mg/kg of ayahuasca infusion(gavage). Animals were killed 40 min after drug ingestion and the structures stored at-80 ℃ until HPLC assay. The data from all groups were compared using Analysis of variance and Scheffé as post test and P < 0.05 was accepted as significant. RESULTS: The results showed decreased concentrations of glycine(GLY)(0.13 ± 0.03 vs 0.29 ± 0.07, P < 0.001) and γ-aminobutyric acid(GABA)(1.07 ± 0.14 vs 1.73 ± 0.25, P < 0.001) in the amygdala of rats that received 500 of ayahuasca. Animals that ingested 800 mg/kg of ayahuasca also showed a reduction of GLY level(0.11 ± 0.01 vs 0.29 ± 0.07, P < 0.001) and GABA(0.98 ± 0.06 vs 1.73 ± 0.25, P < 0.001). In the hippocampus, increased GABA levels were found in rats that received all ayahuasca doses: 250 mg/kg(1.29 ± 0.19 vs 0.84 ± 0.21, P < 0.05); 500 mg/kg(2.23 ± 038 vs 084 ± 0.21, P < 0.05) and 800 mg/kg(1.98 ± 0.92 vs 0.84 ± 0.21, P < 0.05). In addition, an increased utilization rate of all monoamines was found in the amygdala after ayahuasca administration in doses: 250 mg/kg(noradrenaline: 0.16 ± 0.02 vs 0.36 ± 0.06, P < 0.01; dopamine: 0.39 ± 0.012 vs 2.39 ± 0.84, P < 0.001; serotonin: 1.02 ± 0.22 vs 4.04 ± 0.91, P < 0.001), 500 mg/kg(noradrenaline: 0.08 ± 0.02 vs 0.36 ± 0.06, P < 0.001; dopamine: 0.33 ± 0.19 vs 2.39 ± 0.84, P < 0.001; serotonin: 0.59 ± 0.08 vs 4.04 ± 0.91, P < 0.001) and 800 mg/kg(noradrenaline: 0.16 ± 0.04 vs 0.36 ± 0.06, P < 0.001; dopamine: 0.84 ± 0.65 vs2.39 ± 0.84, P < 0.05; serotonin: 0.36 ± 0.02 vs 4.04 ± 0.91, P < 0.001). CONCLUSION: Our data suggest increased release of inhibitory amino acids by the hippocampus and an increased utilization rate of monoamines by the amygdala after different doses of ayahuasca ingestion.

INFLUENCE OF EA ON ELECTROCARDIOGRAM AND MONOAMINE TRANSMITTER AND c-Fos OF BRAIN STEM OF ACUTE MYOCARDIAL ISCHEMIA IN RATS

The present study aimed at the investigation of the changes of electrocardiogram (ECG) and monoamine transmitters in brainstem of rats with acute myocardial ischemia (AMl) with electroacupuncture (EA) at Neiguan (PC 6) and Jianshi (PC 5) treated by means of physiologic and histofluorescent and immunofluorescent methods. The results are as follows: 1. EA couId prevent ST segrnent and T wave from elevating during acute myocardial ischemia (P < 0. 05 ). 2. Monoamine-containing neurons with clear figure and bright fluoreasence, pre-and terminal axons were seen in Iocus coeruleus,lateral horn of splnal cord in two groups by the high specific sensitivity histofluorescence technique.The reaction of fluorescence was stronger in EA group than that in control one. The serotonin (5-HT) immunoreactive (ir) cells appeared in nucleus raphe (B 1, B 2). The 5-HT ir grains were more intense in EA group than that in control group. Tyrosine hydrotylase (TH) immunoreactive (ir) cell bodies were found within confines of catecholaminergic nuclei (A 1, A 2 ) of medulla. The immunofluorescence was weaker in EA group than that in control one. The results suggest that EA may regulate acute myocardial ischemia through brain stem.

CHANGES OF MONOAMINES, PURINES AND AMINO ACIDS IN RAT STRIATUM AS MEASURED BY INTERCEREBRAL MICRODIALYSIS DURING ISCHEMIA/REPERFUSION

The aim of this study was to determine the time course of changes in extracellular fluid (ECF) concentrations of purines, amino acids, monoamines, and their metabolites in the striatum of rats during ischemia and reperfusion, using intracerebral microdialysis as the sampling technique. In rats subjected to 20 min forebrain ischemia by four-vessel occlusion, the concentrations of adenosine (Ade), inosine (Ino) and hypoxanthine (Hyp) were found to rise markedly. These changes were accompanied by dramatically elevated levels of aspartate (Asp), glutamate (Glu), taurine (Tau), γ-aminobutyric acid (GABA), dopamine (DA) and norepinephrine (NE), all of which gradually returned to baseline following reperfusion. Concomitantly, the levels of metabolite 3, 4-dihydroxyphenylacetic acid (DOPAC) . homovanillic acid (HVA), 5-hydroxyindole-3-acetic acid (5-HIAA) and xanthine (Xan) decreased during ischemia and gradually recovered 60～ 90 min after reperfusion. It was concluded that during global brain ischemia, the ECF is flooded with both potentially harmful (e. g. Asp, Glu, DA) and protective (e. g. Tau, GABA, Ade) agents.

