Tyrosine Hydroxylase Protein Expression Research Articles

Genetic Deletion of Soluble Epoxide Hydroxylase Causes Anxiety-Like Behaviors in Mice.

Soluble epoxide hydrolase (sEH), an enzyme with COOH-terminal hydrolase and NH2-terminal lipid phosphatase activities, is expressed in regions of the brain such as the cortex, white matter, hippocampus, substantia nigra, and striatum. sEH is involved in the regulation of cerebrovascular and neuronal function upon pathological insults. However, the physiological significance of sEH and its underlying mechanism in modulating brain function are not fully understood. In this study, we investigated the role of sEH in anxiety and potential underlying mechanisms in mice. Western blot for protein phosphorylation and expression was performed. Immunohistochemical analyses and Nissl and Golgi staining were performed for histological examination. Mouse behaviors were evaluated by open field activity, elevated plus maze, classical fear conditioning, social preference test, and Morris water maze. Our results demonstrated that the expression of sEH was upregulated during postnatal development in wild-type (WT) mice. Genetic deletion of sEH (sEH-/-) in mice resulted in anxiety-like behavior and disrupted social preference. Increased olfactory bulb (OB) size and altered integrity of neurites were observed in sEH-/- mice. In addition, ablation of sEH in mice decreased protein expression of tyrosine hydroxylase and reduced dopamine production in the brain. Moreover, the level of phosphorylated calmodulin kinase II (CaMKII) and glycogen synthase kinase 3 α/β (GSK3α/β) was higher in sEH-/- mice than in WT mice. Collectively, these findings suggest that sEH is a key player in neurite outgrowth of neurons, OB development in the brain, and the development of anxiety-like behavior, by regulating the CaMKII-GSK3α/β signaling pathway.

Enhanced dopamine D2 autoreceptor function in the adult prefrontal cortex contributes to dopamine hypoactivity following adolescent social stress.

Adult psychiatric disorders characterized by cognitive deficits reliant on prefrontal cortex (PFC) dopamine are promoted by teenage bullying. Similarly, male Sprague-Dawley rats exposed to social defeat in mid-adolescence (P35-39) show impaired working memory in adulthood (P56-70), along with decreased medial PFC (mPFC) dopamine activity that results in part from increased dopamine transporter-mediated clearance. Here, we determined if dopamine synthesis and D2 autoreceptor-mediated inhibition of dopamine release in the adult mPFC are also enhanced by adolescent defeat to contribute to later dopamine hypofunction. Control and previously defeated rats did not differ in either DOPA accumulation following amino acid decarboxylase inhibition (NSD-1015 100mg/kg ip.) or total/phosphorylated tyrosine hydroxylase protein expression, suggesting dopamine synthesis in the adult mPFC is not altered by adolescent defeat. However, exposure to adolescent defeat caused greater decreases in extracellular dopamine release (measured using in vivo chronoamperometry) in the adult mPFC upon local infusion of the D2 receptor agonist quinpirole (3 nM), implying greater D2 autoreceptor function. Equally enhanced D2 autoreceptor-mediated inhibition of dopamine release is seen in the adolescent (P40 or P49) mPFC, which declines in control rats by adulthood. However, this developmental decrease in autoreceptor function is absent following adolescent defeat, suggesting retention of an adolescent-like phenotype into adulthood. Current and previous findings indicate adolescent defeat decreases extracellular dopamine availability in the adult mPFC via both enhanced inhibition of dopamine release and increased dopamine clearance, which may be viable targets for improving treatment of cognitive deficits seen in neuropsychiatric disorders promoted by adolescent stress.

Neuroprotective effects of cryptotanshinone and 1,2-dihydrotanshinone I against MPTP induced mouse model of Parkinson’s disease

1,2-dihydrotanshinone I (DTs1) and cryptotanshinone (CTs) are the two major compounds isolated from Salvia castanea f. tomentosa Stib., which possess diverse biological effects such as antioxidant, anticancer, anti-​atherogenic, anti-​hepatic fibrosis. However, there is no any report available on the neuroprotective effects of DTs1 and CTs against MPTP induced dopaminergic neurons damage. Therefore, in this study, we investigated the neuroprotective effects of DTs1 and CTs in the MPTP-induced PD model of C57BL/6 mice. Locomotor behavior, tyrosine hydroxylase (TH) protein expression indicated that DTs1 and CTs significantly improved TH expression, inhibited dopaminergic cell loss induced by MPTP. Biochemical parameters determination and real-time polymerase chain reaction (PCR) analysis revealed that DTs1 and CTs increased the activities and mRNA expressions of Superoxide Dismutase (SOD), Glutathione peroxidase (GSH-Px), Catalase (CAT), deceased the level of Malondialdehyde (MDA). These findings indicated that DTs1 and CTs showed neuroprotective effects in MPTP-induced PD mice, which might be associated with their antioxidant properties.

