Tyrosine Hydroxylase Protein Expression Research Articles

Protective role of apigenin on rotenone induced rat model of Parkinson's disease: Suppression of neuroinflammation and oxidative stress mediated apoptosis

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra which is associated with oxidative stress, neuroinflammation and apoptosis. Apigenin (AGN), a non-mutagenic flavone found in fruits and vegetables, exhibits a variety of biological effects including anti-apoptotic, anti-inflammatory, and free radical scavenging activities. The current study was aimed to investigate the neuroprotective effects and molecular mechanisms of AGN in a rat model of PD induced by rotenone (ROT). Unilateral stereotaxic intranigral infusion of ROT caused the loss of tyrosine hydroxylase (TH) immunoreactivity in striatum and substantia nigra. AGN treatment (10 and 20 mg/kg, i.p.) showed a significant improvement in behavioral, biochemical and mitochondrial enzyme activities as compared to ROT exposed rats. The mRNA expression of inflammatory markers and neurotrophic factors was quantified by reverse transcriptase polymerase chain reaction (RT-PCR). Administration of AGN significantly attenuated the upregulation of NF-κB gene expression in ROT induced group and prevented the neuroinflammation in substantia nigra pars compacta (SNpc). Further, AGN inhibited the release of pro-inflammatory cytokines TNF- α, IL-6 and pro-inflammatory enzyme iNOS-1 induced by ROT. Additionally, AGN prevents the reduction of neurotrophic factors BDNF and GDNF mRNA expression in ROT lesioned rats. Immunoblot results illustrated that AGN treatment downregulated α-synuclein aggregation and upregulated the TH protein expression as well as dopamine D2 receptor (D2R) expression in ROT lesioned rats. Thus, the present findings collectively suggest that AGN exerts its neuroprotection in ROT model of PD and may act as an effective agent for treatment of PD.

Inhibiting effects of rhynchophylline on methamphetamine-dependent zebrafish are related with the expression of tyrosine hydroxylase (TH)

In this study, to study the effect of rhynchophylline on TH in midbrain of methamphetamine-induced conditioned place preference (CPP) adult zebrafish, place preference adult zebrafish models were established by methamphetamine (40μg/g) and the expression of TH was observed by immunohistochemistry technique and Western blot. Ketamine (150μg/g), high dose of rhynchophylline (100μg/g) group can significantly reduce the place preference; immunohistochemistry results showed that the number of TH-positive neurons in midbrain was increased in the methamphetamine model group, whereas less TH-positive neurons were found in the ketamine group and high dosage rhynchophylline group. Western blot results showed that the expression of TH protein was significantly increased in the model group, whereas less expression was found in the ketamine group, high dosage rhynchophylline group. Our data pointed out that TH plays an important role in the formation of methamphetamine-induced place preference in adult zebrafish. Rhynchophylline reversed the expression of TH in the midbrain demonstrates the potential effect of mediates methamphetamine induced rewarding effect.

Saikosaponin A Alleviates Symptoms of Attention Deficit Hyperactivity Disorder through Downregulation of DAT and Enhancing BDNF Expression in Spontaneous Hypertensive Rats.

The disturbed dopamine availability and brain-derived neurotrophic factor (BDNF) expression are due in part to be associated with attention deficit hyperactivity disorder (ADHD). In this study, we investigated the therapeutical effect of saikosaponin a (SSa) isolated from Bupleurum Chinese DC, against spontaneously hypertensive rat (SHR) model of ADHD. Methylphenidate and SSa were orally administered for 3 weeks. Activity was assessed by open-field test and Morris water maze test. Dopamine (DA) and BDNF were determined in specific brain regions. The mRNA or protein expression of tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicles monoamine transporter (VMAT) was also studied. Both MPH and SSa reduced hyperactivity and improved the spatial learning memory deficit in SHRs. An increased DA concentration in the prefrontal cortex (PFC) and striatum was also observed after treating with the SSa. The increased DA concentration may partially be attributed to the decreased mRNA and protein expression of DAT in PFC while SSa exhibited no significant effects on the mRNA expression of TH and VMAT in PFC of SHRs. In addition, BDNF expression in SHRs was also increased after treating with SSa or MPH. The obtained result suggested that SSa may be a potential drug for treating ADHD.

