Tyrosine Hydroxylase Levels Research Articles

Central deficiency of norepinephrine synthesis and norepinephrinergic neurotransmission contributes to seizure-induced respiratory arrest

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of mortality in patients with intractable epilepsy. However, the pathogenesis of SUDEP seems to be poorly understood. Our previous findings showed that the incidence of seizure-induced respiratory arrest (S-IRA) was markedly reduced by atomoxetine in a murine SUDEP model. Because the central norepinephrine α-1 receptor (NEα-1R) plays a vital role in regulating respiratory function, we hypothesized that the suppression of S-IRA by atomoxetine was mediated by NE/NEα-1R interactions that can be reversed by NEα-1R antagonism. We examined whether atomoxetine-mediated suppression of S-IRA evoked by either acoustic stimulation or pentylenetetrazole (PTZ) in DBA/1 mice can be reversed by intraperitoneal (IP) and intracerebroventricular (ICV) administration of prazosin, a selective antagonist of NEα-1R. The content and activity of tyrosine hydroxylase (TH), a rate-limiting enzyme for NE synthesis, in the lower brainstem was measured by ELISA. Electroencephalograms (EEG) were obtained from using the PTZ-evoked SUDEP model. In our models, atomoxetine-mediated suppression of S-IRA evoked by either acoustic stimulation or PTZ was significantly reversed by low doses of IP and ICV prazosin. Neither repetitive acoustic stimulation nor S-IRA reduced TH levels in lower brainstem. However, the enzyme activity of TH levels in lower brainstem was significantly increased by mechanical ventilation with DBA/1 mice, which makes the dying DBA/1 mice suffering from S-IRA and SUDEP recover. EEG data showed that although the protective effect of atomoxetine was reversed by prazosin, neither drug suppressed EEG activity. These data suggest that deficient synthesis of NE and norepinephrinergic neurotransmission contributed to S-IRA and that the NEα-1R is a potential therapeutic target for the prevention of SUDEP.

Neuroprotective Effects of Safflower Flavonoid Extract in 6-Hydroxydopamine-Induced Model of Parkinson's Disease May Be Related to its Anti-Inflammatory Action.

Safflower (Carthamus tinctorius. L.), a Chinese materia medica, is widely used for the treatment of cardiovascular and cerebrovascular diseases, with flavonoids being the major active components. Multiple flavonoids in safflower bind to Parkinson’s disease (PD)-related protein DJ-1. Safflower flavonoid extract (SAFE) improved behavioral indicators in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD; however, the underlying mechanisms remain unclear. We used a 6-OHDA-induced mouse model of PD and a primary neuron-astrocyte coculture system to determine the neuroprotective effects and mechanisms of SAFE. After three weeks of SAFE administration, behavioral indicators of PD mice were improved. SAFE regulated the levels of tyrosine hydroxylase (TH) and dopamine metabolism. It significantly inhibited the activation of astrocytes surrounding the substantia nigra and reduced Iba-1 protein level in the striatum of PD mice. SAFE reduced the plasma content of inflammatory factors and suppressed the activation of nod-like receptor protein 3 (NLRP3) inflammasome. In the coculture system, kaempferol 3-O-rutinoside and anhydrosafflor yellow B significantly improved neuronal survival, suppressed neuronal apoptosis, and reduced IL-1β and IL-10 levels in the medium. Thus, SAFE showed a significant anti-PD effect, which is mainly associated with flavonoid anti-inflammatory activities.

Autophagic activity of piperine on small intestine in dementia model mice with Parkinson's disease

