title: Abnormal afferent nerve endings in the soft palatal mucosa of sleep apnoics and habitual snorers.
abstract: Habitual snoring precedes obstructive sleep apnea (OSA), but the pathophysiological mechanisms behind progression are still unclear. The patency of upper airways depends on a reflexogen mechanism reacting on negative intrapharyngeal pressure at inspiration, probably mediated by mucosal receptors, i.e., via afferent nerve endings. Such nerves contain a specific nerve protein, protein-gene product 9.5 (PGP 9.5) and in some cases substance P (SP) and calcitonin gene-related (CGRP). Biopsies of the soft palatial mucosa were obtained from non-smoking men ten OSA patients, 11 habitual snorers and 11 non-snoring controls. The specimens were immunohistochemically analyzed for PGP 9.5, SP and CGRP. As compared to controls, an increased number of PGP-, SP- and CGRP-immunoreactive nerves were demonstrated in the mucosa in 9/10 OSA patients and 4/11 snorers, in addition to varicose nerve endings in the papillae and epithelium. Using double staining methodology, it could be shown that SP- and CGRP-like immunoreactivities (LIs) often coexisted in these fibres, as did CGRP- and PGP 9.5-LIs. The increased density in sensory nerve terminals are interpreted to indicate an afferent nerve lesion. Our results support the hypothesis of a progressive neurogenic lesion as a contributory factor to the collapse of upper airways during sleep in OSA patients.
authors.affiliation: Department of Otorhinolaryngology, Söder Hospital, Karolinska Institute, Stockholm, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Friberg
authors.forename: B
authors.initials: B
authors.lastname: Gazelius
authors.forename: T
authors.initials: T
authors.lastname: Hökfelt
authors.forename: B
authors.initials: B
authors.lastname: Nordlander
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000294:innervation*; D009297:Nasal Mucosa / Q000294:innervation*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009475:Neurons, Afferent / Q000378:metabolism / Q000473:pathology*; D010159:Palate / Q000294:innervation* / Q000503:physiopathology; D012891:Sleep Apnea Syndromes / Q000378:metabolism / Q000473:pathology*; D012913:Snoring / Q000378:metabolism / Q000473:pathology*; D013373:Substance P / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000378:metabolism; D043222:Ubiquitin Thiolesterase
chemical_list: D009419:Nerve Tissue Proteins; D013373:Substance P; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase; D015740:Calcitonin Gene-Related Peptide