Gastrointestinal Dysfunction and Neuropathologic Correlations in Parkinson Disease

Gut Epithelial Barrier Function is Impacted by Hyperglycemia and Secondary Bile Acids in Vitro: Possible Rescuing Effects of Specific Pectins

Gut epithelial barrier disruption is commonly observed in Western diseases like diabetes and inflammatory bowel disease (IBD). Enhanced epithelial permeability triggers inflammatory responses and gut microbiota dysbiosis. Reduced bacterial diversity in IBD affects gut microbiota metabolism, altering microbial products such as secondary bile acids (BAs), which potentially play a role in gut barrier regulation and immunity. Dietary fibers such as pectin may substitute effects of these BAs. The study examines transepithelial electrical resistance of gut epithelial T84 cells and the gene expression of tight junctions after exposure to (un)sulfated secondary BAs. This is compared to the impact of the dietary fiber pectin with different degrees of methylation (DM) and blockiness (DB), with disruption induced by calcium ionophore A23187 under both normal and hyperglycemic conditions. Unsulfated lithocholic acid (LCA) and deoxycholic acid (DCA) show a stronger rescuing effect, particularly evident under 20 mM glucose levels. DM19 with high DB (HB) and DM43HB pectin exhibit rescuing effects under both glucose conditions. Notably, DM19HB and DM43HB display higher rescue effects under 20 mM glucose compared to 5 mM glucose. The study demonstrates that specific pectins such as DM19HB and DM43HB may serve as alternatives for preventing barrier disruption in the case of disturbed DCA metabolism.

Correlation between 25-hydroxy-vitamin D and Parkinson's disease

Background

Previous cross-sectional studies have shown that Parkinson's disease (PD) patients have lower serum 25-hydroxyvitamin D (25(OH)D) concentrations than controls. Other studies have not yet tested whether research findings from other regions are generalizable to Chinese populations. In this case-control study, we examined the correlation between 25-hydroxyvitamin D and Parkinson's disease.

Methods

We established an association between 25-hydroxyvitamin D deficiency and PD in a case-control study of 100 PD patients and 100 control subjects free of neurological disease at the First Affiliated Hospital of Xinjiang Medical University.

Results

Total 25-hydroxyvitamin D levels were deficient in 21 % of patients with PD compared with 4 % of controls. In univariate analyses, plasma levels of 25-hydroxyvitamin D were associated with PD (p < 0.001). In multivariate analyses, vitamin D deficiency (25(OH)D < 20 ng/mL) was significantly associated with PD (p = 0.008, Odds Ratio =17.13, 95 % CI= 2.082-141.075). Individuals with 25(OH)D levels in the lowest quartile had the highest prevalence of PD (p = 0.026, OR=11.786, 95 % CI =1.342-103.51 compared to individuals with values in the highest quartile).

Conclusions

Our study reveals an association between 25-hydroxyvitamin D and PD. Patients with incident PD had significantly lower serum 25(OH)D concentrations than age-matched controls. High-risk PD patients with vitamin D deficiency who have not yet developed exercise impairment should undergo vitamin D measurement and any necessary treatment as soon as possible. Limitations of the study: the study needs further assessment of populations with low vitamin D levels in other regions of China; further assessment of the effect of different sources of vitamin D on PD; further study of longitudinal cohorts at different time points.

Management of Gastrointestinal Symptoms in Parkinson's Disease: A Comprehensive Review of Clinical Presentation, Workup, and Treatment

Gastrointestinal symptoms in Parkinson's disease (PD) are among the most prevalent and debilitating of complications and present unique diagnostic and management challenges. Patients with PD commonly experience dysphagia, nausea, bloating, and constipation related to pathologic involvement of the enteric nervous system. In turn, gastrointestinal complications may impact motor fluctuations and the efficacy of levodopa therapy. This review will explore the common gastrointestinal manifestations of PD with an emphasis on clinical presentation, workup, and treatment strategies.