This article is to investigate the effect of piperine on the small intestine of mice with Parkinson's disease with dementia(PDD). Ninety-six C57 BL/6 mice of SPF grade were randomly divided into 8 groups(male, 12 in each group): normal group, model group, autophagy inhibitor group(6-amino-3-methylpurine, 3 MA, 30 mg·kg~(-1)), autophagy activator group(rapamycin, 1 mg·kg~(-1)), low, medium, and high dose piperine groups(10, 20, 40 mg·kg~(-1)), and medopar group(112.5 mg·kg~(-1)). Except for the normal group, mice in each group were injected subcutaneously with reserpine(0.1 mg·kg~(-1)) once every 48 hours for 40 days. In addition, on the 20 th day of administration, except for the normal group, the mice in the other groups were subjected to bilateral common carotid artery occlusion to finally prepare PDD models. At the same time, each group was given the corresponding drug treatment once a day for 40 days. After the last administration, the behavioral changes of mice were observed by autonomic activity experiment and hot plate experiment. The expression levels of α-synuclein(α-syn) and tyrosine hydroxylase(TH) in the small intestine were detected by immunohistochemistry. The expression levels of beclin-1, microtubule-associated protein 1 light chain 3 B(LC3 B) and p62 in the small intestine were detected by immunofluorescence assay. Hematoxylin-eosin staining was used to observe the pathological morphology of small intestine tissues in each group. Enzyme-linked immunosorbent assay was adopted for detection of β-amyloid precursor protein(APP), p-tau, acetylcholine transferase(ChAT), interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α) in small intestine. Real-time fluorescent quantitative polymerase chain reaction was used to detect the expression of α-syn, TH, beclin-1, microtubule-associated protein 1 light chain 3(LC3), and p62 mRNA and mmu-miR-99 a-5 p in the small intestine. The results of this study showed that, as compared with the model group, the number of activities, the expression levels of ChAT, TH, and p62 were significantly increased in the 3 MA group, the various piperine dose groups, and the medopar group(P<0.05), and their first foot licking time was shortened; APP, p-tau, IL-6, TNF-α, α-syn, beclin-1, LC3 B and mmu-miR-99 a-5 p expression levels were significantly reduced(P<0.05). However, as compared with the model group, the number of activities, ChAT, TH, and p62 expression levels in the rapamycin group were significantly reduced(P<0.05), and the APP, p-tau, IL-6, TNF-α, α-syn, beclin-1, LC3 B and mmu-miR-99 a-5 p expression levels were significantly increased(P<0.05). As compared with the 3 MA group, the number of activities, ChAT, TH, and p62 expression levels were significantly reduced in the low and medium dose piperine groups and rapamycin group(P<0.05); howe-ver, their first foot licking time was significantly prolonged, APP, p-tau, IL-6, TNF-α, α-syn, beclin-1, LC3 B and mmu-miR-99 a-5 p expression levels were increased significantly(P<0.05). As compared with the medopar group, the number of activities, ChAT, TH, and p62 expression levels were significantly reduced in low dose piperine group and rapamycin group(P<0.05), but their first foot licking time was significantly extended, and APP, p-tau, IL-6, TNF-α, α-syn, beclin-1, LC3 B and mmu-miR-99 a-5 p expression levels were significantly increased(P<0.05). In addition, as compared with the normal group, the small intestinal epithelial cells of the model group and the rapamycin group were shed off a lot, with severe damages of intestinal mucosa as well as edema and shedding of the small intestine villi. After administration of the therapeutic interventions, the small intestinal epithelial cells of the 3 MA group, each dose group of piperine, and the medopa group were slightly damaged and the villi were slightly shed off. In summary, piperine has a protective effect on the small intestine of PDD model mice, showing reduced expression of mmu-miR-99 a-5 p, pro-inflammatory factors and autophagy factors, and the mechanism of slowing PDD pathological symptoms may be related to the inhibition of autophagy.

Astrocyte-specific deletion of the transcription factor Yin Yang 1 in murine substantia nigra mitigates manganese-induced dopaminergic neurotoxicity

Manganese (Mn)-induced neurotoxicity resembles Parkinson's disease (PD), but the mechanisms underpinning its effects remain unknown. Mn dysregulates astrocytic glutamate transporters, GLT-1 and GLAST, and dopaminergic function, including tyrosine hydroxylase (TH). Our previous in vitro studies have shown that Mn repressed GLAST and GLT-1 via activation of transcription factor Yin Yang 1 (YY1). Here, we investigated if in vivo astrocytic YY1 deletion mitigates Mn-induced dopaminergic neurotoxicity, attenuating Mn-induced reduction in GLAST/GLT-1 expression in murine substantia nigra (SN). AAV5-GFAP-Cre-GFP particles were infused into the SN of 8-week-old YY1 flox/flox mice to generate a region-specific astrocytic YY1 conditional knockout (cKO) mouse model. 3 weeks after adeno-associated viral (AAV) infusion, mice were exposed to 330 μg of Mn (MnCl2 30 mg/kg, intranasal instillation, daily) for 3 weeks. After Mn exposure, motor functions were determined in open-field and rotarod tests, followed by Western blotting, quantitative PCR, and immunohistochemistry to assess YY1, TH, GLAST, and GLT-1 levels. Infusion of AAV5-GFAP-Cre-GFP vectors into the SN resulted in region-specific astrocytic YY1 deletion and attenuation of Mn-induced impairment of motor functions, reduction of TH-expressing cells in SN, and TH mRNA/protein levels in midbrain/striatum. Astrocytic YY1 deletion also attenuated the Mn-induced decrease in GLAST/GLT-1 mRNA/protein levels in midbrain. Moreover, YY1 deletion abrogated its interaction with histone deacetylases in astrocytes. These results indicate that astrocytic YY1 plays a critical role in Mn-induced neurotoxicity in vivo, at least in part, by reducing astrocytic GLAST/GLT-1. Thus, YY1 might be a potential target for treatment of Mn toxicity and other neurological disorders associated with dysregulation of GLAST/GLT-1.

