Gastrodin inhibits neuroinflammation in rotenone-induced Parkinson's disease model rats

The present study showed that the latency of rats moving on a vertical grid was significantly prolonged, and the number of rats sliding down from the declined plane was increased remarkably, in rotenone-induced Parkinson＇s disease model rats compared with control rats. The moving latency recovered to normal levels, but the number of slides was significantly increased at 28 days after model establishment. The slope test is a meaningful approach to evaluate the symptoms of Parkinson＇s disease model rats treated with rotenone. In addition, loss of substantia nigral dopaminergic neurons in model rats was observed at 1 day after the model was established, and continued gradually at 14 and 28 days. The expression of tyrosine hydroxylase-positive cells was significantly increased in gastrodin-treated rats at 14 days. Significant numbers of activated microglia cells were observed in model rats at 14 and 28 days; treatment of rats with Madopar at 28 days suppressed microglial activation. Treatment of rats with gastrodin or Madopar at 28 days significantly reduced interleukin-1β expression. The loss of substantia nigral dopaminergic neurons paralleled the microglial activation in Parkinson＇s disease model rats treated with rotenone. The inflammatory factors tumor necrosis factor-a and interleukin-1β are involved in the substantia nigral damage. Gastrodin could protect dopaminergic neurons via inhibition of interteukin-1β expression and neuroinflammation in the substantia nigra.

Effect of moxibustion on mTOR-mediated autophagy in rotenone-induced Parkinson's disease model rats

Defects in autophagy-mediated clearance of α-synuclein may be one of the key factors leading to progressive loss of dopaminergic neurons in the substantia nigra. Moxibustion therapy for Parkinson’s disease has been shown to have a positive effect, but the underlying mechanism remains unknown. Based on this, we explored whether moxibustion could protect dopaminergic neurons by promoting autophagy mediated by mammalian target of rapamycin （mTOR）, with subsequent elimination of α-syn. A Parkinson’s disease model was induced in rats by subcutaneous injection of rotenone at the back of their necks, and they received moxibustion at Zusanli （ST36）, Guanyuan （CV4）and Fengfu （GV16）, for 10 minutes at every point, once per day, for 14 consecutive days. Model rats without any treatment were used as a sham control. Compared with the Parkinson’s disease group, the moxibustion group showed significantly greater tyrosine hydroxylase immunoreactivity and expression of light chain 3-II protein in the substantia nigra, and their behavioral score, α-synuclein immunoreactivity,the expression of phosphorylated mTOR and phosphorylated ribosomal protein S6 kinase （p-p70S6K） in the substantia nigra were significantly lower. These results suggest that moxibustion can promote the autophagic clearance of α-syn and improve behavioral performance in Parkinson’s disease model rats. The protective mechanism may be associated with suppression of the mTOR/p70S6K pathway.

H_2O_2预处理抑制α-Synuclein的聚集并减轻Rotenone对PC12细胞的损伤

目的探讨H2O2预处理(HPP)对Rotenone诱导PC12细胞损伤及α-Synuclein聚集的影响。方法采用四甲基偶氮唑盐法(MTT法)、流式细胞仪、免疫印迹(western blot)技术及共聚焦显微镜分别检测细胞活力、细胞凋亡率、α-Synuclein的表达及聚集。结果H2O2预处理能够减少α-Synuclein寡聚体的表达及聚集体的形成,增加PC12细胞活力(Rot组47%±3.67%,HPP+Rot组82%±6.69%),抑制细胞凋亡(Rot组49.68%±4.55%,HPP+Rot组18.73%±5.64%)。结论H2O2预处理能减轻Rotenone对PC12细胞的毒性损伤作用,这种保护作用可能是通过抑制α-Synuclein寡聚体表达实现的。

Parallel relationship between microglial activation and substantia nigra damage in a rotenone-induced Parkinson's disease rat model

