Tyrosine Hydroxylase Activity Research Articles

An Exploration of the Sympathetic Component of the Recurrent Laryngeal Nerve

INTRODUCTIONHigh interest in the recurrent laryngeal nerve (RLN) morphology has been dictated by the frequent iatrogenic injures that can result in multifaceted functional losses such as dysphagia, voice alteration, and breathing. Thus, RLN has been extensively studied on the macroscopic and histological levels. According to the literature, RLN is a mixed nerve carrying motor, sensory, and preganglionic parasympathetic fibers to the larynx and displays asymmetry in branching from the vagus nerve. Even though gross anastomoses between RLN and the cervical sympathetic trunk have been observed, the presence of sympathetic postganglionic fibers within RLN have not been addressed. The present study was conducted to determine if catecholaminergic fibers are present within the RLN using immunohistochemical analysis for tyrosine hydroxylase (TH).METHODSRLN samples were obtained from 19 formalin‐preserved adult human cadavers (male n=11, female n=8). Anastomoses with sympathetic structures were noted and documented before obtaining tissue samples for histological examination. Samples were collected one centimeter distal to the RLN branching site. All sections were prepared using Luxol fast blue staining to reveal the presence of myelinated and unmyelinated fibers and TH antibody staining was used to determine the presence of catecholaminergic fibers. Histological slides were then photographed and quantitative analysis of the images was conducted with ImageJ software by measuring of the effective surface area (ESA), TH‐positive, myelinated, and unmyelinated. We reported results as mean ± SEM.RESULTSNeural communications between right RLNs and sympathetic ganglia were observed in two whole‐body donors. No statistically significant differences in the number of the fascicles, ESA, myelinated, and unmyelinated fibers between right and left RLNs were found. TH‐positive fibers were detected bilaterally or unilaterally in 89.5% of examined donors. Bilateral absence of TH activity throughout the effective surface area was observed in two cases. TH‐positive nerve fiber area within the RLNs varied from 0% to 22.14% (Figure 1). The average of TH‐positive fibers on the right was 0.045 ± 0.011 mm2 (4.47% ± 1.1% of ESA) and 0.05 ± 0.015 mm2 (5.03±1.5% of ESA) on the left. A positive correlation between the number of unmyelinated fibers and TH‐positive component was found (P=0.022 and P=0.0026 on the right and left, respectfully). All parameters, such as fascicles, ESA, myelinated, unmyelinated, and TH‐positive fibers, occurred independently of age, gender, or conditions (p>0.05).CONCLUSIONSympathetic postganglionic fibers within RLN nerve exist; however, there is a considerable difference in their number between individuals. However, the origin and functions of this component are ambiguous.SIGNIFICANCEKnowledge of the sympathetic component of RLN could assist in better understanding the physiological effects and adverse responses of vagus nerve stimulation therapy and the sequala of the RLN injury.

Spontaneous changes in brain striatal dopamine synthesis and storage dynamics ex vivo reveal end-product feedback-inhibition of tyrosine hydroxylase

Synaptic events are important to define treatment strategies for brain disorders. In the present paper, freshly obtained rat brain striatal minces were incubated under different times and conditions to determine dopamine biosynthesis, storage, and tyrosine hydroxylase phosphorylation. Remarkably, we found that endogenous dopamine spontaneously accumulated during tissue incubation at 37 °C ex vivo while dopamine synthesis simultaneously decreased. We analyzed whether these changes in brain dopamine biosynthesis and storage were linked to dopamine feedback inhibition of its synthesis-limiting enzyme tyrosine hydroxylase. The aromatic-l-amino-acid decarboxylase inhibitor NSD-1015 prevented both effects. As expected, dopamine accumulation was increased with l-DOPA addition or VMAT2-overexpression, and dopamine synthesis decreased further with added dopamine, the VMAT2 inhibitor tetrabenazine or D2 auto-receptor activation with quinpirole, accordingly to the known synaptic effects of these treatments. Phosphorylation activation and inhibition of tyrosine hydroxylase on Ser31 and Ser40 with okadaic acid, Sp-cAMP and PD98059 also exerted the expected effects. However, no clear-cut association was found between dopamine feedback inhibition of its own biosynthesis and changes of tyrosine hydroxylase phosphorylation, assessed by Western blot and mass spectrometry. The later technique also revealed a new Thr30 phosphorylation in rat tyrosine hydroxylase. Our methodological assessment of brain dopamine synthesis and storage dynamics ex vivo could be applied to predict the in vivo effects of pharmacological interventions in animal models of dopamine-related disorders.