High fat diet-induced obesity causes a reduction in brain tyrosine hydroxylase levels and non-motor features in rats through metabolic dysfunction, neuroinflammation and oxidative stress

ABSTRACT Obesity is a health problem that has been associated with neuroinflammation, decreased cognitive functions and development of neurodegenerative diseases. Parkinson’s disease (PD) is a chronic neurodegenerative condition characterized by motor and non-motor abnormalities, increased brain inflammation, α-synuclein protein aggregation and dopaminergic neuron loss that is associated with decreased levels of tyrosine hydroxylase (TH) in the brain. Diet-induced obesity is a global epidemic and its role as a risk factor for PD is not clear. Herein, we showed that 25 weeks on a high-fat diet (HFD) promotes significant alterations in the nigrostriatal axis of Wistar rats. Obesity induced by HFD exposure caused a reduction in TH levels and increased TH phosphorylation at serine 40 in the ventral tegmental area. These effects were associated with insulin resistance, increased tumor necrosis factor-α levels, oxidative stress, astrogliosis and microglia activation. No difference was detected in the levels of α-synuclein. Obesity also induced impairment of locomotor activity, total mobility and anxiety-related behaviors that were identified in the open-field and light/dark tasks. There were no changes in motor coordination or memory. Together, these data suggest that the reduction of TH levels in the nigrostriatal axis occurs through an α-synuclein-independent pathway and can be attributed to brain inflammation, oxidative/nitrosative stress and metabolic disorders induced by obesity.

Establishment of animal model manifested as bladder neurogenic changes generated by bilateral pelvic nerve injury in male rats.

To establish a male rat model of neurogenic bladder after bilateral pelvic nerve injury (BPNI) and investigate the factors associated with onset of neurogenic bladder. Twenty-four 8-week-old male Sprague-Dawley rats were randomly divided into three groups (n = 8 rats per group). Rats in 4-week and 8-week nerve injury group underwent BPNI, while rats in the sham group underwent a sham operation. Bladder functional analysis were performed and then bladders tissues were harvested for morphological examination and investigating the mRNA expression levels of target genes in all rats. The bladder weight significantly increased in rats following BPNI. Functional analysis revealed non-voiding contractions and decreased detrusor contractility following BPNI, manifested as elevated post-void residual and bladder capacity while reduced maximum voiding pressure and voiding efficiency. The collagen area in bladder tissue and mRNA expression levels of target genes significantly increased at 4or 8weeks post-BPNI except Smad3. At 4weeks post-BPNI, expression levels of vesicular acetylcholine transporter were reduced, then returned to baseline at 8weeks. Expression levels of tyrosine hydroxylase were reduced at both 4 and 8weeks post-BPNI. A neurogenic bladder animal model was successfully established by performing BPNI in male rats, characterized by impaired voiding function, bladder detrusor fibrosis, and reduced neurotransmitter release.

마우스의 도파민 신경계 및 행동성에 대한 LTE 전자파 단기 노출 영향 연구

In this study, we investigated the effects of short-term Long-Term Evolution(LTE) radio-frequency electromagnetic field(RF-EMF) exposure on mouse behavior and dopamine signaling to identify the relationship between RF-EMFs and attention deficit hyperactivity disorder(ADHD). In a reverberation chamber, eight-week-old male mice were exposed to EMFs of 1,760 MHz(whole-body average specific absorption rate of 6 W/kg, 12 h/day) for five consecutive days. Behavioral tests were performed before and after the EMF exposure to evaluate the activity, attention, and memory of the mice. Neuro-positron emission tomography imaging targeting dopamine was also performed before and after the RF-EMF exposure. The protein expression levels of dopamine receptors(D1R and D2R), dopamine transporter(DAT), and tyrosine hydroxylase(TH) were analyzed in the striatum of mice. It was observed that the short-term RF-EMF exposure did not significantly affect the behavioral and dopamine signaling systems in adult mice. In this study, we optimized the behavioral test and neurological analysis of mice to investigate the effect of the RF-EMF on ADHD. Our finding can be used to investigate the relationship between RF-EMF and ADHD further under various EMF exposure conditions.

