Abnormal afferent nerve endings in the soft palatal mucosa of sleep apnoics and habitual snorers

Regul Pept. 1997 Jul 23;71(1):29-36. doi: 10.1016/s0167-0115(97)01016-1.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Biopsy
  • Calcitonin Gene-Related Peptide / metabolism
  • Humans
  • Immunohistochemistry
  • Male
  • Middle Aged
  • Mouth Mucosa / innervation*
  • Nasal Mucosa / innervation*
  • Nerve Tissue Proteins / metabolism
  • Neurons, Afferent / metabolism
  • Neurons, Afferent / pathology*
  • Palate / innervation*
  • Palate / physiopathology
  • Sleep Apnea Syndromes / metabolism
  • Sleep Apnea Syndromes / pathology*
  • Snoring / metabolism
  • Snoring / pathology*
  • Substance P / metabolism
  • Thiolester Hydrolases / metabolism
  • Ubiquitin Thiolesterase


  • Nerve Tissue Proteins
  • Substance P
  • Thiolester Hydrolases
  • Ubiquitin Thiolesterase
  • Calcitonin Gene-Related Peptide