[Non-motor symptoms of Parkinson's disease from pathophysiology to early diagnosis]

Descriptive study of general practitioner's practices and knowledge about Parkinson's disease in the north of France

BACKGROUND

Parkinson's disease (PD), the second most frequent neurodegenerative disease, constitutes a major public health challenge. A guide published by the French National Authority for Health in 2012 and revised in 2016 put forward recommendations for general practitioners (GP) planning care pathways for parkinsonian patients. It is well known that PD can be difficult to diagnose, and that when patients consult their GP, symptoms are often still limited and embedded in clinical uncertainty. This means the pathway to confirmed diagnosis of PD can be lengthy and uncertain. Consequently, it is important to identify the difficulties GPs encounter when caring for PD patients in order to help them better close the gaps in care strategies.

METHODS

We conducted a descriptive cross-sectional survey in northern France to evaluate GP practices and knowledge about PD and their accordance with care pathway recommendations. The survey was conducted using a 30-item questionnaire sent to a sample of GPs.

RESULTS

There were 164 GPs who responded to the study questionnaire. The responding GPs generally followed current care pathway recommendations. In presence of a parkinsonian syndrome, 93.3% of the GPs reported systematically looking for an iatrogenic cause; 57.4% did not announce the diagnosis without the advice of a neurologist; 97.6% referred patients to a neurologist when they suspected PD; and 80.5% asked the neurologist to modify treatments. Our findings also revealed some difficult aspects of GP practices: only 2.5% had had additional training in neurology; only 53.6% felt comfortable with the diagnosis of PD; 63.6% prescribed additional exams for the diagnosis; most of the GPs were unaware of second-line treatments and their indications, and finally existence of PD expert centers was unknown for 85.2%.

CONCLUSIONS

These findings could be useful to guide implementation of new measures supporting more holistic care for PD patients; PD expert centers in France could provide complementary information and training for GPs.

Pathogenic Aspects and Therapeutic Avenues of Autophagy in Parkinson's Disease

The progressive aging of the population and the fact that Parkinson's disease currently does not have any curative treatment turn out to be essential issues in the following years, where research has to play a critical role in developing therapy. Understanding this neurodegenerative disorder keeps advancing, proving the discovery of new pathogenesis-related genes through genome-wide association analysis. Furthermore, the understanding of its close link with the disruption of autophagy mechanisms in the last few years permits the elaboration of new animal models mimicking, through multiple pathways, different aspects of autophagic dysregulation, with the presence of pathological hallmarks, in brain regions affected by Parkinson's disease. The synergic advances in these fields permit the elaboration of multiple therapeutic strategies for restoring autophagy activity. This review discusses the features of Parkinson's disease, the autophagy mechanisms and their involvement in pathogenesis, and the current methods to correct this cellular pathway, from the development of animal models to the potentially curative treatments in the preclinical and clinical phase studies, which are the hope for patients who do not currently have any curative treatment.

Mitochondrial Toxicant-Induced Neuronal Apoptosis in Parkinson's Disease: What We Know so Far

Parkinson's disease (PD) is one of the most common progressive neurodegenerative diseases caused by the loss of dopamine-producing neuronal cells in the region of substantia nigra pars compacta of the brain. During biological aging, neuronal cells slowly undergo degeneration, but the rate of cell death increases tremendously under some pathological conditions, leading to irreversible neurodegenerative diseases. By the time symptoms of PD usually appear, more than 50 to 60% of neuronal cells have already been destroyed. PD symptoms often start with tremors, followed by slow movement, stiffness, and postural imbalance. The etiology of PD is still unknown; however, besides genetics, several factors contribute to neurodegenerative disease, including exposure to pesticides, environmental chemicals, solvents, and heavy metals. Postmortem brain tissues of patients with PD show mitochondrial abnormalities, including dysfunction of the electron transport chain. Most chemicals present in our environment have been shown to target the mitochondria; remarkably, patients with PD show a mild deficiency in NADH dehydrogenase activity, signifying a possible link between PD and mitochondrial dysfunction. Inhibition of electron transport complexes generates free radicals that further attack the macromolecules leading to neuropathological conditions. Apart from that, oxidative stress also causes neuroinflammation-mediated neurodegeneration due to the activation of microglial cells. However, the mechanism that causes mitochondrial dysfunction, especially the electron transport chain, in the pathogenesis of PD remains unclear. This review discusses the recent updates and explains the possible mechanisms of mitochondrial toxicant-induced neuroinflammation and neurodegeneration in PD.

