Effects of compound rehmannia formula on dopamine transporter content in the corpus striatum of Parkinson's disease rats treated with levodopa

Long-term application of levodopa （L-3, 4-dihydroxyphenylalanine, L-DOPA） for Parkinson＇s disease can lead to adverse effects and reduce the amount of dopamine transporter （DAT） in the corpus striatum. The present study attempted to vedfy whether increasing the amount of DAT can reduce the adverse effects of L-DOPA. The specific radioactive uptake value of DAT in the corpus striatum of the lesioned hemisphere was significantly decreased, but was significantly increased following administration of compound rehmannia formula [Radix rehmanniae preparata （prepared rehmannia root）, Concha margantifera usta （nacre）, Radix paeoniae alba （white peony alba）, Radix salviae miltiotThizae （Danshen root）, Scorpio （scorpion）, green tea] for 4 weeks. The changes in DAT 1251-beta-carbomethoxy-3 beta-（4-iodophenyl） tropane autoradiography were consistent with those in radioactivity. The results revealed that the compound rehmannia formula can reduce the adverse effects of L-DOPA in treating Parkinson＇s disease, possibly by increasing the amount of DAT.

Effect of variable number of tandem repeats polymorphism in the human dopamine transporter gene on conflict information processing according to event-related potential

The dopamine transporter （DAT） is responsible for dopamine reuptake from the synaptic cleft. A variable number of tandem repeats polymorphism in the DAT gene is related to DAT availability and has been associated with cognition. With the advantage of high-time resolution, event-related potential is an important method to study the time course of human information processing. Previous results have suggested that dopamine exhibits a close relationship with conflicting information processing. Therefore, the present study assumed that conflicting information processing could be influenced by DAT variable number of tandem repeats polymorphism. To confirm this, the present study analyzed the influence of DAT genotypes on N270, which is presumed to reflect neural activity of conflict information processing in young healthy adults. A S1-S2 matching task was performed in healthy adults with 10/10 genotype （n = 14） and 10/9 genotypes （n = 14）, respectively, when event-related potentials were recorded. Results demonstrated that subjects with the 10/10 genotype exhibited shorter N270 latency and quicker reaction times compared with subjects with the 10/9 genotype. There were no differences in N270 amplitude between the two genotypes. These results suggested that 10/10 genotype subjects more efficiently processed conflict information.

Novel translational rat models of dopamine transporter deficiency

Dopamine （DA） is one of the brain＇s fundamental neurotransmitters. Despite the fact that the dopaminergic synapses constitute less than 1% of all brain synapses, DA is implicated in a number of critical physiological functions and in the pathogenesis of important psychiatric diseases such as schizophrenia, attention-deficit/hyperactivity disorder （ADHD）, Parkinson＇s disease （PD） and others.

PROPOFOL DECREASES ^(125)I-β-CIT BINDING TO THE DOPAMINE TRANSPORTER

Objective To determine the changes of brain dopamine transporter in mice receiving propofol anesthesia, 125I-β-CIT binding sites were observed at different time course. Methods 1. Twenty-seven normal Kunming mice were randomizedly divided into 3 groups (n = 9 ) and received intraperitoneal injection of propofol 100, 200 mg/kg and 10% intralipid (as control ) respetively. The time of losing righting reflex and displaying excitatory symptoms were recorded within 10min after administration. 2. Sixty Kunming mice were randomizedly assigned into 2 groups (n = 30 ). The mice were given 125I-β-CIT intravenously and propofol 200mg/kg or 10% intralipid (as control ) intraperitoneally. Five mice in every group were killed at different time course and their brain removed to isolate cerebellar, hypothalamus, striatum and cerebral cones. After weighting brain tissues, the radioactivity of 125I-β-CIT in different brain tissue was measured. Results 1. The time of losing righting reflex wes reduced from 319. 167 ± 88. 228s in proud 100mg/kg group to 231. 667 ± 46. 233s in propofol 200mg/kg group, and it fell from 193. 75 ± 27. 233s to 145. 556 ± 27. 437s for presenting excitatory activity. 2. Propofol intraperitoneal groups significantly decreed the combination of 125I-β-CIT and dopamine transporter in the striatum (P< 0. 01 ) and cerebral cortex (P < 0. 05) 120min after injection of propofol compared with the control group. But propofol increased the binding (P< 0. 05 ) in the striatum 30min after injection. theclusion The inhibitive effect of propofol on dopamine transporter to uptake dopamine in mice brain may contribute to some anesthetic mechanisms.