Protective Effect of Curcumin Against Oxidative Stress-Induced Injury in Rats with Parkinson’s Disease Through the Wnt/ β-Catenin Signaling Pathway

Background/Aims: The study aimed to investigate the protective effect of curcumin against oxidative stress-induced injury of Parkinson’s disease (PD) through the Wnt/β-catenin signaling pathway in rats. Methods: The successfully established PD rat models and normal healthy rats were randomly assigned into the 6-hydroxydopamine (6-OHDA), the curcumin (Cur) and the control groups. Immunohistochemistry was used to detect the positive expression of tyrosine hydroxylase (TH), dopamine transporter (DAT) and glial fibrillary acidic protein (GFAP). Deutocerebrum primary cells were extracted and classified into the control, 6-OHDA, Cur (5, 10, 15 µmol/L), Dickkopf-1 (DKK-1) and Cur + DKK-1 groups. MTT assays, adhesion tests and TUNEL staining were used to assess cell viability, adhesion and apoptosis, respectively. Western blotting and qRT-PCR were used to examine the protein and mRNA expressions of Wnt3a and β-catenin and the c-myc and cyclinD1 mRNA expressions. Results: TH and DAT expressions in the Cur group were elevated and GFAP was reduced compared with the 6-OHDA group. Curcumin enhanced viability, survival and adhesion and attenuated apoptosis of deutocerebrum primary cells by activating the Wnt/β-catenin signaling pathway. Higher Wnt3a and β-catenin mRNA and protein expressions and c-myc and cyclinD1 mRNA expressions, enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) contents, decreased malondialdehyde (MDA) content and elevated mitochondrial membrane potential (∆ψm) were found in the 10 and 15 µmol/L Cur groups compared with the 6-OHDA group. However, opposite tendencies were found in the Cur + DKK-1 group compared to the 10 µmol/L Cur group. Conclusion: This study suggests that curcumin could protect against oxidative stress-induced injury in PD rats via the Wnt/β-catenin signaling pathway.

MIMOSA PUDICA EXERTS NEUROPROTECTION AGAINST MPP+INDUCED NEUROTOXICITY IN SHSY5Y CELL LINES-AN IN VITRO MODEL OF ANTI-PARKINSONISM

<p><strong>Objective: </strong>Parkinson’s disease (PD) is one of the of a neurodegenerative disorder, It’s decreased the dopaminergic neurones, tyrosine hydroxylase (TH) and increased the α-synuclein protein level. This study was conducted to investigate the neuroprotective effect of <em>Mimosa pudica</em> have the abilities to improve TH and DAT proteins expression against MPP<sup>+ </sup>induced neurotoxicity, in <em>in</em><em> vitro</em> model of<em> </em>Parkinson’s disease using SH-SY5Y human neuroblastoma cell lines. <strong></strong></p><p><strong>Methods: </strong><em>Mimosa pudica</em> were pre-treated with various concentration for cell viability assay. Vehicle alone or <em>Mimosa pudica</em> (300µg) for 24 h, and then were co-treated with 1000µM MPP<sup>+ </sup>for 15 min in the continued presence of vehicle or <em>Mimosa pudica</em>. After treatment, cells were collected for protein expression.<strong></strong></p><p><strong>Results: </strong>Cell viability assay confers the inhibitory concentration cell death of <em>Mimosa pudica</em>. MPP<sup>+</sup>significantly down-regulated the protein expression of<em> </em>TH (p<0.01) and DAT (p<0.05)<em>. Mimosa pudica</em> decreased the expression of α synuclein (p<0.01) in MPP<sup>+ </sup>intoxicated cell lines.</p><p><strong>Conclusion: </strong>The present study showed that <em>Mimosa pudica</em> exerts neuroprotection by suppressing α synuclein and the dopaminergic neurdegeneration. <em>Mimosa pudica</em> may be due to quecertin which might be acted via the anti-oxidant mechanism. The above finding suggests that <em>Mimosa pudica</em> may act as a potential target in the management of PD. <strong></strong></p><p> </p>

