(-)-Epigallocatechin-3-gallate promotes intestinal epithelial proliferation and barrier function after ischemia/reperfusion injury via activation of Nurr1.

CONTEXT: (-)-Epigallocatechin-3-gallate (EGCG) is involved in cell proliferation and ischemia/reperfusion (I/R) injury of several organs. OBJECTIVE: To identify the role of EGCG in intestinal epithelial proliferation and barrier exposed to I/R injury. MATERIAL AND METHODS: Fifty Sprague-Dawley rats were divided into sham, I/R, I/R + EGCG (12.5 mg/kg), I/R + EGCG (25 mg/kg) and I/R + EGCG (50 mg/kg). I/R group rats were subjected to intestinal ischemia for 1 h and 6 h reperfusion. The rats were supplemented with EGCG 12.5, 25 and 50 mg/kg daily for 3 days via intraperitoneal injection before surgery. We used IEC-6 to expose to hypoxia/reoxygenation (H/R) injury to mimic I/R in vivo. IEC-6 cells were divided into control, H/R and H/R + EGCG (40 µmol/L). The effects of EGCG and its mechanism was explored. RESULTS: Pharmacological treatment with EGCG notably improves intestinal epithelial proliferation (12.5 mg/kg, 1.74-fold; 25 mg/kg, 2.93-fold, and 50 mg/kg, 4.33-fold) and barrier function after I/R injury. EGCG promoted cell proliferation (2.99-fold) and increased the expression of occludin (2.36-fold) and ZO-1 (1.64-fold) in IEC-6 cells after H/R injury. EGCG promoted proliferation of IEC-6 cells with ED50 values of 18.16 µmol/L. Further investigations indicated that EGCG activated Nurr1 expression in intestine after I/R injury. EGCG promote cell proliferation and increased the expression of occludin and ZO-1 in IEC-6 cells after H/R injury were abrogated in the knockdown of Nurr1 by siRNA. DISCUSSION AND CONCLUSION: Our findings indicate that EGCG promotes intestinal epithelial cell proliferation and barrier function after I/R injury in vitro and in vivo via activation of Nurr1.

Structural, molecular hybridization and network based identification of miR-373-3p and miR-520e-3p as regulators of NR4A2 human gene involved in neurodegeneration.

MicroRNAs (miRNAs) are short non-coding RNAs with a 22 nucleotide sequence length and docks to the 3'UTR/5'UTR of the gene to regulate their mRNA translation to play a vital role in neurodegenerative diseases. The Nuclear Receptor gene (NR4A2), a transcription factor, and a steroid-thyroid hormone retinoid receptor is involved in neural development, memory formation, dopaminergic neurotransmission, and cellular protection from inflammatory damage. Therefore, recognizing the miRNAs is essential to efficiently target the 3'UTR/5'UTR of the NR4A2 gene and regulate neurodegeneration. Highly stabilized top miRNA-mRNA hybridized structures, their homologs, and identification of the best structures based on their least free energy were evaluated using in silico techniques. The miR-gene, gene-gene network analysis, miR-disease association, and transcription factor binding sites were also investigated. Results suggest top 166 miRNAs targeting the NR4A2 mRNA, but with a total of 10 miRNAs bindings with 100% seed sequence identity (both at 3' and 5'UTR) at the same position on the NR4A2 mRNA region. The miR-373-3p and miR-520e-3p are considered the best candidate miRNAs hybridizing with high efficiency at both 3' and 5'UTR of NR4A2 mRNA. This could be due to the most significant seed sequence length complementary, supplementary pairing, and absence of non-canonical base pairs. Furthermore, the miR-gene network, target gene-gene interaction analysis, and miR-disease association provide an understanding of the molecular, cellular, and biological processes involved in various pathways regulated by four transcription factors (PPARG, ZNF740, NRF1, and RREB1). Therefore, miR-373-3p, 520e-3p, and four transcription factors can regulate the NR4A2 gene involved in the neurodegenerative process.

High lithium levels in tobacco may account for reduced incidences of both Parkinson's disease and melanoma in smokers through enhanced ß-catenin-mediated activity.

