Peripheral Nervous System Research Articles

Myeloid gasdermin D drives early-stage T cell immunity and peripheral inflammation in a mouse model of Alzheimer's disease.

It is now realized that peripheral inflammation and abnormal immune responses, especially T cells, contribute to the development of Alzheimer's disease (AD). Gasdermin D (GSDMD) -mediated pyroptosis has been associated with several neuroinflammatory diseases, but whether GSDMD is involved in the peripheral inflammation and T cell immunity during AD remains unclear. We dynamically investigated GSDMD activation in the peripheral and central nervous system of 5×FAD mouse model and dissected the role of myeloid GSDMD using genetic knockout mice, especially its influence on peripheral T cell responses and AD inflammation. RNA sequencing and in vitro coculture were used to elucidate the underlying immune mechanisms involved. Targeted inhibitor experiments and clinical correlation analysis were used to further verify the function of GSDMD in AD. In the present study, caspase activated GSDMD in the spleen of 5×FAD mice earlier than in the brain during disease progression. Loss of myeloid cell GSDMD was shown to impair early-stage effector T cell activation in the periphery and prevent T cell infiltration into the brain, with an overall reduction in neuroinflammation. Furthermore, myeloid cell GSDMD induced T cell PD-1 expression through the IL-1β/NF-κB pathway, restricting regulatory T cells. The administration of a GSDMD inhibitor combined with an anti-PD-1 antibody was found to mitigate the development of AD-associated inflammation. In some AD patients, plasma sPD-1 is positively correlated with IL-Iβ and clinical features. Our study systematically identified a role for GSDMD in the AD-related peripheral inflammation and early-stage T cell immunity. These findings also suggest the therapeutic potential of targeting GSDMD for the early intervention in AD.

Monitoring Myelin Lipid Composition and the Structure of Myelinated Fibers Reveals a Maturation Delay in CMT1A.

Findings accumulated over time show that neurophysiological, neuropathological, and molecular alterations are present in CMT1A and support the dysmyelinating rather than demyelinating nature of this neuropathy. Moreover, uniform slowing of nerve conduction velocity is already manifest in CMT1A children and does not improve throughout their life. This evidence and our previous studies displaying aberrant myelin composition and structure in adult CMT1A rats prompt us to hypothesize a myelin and axon developmental defect in the CMT1A peripheral nervous system. Peripheral myelination begins during the early stages of development in mammals and, during this process, chemical and structural features of myelinated fibers (MFs) evolve towards a mature phenotype; deficiencies within this self-modulating circuit can cause its blockage. Therefore, to shed light on pathophysiological mechanisms that occur during development, and to investigate the relationship among axonal, myelin, and lipidome deficiencies in CMT1A, we extensively analyzed the evolution of both myelin lipid profile and MF structure in WT and CMT1A rats. Lipidomic analysis revealed a delayed maturation of CMT1A myelin already detectable at P10 characterized by a deprivation of sphingolipid species such as hexosylceramides and long-chain sphingomyelins, whose concentration physiologically increases in WT, and an increase in lipids typical of unspecialized plasma membranes, including phosphatidylcholines and phosphatidylethanolamines. Consistently, advanced morphometric analysis on more than 130,000 MFs revealed a delay in the evolution of CMT1A axon and myelin geometric parameters, appearing concomitantly with lipid impairment. We here demonstrate that, during normal development, MFs undergo a continuous maturation process in both chemical composition and physical structure, but these processes are delayed in CMT1A.

Trauma of the peripheral nervous system. Part 2. Conservative, interventional and surgical treatment

The main methods of surgical treatment of peripheral nervous system injuries are reviewed: neurolysis, epineural suture, autoneuroplasty, neurotization, tendon-muscle transposition, orthopedic interventions (arthrodesis, etc.), neurostimulator implantation and interventional interventions (radiofrequency neuroablation, cryoneurolysis).

Erythropoietin and glial cells in central and peripheral nervous systems.