Sympathetic Hyperactivity, Increased Tyrosine Hydroxylase and Exaggerated Corpus Cavernosum Relaxations Associated with Oxidative Stress Plays a Major Role in the Penis Dysfunction in Townes Sickle Cell Mouse.

BackgroundSickle cell disease patients display priapism that may progress to erectile dysfunction. However, little is known about the pathophysiological alterations of corpus cavernosum in sickle cell disease.ObjectiveThus, this study aimed to evaluate the functional and molecular alterations of sympathetic machinery and nitric oxide—cyclic guanosine monophosphate signaling pathway in Townes transgenic sickle cell disease mice.MethodsConcentration–response curves to contractile (phenylephrine) and relaxant agents (acetylcholine and sodium nitroprusside) were obtained in corpus cavernosum strips from sickle and C57BL/6 (control) mice. Neurogenic contractions and nitrergic relaxations were obtained using electrical-field stimulation. Measurements of endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), phosphodiesterase-5 (PDE5) and α1A-, α1B- and α1D-adrenoceptor mRNA expressions and reactive-oxygen species were performed. Tyrosine hydroxylase phosphorylated at Ser-31 and total tyrosine hydroxylase protein expressions in cavernosal tissues were also measured.ResultsThe neurogenic contractions were higher in the sickle cell disease group, in association with elevated tyrosine hydroxylase phosphorylated at Ser-31 and total tyrosine hydroxylase protein expression, as well as increased tyrosine hydroxylase mRNA expression. Likewise, phenylephrine-induced contractions were greater in the sickle mice, whereas α1A-, α1B- and α1D-adrenoceptor mRNA expression remained unchanged. Cavernosal relaxations to acetylcholine, sodium nitroprusside and EFS were higher in sickle mice, accompanied by decreased eNOS and nNOS, along with lower PDE5 mRNA expression. An increase of about 40% in reactive-oxygen species generation in corpus cavernosum from sickle mice was also detected.ConclusionOur study shows that decreased nitric oxide bioavailability in erectile tissue due to increased oxidative stress leads to both sympathetic hyperactivity and dysregulation of nitric oxide signaling in corpus cavernosum from Townes sickle mice.

Effect of hyperthyroidism on circulating prolactin and hypothalamic expression of tyrosine hydroxylase, prolactin signaling cascade members and estrogen and progesterone receptors during late pregnancy and lactation in the rat

Hyperthyroidism (HyperT) compromises pregnancy and lactation, hindering suckling-induced PRL release. We studied the effect of HyperT on hypothalamic mRNA (RT-qPCR) and protein (Western blot) expression of tyrosine hydroxylase (TH), PRL receptor (PRLR) and signaling pathway members, estrogen-α (ERα) and progesterone (PR) receptors on late pregnancy (days G19, 20 and 21) and early lactation (L2) in rats. HyperT advanced pre-partum PRL release, reduced circulating PRL on L2 and increased TH mRNA (G21 and L2), p-TH, PRLR mRNA, STAT5 protein (G19 and L2), PRLR protein (G21) and CIS protein (G19). PRs mRNAs and protein decreased on G19 but afterwards PRA mRNA (G20), PRB mRNA (G21) and PRA mRNA and protein (L2) increased. ERα protein increased on G19 and decreased on G20. Thus, the altered hypothalamic PRLR, STAT5, PR and ERα expression in hyperthyroid rats may induce elevated TH expression and activation, that consequently, elevate dopaminergic tone during lactation, blunting suckling-induced PRL release and litter growth.