Probiotic Kefir Antihypertensive Effects in Spontaneously Hypertensive Rats Involves Central and Peripheral Mechanisms

Gut microbiota dysbiosis has been associated with hypertension. Long‐term use of probiotics have been shown to decrease blood pressure, improve baroreflex, and ameliorate endothelial dysfunction in Spontaneously Hypertensive Rats (SHR). Yet, the mechanisms are not well understood. We aimed to evaluate peripheral and centrally mediated mechanisms by which the probiotic kefir promotes beneficial effects in SHRs. We used Wistar Kyoto (WKY) and SHR male rats, divided into: WKY and SHR treated with vehicle, and SHR treated with milk fermented by the kefir grains (5%; SHR‐Kefir; oral gavage, daily/9 weeks). We evaluated blood pressure by tail cuff method weekly. The effects of kefir were evaluated on gut anatomy (histological analysis of the small intestine), gut microbiota composition (microbiological analysis of the feces), and endotoxin levels (Lipopolysaccharide (LPS) content analyzed in serum). Within the paraventricular nucleus of the hypothalamus (PVN), we evaluated microglia activation and tyrosine hydroxylase (TH) protein expression via immunofluorescence. TH mRNA levels were analyzed via real time PCR. SHR‐Kefir presented a lower mean blood pressure (151.9±2.9mmHg) compared to SHR (173.1±2.41mmHg, P<0.0001 n=6). Basal gut microbiota composition in SHRs differed from that observed for WKY, suggesting dysbiosis. Treatment with kefir restored the normal gut microbiota composition profile of Lactobacillus, Staphylococcus, Brucella and Bifidobacterium spp. The number of Paneth cells/crypt was decreased in SHR (1.66±0.06) compared to WKY (2.40±0.08 p<0.0004), an effect which was normalized with kefir treatment (SHR‐Kefir:2.23±0.15). An increase in LPS serum content in SHR (0.71±0.02) compared to WKY (0.54±0.04 EU/mL p<0.01), suggesting increased intestinal permeability during hypertension, was reversed in SHR‐Kefir (0.54±0.01). Within the PVN, microglia density was used as an indication of microglia activation. We found increased microglia activation in SHR (9.47±0.61) compared to WKY (6.87±0.68 p<0.07), which was normalized in SHR‐Kefir rats (4.77±0.55, arbitrary units [AU]). TH protein overexpression observed in SHRs was reduced with treatment of probiotic (WKY: 5.25±0.58; SHR: 13.68±0.81 and SHR‐Kefir: 8.42±0.55, AU p<0.0001). The mRNA expression of TH within the PVN (punches) was increased in SHR by 47%. Kefir treatment decreased mRNA TH expression (WKY: 1.21±0.45; SHR: 1.79±0.50; SHR‐Kefir: 1.30±0.27 fold change). Our data shows that kefir treatment in SHRs restores gut microbiota composition and intestinal structure, diminishes levels of serum endotoxin, reduces neuroinflammation, and balances levels of tyrosine hydroxylase within the hypothalamus. Altogether, our data suggests that kefir antihypertensive‐associated mechanisms involves gut microbiota–brain axis communication during hypertension.Support or Funding InformationThis work was funded by CAPES PDSE 88881.133261/2016‐01 to MAS. VCB is funded by AHA 14SDG20400015.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The Potential Role of Toll-Like Receptor 4 in Mediating Dopaminergic Cell Loss and Alpha-Synuclein Expression in the Acute MPTP Mouse Model of Parkinson's Disease.