Parkinson's disease (PD) patients have higher rates of melanoma and vice versa, observations suggesting that the two conditions may share common pathogenic pathways. ß-Catenin is a transcriptional cofactor that, when concentrated in the nucleus, upregulates the expression of canonical Wnt target genes, such as Nurr1, many of which are important for neuronal survival. ß-Catenin-mediated activity is decreased in sporadic PD as well as in leucine-rich repeat kinase 2 (LRRK2) and ß-glucosidase (GBA) mutation cellular models of PD, which is the most common genetic cause of and risk for PD, respectively. In addition, ß-catenin expression is significantly decreased in more aggressive and metastatic melanoma. Multiple observational studies have shown smokers to have significantly lower rates of PD as well as melanoma implying that tobacco may contain one or more elements that protect against both conditions. In support, smoker's brains have significantly reduced levels of α-synuclein, a pathological intracellular protein found in PD brain and melanoma cells. Tobacco contains very high lithium levels compared to other plants. Lithium has a broad array of neuroprotective actions, including enhancing autophagy and reducing intracellular α-synuclein levels, and is effective in both neurotoxin and transgenic preclinical PD models. One of lithium's neuroprotective actions is enhancement of ß-catenin-mediated activity leading to increased Nurr1 expression through its ability to inhibit glycogen synthase kinase-3 ß (GSK-3ß). Lithium also has anti-proliferative effects on melanoma cells and the clinical use of lithium is associated with a reduced incidence of melanoma as well as reduced melanoma-associated mortality. This is the first known report hypothesizing that inhaled lithium from smoking may account for the associated reduced rates of both PD and melanoma and that this protection may be mediated, in part, through lithium-induced GSK-3ß inhibition and consequent enhanced ß-catenin-mediated activity. This hypothesis could be directly tested in clinical trials assessing lithium therapy's ability to affect ß-catenin-mediated activity and slow disease progression in patients with PD or melanoma.

Proliferation and committed differentiation into dopamine neurons of neural stem cells induced by the active ingredients of radix astragali.

Neural stem cells (NSCs) are important cellular sources of transplantation therapies for Parkinson's disease. This study aimed to determine the effects of extracts of radix astragali on the proliferation and differentiation into dopamine (DA) neurons in NSCs. NSCs were dealt with astragaloside IV (ASI), astragalus polysaccharide (APS), and astraisoflavan (ASF), the main active ingredients of radix astragali. First, the results from cell-count kit-8 (CCK-8) assay showed that ASI, ASF, and APS had positive effects on the proliferation of NSCs. Next, we also confirmed the effects of ASI, APS, and ASF on BrdU and nestin by immunocytochemistry. Moreover, results from quantitative RT-PCR showed ASI, APS, and ASF could promote the expressions of tyrosine hydroxylase and dopamine transporter mRNA, which are specifically expressed in DA neurons. Simultaneously, sonic hedgehog (Shh), orphan nuclear hormone 1 (Nurr1), and pituitary homeobox 3 (Ptx3) are considered to motivate the formation of DA neurons. Our result showed ASI, APS, and ASF can also promote the expressions of Shh, Nurr1, and Ptx3 mRNAs. In conclusion, our study verifies that the active ingredients of radix astragali can promote the proliferation of NSCs and induce NSC differentiation toward DA neurons in vitro. These phenomena may occur through upregulation of Shh, Nurr1, and Ptx3 in the process of drug treatment.

Anti­inflammatory effect of Migri­Heal® in an in vitro inflammatory model of primary mixed glial cells.