Multidirectional associations between the gut microbiota and Parkinson's disease, updated information from the perspectives of humoral pathway, cellular immune pathway and neuronal pathway

The human gastrointestinal tract is inhabited by a diverse range of microorganisms, collectively known as the gut microbiota, which form a vast and complex ecosystem. It has been reported that the microbiota-gut-brain axis plays a crucial role in regulating host neuroprotective function. Studies have shown that patients with Parkinson's disease (PD) have dysbiosis of the gut microbiota, and experiments involving germ-free mice and fecal microbiota transplantation from PD patients have revealed the pathogenic role of the gut microbiota in PD. Interventions targeting the gut microbiota in PD, including the use of prebiotics, probiotics, and fecal microbiota transplantation, have also shown efficacy in treating PD. However, the causal relationship between the gut microbiota and Parkinson's disease remains intricate. This study reviewed the association between the microbiota-gut-brain axis and PD from the perspectives of humoral pathway, cellular immune pathway and neuronal pathway. We found that the interactions among gut microbiota and PD are very complex, which should be "multidirectional", rather than conventionally regarded "bidirectional". To realize application of the gut microbiota-related mechanisms in the clinical setting, we propose several problems which should be addressed in the future study.

Intestinal histomorphological and molecular alterations in patients with Parkinson's disease

BACKGROUND AND PURPOSE

Changes in gut microbiota composition, enteric inflammation, impairments of the intestinal epithelial barrier and neuroplastic changes in the enteric nervous system have been reported in Parkinson's disease (PD) patients and could contribute to the onset of both neurological and gastrointestinal symptoms. However, their mutual interplay has rarely been investigated. This study evaluated, in an integrated manner, changes in faecal microbiota composition, morphofunctional alterations of colonic mucosal barrier and changes of inflammatory markers in blood and stools of PD patients.

METHODS

Nineteen PD patients and nineteen asymptomatic subjects were enrolled. Blood lipopolysaccharide binding protein (LBP, marker of altered intestinal permeability) and interleukin-1β (IL-1β) levels, as well as stool IL-1β and tumour necrosis factor (TNF) levels, were evaluated. Gut microbiota analysis was performed. Epithelial mucins, collagen fibres, claudin-1 and S100-positive glial cells as markers of an impairment of the intestinal barrier, mucosal remodelling and enteric glial activation were evaluated on colonic mucosal specimens collected during colonoscopy.

RESULTS

Faecal microbiota analysis revealed a significant difference in the α-diversity in PD patients compared to controls, while no differences were found in the β-diversity. Compared to controls, PD patients showed significant chenags in plasma LBP levels, as well as faecal TNF and IL-1β levels. The histological analysis showed a decrease in epithelial neutral mucins and claudin-1 expression and an increased expression of acidic mucins, collagen fibres and S100-positive glial cells.

CONCLUSIONS

Parkinson's disease patients are characterized by enteric inflammation and increased intestinal epithelial barrier permeability, as well as colonic mucosal barrier remodelling, associated with changes in gut microbiota composition.

An umbrella review of systematic reviews with meta-analysis on the role of vitamins in Parkinson's disease

INTRODUCTION

This umbrella review aimed to systematically review the available literature and assess the association of dietary intake or serum levels of different vitamins and the risk of PD, to help find out more efficient treatments for PD patients by replenishing the deficiency of vitamins.

METHODS

Pubmed/Medline, Scopus, Google Scholar and hand searching bibliographies of retrieved articles in duplicate, were used to detect all relevant meta-analyses investigating the relationship between vitamins and PD. After study selection, data were extracted from previously published meta-analyses and pooled by Review Manager version 5.4 and CMA software version 2.2.064 to achieve effect sizes. Level of statistical significance was set at P ≤ 0.05.

RESULTS

14 meta-analyses were included in the meta-review. Serum vitamin D and B12 levels were significantly lower in PD (SMD = -0.67 and SMD = -0.40 respectively). Homocysteine (Hcy) levels were significantly higher in PD patients (SMD = 1.26). Also the odds ratio for highest vs. lowest vitamin E intake was 0.73 which was significant. However, there was no significant difference between vitamin A, C and B6 intake or serum levels in PD vs. control groups.