Toll-like receptors (TLRs) may have a role in Parkinson's disease (PD). In this study, we aimed at investigating the dopaminergic cell loss and alpha-synuclein (α-SYN) expression in TLR4-deficient mice (TLR4-/-) acutely exposed to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a pharmacological PD model. TLR4 ablation restrained the number of dopaminergic neurons in the substantia nigra (SN), as assessed by tyrosine hydroxylase (TH) protein expression. Intriguingly, TLR4-/- mice showed massive α-SYN protein accumulation in the midbrain along with high α-SYN mRNA levels in cerebral cortex, striatum, hippocampus, and cerebellum. Contrary to expectations, the high levels of α-SYN do not correlate with greater dopaminergic neuronal loss. The levels of nigral α-SYN protein in TLR4-/- mice further, but not significantly, increased during MPTP treatment. Contrariwise, MPTP treatment significantly induced the mRNA expression of α-SYN in examined brain regions of WT and TLR4-/- mice. Protein levels of GATA2, a transcription factor proposed to control α-SYN gene expression, did not change in TLR4-/- mice at baseline and after MPTP treatment. These findings suggest a role for TLR4 in mediating dopaminergic cell loss and in the constitutive expression of brain α-SYN. However, further exploration is needed in order to establish the actual role of α-SYN in the relative absence of TLR4.

Zinc as a therapy in a rat model of autism prenatally induced by valproic acid

Autism is characterized by numerous behavioral impairments, such as in communication, socialization and cognition. Recent studies have suggested that valproic acid (VPA), an anti-epileptic drug with teratogenic activity, is related to autism. In rodents, VPA exposure during pregnancy induces autistic-like effects. Exposure to VPA may alter zinc metabolism resulting in a transient deficiency of zinc. Therefore, we selected zinc as a prenatal treatment to prevent VPA-induced impairments in a rat model of autism. Wistar female rats received either saline solution or VPA (400 mg/kg, i.p) on gestational day (GD) 12.5. To test the zinc supplementation effect, after 1 h of treatment with saline or VPA, a dose of zinc (2 mg/kg, s.c.) was injected. The offspring were tested for abnormal communication behaviors with an ultrasound vocalization task on postnatal day (PND) 11, repetitive behaviors and cognitive ability with a T-maze task on PND 29, and social interaction with a play behavior task on PND 30. Tyrosine hydroxylase protein (TH) expression was evaluated in the striatum. Prenatal VPA decreased ultrasonic vocalization, induced repetitive/restricted behaviors and cognitive inflexibility, impaired socialization, and reduced striatal TH levels compared with control group. Zinc treatment reduced VPA-induced autistic-like behaviors. However, we found no evidence of an effect of zinc on the VPA-induced reduction in TH expression. The persistence of low TH expression in the VPA-Zn group suggests that Zn-induced behavioral improvement in autistic rats may not depend on TH activity.

Naringenin Decreases α-Synuclein Expression and Neuroinflammation in MPTP-Induced Parkinson's Disease Model in Mice.

The present study was designed to ascertain the role of naringenin (NGN), a citrus fruit flavanone, against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced α-synuclein (SYN) pathology and neuroinflammation in a mouse model. NGN was administered to C57BL/6J mice once a day for 5 consecutive days prior to the MPTP intoxication. On day 5, 40-50min after the NGN or vehicle administration, MPTP was injected in two divided doses (2× 40mg/kg, i.p. at 16h apart). The animals were observed for motor functions 48h after the first MPTP injection. The animals were then euthanized, the brains collected to analyze SYN pathology, cytokines, and oxidative stress levels in the substantia nigra region. The NGN significantly downregulated SYN and upregulated dopamine transporter (DAT) and tyrosine hydroxylase (TH) protein expressions. It also downregulated tumor necrosis factor-α (TNFα) and interleukin 1β (IL1β) mRNA expressions and improved superoxide dismutase levels. It also reduced glutathione levels when compared to vehicle-treated PD animals. The upregulation of TH corroborates to an increase in dopamine, DOPAC, and homovanillic acid turnover and motor functions with NGN treatment. To summarize, NGN, a dietary flavone, has the potential to counteract MPTP-induced dopaminergic degeneration by regulating SYN pathology, neuroinflammation, and oxidative stress. This warrants the investigation of NGN's potential effects in a genetic model of PD.

Role of catalpol in ameliorating the pathogenesis of experimental autoimmune encephalomyelitis by increasing the level of noradrenaline in the locus coeruleus.

The endogenous neurotransmitter, noradrenaline, exerts anti-inflammatory and neuroprotective effects in vivo and in vitro. Reduced noradrenaline levels results in increased inflammation and neuronal damage. The primary source of noradrenaline in the central nervous system is tyrosine hydroxylase (TH)-positive neurons, located in the locus coeruleus (LC). TH is the rate-limiting enzyme for noradrenaline synthesis; therefore, regulation of TH protein expression and intrinsic enzyme activity represents the central means for controlling the synthesis of noradrenaline. Catalpol is an iridoid glycoside purified from Rehmannia glutinosa Libosch, which exerts a neuroprotective effect in multiple sclerosis (MS). The present study used an experimental mouse model of autoimmune encephalomyelitis to verify the neuroprotective effects of catalpol. Significant improvements in the clinical scores were observed in catalpol-treated mice. Furthermore, catalpol increased TH expression and increased noradrenaline levels in the spinal cord. In primary cultures, catalpol exerted a neuroprotective effect in rat LC neurons by increasing the noradrenaline output. These results suggested that drugs targeting LC survival and function, including catalpol, may be able to benefit patients with MS.