Migri­Heal®, is a novel herbal remedy that was introduced for the treatment of migraine headaches. Previous studies revealed that this drug may reduce nitric oxide (NO) in an in vitro inflammatory model. The aim of the present study was to investigate the anti­inflammatory effect of Migri­Heal® on primary mix glial cells stimulated with LPS. In the current study, neonatal rat primary mix glial cells were isolated from the mixed glial cultures via shaking, and cultured in Dulbecco's' modified Eagle's medium supplemented with 10% fetal bovine serum. Following pretreatment with Migri­Heal® (25, 75, 100, 150, 200 and 300 µg/ml) and cells were treated with LPS (10 µg/ml) for 1 h, and incubated for 48 h. The present study determined that 150 µg/ml Migri­Heal® significantly reduced the production of NO in rat mix glial cells stimulated with 10 µg/ml LPS. Migri­Heal® also suppressed mRNA expression level of LPS­induced inducible nitric oxide synthase and tumor necrosis factor α, which was accompanied by inhibition of the transcription factor nuclear factor­κB. Additionally, MTT assay determined that Migri­Heal® was not cytotoxic, suggesting that the anti­inflammatory effects of Migri­Heal® observed were not due to cell death. In conclusion, the findings of the present study demonstrated that Migri­Heal® may be useful as a potential anti­inflammatory agent in inflammatory diseases. However, additional studies are required to confirm these findings.

Daphnane and Phorbol Diterpenes, Anti-neuroinflammatory Compounds with Nurr1 Activation from the Roots and Stems of Daphne genkwa.

The methanol extract of the roots and stems of Daphne genkwa and its constituents yuanhuacin (1) and genkwanine N were previously reported to have Nurr1 activating effects and neuroprotective effects in an animal model of Parkinson's disease (PD). In this study, four more daphnane-type diterpenes (acutilonine F (2), wikstroemia factor M1 (3), yuanhuadine (5), and yuanhuatine (6)) and two phorbol-type diterpenes (prostratin Q (4) and 12-O-n-deca-2,4,6-trienoyl-phorbol-(13)-acetate (7)) were isolated as Nurr1 activating compounds from the D. genkwa extract. Consistent with their higher Nurr1 activating activity, compounds 1, 4, 5, and 7 exhibited higher inhibitory activity on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in murine microglial BV-2 cells with an IC50 (µM) of 1-2, which was 15-30 times more potent than that of minocycline (29.9 µM), a well-known anti-neuroinflammatory agent. Additionally, these diterpenes reduced expression and transcription of LPS-induced pro-inflammatory cytokines in BV-2 cells. Thus, the daphnane-type and phorbol-type diterpenes had anti-neuroinflammatory activity with Nurr1 activation and could be responsible for the anti-PD effect of the roots and stems of D. genkwa.

cDNA microarray analysis identifies NR4A2 as a novel molecule involved in the pathogenesis of Sjögren's syndrome.

To examine genes expressed specifically in labial salivary glands (LSGs) of patients with Sjögren's syndrome (SS) in comparison with those of patients with immunoglobulin (Ig)G4-related disease (IgG4-RD), and to identify the genes involved in the pathogenesis of SS. Gene expression in LSGs of SS patients, IgG4-RD patients and healthy controls (HC) was analysed by cDNA microarray. Quantitative polymerase chain reaction (qPCR) was used to validate the up-regulation of differentially expressed genes (DEGs) in SS. Protein production of the validated gene in LSGs was examined by immunofluorescence (IF) assay. The association of molecular functions of the gene with the pathological conditions in SS was examined using peripheral blood lymphocytes. Among 1320 DEGs up-regulated in SS, qPCR confirmed the up-regulation of NR4A2 in LSGs of SS compared with IgG4-RD. IF staining showed higher production of NR4A2 in nuclei of CD4+ T cells and interleukin (IL)-17-producing cells in LSGs of SS, compared with IgG4-RD. Over-expression of NR4A2 mRNA was observed in peripheral CD4+ T cells of SS patients, compared with HC. Nuclear NR4A2 expression in T helper type 17 (Th17)-polarized CD4+ T cells determined by cellular IF was significantly higher in SS than in HC. Importazole, an inhibitor of importin-ß, inhibited nuclear transport of NR4A2 and Th17 polarization along with IL-21 expression in naive CD4+ T cells under Th17-polarizing conditions, but did not alter retinoic acid receptor-related orphan receptor C (RORC) expression. NR4A2 seems to promote Th17 polarization via increased expression and intranuclear localization in CD4+ T cells of SS patients, which could play a critical role in the pathogenesis of SS.

Protective effects of a herbal extract combination of Bupleurum falcatum, Paeonia suffruticosa, and Angelica dahurica against MPTP-induced neurotoxicity via regulation of nuclear receptor-related 1 protein.

