Non-motor symptoms in multiple system atrophy: A comparative study with Parkinson's disease and progressive supranuclear palsy.

Background: Non-motor symptoms (NMS) are compulsory clinical features for the clinical diagnosis of multiple system atrophy (MSA), some of which precede motor symptoms onset. To date, few studies have systematically investigated NMS in MSA and the timing of presenting NMS as the disease progresses. Clinically, MSA is difficult to be differentiated from Parkinson's disease (PD) and progressive supranuclear palsy (PSP), and the differences in NMS between MSA and PD/PSP remain unclear. The aim of this study was to compare the burden of NMS between MSA and PD/PSP and to delineate the timing of NMS presentation relative to the onset of motor symptoms in MSA. Methods: A total of 61, 87, and 30 patients with MSA, PD, and PSP, respectively, were enrolled in this study. NMS was systematically assessed in all patients using the NMS scale (NMSS), and the onset of NMS relative to the onset of motor symptoms in MSA was investigated. Results: MSA group had higher total NMSS scores (82.15 ± 46.10) than the PD (36.14 ± 30.78) and PSP (50.30 ± 55.05) groups (p < 0.001 overall). The number distribution pattern of the NMS was significantly different among the three parkinsonian disorders (p < 0.001 overall). In total, 85.2% of patients with MSA had more than 10 NMS, which was significantly higher than PD (28.7%) and PSP (33.3%). The frequency and scores of many NMSS subdomains and symptoms were higher in MSA than in PD and PSP (all p < 0.05). Multivariate logistic regression analysis revealed that patients with fainting, lack of motivation, swallowing, and loss of sexual interest could be attributed to MSA rather than PD or PSP, while patients with loss of concentration and forgetfulness were characteristic features of PD or PSP rather than MSA. REM-sleep behavior disorder (RBD), constipation, problems having sex, and loss of sexual interest preceded the motor symptoms onset of MSA by 2.81 ± 4.51, 1.54 ± 6.32, 1.35 ± 4.70, and 0.45 ± 3.61 years, respectively. Conclusion: The NMS spectrum in MSA differs from that of PD and PSP. Patients with MSA have a higher NMS burden than patients with PD or PSP. RBD, constipation, problems having sex, and loss of sexual interest may become early diagnostic clinical markers of MSA.

Clinical Characteristics, Iron Metabolism and Neuroinflammation: New Insight into Excessive Daytime Sleepiness in Parkinson's Disease.

BACKGROUND: To investigate the clinical characteristics, iron metabolism and neuroinflammation in Parkinson's disease (PD) patients with excessive daytime sleepiness (EDS). METHODS: We studied 379 patients with PD and 30 age-matched controls. All subjects were evaluated by Epworth sleepiness scale (ESS) and a series of rating scales and were divided into PD-EDS and PD-NEDS groups according to ESS score. The concentrations of iron and iron-related proteins and inflammatory cytokines in both cerebrospinal fluid (CSF) and serum were examined. RESULTS: 1. The occurrence rate of EDS in total PD patients was 16.09%. 2. PD-EDS group had significantly severer disease stages, more severe motor and non-motor features of the disease. 3. In CSF, the concentrations of iron and IL-1ß in the PD-EDS group were significantly higher and ferritin concentration was prominently lower when compared with the PD-NEDS group and the control group; ESS score was significantly associated with high concentrations of iron and IL-1ß and low concentration of ferritin in the PD group. Iron concentration was positively correlated with IL-1ß concentration in the PD-EDS group. 4. In serum, no changes were observed in iron and iron-related proteins and inflammatory cytokines among the three groups. CONCLUSION: EDS was a common symptom in PD patients. PD patients with EDS had more severe motor and some non-motor symptoms. Overloaded iron-relevant inflammation in the brain might be an underlying mechanism of PD-EDS.

Rapid motor progression of Parkinson's disease associates with clinical and genetic variants.