Dopamine in the prefrontal cortex plays multiple roles in the executive function of patients with Parkinson's disease

Parkinson’s disease can affect not only motor functions but also cognitive abilities,leading to cognitive impairment.One common issue in Parkinson’s disease with cognitive dysfunction is the difficulty in executive functioning.Executive functions help us plan,organize,and control our actions based on our goals.The brain area responsible for executive functions is called the prefrontal co rtex.It acts as the command center for the brain,especially when it comes to regulating executive functions.The role of the prefrontal cortex in cognitive processes is influenced by a chemical messenger called dopamine.However,little is known about how dopamine affects the cognitive functions of patients with Parkinson’s disease.In this article,the authors review the latest research on this topic.They start by looking at how the dopaminergic syste m,is alte red in Parkinson’s disease with executive dysfunction.Then,they explore how these changes in dopamine impact the synaptic structure,electrical activity,and connection components of the prefrontal cortex.The authors also summarize the relationship between Parkinson’s disease and dopamine-related cognitive issues.This information may offer valuable insights and directions for further research and improvement in the clinical treatment of cognitive impairment in Parkinson’s disease.

Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

Retinal dopamine transporter in experimental myopia

OBJECTIVE: To investigate the distribution, changes and a possible role for retinal dopamine transporter (DAT) in experimental myopia in chickens. METHODS: Two-day-old chickens were divided into four groups. Chicken eyes were fitted with lenses of -10D,-20D and translucent goggles unilaterally. Normal eyes were used as controls. After 3 wk, all chickens were given an intramuscular injection of (125)I-beta-CIT 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane and sacrificed two hours post injection. Retinal pigment epithelium (RPE) and the neural retina were obtained together or RPE was dissected out from the neural retina. Radioactive DAT from each specimen was assayed by gamma-counter. RESULTS: Retinal DAT was detected in RPE specimens rather than in the neural retina in all eyes. Radioactive DAT in myopic eyes was higher, compared with control eyes. CONCLUSIONS: Retinal DAT is mainly located in the RPE and may be involved in the formation of lens induced myopia (LIM) and form deprivation myopia (FDM). These methods may provide a new approach for further studying the role of the dopamine system in experimental myopia.

Single photon emission computer tomography of dopamine transporters in monkeys and humans with ^(99m)Tc-TRODAT-1