Parkinson's disease (PD) is one of the progressive neurodegenerative diseases of whose condition is characterized by dopaminergic neuronal cell loss and dysfunction in the substantia nigra pars compacta (SNpc) and the striatum. Recent studies have demonstrated that the nuclear receptor-related 1 protein (Nurr1) is critical of dopaminergic phenotype induction in mesencephalic dopaminergic neurons. Further, Nurr1 engages in synthesizing and storing dopamine through regulating levels of tyrosine hydroxylase (TH), dopamine transporter (DAT) and vesicular monoamine transporter 2 (VMAT2). The aim of this study was to investigate the protective effects of a herbal extract combination, consisting of Bupleurum falcatum, Paeonia suffruticosa, and Angelica dahurica (MABH), on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD-like symptoms and to elucidate possible mechanisms of action focusing on Nurr1. In a subacute mouse model of MPTP-induced PD, MABH treatment resulted in recovery from movement impairments. MABH prevented dopamine depletion and protected against dopaminergic neuronal degradation induced by MPTP. Additionally, MABH increased Nurr1 expression in the SNpc of mice. To evaluate the effects of MABH on Nurr1 expression, we measured the protein levels of Nurr1 and its regulating factors using Western blot analysis in PC12 cells. MABH treatment induced the phosphorylation of extracellular signal-regulated kinase protein via increasing the protein expression levels of Nurr1 and ultimately the levels of TH, VMAT2, and DAT. These results indicate that MABH has protective effects on dopaminergic neurons in a mouse model of PD by regulating Nurr1.

Active coping of prenatally stressed rats in the forced swimming test: involvement of the Nurr1 gene.

Depending on genetic predisposition, prenatal stress may result in vulnerability or resilience to develop psychiatric disorders in adulthood. Nurr1 is an immediate early gene, important in the brain for the stress response. We tested the hypothesis that prenatal stress and the decrease of hippocampal Nurr1 alter offspring behavioral responses in the forced swimming test (FST). Pregnant Wistar rats were exposed to restraint stress (45 min, thrice daily) from gestation day 14. Prenatally stressed (PS) and non-prenatally stressed (NPS) male offspring were treated bilaterally with a Nurr1 antisense oligodeoxynucleotide (ODN; or control) into the hippocampus at 97 d of age. After 1 h, the rats were exposed to the FST (acute stressor) to analyze their behavioral responses. Thirty minutes after the FST, we analyzed the gene expression of Nurr1, Bdnf and Nr3c1 (genes for Nurr1, brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor (GR), respectively) in the hippocampus, prefrontal cortex (PFC) and hypothalamus. Results showed that the decrease of hippocampal Nurr1 after the antisense ODN in adult NPS rats induces immobility (indicating depressive-like behavior). The PS adult rats, including the group with decreased hippocampal Nurr1, presented low immobility in the FST. This low immobility was concordant with maintenance of Nurr1 and Bdnf expression levels in the three analyzed brain regions; Nr3c1 gene expression was also maintained in the PFC and hypothalamus. These findings suggest that Nurr1 and associated genes could participate in the brain modifications induced by prenatal stress, allowing active coping (resilience) with acute stress in adulthood.

Nurr1-Based Therapies for Parkinson's Disease.

Previous studies have documented that orphan nuclear receptor Nurr1 (also known as NR4A2) plays important roles in the midbrain dopamine (DA) neuron development, differentiation, and survival. Furthermore, it has been reported that the defects in Nurr1 are associated with Parkinson's disease (PD). Thus, Nurr1 might be a potential therapeutic target for PD. Emerging evidence from in vitro and in vivo studies has recently demonstrated that Nurr1-activating compounds and Nurr1 gene therapy are able not only to enhance DA neurotransmission but also to protect DA neurons from cell injury induced by environmental toxin or microglia-mediated neuroinflammation. Moreover, modulators that interact with Nurr1 or regulate its function, such as retinoid X receptor, cyclic AMP-responsive element-binding protein, glial cell line-derived neurotrophic factor, and Wnt/ß-catenin pathway, have the potential to enhance the effects of Nurr1-based therapies in PD. This review highlights the recent progress in preclinical studies of Nurr1-based therapies and discusses the outlook of this emerging therapy as a promising new generation of PD medication.

