Chronic Administration Of Rotenone Research Articles

Neurodegeneration in the centrally-projecting Edinger\u2013Westphal nucleus contributes to the non-motor symptoms of Parkinson\u2019s disease in the rat

BackgroundThe neuropathological background of major depression and anxiety as non-motor symptoms of Parkinson’s disease is much less understood than classical motor symptoms. Although, neurodegeneration of the Edinger–Westphal nucleus in human Parkinson’s disease is a known phenomenon, its possible significance in mood status has never been elucidated. In this work we aimed at investigating whether neuron loss and alpha-synuclein accumulation in the urocortin 1 containing (UCN1) cells of the centrally-projecting Edinger–Westphal (EWcp) nucleus is associated with anxiety and depression-like state in the rat.MethodsSystemic chronic rotenone administration as well as targeted leptin–saporin-induced lesions of EWcp/UCN1 neurons were conducted. Rotarod, open field and sucrose preference tests were performed to assess motor performance and mood status. Multiple immunofluorescence combined with RNAscope were used to reveal the functional–morphological changes. Two-sample Student’s t test, Spearman’s rank correlation analysis and Mann–Whitney U tests were used for statistics.ResultsIn the rotenone model, besides motor deficit, an anxious and depression-like phenotype was detected. Well-comparable neuron loss, cytoplasmic alpha-synuclein accumulation as well as astro- and microglial activation were observed both in the substantia nigra pars compacta and EWcp. Occasionally, UCN1-immunoreactive neuronal debris was observed in phagocytotic microglia. UCN1 peptide content of viable EWcp cells correlated with dopaminergic substantia nigra cell count. Importantly, other mood status-related dopaminergic (ventral tegmental area), serotonergic (dorsal and median raphe) and noradrenergic (locus ceruleus and A5 area) brainstem centers did not show remarkable morphological changes. Targeted partial selective EWcp/UCN1 neuron ablation induced similar mood status without motor symptoms.ConclusionsOur findings collectively suggest that neurodegeneration of urocortinergic EWcp contributes to the mood-related non-motor symptoms in toxic models of Parkinson’s disease in the rat.

Isolongifolene mitigates rotenone-induced dopamine depletion and motor deficits through anti-oxidative and anti-apoptotic effects in a rat model of Parkinson's disease

Isolongifolene (ILF), a novel tricyclic sesquiterpene compound isolated from the Indian herb Murraya koenigii (M. koenigii), has been previously demonstrated to have a neuroprotective effect against rotenone-induced oxidative stress, mitochondrial dysfunction, and apoptosis in in vitro model. However, these neuroprotective and anti-apoptotic effects of ILF are not well understood and must be further investigated to elucidate the underlying molecular mechanism of ILF in animal experiments. The objective of this study was to evaluate the neuroprotective effect of ILF on motor impediments, neurochemical variables, anti-oxidative indices, and apoptotic protein expression in a rotenone-induced rat model of Parkinson's disease (PD). PD was induced in male albino Wistar rats via injection of 2.5 mg/kg rotenone for 4 weeks. Rotenone produces PD-like effects by promoting mitochondrial complex I inhibition and microglial activation properties. The protective effect of three different doses of ILF 5, 10 and 20 mg/kg were evaluated for spontaneous locomotion, rotarod performance, and striatal dopamine (DA) content. The results showed that ILF dose-dependently ameliorated the rotenone-induced striatal DA loss and motor impairment from 10 mg/kg. Therefore, we selected 10 mg/kg as the ILF dose for further investigation. Chronic administration of rotenone caused PD-related pathological processes like oxidative stress, and produced a significant decrease in tyrosine hydroxylase (TH), DA transporter (DAT), Vesicular monoamine transporter 2 (VMAT2), and a significant upregulated in α-synuclein and apoptotic protein expression of Bax, Cyt-C and caspases -3, -8 and −9 as well as by decreasing Bcl2 expression. Treatment with ILF 10 mg/kg mitigated oxidative stress in rotenone-treated rats. Furthermore, ILF dramatically alleviated rotenone-induced toxicity and cell death by increasing TH, DAT and VMAT2 expression and reducing the upregulation of α-synuclein, Bax, Cyt-C, caspases -3, -8 and -9. Together, our results confirm that ILF’s protective effect against rotenone-induced PD is mediated through anti-oxidant and anti-apoptotic properties. However, further in-depth investigations on ILF’s anti-inflammatory and mitochondrial protective abilities are needed to establish ILF as a potential drug candidate for the treatment of Parkinson’s disease.

