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Journal of Neurophysiology Aug 2023Spinal motoneurons contain many ion channels and receptors upon which various cannabinoids are known to act. This scoping review involved the synthesis of evidence from... (Review)
Review
Spinal motoneurons contain many ion channels and receptors upon which various cannabinoids are known to act. This scoping review involved the synthesis of evidence from literature published before August 2022 about the effects of cannabinoids on quantifiable measures of motoneuron output. Four databases (MEDLINE, Embase, PsycINFO, and Web of Science CoreCollection) were queried and 4,237 unique articles were retrieved. Twenty-three studies met the inclusion criteria, and the findings from these studies were grouped according to four emergent themes: rhythmic motoneuron output, afferent feedback integration, membrane excitability, and neuromuscular junction transmission. This synthesis of evidence suggests that CB1 agonists can increase the frequency of cyclical patterns of motoneuron output (i.e., fictive locomotion). Furthermore, a majority of the evidence indicates that activating CB1 receptors at motoneuron synapses promotes excitation of motoneurons by enhancing excitatory synaptic transmission and depressing inhibitory synaptic transmission. The collated study results reveal variable effects of cannabinoids on acetylcholine release at the neuromuscular junction, and the influence of cannabinoids in this area requires more work to ensure precision of findings for CB1 agonist and antagonist impact. Altogether, these reports indicate that the endocannabinoid system is integral within the final common pathway and can impact motor output. This review contributes to understanding the effects of endocannabinoids on synaptic integration at the motoneuron and modulation of motor output.
Topics: Cannabinoids; Motor Neurons; Synapses; Synaptic Transmission; Neuromuscular Junction
PubMed: 37283484
DOI: 10.1152/jn.00460.2022 -
Eye (London, England) Apr 2024Amacrine cells (ACs) are the most structurally and functionally diverse neuron type in the retina. Different ACs have distinct functions, such as neuropeptide secretion... (Review)
Review
Amacrine cells (ACs) are the most structurally and functionally diverse neuron type in the retina. Different ACs have distinct functions, such as neuropeptide secretion and inhibitory connection. Vasoactive intestinal peptide (VIP) -ergic -ACs are retina gamma-aminobutyric acid (GABA) -ergic -ACs that were discovered long ago. They secrete VIP and form connections with bipolar cells (BCs), other ACs, and retinal ganglion cells (RGCs). They have a specific structure, density, distribution, and function. They play an important role in myopia, light stimulated responses, retinal vascular disease and other ocular diseases. Their significance in the study of refractive development and disease is increasing daily. However, a systematic review of the structure and function of retinal VIP-ACs is lacking. We discussed the detailed characteristics of VIP-ACs from every aspect across species and providing systematic knowledge base for future studies. Our review led to the main conclusion that retinal VIP-ACs develop early, and although their morphology and distribution across species are not the same, they have similar functions in a wide range of ocular diseases based on their function of secreting neuropeptides and forming inhibitory connections with other cells.
Topics: Humans; Amacrine Cells; Vasoactive Intestinal Peptide; Retina; Retinal Ganglion Cells; gamma-Aminobutyric Acid
PubMed: 38066110
DOI: 10.1038/s41433-023-02844-x -
Journal of Prosthodontics : Official... Apr 2016Replacement of lost teeth has significant functional and psychosocial effects. The capability of osseointegrated dental implants to transmit a certain amount of... (Review)
Review
PURPOSE
Replacement of lost teeth has significant functional and psychosocial effects. The capability of osseointegrated dental implants to transmit a certain amount of sensibility is still unclear. The phenomenon of developing a certain amount of tactile sensibility through osseointegrated dental implants is called osseoperception. The aim of this article is to evaluate the available literature to find osseoperception associated with dental implants.
MATERIALS AND METHODS
To identify suitable literature, an electronic search was performed using Medline and PubMed database. Articles published in English and articles whose abstract is available in English were included. The articles included in the review were based on osseoperception, tactile sensation, and neurophysiological mechanoreceptors in relation to dental implants. Articles on peri-implantitis and infection-related sensitivity were not included. Review articles without the original data were excluded, although references to potentially pertinent articles were noted for further follow-up. The phenomenon of osseoperception remains a matter of debate, so the search strategy mainly focused on articles on osseoperception and tactile sensibility of dental implants. This review presents the histological, neurophysiological, and psychophysical evidence of osseoperception and also the role of mechanoreceptors in osseoperception.
RESULTS
The literature on osseoperception in dental implants is very scarce. The initial literature search resulted in 90 articles, of which 81 articles that fulfilled the inclusion criteria were included in this systematic review.
CONCLUSION
Patients restored with implant-supported prostheses reported improved tactile and motor function when compared with patients wearing complete dentures.