INTRODUCTION: Parkinson's disease (PD) is caused by the interplay of genetic and environmental factors during brain aging. About 90 single nucleotide polymorphisms (SNPs) have been recently discovered associations with PD, but whether they associate with the clinical features of PD have not been fully addressed yet. METHODS: Clinical data of 365 patients with PD who enrolled in Parkinson's Progression Markers Initiative (PPMI) study were obtained. Patients with rapid motor progression were determined through clinical assessments over five years follow-up. In addition, genetic information of 44 targeted SNPs was extracted from the genetic database of NeuroX for the same cohort. Logistic regression was used to analyze the genetic associations with rapid motor progression of PD. RESULTS: Among 365 patients with PD, there are more male (66%) than female (34%). Seven SNPs (rs6808178, rs115185635, rs12497850, rs34311866, rs3793947, rs11060180, rs9568188) were associated with faster motor progression (p < 0.05), and only rs6808178 passed multiple comparison correction (p < 0.0011). In addition, the extended 44 SNPs with autonomic dysfunction reach a fair prediction of AUC at 0.821. CONCLUSION: Genetics and autonomic function factors contribute to the motor progression at the clinical initiation of PD.

Analyses of Clinical Features and Investigations on Potential Mechanisms in Patients with Alzheimer's Disease and Olfactory Dysfunction.

BACKGROUND: OD is common in patients with Alzheimer's disease (AD). However, the relationship between OD and clinical symptoms and the potential mechanisms of OD in AD patients are still unknown. OBJECTIVE: To explore the relationship between OD and clinical symptoms and the potential mechanisms of OD in AD patients. METHODS: We evaluated OD using the Hyposmia Rating Scale (HRS), classified patients into AD with OD (AD-OD) and AD with no OD (AD-NOD) groups, and detected the levels of free radicals and inflammatory factors, including hydroxyl radical (•OH), hydrogen peroxide (H2O2), nitric oxide, interleukin-1ß, interleukin-6, tumor necrosis factor-α, and prostaglandin E2 in serum from AD patients. RESULTS: It was shown that the scores of the Mini-Mental State Examination, Animal Fluency Test, Boston Naming Test (BNT), and Auditory Verbal Learning Test-delayed recall were all significantly lower and the score of overall activity of daily living (ADL) and instrumental ADL were significantly higher in AD-OD group than those in AD-NOD group. Compared with AD-NOD group, •OH level in serum was prominently elevated, and H2O2 level was dramatically declined in AD-OD group. In the correlation analysis, HRS score was significantly and positively correlated with the score of BNT, and negatively correlated with •OH level in serum. CONCLUSIONS: AD-OD patients suffered from severe cognitive impairment in the domain of language. Oxidative stress might be correlated with AD-OD featured by the drastically increased •OH level in serum.

Parkinson disease with constipation: clinical features and relevant factors.

Constipation is one of the most frequent non-motor symptoms of Parkinson disease (PD) and it may be ignored by PD patients, leading to this problem not to be reported in time. The relationships between constipation and demographic variables, motor symptoms and other non-motor symptoms of PD are still unknown. PD patients were evaluated by diagnostic criteria of functional constipation in Rome III and divided into PD with constipation (PD-C) and PD with no constipation (PD-NC) groups. PD patients were assessed by rating scales of motor symptoms and other non-motor symptoms, activity of daily living and quality of life. The frequency of constipation in PD patients was 61.4%, and 24.5% of PD patients had constipation before the onset of motor symptoms. PD-C group had older age and age of onset, longer disease duration, more advanced disease stage, and more severe motor symptoms and non-motor symptoms, including worse cognition and emotion, poorer sleep quality, severer autonomic symptoms, fatigue and apathy. Binary Logistic regression analysis showed that the age, H-Y stage, depression, anxiety and autonomic dysfunction increased the risk of constipation in PD patients. Constipation exerted serious impact on the activity of daily living and quality of life in PD patients.

Clinical features and dysfunctions of iron metabolism in Parkinson disease patients with hyper echogenicity in substantia nigra: a cross-sectional study.