BACKGROUND： Inflammatory injury induced by microglial activation plays an important role in the occurrence and development of Parkinson＇s disease （PD）. However, few studies have examined the relationship between microglia and substantia nigra damage or dopaminergic neuron loss in animals with rotenone-induced PD.OBJECTIVE： To explore the relationship between activated microglia and loss of the substantia nigra, and the changes in concentration and dose of rotenone in the brain of rats with rotenone-induced PD.DESIGN, TIME AND SETTING： The neuropathological experiment was performed at the School of Traditional Chinese Medicine, Capital Medical University, China, from July 2007 to July 2008. MATERIALS： Rotenone was purchased from Sigma, USA. METHODS： The Parkinson＇s model was induced by injection of a rotenone oily-emulsion （2 mg/kg daily） subcutaneously into the back of 58 male adult Wistar rats for 3-6 weeks. Another three rats served as normal controls.MAIN OUTCOME MEASURES： Neurobehavioral changes were observed and recorded following rotenone treatment. Tyrosine hydroxylase and complement receptor OX42 were separately analyzed by immunohistochemical staining within 4 weeks following stopping rotenone treatment. Rotenone content was measured using high performance liquid chromatography in the cerebellum of rats that scored 2.4-6.RESULTS： Rotenone induced a loss of dopaminergic neurons in the substantia nigra as well as microglial activation, with increased behavior scores. Dopaminergic loss was still ongoing even when rotenone was stopped. Dopaminergic neuronal degeneration in the substantia nigra was initially 6%, but was 85% at 2 weeks after scoring, and degeneration depended on activated microglia. Rotenone was detected in the cerebellum at concentrations between 78.9 μg/L and 309.6 μg/L. CONCLUSION： Nigrostriatal dopaminergic degeneration paralleled the microglial activation. Rotenone absorbed into the brain in its original form initiated pathological injury in the substantia niara of PD rats.

Neurotoxicity of the pesticide rotenone on neuronal polarization: a mechanistic approach

Neurons are the most extensive and polarized cells that display a unique single long axon and multiple dendrites, which are compartments exhibiting structural and functional differences. Polarity occurs early in neuronal development and it is maintained by complex subcellular mechanisms throughout cell life. A well-defined and controlled spatio-temporal program of cellular and molecular events strictly regulates the formation of the axon and dendrites from a non-polarized cell. This event is critical for an adequate neuronal wiring and therefore for the normal functioning of the nervous system. Neuronal polarity is very sensitive to the harmful effects of different factors present in the environment. In this regard, rotenone is a crystalline, colorless and odorless isoflavone used as insecticide, piscicide and broad spectrum pesticide commonly used earlier in agriculture. In the present review we will summarize the toxicity mechanism caused by this pesticide in different neuronal cell types, focusing on a particular biological mechanism whereby rotenone could impair neuronal polarization in cultured hippocampal neurons. Recent advances suggest that the inhibition of axonogenesis produced by rotenone could be related with its effect on microtubule dynamics, the actin cytoskeleton and their regulatory pathways, particularly affecting the small RhoGTPase RhoA. Unveiling the mechanism by which rotenone produces neurotoxicity will be instrumental to understand the cellular mechanisms involved in neurodegenerative diseases influenced by this environmental pollutant, which may lead to research focused on the design of new therapeutic strategies.

Determination of Rotenone Residues in Foodstuffs by Solid-Phase Extraction (SPE) and Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS)

We developed a novel approach to determine rotenone residues in foodstuffs, by integrating solid-phase extraction （SPE） and liquid chromatography/tandem mass spectrometry （LC-MS/MS） technologies, to achieve high sensitivity and selectivity. In our method, the solvent extraction with n-hexane-dichloromethane （50：50, v/v） and cleanup with florisil SPE cartridges using ethyl acetate-ethyl ether （25：75, v/v） as eluents provided adequate recovery of rotenone. The detection of rotenone was then carried out by LC-MS/MS using acetonitrile-water with the 0.1% formic acid （w/v） as the mobile phase. The multiple reaction monitoring （MRM） scheme employed in the approach involved the transitions of the precursor ion to three selected product ions, in which one pair for quantification was m/z 395.3 〉 213.2 and the other two pairs for identification were m/z 395.3 〉 192.2 and 395.3 〉 367.0. The limits of quantification （LOQs） of the method ranged from 0.001 to 0.005 mg kg-1 depending on the matrix. Intra- and inter-day precisions （relative standard deviations, RSDs） for rotenone were less than 7.1 and 14.8%, respectively. Results from repetitive analysis suggested good reproducibility of the method for rotenone residue detection. The recoveries at three concentrations （LOQ, 10LOQ and 100LOQ） ranged from 79.3-118.3% in cabbage, potato, onion, carrot, apple, orange, banana, lichee, tea, and Shiitake mushroom. The proposed procedure was then applied to the analysis of 129 real samples collected from Xiamen, Fujian Province, China. The existence of rotenone was found in two tea products with concentrations of 0.012 and 0.016 mg kg-1, respectively. The method has great potential for routine analysis of monitoring rotenone residue in foodstuffs.