Empagliflozin attenuates neurodegeneration through antioxidant, anti-inflammatory, and modulation of α-synuclein and Parkin levels in rotenone-induced Parkinson’s disease in rats

Sodium-glucose co-transporter 2 (SGLT 2) inhibitors are a relatively new antidiabetic drug with antioxidant and anti-inflammatory properties. Therefore, this study aimed to investigate whether SGLT 2 inhibitors have a neuroprotective effect in PD. Twenty-four Wistar rats were randomized into four groups. The first one (control group) received dimethyl sulfoxide (DMSO) as a vehicle (0.2 mL/48 hr, S.C). The second group (positive control) received rotenone (ROT) (2.5 mg/kg/48 hr, S.C) for 20 successive days, whereas the third and fourth groups received empagliflozin (EMP) (1 and 2 mg/kg/day, orally), respectively. The two groups received rotenone (2.5 mg/kg/48 hr S.C) concomitantly with EMP for another 20 days on the fifth day. By the end of the experimental period, behavioral examinations were done. Subsequently, rats were sacrificed, blood samples and brain tissues were collected for analysis. ROT significantly elevated oxidative stress and proinflammatory markers as well as α-synuclein. However, dopamine (DP), antioxidants, tyrosine hydroxylase (TH), and Parkin were significantly decreased. Groups of (EMP + ROT) significantly maintained oxidative stress and inflammatory markers elevation, maintained α-synuclein and Parkin levels, and elevated TH activity and dopamine level. In both low and high doses, EMP produced a neuroprotective effect against the PD rat model, with the high dose inducinga more significant effect.

Ameliorative role of Syzygium aromaticum aqueous extract on synaptosomal tyrosine hydroxylase activity, oxidative stress parameters, and behavioral changes in lead-induced neurotoxicity in mice.

This study reports the protective role of the aqueous extract of Syzygium aromaticum (ESA) against lead (Pb)-induced neurotoxicity in mice. Thirty male mice weighing between 18g and 25g were randomly divided into five groups. (1) Group 1 (control group), (2) group 2 (Pb-test group): was administered with a solution containing 0.1% (w/v) of lead acetate (PbAc), (3) group 3 (ESA+Pb100 group): was administered with 0.1% (w/v) of PbAc followed by 100mg/kg of S. aromaticum extract by gavage, (4) group 4 (ESA+Pb200): was administered with 0.1% (w/v) of PbAc followed by 200mg/kg of S. aromaticum extract, and (5) group 5 (ESA-group): was administered with 100mg/kg of S. aromaticum. Level of lead was determined by atomic absorption spectroscopy. Cerebral cortex synaptosomes prepared from mice administered orally with lead-acetate shown a significantly increased (p<.05) in tyrosine hydroxylase and protein carbonyl level and significantly decreased (p<.05) superoxide dismutase, glutathione reductase, and glutathione transferase activities. Also, there was a significant increase in brain lead concentration level, however, it was observed that S. aromaticum significantly reduced (p<.05) the level of lead at all tested doses. S. aromaticum rescued cerebral cortex synaptosomes from lead-induced neurotoxicity by relieving oxidative stress and abating elevated tyrosine hydroxylase activity. Moreover, S. aromaticum at the different dose grade (100mg and 200mg) abrogated the loss of motor performance in mice groups induced with lead. Altogether, our findings showed that S. aromaticum possesses antioxidant and neuro-modulatory potential against lead-induced neuronal damage. PRACTICAL APPLICATIONS: Environmental pollution with heavy metals is a known public health concern and their incremental concentrations in soil and water have risen to an unprecedented degree. Lead is one of the top 10 contaminants on the WHO's list of substances of greatest public health concern that impact the brain. However, exogenous natural bioactive supplements molecules could be one of the remedies to reduce Pb-induced toxicity. Our findings indicate therefore that, S. aromaticum could be a good fit for lowering Pb neurotoxicity and could be suggested as a neuroprotective molecule against neurodegenerative diseases involving catecholaminergic dysfunction induced by metallic elements.