Erythropoietin (EPO) is the main hematopoietic growth factor prescribed to overcome anemia. It is also a neuroprotective agent. EPO binds to the erythropoietin receptor (EPOR), expressed on neurons and glial cells in the central nervous system (CNS), and exerts its neuroprotective potencies through the EPO-EPOR complex. The mechanism of the signal transduction pathways of EPO on glial cells is defined. EPO-EPOR complex can affect neurological disorders, such as Alzheimer's disease, Parkinson's disease, ischemia, retinal injury, stroke, hypoxia, trauma, and demyelinating diseases, through acting downstream signaling pathways. This review focuses on the roles of EPO in different types of glial cells (astrocytes, microglia, oligodendrocytes, and Schwann cells) and their relationships with signaling pathways. Information on the non-erythropoietic action of EPO and related signaling systems in connection with glial cells could enhance EPO treatment to restore different CNS disorders and propose new perspectives on the neuroprotective potential of EPO.

The Peripheral Neuroimmune System.

Historically, the nervous and immune systems were studied as separate entities. The nervous system relays signals between the body and the brain by processing sensory inputs and executing motor outputs, whereas the immune system provides protection against injury and infection through inflammation. However, recent developments have demonstrated that these systems mount tightly integrated responses. In particular, the peripheral nervous system acts in concert with the immune system to control reflexes that maintain and restore homeostasis. Notwithstanding their homeostatic mechanisms, dysregulation of these neuroimmune interactions may underlie various pathological conditions. Understanding how these two distinct systems communicate is an emerging field of peripheral neuroimmunology that promises to reveal new insights into tissue physiology and identify novel targets to treat disease.

Comparative assessment of neurotrophic proteins in vibration disease

Introduction. The problem of health impairment due to the impact of physical factors, including vibration disease (VD), retains medical and social relevance due to the significant specific gravity in the structure of occupational morbidity and high prevalence. Under vibration exposure, the acid-base equilibrium, immune status are disturbed, rheological properties and properties of the neurohumoral system, as well as functional indices of the central and peripheral nervous system change. Neurotrophins are known to play an important role in regulating the development and functioning of the central and peripheral nervous systems. In this regard, research is needed to determine in VD patients the levels of neurospecific proteins, which may serve as one of the markers for tracing changes in the nervous system in workers. The aim of the study was to identify the peculiarities of changes in neurospecific proteins (BDNF, S100β, and MBP) in the serum of patients with VD of different genesis. Materials and methods. Serum concentrations of neurotrophic proteins: brain neurotrophic factor – BDNF, S100β protein and myelin basic protein (MBP) were studied by solid-phase enzyme-linked immunoassay. Results. There was an increase in serum BDNF, S100β protein, and MBP concentrations in persons with VD due to combined exposure to local and general vibration, and an increase in MBP was observed in patients with VD due to exposure to local vibration. Limitations. The limitations of this work are small groups of employees. Conclusion. As a result of studies, it can be assumed that in VD due to exposure to combined vibration, changes are observed in the peripheral and central parts of the nervous system, and in VD due to local vibration, disorders seem to be mainly associated with the peripheral nervous system. The general pattern of the revealed disorders in the content of MBP lies in the neurodestructive processes occurring in the nerve fibers in patients with VD, regardless of genesis. Summarizing the above mentioned, the validity of studying the concentration of neurospecific proteins in vibration disease occurring with damaging processes in the nervous tissue should be recognized.

Substance P a potent prognostic indicator for canine mammary tumours- a comparative study

Substance P, a neurotransmitter in the central and peripheral nervous system, is considered as a biomarker of pain due to its key role in nociception. But recent researches have proved the increased expression of Substance P and its receptors in human breast cancers and their role in its progression. Canine mammary glands and spontaneously occurring neoplasms in them are considered best models for human breast cancers. Hence as a preliminary study, the present research work was undertaken to assess the level of Substance P in dogs with mammary tumours in comparison to healthy dogs. From the dogs brought for ovariohysterectomy and mammary tumour resection, 20 female dogs were selected for the study. Signalment and detailed history regarding each dog were recorded. All the dogs were subjected to thorough preanaesthetic evaluation and were grouped into Group I (mammary tumour) and II (control group) with 10 dogs each. Blood was collected from all the dogs and serum was separated and stored at -20ºC for estimation of substance P. The same was performed using sandwich ELISA technique with canine specific Substance P ELISA kit. The values obtained for Group I and II were statistically analysed using independent t- test. The level of substance P was significantly higher in the dogs of Group I when compared to Group II Keywords: Substance P, mammary tumour, dogs