Effect of rifampicin pre-and post-treatment on rotenone-induced dopaminergic neuronal apoptosis and alpha-synuclein expression

BACKGROUND： Rifampicin inhibits the formation of a-synuclein multimer and protects against 1-methyl-4-phenyl-1,2, 3, 6-tetrahydropyritine （MPTP）-induced PC12 cell apoptosis. OBJECTIVE： To compare the effect of rifampicin pre- and post-treatment on tyrosine hydroxylase and α-synuclein expression in substantia nigra pars compacta in a rat model of Parkinson＇s disease. DESIGN, TIME AND SE＇B＇ING： A randomized, controlled experiment was performed at the Experimental Animal Center of Sun Yat-sen University North Campus （China） from November 2006 to October 2008. MATERIALS： Rifampicin was purchased from MD, USA; rotenone was purchased from Sigma, USA; mouse anti-rat α-synuclein monoclonal antibody was purchased from B＆D, USA; and rabbit anti-rat tyrosine hydroxylase monoclonal antibody was purchased from Chemicon, USA. METHODS： A total of 72 male, Sprague Dawley rats, aged 8 weeks, were randomly assigned to 5 groups： blank control （n = 12）, rifampicin （n = 12）, rotenone （n = 16）, rifampicin pre-treatment （n = 16）, and rifampicin post-treatment （n = 16）. Parkinson＇s disease model rats were established via a subcutaneous injection of rotenone （1.5 mg/kg per day） in the three treatment groups, once a day for 3 successive weeks. Rifampicin （30 mg/kg per day） was intragastrically administered in the rifampicin pre-treatment group 3 days prior to rotenone induction and in the rifampicin post-treatment group 7 days after rotenone induction. Rats were treated with a subcutaneous injection of 1 mL/kg per day sunflower oil in the blank control group and an intragastric injection of 30 mg/kg per day rifampicin in the rifampicin group, once a day for 3 successive weeks in total. MAIN OUTCOME MEASURES： Prior to treatment and in the end of the 3^rd week after treatment, the rats were evaluated using the modified neurological severity score. The substantia nigra from the rats was extracted for hematoxylin-eosin staining. Western blot analysis was performed to determine tyrosine hydroxylase and α-synuclein expression. RESULTS： Hematoxylin-eosin staining revealed a significant reduction in the number of substantia nigral neurons in the rotenone group, in addition to neurodegradation, hypopigmentation, and pyknosis. In the rifampicin pre-treatment and post-treatment groups, the number of dopaminergic neurons was significantly increased compared with the rotenone group （P 〈 0.01）, with slight neuronal damage. Compared with the rotenone group, substantia nigral tyrosine hydroxylase expression was significantly increased in the rifampicin pre-treatment and post-treatment groups （P 〈 0.01）, but α-synuclein expression and modified neurological severity scores were significantly decreased （P 〈 0.01）. In addition, the effect of rifampicin in the pre-treatment group was superior to the post-treatment group. There was no significant difference in tyrosine hydroxylase and α-synuclein expression, or in the modified neurological severity scores, between the blank control and rifampicin groups （P 〉 0.05）. CONCLUSION： Rifampicin significantly attenuated neuropathological and behavioral motor deficits induced by rotenone. Moreover, rifampicin enhanced tyrosine hydroxylase expression, but inhibited α-synuclein expression. The effect of rifampicin pre-treatment was superior to rifampicin post-treatment.