Imidacloprid, a neonicotinoid insecticide, facilitates tyrosine hydroxylase transcription and phenylethanolamine N-methyltransferase mRNA expression to enhance catecholamine synthesis and its nicotine-evoked elevation in PC12D cells

Imidacloprid is a neonicotinoid insecticide acting as an agonist of nicotinic acetylcholine receptors (nAChRs) in the target insects. However, questions about the safety to mammals, including human have emerged. Overactivation of mammalian peripheral catecholaminergic systems leads to onset of tachycardia, hypertension, vomiting, etc., which have been observed in acutely imidacloprid-poisoned patients as well. Physiological activation of the nAChRs is known to drive catecholamine biosynthesis and secretion in mammalian adrenal chromaffin cells. Yet, the impacts of imidacloprid on the catecholaminergic function of the chromaffin cells remain to be evaluated. In this study using PC12D cells, a catecholaminergic cell line derived from the medulla chromaffin-cell tumors of rat adrenal gland, we examined whether imidacloprid itself could impact the catecholamine-synthesizing ability. Imidacloprid alone did facilitate tyrosine hydroxylase (TH) transcription via activation of α3β4 nAChR and the α7 subunit-comprising receptor. The insecticide showed the TH transcription-facilitating ability at the concentrations of 3 and 30 μM, at which acetylcholine is known to produce physiological responses, including catecholamine secretion through the nAChRs in adrenal chromaffin cells. The insecticide-facilitated TH transcription was also dependent on PKA- and RhoA-mediated signaling pathways. The insecticide coincidentally raised levels of TH and phenylethanolamine N-methyltransferase (PNMT) mRNA, and as a consequence, increased catecholamine production, although the efficacy of the neonicotinoid was lesser than that of nicotine, indicating its partial agonist-like action. Intriguingly, in cultured rat adrenal chromaffin cells, imidacloprid did increase levels of TH and PNMT protein. When the chromaffin cells were treated with nicotine in the presence of the insecticide, nicotine-elevated adrenaline production was enhanced due to facilitation of nicotine-increased TH and PNMT protein expression, and simultaneous enhancement of nicotine-elevated adrenaline secretion also took place. These findings thus suggest that imidacloprid may facilitate the physiological functions of adrenal glands in mammals.

Finasteride inhibited brain dopaminergic system and open-field behaviors in adolescent male rats.

Finasteride inhibits the conversion of testosterone to dihydrotestosterone. Because androgen regulates dopaminergic system in the brain, it could be hypothesized that finasteride may inhibit dopaminergic system. The present study therefore investigates the effects of finasteride in adolescent and early developmental rats on dopaminergic system, including contents of dopamine and its metabolites (dihydroxy phenyl acetic acid and homovanillic acid) and tyrosine hydroxylase expressions both at gene and protein levels. Meanwhile, open-field behaviors of the rats are examined because of the regulatory effect of dopaminergic system on the behaviors. Open-field behaviors were evaluated by exploratory and motor behaviors. Dopamine and its metabolites were assayed by liquid chromatography-mass spectrometry. Tyrosine hydroxylase mRNA and protein expressions were determined by real-time qRT-PCR and western blot, respectively. It was found that in adolescent male rats, administration of finasteride at doses of 25 and 50mg/kg for 14days dose dependently inhibited open-field behaviors, reduced contents of dopamine and its metabolites in frontal cortex, hippocampus, caudate putamen, nucleus accumbens, and down-regulated tyrosine hydroxylase mRNA and protein expressions in substantia nigra and ventral tegmental area. However, there was no significant change of these parameters in early developmental rats after finasteride treatment. These results suggest that finasteride inhibits dopaminergic system and open-field behaviors in adolescent male rats by inhibiting the conversion of testosterone to dihydrotestosterone, and imply finasteride as a potential therapeutic option for neuropsychiatric disorders associated with hyperactivities of dopaminergic system and androgen.