BACKGROUND: Transcranial ultrasound is a useful tool for providing the evidences for the early diagnosis and differential diagnosis of Parkinson disease (PD). However, the relationship between hyper echogenicity in substantia nigra (SN) and clinical symptoms of PD patients remains unknown, and the role of dysfunction of iron metabolism on the pathogenesis of SN hyper echogenicity is unclear. METHODS: PD patients was detected by transcranial sonography and divided into with no hyper echogenicity (PDSN-) group and with hyper echogenicity (PDSN+) group. Motor symptoms (MS) and non-motor symptoms (NMS) were evaluated, and the levels of iron and related proteins in serum and cerebrospinal fluid (CSF) were detected for PD patients. Data comparison between the two groups and correlation analyses were performed. RESULTS: PDSN+ group was significantly older, and had significantly older age of onset, more advanced Hohen-Yahr stage, higher SCOPA-AUT score and lower MoCA score than PDSN- group (P < 0.05). Compared with PDSN- group, the levels of transferrin and light-ferritin in serum and iron level in CSF were significantly elevated (P < 0.05), but ferroportin level in CSF was significantly decreased in PDSN+ group (P < 0.05). CONCLUSIONS: PD patients with hyper echogenicity in SN are older, at more advanced disease stage, have severer motor symptoms, and non-motor symptoms of cognitive impairment and autonomic dysfunction. Hyper echogenicity of SN in PD patients is related to dysfunction of iron metabolism, involving increased iron transport from peripheral system to central nervous system, reduction of intracellular iron release and excessive iron deposition in brain.

An Investigation on the Clinical Features and Neurochemical Changes in Parkinson's Disease With Depression.

Objective: To investigate the clinical features and neurochemical changes in Parkinson's disease with depression (PD-D). Methods: A total of 478 PD patients were divided into PD-D and PD patients without depression (PD-ND) groups according to the 24-item Hamilton Depression Rating Scale (HAMD) score. Demographic variables, motor and non-motor symptoms and activities of daily living were evaluated. The independent influencing factors of PD-D were investigated via binary logistic regression analysis. The levels of neurotransmitters in cerebrospinal fluid (CSF) were measured and their correlations with HAMD score were analyzed. Results: The proportion of PD-D was 59.0%, of which 76.95, 20.92, and 2.13% had mild, moderate, and severe depression, respectively. Anxiety/somatization was the most prevalent sub-factor of HAMD in PD-D. The scores of UPDRS III, postural instability/gait difficulty (PIGD) type and the scores of 14-item Hamilton Anxiety Scale (HAMA) and 14-item Chalder Fatigue Scale (FS) were independently associated with PD-D. The levels of dopamine (DA) and 5-hydroxytryptamine (5-HT) were all significantly reduced in PD-D group compared with those in PD-ND group. HAMD scores were negatively correlated with the DA levels in CSF. Conclusions: PD patients have a high proportion of depression, mainly of mild and moderate levels. The profile of depression in PD population is subtly different from that of the general population. Motor symptoms, PIGD type, anxiety and fatigue are the significant influencing factors of PD-D. Compared to 5-HT, DA may play a more important role in PD-D.

Restless legs syndrome in Parkinson disease: Clinical characteristics, abnormal iron metabolism and altered neurotransmitters.

Relationships among clinical characteristics, iron metabolism and neurotransmitters in Parkinson disease (PD) patients with restless legs syndrome (RLS) remains unclear. We divided 218 patients into PD with and with no RLS (PD-RLS and PD-NRLS) groups by RLS-rating scale (RLS-RS) score. Motor and non-motor symptoms were rated by related scales. Iron and related proteins, and neurotransmitters in cerebrospinal fluid (CSF) and serum were measured. PD-RLS frequency was 40.37%. PD-RLS group had longer duration, higher stage and scores of motor symptoms, depression, anxiety, sleep disorders, fatigue and apathy, and increased transferrin and decreased iron, ferritin, dopamine (DA) and 5-hydroxytryptamine (5-HT) in CSF. In CSF of PD-RLS group, RLS-RS score was positively correlated with transferrin level and negatively correlated with iron and ferritin levels; RLS-RS score was negatively correlated with DA and 5-HT levels; transferrin level was negatively correlated with DA and 5-HT levels, and ferritin level was positively correlated with DA level. In serum, PD-RLS group had decreased iron and transferrin levels, which were negatively correlated with RLS-RS score. PD-RLS was common and severer in motor and some non-motor symptoms. Iron deficiency induced by its metabolism dysfunctions in peripheral and central systems might cause PD-RLS through decreasing brain DA and 5-HT.

Phenotype of postural instability/gait difficulty in Parkinson disease: relevance to cognitive impairment and mechanism relating pathological proteins and neurotransmitters.