P08-Diffusion kurtosis imaging detects early microstructural changes in dorsal motor nucleus of vagus in intragastric rotenone mouse model of Parkinson’s disease

The aim was to determine whether diffusion kurtosis imaging (DKI-MRI) could detect changes in dorsal motor nucleus of vagus (DMV) in mice who received chronic administration of rotenone. This may help in early diagnosis of patients with Parkinson’s disease. Mice received vehicle (VEH) or rotenone (ROT) intragastrically for 4 months. DKI scanning was performed at 2, 3 and 4 months. ROI analysis was used to compare kurtosis and diffusivity parameters in GM regions. WM tracts were investigated using the tract-based spatial statistics. We found significant increase in mean kurtosis in DMV in the ROT group at 2 months. At 3 months we found increase in kurtosis and decrease in diffusivity in almost all regions of interest, showing once the pathology crosses the DMV it spreads throughout the brain. At 4 months all the changes vanished. ROT group showed significant motor impairment at 4 months. At 2 months the DKI parameters may improve the early diagnosis of PD by showing increase in mean kurtosis in the DMV. This may help in monitoring and developing neuroprotective therapy. On the other hand, the lack of the DKI signal changes between ROT and VEH groups at the 4 months probably reflects the brain atrophy.

Neuroprotective effect of curcumin as evinced by abrogation of rotenone-induced motor deficits, oxidative and mitochondrial dysfunctions in mouse model of Parkinson's disease

Curcumin, a natural polyphenolic compound extracted from rhizomes of Curcuma longa (turmeric), a plant in the ginger family (Zingiberaceae) has been used worldwide and extensively in Southeast Asia. Curcumin exhibited numerous biological and pharmacological activities including potent antioxidant, cardiovascular disease, anticancer, anti-inflammatory effects and neurodegenerative disorders in cell cultures and animal models. Hence, the present study was designed in order to explore the possible neuroprotective role of curcumin against rotenone induced cognitive impairment, oxidative and mitochondrial dysfunction in mice. Chronic administration of rotenone (1mg/kg i.p.) for a period of three weeks significantly impaired cognitive function (actophotometer, rotarod and open field test), oxidative defense (increased lipid peroxidation, nitrite concentration and decreased activity of superoxide dismutase, catalase and reduced glutathione level) and mitochondrial complex (II and III) enzymes activities as compared to normal control group. Three weeks of curcumin (50, 100 and 200mg/kg, p.o.) treatment significantly improved behavioral alterations, oxidative damage and mitochondrial enzyme complex activities as compared to negative control (rotenone treated) group. Curcumin treated mice also mitigated enhanced acetylcholine esterase enzyme level as compared to negative control group. We found that curcumin restored motor deficits and enhanced the activities of antioxidant enzymes suggesting its antioxidant potential in vivo. The findings of the present study conclude neuroprotective role of curcumin against rotenone induced Parkinson's in mice and offer strong justification for the therapeutic prospective of this compound in the management of PD.

Neuroprotective Properties of Standardized Extracts of Hypericum perforatum on Rotenone Model of Parkinson’s Disease

Hipericum perforatum is a well-known herbal for its antidepressant property. Recently, it has been shown to have nootropic effects against neurodegenerative disorders. The aim of the present study was to evaluate the protective role of chronic administration of two standardized extract of Hypericum perforatum SHP1 rich in hyperforin (6%) and SHP2 extract poor in hyperforin (0.2%) on the neurodegeneration induced by chronic administration of rotenone in rats. Quercetin in liposomes, one active constituent, was tested in the same experimental conditions. The animals received pretreatments with SHP1 (4 mg/Kg, ip), SHP2 (4 mg/Kg, ip) or quercetin liposomes (25 and 100 mg/kg, ip) 60 min before of rotenone injection (2.5 mg/kg) for 45 days. Pretreatment of the animals with SHP1 and SHP2 efficiently halted deleterious toxic effects of rotenone, revealing normalization of catalepsy in addition to amelioration of neurochemical parameters. Also, SHP1 reduced neuronal damage, diminishing substantia nigra dopaminergic cell death caused by the pesticide, indicating benefit of neuroprotective therapy. In general, the SHP1 was more active than SHP2. In addition, SHP1 inhibited the apoptotic cascade by decreasing Bax levels. The results presented here indicate that mainly hyperforin and quercetin, may be involved in the neuroprotective action of Hypericum standardized extracts. Combination of dietary antioxidants could provide better therapeutic advantage for the management of Parkinson, and possibly other neurodegenerative disorders. Therefore H. perforatum standardized extract enriched in hyperforin, could be a better alternative for depressed elderly patients with degenerative disorders exhibiting elevated oxidative stress status.