The HDAC inhibitor SAHA improves depressive-like behavior of CRTC1-deficient mice: Possible relevance for treatment-resistant depression.

Major depression is a highly complex disabling psychiatric disorder affecting millions of people worldwide. Despite the availability of several classes of antidepressants, a substantial percentage of patients are unresponsive to these medications. A better understanding of the neurobiology of depression and the mechanisms underlying antidepressant response is thus critically needed. We previously reported that mice lacking CREB-regulated transcription coactivator 1 (CRTC1) exhibit a depressive-like phenotype and a blunted antidepressant response to the selective serotonin reuptake inhibitor fluoxetine. In this study, we similarly show that Crtc1(-/-) mice are resistant to the antidepressant effect of chronic desipramine in a behavioral despair paradigm. Supporting the blunted response to this tricyclic antidepressant, we found that desipramine does not significantly increase the expression of Bdnf and Nr4a1-3 in the hippocampus and prefrontal cortex of Crtc1(-/-) mice. Epigenetic regulation of neuroplasticity gene expression has been associated with depression and antidepressant response, and histone deacetylase (HDAC) inhibitors have been shown to have antidepressant-like properties. Here, we show that unlike conventional antidepressants, chronic systemic administration of the HDAC inhibitor SAHA partially rescues the depressive-like behavior of Crtc1(-/-) mice. This behavioral effect is accompanied by an increased expression of Bdnf, but not Nr4a1-3, in the prefrontal cortex of these mice, suggesting that this epigenetic intervention restores the expression of a subset of genes by acting downstream of CRTC1. These findings suggest that CRTC1 alterations may be associated with treatment-resistant depression, and support the interesting possibility that targeting HDACs may be a useful therapeutic strategy in antidepressant development.

Nuclear receptor 4A (NR4A) family - orphans no more.

The orphan nuclear receptors NR4A1, NR4A2 and NR4A3 are immediate early genes induced by multiple stressors, and the NR4A receptors play an important role in maintaining cellular homeostasis and disease. There is increasing evidence for the role of these receptors in metabolic, cardiovascular and neurological functions and also in inflammation and inflammatory diseases and in immune functions and cancer. Despite the similarities of NR4A1, NR4A2 and NR4A3 and their interactions with common cis-genomic elements, they exhibit unique activities and cell-/tissue-specific functions. Although endogenous ligands for NR4A receptors have not been identified, there is increasing evidence that structurally-diverse synthetic molecules can directly interact with the ligand binding domain of NR4A1 and act as agonists or antagonists, and ligands for NR4A2 and NR4A3 have also been identified. Since NR4A receptors are key factors in multiple diseases, there are opportunities for the future development of NR4A ligands for clinical applications in treating multiple health problems including metabolic, neurologic and cardiovascular diseases, other inflammatory conditions, and cancer.

Shikonin, a constituent of Lithospermum erythrorhizon exhibits anti-allergic effects by suppressing orphan nuclear receptor Nr4a family gene expression as a new prototype of calcineurin inhibitors in mast cells.