Nerves in the cavernous tissue of the glans penis: An immunohistochemical study using elderly donated cadavers

IntroductionThe topographical anatomy of the composite nerve fibers in the human glans penis is poorly characterized. Therefore, histological methods were used to analyze nerves to the cavernous tissue at the distal end of the corpus spongiosum. MethodsImmunohistochemical techniques were used to detect S100, neuronal nitric oxide synthase, tyrosine hydroxylase, and vasoactive intestinal polypeptide protein expressions in frontal or sagittal penile sections obtained from 20 donated, older male cadavers. ResultsAt or near the coronal sulcus at the dorsal midline, three to seven terminal branches of the unilateral dorsal nerve ran deeply or centrally along the distal dull end of the corpus cavernosum and entered the glans cavernous tissue. Once there, the nerve divided into thinner branches (neuronal nitric oxide synthase or tyrosine hydroxylase positive) and the major nerve section reached the surface skin of the glans. Several thin nerves took highly arduous paths, as evidenced in ventral subcutaneous tissue of the distal third of the penis. DiscussionHistological examination revealed a neurovascular bundle that penetrated the glans cavernous tissue toward the skin covering, with a rich nerve supply to the skin folds at and near the coronal sulcus.

The Kv7/KCNQ channel blocker XE991 protects nigral dopaminergic neurons in the 6-hydroxydopamine rat model of Parkinson’s disease

The excitability of dopaminergic neurons in the substantia nigra pars compacta (SNc) that supply the striatum with dopamine (DA) determines the function of the nigrostriatal system for motor coordination. We previously showed that 4-pyridinylmethyl-9(10H)-anthracenone (XE991), a specific blocker of Kv7/KCNQ channels, enhanced the excitability of nigral DA neurons and resulted in attenuation of haloperidol-induced catalepsy in a Parkinson’s disease (PD) rat model. However, whether XE991 exhibits neuroprotective effects towards DA neuron degeneration remains unknown. The aim of this study was to investigate the effects of Kv7/KCNQ channel blocker, XE991, on 6-hydroxydopamine (6-OHDA)-induced nigral DA neuron degeneration and motor dysfunction. Using immunofluorescence staining and western blotting, we showed that intracerebroventricular administration of XE991 prevented the 6-OHDA-induced decrease in tyrosine hydroxylase (TH)-positive neurons and TH protein expression in the SNc. High-performance liquid chromatography with electrochemical detection (HPLC-ECD) also revealed that XE991 partly restored the levels of DA and its metabolites in the striatum. Moreover, XE991 decreased apomorphine (APO)-induced contralateral rotations, enhanced balance and coordination, and attenuated muscle rigidity in 6-OHDA-treated rats. Importantly, all neuroprotective effects by XE991 were abolished by co-application of Kv7/KCNQ channel opener retigabine and XE991. Thus, Kv7/KCNQ channel inhibition by XE991 can exert neuroprotective effects against 6-OHDA-induced degeneration of the nigrostriatal DA system and motor dysfunction.

Long lasting effects of chronic WIN55,212-2 treatment on mesostriatal dopaminergic and cannabinoid systems in the rat brain

Cannabinoid administration modulates dopamine transmission via an indirect, multisynaptic mechanism that includes the activation of cannabinoid type-1 receptor (CB1R). The present study evaluated in rodents, the effects of acute and chronic (20 days) WIN55,212-2 administration, a non-selective CB1R agonist, on dopamine uptake and synthesis in the mesolimbic and nigrostriatal dopaminergic pathways and associate them to its effects on the endocannabinoid system. The effect of spontaneous withdrawal, after different abstinence periods (7 days, 20 days), was also assessed. Acute and chronic administration of WIN55,212-2 decreased dopamine transporter (DAT) binding and mRNA levels, as well as tyrosine hydroxylase (TH) mRNA expression in the substantia nigra (SN) and ventral tegmental area (VTA). In the striatum, chronic WIN55,212-2 administration led to decreased protein expression of DAT and TH, whereas no alterations were observed after acute administration, suggesting a diminished dopamine uptake and synthesis after chronic agonist treatment. Furthermore, after chronic agonist treatment, we observed reduced CB1R binding and mRNA levels in SN and striatum, providing evidence for a possible regulatory role of the endocannabinoid system on dopaminergic function. Seven days after WIN55,212-2 cessation, we observed a rebound increase in mRNA, binding and total protein levels of DAT and TH in VTA, SN and striatum proposing the existence of a biphasic expression pattern, which was also observed in CB1R binding levels. Within the 20-day period of abstinence, TH mRNA and protein levels and CB1R binding levels remain increased. The above results indicate that chronic CB1R agonist treatment induces long-lasting control of the mesostriatal dopaminergic activity.