Restoring pars intermedia dopamine concentrations and tyrosine hydroxylase expression levels with pergolide: evidence from horses with pituitary pars intermedia dysfunction

BackgroundPituitary pars intermedia dysfunction (PPID) develops slowly in aged horses as degeneration of hypothalamic dopaminergic neurons leads to proliferation of pars intermedia (PI) melanotropes through hyperplasia and adenoma formation. Dopamine (DA) concentrations and tyrosine hydroxylase (TH) immunoreactivity are markedly reduced in PI tissue of PPID-affected equids and treatment with the DA receptor agonist pergolide results in notable clinical improvement. Thus, we hypothesized that pergolide treatment of PPID-affected horses would result in greater DA and TH levels in PI tissue collected from PPID-affected horses versus untreated PPID-affected horses.To test this hypothesis, pituitary glands were removed from 18 horses: four untreated PPID-affected horses, four aged and four young horses without signs of PPID, and six PPID-affected horses that had been treated with pergolide at 2 µg/kg orally once daily for 6 months. DA concentrations and TH expression levels in PI tissues were determined by high performance liquid chromatography with electrochemical detection and Western blot analyses, respectively. ResultsDA and TH levels were lowest in PI collected from untreated PPID-affected horses while levels in the pergolide treated horses were similar to those of aged horses without signs of PPID.ConclusionsThese findings provide evidence of restoration of DA and TH levels following treatment with pergolide. Equine PPID is a potential animal model of dopaminergic neurodegeneration, which could provide insight into human neurodegenerative diseases.

Deficiency of Meis1, a transcriptional regulator, in mice and worms: Neurochemical and behavioral characterizations with implications in the restless legs syndrome.

Restless legs syndrome is a sleep-related sensorimotor neurological disease affecting up to 10% of the population. Genetic analyses have identified Myeloid Ecotropic viral Integration Site 1 (MEIS1), a transcriptional regulator, to be associated with not only the restless legs syndrome but also self-reported symptoms of insomnia and sleep. This study is to determine if Meis1 deficiency in mice can lead to restless legs syndrome-like phenotypes, and if it is the case, what the underlying mechanisms are. We used two genetic model systems, Caenorhabditis elegans and mice. Egg retention assay and fluorescent reporters were used with C. elegans. For mice, we performed behavioral tests, serum and brain iron detection, qRT-PCR, western blot, immunohistochemistry, and in vitro brain-slice recording. Our results showed that with C. elegans, the function of dop-3, an orthologue of DRD2, was diminished after the knockdown of unc-62, an ortholog of MEIS1. Additionally, unc-62 knockdown led to enhanced transcription of the orthologue of tyrosine hydroxylase, cat-2. Meis1 knockout mice were hyperactive and had a rest-phase-specific increased probability of waking. Moreover, Meis1 knockout mice had increased serum ferritin and altered striatal dopaminergic and cholinergic systems. Specifically, Meis1 knockout mice showed an increased mRNA level but decreased protein level of tyrosine hydroxylase in the striatum. Furthermore, Meis1 knockout mice had increased striatal dopamine turnover and decreased spontaneous firing regularity of striatal cholinergic interneurons. Our data suggest that Meis1 knockout mice have restless legs syndrome-like motor restlessness and changes in serum ferritin levels. The symptoms may be related to dysfunctional dopaminergic and cholinergic systems.

Increased energy expenditure and activated β3-AR-cAMP-PKA signaling pathway in the interscapular brown adipose tissue of 6-OHDA-induced Parkinson's disease model rats.