Over the last few decades, food allergy (FA) has become a common disease in infants in advanced countries. However, anti-allergic medicines available in the market have no effect on FA, and consequently effective drug therapies for FA are not yet available. We have already demonstrated that mucosal mast cells play an essential role in the development of FA in a murine model. Thus, we screened many constituents from medicinal herbs for the ability to inhibit rat basophilic leukemia-2H3 mast-like cell degranulation, and found that shikonin, a naphthoquinone dye from Lithospermum erythrorhizon, exhibited the most potent inhibitory effect among them. Furthermore, shikonin extremely inhibited the IgE/antigen-induced and calcium ionophore-induced upregulation of tumor necrosis factor (TNF)-α mRNA expression in mucosal-type bone marrow-derived mast cells (mBMMCs). Global gene expression analysis confirmed by real-time PCR revealed that shikonin drastically inhibited the IgE/antigen-induced and calcium ionophore-induced upregulation of mRNA expression of the nuclear orphan receptor 4a family (Nr4a1, Nr4a2 and Nr4a3) in mBMMCs, and knockdown of Nr4a1 or Nr4a2 suppressed the IgE/antigen-induced upregulation of TNF-α mRNA expression. Computational docking simulation of a small molecule for a target protein is a useful technique to elucidate the molecular mechanisms underlying the effects of drugs. Therefore, the simulation revealed that the predicted binding sites of shikonin to immunophilins (cyclophilin A and FK506 binding protein (FKBP) 12) were almost the same as the binding sites of immunosuppressants (cyclosporin A and FK506) to immunophilins. Indeed, shikonin inhibited the calcineurin activity to a similar extent as cyclosporin A that markedly suppressed the IgE/antigen-enhanced mRNA expression of TNF-α and the Nr4a family in mBMMCs. These findings suggest that shikonin suppresses mucosal mast cell activation by reducing Nr4a family gene expression through the inhibition of calcineurin activity. Therefore, shikonin has therapeutic potential for the treatment of allergic diseases as a new calcineurin inhibitor.

Nuclear orphan receptor NR4A2 confers chemoresistance and predicts unfavorable prognosis of colorectal carcinoma patients who received postoperative chemotherapy.

BACKGROUND: NR4A2, an orphan nuclear receptor essential in neuron generation, has been recently linked to inflammatory and metabolic pathways of colorectal carcinoma (CRC). However, the effects of NR4A2 on chemo-resistance and postoperative prognosis of CRC remain unknown. METHODS: NR4A2 was transfected into CRC cells to investigate its effects on chemo-resistance to 5-fluorouracil and oxaliplatin and chemotherapeutics-induced apoptosis. We also investigated prostaglandin E2 (PGE2)-induced NR4A2 expression and its effect on chemo-resistance. Tissue microarrays including 51 adenoma, 14 familial adenomatous polyposis with CRC, 17 stage IV CRC with adjacent mucosa and 682 stage I-III CRC specimens were examined immunohistochemically for NR4A2 expression. Median follow-up time for stage I-III CRC patients was 53 months. RESULTS: Ectopic expression of NR4A2 increased the chemo-resistance, and attenuated the chemotherapeutics-induced apoptosis. Transient treatment of PGE2 significantly up-regulated NR4A2 expression via protein kinase A pathway and increased the chemo-resistance. NR4A2 expression in epithelials consecutively increased from adenoma, adjacent mucosa to CRC (P(trend)<0.001). In multivariate Cox regression analyses, high NR4A2 expression in cancer nuclei (immunoreactive score ≥ 4) significantly predicted a shorter disease-specific survival (DSS) of CRC patients (hazard ratio [HR]=1.88, P=0.024). High NR4A2 expression specifically predicted a shorter DSS of colon cancer patients (dichotomisation, HR=2.55, log-rank test P=0.011), especially for those who received postoperative 5-fluorouracil/leucovorin plus oxaliplatin (FOLFOX) chemotherapy (3-score range, HR=1.86, log-rank test P=0.020). CONCLUSION: High expression of NR4A2 in CRC cells confers chemo-resistance, attenuates chemotherapeutics-induced apoptosis, and predicts unfavorable prognosis of colon cancer patients, especially for those who received postoperative chemotherapy. NR4A2 may be prognostic and predictive for colon cancer.

Schizophrenia-like features in transgenic mice overexpressing human HO-1 in the astrocytic compartment.

Delineation of key molecules that act epigenetically to transduce diverse stressors into established patterns of disease would facilitate the advent of preventive and disease-modifying therapeutics for a host of neurological disorders. Herein, we demonstrate that selective overexpression of the stress protein heme oxygenase-1 (HO-1) in astrocytes of novel GFAP.HMOX1 transgenic mice results in subcortical oxidative stress and mitochondrial damage/autophagy; diminished neuronal reelin content (males); induction of Nurr1 and Pitx3 with attendant suppression of their targeting miRNAs, 145 and 133b; increased tyrosine hydroxylase and α-synuclein expression with downregulation of the targeting miR-7b of the latter; augmented dopamine and serotonin levels in basal ganglia; reduced D1 receptor binding in nucleus accumbens; axodendritic pathology and altered hippocampal cytoarchitectonics; impaired neurovascular coupling; attenuated prepulse inhibition (males); and hyperkinetic behavior. The GFAP.HMOX1 neurophenotype bears resemblances to human schizophrenia and other neurodevelopmental conditions and implicates glial HO-1 as a prime transducer of inimical (endogenous and environmental) influences on the development of monoaminergic circuitry. Containment of the glial HO-1 response to noxious stimuli at strategic points of the life cycle may afford novel opportunities for the effective management of human neurodevelopmental and neurodegenerative conditions.