Background The diagnosis of Parkinson’s disease is presently based on non-specific symptoms. However, radionuclide dopamine transporters imaging can provide specific diagnostic tool for Parkinson’s disease. This study was designed to investigate the effects of imaging of dopamine transporters with 99mTc-TRODAT-1 in early diagnosis or differential diagnosis of Parkinson’s disease.Methods Nine normal monkeys were used to establish N-methyl-4-phenyl-1, 2, 3, 6-tetra-hydropyridine (MPTP) hemi-Parkinsonian animal models, and they were subjected to imaging. Twenty-nine patients with Parkinson’s disease, 12 age-matched healthy volunteers, and 18 age-matched patients with Parkinson’s syndrome were investigated. Single photon emission computer tomography (SPECT) was performed 3 hours after intravenous injection of 740 MBq 99mTc-TRODAT-1. Striatum specific uptake of 99mTc-TRODAT-1 was calculated according to the ratio of striatum (ST) to cerebellum (CB)in dopamine transporters uptake.Results In normal monkeys, bilateral ratio of ST/CB was 2.34±0.41. After the injection of MPTP, uptake rate of 99mTc-TRODAT-1 at damaged region was much lower than that at the contralateral region, resulting in a significant difference in the ratio of ST/CB (right: ST/CB=1.73±0.35; left: ST/CB=1.90±0.30), especially in hemi-Parkinsonian model monkeys (right: ST/CB=1.29±0.17; left: ST/CB=1.80±0.33). The ratios of ST/CB were 1.57±0.17 and 1.61±0.14 for the right and left respectively in the healthy volunteers, 1.04±0.29 and 1.06±0.30 in the age-matched patients with Parkinson’s disease, and 1.56±0.17 and 1.59±0.18 in the age-matched patients with Parkinson’s disease syndrome. A significant difference was noted between group of Parkinson’s disease, normal controls and Parkinson’s disease syndrome. Conclusion The results suggest that 99mTc-TRODAT-1 dopamine transporters SPECT has clinical application value in early diagnosis or differential diagnosis of Parkinson’s disease.

miR-137 and miR-491 Negatively Regulate Dopamine Transporter Expression and Function in Neural Cells

Abstract The dopamine transporter （DAT） is involved in the regulation of extracellular dopamine levels. A 40-bp variable-number tandem repeat （VNTR） polymorphism in the 3-untranslated region （3UTR） of the DAT has been reported to be associated with various phenotypes that are involved in the aberrant regulation of dopaminergic neu- rotransmission. In the present study, we found that miR- 137 and miR-491 caused a marked reduction of DAT expression, thereby influencing neuronal dopamine trans- port. Moreover, the regulation of miR-137 and miR-491 on this transport disappeared after the DAT was silenced. The miR-491 seed region that is located on the VNTR sequence in the 3＇UTR of the DAT and the regulatory effect of miR- 491 on the DAT depended on the VNTR copy-number. These data indicate that miR-137 and miR-491 regulate DAT expression and dopamine transport at the post- transcriptional level, suggesting that microRNA may be targeted for the treatment of diseases associated with DAT dysfunction.

Changes of dopamine transporter function in striatum during acute morphine addiction and its abstinence in rhesus monkey

Background Although dopamine transporter （DAT） is essential for addiction, the effect of additive drugs on DAT function is still controversial, especially for opiates. We investigated the functional changes of dopamine transporter in striatum of rhesus monkeys during acute morphine injection and its abstinence. Methods Four rhesus monkeys, 6 to 9 years old, two male and two female, were examined for 12 days. Single photon emission computed tomography （SPECT） was performed with ^99Tc^m-TRODAT-1 as the radiopharmaceutical dopamine transporter agent during different stages of acute morphine injection and its abstinence. The ratios of SPECT signal between striatum and cerebellum （ST/CB） were calculated. Results The ST/CB ratio declined significantly on the first day of morphine injection and continued declining with more morphine injections. After abstinence, the ratio increased with time, but was still significantly lower on the 5th day of abstinence than the normal level. Conclusions In rhesus monkey, acute morphine injection has both rapid and lasting effects on DAT by downregnlating its function. The decline was partially reversible following morphine abstinence. The results suggest that striatum is one effective target of morphine and that the DAT function in striatum is one indicator for morphine addiction.

Heterogeneity of Monosymptomatic Resting Tremor in a Prospective Study： Clinical Features, Electrophysiological Test, and Dopamine Transporter Positron Emission Tomography