To explore the possible mechanism of weight loss in Parkinson's disease (PD). Bilateral injections of 6-hydroxydopamine (6-OHDA) into substantia nigra (SN) were performed to induce the PD model rats. The rotarod test, food intake, body weight, and interscapular brown adipose tissue (IBAT) weight were recorded 6 weeks postoperation. HE staining was performed to observe the morphology of multilocular adipose cells in IBAT. Immunohistochemistry and western blot were used to determine the protein levels of tyrosine hydroxylase (TH) in the SN, and the levels of uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), phosphorylated-hormone sensitive lipase (p-HSL), HSL, TH, β3-adrenergic receptor (β3-AR), cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA) in IBAT. After treatment with 6-OHDA for 6 weeks, 6-OHDA rats exhibited decreased TH expression in SN accompanied with shortened staying time on the rotating rod. This motor impairment paralleled with no significant alteration in body mass, IBAT weight, and food intake until the end of the experimental protocol. However, the decreasing diameter of the single fat vesicle in IBAT was observed in the 6-OHDA group. Meanwhile, compared with the control group, the protein expression of UCP1, PGC-1α, p-HSL, TH, β3-AR, cAMP, and PKA in IBAT were increased significantly in the 6-OHDA group, whereas no obvious change in the expression of HSL. The present study suggested an increased energy expenditure and activation of the β3-AR-cAMP-PKA signaling pathway in the IBAT after the destruction of the dopamine system in the SN of the rat.

IGF-1 inhibits MPTP/MPP+-induced autophagy on dopaminergic neurons through the IGF-1R/PI3K-Akt-mTOR pathway and GPER.

Autophagy dysfunctions are involved in the pathogenesis of Parkinson's disease (PD). In the present study, we aimed to evaluate the involvement of G protein-coupled estrogen receptor (GPER) in the inhibitory effect of insulin-like growth factor-1 (IGF-1) against excessive autophagy in PD animal and cellular models. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment significantly induced mouse movement disorder and decreased the protein level of tyrosine hydroxylase (TH) in the substantia nigra (SN) and dopamine (DA) content in striatum. Along with the dopamine neuron injury, we observed significant upregulations of microtubule-associated light chain-3 II (LC3-II) and α-synuclein as well as a downregulation of P62 in MPTP-treated mice. These changes could be restored by IGF-1 pretreatment. Cotreatment with IGF-1R antagonist JB-1 or GPER antagonist G15 could block the neuroprotective effects of IGF-1. 1-Methy-4-phenylpyridinium (MPP+) treatment could also excessively activate autophagy along with the reduction of cell viability in SH-SY5Y cells. IGF-1 could inhibit the neurotoxicity through promoting the phosphorylation of Akt and mammalian target of rapamycin (mTOR), which could also be antagonized by JB-1 or G15. These data suggest that IGF-1 inhibits MPTP/MPP+-induced autophagy on dopaminergic neurons through the IGF-1R/PI3K-Akt-mTOR pathway and GPER.

Loss of tyrosine hydroxylase, motor deficits and elevated iron in a mouse model of phospholipase A2G6-associated neurodegeneration (PLAN)

Phospholipase A2G6-associated neurodegeneration (PLAN) is a rare early-onset monogenic neurodegenerative movement disorder which targets the basal ganglia and other regions in the central and peripheral nervous system; presenting as a series of heterogenous subtypes in patients. We describe here a B6.C3-Pla2g6m1J/CxRwb mouse model of PLAN which presents with early-onset neurodegeneration at 90 days which is analogous of the disease progression that is observed in PLAN patients. Homozygous mice had a progressively worsening motor deficit, which presented as tremors starting at 65 days and progressed to severe motor dysfunction and increased falls on the wire hang test at 90 days. This motor deficit positively correlated with a reduction in tyrosine hydroxylase (TH) protein expression in dopaminergic neurons of the substantia nigra (SN) without any neuronal loss. Fluorescence imaging of Thy1-YFP revealed spheroid formation in the SN. The spheroids in homozygous mice strongly mirrors those observed in patients and were demonstrated to correlate strongly with the motor deficits as measured by the wire hang test. The appearance of spheroids preceded TH loss and increased spheroid numbers negatively correlated with TH expression. Perls/DAB staining revealed the presence of iron accumulation within the SN of mice. This mouse model captures many of the major hallmarks of PLAN including severe-early onset neurodegeneration, a motor deficit that correlates directly to TH levels, spheroid formation and iron accumulation within the basal ganglia. Thus, this mouse line is a useful tool for further research efforts to improve understanding of how these disease mechanisms give rise to the disease presentations seen in PLAN patients as well as to test novel therapies.