CONCLUSION

Serum vitamin D and B12 levels were significantly lower in PD in comparison to healthy individuals, while Hcy level was significantly higher in PD patients. Also higher vitamin E intake was associated with significantly lower risk of development of PD in comparison to lower vitamin E intake. However, there was no significant difference between risk of PD and higher vitamin A, C and B6 intake or serum levels of folate.

Vagus nerve stimulation increases stomach-brain coupling via a vagal afferent pathway

BACKGROUND

Maintaining energy homeostasis is vital and supported by vagal signaling between digestive organs and the brain. Previous research has established a gastric network in the brain that is phase synchronized with the rhythm of the stomach, but tools to perturb its function were lacking.

OBJECTIVE

To evaluate whether stomach-brain coupling can be acutely increased by non-invasively stimulating vagal afferent projections to the brain.

METHODS

Using a single-blind randomized crossover design, we investigated the effect of acute right-sided transcutaneous auricular vagus nerve stimulation (taVNS) versus sham stimulation on stomach-brain coupling.

RESULTS

In line with preclinical research, taVNS increased stomach-brain coupling in the nucleus of the solitary tract (NTS) and the midbrain while boosting coupling across the brain. Crucially, in the cortex, taVNS-induced changes in coupling occurred primarily in transmodal regions and were associated with changes in hunger ratings as indicators of the subjective metabolic state.

CONCLUSIONS

taVNS increases stomach-brain coupling via an NTS-midbrain pathway that signals gut-induced reward, indicating that communication between the brain and the body is effectively modulated by vago-vagal signaling. Such insights may help us better understand the role of vagal afferents in orchestrating the recruitment of the gastric network which could pave the way for novel neuromodulatory treatments.

Constipation Management in Parkinson Disease

ABSTRACT

BACKGROUND: Constipation is the most frequently reported nonmotor gastrointestinal symptom of Parkinson disease and can precede motor symptoms by up to 20 years. The causes of constipation can be multifactorial, but the implications can lead to life-threatening complications. Early recognition of constipation can lead to better health outcomes and quality of life. MANAGEMENT CONSIDERATIONS: The combination of nonpharmacological management through screening tools, nursing assessment, and patient education as well as pharmacological management is considered best practice. IMPLICATIONS FOR PRACTICE: Nurses who are knowledgeable on the current treatment options for constipation in Parkinson disease will be better equipped as active multidisciplinary team players to provide optimal care to their patients and achieve the best health outcomes.

Dysregulation of epithelial ion transport and neurochemical changes in the colon of a parkinsonian primate

The pathological changes underlying gastrointestinal (GI) dysfunction in Parkinson’s disease (PD) are poorly understood and the symptoms remain inadequately treated. In this study we compared the functional and neurochemical changes in the enteric nervous system in the colon of adult, L-DOPA-responsive, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated common marmoset, with naïve controls. Measurement of mucosal vectorial ion transport, spontaneous longitudinal smooth muscle activity and immunohistochemical assessment of intrinsic innervation were each performed in discrete colonic regions of naïve and MPTP-treated marmosets. The basal short circuit current (I_sc) was lower in MPTP-treated colonic mucosa while mucosal resistance was unchanged. There was no difference in basal cholinergic tone, however, there was an increased excitatory cholinergic response in MPTP-treated tissues when NOS was blocked with L-Nω-nitroarginine. The amplitude and frequency of spontaneous contractions in longitudinal smooth muscle as well as carbachol-evoked post-junctional contractile responses were unaltered, despite a decrease in choline acetyltransferase and an increase in the vasoactive intestinal polypeptide neuron numbers per ganglion in the proximal colon. There was a low-level inflammation in the proximal but not the distal colon accompanied by a change in α-synuclein immunoreactivity. This study suggests that MPTP treatment produces long-term alterations in colonic mucosal function associated with amplified muscarinic mucosal activity but decreased cholinergic innervation in myenteric plexi and increased nitrergic enteric neurotransmission. This suggests that long-term changes in either central or peripheral dopaminergic neurotransmission may lead to adaptive changes in colonic function resulting in alterations in ion transport across mucosal epithelia that may result in GI dysfunction in PD.

