Biology subjects

Pitman, M. J.

Publications and source records attributed to Pitman, M. J..

3 recordsLinked to original sources

bioRxiv2023

Transcriptome analysis of left-right intrinsic laryngeal muscles shows divergent expression of genes associated with innervation

Objectives/HypothesisRecurrent laryngeal nerve injury diagnosed as idiopathic or due to short-term surgery-related intubation exhibits a higher incidence of left-sided paralysis. While this is often attributed to nerve length, it is hypothesized there are asymmetric differences in the expression of genes related to neuromuscular function that may impact reinnervation and contribute to this laterality phenomenon. To test this hypothesis, this study analyzes the transcriptome profiles of the intrinsic laryngeal muscles (ILMs), comparing gene expression in the left versus right, with particular attention to genetic pathways associated with neuromuscular function. Study DesignLaboratory experiment. MethodsRNA was extracted from the left and right sides of the rat posterior cricoarytenoid (PCA), lateral thyroarytenoid (LTA), and medial thyroarytenoid (MTA), respectively. After high-throughput RNA-Sequencing (RNA-Seq), 88 samples were organized into 12 datasets according to their age (P15/adult), sex (male/female), and muscle type (PCA/LTA/MTA). A comprehensive bioinformatics analysis was conducted to compare the left-right ILMs across different conditions. Results774 differentially expressed genes (DEGs) were identified across the 12 experimental groups, revealing age, sex, and muscle-specific differences between the left versus right ILMs. Enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways implicated several genes with a left-right laryngeal muscle asymmetry. These genes are associated with neuronal and muscular physiology, immune/inflammatory response, and hormone control. ConclusionBioinformatics analysis confirmed divergent transcriptome profiles between the left-right ILMs. This preliminary study identifies putative gene targets that will characterize ILM laterality. Level of EvidenceN/A LAY SUMMARYVocal fold paralysis is more common on the left. This study shows left versus right differences in gene expression related to innervation, suggesting the increased rate of left recurrent laryngeal nerve paralysis may be associated with genetic differences, not just nerve length.

neuroscience↗

bioRxiv2023

The Expression of Vesicular Glutamate Transporter 1 (VGLUT1) in the Rat Larynx and Implications for Laryngeal Proprioception

Proprioception plays a crucial role in laryngeal function. Further, dysfunctional proprioception likely contributes to disorders such as laryngeal dystonia, dysphagia and vocal fold paresis. Despite this, the physiology of laryngeal proprioception is not well-understood. Controversy remains over whether canonical proprioceptive organs, like muscle spindles (MS) even exist in the intrinsic laryngeal muscles (ILM). Vesicular Glutamate Transporter 1 (VGLUT1) expression has been described in the sensory afferents of MS. This studys primary aim is to determine whether the ILM contain MS using VGLUT1. This is a novel approach, as prior studies have relied on morphology and myosin composition to study this question. Secondarily, we describe the pattern of VGLUT1 expression in the rat larynx, Larynges of 62 Sprague-Dawley rats distributed across 5 age groups (P3, P8, P11, P14-15, and adult), were sectioned and immunostained for VGLUT1 and beta-tubulin III. Other markers (S46, GNAT3, PLC{beta}2, S100b, CGRP) were used to further characterize identified afferent innervation. Of 62 rats, MS were identified in the lateral thyroarytenoid muscles of just three P8 rats, and no golgi tendon organs (GTO) were seen. VGLUT1-positive intramuscular receptor-like entities were observed ILM, and VGLUT1-positive nerve endings were observed in the laryngeal mucosa, concentrated around the arytenoid cartilage. Employing VGLUT1 immunostaining, this study shows that rat intrinsic laryngeal muscles rarely express MS and do not express GTO. This leaves open the possibility that the larynx exhibits a unique proprioceptive apparatus. VGLUT1-positive intramuscular and mucosal structures provide candidates for an alternative system. Further defining the role of these sensory organs will increase our understanding of vocal fold function and ultimately lead to better treatment of vocal fold disorders. KEY POINTSO_LIDysfunctional laryngeal proprioception likely contributes to disorders such as laryngeal dystonia, dysphagia, and vocal fold paresis. Unlike proprioception of skeletal muscles, proprioception of the intrinsic laryngeal muscles is poorly understood. C_LIO_LIIn the present study we demonstrate that canonical proprioceptive organs (muscles spindles and Golgi tendon organs) are rarely expressed in the rat larynx, by studying the expression pattern of VGLUT1. C_LIO_LIWe also demonstrate the presence of other sensory innervation and structures which may contribute to an alternative proprioceptive circuitry, which requires further study. C_LI

neuroscience↗

bioRxiv2022

Expression of GDNF Receptors Within Nucleus Ambiguus During Rat Development

ObjectiveUpregulation of GDNF and its receptors is observed during laryngeal reinnervation after nerve injury. In contrast, little is known regarding the expression of GDNF receptors in the formation of the nucleus ambiguus (NA) and its innervation of the larynx during embryogenesis. Differences may suggest therapeutic targets after nerve injury. Study DesignLaboratory experiment. MethodsRat brainstems at E14, E16, E18, E20, adult (4 animals/timepoint) were sectioned and stained for GDNF receptors: GFR-1, GFR-2, GFR-3, and Ret. Islet1 and ChAT were used as markers for motoneuron cell bodies. Sections were observed using Zeiss Axio Imager M2 Microscope and quantified using Image J. ResultsExpression of all four GDNF receptors was identified within the nucleus ambiguus, as well as hypoglossal and facial nuclei of the adult rat brainstem. During rat development, GFR-3 and Ret exhibited upregulation within the nucleus ambiguus at E14 whereas GFR-1 began showing upregulation at E20. GFR-2 exhibited no upregulation at embryonic timepoints. Conclusion: Upregulation of the GDNF receptors within the nucleus ambiguus occur after laryngeal muscles innervation during development and may associated with maturation and maintenance of the neuromuscular synapses of the larynx before and after birth. No differences among ambiguus, hypoglossal, and facial nuclei was observed.

neuroscience↗