Parkinson disease (PD) is identified as tremor-dominant (TD) and postural instability and gait difficulty (PIGD) phenotypes. The relationships between motor phenotypes and cognitive impairment and the underlying mechanisms relating pathological proteins and neurotransmitters in cerebrospinal fluid (CSF) are unknown. We evaluated the motor symptoms and cognitive function by scales, and detected the levels of pathological proteins and neurotransmitters in CSF. TD group and PIGD group had significantly higher levels of total tau, tau phosphorylated at the position of threonine 181(P-tau181t), threonine 231, serine 396, serine 199 and lower ß amyloid (Aß)1-42 level in CSF than those in control group; PIGD group had significantly higher P-tau181t level and lower Aß1-42 level than those in TD group. In PD group, PIGD severity was negatively correlated with MoCA score and Aß1-42 level in CSF, and positively correlated with Hoehn-Yahr stage and P-tau181t level in CSF. In PIGD group, PIGD severity was negatively correlated with homovanillic acid (HVA) level in CSF, and HVA level was positively correlated with Aß1-42 level in CSF. PIGD was significantly correlated with cognitive impairment, which underlying mechanism might be involved in Aß1-42 aggregation in brain and relevant neurochemical disturbance featured by the depletion of HVA in CSF.

Nonmotor symptoms in patients with Parkinson disease: A cross-sectional observational study.

Parkinson disease (PD) is usually accompanied by numerous nonmotor symptoms (NMS), such as neuropsychiatric symptoms, sleep disorders, autonomic dysfunctions, and sensory disturbances. However, it is not clear that the factors influencing the occurrence of NMS and its sequence with motor symptoms (MS).We conducted comprehensive assessments of NMS by using 13 scales in 1119 PD patients.A total of 70.8% PD patients present NMS. Olfactory dysfunction tends to occur in PD patients with older age, more severe depression, sleep problems, and autonomic dysfunctions. Older patients are more likely to have olfactory dysfunction before MS than younger patients. Rapid eye movement behavior disorder is more prone to happen in patients with older age, older onset age, more severe depression, sleep problems, and autonomic dysfunctions. Patients with rapid eye movement behavior disorder before MS are older in onset age than after group.Olfactory dysfunction, constipation, rapid eye movement behavior disorder, and depression, as early warning NMSs of PD, connected to each other. There is a clinical heterogeneity that older patients are more likely to have NMS before MS, while younger patients are opposite.

Excessive Iron and α-Synuclein Oligomer in Brain are Relevant to Pure Apathy in Parkinson Disease.

OBJECTIVES: To investigate the demographic features, clinical features, and potential mechanism in patients with Parkinson disease (PD) with pure apathy. METHOD: A total of 145 patients with PD without depression and dementia and 30 age-matched controls were consecutively recruited. Patients with PD were evaluated by Apathy Scale (AS), scales for motor symptoms and quality of life. The levels of iron, oxidative and neuroinflammatory factors, α-synuclein oligomer, and dopamine in cerebrospinal fluid (CSF) from patients with PD and controls were detected by enzyme-linked immunosorbent assay, chemical colorimetric method, and high-performance liquid chromatography. Comparisons between PD with pure apathy and with no pure apathy groups and correlation between AS score and the levels of above factors were analyzed. RESULTS: There were 64 (44.14%) cases in PD-apathy group. The PD-apathy group had older age, (97.81 ± 10.82) years versus (61.86 ± 10.80) years, and severer quality of life (P < .05). The PD-apathy and PD without apathy groups presented no remarkable differences in motor symptoms (P > .05). The levels of iron, hydroxyl radical (·OH), hydrogen peroxide (H2O2), and α-synuclein oligomer in CSF in PD-apathy group were significantly higher than that in PD without the apathy group (P < .05). In patients with PD, the AS score was positively correlated with the levels of iron, ·OH, H2O2 and α-synuclein oligomer in CSF (r = 19.838, .063, 1.046, and 0.498, respectively, P < .05). In PD-apathy group, iron level was positively correlated with ·OH level (r = .011, P < .05), and H2O2 level was positively correlated with α-synuclein oligomer level in CSF (r = .045, P < .05). CONCLUSION: Patients with PD had high prevalence of pure apathy. Patients with PD having pure apathy had older age. Pure apathy reduced quality of life for patients without worsening motor function. Excessive iron and α-synuclein oligomer in brain commonly contributed to pure apathy of PD through potential mechanism of oxidative stress.