The relationships of vitamin D, vitamin D receptor gene polymorphisms, and vitamin D supplementation with Parkinson's disease

In recent years, many studies have investigated the correlations between Parkinson's disease (PD) and vitamin D status, but the conclusion remains elusive. The present review focuses on the associations between PD and serum vitamin D levels by reviewing studies on the associations of PD with serum vitamin D levels and vitamin D receptor (VDR) gene polymorphisms from PubMed, Web of Science, Cochrane Library, and Embase databases. We found that PD patients have lower vitamin D levels than healthy controls and that the vitamin D concentrations are negatively correlated with PD risk and severity. Furthermore, higher vitamin D concentrations are linked to better cognitive function and mood in PD patients. Findings on the relationship between VDR gene polymorphisms and the risk of PD are inconsistent, but the FokI (C/T) polymorphism is significantly linked with PD. The occurrence of FokI (C/T) gene polymorphism may influence the risk, severity, and cognitive ability of PD patients, while also possibly influencing the effect of Vitamin D3 supplementation in PD patients. In view of the neuroprotective effects of vitamin D and the close association between vitamin D and dopaminergic neurotransmission, interventional prospective studies on vitamin D supplementation in PD patients should be conducted in the future.

Altered Gut Microbiome and Intestinal Pathology in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder arising from an interplay between genetic and environmental risk factors. Studies have suggested that the pathological hallmarks of intraneuronal α-synuclein aggregations may start from the olfactory bulb and the enteric nervous system of the gut and later propagate to the brain via the olfactory tract and the vagus nerve. This hypothesis correlates well with clinical symptoms, such as constipation, that may develop up to 20 years before the onset of PD motor symptoms. Recent interest in the gut-brain axis has led to vigorous research into the gastrointestinal pathology and gut microbiota changes in patients with PD. In this review, we provide current clinical and pathological evidence of gut involvement in PD by summarizing the changes in gut microbiota composition and gut inflammation associated with its pathogenesis.

Increased risk of appendectomy in patients with gastroesophageal reflux disease: A nested case-control study using a national sample cohort

The purpose of this study is to confirm and complement previous data regarding an association between gastroesophageal reflux disease and appendectomy.The Korean National Health Insurance Service-National Sample Cohort includes data from people ≥ 20 years old collected from 2002 to 2013. A total of 13,484 participants who received an appendectomy were matched with 53,936 controls at a 1:4 ratio. We analyzed the previous histories of gastroesophageal reflux disease (GERD) in the appendectomy and control groups. Appendectomies were identified using operation codes (Q2860-Q2863) exclusive for appendicitis (International Classification of Disease-10 (ICD-10): K35). GERD was defined using the ICD-10 (K21), and patients who were treated ≥ 2 times and were prescribed a proton pump inhibitor (PPI) for ≥ 2 weeks were included. Crude (simple) and adjusted odds ratios (ORs) for GERD and appendectomy were analyzed using conditional logistic regression analyses.A higher GERD rate was detected in the appendectomy group (11.4% [1,713/15,062]) than in the control group (8.2% [4,947/60,248], P < .001). Adjusted ORs for GERD were 1.37 (95% confidence interval [CI] = 1.30-1.45) (P < .001). Subgroup analyses stratified according to age and sex revealed consistent findings. The adjusted OR for GERD in participants prescribed PPIs for ≥ 30 days was 1.31 (95% CI = 1.20-1.43), and the adjusted OR for GERD in participants prescribed PPIs for ≥ 60 days was 1.30 (95% CI = 1.15-1.48).The Odds for GERD were higher in the appendectomy group than in the control group.