Background： The relationship between monosymptomatic resting tremor （mRT） and Parkinson＇s disease （PD） Iemains controversial. In this study, we aimed to assess tile function ofpresynaptic dopaminergic neurons in patients with mRT by dopamine transporter positron emission tomography （DAT-PET） and to evaluate the utility of clinical features or electrophysioIogical studies in differential diagnosis. Methods： Thirty-three consecutive patients with toRT were enrolled prospectively. The Unified Parkinson＇s Disease Rating Scale and electromyography were tested before DAT-PET. Striatal asymmetry index （SAI） was calculated, and a normal DATPET was defined as a SAI of 〈15%. Scans without evidence of dopaminergic deficits （SWEDDs） were diagnosed in patients with a subsequent normal DAT-PET and structural magnetic resonance imaging. Results： Twenty-eight toRT patients with a significant reduction in uptake of DAT binding in the striatum were diagnosed with PD, while the remained 5 with a normal DAT-PET scan were SWEDDs. As for UPRDS, the dressing and hygiene score, walking m motor experiences of daily living （Part I1） and motor examination （Part Ill ） were significant different between two groups （P 〈 0.05 and P 〈 0.01, respectively）. Bilateral tremor was more frequent in the SWEDDs group （P 〈 0.05）. The frequency of resting tremor and the amplitude ofpostural tremor tend to be higher in the SWEDDs group （P = 0.08 and P= 0.05, respectively）. Conclusions： mRT is heterogeneous in presynaptic nigrostriatal dopaminergic degeneration, which can be determined by DAT-PET brain imaging. Clinical and electrophysiological features may provide clues to distinguish PD from SWEDDs.

Blunt dopamine transmission due to decreased GDNF in the PFC evokes cognitive impairment in Parkinson’s disease

Studies have found that the absence of glial cell line-derived neurotrophic factor may be the primary risk factor for Parkinson’s disease. However, there have not been any studies conducted on the potential relationship between glial cell line-derived neurotrophic factor and cognitive performance in Parkinson’s disease. We first performed a retrospective case-control study at the Affiliated Hospital of Xuzhou Medical University between September 2018 and January 2020 and found that a decreased serum level of glial cell line-derived neurotrophic factor was a risk factor for cognitive disorders in patients with Parkinson’s disease. We then established a mouse model of Parkinson’s disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and analyzed the potential relationships among glial cell line-derived neurotrophic factor in the prefrontal cortex, dopamine transmission, and cognitive function. Our results showed that decreased glial cell line-derived neurotrophic factor in the prefrontal cortex weakened dopamine release and transmission by upregulating the presynaptic membrane expression of the dopamine transporter, which led to the loss and primitivization of dendritic spines of pyramidal neurons and cognitive impairment. In addition, magnetic resonance imaging data showed that the long-term lack of glial cell line-derived neurotrophic factor reduced the connectivity between the prefrontal cortex and other brain regions, and exogenous glial cell line-derived neurotrophic factor significantly improved this connectivity. These findings suggested that decreased glial cell line-derived neurotrophic factor in the prefrontal cortex leads to neuroplastic degeneration at the level of synaptic connections and circuits, which results in cognitive impairment in patients with Parkinson’s disease.

Additive neurorestorative effects of exercise and docosahexaenoic acid intake in a mouse model of Parkinson’s disease

There is a need to develop interventions to slow or reverse the degeneration of dopamine neurons in Parkinson’s disease after diagnosis.Given that preclinical and clinical studies suggest benefits of dietary n-3 polyunsaturated fatty acids,such as docosahexaenoic acid,and exercise in Parkinson’s disease,we investigated whether both could synergistically interact to induce recovery of the dopaminergic pathway.First,mice received a unilateral stereotactic injection of 6-hydroxydopamine into the striatum to establish an animal model of nigrostriatal denervation.Four weeks after lesion,animals were fed a docosahexaenoic acid-enriched or a control diet for the next 8 weeks.During this period,the animals had access to a running wheel,which they could use or not.Docosahexaenoic acid treatment,voluntary exercise,or the combination of both had no effect on(i)distance traveled in the open field test,(ii)the percentage of contraversive rotations in the apomorphine-induction test or(iii)the number of tyrosine-hydroxylase-positive cells in the substantia nigra pars compacta.However,the docosahexaenoic acid diet increased the number of tyrosine-hydroxylase-positive terminals and induced a rise in dopamine concentrations in the lesioned striatum.Compared to docosahexaenoic acid treatment or exercise alone,the combination of docosahexaenoic acid and exercise(i)improved forelimb balance in the stepping test,(ii)decreased the striatal DOPAC/dopamine ratio and(iii)led to increased dopamine transporter levels in the lesioned striatum.The present results suggest that the combination of exercise and docosahexaenoic acid may act synergistically in the striatum of mice with a unilateral lesion of the dopaminergic system and provide support for clinical trials combining nutrition and physical exercise in the treatment of Parkinson’s disease.