Cerebral vasculitis as clinical manifestation of neuroborreliosis: Pattern of vascular pathology and prognostic factors of outcome.

Neuroborreliosis is a tick-borne condition that affects the central and/or peripheral nervous system. Cerebral infarction associated with neuroborreliosis-related vasculitis has been reported in only a handful of cases. Therefore, specific patterns of vascular pathology and prognostic outcome factors are still incompletely understood. To determine the pattern of vascular pathology and prognostic outcome factors in patients with neuroborreliosis-related vasculitis. We performed a longitudinal multicenter study between 1997 and 2022 in five academic study sites in Germany with a cumulative reference area of 1,620,000 inhabitants. All patients diagnosed with neuroborreliosis-associated cerebral vasculitis were included. The evaluation of clinical parameters, including NIH Stroke Scale (NIHSS), disability ranking (modified Rankin Scale, mRS), and neuroimaging, was performed at admission as well as after 3 and 12 months. Linear regression analysis was used to identify the independent predictors of recurrent strokes, involvement of posterior circulation, or multiple vessels. Patients with neuroborreliosis-related vasculitis (n = 51) were relatively young (mean age: 62 years) and displayed a predominance of vascular events within the posterior circulation (60.8%). A history of smoking was linked to recurrent strokes/TIA (64.7% vs. 23.5%; p = 0.006), strokes in multiple territories (100% vs. 35.9%; p < 0.0001), and posterior circulation events (64.5% vs. 30.0%, p = 0.017), whereas other cardiovascular risk factors showed no significant differences. Linear regression analysis corroborated smoking's association with recurrent strokes/ transient ischemic attacks (B: 0.412; p = 0.002), multiple territory strokes/TIA (B: 0.467; p = 0.033), and posterior circulation events (B: 0.317; p = 0.033). A thorough CSF examination for neuroborreliosis is crucial, especially in younger stroke patients, particularly those experiencing posterior circulation ischemic events. Smoking cessation should be prompted in patients with neuroborreliosis-associated cerebral vasculitis.

Electrophysiological Changes in Median Nerve among Young Male Cigarette Smokers

Background: Cigarette smoking has been associated with numerous cardiovascular and respiratory disorders. Chronic smoking may also disrupt neuronal function and damage neurons in the peripheral nervous system. Median nerve conduction study is an important electrodiagnostic test for the detection of peripheral nerve dysfunction. Objectives: To observe the impact of cigarette smoking on the electrophysiological status of median motor and sensory nerves in apparently healthy male cigarette smokers. Materials and Methods: This case-control study was carried out in the Department of Physiology, Sir Salimullah Medical College, Dhaka, from July 2017 to June 2018 on thirty male cigarette smokers aged 25 to 40 years. For comparison, thirty age and BMI matched non-smoker healthy male subjects were selected as controls. Motor and sensory nerve conduction parameters (latency, amplitude and nerve conduction velocity) of right median nerve were evaluated by standard methods, using standard nerve conduction study and electromyography machines in the Department of Neurology, Dhaka Medical College Hospital. For statistical analysis, unpaired t test was performed. Results: In this study, median sensory nerve latency was significantly prolonged (p ˂ 0.001) and sensory nerve conduction velocity was significantly slower (p ˂ 0.001) in cigarette smokers. The mean amplitude was also slightly reduced in smokers, but statistically, it was insignificant. However, the distal latency of median motor nerve was slightly prolonged whereas, the amplitude and motor nerve conduction velocity were slightly reduced in cigarette smokers in comparison to those of non-smokers. But the differences were not statistically significant. In addition, 10% of cigarette smokers had subclinical impairment in median sensory nerve function. Conclusion: Chronic cigarette smoking induces significant electrophysiological changes in median sensory nerve fibers and causes sensory nerve dysfunction, while it does not markedly affect median motor nerve fibers in young individuals. KYAMC Journal Volume: 15, No: 01, April 2024: 03-07.