A Strategy to Employ Clitoria ternatea as a Prospective Brain Drug Confronting Monoamine Oxidase (MAO) Against Neurodegenerative Diseases and Depression

Ayurveda is a renowned traditional medicine practiced in India from ancient times and Clitoria ternatea is one such prospective medicinal herb incorporated as an essential constituent in a brain tonic called as medhya rasayan for treating neurological disorders.This work emphasises the significance of the plant as a brain drug there by upholding Indian medicine.The phytochemicals from the root extract were extricated using gas chromatography–mass spectrometry assay and molecular docking against the protein Monoamine oxidase was performed with four potential compounds along with four reference compounds of the plant.This persuades the prospect of C.ternatea as a remedy for neurodegenerative diseases and depression.The in silico assay enumerates that a major compound(Z)-9,17-octadecadienal obtained from the chromatogram with a elevated retention time of 32.99 furnished a minimum binding affinity energy value of-6.5 kcal/mol against monoamine oxidase(MAO-A).The interactions with the amino acid residues ALA 68,TYR 60 and TYR 69 were analogous to the reference compound kaempferol-3-monoglucoside with a least score of-13.90/-12.95 kcal/mol against the isoforms(MAO)A and B.This study fortifies the phytocompounds of C.ternatea as MAO-inhibitors and to acquire a pharmaceutical approach in rejuvenating Ayurvedic medicine.

A Study on Antitoxic Role of Vesicular Monoamine Transporter 2 in Transgenic Chinese Hamster Overy Cells

Objective : To study the antitoxic role of vesicular monoamine transporter 2 (VMAT2) in transgenic Chinese Hamster ovary (CHO) cell. Methods :With the technology of trans-gene from PC 12 to CHO, MTT reduction assay was used to detect MPP+ toxic effect on wild type CHO (wtCHO) and transgenic CHO. Meanwhile, the role of reserpine was also observed in MPP+ toxic effects. Results :The sensitivity of transgenic CHO to MPP+ was much less than that of wtCHO with 0. 5 mmol/L MPP+. Transgenic CHO had the same sensitivity as wtCHO if rotenone was given. WtCHO, by given reserpine alone, didn't change its sensitivity to MPP+. Conclusions :VMAT2 has protective effect on transgenic CHO by transporting MPP+ to vesicles.

DNA methylation of the Monoamine Oxidases A and B genes in postmortem brains of subjects with schizophrenia

Aims: We focused on DNA methylation of the promoter regions of the Monoamine Oxidase (MAO) A and B genes from postmortem brains of subjects with schizophrenia. Methods: We determined levels of DNA methylation using genomic DNA samples purified from four brain areas: prefrontal cortex (PFC), hippocampus, occipital cortex and nucleus accumbens (NAc), by a bisulfite sequencing method from seven normal subjects and six subjects with schizophrenia. Results: Although very few methylated CpGs of the MAOA and MAOB genes were detected in male samples, various DNA methylation patterns were present in female samples, and some differences were found in such patterns between normal subjects and subjects with schizophrenia. In the PFC, the average level of methylation of both genes was significantly higher in subjects with schizophrenia than in normal subjects. The content of highly methylated alleles of the MAOA gene in the NAc was significantly associated with schizophrenia, with similar results obtained for the MAOB gene in both the NAc and PFC. Some CpG sites showed higher levels of methylation in schizophrenia than in normal subjects. Conclusions: Levels of methylation were quite high in NAc and PFC in female subjects with schizophrenia compared with those in female normal subjects.

Association of adverse effects with monoamine oxidase type B inhibitor and catechol-o-methyl transferase inhibitor combination therapy in Parkinson’s disease patients

Currently, levodopa is the most effective and commonly used medication to control motor symptoms in Parkinson’s disease (PD). However, its long-term use is associated with adverse effects (AEs). Combination therapy of a monoamine oxidase type B inhibitor (MAOBI) with levodopa or a catechol-O-methyl transferase inhibitor (COMTI) with levodopa provides benefits to PD patients. Direct comparison of efficacy and side effect profiles is complex. The aim of this study is to investigate the different AE profiles of MAOBI and COMTI combination therapies. Data used to analyze the AEs of different PD medications were retrieved from “The Boston University Medical Center’s Parkinson’s Disease and Movement Disorder Database”. Ten categories of AEs were compared between patients receiving MAOBI and COMTI combination treatment. In total, 87 subjects were included in the analysis. Out of ten AEs, the presence of dementia was signifi- cantly different between the MAOBI and COMTI groups with an OR of 6.9 (COMTI vs MAOBI, 95% CI 1.3 - 37.0). Motor fluctuations were also found to be differently distributed in the two medication groups with an OR of 3.1 (COMTI vs MAOBI, 95% CI 1.0 - 9.8). In this retrospective database analysis of patients treated with combination treatment for PD, combination therapy of a COMTI with levodopa was more likely to be associated with dementia and motor fluctuations than a MAOBI with levodopa.