From dysregulated microRNAs to structural alterations in the striatal region of METH-injected rats

Methamphetamine (METH) is a high addictive psychostimulant drug which triggers brain atrophy via neuronal degeneration. Striatum is the main part of the brain that is regarded as a key target for drug-induced damages. MiRNAs as small regulatory molecules at the post-transcriptional level play a major role in biological pathways. In this study, initially we performed behavioral assessment in METH-treated rats. Then, we examined striatal volume and dendritic length, and also the levels of tyrosine hydroxylase (TH), caspase-3 and glial fibrillary acidic protein (GFAP) were immunohistochemically assessed. Moreover, we investigated miRNA expression profiling using high-throughput small RNA-seq technology. Based on our data, METH provoked declined motor coordination, decreases in striatal volume and dendritic length along with over-activation of astrogliosis. In addition, METH treatment down-regulated TH level while it induced up-regulation of caspase-3 in the striatal region. Furthermore, according to miR-seq analysis, we found 167 deregulated miRNAs in the striatum upon METH treatment, that among them rno-let-7b-5p, rno-miR-485-5p, rno-miR-326-3p, rno-miR-34a-5p, rno-miR-3068-5p showed high miRNA-target gene interaction. Pathway analysis revealed that miRNAs and their target genes may be involved in cell apoptosis, growth, differentiation as well as synaptic plasticity associated pathways. Altogether, we can conclude that METH noticeably elicited neuro-degeneration in the dorsal striatum.

Altered dopaminergic pathways and therapeutic effects of intranasal dopamine in two distinct mouse models of autism

The dopamine (DA) system has a profound impact on reward-motivated behavior and is critically involved in neurodevelopmental disorders, such as autism spectrum disorder (ASD). Although DA defects are found in autistic patients, it is not well defined how the DA pathways are altered in ASD and whether DA can be utilized as a potential therapeutic agent for ASD. To this end, we employed a phenotypic and a genetic ASD model, i.e., Black and Tan BRachyury T+Itpr3tf/J (BTBR) mice and Fragile X Mental Retardation 1 knockout (Fmr1-KO) mice, respectively. Immunostaining of tyrosine hydroxylase (TH) to mark dopaminergic neurons revealed an overall reduction in the TH expression in the substantia nigra, ventral tegmental area and dorsal striatum of BTBR mice, as compared to C57BL/6 J wild-type ones. In contrast, Fmr1-KO animals did not show such an alteration but displayed abnormal morphology of TH-positive axons in the striatum with higher “complexity” and lower “texture”. Both strains exhibited decreased expression of striatal dopamine transporter (DAT) and increased spatial coupling between vesicular glutamate transporter 1 (VGLUT1, a label for glutamatergic terminals) and TH signals, while GABAergic neurons quantified by glutamic acid decarboxylase 67 (GAD67) remained intact. Intranasal administration of DA rescued the deficits in non-selective attention, object-based attention and social approaching of BTBR mice, likely by enhancing the level of TH in the striatum. Application of intranasal DA to Fmr1-KO animals alleviated their impairment of social novelty, in association with reduced striatal TH protein. These results suggest that although the DA system is modified differently in the two ASD models, intranasal treatment with DA effectively rectifies their behavioral phenotypes, which may present a promising therapy for diverse types of ASD.

Inhibition of Colony-Stimulating Factor 1 Receptor by PLX3397 Prevents Amyloid Beta Pathology and Rescues Dopaminergic Signaling in Aging 5xFAD Mice.

Alzheimer’s disease (AD) is a progressive neurodegenerative disease. In this study, to investigate the effect of microglial elimination on AD progression, we administered PLX3397, a selective colony-stimulating factor 1 receptor inhibitor, to the mouse model of AD (5xFAD mice). Amyloid-beta (Aβ) deposition and amyloid precursor protein (APP), carboxyl-terminal fragment β, ionized calcium-binding adaptor molecule 1, synaptophysin, and postsynaptic density (PSD)-95 levels were evaluated in the cortex and hippocampus. In addition, the receptor density changes in dopamine D2 receptor (D2R) and metabotropic glutamate receptor 5 were evaluated using positron emission tomography (PET). D2R, tyrosine hydroxylase (TH), and dopamine transporter (DAT) levels were analyzed in the brains of Tg (5xFAD) mice using immunohistochemistry. PLX3397 administration significantly decreased Aβ deposition following microglial depletion in the cortex and hippocampus of Tg mice. In the neuro-PET studies, the binding values for D2R in the Tg mice were lower than those in the wild type mice; however, after PLX3397 treatment, the binding dramatically increased. PLX3397 administration also reversed the changes in synaptophysin and PSD-95 expression in the brain. Furthermore, the D2R and TH expression in the brains of Tg mice was significantly lower than that in the wild type; however, after PLX3397 administration, the D2R and TH levels were significantly higher than those in untreated Tg mice. Thus, our findings show that administering PLX3397 to aged 5xFAD mice could prevent amyloid pathology, concomitant with the rescue of dopaminergic signaling, suggesting that targeting microglia may serve as a useful therapeutic option for neurodegenerative diseases, including AD.