Parkinson's Disease with Fatigue: Clinical Characteristics and Potential Mechanisms Relevant to α-Synuclein Oligomer.

BACKGROUND AND PURPOSE: The aim of this study was to identify the clinical characteristics and potential mechanisms relevant to pathological proteins in Parkinson's disease (PD) patients who experience fatigue. METHODS: PD patients (n=102) were evaluated using a fatigue severity scale and scales for motor and nonmotor symptoms. The levels of three pathological proteins-α-synuclein oligomer, ß-amyloid (Aß)1₋42, and tau-were measured in 102 cerebrospinal fluid (CSF) samples from these PD patients. Linear regression analyses were performed between fatigue score and the CSF levels of the above-listed pathological proteins in PD patients. RESULTS: The frequency of fatigue in the PD patients was 62.75%. The fatigue group had worse motor symptoms and anxiety, depression, and autonomic dysfunction. The CSF level of α-synuclein oligomer was higher and that of Aß1₋42 was lower in the fatigue group than in the non-fatigue group. In multiple linear regression analyses, fatigue severity was significantly and positively correlated with the α-synuclein oligomer level in the CSF of PD patients, after adjusting for confounders. CONCLUSIONS: PD patients experience a high frequency of fatigue. PD patients with fatigue have worse motor and part nonmotor symptoms. Fatigue in PD patients is associated with an increased α-synuclein oligomer level in the CSF.

Serotonergic dysfunctions and abnormal iron metabolism: Relevant to mental fatigue of Parkinson disease.

Fatigue is a very common non-motor symptom in Parkinson disease (PD) patients. It included physical fatigue and mental fatigue. The potential mechanisms of mental fatigue involving serotonergic dysfunction and abnormal iron metabolism are still unknown. Therefore, we evaluated the fatigue symptoms, classified PD patients into fatigue group and non-fatigue group, and detected the levels of serotonin, iron and related proteins in CSF and serum. In CSF, 5-HT level is significantly decreased and the levels of iron and transferrin are dramatically increased in fatigue group. In fatigue group, mental fatigue score is negatively correlated with 5-HT level in CSF, and positively correlated with the scores of depression and excessive daytime sleepiness, and disease duration, also, mental fatigue is positively correlated with the levels of iron and transferrin in CSF. Transferrin level is negatively correlated with 5-HT level in CSF. In serum, the levels of 5-HT and transferrin are markedly decreased in fatigue group; mental fatigue score exhibits a negative correlation with 5-HT level. Thus serotonin dysfunction in both central and peripheral systems may be correlated with mental fatigue through abnormal iron metabolism. Depression, excessive daytime sleepiness and disease duration were the risk factors for mental fatigue of PD.

Investigation on Abnormal Iron Metabolism and Related Inflammation in Parkinson Disease Patients with Probable RBD.

OBJECTIVE: To investigate potential mechanisms involving abnormal iron metabolism and related inflammation in Parkinson disease (PD) patients with probable rapid eye movement sleep behavior disorder (PRBD). METHODS: Total 210 PD patients and 31 controls were consecutively recruited. PD patients were evaluated by RBD Screening Questionnaire (RBDSQ) and classified into PRBD and probable no RBD (NPRBD) groups. Demographics information were recorded and clinical symptoms were evaluated by series of rating scales. Levels of iron and related proteins and inflammatory factors in cerebrospinal fluid (CSF) and serum were detected. Comparisons among control, NPRBD and PRBD groups and correlation analyses between RBDSQ score and levels of above factors were performed. RESULTS: (1) The frequency of PRBD in PD patients is 31.90%. (2) PRBD group has longer disease duration, more advanced disease stage, severer motor symptoms and more non-motor symptoms than NPRBD group. (3) In CSF, levels of iron, transferrin, NO and IL-1ß in PRBD group are prominently increased. RBDSQ score is positively correlated with the levels of iron, transferrin, NO and IL-1ß in PD group. Iron level is positively correlated with the levels of NO and IL-1ß in PD group. (4) In serum, transferrin level is prominently decreased in PRBD group. PGE2 level in PRBD group is drastically enhanced. RBDSQ score exhibits a positive correlation with PGE2 level in PD group. CONCLUSIONS: PRBD is common in PD patients. PRBD group has severer motor symptoms and more non-motor symptoms. Excessive iron in brain resulted from abnormal iron metabolism in central and peripheral systems is correlated with PRBD through neuroinflammation.