Degree of dopaminergic degeneration measured by ^(99m)Tc-TRODAT-1 SPECT/CT imaging

To prevent and treat Parkinson＇s disease in its early stages,it is essential to be able to detect the degree of early dopaminergic neuron degeneration.Dopamine transporters（DAT） in the striatum regulate synaptic dopamine levels,and striatal ^99mTc-TRODAT-1 single-photon emission computed tomography（-SPECT） imaging is a marker for presynaptic neuronal degeneration.However,the association between the degree of dopaminergic degeneration and in vivo ^99mTc-TRODAT-1 SPECT imaging is unknown.Therefore,this study investigated the association between the degree of 6-hydroxydopamine（6-OHDA）-induced dopaminergic degeneration and DAT imaging using^99mTc-TRODAT-1 SPECT in rats.Different degrees of nigrostriatal dopamine depletion were generated by injecting different doses of 6-OHDA（2,4,and 8 μg） into the right medial forebrain bundle.The degree of nigrostriatal dopaminergic neuron degeneration was assessed by rotational behavior and immunohistochemical staining.The results showed that striatal ^99mTc-TRODAT-1 binding was significantly diminished both in the ipsilateral and the contralateral sides in the 4 and 8 μg 6-OHDA groups,and that DAT ^99mTc-TRODAT-1 binding in the ipsilateral striatum showed a high correlation to apomorphine-induced rotations at 8 weeks post-lesion（r = –0.887,P 〈 0.01）.There were significant correlations between DAT ^99mTc-TRODAT-1 binding in the ipsilateral striatum and the amount of tyrosine hydroxylase immunoreactive neurons in the ipsilateral substantia nigra in the 2,4,and 8 μg 6-OHDA groups at 8 weeks post-lesion（r = 0.899,P 〈 0.01）.These findings indicate that striatal DAT imaging using ^99mTc-TRODAT-1 is a useful technique for evaluating the severity of dopaminergic degeneration.

Effects of levodopa on dopaminergic neurons and induced dyskinesia A radio-imaging study