Exercise increases NPY/AgRP and TH neuron activity in the hypothalamus of female mice.

Recent evidence identifies a potent role for aerobic exercise to modulate the activity of hypothalamic neurons related to appetite; however, these studies have been primarily performed in male rodents. Since females have markedly different neuronal mechanisms regulating food intake, the current study aimed to determine the effects of acute treadmill exercise on hypothalamic neuron populations involved in regulating appetite in female mice. Mature, untrained female mice were exposed to acute sedentary, low- (10 m/min), moderate- (14 m/min), and high (18 m/min)-intensity treadmill exercise in a randomized crossover design. Mice were fasted 10 h before exercise, and food intake was monitored for 48 h after bouts. Immunohistochemical detection of cFOS was performed 3 h post-exercise to determine the changes in hypothalamic neuropeptide Y (NPY)/agouti-related peptide (AgRP), pro-opiomelanocortin (POMC), tyrosine hydroxylase (TH), and SIM1-expressing neuron activity concurrent with the changes in food intake. Additionally, stains for pSTAT3tyr705 and pERKthr202/tyr204 were performed to detect exercise-mediated changes in intracellular signaling. Briefly, moderate- and high-intensity exercises increased 24-h food intake by 5.9 and 19%, respectively, while low-intensity exercise had no effects. Furthermore, increases in NPY/AgRPARC, SIM1PVN, and TH neuron activity were observed 3 h after high-intensity exercise, with no effects on POMCARC neurons. While no effects of exercise on pERKthr202/tyr204 were observed, pSTAT3tyr705 was elevated specifically in NPY/AgRP neurons 3 h post-exercise. Overall, aerobic exercise increased the activity of several appetite-stimulating neuron populations in the hypothalamus of female mice, which may provide insight into previously reported sexual dimorphisms in post-exercise feeding.

In vivo study of a novel protein kinase C that mediates immunocompetence and catecholamine biosynthesis in hemocytes of Litopenaeus vannamei by using its potential competitive inhibitor, bisindolylmaleimide I

This study applied bisindolylmaleimide I (BSM), a pharmacological competitive inhibitor of protein kinase C (PKC) enzymatic activity, at 1.25 pmol shrimp−1 for 60 min to investigate the potential involvement of PKC in signal transduction pathways in the hemocytes of Litopenaeus vannamei. A novel PKC in L. vannamei (LvnPKC) was identified and characterized and was determined to be involved in mediating the neuroendocrine-immune regulatory network. The hemocytes of L. vannamei that receive BSM exhibit significantly decreased PKC activity and LvnPKC gene and protein expression levels. Furthermore, the total hemocyte count, hyaline cells, and semigranular cells increased significantly along with significant decreases in granular cells, and meanwhile, the significantly increased phenoloxidase activity, respiratory bursts, superoxide dismutase (SOD) activity, phagocytic activity, and neutrophil extracellular trap were observed; however, phagocytic activity decreased significantly. In a molecular model, the gene expressions of lipopolysaccharide- and β-1,3-glucan-binding protein, peroxinectin, cytosolic manganese SOD, mitochondrial manganese SOD, and copper/zinc SOD in the hemocytes of L. vannamei that had received BSM decreased significantly, but prophenoloxidase I increased significantly. In catecholamine biosynthesis, tyrosine, dopamine, and norepinephrine decreased significantly in the hemocytes of L. vannamei that had received BSM, and l-dihydroxyphenylalanine increased. Moreover, tyrosine hydroxylase (TH) activity increased significantly, whereas TH and dihydroxyphenylalanine decarboxylase gene expression decreased significantly. These findings suggest that BSM inhibits PKC activity in hemocytes in which LvnPKC gene and protein expression are also inhibited. Additionally, the hemocytes’ immunocompetence, including their prophenoloxidase and antioxidant systems, phagocytic activity, and catecholamine biosynthesis, was disrupted, confirming the roles of LvnPKC in mediating the neuroendocrine-immune regulatory network in hemocytes.