Association Between Serum Vitamin D Levels and Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Vitamin D is an important secosteroid which is involved the development and regulation of brain activity. Several studies have focused on exploring the relationship between serum vitamin D levels and Parkinson's disease (PD), but the conclusion remains ambiguous.

Methods: We searched observational studies that explored the association between serum vitamin D levels and PD based on PubMed, EMBASE and Cochrane library from inception through to January 2018. The quality of included studies was evaluated by using Newcastle-Ottawa Scale (NOS). Statistical analysis of this meta-analysis was performed by Stata version 12.0 and R software.

Results: Twenty studies with a total of 2,866 PD patients and 2,734 controls were included. Compared with controls, PD patients had lower serum vitamin D levels (WMD −3.96, 95%CI −5.00, −2.92), especially in higher latitude regions (WMD −4.20, 95%CI −5.66, −2.75). Assay methods contributed significantly to high heterogeneity. Furthermore, PD patients with deficient vitamin D levels had advanced risk (OR 2.08, 95%CI 1.35, 3.19) than those patients with insufficient ones (OR = 1.73, 95%CI 1.48, 2.03). In addition, serum vitamin D levels were also related to the severity of PD (WMD −5.27, 95%CI −8.14, −2.39) and the summary correlation coefficient showed strongly negative correlation (r = −0.55, 95%CI −0.73, −0.29). Moreover, the pooled correlation coefficient revealed that serum vitamin D levels were also negatively correlated to the Unified Parkinson's Disease Rating Scale III (UPDRS III) (r = −0.36, 95%CI −0.53, −0.16), but did not correlate with the duration of PD (P = 0.37) and age of patients (P = 0.49).

Conclusion: Serum vitamin D levels are inversely associated with the risk and severity of PD. Our results provided an updated evidence of association between low vitamin D levels and PD and prompt the adjunctive therapeutic decisions about vitamin D replacement in PD.

Gastrointestinal nervous system α-synuclein as a potential biomarker of Parkinson disease

Lewy bodies (LB) play an essential role in the development, survival, and function maintenance of midbrain dopaminergic (DA) neurons in Parkinson disease (PD). Alpha-synuclein (α-synuclein) is the major component of Lewy bodies and is a potential target for Parkinson's disease (PD) therapies. α-synuclein can be detected in the gastrointestinal (GI) nervous system, but whether there is any association between altered α-synuclein expression in the GI nervous system and the onset of PD is not known. The answer to this question presents the opportunity for a promising biomarker in the pre-clinical diagnosis of PD. As such, this study aimed to measure the α-synuclein level in the GI nervous system of Parkinson's disease patients.The protein levels of α-synuclein in the GI nervous system of 31 PD patients (PD group) and 32 patients without PD or Parkinsonism-plus syndrome (control group) were evaluated via immunohistochemical staining. The χ test was performed to evaluate the differences between the PD group and control group. In addition to the distribution of α-synuclein positive protein, regional distribution of the protein in the stomach was also evaluated across groups.Alpha synuclein overexpression was found in the GI nervous tissue of PD patients. The PD group included 17 positive results and 14 negative results. The control group exhibited 7 positive results and 24 negative results. The χ test showed that χ = 7.255, P = .01. The distribution of these positive cases in the gastrointestinal system, the χ test showed that P = .949. The 21 stomach tissues had 7 α-synuclein positive protein tissues, while the body of stomach (4 α-synuclein positive protein) was higher than in other regions.Aberrant expression of α-synuclein was detected in the GI tissues of PD patients, though the distribution of α-synuclein in the gastrointestinal tract had no specificity. Gastrointestinal mucous biopsy could be regarded as a potential opportunity for the early-stage diagnostic exploration of PD, through the detection of α-synuclein inclusions.