BACKGROUND： Radio-imaging has been used in neurological diagnosis, in particular for extrapyramidal disease. Moreover, it has been extensively utilized for early diagnosis of Parkinson＇s disease （PD） patients and in animal studies. However, it has rarely been utilized to assess drug-induced side effects in PD. OBJECTIVE： To investigate changes in dopamine transporter expression in a rat model of PD through the use of radio-imaging taking ^99mTc-TRODAT-1 as an imaging agent, and to explore the effect of levodopa （L-dopa） on dopaminergic neurons and the possible mechanisms of dyskinesia induction. DESIGN, TIME AND SETTING： A randomized, controlled, animal study was performed at the Laboratory of Department of Nuclear Medicine, Soochow University from April 2006 to June 2007. MATERIALS： 6-hydroxydopamine was purchased from Sigma, USA and L-dopa was purchased from Shanghai Fuda Pharmaceutical, China. ^99mTcO4-fresh elutriant was provided by the Department of Nuclear Medicine, First Hospital Affiliated to Soochow University. TRODAT-1 image kit was provided by Jiangsu Atomic Energy Research Establishment, China. The SN-695B radioimmunoassay gamma counter was purchased from Shanghai Hesuo Rihuan Photoelectric Instrument, China. The AZ-CA256eZ-Scope portable y camera was purchased from Anzai Medical, Japan. METHODS： A total of 34 healthy, male, Sprague Dawley rats were selected. Thirty were used to establish a PD model by injecting 6-hydroxydopamine into the right medial forebrain bundle, and four were injected with normal saline and served as the sham-surgery group. At the end of 4 weeks, 21 successful PD models were selected and randomly assigned to the L-dopa （n = 15, 20 mg/kg per day）, model （n = 6, normal saline）, and sham-surgery （n = 4, no treatment） groups. After 1 month of treatment, involuntary movement was evaluated twice weekly in each rat. A total of 0.2 mL ^99mTc-TRODAT-1 was injected into the tail vein 2 days following drug termination, and images of dopamine transporters were acquired 2 hours later. The rats were sacrificed and the ratios of specific radioactivity uptake were calculated. MAIN OUTCOME MEASURES： Manifestations of abnormal involuntary movement （AIM） were observed and total AIM scores were calculated. Images of dopamine transporters were acquired using an eZ-Scope portable y camera, and radioactive y quantification of ^99mTC-TRODAT-1 in the rat brains was assayed. The ratios of the left and right corpora striata were determined. The number and function of dopamine transporters was evaluated according to specific radioactivity uptake ratio （R） from the left and right corpora striata. RESULTS： Of 15 PD rats, nine exhibited AIM following L-dopa treatment： five scored 〉 20, i.e., severe grade, four scored 8-16, mild grade, and the remaining exhibited normal behavior. There were no differences in specific radioactivity uptake of dopamine transporter between the left and right corpora striata in the sham-surgery rats, and the images were clear and symmetrically distributed. Specific radioactivity uptake of the normal side （left） was significantly greater than the lesioned side （right） in the model group rats （P 〈 0.01）, and the R value was significantly increased compared with the sham-surgery group （P 〈 0.01）. The radio-ligand accumulation in the right corpus striatum was sparse. In the L-dopa group, specific radioactivity uptake was significantly decreased in the lesioned （right） side of the AiM rats, and the Rvalue was increased compared with the model group （P 〈 0.05）. The amount of radio-ligand in the right corpus striatum was diminished. The Rvalue was significantly reduced in the non-AIM rats compared with the AIM rats （P 〈 0.05）, and specific radioactivity uptake was significantly increased in the lesioned （right） side compared with the normal side （P 〈 0.05）. Moreover, radio-ligand accumulation was observed in the right corpus striatum, and differences in radio-ligand accumulation between the two sides were reduced. CONCLUSION： Following L-dopa treatment, the number and function of dopamine transporter in some PD rats were reduced. L-dopa was shown to be toxic to dopaminergic neurons and induced dyskinesia.

Single-nuclei RNA sequencing uncovers heterogenous transcriptional signatures in Parkinson's disease associated with nuclear receptor-related factor 1 defect

Previous studies have found that deficiency in nuclear receptor-related factor 1(Nurr1),which participates in the development,differentiation,survival,and degeneration of dopaminergic neurons,is associated with Parkinson s disease,but the mechanism of action is perplexing.Here,we first asce rtained the repercussion of knocking down Nurr1 by pe rforming liquid chromatography coupled with tandem mass spectrometry.We found that 231 genes were highly expressed in dopaminergic neurons with Nurr1 deficiency,14 of which were linked to the Parkinson’s disease pathway based on Kyoto Encyclopedia of Genes and Genomes analysis.To better understand how Nurr1 deficiency autonomously invokes the decline of dopaminergic neurons and elicits Parkinson’s disease symptoms,we performed single-nuclei RNA sequencing in a Nurr1 LV-shRNA mouse model.The results revealed cellular heterogeneity in the substantia nigra and a number of activated genes,the preponderance of which encode components of the major histocompatibility Ⅱ complex.Cd74,H2-Ab1,H2-Aα,H2-Eb1,Lyz2,Mrc1,Slc6α3,Slc47α1,Ms4α4b,and Ptprc2 were the top 10 diffe rentially expressed genes.Immunofluorescence staining showed that,after Nurr1knockdown,the number of CD74-immunoreactive cells in mouse brain tissue was markedly increased.In addition,Cd74 expression was increased in a mouse model of Parkinson’s disease induced by treatment with 6-hydroxydopamine.Ta ken togethe r,our res ults suggest that Nurr1 deficiency results in an increase in Cd74 expression,thereby leading to the destruction of dopaminergic neuro ns.These findings provide a potential therapeutic target for the treatment of Parkinson’s disease.