Bougainvillea spectabilis flowers extract protects against the rotenone-induced toxicity

Objective:To investigate the effect of two extracts of Bougainvillea spectabilis(B. spectabilis) flowers with yellow and pink/purple on brain oxidative stress and neuronal damage caused in rats by systemic rotenone injection. Methods:Rotenone 1.5 mg/kg was given three times per week alone or in combination with B. spectabilis flowers extracts(25 mg or 50 mg) via the subcutaneous route for 2 weeks. Brain concentrations of the lipid peroxidation marker malondialdehyde(MDA),reduced glutathione,nitric oxide(nitrite),the pro-inflammatory cytokine interleukin-1beta(Il-1β) as well as butyrylcholinesterase,and paraoxonase-1(PON-1) activities,were determined. Histopathology and caspase-3 immunohistochemistry were also performed. Results:Rotenone resulted in significant increases of brain MDA(the product of lipid peroxidation),and nitric oxide content along with decreased brain reduced glutathione. There were also marked and significant inhibition of brain PON-1 and BCh E activities and increased Il-1β in brain of rotenone-treated rats. B. spectabilis flowers extract itself resulted in brain oxidative stress increasing both lipid peroxidation and nitrite content whilst inhibiting PON-1 activity. The yellow flowers extract inhibited BCh E activity and increased brain Il-1β. When given to rotenone-treated rats,B. spectabilis extracts,however,decreased lipid peroxidation while their low administered doses increased brain GSH. Brain nitrite decreased by the pink extract but showed further increase by the yellow extract. Either extract,however,caused further inhibition of PON-1 activity while the yellow extract resulted in further inhibition of BChE activity. Histopathological studies indicated that both extracts protected against brain,liver and kidney damage caused by the toxicant. Conclusions:These data indicate that B. spectabilis flowers extracts exert protective effect against the toxic effects of rotenone on brain,liver and kidney. B. spectabilis flowers extracts decreased brain lipid peroxidation and prevented neuronal death due to rotenone and might thus prove the value in treatment of Parkinson's disease.

Rifampicin inhibits apoptosis in rotenone-induced differentiated PC12 cells by ameliorating mitochondrial oxidative stress

BACKGROUND： Previous studies have shown that rifampicin exhibits neuroprotective effects, but the precise mechanisms remain unclear. Rifampicin is thought to exert the neuroprotective effect as a hydroxyl free radical scavenger. OBJECTIVE： To investigate the protective effects of rifampicin pretreatment on rotenone-induced mitochondrial oxidative stress in differentiated PC12 cells.DESIGN, TIME AND SETrlNG： A repeated measure, cell-based study was performed at the Department of Neurology, Second Affiliated Hospital, Sun Yat-sen University, China between December 2007 and November 2008. MATERIALS： PC12 cells were a kind gift from the Physiology Laboratory of Zhongshan Medical School, Sun Yat-sen University, China. Rotenone and rifampicin were purchased from Sigma, USA. METHODS： PC12 cells were differentiated by culturing with 100 ng/mL 7S nerve growth factor for 9 days in Dulbecco＇s modified Eagle＇s medium/Nutrient Mix F12 （DMEM/F12） supplemented with 10% fetal bovine serum. The cells were assigned to six groups according to various treatment conditions： control, cultured with normal media; rifampicin group, treated with 300 pmol/L rotenone for 26 hours; rotenone group, treated with 2.5 pmol/L rotenone for 24 hours; rifampicin pretreatment groups, pretreated with 100, 200, and 300 pmol/L rifampicin for 2 hours, respectively, followed by 2.5 μmol/L rotenone for 24 hours.MAIN OUTCOME MEASURES： Mitochondrial membrane potential was measured by fluorescence microscopy and flow cytometry, respectively, using rhodamine123 staining. Intracellular reactive oxygen species formation was analyzed by flow cytometry using 2＇, 7＇-dichlorofluorescin-diacetate staining, and intracellular reduced glutathione was measured with a microplate reader. Cell viability was determined by 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide assay. Cell apoptosis was detected by Hoechst 33342 staining and flow cytometry. RESULTS： Increased apoptosis in rotenone-induced, differentiated, PC12 cells was accompanied by the loss of mitochondrial transmembrane potential, the formation of reactive oxygen species, and reduced glutathione depletion （P 〈 0.01）. Rotenone-induced mitochondrial dysfunction was blocked in a dose-dependent manner by rifampicin （P 〈 0.05 or P 〈 0.01）, CONCLUSION： Pretreatment of differentiated PC12 cells with rifampicin blocked rotenone-induced apoptosis by ameliorating mitochondrial dysfunction and oxidative stress.