Tyramine in Malt Beverages Interfering with Monoamine Oxidase Inhibitor Drugs

The objective of this review is the determination of tyramine in 13 nonalcoholic beers (Maoshaieer) of Tehran market and survey of it’s probably interaction with monoamine oxidase inhibitor drugs (MAOIs) has been investigated. Tyramine was at the highest levels in Baltika (111.34 ± 8.19 μg/ml) and at the lowest level in Bitmalt (8.01 ± 2.09 μg/ml). Comparing different flavors of malt drinks, the highest tyramine content was shown for classic or normal flavor (average 72.99 ± 30.87 μg/ml), while the lowest value belonged to cantaloupe flavored drinks (average 10.55 ± 1.29 μg/ml). In our study, it is seen that there is a significant difference between import and Iranian non-alcoholic beers, the import ones has more tyramine than Iranians. A number of 10 kinds of 13 samples interact whit MAOIs in one serving (250 ml) usage 18.50 mg. The highest tyramine content of Iranian ones is 17.74 mg/250ml and for import ones is 27.83 mg/250ml.

Effects of routine rehabilitation therapy combined with low frequency electrical stimulation on monoamine neurotransmitters, NSE, ET-1 and cerebral hemodynamics in children with cerebral palsy

Objective:To investigate the effects of routine rehabilitation therapy combined with low frequency head stimulation on monoamine neurotransmitters, neuron-specific enolase (NSE), endothelin-1 (ET-1) and cerebral hemodynamics in children with cerebral palsy.Methods:From January 2017 to June 2018, 110 children with cerebral palsy were randomly divided into observation group (55 cases) and control group (55 cases). The control group received routine rehabilitation treatment, while the observation group received low-frequency head stimulation on the basis of routine rehabilitation treatment. The changes of dopamine (DA), norepinephrine (NE), serotonin (5-HT), NSE, ET-1 levels and mean blood flow velocity of anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA) were compared in two groups.Results:Before treatment, there was no significant difference in DA, NE and 5-HT levels in two groups. After treatment, DA, NE and 5-HT levels in the observation group were (192.23±22.71) ng/mL, (98.02±11.71) ng/L, (210.07±25.03) ng/L, and in the control group. the DA, NE, 5-HT levels were (147.06±17.02) ng/mL, (83.07±11.15) ng/L, and (171.88±20.45) ng/L, respectively. The DA, NE and 5-HT levels in two groups were higher than those before treatment, and DA, NE and 5-HT levels in the observation group were higher than those in the control group. Before treatment, there was no significant difference in NSE and ET-1 levels between the two groups. After treatment, the NSE and ET-1 levels in the observation group were (7.97±2.07) μg/L and (41.01±10.07) pg/mL, and the NSE and ET-1 levels in the control group were (10.38±3.02) μg/L, (58.46±15.02) pg/mL, respectively. the NSE and ET-1 in two groups were lower than those before treatment, and the NSE and ET-1 of the observation group were lower than the control group. Before treatment, there was no significant difference in mean blood flow velocity between ACA, MCA and PCA. After treatment, the mean blood flow velocities of ACA, MCA, and PCA in the observation group were (46.88±7.72) cm/s, (59.85±10.18) cm/s, and (49.15±7.02) cm/s, respectively, which was significantly higher than before treatment and higher than that of the control group in the same period.Conclusion: Conventional rehabilitation combined with low-frequency electrical stimulation of the head can effectively increase the content of monoamine neurotransmitters in children with cerebral palsy, enhance cerebral blood circulation, and reduce brain damage.

Two-step production of monoamines in monoenzymatic cells in the spinal cord:a different control strategy of neurotransmitter supply?

Monoamine neurotransmitters play an important role in the modulation of sensory, motor and autonomic functions in the spinal cord. Although traditionally it is believed that in mammalian spinal cord, monoamine neurotransmitters mainly originate from the brain, accumulating evidence indicates that especially when the spinal cord is injured, they can also be produced in the spinal cord. In this review, I will present evidence for a possible pathway for two-step synthesis of dopamine and serotonin in the spinal cord. Published data from different sources and unpublished data from my own ongoing projects indicate that monoenzymatic cells expressing aromatic L-amino acid decarboxylase（AADC）, tyrosine hydroxylase（TH） or tryptophan hydroxylase（TPH） are present in the spinal cord and that these TH and THP cells often lie in close proximity to AADC cells. Prompted by the above evidence, I hypothesize that dopamine and serotonin could be synthesized sequentially in two monoenzymatic cells in the spinal cord via a TH-AADC and a TPH-AADC cascade respectively. The monoamines synthesized through this pathway may compensate for lost neurotransmitters following spinal cord injury and also may play specific roles in the recovery of sensory, motor and autonomic functions.