β-Methylphenylalanine exerts neuroprotective effects in a Parkinson's disease model by protecting against tyrosine hydroxylase depletion.

We evaluated the neuroprotective effects of β‐methylphenylalanine in an experimental model of rotenone‐induced Parkinson's disease (PD) in SH‐SY5Y cells and rats. Cells were pre‐treated with rotenone (2.5 µg/mL) for 24 hours followed by β‐methylphenylalanine (1, 10 and 100 mg/L) for 72 hours. Cell viability, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), mitochondrial fragmentation, apoptosis, and mRNA and protein levels of tyrosine hydroxylase were determined. In a rat model of PD, dopamine (DA) and 3,4‐dihydroxyphenylacetic acid (DOPAC) levels, bradykinesia and tyrosine hydroxylase expression were determined. In rotenone–pre‐treated cells, β‐methylphenylalanine significantly increased cell viability and MMP, whereas ROS levels, apoptosis and fragmented mitochondria were reduced. β‐Methylphenylalanine significantly increased the mRNA and protein levels of tyrosine hydroxylase in SH‐SY5Y cells. In the rotenone‐induced rat model of PD, oral administration of β‐methylphenylalanine recovered DA and DOPAC levels and bradykinesia. β‐Methylphenylalanine significantly increased the protein expression of tyrosine hydroxylase in the striatum and substantia nigra of rats. In addition, in silico molecular docking confirmed binding between tyrosine hydroxylase and β‐methylphenylalanine. Our experimental results show neuroprotective effects of β‐methylphenylalanine via the recovery of mitochondrial damage and protection against the depletion of tyrosine hydroxylase. We propose that β‐methylphenylalanine may be useful in the treatment of PD.

Fas mutation reduces obesity by increasing IL-4 and IL-10 expression and promoting white adipose tissue browning

Brown adipose tissue generates heat via the mitochondrial uncoupling protein UCP1 to protect against obesity and hypothermia. Fas mutant MRL/lpr mice exhibit a significantly leaner phenotype compared to wild type MRL/MpJ mice. In this study, we evaluated the inflammatory cell population in the adipose tissue of MRL/lpr mice, which could potentially influence their lean phenotype. Furthermore, we compared beige fat activity between the MRL/MpJ and MRL/lpr mice. Fas mutation resulted in high body temperature, improved glucose tolerance, and decreased fat mass and adipocyte size. Fas mutation prevented high-fat diet-induced obesity and decreased the white adipose tissue M1:M2 ratio. When mice were fed a high-fat diet, UCP1, IL-4, IL-10, and tyrosine hydroxylase genes had significantly higher expression in Fas-mutant mice than in wild type mice. After a cold challenge, UCP1 expression and browning were also significantly higher in the Fas-mutant mice. In summary, Fas-mutant mice are resistant to high-fat diet-induced obesity due to increased IL-4 and IL-10 levels and the promotion of thermogenic protein activity and browning in their adipose tissues. STAT6 activation might contribute to M2 polarisation by increasing IL-4 and IL-10 levels while increases in M2 and tyrosine hydroxylase levels promote browning in response to Fas mutation.

Quantitative Characterization of Phenotypical Markers After Differentiation of SH-SY5Y Cells.