Topics: Dental Implants; Humans; Mechanoreceptors; Osseointegration; Perception; Peri-Implantitis; Touch
PubMed: 26823228
DOI: 10.1111/jopr.12310 -
PloS One 2022Previous studies proposed possible applications of spectral-domain optical coherence tomography (SD-OCT) measurements in prognosticating pathologies observed in... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Previous studies proposed possible applications of spectral-domain optical coherence tomography (SD-OCT) measurements in prognosticating pathologies observed in overweight/obesity, including ocular, vascular, and neurologic consequences. Therefore, we conducted a systematic review and meta-analysis to investigate the changes in the in SD-OCT measurements of the patients with higher body mass index (BMI) compared to normal weight individuals.
MATERIALS AND METHODS
We conducted a systematic search on PubMed, Scopus, and Embase. The search results underwent two-phase title/abstract and full-text screenings. We then analyzed SD-OCT measurements differences in patients with high BMI and controls, and performed meta-regression, sub-group analysis, quality assessment, and publication bias assessment. The measurements included macular thickness, cup to disc ratio, ganglion cell-inner plexiform layer (GC-IPL) and its sub-sectors, RNFL and peripapillary RNFL (pRNFL) and their sub-layers, and choroidal thickness and its sub-sectors.
RESULTS
19 studies were included in this meta-analysis accounting for 1813 individuals, 989 cases and 824 controls. There was an overall trend towards decreased thickness in high BMI patients, but only two measurements reached statistical significance: temporal retinal nerve fiber layer (RNFL) (Standardized mean difference (SMD): -0.33, 95% confidence interval (CI): -0.53 to -0.14, p<0.01) and the choroidal region 1.0 mm nasal to fovea (SMD: -0.38, 95% CI: -0.60 to -0.16, p<0.01).
CONCLUSION
Some ocular layers are thinner in patients with higher BMI than the controls. These SD-OCT measurements might correlate with adverse events related to increased body weight and have prognostic abilities. As SD-OCT is a robust, rapid and non-invasive tool, future guidelines and studies are needed to evaluate the possibility of their integration into care of the patients with obesity.
Topics: Cross-Sectional Studies; Humans; Nerve Fibers; Obesity; Retinal Ganglion Cells; Tomography, Optical Coherence
PubMed: 35476846
DOI: 10.1371/journal.pone.0267495 -
PloS One 2023Glaucoma is a leading cause of irreversible blindness worldwide. Retinal ganglion cells (RGC), the neurons that connect the eyes to the brain, specifically die in...
PURPOSE
Glaucoma is a leading cause of irreversible blindness worldwide. Retinal ganglion cells (RGC), the neurons that connect the eyes to the brain, specifically die in glaucoma, leading to blindness. Elevated intraocular pressure (IOP) is the only modifiable risk factor, however, many patients progress despite excellent IOP control. Thus, alternative treatment strategies to prevent glaucoma progression are an unmet need. Citicoline has demonstrated neuroprotective properties in central neurodegenerative diseases. However, conclusive evidence of the effect of citicoline on glaucoma progression is missing. This systematic review investigates first-time the therapeutic potential of citicoline in glaucoma patients.
METHODS
The present study was conducted according to the PRISMA 2020 statement. PubMed, Web of Science, Google Scholar, and Embase were accessed in July 2023 to identify all clinical studies investigating the efficacy of citicoline on IOP, the mean deviation of the 24-2 visual field testing (MD 24-2), retinal nerve fibre layer (RNFL), and the pattern electroretinogram (PERG) P50-N95 amplitude in glaucoma patients. The risk of bias was assessed using the Review Manager 5.3 software (The Nordic Cochrane Collaboration, Copenhagen) and the Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I) tool.
RESULTS
Ten studies were eligible for this systematic review, including 424 patients. The mean length of the follow-up was 12.1 ± 11.6 months. The overall risk of bias was low to moderate. The mean age of the patients was 56.7 years. There were no significant differences in the IOP, MD 24-2, RNFL, or PERG P50-N95 amplitude between patients receiving citicoline and the control group. There was no improvement from baseline to the last follow-up in IOP, MD 24-2, RNFL, or PERG P50-N95 amplitude.
CONCLUSION
There is a lack of sufficient evidence to support that citicoline slows the progression of glaucoma.
Topics: Humans; Middle Aged; Cytidine Diphosphate Choline; Glaucoma, Open-Angle; Intraocular Pressure; Glaucoma; Retinal Ganglion Cells; Blindness
PubMed: 37768938
DOI: 10.1371/journal.pone.0291836 -
Brazilian Journal of Otorhinolaryngology 2023To analyze, by means of a systematic review and meta-analysis, the proportion of patients with Meniere's disease who have altered caloric test and vHIT, as well as to... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To analyze, by means of a systematic review and meta-analysis, the proportion of patients with Meniere's disease who have altered caloric test and vHIT, as well as to determine the prevalence of altered caloric test and normal vHIT dissociation in the diagnosis of Meniere's disease.