Effect of Cynodon dactylon on rotenone induced Parkinson’s disease

In the present study, the aqueous extract of Cynodon dactylon (AECD) Pers. (Graminae) was evaluated for anti-parkinson’s activity in rats. The anti-parkinson’s effect of AECD was studied against rotenone (2 mg/kg, s.c.) - induced parkinsons in rats. In this study, chronic administration of rotenone in rats (28 days) produced motor dysfunctions like catalepsy and muscle rigidity along with a reduction in locomotor activity. Rotenone administration was also found to generate oxidative stress in the brain as evident from an increase in the level of TBARS and decrease in the levels of SOD and GSH. Pretreatment with AECD resulted in a significant (p < 0.001) decrease in catalepsy and muscle rigidity along with a significant (p < 0.001) increase in locomotion as compared to the rotenone-treated control group. AECD treated rats also showed a reduction in the TBARS level and an increase in the GSH, SOD and CAT levels; thus reducing the oxidative stress in the brain of animals. The study thus proved that Cynodon dactylon treatment significantly attenuated the motor defects and also protected the brain from oxidative stress, both induced by rotenone. These results strongly indicate the possible therapeutic potential of Cynodon dactylon as an antioxidant in Parkinson’s disease and other movement disorders.

The exceptional properties of 9‐methyl‐β‐carboline: stimulation, protection and regeneration of dopaminergic neurons coupled with anti‐inflammatory effects

Beta-carbolines (BCs) are potential endogenous and exogenous neurotoxins that may contribute to the pathogenesis of Parkinson's disease. However, we recently demonstrated protective and stimulatory effects of 9-methyl-BC (9-me-BC) in primary dopaminergic culture. In the present study, treatment with 9-me-BC unmasked a unique tetrad of effects. First, tyrosine hydroxylase (TH) expression was stimulated in pre-existing dopa decarboxylase immunoreactive neurons and several TH-relevant transcription factors (Gata2, Gata3, Creb1, Crebbp) were up-regulated. Neurite outgrowth of TH immunoreactive (THir) neurons was likewise stimulated. The interaction with tyrosine kinases (protein kinase A and C, epidermal growth factor-receptor, fibroblast growth factor-receptor and neural cell adhesion molecule) turned out to be decisive for these observed effects. Second, 9-me-BC protected in acute toxicity models THir neurons against lipopolysaccharide and 2,9-dime-BC(+) toxicity. Third, in a chronic toxicity model when cells were treated with 9-me-BC after chronic rotenone administration, a pronounced regeneration of THir neurons was observed. Fourth, 9-me-BC inhibited the proliferation of microglia induced by toxin treatment and installed an anti-inflammatory environment by decreasing the expression of inflammatory cytokines and receptors. Finally, 9-me-BC lowered the content of alpha-synuclein protein in the cultures. The presented results warrant the exploration of 9-me-BC as a novel potential anti-parkinsonian medication, as 9-me-BC interferes with several known pathogenic factors in Parkinson's disease as outlined above. Further investigations are currently under way.