Progress in neurosurgical treatment of neurofibromatosis type 1

To summarize the latest developments in neurosurgical treatments for neurofibromatosis type 1 (NF1) and explore therapeutic strategies to provide comprehensive treatment guidelines for clinicians. The recent domestic and international literature and clinical cases in the field of NF1 were reviewed. The main types of neurological complications associated with NF1 and their treatments were thorough summarized and the future research directions in neurosurgery was analyzed. NF1 frequently results in complex and diverse lesions in the central and peripheral nervous systems, particularly low-grade gliomas in the brain and spinal canal and paraspinal neurofibromas. Treatment decisions should be made by a multidisciplinary team. Symptomatic plexiform neurofibromas and tumors with malignant imaging evidence require neurosurgical intervention. The goals of surgery include reducing tumor size, alleviating pain, and improving appearance. Postoperative functional rehabilitation exercises, long-term multidisciplinary follow-up, and psychosocial interventions are crucial for improving the quality of life for patients. Advanced imaging guidance systems and artificial intelligence technologies can help increase tumor resection rates and reduce recurrence. Neurosurgical intervention is the primary treatment for symptomatic plexiform neurofibromas and malignant peripheral nerve sheath tumors when medical treatment is ineffective and the lesions progress rapidly. Preoperative multidisciplinary assessment, intraoperative electrophysiological monitoring, and advanced surgical assistance devices significantly enhance surgical efficacy and safety. Future research should continue to explore new surgical techniques and improve postoperative management strategies to achieve more precise and personalized treatment for NF1 patients.

One Nervous System: Critical Links Between Central and Peripheral Nervous System Health and Implications for Obesity and Diabetes.

There are key differences between the central nervous system (CNS) (brain and spinal cord) and peripheral nervous system (PNS), such as glial cell types, whether there is protection by the blood-brain barrier, modes of synaptic connections, etc. However, there are many more similarities between these two arms of the nervous system, including neuronal structure and function, neuroimmune and neurovascular interactions, and, perhaps most essentially, the balance between neural plasticity (including processes like neuron survival, neurite outgrowth, synapse formation, gliogenesis) and neurodegeneration (neuronal death, peripheral neuropathies like axonopathy and demyelination). This article brings together current research evidence on shared mechanisms of nervous system health and disease between the CNS and PNS, particularly with metabolic diseases like obesity and diabetes. This evidence supports the claim that the two arms of the nervous system are critically linked and that previously understudied conditions of central neurodegeneration or peripheral neurodegeneration may actually be manifesting across the entire nervous system at the same time, through shared genetic and cellular mechanisms. This topic has been critically underexplored due to the research silos between studies of the brain and studies of peripheral nerves and an overemphasis on the brain in neuroscience as a field of study. There are likely shared and linked mechanisms for how neurons stay healthy versus undergo damage and disease among this one nervous system in the body—providing new opportunities for understanding neurological disease etiology and future development of neuroprotective therapeutics.

Voltage-clamp fluorometry for advancing mechanistic understanding of ion channel mechanisms with a focus on acid-sensing ion channels.

Voltage-clamp fluorometry (VCF) has revolutionized the study of ion channels by combining electrophysiology with fluorescence spectroscopy. VCF allows ion channel researchers to link dynamic structural changes, measured in real time, to function. Acid-sensing ion channels (ASICs) are Na+-permeable non-voltage-gated ion channels of the central and peripheral nervous system. They function as pH sensors, triggering neuronal excitation when pH decreases. Animal studies have shown the importance of ASICs for pain and fear sensation, learning, and neurodegeneration following ischaemic stroke. This review explores the technical bases and various developments of VCF, including fluorescence resonance energy transfer and the use of unnatural fluorescent amino acids. We provide an overview of VCF applications with a focus on ASICs, detailing how VCF has unveiled proton-induced conformational changes in key regions such as the acid pocket, wrist, and pore, crucial for understanding transitions between closed, open, and desensitized states.