Acute alcohol exposure increases tyrosine hydroxylase protein expression and dopamine synthesis in zebrafish

Zebrafish have become a popular animal model for investigating the effects of alcohol on the brain and behaviour. Acute exposure to alcohol has been shown to alter dopaminergic signalling in zebrafish, but the underlying mechanisms have not been well defined. In the current study, we characterize the effects of alcohol on the zebrafish dopaminergic system by focusing on tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis. Using western blot analysis, we demonstrate that a 60min exposure to 1% alcohol increases tyrosine hydroxylase protein expression in the zebrafish brain. Enzymatic activity assays confirmed that alcohol also increases tyrosine hydroxylase enzymatic activity, whereas HPLC analysis demonstrated increased levels of whole-brain dopamine and its metabolite DOPAC. In addition to activation of the dopaminergic system, behavioural analysis revealed accompanying increase of distance traveled following 1% alcohol exposure. These findings suggest that acute alcohol exposure elevates dopamine synthesis via increased tyrosine hydroxylase protein expression. Our results support the hypothesis that alcohol alters dopaminergic signalling in the zebrafish brain in a similar manner as compared to mammals.

Neuroprotective Effects of a Standardized Flavonoid Extract from Safflower against a Rotenone-Induced Rat Model of Parkinson's Disease.

Parkinson’s disease (PD) is a major age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra par compacta (SNpc). Rotenone is a neurotoxin that is routinely used to model PD to aid in understanding the mechanisms of neuronal death. Safflower (Carthamus tinctorius. L.) has long been used to treat cerebrovascular diseases in China. This plant contains flavonoids, which have been reported to be effective in models of neurodegenerative disease. We previously reported that kaempferol derivatives from safflower could bind DJ-1, a protein associated with PD, and that a flavonoid extract from safflower exhibited neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD. In this study, a standardized safflower flavonoid extract (SAFE) was isolated from safflower and found to primarily contain flavonoids. The aim of the current study was to confirm the neuroprotective effects of SAFE in rotenone-induced Parkinson rats. The results showed that SAFE treatment increased body weight and improved rearing behavior and grip strength. SAFE (35 or 70 mg/kg/day) treatment reversed the decreased protein expression of tyrosine hydroxylase, dopamine transporter and DJ-1 and increased the levels of dopamine and its metabolite. In contrast, acetylcholine levels were decreased. SAFE treatment also led to partial inhibition of PD-associated changes in extracellular space diffusion parameters. These changes were detected using a magnetic resonance imaging (MRI) tracer-based method, which provides novel information regarding neuronal loss and astrocyte activation. Thus, our results indicate that SAFE represents a potential therapeutic herbal treatment for PD.

A Novel Model of Dexamethasone-Induced Hypertension: Use in Investigating the Role of Tyrosine Hydroxylase.

Our objective was to study hypertension induced by chronic administration of synthetic glucocorticoid, dexamethasone (DEX), under nonstressful conditions and examine the role of catecholamine biosynthesis. To achieve this, we did the following: 1) used radiotelemetry to record mean arterial pressure (MAP) and heart rate (HR) in freely moving rats, and 2) administered different doses of DEX in drinking water. To evaluate the involvement of tyrosine hydroxylase (TH), the rate-limiting step in catecholamine biosynthesis, we treated rats with the TH inhibitor, α-methyl-para-tyrosine (α-MPT), for 3 days prior to administration of DEX and assessed TH mRNA and protein expression by quantitative real-time polymerase chain reaction and Western blot in the adrenal medulla. We observed a dose-dependent elevation in blood pressure with a DEX dose of 0.3 mg/kg administered for 10 days, significantly increasing MAP by +15.0 ± 1.1 mm Hg, while concomitantly reducing HR. Although this DEX treatment also significantly decreased body weight, pair-fed animals that showed similar decreases in body weight due to lowered food intake were not hypertensive, suggesting that body weight changes may not account for DEX-induced hypertension. Chronic DEX treatment significantly increased the TH mRNA and protein levels in the adrenal medulla, and α-MPT administration not only reduced DEX pressor effects, but also inhibited TH (serine(40)) phosphorylation. Our study thus validates a novel model to study hypertension induced by chronic intake of DEX in freely moving rats not subject to the confounding factors of previous models and establishes its dependence on concomitant activation of peripheral catecholamine biosynthesis.