Catalytic Metalloporphyrin Protects Against Paraquat Neurotoxicity in vivo

Objective To examine the neuroprotective effects of a novel manganese porphyrin, manganese （Ill） meso-tetrakis （N,N＇-diethylimidazolium-2-yl） porphyrin （MnTDM）, in the mouse model of Parkinson＇s disease （PD） induced by paraquat （PQ）. Methods Male C57BL / 6 mice were subcutaneously injected with either saline or PQ at 2-day intervals for a total of 10 doses, MnTDM was subcutaneously injected with the PQ 2 h before treatment. Performance on the pole and swim test were measured 7 days after the last injection and animals were sacrificed one day later. Levels of dopamine （DA） and its metabolites in the striatum were measured by high-performance liquid chromatography with an electrochemical detector （HPLC-ECD）. Thiobarbituric acid （TBA） method was used to assay the lipid peroxidation product, malondialdehyde （MDA）, and the number of tyrosine hydroxylase （TH） positive neurons was estimated using immunohistochemistry. Results Pretreatment with MnTI）M significantly attenuated PQ-impaired behavioral performance, depleted dopamine content in striata, increased MDA, and dopaminergic neuron loss in the substantia nigra. Conclusions Oxidative stress plays an important role in PQ-induced neurotoxicity which can be potentially prevented by manganese porphyrin. These findings also propose a possible therapeutical strategy for neurodegenerative disorders associated with oxidative stress such as PD.

On the role of endogenous neurotoxins and neuroprotection in Parkinson's disease

For 50 years ago was introduced L-3,4-dihydroxyphenylalanine（L-dopa） in Parkinson＇s disease treatment and during this significant advances has been done but what trigger the degeneration of the nigrostriatal system remain unknown. There is a general agreement in the scientific community that mitochondrial dysfunction, protein degradation dysfunction, alpha-synuclein aggregation to neurotoxic oligomers, neuroinflammation, oxidative and endoplasmic reticulum stress are involved in the loss of dopaminergic neurons containing neuromelanin in Parkinson＇s disease. The question is what triggers these mechanisms. The age of normal onset in idiopathic Parkinson＇s disease suggests that environmental factors such as metals, pollutants or genetic mutations cannot be involved because these factors are related to early onset of Parkinsonism. Therefore, we have to search for endogenous neurotoxins and neuroprotection in order to understand what trigger the loss of dopaminergic neurons. One important feature of Parkinson＇s disease is the rate of the degenerative process before the motor symptoms are evident and during the disease progression. The extremely slow rate of Parkinson＇s disease suggests that the neurotoxins and the neuroprotection have to be related to dopamine metabolism. Possible candidates for endogenous neurotoxins are alpha-synuclein neurotoxic oligomers, 4-dihydroxyphenylacetaldehyde and ortho-quinones formed during dopamine oxidation to neuromelanin. Vesicular monoamine transporter-2, DT-diaphorase and glutathione transferase M2-2 seems to be the most important neuroprotective mechanism to prevent neurotoxic mechanism during dopamine oxidation.