Vitamin D and Parkinson's disease.

Parkinson's disease (PD) is the second most common form of neurodegeneration among the elderly population. PD is clinically characterized by tremors, rigidity, slowness of movement, and postural imbalance. Interestingly, a significant association has been demonstrated between PD and low levels of vitamin D in the serum, and vitamin D supplement appears to have a beneficial clinical effect on PD. Genetic studies have provided the opportunity to determine which proteins link vitamin D to PD pathology, e.g., Nurr1 gene, toll-like receptor, gene related to lipid disorders, vascular endothelial factor, tyrosine hydroxylase, and angiogenin. Vitamin D also exerts its effects on cancer through nongenomic factors, e.g., bacillus Calmette-Guerin vaccination, interleukin-10, Wntß-catenin signaling pathways, mitogen-activated protein kinase pathways, and the reduced form of the nicotinamide adenine dinucleotide phosphate. In conclusion, vitamin D might have a beneficial role in PD. Calcitriol is best used for PD because it is the active form of the vitamin D(3) metabolite and modulates inflammatory cytokine expression. Further investigation with calcitriol in PD is needed.

Ginkgo biloba extract (EGb 761) modulates the expression of dopamine-related genes in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinsonism in mice.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes nigrostriatal dopaminergic neurotoxicity and behavioral impairment in rodents similar to Parkinson's disease. The MPTP mouse model is widely used to evaluate new protective agents. EGb 761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves according to a standardized procedure. We have shown that EGb 761 attenuates the loss of striatal dopamine levels and prevents the neurodegeneration of the nigrostriatal pathway induced by MPTP. This finding shows that neuroprotective effects of EGb 761 act, in part, on the dopamine system. Therefore, this study investigates whether EGb 761 exerts dopaminergic neuroprotection through the regulation of dopamine-related gene expression in MPTP-induced Parkinsonism. Male C57BL/6J mice were injected with MPTP (30 mg/kg, i.p.) for 5 days and later with EGb 761 (40 mg/kg, i.p.) daily for 18 days. The expression of selected genes was evaluated in the striatum and midbrain by quantitative PCR. The genes for tyrosine hydroxylase (Th), vesicular monoamine transporter 2 (Vmat2), dopamine transporter (Dat), dopamine D2 receptor (Da-d2r), and transcription factors (Pitx3 and Nurr1) related to dopamine neurotransmission were selected for the analysis. EGb 761 administration to MPTP-treated mice protected Th (41%), Vmat2 (15%), Dat (102%), Da-d2r (46%), Pitx3 (63%), and Nurr1 (148%) mRNA levels in the midbrain, all of which were up-regulated. However, EGb 761 partially reversed the MPTP effect exclusively for Th (48%) and Nurr1 (96%) mRNA in the striatum. Only Th and Nurr1 mRNA and protein levels were regulated by EGb 761 in both regions of the nigrostriatal pathway. This result could be related to the regulation of their transcription. Our results suggest that EGb 761-associated neuroprotection against MPTP neurotoxicity is related to the regulation of the dopamine genes. Moreover, this neuroprotection also involves the regulation of transcription factors such as Nurr1 that are important for the functional maintenance of dopaminergic neurons.

Moracenin D from Mori Cortex radicis protects SH-SY5Y cells against dopamine-induced cell death by regulating nurr1 and α-synuclein expression.