Detecting dopaminergic neuronal degeneration using diffusion tensor imaging in a rotenone-induced rat model of Parkinson's disease: fractional anisotropy and mean diffusivity values

Dopamine content in the basal ganglia is strongly associated with the degree of dopaminergic neuron loss in the substantia nigra pars com- pacta. Symptoms of Parkinson＇s disease might not arise until more than 50% of the substantia nigra pars compacta is lost and the dopamine content in the basal ganglia is reduced by more than 80%. Greater diagnostic sensitivity and specificity would allow earlier detection of Parkinson＇s disease. Diffusion tensor imaging is a recently developed magnetic resonance imaging technique that measures mean diffusiv- ity and fractional anisotropy, and responds to changes in brain microstructure. When the microscopic barrier （including cell membranes, microtubules and other structures that interfere with the free diffusion of water） is destroyed and extracellular fluid volume accumulates, the mean diffusivity value increases; when the integrity of the microstructure （such as myelin） is destroyed, fractional anisotropy value decreases. However, there is no consensus as to whether these changes can reflect the early pathological alterations in Parkinson＇s disease. Here, we established a rat model of Parkinson＇s disease by injecting rotenone （or sunflower oil in controls） into the right suhstantia nigra. Diffusion tensor imaging results revealed that in the stages of disease, at 1, 2, 4, and 6 weeks after rotenone injection, fiactional anisotropy value decreased, but mean diffusivity values increased in the right substantia nigra in the experimental group. Fractional anisotropy values were lower at 4 weeks than at 6 weeks in the right substantia nigra of rats from the experimental group. Mean diffusivity values were mark- edly greater at 1 week than at 6 weeks in the right corpus striatum of rats from the experimental group. These findings suggest that mean diffusivity and fractional anisotropy values in the brain of rat models of Parkinson＇s disease 4 weeks after model establishment can reflect early degeneration of dopaminergic neurons. ＇The change in fractional anisotropy values after destruction of myelin integrity is likely to be of greater early diagnostic significance than the change in mean diffusivity values.

Differences in brain pathological changes between rotenone and 6-hydroxydopamine Parkinson＇s disease models

Rotenone and 6-hydroxydopamine are two drugs commonly used to generate Parkinson＇s disease animal models.They not only achieve degenerative changes of dopaminergic neurons in the substantia nigra,but also satisfy the requirements for iron deposition.However,few studies have compared the characteristics of these two models by magnetic resonance imaging.In this study,rat models of Parkinson＇s disease were generated by injection of 3 μg rotenone or 10 μg 6-hydroxydopamine into the right substantia nigra.At 1,2,4,and 6 weeks after injection,coronal whole-brain T2-weighted imaging,transverse whole-brain T2-weighted imaging,and coronal diffusion tensor weighted imaging were conducted to measure fractional anisotropy and T2＊ values at the injury site.The fractional anisotropy value on the right side of the substantia nigra was remarkably lower at 6 weeks than at other time points in the rotenone group.In the 6-hydroxydopamine group,the fractional anisotropy value was decreased,but T2＊ values were increased on the right side of the substantia nigra at 1 week.Our findings confirm that the 6-hydroxydopamine-induced model is suitable for studying dopaminergic neurons over short periods,while the rotenone-induced model may be appropriate for studying the pathological and physiological processes of Parkinson＇s disease over long periods.