Effect of Wnt1 and Wnt5a on the development of dopaminergic neurons, and toxicity induced by combined exposure to paraquat and maneb during gestation and lactation.

Paraquat (PQ) and maneb (MB) are widely used herbicides. Wingless (Wnt) proteins serve a role in the development and differentiation of dopaminergic neurons. Previous studies demonstrated that combined exposure to PQ and MB damages dopaminergic neurons in the midbrain. Effects of PQ and MB exposure on midbrain Wnt proteins have also been previously reported. In the present study, from the 5th day of gestation to weaning of the offspring, pregnant Sprague‑Dawley rats were administrated saline, or PQ and MB at two different doses: high, 15mg/kg body weight PQ+45mg/kg body weight MB; or low, 10mg/kg body weight PQ+30mg/kg body weight MB. Dopamine content in the striatum was examined by high performance liquid chromatography with a fluorescence detector and mRNA and protein expression of Wnt1, Wnt5a, nuclear receptor related factor 1 (Nurr1) and tyrosine hydroxylase (TH) in the midbrain was examined by reverse transcription‑quantitative polymerase chain reaction and western blotting. Combined exposure to PQ and MB during development decreased mRNA and protein expression of Wnt1, TH and Nurr1 and increased expression of Wnt5a in the offspring.

P.1.a.006 - Association of dopamine transporter gene SLC6A3 polymorphisms with remission and antidepressant therapy response in patients with depressive disorders

Prenatal stress (PNS) has its negative impact on both the infant hippocampal neurogenesis and pregnancy outcomes in the neonates that serves as a risk factor for postnatal depression in adult offsprings. Therefore, main objectives of the present study were to evaluate the effect of maternal chronic unpredictable mild stress (CUMS) on behavioural changes, levels of oxidative stress, changes in selective developmental signaling genes and neurogenesis in the adult brain of Wistar rats and its reversal through a selective non-ergoline D2 type dopamine receptor (D2R) agonist Ropinirole (ROPI). Effects of ROPI treatment on CUMS induced adult rats offspring were measured by assessment of behavioural tests (sucrose preference test and forced swim test), biomarkers of oxidative stress, protein expression of tyrosine hydroxylase (TH), mRNA expression of SHH, GSK-3β, β-catenin, Notch, brain-derived neurotrophic factor (BDNF), Dopamine receptor 2 (Drd2) and bromodeoxyuridine (BrdU) cell proliferation assay. The oxidative stress, protein and mRNA expression were determined in the hippocampus and prefrontal cortex while the BrdU cell proliferation was observed in the hippocampus of rat brain. PNS induced changes resulted in depression validated by the depression-like behaviours, increased oxidative stress, decreased TH expression, altered expression of selective developmental genes, along with the reduced hippocampal neurogenesis and BDNF expression in the brain of adult offsprings. Chronic ROPI treatment reversed those effects and was equally effective like Imipramine (IMI) treatment. So, the present study suggested that ROPI can be used as an antidepressant drug for the treatment of depressive disorders.

The Non-Survival Effects of Glial Cell Line-Derived Neurotrophic Factor on Neural Cells.

Glial cell line-derived neurotrophic factor (GDNF) was first characterized as a survival-promoting molecule for dopaminergic neurons (DANs). Afterwards, other cells were also discovered to respond to GDNF not only as a survival factor but also as a protein supporting other cellular functions, such as proliferation, differentiation, maturation, neurite outgrowth and other phenomena that have been less studied than survival and are now more extendedly described here in this review article. During development, GDNF favors the commitment of neural precursors towards dopaminergic, motor, enteric and adrenal neurons; in addition, it enhances the axonal growth of some of these neurons. GDNF also induces the acquisition of a dopaminergic phenotype by increasing the expression of Tyrosine Hydroxylase (TH), Nurr1 and other proteins that confer this identity and promote further dendritic and electrical maturation. In motor neurons (MNs), GDNF not only promotes proliferation and maturation but also participates in regenerating damaged axons and modulates the neuromuscular junction (NMJ) at both presynaptic and postsynaptic levels. Moreover, GDNF modulates the rate of neuroblastoma (NB) and glioblastoma cancer cell proliferation. Additionally, the presence or absence of GDNF has been correlated with conditions such as depression, pain, muscular soreness, etc. Although, the precise role of GDNF is unknown, it extends beyond a survival effect. The understanding of the complete range of properties of this trophic molecule will allow us to investigate its broad mechanisms of action to accelerate and/or improve therapies for the aforementioned pathological conditions.