Structural mechanism for tyrosine hydroxylase inhibition by dopamine and reactivation by Ser40 phosphorylation

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of dopamine (DA) and other catecholamines, and its dysfunction leads to DA deficiency and parkinsonisms. Inhibition by catecholamines and reactivation by S40 phosphorylation are key regulatory mechanisms of TH activity and conformational stability. We used Cryo-EM to determine the structures of full-length human TH without and with DA, and the structure of S40 phosphorylated TH, complemented with biophysical and biochemical characterizations and molecular dynamics simulations. TH presents a tetrameric structure with dimerized regulatory domains that are separated 15 Å from the catalytic domains. Upon DA binding, a 20-residue α-helix in the flexible N-terminal tail of the regulatory domain is fixed in the active site, blocking it, while S40-phosphorylation forces its egress. The structures reveal the molecular basis of the inhibitory and stabilizing effects of DA and its counteraction by S40-phosphorylation, key regulatory mechanisms for homeostasis of DA and TH.

Glycogen synthase kinase-3 inhibition affects dopamine metabolism by decreasing tyrosine hydroxylase activity

Glycogen synthase kinase-3 inhibition affects dopamine metabolism by decreasing tyrosine hydroxylase activity

Tyrosine hydroxylase activity is regulated through the modification of the 176th cysteine residue

Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the biosynthesis of dopamine (DA), and the regulation of its activity is important for DA homeostasis. In this study, we focused on the modification of TH through a cysteine residue. We found that incubation with N-ethylmaleimide (NEM), a cysteine modification reagent, inactivated TH. The responsible cysteine was identified as Cys176 of human TH with recombinant mutant proteins. We further examined how NEM modification was affected by the states of TH. DA binding, a feedback inhibition mechanism of TH, delayed the modification and inactivation of TH by NEM. In contrast, the S40E mutant, which mimics the phosphorylation of Ser40 that suppresses DA binding and is thus considered as an active state of TH, did not affect modification and inactivation. These results suggest that the modification of Cys176 can inhibit even phosphorylated active TH. In addition, we found that DA oxides, which are generated by oxidative stress in dopaminergic neurons, reacted with TH through Cys176 and inhibited its activity, similar to NEM. These results suggest that the modification of Cys176 of TH could be involved in the mechanisms of neurotoxicity caused by DA oxides.

Zinc antagonizes iron-regulation of tyrosine hydroxylase activity and dopamine production in Drosophila melanogaster

BackgroundDopamine (DA) is a neurotransmitter that plays roles in movement, cognition, attention, and reward responses, and deficient DA signaling is associated with the progression of a number of neurological diseases, such as Parkinson’s disease. Due to its critical functions, DA expression levels in the brain are tightly controlled, with one important and rate-limiting step in its biosynthetic pathway being catalyzed by tyrosine hydroxylase (TH), an enzyme that uses iron ion (Fe2+) as a cofactor. A role for metal ions has additionally been associated with the etiology of Parkinson’s disease. However, the way dopamine synthesis is regulated in vivo or whether regulation of metal ion levels is a component of DA synthesis is not fully understood. Here, we analyze the role of Catsup, the Drosophila ortholog of the mammalian zinc transporter SLC39A7 (ZIP7), in regulating dopamine levels.ResultsWe found that Catsup is a functional zinc transporter that regulates intracellular zinc distribution between the ER/Golgi and the cytosol. Loss-of-function of Catsup leads to increased DA levels, and we showed that the increased dopamine production is due to a reduction in zinc levels in the cytosol. Zinc ion (Zn2+) negatively regulates dopamine synthesis through direct inhibition of TH activity, by antagonizing Fe2+ binding to TH, thus rendering the enzyme ineffective or non-functional.ConclusionsOur findings uncovered a previously unknown mechanism underlying the control of cellular dopamine expression, with normal levels of dopamine synthesis being maintained through a balance between Fe2+ and Zn2+ ions. The findings also provide support for metal modulation as a possible therapeutic strategy in the treatment of Parkinson’s disease and other dopamine-related diseases.