SPROUTY2, a Negative Feedback Regulator of Receptor Tyrosine Kinase Signaling, Associated with Neurodevelopmental Disorders: Current Knowledge and Future Perspectives

Growth-factor-induced cell signaling plays a crucial role in development; however, negative regulation of this signaling pathway is important for sustaining homeostasis and preventing diseases. SPROUTY2 (SPRY2) is a potent negative regulator of receptor tyrosine kinase (RTK) signaling that binds to GRB2 during RTK activation and inhibits the GRB2-SOS complex, which inhibits RAS activation and attenuates the downstream RAS/ERK signaling cascade. SPRY was formerly discovered in Drosophila but was later discovered in higher eukaryotes and was found to be connected to many developmental abnormalities. In several experimental scenarios, increased SPRY2 protein levels have been observed to be involved in both peripheral and central nervous system neuronal regeneration and degeneration. SPRY2 is a desirable pharmaceutical target for improving intracellular signaling activity, particularly in the RAS/ERK pathway, in targeted cells because of its increased expression under pathological conditions. However, the role of SPRY2 in brain-derived neurotrophic factor (BDNF) signaling, a major signaling pathway involved in nervous system development, has not been well studied yet. Recent research using a variety of small-animal models suggests that SPRY2 has substantial therapeutic promise for treating a range of neurological conditions. This is explained by its function as an intracellular ERK signaling pathway inhibitor, which is connected to a variety of neuronal activities. By modifying this route, SPRY2 may open the door to novel therapeutic approaches for these difficult-to-treat illnesses. This review integrates an in-depth analysis of the structure of SPRY2, the role of its major interactive partners in RTK signaling cascades, and their possible mechanisms of action. Furthermore, this review highlights the possible role of SPRY2 in neurodevelopmental disorders, as well as its future therapeutic implications.

Infectious Neuropathies.

This review explores diverse infectious etiologies of peripheral nervous system (PNS) dysfunction, spanning sensory and motor neurons, nerves, and associated structures. Progress in viral and bacterial infections reveals multifaceted mechanisms underlying neuropathies, including viral neurotoxicity and immune-mediated responses. Latest diagnostic advances facilitate early PNS complication detection, with ongoing research offering promising treatment avenues. Emerging pathogens like severe acute respiratory syndrome coronavirus 2, Zika virus, and EV-D68 highlight the evolving infectious neuropathy paradigm. Recognizing characteristic patterns and integrating clinical factors are pivotal for precise diagnosis and tailored intervention. Challenges persist in assessment and management due to varied pathogenic mechanisms. Advancements in understanding pathogenesis have improved targeted therapies, yet gaps remain in effective treatments. Ongoing research is crucial for optimizing approaches and improving patient outcomes.

Limited evidence for anatomical contacts between intestinal GLP-1 cells and vagal neurons in male mice

The communication between intestinal Glucagon like peptide 1 (GLP-1)-producing cells and the peripheral nervous system has garnered renewed interest considering the availability of anti-obesity and anti-diabetic approaches targeting GLP-1 signaling. While it is well-established that intestinal GLP-1 cells can exert influence through paracrine mechanisms, recent evidence suggests the possible existence of synaptic-like connections between GLP-1 cells and peripheral neurons, including those of the vagus nerve. In this study, using a reporter Phox2b-Cre-Tomato mouse model and super-resolution confocal microscopy, we demonstrated that vagal axons made apparent contacts with less than 0.5% of GLP-1 cells. Moreover, immunohistochemistry combined with super-resolution confocal microscopy revealed abundant post-synaptic density 95 (PSD-95) immunoreactivity within the enteric plexus of the lower intestines of C57/BL6 mice, with virtually none in its mucosa. Lastly, utilizing RNAScope in situ hybridization in the lower intestines of mice, we observed that GLP-1 cells expressed generic markers of secretory cells such as Snap25 and Nefm, but neither synaptic markers such as Syn1 and Nrxn2, nor glutamatergic markers such as Slc17a7. Through theoretical considerations and a critical review of the literature, we concluded that intestinal GLP-1 cells primarily communicate with vagal neurons through paracrine mechanisms, rather than synaptic-like contacts.