Mechanisms of rotenone-induced neurotoxicity in PC 12 cells

BACKGROUND： Rotenone-induced neurotoxicity in PC 12 cells has been widely used to study the pathogenesis of Parkinson＇s disease. However, the precise mechanisms underlying rotenone-induced dopaminergic neuronal degeneration in Parkinson＇s disease remains unclear. OBJECTIVE： To establish rotenone-induced neurotoxicity in PC 12 cells, and to investigate the possible action pathways to rotenone-induced neural cell injury at the protein level. DESIGN, TIME AND SETTING： A controlled proteomics study was performed at the Department of Neurology, First Hospital, Jilin University between March 2006 and March 2007. MATERIALS： PC 12 cells were obtained from Shanghai Cell Bank of Chinese Academy of Sciences, China. Rotenone was provided by Sigma, USA. METHODS： PC 12 cells in logarithmic growth phase were treated under experimental and control conditions, respectively. A total of 0.5 μmol/L rotenone, or the same amount of Dulbecco＇s modified eagle＇s medium （DMEM）, was added in the experimental and control conditions, respectively. MAIN OUTCOME MEASURES： Following 72 hours of rotenone treatment, cellular survival rate was determined by methyl thiazolyl tetrazolium assay, and apoptotic changes were detected by Hoechst 33342 staining. Total cellular protein was extracted to acquire differential protein expression data utilizing two-dimensional differential in-gel electrophoresis. To identify differential protein spots, matrix-assisted laser desorption/ionization-time of flight mass spectrometry （MALDI-TOF-MS） was used. RESULTS： In the MTT assay, the experimental condition induced significantly less cell survival compared to the control condition （P 〈 0.01）. Hoechst 33342 staining revealed a larger number of apoptotic cells under the experimental condition compared to the control condition （P 〈 0.01）, as determined by the presence of nuclear condensation, pyknosis, and nuclear fragmentation. Two-dimensional electrophoresis results showed that the differential expression of protein spots 1069 and 1538 was increased by 144% and 124%, respectively, while that of protein spot 1094 was decreased by 123% in the experimental condition compared to the control condition （P 〈 0.01）. By MALDI-TOF-MS analysis and database retrieval, γ-enolase, triosephosphate isomerase 1, and eukaryotic translation initiation factor 4A were confirmed to be involved in rotenone-induced neural cell injury. CONCLUSION： γ-enolase, triosephosphate isomerase 1, and eukaryotic translation initiation factor 4A might participate in rotenone-induced neurotoxicity in PC 12 cells.

Neuroprotection by misoprostol against rotenone-induced neurotoxicity in rat brain

Objective: To investigate the effect of the prostaglandin E1 analogue misoprostol on oxidative stress and neurodegeration caused by subcutaneous rotenone administration in rats. Methods:Rotenone was administered in a dose of 1.5 mg/kg every other day for 2 weeks. Starting from the 1 st day of rotenone injection, rats were subcutaneously treated with misoprostol at doses of10, 100 or 1 000 μg/kg. Rats were evaluated for brain lipid peroxidation(malondialdehyde:MDA), reduced glutathione(GSH), nitric oxide(NO) levels, and paraoxonase-1(PON-1) activity.The concentrations of the anti-apoptotic protein B cell/lymphoma-2(Bcl-2) were determined in the striatum. Histopathologic examination and the expression of inducible nitric oxide synthase(iNOS) in the cerebral cortex and striatum were also performed. Results: Compared with the vehicle-treated group, rotenone caused a significant increase in brain lipid proxidation(MDA)by 61%(P<0.05) accompanied by an increase in NO by 73.1%(P<0.05) and a decrease in GSH concentration by 29.4%(P<0.05). In addition, brain PON-1 activity significantly decreased by63.0%(P<0.05) and striatal Bcl-2 significantly decreased by 27.9%(P<0.05) with respect to the corresponding control value. Brain sections from rotenone treated rats showed extensive dark pyknotic and apoptotic nuclei in neurons, shrunken cytoplasm and perineuronal vacuolation.Rotenone also caused pronounced expression of iNOS in the cerebral cortex and striatum.Treatment with misoprostol at doses of 100 and 1 000 μg/kg resulted in decreased brain MDA(by 16.5%-23.0%)(P<0.05) and NO levels(by 37.1%-40.7%)(P<0.05) and increased GSH concentrations(by 18.8%-30.1%)(P<0.05). PON-1 activity was significantly increased by80.0%-114.8%(P<0.05) by misoprostol at 100 and 1 000 μg/kg, respectively. In addition,misoprostol treatment restored striatal Bcl-2 concentrations to its normal value. Misoprostol treatment resulted in markedly reduced brain injury and decreased iNOS expression in the cerebral cortex and striatum of rotenone intoxicated rats. Conclusions: These data suggest that misoprostol prevents the rotenone-induced neurodegeneration in rat brain by reducing brain oxidative stress.

Geniposide prevents rotenone-induced apoptosis in primary cultured neurons

Geniposide, a monomer extracted from gardenia and widely used in Chinese medicine, is a novel agonist at the glucagon-like peptide-1 receptor. This receptor is involved in neuroprotection. In the present study, we sought to identify an anti-apoptotic mechanism for the treatment of neurodegenerative diseases. Primary cultured neurons were treated with different concentrations of rotenone for 48 hours. Morphological observation, cell counting kit-8 assay, lactate dehydrogenase detection and western blot assay demonstrated that 0.5 n M rotenone increased lactate dehydrogenase release, decreased the expression of procaspase-3 and Bcl-2, and increased cleaved caspase-3 expression in normal neurons. All these effects were prevented by geniposide. Our results indicate that geniposide diminished rotenone-induced injury in primary neurons by suppressing apoptosis. This may be one of the molecular mechanisms underlying the efficacy of geniposide in the treatment of neurodegenerative diseases.