Cardioprotective Effects of Oroxylum indicum Extract Against Doxorubicin and Cyclophosphamide-Induced Cardiotoxicity.

Administration of Chemotherapeutics, especially doxorubicin (DOX) and cyclophosphamide (CPS), is commonly associated with adverse effects such as myelosuppression and cardiotoxicity. At this time, few approved therapeutic options are currently available for the management of chemotherapy-associated cardiotoxicity. Thus, identification of novel therapeutics with potent cardioprotective properties and minimal adverse effects are pertinent in treating Doxorubicin and Cyclophosphamide-induced cardiotoxicity. Oroxylum indicum extract (OIE, Sabroxy®) is a natural product known to possess several beneficial biological functions including antioxidant, anti-inflammatory and cytoprotective effects. We therefore set to investigate the cardioprotective effects of OIE against Doxorubicin and Cyclophosphamide-induced cardiotoxicity and explore the potential cardioprotective mechanisms involved. Adult male mice were treated with DOX and CPS in combination, OIE alone, or a combination of OIE and DOX & CPS. Swimming test was performed to assess cardiac function. Markers of oxidative stress were assessed by levels of reactive oxygen species (ROS), nitrite, hydrogen peroxide, catalase, and glutathione content. The activity of interleukin converting enzyme and cyclooxygenase was determined as markers of inflammation. Mitochondrial function was assessed by measuring Complex-I activity. Apoptosis was assessed by Caspase-3 and protease activity. Mice treated with DOX and CPS exhibited reduced swim rate, increased oxidative stress, increased inflammation, and apoptosis in the heart tissue. These cardiotoxic effects were significantly reduced by co-administration of OIE. Furthermore, computational molecular docking studies revealed potential binding of DOX and CPS to tyrosine hydroxylase which validated our in vivo findings regarding the inhibition of tyrosine hydroxylase activity. Our current findings indicated that OIE counteracts Doxorubicin and Cyclophosphamide-induced cardiotoxicity-through inhibition of ROS-mediated apoptosis and by blocking the effect on tyrosine hydroxylase. Taken together, our findings suggested that OIE possesses cardioprotective effects to counteract potentially fatal cardiac complications associated with chemotherapy treatment.

Cardiac tyrosine hydroxylase activation and MB-COMT in dyskinetic monkeys

The impact of age-associated disorders is increasing as the life expectancy of the population increments. Cardiovascular diseases and neurodegenerative disorders, such as Parkinson’s disease, have the highest social and economic burden and increasing evidence show interrelations between them. Particularly, dysfunction of the cardiovascular nervous system is part of the dysautonomic symptoms of Parkinson’s disease, although more studies are needed to elucidate the role of cardiac function on it. We analyzed the dopaminergic system in the nigrostriatal pathway of Parkinsonian and dyskinetic monkeys and the expression of some key proteins in the metabolism and synthesis of catecholamines in the heart: total and phosphorylated (phospho) tyrosine hydroxylase (TH), and membrane (MB) and soluble (S) isoforms of catechol-O-methyl transferase (COMT). The dopaminergic system was significantly depleted in all MPTP-intoxicated monkeys. MPTP- and MPTP + L-DOPA-treated animals also showed a decrease in total TH expression in both right (RV) and left ventricle (LV). We found a significant increase of phospho-TH in both groups (MPTP and MPTP + L-DOPA) in the LV, while this increase was only observed in MPTP-treated monkeys in the RV. MB-COMT analysis showed a very significant increase of this isoform in the LV of MPTP- and MPTP + L-DOPA-treated animals, with no significant differences in S-COMT levels. These data suggest that MB-COMT is the main isoform implicated in the cardiac noradrenergic changes observed after MPTP treatment, suggesting an increase in noradrenaline (NA) metabolism. Moreover, the increase of TH activity indicates that cardiac noradrenergic neurons still respond despite MPTP treatment.