METHODS
The literature search had no restriction regarding the period of publication on the following indexed data platforms: PubMed, PubMed PMC, BVS-Bireme, Web of Science, Embase and Cochrane Library. Articles that evaluated patients with Meniere's disease who underwent caloric test and vHIT were included. Two researchers independently conducted the analysis of the articles, promoting the selection and capture of data, following the recommendations of the PRISMA method, and complying with the criteria for articles inclusion and exclusion defined in the research protocol. In case of disagreement during the selection process, a third researcher was included for analysis.
RESULTS
From a total of 427 initial studies, the researchers selected 12 articles, published between 2014 and 2021, with a total of 708 patients evaluated, with a mean age of 52.72 years old. The prevalence of patients with Meniere's disease with altered caloric reflex test was 64% (95% CI 57%‒71%), while the prevalence of altered vHIT was only 28% (95% CI 16%-40%). The prevalence of the altered caloric test + normal vHIT dissociation was 47% (95% CI 37%-57%).
CONCLUSION
The video head impulse test and the caloric test are valuable tools for vestibular assessment. The dissociation of findings between these two tests in patients with Meniere's disease was more prevalent in this meta-analysis and may be a result of the tonotopy of specialized hair cells in the ampullary crest. The prevalence of altered caloric test was 64% and anormal vHIT was 28%. The dissociation caloric asymmetry and normal vHIT was observed in 47% of the patients.
Topics: Humans; Middle Aged; Meniere Disease; Head Impulse Test; Caloric Tests; Reflex, Vestibulo-Ocular; Hair Cells, Auditory
PubMed: 37354884
DOI: 10.1016/j.bjorl.2023.101279 -
Biomedicine & Pharmacotherapy =... Nov 2023Humans rely on vision as their most important sense. This is accomplished by photoreceptors (PRs) in the retina that detect light but cannot function without the support... (Review)
Review
Humans rely on vision as their most important sense. This is accomplished by photoreceptors (PRs) in the retina that detect light but cannot function without the support and maintenance of the retinal pigment epithelium (RPE). In subretinal hemorrhage (SRH), blood accumulates between the neurosensory retina and the RPE or between the RPE and the choroid. Blood breakdown products subsequently damage PRs and the RPE and lead to poor vision and blindness. Hence, there is a high need for options to preserve the retina and visual functions. We conducted a systematic review of the literature in accordance with the PRISMA guidelines to identify the cell death mechanisms in RPE and PRs after SRH to deepen our understanding of the pathways involved. After screening 736 publications published until November 8, 2022, we identified 19 records that assessed cell death in PRs and/or RPE in experimental models of SRH. Among the different cell death mechanisms, apoptosis was the most widely investigated mechanism (11 records), followed by ferroptosis (4), whereas necroptosis, pyroptosis, and lysosome-dependent cell death were only assessed in one study each. We discuss different therapeutic options that were assessed in these studies, including the removal of the hematoma/iron chelation, cytoprotection, anti-inflammatory agents, and antioxidants. Further systematic investigations will be necessary to determine the exact cell death mechanisms after SRH with respect to different blood breakdown components, cell types, and time courses. This will form the basis for the development of novel treatment options for SRH.
Topics: Humans; Retinal Pigment Epithelium; Retina; Cell Death; Photoreceptor Cells; Hemorrhage
PubMed: 37742603
DOI: 10.1016/j.biopha.2023.115572 -
Pflugers Archiv : European Journal of... Apr 2022Sensory neurons are responsible for the generation and transmission of nociceptive signals from the periphery to the central nervous system. They encompass a broadly... (Review)
Review
Sensory neurons are responsible for the generation and transmission of nociceptive signals from the periphery to the central nervous system. They encompass a broadly heterogeneous population of highly specialized neurons. The understanding of the molecular choreography of individual subpopulations is essential to understand physiological and pathological pain states. Recently, it became evident that species differences limit transferability of research findings between human and rodents in pain research. Thus, it is necessary to systematically compare and categorize the electrophysiological data gained from human and rodent dorsal root ganglia neurons (DRGs). In this systematic review, we condense the available electrophysiological data defining subidentities in human and rat DRGs. A systematic search on PUBMED yielded 30 studies on rat and 3 studies on human sensory neurons. Defined outcome parameters included current clamp, voltage clamp, cell morphology, pharmacological readouts, and immune reactivity parameters. We compare evidence gathered for outcome markers to define subgroups, offer electrophysiological parameters for the definition of neuronal subtypes, and give a framework for the transferability of electrophysiological findings between species. A semiquantitative analysis revealed that for rat DRGs, there is an overarching consensus between studies that C-fiber linked sensory neurons display a lower action potential threshold, higher input resistance, a larger action potential overshoot, and a longer afterhyperpolarization duration compared to other sensory neurons. They are also more likely to display an infliction point in the falling phase of the action potential. This systematic review points out the need of more electrophysiological studies on human sensory neurons.