Methylone-induced hyperthermia and lethal toxicity: role of the dopamine and serotonin transporters.

Methylone (2-methylamino-1-[3,4-methylenedioxy-phenyl]propan-1-one), an amphetamine analog, has emerged as a popular drug of abuse worldwide. Methylone induces hyperthermia, which is thought to contribute toward the lethal consequences of methylone overdose. Methylone has been assumed to induce hyperthermic effects through inhibition of serotonin and/or dopamine transporters (SERT and DAT, respectively). To examine the roles of each of these proteins in methylone-induced toxic effects, we used SERT and DAT knockout (KO) mice and assessed the hyperthermic and lethal effects caused by a single administration of methylone. Methylone produced higher rates of lethal toxicity compared with other amphetamine analogs in wild-type mice. Compared with wild-type mice, lethality was significantly lower in DAT KO mice, but not in SERT KO mice. By contrast, only a slight diminution in the hyperthermic effects of methylone was observed in DAT KO mice, whereas a slight enhancement of these effects was observed in SERT KO mice. Administration of the selective D1 receptor antagonist SCH 23390 and the D2 receptor antagonist raclopride reduced methylone-induced hyperthermia, but these drugs also had hypothermic effects in saline-treated mice, albeit to a smaller extent than the effects observed in methylone-treated mice. In contradistinction to 3,4-methylenedioxymethamphetamine, which induces its toxicity through SERT and DAT, these data indicate that DAT, but not SERT, is strongly associated with the lethal toxicity produced by methylone, which did not seem to be dependent on the hyperthermic effects of methylone. DAT is therefore a strong candidate molecule for interventions aimed at preventing acute neurotoxic and lethal effects of methylone.

Dopamine-dependent ectodomain shedding and release of epidermal growth factor in developing striatum: target-derived neurotrophic signaling (Part 2).

Epidermal growth factor (EGF) and structurally related peptides promote neuronal survival and the development of midbrain dopaminergic neurons; however, the regulation of their production has not been fully elucidated. In this study, we found that the treatment of striatal cells with dopamine agonists enhances EGF release both in vivo and in vitro. We prepared neuron-enriched and non-neuronal cell-enriched cultures from the striatum of rat embryos and challenged those with various neurotransmitters or dopamine receptor agonists. Dopamine and a dopamine D(1) -like receptor agonist (SKF38393) triggered EGF release from neuron-enriched cultures in a dose-dependent manner. A D(2) -like agonist (quinpirole) increased EGF release only from non-neuronal cell-enriched cultures. The EGF release from striatal neurons and non-neuronal cells was concomitant with ErbB1 phosphorylation and/or with the activation of a disintegrin and metalloproteinase and matrix metalloproteinase. The EGF release from neurons was attenuated by an a disintegrin and metalloproteinase/matrix metalloproteinase inhibitor, GM6001, and a calcium ion chelator, BAPTA/AM. Transfection of cultured striatal neurons with alkaline phosphatase-tagged EGF precursor cDNA confirmed that dopamine D(1) -like receptor stimulation promoted both ectodomain shedding of the precursor and EGF release. Therefore, the activation of striatal dopamine receptors induces shedding and release of EGF to provide a retrograde neurotrophic signal to midbrain dopaminergic neurons.

Qualitative and quantitative re-evaluation of epidermal growth factor-ErbB1 action on developing midbrain dopaminergic neurons in vivo and in vitro: target-derived neurotrophic signaling (Part 1).