Substantial protection against MPTP-associated Parkinson's neurotoxicity in vitro and in vivo by anti-cancer agent SU4312 via activation of MEF2D and inhibition of MAO-B

We have previously demonstrated the unexpected neuroprotection of the anti-cancer agent SU4312 in cellular models associated with Parkinson's disease (PD). However, the precise mechanisms underlying its neuroprotection are still unknown, and the effects of SU4312 on rodent models of PD have not been characterized. In the current study, we found that the protection of SU4312 against 1-methyl-4-phenylpyridinium ion (MPP+)-induced neurotoxicity in PC12 cells was achieved through the activation of transcription factor myocyte enhancer factor 2D (MEF2D), as evidenced by the fact that SU4312 stimulated myocyte enhancer factor 2 (MEF2) transcriptional activity and prevented the inhibition of MEF2D protein expression caused by MPP+, and that short hairpin RNA (ShRNA)-mediated knockdown of MEF2D significantly abolished the neuroprotection of SU4312. Additionally, Western blotting analysis revealed that SU4312 potentiated pro-survival PI3-K/Akt pathway to down-regulate MEF2D inhibitor glycogen synthase kinase-3beta (GSK3β). Furthermore, using the in vivo PD model of C57BL/6 mice insulted with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we found that intragastrical administration of SU4312 (0.2 and 1 mg/kg) greatly ameliorated Parkinsonian motor defects, and restored protein levels of MEF2D, phosphorylated-Ser473-Akt and phosphorylated-Ser9-GSK3β. Meanwhile, SU4312 effectively reversed the decrease in protein expression of tyrosine hydroxylase in substantia nigra pars compacta dopaminergic neurons, inhibited oxidative stress, maintained mitochondrial biogenesis and partially prevented the depletion of dopamine and its metabolites. Very encouragingly, SU4312 was able to selectively inhibit monoamine oxidase-B (MAO-B) activity both in vitro and in vivo, with an IC50 value of 0.2 μM. These findings suggest that SU4312 provides therapeutic benefits in cellular and animal models of PD, possibly through multiple mechanisms including enhancement of MEF2D through the activation of PI3-K/Akt pathway, maintenance of mitochondrial biogenesis and inhibition of MAO-B activity. SU4312 thus may be an effective drug candidate for the prevention or even modification of the pathological processes of PD.

Glabridin attenuates MPTP-induced parkinson disease by inhibiting extracellular regulated protein kinases signaling pathway

Objective: To investigate whether Glabridin had a beneficial effect on 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine(MPTP) induced parkinson disease (PD) in mice, and explore the possible underlying mechanisms. Methods: Forty C57BL/6N mice were randomly assigned into control group, MPTP group, Glabridin therapy(MPTP+ GLA)group, Levodopa therapy(MPTP+ LD)group, with 10 in each group. PD model was induced by intraperitoneal administration of MPTP(20 mg/kg). The mice in MPTP+ GLA group, MPTP+ LD group and control group were gavaged by glabridin (50 mg/kg), levodopa (40 mg/kg), and equal volume of normal saline, respectively. The behavioral changes of each group were observed and Y-type electric maze test was performed. The levels of tumor necrosis factor-α (TNF-α) and interleukin-18 (IL-18) were assayed by enzyme-linked immunosorbent assay (ELISA). Malondialdehyde (MDA), and superoxide dismutase (SOD) were analyzed. The protein expression of tyrosine hydroxylase (TH) and extracellular signal regulated protein kinase (ERK) protein expression of hippocampus tissue was detected using immunohistochemical techniques. TH and pERK protein expression of hippocampus tissue were detected by Western blotting. Results: Mice in MPTP group showed typical behavior of PD, and the ability of learning and memory was significantly lower than those in the control group. Compared with MPTP group, the expressions of TNF-α and IL-18 were suppressed by GLA in hippocampus[TNF-α(μg/L): 84.04±18.66 vs 106.53±28.54; IL-18(μg/L): 42.34±6.01 vs 58.42±8.39]. The levels of MDA in hippocampus were down-regulated significantly in groups administrated with GLA[MDA(nmol/mgprot): 2.64±0.52vs 3.78±0.31], while the SOD level increased after GLA administration[SOD(U/mgprot): 93.45±9.59 vs 77.83±8.98]. The results of immunohistochemistry showed the expression of TH protein in MPTP group was significantly decreased compared with that in control group, while the p-ERK protein in MPTP group was significantly increased. In MPTP+ GLA group and MPTP+ LD group, the expression of TH protein was significantly higher than that in MPTP group, and the expression of p-ERK protein was significantly lower than that in MPTP group. Western blot results showed that compared with control group, the expression of TH was significantly decreased, and p-ERK protein in hippocampus was significantly higherin MPTP group. The expression of TH protein was significantly higher in MPTP+ GLA group than that in MPTP group, while the expression of p-ERK protein were inhibited by GLA in MPTP-induced PD mice. Conclusion: Traditional Chinese medicine glabridin can protect the learning and memory ability of PD mice induced by MPTP by inhibition of the ERK signal pathway, antioxidation and reduction of inflammation.