The Pael-R gene does not mediate the changes in rotenone-induced Parkinson's disease model cells

In this study, we established cell models for Parkinson＇s disease using rotenone. An RNA interfer- ence vector targeting Parkin-associated endothelin receptor-like receptor （Pad-R） was transfected into the model cells. The results of reverse-transcription polymerase chain reaction and western blot analysis showed that Pael-R expression was decreased after RNA interference compared with the control group （no treatment） and the model group （rotenone treatment）, while the rate of apoptosis and survival of dopaminergic cells did not differ significantly between groups, as detected by flow cytometry and an MTT assay. These experimental findings indicate that the Pael-R gene has no role in the changes in rotenone-induced Parkinson＇s disease model cells.

Luteolin protects PC12 cells from rotenone-induced apoptosis

The 4-hydroxy-flavonoid compound luteolin is a phytoestrogen with antioxidant, anti-inflammatory, and anti-tumor properties. The present study analyzed the protective effects of luteolin against rotenone-induced PC12 cell apoptosis in a model of Parkinson＇s disease （PD）. Rotenone （1.6 μmol/L） was utilized to establish the In vitro PD model, resulting in low cell viability and an apoptotic rate of 36.1%. Luteolin （100 μmol/L） pretreatment significantly ameliorated rotenone-induced damage, improved cell morphology and viability, decreased comet tail length, reduced the rate of apoptosis （11.8%）, and down-regulated cleaved caspase-3 expression. Results demonstrate that luteolin protects PC12 cells against rotenone-induced apoptosis by decreasing cleaved caspase-3 expression.

Novel compound FLZ alleviates rotenone-induced Parkinson disease model by sup⁃pressing TLR4/MyD88/NF-κB pathway through microbiota-gut-brain axis

OBJECTIVES Parkinson disease(PD)is the second most common neurodegener⁃ative disease,but none of the current treatments for PD could halt the progress of the disease due to the limited understanding of the pathogenesis.Increasing evidence proves that the close com⁃munication between the brain and the gastroin⁃testinal system is influenced by gut microbiota in PD pathogenesis,known as microbiota-gut-brain axis.However,the explicit mechanisms of micro⁃biota dysbiosis in PD development have not been well elucidated yet.FLZ,a novel squamosamide derivative,has been proved to be effective in many PD models and is undergoing the phaseⅠclinical trial to treat PD in China.The aims of our study are to assess the neuroprotective effects of FLZ treatment on PD and to further explore the underlying microbiota-related mechanisms of PD by using FLZ as a tool.METHODS Chronic administration of rotenone(30 mg·kg-1 per day)was utilized to induce a mouse model to mimic the pathological process of PD.Behavioral tests and gastrointestinal function tests were conduct⁃ed to evaluate the PD symptoms.Gut microbiota alterations were analyzed by 16s rRNA sequenc⁃ing.The intestinal permeability and blood-brain barrier structures were assessed by various methods.The pro-inflammatory cytokines and LPS levels in the colon,serum,and brain were detected by ELISA.Furthermore,the levels of in⁃flammation and TLR4/MyD88/NF-κB pathway in the substantia nigra(SN)and colon were mea⁃sured.RESULTS Behavioral tests and gastroin⁃testinal function tests found that rotenone-in⁃duced mice showed gastrointestinal dysfunctions(week 3)prior to the motor deficits(week 4).However,FLZ treatment significantly alleviated these PD symptoms.16S rRNA sequencing illus⁃trated that PD-related microbiota alterations in⁃duced by rotenone were reversed by FLZ treatment at various taxa levels.Especially,we identified an increased genus Akkermansia in the Rotenone group(P=0.0006),which could be reversed by FLZ administration(P=0.0070).By reducing microbiota dysbiosis,qPCR results showed that FLZ treatment suppressed intestinal inflammation of rotenone-challenged mice.After⁃wards,transmission electron microscopy(TEM),in vivo FITC permeability assay,bacterial translocation assay,and Western blotting togeth⁃er suggested that FLZ treatment attenuated the intestinal barrier destruction induced by rote⁃none.Subsequently,ELISA results showed that FLZ administration inhibited the leakage of pro-inflammatory cytokines(TNF-α,IL-1β,and IL-6)and LPS into the serum,suggesting the atten⁃uation of systemic inflammation.Then,several experiments including TEM analysis found that FLZ treatment restored blood-brain barrier struc⁃ture.Consequently,the immunofluorescence staining demonstrated that neuroinflammation(increased Iba-1+and GFAP+cells)and dopami⁃nergic neuronal death(reduced TH+cells)in the SN caused by rotenone were remarkably attenu⁃ated.Further mechanistic research proved that the anti-inflammatory effects of FLZ administra⁃tion were mediated through the TLR4/MyD88/NF-κB pathway both in the SN and colon.CONCLU⁃SION FLZ treatment ameliorates microbiota dys⁃biosis to protect the PD model via inhibiting TLR4 pathway,which contributes to one of the underlying mechanisms beneath its neuroprotec⁃tive effects.Our research also supports the importance of microbiota-gut-brain axis in PD pathogenesis,suggesting its potential role as a novel therapeutic target for PD treatment.