High Dietary Iron Supplement Induces the Nigrostriatal Dopaminergic Neurons Lesion in Transgenic Mice Expressing Mutant A53T Human Alpha-Synuclein

Both alpha-synuclein aggregation and iron deposits are neuropathological hallmarks of Parkinson’s disease (PD). We are particularly interested in whether iron could synergize with alpha-synuclein pathology in vivo, especially in the nigrostriatal system. In the present study, we reported transgenic mice with overexpressing human A53T alpha-synuclein, as well as WT mice with high dietary iron displayed hyperactive motor coordination and impaired colonic motility, compared with those with basal dietary iron. Only A53T mice, but not WT mice with high dietary iron exhibited nigral dopaminergic neuronal loss, lower levels of tyrosine hydroxylase (TH) in the substantia nigra (SN) and decreased dopamine contents in the striatum. Although there was no obvious elevation of iron contents in the SN in WT mice with high dietary iron, we observed iron contents in the SN were especially higher than the other brain regions in 12-month aged mice with either high or basal dietary iron. These results suggested high dietary iron supplement could induce nigral dopaminergic neurons lesion in A53T mice, which might be due to the vulnerability of SN to accumulate iron.

Genomic DNA levels of mutant alpha-synuclein correlate with non-motor symptoms in an A53T Parkinson's disease mouse model

Alpha-synuclein plays a key role in the pathogenesis of Parkinson's disease (PD). A robust transgenic mouse model has been generated that overexpresses the mutant human A53T alpha-synuclein under the mouse prion protein gene promoter; these mice develop age-dependent motor deficits. Recently, compared to wild-type (WT) littermates, A53T alpha-synuclein mice were reported to display non-motor symptom deficits, e.g., anxiety-like and depressive-like behaviors, odor discrimination and detection impairments, and gastrointestinal dysfunction, at 6 months of age or older. However, the differences between heterozygous and homozygous mice in terms of non-motor symptoms and whether the genomic DNA levels of alpha-synuclein correlate with the symptoms have not yet been elucidated. In the present work, we used littermate WT and heterozygous and homozygous A53T mice that were characterized by a modified genotyping protocol and observed a unilateral decline in the dopamine transporter (DAT) distribution from 3 months to 12 months of age in homozygous mice. We evaluated non-motor symptoms by measuring colon motility, anxiety-like and depressive-like behaviors, and motor coordination. The results showed that homozygous A53T mice exhibited earlier abnormal non-motor symptoms compared to their heterozygous littermates. The severity of impaired colon motility as well as anxiety-like and depressive-like behaviors were correlated with the genomic DNA levels of A53T mutant alpha-synuclein. More noticeable, motor coordination aberrances were also observed in homozygous A53T mice. This study provides direct evidence that the genomic DNA levels of mutant alpha-synuclein correlate with non-motor symptoms in an A53T mouse model, indicating that the genomic DNA levels of mutant alpha-synuclein should be tightly manipulated in PD model studies.

Neuropathology correlates of cognitive assessments

BACKGROUND

Alzheimer's disease and other dementias are the fourth largest contributors to neurological disability and the second largest contributor to deaths from neurological disease. Described in the 1980s as 'the silent epidemic' these disorders principally, though not exclusively, affect persons 80 years or older, and in developed countries, this 'old old' population continues to grow. Definitive diagnosis of the underlying cause of the neurodegenerative disease relies on neuropathological evaluation.` AIMS: Herein, we review the sampling methods, analysis and interpretation of both pathological and immunocytochemical techniques in the diagnostic assessment of neurodegenerative disease.

FINDINGS

Neurodegenerative disorders are characterised by accumulation of pathologically altered protein in the human brain, and in some cases, in the peripheral tissues. Whilst it is suggested that a comprehensive review of the patient's clinical history, cognition and behaviour, together with a full clinical examination and radiological analysis, should lead to a high degree of confidence in the clinical diagnosis, the view persists that underlying pathology can only be predicted on clinical grounds especially in Alzheimer's disease, vascular brain injury and diffuse Lewy body disease with only limited accuracy.

CONCLUSIONS

Neuropathological assessment of well characterised clinical cases provides accurate data on the prevalence of neurodegenerative diseases. This will aid future biomarker, neuroimaging studies and clinical trials focussed on population based cohorts.