Effect of Itrifal Muqawwi-e-Dimagh (a polyherbal drug) on the transgenic Drosophila model of Parkinson's Disease

BackgroundParkinson's Disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta of the mid brain which leads to the depletion of dopamine levels. The depletion of dopamine leads to the motor dysfunction characterized by tremors, rigidity, bradykinesia and postural instability. In this context, the effect of unani herbal formulation Itrifal Muqawwi-e-Dimagh (IMD) was studied on the transgenic Drosophila melanogaster expressing human alpha synuclein in the neurons of flies. IMD is recommended for enhancing mental power and to treat mental illness in the Unani system of medicine. IMD was prepared as per the standard procedures and was subjected to various physico-chemical tests. MethodsThe equivalents of recommended dose for human were established for 20 g of fly food i.e. 0.0014, 0.0028, 0.0042 and 0.0056 g per 20 g of diet. The PD flies were allowed to feed on it for 24 days before performing the assays. ResultsThe PD flies exposed to IMD showed increase in the life span and improvement in the activity. A significant dose dependent delay in the loss of climbing ability was observed in PD flies exposed to various doses of IMD. The exposure of PD flies to IMD showed a significant reduction in the oxidative stress and increase in the anti-oxidant enzymes compared to unexposed PD flies. The PD flies exposed to various doses of IMD showed a significant dose dependent increase in the activity of tyrosine hydroxylase as evident by immunohistochemistry. ConclusionIt is concluded that IMD is potent in reducing the PD symptoms being mimicked in the transgenic Drosophila.

Activation of locus coeruleus to rostromedial tegmental nucleus (RMTg) noradrenergic pathway blunts binge-like ethanol drinking and induces aversive responses in mice

There is strong evidence that ethanol entails aversive effects that can act as a deterrent to overconsumption. We have found that in doses that support the development of a conditioned taste aversion ethanol increases the activity of tyrosine hydroxylase (TH) positive neurons in the locus coeruleus (LC), a primary source of norepinephrine (NE). Using cre-inducible AAV8-ChR2 viruses in TH-ires-cre mice we found that the LC provides NE projections that innervate the rostromedial tegmental nucleus (RMTg), a brain region that has been implicated in the aversive properties of drugs. Because the neurocircuitry underlying the aversive effects of ethanol is poorly understood, we characterized the role of the LC to RMTg circuit in modulating aversive unconditioned responses and binge-like ethanol intake. Here, both male and female TH-ires-cre mice were cannulated in the RMTg and injected in the LC with rAVV viruses that encode for a Gq-expressing designer receptor exclusively activated by designer drugs (DREADDs) virus, or its control virus, to directly control the activity of NE neurons. A Latin Square paradigm was used to analyze both 20% ethanol and 3% sucrose consumption using the “drinking-in-the-dark” (DID) paradigm. Chemogenetic activation of the LC to RMTg pathway significantly blunted the binge-ethanol drinking, with no effect on the sucrose consumption, increased the emission of mid-frequency vocalizations and induced malaise-like behaviors in mice. The present findings indicate an important involvement of the LC to RMTg pathway in reducing ethanol consumption, and characterize unconditioned aversive reactions induced by activation of this noradrenergic pathway.This article is part of the special Issue on ‘Neurocircuitry Modulating Drug and Alcohol Abuse'.