In silico identification and virtual screening to discover potent therapeutic phytochemicals against CMT2A

Charcot-Marie-Tooth (CMT2A) neuropathies are a set of monogenic diseases that affect the peripheral nervous system. The pathogenesis of CMT2A, a disease caused by genetic mutations, is linked to impaired mitochondrial dynamics and axonal biology. Therapeutic options are still limited, with only a few drugs and other authorized or underdeveloped approaches. A ligand-based virtual screening methodology was used to identify the potential MFN promoters. The natural compound subset of the ZINC database (n = 559600) was obtained and filtered using a ligand-based virtual screening technique. The top 200 compounds were identified to have more than four features that matched the target compound. Pyrx software was used to analyze the molecular docking. Based on the number and type of important binding interactions and docking results, we selected top-20 compounds with the best binding affinities for the targeted protein. 3D-QSAR analyses were performed on potential ligands identified through molecular docking analyses to predict biological activity. The pEC50 and docking scores were used to identify the potential drugs. The ADMET analysis was used to assess the kinetic characteristics of the top two drugs. According to molecular dynamics simulation, the top compound ZINC000005313168 showed high conformational stability. Based on docking results and MD findings, the best in silico hits among the compounds investigated was ZINC000005313168. These findings suggest that the compound ZINC000005313168 could be used to treat CMT2A disease. Further in vivo and in vitro studies are required to consider the present analyses.

Lactobacillus rhamnosus ameliorates experimental autoimmune neuritis via modulation of gut microbiota and metabolites

BackgroundGuillain-Barre syndrome (GBS), an autoimmune disease of the peripheral nervous system, is hallmarked by demyelination and immune cellular infiltration. Experimental autoimmune neuritis (EAN), considered a GBS prototype model, has been studied for its potential therapeutic benefits from lactobacilli. This study evaluated the protective role of Lactobacillus rhamnosus GG (GG) for treatment in EAN. T cell ratio, inflammation factors, sciatic nerve pathology, intestinal permeability, and gut inflammation were assessed on day 19 post-immunization to evaluate GG's effect on EAN. Fecal metabolomics and 16s rRNA microbiome analysis were conducted to elucidate its mechanism. ResultsGG dynamically balanced CD4+/CD8+T cell ratio, reduced serum IL-1β and TNF-α expression, improved sciatic nerve demyelination and inflammation, and enhanced neurological scores during peak disease period. Intestinal mucosal damage was evident in EAN rats, with downregulated Occludin and ZO-1 and upregulated IL-1β, TNF-α, and Reg3γ. GG treatment restored intestinal mucosal integrity, upregulated Occludin and ZO-1, and downregulated IL-1, TNF-α, and Reg3γ. GG partially rectified the gut microbiota and metabolite imbalance in EAN rats. ConclusionGG mitigates EAN through immune response modulation and inflammation reduction via the gut microbiota and metabolites.

Unveiling the Role of Schwann Cell Plasticity in the Pathogenesis of Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is a prevalent complication of diabetes that affects a significant proportion of diabetic patients worldwide. Although the pathogenesis of DPN involves axonal atrophy and demyelination, the exact mechanisms remain elusive. Current research has predominantly focused on neuronal damage, overlooking the potential contributions of Schwann cells, which are the predominant glial cells in the peripheral nervous system. Schwann cells play a critical role in neurodevelopment, neurophysiology, and nerve regeneration. This review highlights the emerging understanding of the involvement of Schwann cells in DPN pathogenesis. This review explores the potential role of Schwann cell plasticity as an underlying cellular and molecular mechanism in the development of DPN. Understanding the interplay between Schwann cell plasticity and diabetes could reveal novel strategies for the treatment and management of DPN.