Regulation of Tyrosine Hydroxylase Expression and Phosphorylation in Dopamine Transporter-Deficient Mice.

Tyrosine hydroxylase (TH) and dopamine transporters (DATs) regulate dopamine (DA) neurotransmission at the biosynthesis and reuptake steps, respectively. Dysfunction or loss of these proteins occurs in impaired locomotor or addictive behavior, but little is known about the influence of DAT expression on TH function. Differences in TH phosphorylation, DA tissue content, l-DOPA biosynthesis, and DA turnover exist between the somatodendritic and terminal field compartments of nigrostriatal and mesoaccumbens pathways. We examined whether differential DAT expression affects these compartmental differences in DA regulation by comparing TH expression and phosphorylation at ser31 and ser40. In heterozygous DAT knockout (KO) (+/-) mice, DA tissue content and DA turnover were unchanged relative to wild-type mice, despite a 40% reduction in DAT protein expression. In DAT KO (-/-) mice, DA turnover increased in all DA compartments, but DA tissue content decreased (90-96%) only in terminal fields. TH protein expression and phosphorylation were differentially affected within DA pathway compartments by relative expression of DAT. TH protein decreased (∼74%), though to a significantly lesser extent than DA, in striatum and nucleus accumbens (NAc) in DAT -/- mice, with no decrease in substantia nigra or ventral tegmental area. Striatal ser31 TH phosphorylation and recovery of DA relative to TH protein expression in DAT +/- and DAT -/- mice decreased, whereas ser40 TH phosphorylation increased ∼2- to 3-fold in striatum and NAc of DAT -/- mice. These results suggest that DAT expression affects TH expression and phosphorylation largely in DA terminal field compartments, further corroborating evidence for dichotomous regulation of TH between somatodendritic and terminal field compartments of the nigrostriatal and mesoaccumbens pathways.

Atrial Heterogeneous Autonomic Neural Remodeling in Rabbits with Experimental Atrial Fibrillation and the Effect of Intervention by Rosuvastatin.

The study aimed to observe the effects of pacing on the atrial effective refractory period (AERP), inducibility of atrial fibrillation (AF), and changes of atrial autonomic neural remodeling (ANR) by rosuvastatin intervention on the acute model of rapid-pacing-induced AF. Thirty rabbits were randomly divided into a control group (C, n = 10), rapid-pacing group (P, n = 10), and rosuvastatin-intervention group (R, n = 10). AERP and inducibility of AF were measured for all groups. The sympathetic and parasympathetic nerves of left atrium, right atrium, and atrial septum labeled with tyrosine hydroxylase (TH) and choline acetyl transferase (ChAT) were detected by immunohistochemistry and Western blot. The AERP in group R was prolonged, and AF could not be induced as easily (P < 0.05). Immunohistochemistry showed that the densities and heterogeneity of TH and ChAT positive nerves of the atrium in group P were significantly higher than those in group C (ranked as right atrium > atrial septum > left atrium), whereas those in group R were decreased (P < 0.05). Western blot showed that TH and ChAT protein expression in group P was significantly increased compared with group C, but decreased in group R (P < 0.05). Persistent rapid atrial pacing can lead to heterogeneous ANR in different parts of the rabbit atrium and may cause AF, which can be reversed by rosuvastatin. The inhibitory function of rosuvastatin may be associated with its role in reversing atrial ANR.