Non-CNS pathogenic origin of Parkinson's disease

The gut with its variety of microbiota may serve as an etiological origin of diseases. Gut microbes may also play a role in the pathogenesis of diseases beyond their simple nutritional maintenance and support. For example, gut protein aggregation, possibly aided by microbes as well as nasal influences, might be linked to disease that may move to the brain through the vagus nerve. To this end, Braak has offered a "dual-hit" hypothesis that proposes a novel etiology for Parkinson's disease (PD). The hypothesis places the initial origin of the disease in the nose and the gastrointestinal tract (GI) after infection by an unknown pathogen that could aggregate in the gut and then eventually spread to the brain via the autonomic plexuses. Gut health functioning, therefore, may affect brain status and behavior. A protein known as alpha-synuclein accumulates in brains of people with Parkinson's disease that is also present in the GI before the onset of motor symptoms. Therefore, the stomach, previously thought to be a stable mechanism throughout life, might explain some etiological origins of disease. Finally, the vagus nerve of the autonomic system that extends from the brain to the abdomen and exercises both sympathetic and parasympathetic roles might be associated with PD diagnosis along with Lewy body influences.

Neuropathology of Nonmotor Symptoms of Parkinson's Disease

Parkinson's disease (PD), a multiorgan neurodegenerative disorder associated with α-synuclein deposits throughout the nervous system and many organs, is clinically characterized by motor and nonmotor features, many of the latter antedating motor dysfunctions by 20 or more years. The causes of the nonmotor manifestations such as olfactory, autonomic, sensory, neuropsychiatric, visuospatial, sleep, and other disorders are unlikely to be related to single lesions. They are mediated by the involvement of both dopaminergic and nondopaminergic systems, and diverse structures outside the nigrostriatal system that is mainly responsible for the motor features of PD. The nonmotor alterations appear in early/prodromal stages of the disease and its further progression, suggesting a topographical and chronological spread of the lesions. This lends further support for the notion that PD is a multiorgan proteinopathy, although the exact relationship between presymptomatic and later developing nonmotor features of PD and neuropathology awaits further elucidation.

Colonic Oxidative and Mitochondrial Function in Parkinson's Disease and Idiopathic REM Sleep Behavior Disorder

OBJECTIVE

To determine potential mitochondrial and oxidative alterations in colon biopsies from idiopathic REM sleep behavior disorder (iRBD) and Parkinson's disease (PD) subjects.

METHODS

Colonic biopsies from 7 iRBD subjects, 9 subjects with clinically diagnosed PD, and 9 healthy controls were homogenized in 5% w/v mannitol. Citrate synthase (CS) and complex I (CI) were analyzed spectrophotometrically. Oxidative damage was assessed either by lipid peroxidation, through malondialdehyde and hydroxyalkenal content by spectrophotometry, or through antioxidant enzyme levels of superoxide dismutase-2 (SOD2), glutathione peroxidase-1 (Gpx1), and catalase (CAT) by western blot. The presence of mitochondrial DNA (mtDNA) deletions was assessed by long PCR and electrophoresis.

RESULTS

Nonsignificant trends to CI decrease in both iRBD (45.69 ± 18.15; 23% decrease) and PD patients (37.57 ± 12.41; 37% decrease) were found compared to controls (59.51 ± 12.52, p: NS). Lipid peroxidation was maintained among groups (iRBD: 27.46 ± 3.04, PD: 37.2 ± 3.92, and controls: 31.71 ± 3.94; p: NS). Antioxidant enzymes SOD2 (iRBD: 2.30 ± 0.92, PD: 1.48 ± 0.39, and controls: 1.09 ± 0.318) and Gpx1 (iRBD 0.29 ± 0.12, PD: 0.56 ± 0.33, and controls: 0.38 ± 0.16) did not show significant differences between groups. CAT was only detected in 2 controls and 1 iRBD subject. One iRBD patient presented a single mtDNA deletion.