Topics: Action Potentials; Animals; Electrophysiological Phenomena; Ganglia, Spinal; Humans; Pain; Rats; Sensory Receptor Cells
PubMed: 35031856
DOI: 10.1007/s00424-021-02656-6 -
Survey of Ophthalmology 2023Optical coherence tomography is a noninvasive imaging technology using the optical reflectivity of tissues that is capable of detecting quantitative and qualitative... (Meta-Analysis)
Meta-Analysis Review
Optical coherence tomography is a noninvasive imaging technology using the optical reflectivity of tissues that is capable of detecting quantitative and qualitative biomarkers of age-related macular degeneration (AMD) that cannot be similarly recognized in conventional imaging. We systematically searched PubMed and Embase databases to identify relevant articles to this subject. A fixed-effect or random-effect model was applied for the meta-analysis based on the heterogeneity level. In addition, subgroup analyses, meta-regression, publication bias, and quality assessment were also performed. Twenty-five studies with 1,632 cases and 1,445 healthy controls in total were included. Our results revealed that, when compared to controls, AMD subjects showed a significantly lower thickness in the choroid at 500 µm temporal, 1,500 µm nasal, and temporal to the fovea, subfoveal choroid, average peripapillary retinal nerve fiber layer, and average macular ganglion cell complex (GCC); however, average and central choroidal thickness 500 µm nasal, 1,000 µm nasal and temporal to the fovea, central and parafoveal macular GCC, retinal nerve fiber layer, and inner plexiform layer, and central macular thickness did not change significantly. Various regional analyses showed several other significant differences. The findings of the current study confirm that some retinal layers are altered in AMD patients compared to healthy controls. Thus, future studies are required to derive more definitive conclusions.
Topics: Humans; Tomography, Optical Coherence; Nerve Fibers; Retinal Ganglion Cells; Choroid; Macular Degeneration
PubMed: 35908660
DOI: 10.1016/j.survophthal.2022.07.006 -
International Ophthalmology Sep 2021Retinal nerve fiber/ganglion cell layer (RNFL/GCL) thickness measured using optical coherence tomography has been proposed as an ocular biomarker for children with... (Meta-Analysis)
Meta-Analysis Review
The association between attention-deficit/hyperactivity disorder and retinal nerve fiber/ganglion cell layer thickness measured by optical coherence tomography: a systematic review and meta-analysis.
PURPOSE
Retinal nerve fiber/ganglion cell layer (RNFL/GCL) thickness measured using optical coherence tomography has been proposed as an ocular biomarker for children with attention-deficit/hyperactivity disorder (ADHD), but findings varied in different studies. This study aims to determine the association between RNFL/GCL thickness and ADHD in children by systematic review and meta-analysis.
METHODS
We performed a literature search in Embase, PubMed, Medline, Web of Science, and PsycINFO for relevant articles published up to February 29, 2020. All studies with original data comparing RNFL/GCL thickness in ADHD and healthy children were included. The Newcastle Ottawa Scale was used to assess bias risk and quality of evidence. Pooled estimates of the differences in thickness of RNFL or GCL between ADHD and healthy subjects were generated using meta-analysis with a random-effect model due to significant inter-study heterogeneity. Sensitivity analysis was also performed.
RESULTS
We identified four eligible studies involving a total of 164 ADHD and 150 control subjects. Meta-analysis revealed that ADHD in children was associated with a reduction in global RNFL thickness (SMD, - 0.23; 95% CI - 0.46, - 0.01; p = 0.04). The global GCL thickness was examined in two studies with 89 ADHD and 75 control subjects, but the pooled difference in global GCL thickness between ADHD children and controls was not statistically significant (SMD, - 0.34; 95% CI - 1.25, 0.58; p = 0.47).
CONCLUSION
Existing evidence suggests a possible association between ADHD and RNFL thinning in children. In view of the limited number of reports, further studies in large cohorts should be warranted.
Topics: Attention Deficit Disorder with Hyperactivity; Humans; Nerve Fibers; Retina; Retinal Ganglion Cells; Tomography, Optical Coherence
PubMed: 34014463
DOI: 10.1007/s10792-021-01852-8