Treadmill exercise facilitates synaptic plasticity on dopaminergic neurons and fibers in the mouse model with Parkinson’s disease

Exercise for patients with Parkinson’s disease (PD) helps to alleviate clinical symptoms such as tremor, balance instability, gait dysfunction, and rigidity. However, molecular mechanism about effect of exercise is poorly unknown. In this study, we investigated effect of exercise in synapse and dendritic spine of nigrostriatal dopaminergic neurons on mice with PD. The C57BL/6J male mice (n=40) were divided by sham group, sham-exercise treated group, 1-Methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) treated group, and MPTP-exercise treated group. For exercise treatment, the mice were put on the treadmill to run for 8m/min, 30min/day, and 5 times/week for 2 weeks. Coordination ability was checked by rota rod test. Expression of tyrosine hydroxylase (TH), synaptophysin, and post-synaptic density protein 95 (PSD-95) was confirmed at substantia nigra pars compacta (SNpc) or striatum using western blotting, or immunohistochemistry. To check dendritic spine in striatum, we used Golgi staining. The results revealed that MPTP treated group displayed poor coordination ability compared with sham group. However, MPTP-exercise treated group showed good coordination ability compared with MPTP treated group. As well as, we also found that MPTP-exercise group increases expression of synaptophysin, PSD-95, TH, and dendritic spine in nigrostriatal dopaminergic neurons and fibers than MPTP treated group (p<0.05). Our findings suggest that exercise may give beneficial effects to patients with PD by facilitating synaptic plasticity and increasing dendritic spines.

Aggregated single-walled carbon nanotubes attenuate the behavioural and neurochemical effects of methamphetamine in mice.

Methamphetamine (METH) abuse is a serious social and health problem worldwide. At present, there are no effective medications to treat METH addiction. Here, we report that aggregated single-walled carbon nanotubes (aSWNTs) significantly inhibited METH self-administration, METH-induced conditioned place preference and METH- or cue-induced relapse to drug-seeking behaviour in mice. The use of aSWNTs alone did not significantly alter the mesolimbic dopamine system, whereas pretreatment with aSWNTs attenuated METH-induced increases in extracellular dopamine in the ventral striatum. Electrochemical assays suggest that aSWNTs facilitated dopamine oxidation. In addition, aSWNTs attenuated METH-induced increases in tyrosine hydroxylase or synaptic protein expression. These findings suggest that aSWNTs may have therapeutic effects for treatment of METH addiction by oxidation of METH-enhanced extracellular dopamine in the striatum.

Acylated but not des-acyl ghrelin is neuroprotective in an MPTP mouse model of Parkinson's disease.

The gut hormone ghrelin is widely beneficial in many disease states. However, ghrelin exists in two distinctive isoforms, each with its own metabolic profile. In Parkinson's Disease (PD) acylated ghrelin administration is neuroprotective, however, the role of des‐acylated ghrelin remains unknown. In this study, we wanted to identify the relative contribution each isoform plays using the MPTP model of PD. Chronic administration of acylated ghrelin in mice lacking both isoforms of ghrelin (Ghrelin KO) attenuated the MPTP‐induced loss on tyrosine hydroxylase (TH) neuronal number and volume and TH protein expression in the nigrostriatal pathway. Moreover, acylated ghrelin reduced the increase in glial fibrillary acidic protein and Ionized calcium binding adaptor molecule 1 microglia in the substantia nigra. However, injection of acylated ghrelin also elevated plasma des‐acylated ghrelin, indicating in vivo deacetylation. Next, we chronically administered des‐acylated ghrelin to Ghrelin KO mice and observed no neuroprotective effects in terms of TH cell number, TH protein expression, glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 cell number. The lack of a protective effect was mirrored in ghrelin‐O‐acyltransferase KO mice, which lack the ability to acylate ghrelin and consequently these mice have chronically increased plasma des‐acyl ghrelin. Plasma corticosterone was elevated in ghrelin‐O‐acyltransferase KO mice and with des‐acylated ghrelin administration. Overall, our studies suggest that acylated ghrelin is the isoform responsible for in vivo neuroprotection and that pharmacological approaches preventing plasma conversion from acyl ghrelin to des‐acyl ghrelin may have clinical efficacy to help slow or prevent the debilitating effects of PD. Ghrelin exists in the plasma as acyl and des‐acyl ghrelin. We determined the form responsible for in vivo neuroprotection in a mouse model of Parkinson's disease. Although exogenous acyl ghrelin is deacylated in situ to des‐acyl, only acyl ghrelin was neuroprotective by attenuating dopamine cell loss and glial activation. Acyl ghrelin is a therapeutic option to reduce Parkinson's Disease progression. Cover Image for this issue: doi: 10.1111/jnc.13316.