Immediate-early c-fos and tyrosine hydroxylase protein expression in different brain regions in high-fat induced obesity in mice

To examine brain dopamine expression in chronic high-fat diet(HFD)-induced obese mice. Ten male mice were fed by a high-fat diet (HF:45% of calories from fat) for 12 weeks and then classified as HFD group. Ten male mice were fed a low-fat diet (LF:10% of calories from fat) and used as control group (NCD). In the 10th week, the blood of the caudal vein was collected to determine the basal blood glucose level after both groups mice were fast for 12 h. Intraperitoneal (IP) glucose tolerance test (GTT) and insulin tolerance (ITT) were performed in HFD and NCD mice in the 12th week. Animals were sacrificed after fasting for 4 hours at the 12th week. Brain tissues were processed for Fos-ir and TH-ir by immunohistochemistry. After 12 weeks of feeding, body weight was significant higher in HFD mice than that in NCD ones. During GTT and ITT, HFD mice had significantly decreased glucose tolerance and insulin tolerance at 15 min and 30 min respectively than NCD ones (P<0.05). There were higher plasma insulin concentration and leptin concentration in HFD mice than those in NCD ones (P<0.05). High fat-induced increased body weight was associated with increased cellular activation, indicated by Fos immunoreactive (ir) staining, in nucleus accumbens(NAcc), paraventricular nucleus (PVN), ventral tegmental area (VTA) and substantia nigra (SN) than those of NCD ones (P<0.05); and also significantly associated with enhanced in the number of cells labeled for tyrosine hydroxylase (TH-ir), and the number of cells co-labeled for TH-ir/Fos-ir in the VTA and SN than those of NCD ones (P<0.01). Moreover, there was significantly relationship TH-ir positive cell numbers with final body weight in VTA and SN in HFD mice (P<0.05). The results showed that chronic consumption of high-fat food was associated with plasticity-related changes in reward circuitry in mice.

Chronic obstructive sleep apnea promotes aortic remodeling in canines through miR-145/Smad3 signaling pathway.

Obstructive sleep apnea (OSA) is a causal pathogenetic factor of many cardiovascular diseases, however, its role in aortic diseases remains unknown. Therefore, this study was performed to explore the potential effects and pathophysiological mechanisms of chronic OSA on aortic remodeling in a canine model. After chronic OSA, the morphological changes of ascending aorta were characterized by thinner cells with pycnotic nuclei and swollen mitochondria, and obvious hyperplasia of collagenous fiber in the matrix. Both the apoptotic ratio and collagen volume fraction were significantly increased in ascending aorta of chronic OSA canines. Besides, aortic sympathetic nerve sprouting increased significantly in chronic OSA group. Meanwhile, protein expression of TGF-β1, Smad3, collagenI, apoptosis-inducing factor (AIF), tyrosine hydroxylase (TH) and growth associated protein-43 (GAP43) was upregulated after chronic OSA. Additionally, chronic OSA also strikingly increased pro-inflammatory factors like tumor necrosis factor α (TNF-α), NOD-like receptor 3 (NLRP3), NF-κB-p65 and oxidative stress factors like xanthine oxidase (XOD), malondialdehyde (MDA) while declined superoxide dismutase (SOD) activity. Furthermore, suppressed miR-145 and subsequently increased Smad3 expression were found obviously in vascular smooth muscle cells (VSMCs) treated by hypoxia. Luciferase reporter assays confirmed that Smad3 was one of the targets of miR-145. In conclusion, OSA could exacerbate aortic remodeling by aortic fibrosis, apoptosis and sympathetic nerve sprouting. miR-145/Smad3 signaling pathway might promote aortic remodeling during OSA. These findings provide novel information of chronic OSA-induced vascular dysfunction.