Rotenone induces more serious learning and memory impairment than α-synuclein A30P does in Drosophila

Parkinson’s disease （PD） is a heterogenous disease caused by multifactorial etiology. PD is characterized by the loss of dopaminergic （DA） neurons in the substantia nigra and the accumulation of Lewy bodies. In this study, two Drosophila PD models by exposing Drosophila to rotenone （sporadic PD models） are proposed, and the human α-synuclein A30P protein （family PD models） in Drosophila is expressed respectively. Both models recapitulated the main human PD symptoms including the loss of dopaminergic neurons in the brain and severe locomotor deficits. Our study finds that Rotenone induces more serious learning and memory impairment than α-synuclein A30P does.

Curcumin protects against rotenone-induced neurotoxicity in cell and drosophila models of Parkinson’s disease

Parkinson’s disease (PD) is a progressive neurodegenerative movement disorder resulting from a selective loss of dopaminergic neurons. The pathogenesis of PD remains incompletely understood, but increasing evidence from human and animal studies has suggested that oxidative damage contributes to the neuronal loss in PD. In this study, we used rotenone (a mitochondrial complex I inhibitor) based cell and Drosophila models that resemble some key pathological features of PD to test whether curcumin, a potent antioxidant compound, derived from the curry spice turmeric, could protect against rotenone-induced neuronal toxicity. We found that curcumin reduced rotenone induced cell death in SH-SY5Y human neuroblastoma cells and alleviated PD-like symptoms in drosophila via reducing the intracellular and mitochondrial reactive oxygen species (ROS) levels and inhibiting the caspase-3/caspase-9 activity. These results suggest that curcumin is a promising therapeutic compound for PD.

Studies on Parkinson’s-Disease-Linked Genes, Brain Urea Levels and Histopathology in Rotenone Induced Parkinson’s Disease Rat Model

Parkinson’s disease (PD) is a debilitating neurological disorder that affects the aged population globally. This study aimed to explore how oral- and intraperitoneal-rotenone-induced PD alters brain urea levels, histopathology, and key Parkinsonism-related genes in the striatum. Hematoxylin and eosin staining was performed for histopathology assessment and real-time polymerase chain reaction was performed for gene expression. Rotenone 3 mg/kg body weight (Rot-3-ip) for 21 days and rotenone 50 mg/kg body weight (Rot-50-po) for 28 days significantly (p < 0.05) altered alpha-synuclein and tyrosine hydroxylase protein expression and Snca, Becn1 and Prkaa1 gene expression in the striatum. Lewy bodies were visible in both Rot-3-ip and Rot-50-po rat brains. There were contrasting features in brain and liver histopathology between the oral and intraperitoneal rotenone treatment groups. However, there was no significant (p < 0.05) difference in the brain urea levels between intraperitoneal and oral rotenone treatment groups. The propagation of PD through oral and intraperitoneal rotenone can have different impacts on the pathological sequence of events based on the molecular approach.