Although epidermal growth factor (EGF) receptor (ErbB1) is implicated in Parkinson's disease and schizophrenia, the neurotrophic action of ErbB1 ligands on nigral dopaminergic neurons remains controversial. Here, we ascertained colocalization of ErbB1 and tyrosine hydroxylase (TH) immunoreactivity and then characterized the neurotrophic effects of ErbB1 ligands on this cell population. In mesencephalic culture, EGF and glial-derived neurotrophic factor (GDNF) similarly promoted survival and neurite elongation of dopaminergic neurons and dopamine uptake. The EGF-promoted dopamine uptake was not inhibited by GDNF-neutralizing antibody or TrkB-Fc, whereas EGF-neutralizing antibody fully blocked the neurotrophic activity of the conditioned medium that was prepared from EGF-stimulated mesencephalic cultures. The neurotrophic action of EGF was abolished by ErbB1 inhibitors and genetic disruption of erbB1 in culture. In vivo administration of ErbB1 inhibitors to rat neonates diminished TH and dopamine transporter (DAT) levels in the striatum and globus pallidus but not in the frontal cortex. In parallel, there was a reduction in the density of dopaminergic varicosities exhibiting intense TH immunoreactivity. In agreement, postnatal erbB1-deficient mice exhibited similar decreases in TH levels. Although neurotrophic supports to dopaminergic neurons are redundant, these results confirm that ErbB1 ligands contribute to the phenotypic and functional development of nigral dopaminergic neurons.

Magnesium concentration in the cerebrospinal fluid of mice and its response to changes in serum magnesium concentration.

Magnesium (Mg) is essential for cell functions such as the transport of calcium and potassium ions, and modulates signal transduction, energy metabolism, and cell proliferation. Although mice have been used as models of various neurological diseases of humans, and for investigating the therapeutic effects of Mg, neither the normal concentration of Mg in cerebrospinal fluid (CSF), nor its response to alteration of the serum level of Mg has yet been reported. The present study investigated the normal Mg concentration in the CSF of C57BL/6J (B6) and ICR mice and its response to elevation of the serum Mg level in B6 mice. In B6 mice, the normal Mg concentration in the CSF was 0.89 ± 0.11 mM, being lower than that in serum, which was 1.38 ± 0.12 mM, whereas in ICR mice the corresponding values were 1.00 ± 0.12 mM and 1.10 ± 0.09 mM, respectively. No significant alteration was found in the CSF of B6 mice injected intraperitoneally with Mg, even though the serum Mg concentration was significantly increased.

Activity-dependent shedding of heparin-binding EGF-like growth factor in brain neurons.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is initially produced as a membrane-anchored precursor (pro-HB-EGF) and subsequently liberated from the cell membrane through ectodomain shedding. Here, we characterized the molecular regulation of pro-HB-EGF shedding in the central nervous system. Cultured neocortical or hippocampal neurons were transfected with the alkaline-phosphatase-tagged pro-HB-EGF gene and stimulated with various neurotransmitters. Both kainate and N-methyl-D-aspartate, but not agonists for metabotropic glutamate receptors, promoted pro-HB-EGF shedding and HB-EGF release, which were attenuated by an exocytosis blocker and metalloproteinase inhibitors. In the brain of transgenic mice over-expressing human pro-HB-EGF, kainate-induced seizure activity decreased content of pro-HB-EGF-like immunoreactivity and conversely increased levels of soluble HB-EGF. There was concomitant phosphorylation of EGF receptors (ErbB1) following seizures, suggesting that seizure activities liberated HB-EGF and activated neighboring ErbB1 receptors. Therefore, we propose that glutamatergic neurotransmission in the central nervous system plays a crucial role in regulating ectodomain shedding of pro-HB-EGF.

Differential distributions of peptides in the epidermal growth factor family and phosphorylation of ErbB 1 receptor in adult rat brain.

Using two-site enzyme immunoassays, we measured protein levels of epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha), and heparin-binding epidermal growth factor (HB-EGF) in adult rat brain, and compared them with the phosphorylation levels of their receptor (ErbB 1). There were significant variations in the brain distributions of each ErbB 1 ligand. Among these ErbB 1 ligands, HB-EGF protein levels were higher than those of TGF alpha and those of EGF were the lowest. TGF alpha protein was relatively enriched in the midbrain regions, while HB-EGF levels were most abundant in the cerebellum. Protein distributions of the EGF family members were discordant with previously reported mRNA distributions. In addition, there was significant basal ErbB 1 phosphorylation detected with the largest amount of activation in the midbrain. These observations suggest that the activation of brain ErbB 1 involves post-translational regulation of multiple EGF family members in a region-specific manner.