Post-translational and post-transcriptional mechanisms of activity regulation of tyrosine hydroxylase in the central nervous system – the effect of physical exercise

Numerous studies indicate that dopamine (DA) is an important regulator of motor, psychological and cognitive functions. Maintaining the appropriate concentration of DA is a condition for the proper functioning of these functions. Tyrosine hydroxylase is involved in the control of DA synthesis. The aim of this study is to discuss the regulation of TH activity with the participation of three main mechanisms: 1) post-translational immediate regulation by phosphorylation of various sites in the enzyme molecule and 2) post-transcriptional with the participation of transcription factors and specific miRNAs, and 3) a DA mediated feedback mechanism. Important factors which are directly or indirectly involved in these regulations of TH activity and DA concentration are BDNF, testosterone, alpha-synuclein and protein kinases. A drastic reduction in DA levels in the extrapyramidal system causes drastic impairment of motor, psychological and cognitive functions. On the other hand, increased physical activity, in particular prolonged repetitive physical exercises by increasing the level of testosterone and BDNF in the blood, may activate signaling pathways dependent on them, increasing the activity of tyrosine hydroxylase, and thus increase the level of dopamine in the extrapyramidal system.

Neuroprotective effects of Wharton's jelly-derived mesenchymal stem cells on motor deficits due to Parkinson's disease.

Objective(s):Human Wharton’s jelly-derived mesenchymal stem cells (hWJ-MSCs) have been recognized as a potential tool to replace damaged cells by improving the survival of the dopaminergic cells in Parkinson’s disease (PD). In this study, we examined the effects of hWJ-MSCs and associated with L-dopa/carbidopa on motor disturbances in the PD model. Materials and Methods:PD was induced by injection of 6-hydroxydopamine (6-OHDA) (16 μg/2 μl into medial forebrain bundle (MFB)). Sham group received a vehicle instead of 6-OHDA. PD+C group received hWJ-MSCs twice on the 14th and 28th days post PD induction. PD+C+D group received hWJ-MSCs and also L-dopa/carbidopa (10/30 mg/kg). PD+D group received L-dopa/carbidopa alone. Four months later, motor activities (the parameters of locomotor and muscle stiffness) were evaluated, dopaminergic neurons were counted in substantia nigra pars compacta (SNc), the level of dopamine (DA), and tyrosine hydroxylase (TH) were measured in the striatum. Results:Data indicated that motor activities, the number of dopaminergic neurons, and levels of DA and TH activities were significantly reduced in PD rats as compared to the sham group (P<0.001). However, the same parameters were improved in the treated groups when compared with the PD group (P<0.001 and P<0.01, respectively). Conclusion:The chronic treatment of PD rats with hWJ-MSCs and L-dopa/carbidopa, improved motor activity, which may be the result of increased TH activity and due to released DA from dopaminergic neurons.

Bisphenol A exposure during the embryonic period: Insights into dopamine relationship and behavioral disorders in Drosophila melanogaster

Environmental factors are involved in the pathogenesis of neurodevelopmental disorders in addition to genetic factors. In this sense, we demonstrated here that the embryonic exposure of Drosophila melanogaster to Bisphenol A (BPA) 1 mM resulted in changes in development, behavior, and biochemical markers punctuated below. BPA did not alter the oviposition and viability of the eggs, however, it was evidenced a decrease in the rate of pupal eclosion and life span of the hatched flies of the generation filial 1 (F1). F1 flies also developed behavioral changes such as incompatibility in the social interaction between them, and hyperactivity demonstrated by increased locomotion in open field tests, increased grooming, and aggression episodes. Furthermore, decreases in dopamine levels and tyrosine hydroxylase activity have also been observed in flies' heads, possibly related to oxidative damage. Through analyzes of oxidative stress biomarkers, carried out on samples of flies’ heads, we observed an increase in malondialdehyde and reactive species, decrease in the activity of the superoxide dismutase and catalase, which possibly culminated in the reduction of cell viability. Thus, it is important to emphasize that BPA developed atypical behaviors in Drosophila melanogaster, reinforce the importance of the environmental factor in the development of neurobehavioral diseases.