Implication of nutrition in severity of symptoms and treatments in quality of life in Parkinson's disease: a systematic review.

Therefore, this review aims to evaluate whether nutritional alterations are related either to the severity of motor and non-motor symptoms through the gut-brain axis or to the different treatments for PD and whether all of this, in turn, impacts the QoL of patients. A systematic review was carried out in MEDLINE and EMBASE databases, and Mendeley from 2000 to June 2024, searching for articles related to nutritional alterations in PD that alter patients' QoL. A total of 14 articles (2,187 participants) of 924 records were included. Among the 14 studies examined, two investigated the relationship between nutritional status and QoL in patients with PD. Poor nutritional status was associated with lower QoL scores. Four studies explored the connection between nutritional status and its impact on both motor and non-motor symptoms (psychiatric disturbances, cognitive impairment, and fatigue), revealing a link between nutritional status, activities of daily living, and the severity of motor symptoms. Three studies identified changes in body weight associated with the severity of symptoms related to mobility issues in PD patients. Three studies investigated the relationship between different PD treatments and their interaction with changes in weight and energy metabolism, highlighting that weight loss in the early stages of PD needs adequate monitoring of different treatments, as well as the interaction between the central and peripheral nervous systems in regulating these processes. Finally, two studies investigated how gastrointestinal alterations and changes in the microbiota were related to cognitive status, thus identifying them as risk factors and early signs of PD. The systematic review highlighted the significant relationship between nutritional status and QoL in patients with PD, as well as how the PD treatments influenced their weight. An association was also observed in the gut-brain axis, where adequate nutritional status influenced the balance of intestinal microbiota, slowing cognitive decline, improving activities of daily living, and the QoL of PD patients. It is confirmed that the nutritional status of patients influenced both motor and non-motor symptoms of the disease, and therefore their QoL.

Deciphering Peripheral Taste Neuron Diversity: Using Genetic Identity to Bridge Taste Bud Innervation Patterns and Functional Responses.

Peripheral taste neurons exhibit functional, genetic, and morphological diversity, yet understanding how or if these attributes combine into taste neuron types remains unclear. In this study, we used male and female mice to relate taste bud innervation patterns to the function of a subset of proenkephalin-expressing (Penk+) taste neurons. We found that taste arbors (the portion of the axon within the taste bud) stemming from Penk+ neurons displayed diverse branching patterns and lacked stereotypical endings. The range in complexity observed for individual taste arbors from Penk+ neurons mirrored the entire population, suggesting that taste arbor morphologies are not primarily regulated by neuron type. Notably, the distinguishing feature of arbors from Penk+ neurons was their propensity to come within 110 nm (in apposition with) different types of taste-transducing cells within the taste bud. This finding is contrary to the expectation of genetically defined taste neuron types that functionally represent a single stimulus. Consistently, further investigation of Penk+ neuron function revealed that they are more likely to respond to innately aversive stimuli -sour, bitter and high salt concentrations - as compared to the full taste population. Penk+ neurons are less likely to respond to non-aversive stimuli -sucrose, umami, and low salt- compared to the full population. Our data support the presence of a genetically defined neuron type in the geniculate ganglion that is responsive to innately aversive stimuli. This implies that genetic expression might categorize peripheral taste neurons into hedonic groups, rather than simply identifying neurons that respond to a single stimulus.Significance Statement Peripheral taste neuron coding has been heavily debated. Our study delves into this issue by leveraging genetic expression in a specific neuron subset to relate peripheral innervation patterns to functional taste responses. We examined a taste neuron type that appears to be in apposition with multiple taste-transducing cell types and responds to innately aversive concentrations of sour, bitter, and high NaCl stimuli. These collective observations suggest that genetic markers can delineate groups of neurons sharing similar hedonic responses rather than categorizing neurons solely based on individual taste qualities.