Abuse-related effects of synthetic cathinones：importance of DAT/SERT relationships

OBJECTIVE Wide spread abuse of synthetic cathinones found in bath salts preparations has resulted in regulation of some cathinones internationally.Chemists skirt these laws by altering the chemical structures of first-generation cathinones(ie,MDPV,methylone,and mephedrone),resulting in second-generation cathinones(eg,α-PVP,α-PPP,MDPPP,and MDPBP).Although MDPV is a more effective reinforcer than cocaine,little is known about the reinforcing effectiveness of secondgeneration cathinones.To test the hypothesis that synthetic cathinones with higher selectivity for DAT relative to SERT are more effective reinforcers.METHODS Monoamine transporter inhibition was determined using synaptosomes prepared from rat brains.The relative reinforcing effectiveness of intravenously self-administered MDPV,MDPBP,MDPPP,α-PVP,α-PPP,and cocaine were directly compared through evaluations of (1)dose-response curves under a progressive ratio(PR)schedule of reinforcement and (2)demand curves obtained for each drug in male Sprague-Dawley rats.RESULTS Rank order selectivity for DAT/SERT wasα-PVP>MDPV>α-PPP≈MDPBP>MDPPP>cocaine.Comparisons of the maximum number of infusions obtained under a PR schedule of reinforcement(α-PVP>MDPV>α-PPP>MDPBP≈MDPPP>cocaine)and the essential value obtained for each drug in demand analyses(α-PVP>MDPV>α-PPP≈MDPBP≈MDPPP>cocaine)suggest relative reinforcing effectiveness is related to DAT/SERT selectivity.CONCLUSION These data provide evidence that DAT/SERT selectivity accounts for select synthetic cathinones functioning as more effective reinforcers than cocaine and may predict the abuse-related effects of novel synthetic cathinones in humans.

Dopaminergic Dysfunction and Glucose Metabolism Characteristics in Parkin-Induced Early-Onset Parkinson’s Disease Compared to Genetically Undetermined Early-Onset Parkinson’s Disease

While early-onset Parkinson’s disease(EOPD)caused by mutations in the parkin gene(PRKN)tends to have a relatively benign course compared to genetically undetermined(GU)-EOPD,the exact underlying mechanisms remain elusive.We aimed to search for the differences between PRKN-EOPD and GU-EOPD by dopamine transporter(DAT)and glucose metabolism positron-emission-tomography(PET)imaging.Twelve patients with PRKN-EOPD and 16 with GU-EOPD who accepted both ^(11)C-2b-carbomethoxy-3b-(4-trimethylstannylphenyl)tropane(^(11)C-CFT)and ^(18)F-fluorodeoxyglucose PET were enrolled.The ^(11)C-CFT uptake was analyzed on both regional and voxel levels,whereas glucose metabolism was assessed in a voxel-wise fashion.Correlations between DAT and glucose metabolism imaging,DAT imaging and clinical severity,as well as glucose metabolism imaging and clinical severity were explored.Both clinical symptoms and DAT-binding pat-terns in the posterior putamen were highly symmetrical in patients with PRKN-EOPD,and dopaminergic dysfunction in the ipsilateral putamen was severer in patients with PRKN-EOPD than GU-EOPD.Meanwhile,the DAT binding was associ-ated with the severity of motor dysfunction in patients with GU-EOPD only.Patients with PRKN-EOPD showed increased glucose metabolism in the contralateral medial frontal gyrus(supplementary motor area(SMA)),contralateral substantia nigra,contralateral thalamus,and contralateral cerebellum.Notably,glucose metabolic activity in the contralateral medial frontal gyrus was inversely associated with regional DAT binding in the bilateral putamen.Patients with PRKN-EOPD showed enhanced metabolic connectivity within the bilateral putamen,ipsilateral paracentral and precentral lobules,and the ipsilateral SMA.Collectively,compared to GU-EOPD,PRKN-EOPD is characterized by symmetrical,more severe dopaminergic dysfunction and relative increased glucose metabolism.Meanwhile,SMA with elevated glucose metabolism and enhanced connectivity may act as compensatory mechanisms in PRKN-EOPD.