Chronic administration of rotenone induces Parkinsonian symptoms and increases levels of nitric oxide in rat brain

Background Parkinson's disease (PD) is one of the most widespread neurodegenerative diseases. A reduction of complex I activity has been demonstrated in mitochondria of PD patients. Recently, it was shown that chronic subcutaneous exposure to low doses of rotenone (an inhibitor of mitochondrial NADH dehydrogenase and a commonly used pesticide) caused highly selective nigrostriatal dopaminergic lesions. However, while the behavioural effects of rotenone administration are well characterised, the mechanisms underlying rotenone action are unclear. Recent studies are regarding nitric oxide (NO) as universal neuronal messenger in the pathophysiology of neurodegenerative diseases. The aim of this work is to study mechanisms underlying oxidative damage of the various brain areas of rats produced by rotenone and to investigate a possible role of NO and lipid peroxidation (LPO) processes during chronic rotenone administration.

Activation of mitochondrial ATP-sensitive potassium channels improves rotenone-related motor and neurochemical alterations in rats

Our previous studies revealed that activation of mitochondrial ATP-sensitive potassium channels exerted protective effects on rotenone-treated rats and cultured cells. The aim of the present study is to examine the potential therapeutic effects of iptakalim, an ATP-sensitive potassium-channel opener, and diazoxide, a selective mitochondrial ATP-sensitive potassium-channel opener, on Parkinsonian symptoms in rats induced by rotenone. Rats were treated with rotenone (2.5 mg/kg s.c.) daily for 4 wk. This treatment caused a depletion of dopamine in the striatum and substantia nigra. Behaviourally, rotenone-infused rats exhibit Parkinsonian symptoms. Catalepsy was estimated by a 9-cm bar test. Treatment with L-dopa (10 mg/kg.d p.o.), iptakalim (0.75, 1.5, 3.0 mg/kg.d p.o.) and diazoxide (3.0 mg/kg.d p.o.) for 2 wk improved behavioural dysfunction and elevated dopamine contents in the striatum and substantia nigra of rotenone-treated rats. Studies also found that iptakalim and diazoxide could reduce the enzymic activities and mRNA levels of inducible nitric oxide synthase elicited by chronic administration of rotenone. All neurorestorative effects by both iptakalim and diazoxide were abolished by 5-hydroxydecanoate, a selective mitochondrial ATP-sensitive potassium-channel blocker. Collectively, the data suggested that mitochondrial ATP-sensitive potassium channels play a key role in improving both Parkinsonian symptoms and neurochemistry alterations of rotenone model rats, and selective activation of mitochondrial ATP-sensitive potassium channels may provide a new therapeutic strategy for treatment of early Parkinson's disease.

Sleep disturbances in the rotenone animal model of Parkinson disease

Parkinson disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc) and the presence of intracytoplasmatic inclusions known as Lewy bodies. Chronic administration of rotenone (RT) produces Parkinson's-like symptoms in rats. Because PD patients have disrupted sleep patterns, we determined if chronic RT administration produces similar changes in rat sleep. RT was administered for 28 days to rats. Basal and vehicle (VH) rats received saline or dimethyl sulfoxide and polyethylene glycol (1:1), respectively. VH infusion induced a progressive decrease in non-rapid eye movement sleep (NREMS) during the 4-week period of VH infusion and REMS was reduced in the third and fourth week of VH infusion. VH infusion did not induce dopaminergic cell degeneration. Rats receiving RT infusion also showed decreased NREMS during the treatment. REMS was dramatically reduced on day 7 although subsequently on days 13 and 20 REMS was similar to basal values. After 4 weeks of RT infusion, time in REMS was decreased again. In RT-treated rats, progressive dopaminergic cell degeneration occurred in the SNc. After 4 weeks of daily injections of l-dopa in RT-infused rats, NREMS values remained similar to those values obtained after RT alone. l-dopa therapy did, however, induce a recovery of REMS in weeks 3 and 4 of RT infusion. Dopaminergic cell damage persisted in the l-dopa-RT-infused rats. We conclude that the RT-PD rat model is associated with large long-term sleep disruption, however, the vehicle, DMSO/PEG had as large an effect as RT on sleep, thus changes in sleep cannot be ascribed to loss of dopaminergic cells. Such results question the validity of the RT-PD rat model.