Establishment of isogenic iPSCs from an individual with SCN1A mutation mosaicism as a model for investigating neurocognitive impairment in Dravet syndrome

Dravet syndrome (DS) is a severe childhood epilepsy typically caused by de novo dominant mutations in SCN1A. Although patients with DS frequently have neurocognitive abnormalities, the precise neural mechanisms responsible for their expression have not been elucidated. There are wide phenotypic differences among individuals with SCN1A mutations, suggesting that factors other than the SCN1A mutation modify the phenotype. Therefore, a well-controlled cellular model system is required to improve our understanding of the mechanisms underlying DS. Here we generated induced pluripotent stem cell (iPSC) lines from an individual with SCN1A mutation mosaicism, and separately cloned iPSC lines both with and without the SCN1A mutation. These clones theoretically have the same genetic backgrounds, except for the SCN1A gene, and should serve as an ideal pair for investigating the pathophysiology caused by SCN1A mutations. Quantitative reverse transcription-PCR and western blot analysis revealed higher tyrosine hydroxylase mRNA and protein expression levels in mutant neurons than in wild-type neurons. Moreover, dopamine concentrations in media collected from mutant neural cultures were higher than those from wild-type neural cultures. Our findings suggest that SCN1A mutation leads to changes in the dopamine system that may contribute to the behavioral abnormalities in DS.

Verbascoside promotes the regeneration of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra.

Tyrosine hydroxylase is a key enzyme in dopamine biosynthesis. Change in tyrosine hydroxylase expression in the nigrostriatal system is closely related to the occurrence and development of Parkinson's disease. Verbascoside, an extract from Radix Rehmanniae Praeparata has been shown to be clinically effective in treating Parkinson's disease. However, the underlying mechanisms remain unclear. It is hypothesized that the effects of verbascoside on Parkinson's disease are related to tyrosine hydroxylase expression change in the nigrostriatal system. Rat models of Parkinson's disease were established and verbascoside (60 mg/kg) was administered intraperitoneally once a day. After 6 weeks of verbascoside treatment, rat rotational behavior was alleviated; tyrosine hydroxylase mRNA and protein expression and the number of tyrosine hydroxylase-immunoreactive neurons in the rat right substantia nigra were significantly higher than the Parkinson's model group. These findings suggest that the mechanism by which verbascoside treats Parkinson's disease is related to the regeneration of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra.

Enhancing tyrosine hydroxylase and tryptophan hydroxylase expression and improving oxidative stress involved in the antidepressant effect of sodium valproate on rats undergoing chronic unpredicted stress.