In our efforts to find neuroprotective materials of plant origin, several compounds were isolated from Mori Cortex Radicis. The protective effect against dopamine-induced cell death was examined, and the subsequent effects on the levels of expression of Parkinson's disease-associated nurr1 and α-synuclein were evaluated in a dopamine-induced system. Five compounds were isolated and moracenin D protected cell death against dopamine-induction in human neuroblastoma SH-SY5Y cells. The effects of moracenin D on the levels of mRNA and protein expression of nurr1 and α-synuclein were subsequently examined using reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. Treatment with moracenin D resulted in an up-regulation of nurr1 mRNA levels and a down-regulation of α-synuclein mRNA levels. Additionally, the α-synuclein protein expression was decreased in accordance with an increase in nurr1 protein expression. These results demonstrate that the protective effects of moracenin D were presumably due to the correlative effects on the up-regulation of nurr1 and down-regulation of α-synuclein expressions against dopamine induction. Therefore, moracenin D can be considered as a candidate for therapy for Parkinson's disease.

Nurr1 is not essential for the development of prepulse inhibition deficits induced by prenatal immune activation.

Inflammation-induced disruption of fetal neurodevelopmental processes has been linked to the precipitation of long-lasting behavioral abnormalities and associated neuropathology. Recent longitudinal investigations in prenatal immune activation models have revealed developmental correspondences between the ontogeny of specific dopaminergic neuropathology and the postnatal onset of distinct forms of dopamine-dependent functional abnormalities implicated in schizophrenia. Two examples of such developmental correspondences are increased expression of the orphan nuclear receptor Nurr1 (NR4A2) in ventral midbrain areas and disruption of prepulse inhibition of the acoustic startle reflex, with both the neuroanatomical and behavioral effects emerging only in adult but not pre-pubertal subjects exposed to prenatal maternal inflammation. In the present study, we tested the hypothesis that Nurr1 may be a critical molecular mediator of prepulse inhibition deficits induced by prenatal immune activation. To this end, we compared the effects of prenatal immune challenge on adult PPI in wild-type (wt) mice and mice with a heterozygous constitutive deletion of Nurr1 (Nurr1+/-) using a well established mouse model of maternal immune activation by exposure to the viral mimetic poly(I:C) (=polyriboinosinic-polyribocytidilic acid). We found that prenatal poly(I:C) treatment on gestation day 9 was similarly effective in disrupting prepulse inhibition in adult wt and Nurr1+/- mice. Prenatal poly(I:C) treatment also generally increased midbrain Nurr1-positive cells and counteracted the genetically driven Nurr1 deficit in the substantia nigra. Our data thus suggest that at least under the present experimental conditions, Nurr1 is not essential for the development of prepulse inhibition deficits induced by prenatal immune activation.

Effect of Bushen Huoxue Decoction on the orphan receptor and tyrosine hydroxylase in the brain of rats with Parkinson's disease.

OBJECTIVE: To explore the effect of Bushen Huoxue Decoction (BHD) on the orphan receptor (Nurr1) and tyrosine hydroxylase (TH) in the brain of rats with Parkinson's disease (PD). METHODS: One hundred and twenty SD rats were divided into 100 in the model group and 20 in the normal control group, fifty-eight SD rats from the model group, established into PD model successfully by injuring their substantia nigra (SSN) with 6-hydroxydopamine, were divided equally into the model group and the test group, and they were treated with saline and BHD, respectively, for eight successive weeks. The change in the rats' behavior before and after treatment was observed by counting the cycles of rotation induced by apomorphine injection; the pathology of neurons, level of Nurr1 mRNA expression, and amount of TH positive cells in SSN were observed after treatment. RESULTS: The rats' behavior was improved in the tested group significantly, the rotation cycle after treatment being 84.0 ± 20.0 cycles/40 min, which was significantly lower than that in the model group (377.0 ± 62.3 cycles/40 min, P<0.01). Besides, the Nurr1 mRNA expression and TH positive cell in the test group were 0.97 ± 0.15 and 49.40 ± 14.72, respectively, which were significantly higher than those in the model group, 0.22 ± 0.03 and 5.45 ± 2.58, respectively (all P<0.01). CONCLUSION: BHD could treat PD by enhancing the Nurr1 mRNA expression, increasing the TH content in brain, and promoting the repairing of injured neuron in cerebral SSN.