Systematic administration of iptakalim, an ATP‐sensitive potassium channel opener, prevents rotenone‐induced motor and neurochemical alterations in rats

Our previous studies revealed that iptakalim, a novel ATP-sensitive potassium channel opener, has a significant neuroprotective function against ischemia in vivo or rotenone-induced neurotoxicity in vitro. To investigate the potential pharmaceutical benefit of ATP-sensitive potassium channel openers on neurodegenerative diseases, we studied the effects of iptakalim and diazoxide, a selective mitochondrial ATP-sensitive potassium channel opener, on the rotenone-induced nigrostriatal degeneration in rats. Iptakalim (1.5 mg/kg/day, orally) or diazoxide (1.5 mg/kg/day, orally) alone was administered to rats for 3 days, and then for 4 weeks was used daily with an injection of rotenone (2.5 mg/kg/day, subcutaneously) 1 hr later each time. The results showed that rotenone-infused rats exhibited parkinsonian symptoms and had dopamine depletion in the striatum and substantia nigra. Pretreatment with iptakalim or diazoxide prevented rotenone-induced catalepsy and the reduction of striatum dopamine contents. Moreover, iptakalim and diazoxide reduced the enzymatic activities and mRNA levels of inducible nitric oxide synthase elicited by chronic administration of rotenone. These neuroprotective effects of iptakalim and diazoxide were abolished by 5-hydroxydecanoate, a selective mitochondrial ATP-sensitive potassium channel blocker. In conclusion, our data suggested that mitochondrial ATP-sensitive potassium channels might play a key role in preventing both parkinsonian symptoms and neurochemistry alterations induced by rotenone in rats. The selective activation of mitochondrial ATP-sensitive potassium channels may provide a new therapeutic strategy for prevention and treatment of neurodegenerative disorders such as Parkinson's disease.

Behavioral and immunohistochemical effects of chronic intravenous and subcutaneous infusions of varying doses of rotenone

Mitochondrial toxins such as the complex 1 inhibitor rotenone are widely used as pesticides and may be present in military environments. Administration of rotenone can induce biochemical and histological alterations similar to those of Parkinson's disease in rats. However, only a subset of animals show these effects and it is unclear whether more subtle alterations are caused by chronic administration of rotenone in those animals that appear resistant to its toxic effects on dopaminergic nerve terminals. To address this question, vehicle or rotenone (2.0, 2.5, or 3.5 mg/kg/day) was administered intravenously or subcutaneously for 21 days to adult rats, and rotenone effects on survival, motor behavior, and striatal tyrosine hydroxylase immunoreactivity (TH-IR) were examined. Both intravenous and subcutaneous rotenone induced a dose-dependent decrease in survival rates. Surviving animals showed a decrease in spontaneous rearing. Locomotor activity and movement initiation time were also altered in some of the experimental groups. Confirming previous results, TH-IR in the striatum was markedly decreased in rats that fell ill early in the study and in a few of the surviving rats with high rotenone doses. However, none of the surviving rats receiving 2.0 mg/kg/day showed TH-IR loss reminiscent of Parkinson's disease, and loss of striatal TH-IR across doses was not correlated with motor behavior in individual rats. Thus, chronic administration of low doses of rotenone induces motor anomalies even in animals that do not develop histological signs of Parkinson's disease, indicating a pervasive neurological effect of moderate mitochondrial dysfunction in vivo.

Role of nitric oxide in rotenone-induced nigro-striatal injury.

Rotenone, a widely used pesticide, causes a syndrome in rats that mimics, both behaviorally and pathologically, the symptoms of Parkinson's disease. The present study evaluated the role of nitric oxide in rotenone-induced nigro-striatal injury. After administration of rotenone in rats for 40 days, there was a moderate but significant injury of the nigro-striatal pathway indicated by a 47% decrease in striatal dopamine levels and a 28% loss of substantia nigra tyrosine hydroxylase-immunopositive neurons. Furthermore, a significant (37%) increase in the number of cells positive for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) in the striatum was observed, accompanied by a 83% increase in nitric oxide synthase (NOS) activity and a significant increase in the production of 3-nitrotyrosine (3-NT). There was a significant increase (45%) in the optical density of NADPH-d staining and an increase (72%) in NOS activity in the substantia nigra. Moreover, administration of the neuronal NOS inhibitor 7-nitroindazole significantly attenuated the increased NOS activity and 3-NT production, and provided significant protection against rotenone-induced nigro-striatal injury. Our data suggest that chronic rotenone administration can lead to significant injury to the nigro-striatal system, mediated by increased generation of nitric oxide.