Gut dysfunction may be the source of pathological aggregation of alpha-synuclein in the central nervous system through Paraquat exposure in mice

BACKGROUND

One of the most common types of neurodegenerative diseases (NDDs) is Lewy body disease (LBD), which is characterized by excessive accumulation of α-synuclein (α-syn) in the neurons and affects around 6 million individuals globally. In recent years, due to the environmental factors that can affect the development of this condition, such as exposure to herbicides and pesticides, so it has become a younger disease. Currently, the vast majority of studies on the neurotoxic effects of paraquat (PQ) focus on the late mechanisms of neuronal-glial network regulation, and little is known about the early origins of this environmental factor leading to LBD.

OBJECTIVE

To observe the effect of PQ exposure on intestinal function and to explore the key components of communicating the gut-brain axis by establishing a mouse model.

METHODS AND RESULTS

In this study, C57BL/6J mice were treated by intraperitoneal injection of 15 mg/kg PQ to construct an LBD time-series model, and confirmed by neurobehavioral testing and pathological examination. After PQ exposure, on the one hand, we found that fecal particle counts and moisture content were abnormal. on the other hand, we found that the expression levels of colonic tight junction proteins decreased, the expression levels of inflammatory markers increased, and the diversity and abundance of gut microbiota altered. In addition, pathological aggregation of α-syn was consistent in the colon and midbrain, and the metabolism and utilization of short-chain fatty acids (SCFAs) were also markedly altered. This suggests that pathological α-syn and SCFAs form the gut may be key components of the communicating gut-brain axis.

CONCLUSION

In this PQ-induced mouse model, gut microbiota disruption, intestinal epithelial barrier damage, and inflammatory responses may be the main causes of gut dysfunction, and pathological α-syn and SCFAs in the gut may be key components of the communicating gut-brain axis.

Neuroprotective Effects of Oligosaccharides From Periplaneta Americana on Parkinson’s Disease Models In Vitro and In Vivo

Parkinson’s disease (PD) is one of the neurodegenerative diseases that is characterized by obvious motor and some nonmotor symptoms. Various therapeutics failed in the effective treatment of PD because of impaired neurological function in the brain and various complications. Periplaneta Americana oligosaccharides (OPA), the main active ingredients extracted from the medicine residues of Periplaneta Americana (P. Americana), have been reported to exert anti-inflammatory effects. The purpose of this study was to evaluate the possible mechanisms of OPA against 1-methyl-4-phenylpyridinium (MPP⁺)-induced apotosis in SH-SY5Y cells and its potential neuroprotective effects in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD subacute model mice. The data demonstrated that OPA significantly reversed the MPP⁺-induced decrease in SH-SY5Y cell viability, reduced the proportion of apoptotic cells, and protected SH-SY5Y cells from apoptosis in a dose-dependent manner by regulating the expression of apoptosis-related genes. Furthermore, OPA also alleviated the motor dysfunction of PD model mice, prevented the loss of tyrosine hydroxylase positive cells, suppressed the apoptosis of substantia nigra cells, and improved the dysbiosis of gut microbiota in vivo, suggesting that OPA demonstrated a significantly neuroprotective effect on PD model mice. These results indicated that OPA might be the possibility of PD therapeutics with economic utility and high safety.