Catalpol Exerts Neuroprotective Effect on 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP)-Induced Mouse Model of Parkinson’s Disease and the Underlying Mechanisms

Our current study aimed to assess the preventive and therapeutic impacts of catalpol on Parkinson’s disease (PD) and its possible mechanism. In this study, mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were employed to establish a PD model and then treated with catalpol followed by analysis of behavioral science by open field test, pole-climbing assay and rotarod performance test, ROS and SOD activity and expression of TH, DAT, VEGF and GAP43 by western blot or immunofluorescence. The results disclosed that catalpol can ameliorate the MPTP-triggered loss of dopamine (DA)-producing neurons, while it was able to enhance the expression of tyrosine hydroxylase (TH), accompanied by the activation of astrocytes and microglia. Catalpol treatment significantly retarded the oxidative stress induced by MPTP, along with elevated levels of VEGF and growth-associated protein 4 (GAP43). Additionally, catalpol treatment activated the MKK4/JNK/c-Jun signal pathway in PD mouse model, accompanied by reduced secretion of pro-inflammatory factors. Catalpol executed the anti-apoptotic and anti-oxidant impacts on MPTP-induced Parkinson’s model, suggesting that it might be a novel approach for treating PD in the future.

Aerobic Exercise Activates Bdnf/creb Pathway And Enhances Behavior Features In Parkinson’S Disease Mice

Neurotrophic factors are associated with neurological disorders including Parkinson’s disease (PD). However, the role of brain-derived neurotrophic factor (BDNF) and the molecular mechanism of relative signaling mediating neuron homeostasis by exercise in PD are unclear. PURPOSE: The effect of exercise on the behavior of PD mice was analyzed, to observe the expression of neurotrophic factor of BDNF mediated by exercise, and to analyze the regulation of BDNF mediated by ERK1/2-CREB pathway. METHODS: After 8 weeks of training, the final group was as follows: Quiet + Saline group (WT), Exercise + Saline group (WE), Quiet + MPTP group (M), Exercise + MPTP group (ME). Mice in M and ME group were injected with intraperitoneal MPTP once each day for 7 times, mice in WT and WE groups received the same dose of saline intraperitoneal injection at the same time. The PD model was made, and the behavioral test was carried out, as well the molecular features were detected by immunofluorescence and Western blot. RESULTS: (1) In the behavior experiment, for step length M group decreased significantly (P < 0.05), but M group ME was significantly increased (P < 0.05) for rotation time; In open field experiment, the central activity track and total distance of WT group were higher than those of M group (P < 0.05). Although the central activity track and total distance of ME group were higher than that of M group, there was no significant difference (P > 0.05). (2) Tyrosine hydroxylase (TH) activity was detected by immunofluorescence and Western blot. Compared with WT, the expression of TH protein in M group was significantly lower (P < 0.01), while TH protein expression was increased in ME group compared with M group (P < 0.05). (3) Compared with group M, BDNF and TrkB protein expression increased after exercise training (P < 0.05). The protein expression of downstream signal marker ERK (P < 0.01), P-ERK (P < 0.01) and P-CREB (P < 0.05) were also up-regulated. CONCLUSION: Exercise training increases the neurotrophic factor BDNF expression, and activates the BDNF-CREB signaling pathway in central nervous system, in which exercise promotes the motor behavior, and alleviates the pathological features in PD mice. Key words: aerobic exercise; motor features; Tyrosine hydroxylase (TH); Neurotrophic factor BDNF; Parkinson’s disease

Glucagon-like peptide-1 receptor controls exocytosis in chromaffin cells by increasing full-fusion events.

Agonists for glucagon-like-peptide-1 receptor (GLP-1R) are currently used for the treatment of type 2 diabetes and obesity. Their benefits have been centered on pancreas and hypothalamus, but their roles in other organ systems are not well understood. We studied the action of GLP-1R on secretions of adrenal medulla. Exendin-4, a synthetic analog of GLP-1, increases the synthesis and the release of catecholamines (CAs) by increasing cyclic AMP (cAMP) production, without apparent participation of cAMP-regulated guanine nucleotide exchange factor (Epac). Exendin-4, when incubated for 24 h, increases CA synthesis by promoting the activation of tyrosine hydroxylase. Short incubation (20min) increases the quantum size of exocytotic events by switching exocytosis from partial to full fusion. Our results give a strong support to the role of GLP-1 in the fine control of exocytosis.