Depression is a common worldwide mental disorder whose etiology remains unclear; there is also a lack of effective therapeutic agents. Sodium valproate (VPA) is a traditional antiepileptic drug with mood-stabilization effect and is increasingly being used to treat bipolar disorders and depression, but its antidepressant mechanism remains unknown. The aim of the present study was to investigate the possible mechanisms of antidepressant action by studying malondialdehyde level, catalase, and superoxide dismutase activities in the serum and the mRNA and protein expression of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) in the prefrontal cortex of rats exposed to chronic unpredicted stress (CUS). Male Sprague-Dawley rats were used to establish a depression model by CUS. VPA (300 mg/kg once daily) and an equivalent volume of vehicle were administered to rats by an intragastric gavage. Rat behaviors, serum malondialdehyde level, serum catalase and superoxide dismutase activities, and the mRNA and protein expressions of TH and TPH in the prefrontal cortex were determined. The results showed that VPA treatment led to a significant decrease in depression-like behaviors, improvement in oxidative stress imbalance, and enhancement of TH, TPH mRNA, and protein expression in stressed rats, but failed to show any significant changes in control rats. This could indicate that the antidepressant mechanism of VPA is perhaps linked to upregulation of TH and TPH expression and inhibition of oxidative damage in CUS rats.

Psychostimulant-Induced Testicular Toxicity in Mice: Evidence of Cocaine and Caffeine Effects on the Local Dopaminergic System.

Several organ systems can be affected by psychostimulant toxicity. However, there is not sufficient evidence about the impact of psychostimulant intake on testicular physiology and catecholaminergic systems. The aim of the present study was to further explore potential toxic consequences of chronic exposure to cocaine, caffeine, and their combination on testicular physiology. Mice were injected with a 13-day chronic binge regimen of caffeine (3x5mg/kg), cocaine (3×10mg/kg), or combined administration. Mice treated with cocaine alone or combined with caffeine showed reduced volume of the seminiferous tubule associated to a reduction in the number of spermatogonia. Cocaine-only and combined treatments induced increased lipid peroxidation evaluated by TBARS assay and decreased glutathione peroxidase mRNA expression. Importantly, caffeine-cocaine combination potentiated the cocaine-induced germ cell loss, and induced pro-apoptotic BAX protein expression and diminished adenosine receptor A1 mRNA levels. We analyzed markers of dopaminergic function in the testis and detected the presence of tyrosine hydroxylase (TH) in the cytoplasm of androgen-producing Leydig cells, but also in meiotic germs cells within seminiferous tubules. Moreover, using transgenic BAC-Drd1a-tdTomato and D2R-eGFP mice, we report for the first time the presence of dopamine receptors (DRs) D1 and D2 in testicular mouse Leydig cells. Interestingly, the presence of DRD1 was also detected in the spermatogonia nearest the basal lamina of the seminiferous tubules, which did not show TH staining. We observed that psychostimulants induced downregulation of DRs mRNA expression and upregulation of TH protein expression in the testis. These findings suggest a potential role of the local dopaminergic system in psychostimulant-induced testicular pathology.

Necrosis inhibitor-5 (NecroX-5), attenuates MPTP-induced motor deficits in a zebrafish model of Parkinson’s disease

In the present study, necrosis inhibitor-5 (NecroX-5), a novel Cyclopentylamino carboxymethylthiazolylindole (NecroX) series compound was investigated for its protective role against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in a zebrafish model of Parkinson’s disease (PD). MPTP-induced locomotor behavior was measured in zebrafish larvae and the protein expression level of tyrosine hydroxylase (TH) was estimated in zebrafish larva homogenates. MPTP (15 μM) induced a significant (p < 0.05) impairment in zebrafish larvae locomotor behavior. Treatment with NecroX-5 at various doses (3.75, 7.5 and 15 μM) significantly and dose dependently (p < 0.05) restored MPTP-induced locomotor impairments in zebrafish larvae. Further, NecroX-5 significantly attenuated the MPTP-induced decrease in zebrafish TH protein expression levels. The effects observed by NecroX-5 were almost two fold higher when compared with the antioxidant, minocycline. In conclusion, the neuroprotective activity exhibited by NecroX-5 by attenuating MPTP-induced locomotor impairments and dopaminergic TH expression in zebrafish warrants further development of NecroX-5 as a novel neuroprotectant in the treatment of neurodegenerative disorders including PD.