The human neuroblastoma cell line, SH-SY5Y, has been widely used in neuroscience research, especially in studies related to Parkinson's disease. However, differences between clones have been demonstrated, highlighting the importance to characterize the properties of this cell line carefully. The aim of this study was to characterize the phenotype of undifferentiated and differentiated SH-SY5Y cells using various differentiation protocols. A morphological and quantitative analysis of markers related to dopaminergic and cholinergic neurons, but also other phenotypes, was performed. Differentiated cells showed the typical neuronal morphology. Undifferentiated cells expressed low levels of Tyrosine Hydroxylase (TH) and higher levels of the high-affinity Choline Transporter (CHT1). Staurosporine (ST)-differentiation resulted in the highest number of THimmunoreactive cells, followed by phorbol ester Phorbol-12-Myristate-13-Acetate (PMA), whereas differentiation with Brain-Derived Neurotrophic Factor (BDNF) did not increase TH-immunoreactive cells. TH, dopamine β-hydroxylase and vesicular monoamine transporter-2 were also significantly upregulated in ST-differentiated cells compared to both undifferentiated and Retinoic Acid (RA)- differentiated cells. RA induced the highest number of CHT1-immunoreactive cells while ST- and BDNF-differentiation reduced CHT1-immunoreactive cells, indicating a decrease in the cholinergic phenotype. The presynaptic neuronal protein, α-synuclein, was significantly upregulated in RA- and ST-treated cells compared to undifferentiated cells. Ascorbic acid increased the number of CHT1-immunoreactive cells in all differentiation procedures and ST-differentiated TH-positive cells significantly. Our findings indicate that a quantitative characterization of the phenotype is crucial when using SH-SY5Y cells to study the pathogenesis or evaluate compounds for treatment of neurodegenerative diseases.

(+)4-Cholesten-3-one promotes differentiation of neural stem cells into dopaminergic neurons through TET1 and FoxA2

In this paper, we report the results of treating cells with an effective small molecule, (+)4-cholesten-3-one (PubChem CID: 91477), which can promote neural stem cell(NSC) differentiation into dopaminergic neurons. This study used rat neural stem cells stimulated with two different concentrations (7.8 μM and 78 μM) of (+)4-cholesten-3-one. Cell phenotypic analysis showed that (+)4-cholesten-3-one induced NSC differentiation into dopaminergic neurons, and the level of tyrosine hydroxylase(TH), which is specific for dopaminergic cells, was significantly increased compared with that of the drug-free control group. Furthermore, in this study, we found that this effect may be related to the transcription factor fork-head box a2 (FoxA2) and ten-eleven translocation 1 (TET1). The expression of TET1 and FoxA2 was upregulated after treatment with (+)4-cholesten-3-one. To verify the relationship between (+)4-cholesten-3-one and these genes, we found that the binding rate of TET1 and FoxA2 increased after the application of (+)4-cholesten-3-one, as confirmed by a coimmunoprecipitation (Co-IP) assay. With a small interfering RNA (siRNA) experiment, we found that only when Tet1 and Foxa2 were not silenced was the mRNA level of Th increased after (+)4-cholesten-3-one treatment. Taken together, these data show that (+)4-cholesten-3-one can promote the differentiation of NSCs into dopaminergic neurons by upregulating the expression of TET1 and FoxA2 and by increasing their binding. Thus, (+)4-cholesten-3-one may help address the application of neural stem cell replacement therapy in neurodegenerative diseases.

Neurorestorative Effects of a Novel Fas-Associated Factor 1 Inhibitor in the MPTP Model: An [18F]FE-PE2I Positron Emission Tomography Analysis Study.

Fas-associated factor 1 (FAF1), a Fas-binding protein, is implicated in neuronal cell death in Parkinson’s disease (PD). We examined the effects of a novel FAF1 inhibitor, KM-819, in dopaminergic neurons in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model using [18F]FE-PE2I positron emission tomography (PET). The MPTP model was generated with subacute MPTP treatment (20 mg/kg/day, i.p.) for 5 consecutive days in C57bl/6J mice. This study included three groups: the control group (treatment with saline only), the MPTP model group with KM-819 treatment (20 mg/kg/day p.o.) for 6 days, and the MPTP model group without KM-819 treatment. [18F]FE-PE2I PET studies were conducted in the same animals before and after MPTP with or without KM-819 treatment to monitor changes in striatal dopamine transporter activity indicated by non-displaceable binding potential (BPND) of [18F]FE-PE2I, and the expression levels of tyrosine hydroxylase were assessed using immunohistochemistry before and after KM-819 treatment. After MPTP injection, decreased striatal BPND was observed in the MPTP model group compared with the control group. Striatal BPND increased in the MPTP model group with KM-819 treatment, but not in the MPTP model group without KM-819 treatment. The tyrosine hydroxylase expression levels also significantly increased in the MPTP model group with KM-819 treatment compared with the control group. This study indicates that inhibition of the Fas-mediated cell death pathway by KM-819 has neurorestorative effects in striatal dopamine neurons in the MPTP model. Further studies would be needed to investigate the potential of KM-819 as a therapeutic drug for PD treatment.