title: Interdependency between mechanical parameters and afferent nerve discharge in hypertrophic intestine of rats.
abstract: Partial intestinal obstruction causes smooth muscle hypertrophy, enteric neuronal plasticity, motility disorders, and biomechanical remodeling. In this study we characterized the stimulus-response function of afferent fibers innervating the partially obstructed jejunum. A key question is whether changes in afferent firing arise from remodeled mechanical tissue properties or from adaptive afferent processes. Partial obstruction was created by placing a polyethylene ring for 2 wk in jejunum of seven rats. Sham obstruction was made in six rats and seven rats served as normal controls. Firing from mesenteric afferent nerve bundles was recorded during mechanical ramp, relaxation, and creep tests. Stress-strain, spike rate increase ratio (SRIR), and firing rate in single units were assessed for evaluation of interdependency of the mechanical stimulations, histomorphometry data, and afferent nerve discharge. Partial intestinal obstruction resulted in hypertrophy and jejunal stiffening proximal to the obstruction site. Low SRIR at low strains during fast distension and at high stresses during slow distension was found in the obstructed rats. Single unit analysis showed increased proportion of mechanosensitive units but absent high-threshold (HT) units during slow stimulation, decreased number of HT units during fast stimulation, and shift from HT sensitivity towards low threshold sensitivity in the obstructed jejunum. Biomechanical remodeling and altered afferent response to mechanical stimulations were found in the obstructed jejunum. Afferents from obstructed jejunum preserved their function in encoding ongoing mechanical stimulation but showed changes in their responsiveness. The findings support that mechanical factors rather than adaption are important for afferent remodeling.
authors.affiliation: GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education; Bioengineering College of Chongqing University, Chongqing, China;
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Clinical Medicine, Aarhus University, Aarhus, Denmark;
authors.forename: Jingbo
authors.initials: J
authors.lastname: Zhao
authors.affiliation: China-Japan Friendship Hospital, Beijing, China;
authors.forename: Pengmin
authors.initials: P
authors.lastname: Chen
authors.affiliation: Graduate School of Advanced Integrated Science, Chiba University, Chiba, Japan; and.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Nakaguchi
authors.affiliation: Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Grundy
authors.affiliation: GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education; Bioengineering College of Chongqing University, Chongqing, China; hag@giome.org.
authors.forename: Hans
authors.identifier: http://orcid.org/0000-0002-5792-2845
authors.initials: H
authors.lastname: Gregersen
mesh_terms: D000344:Afferent Pathways / Q000503:physiopathology*; D000818:Animals; D001696:Biomechanical Phenomena; D001835:Body Weight; D005071:Evoked Potentials; D006984:Hypertrophy; D007415:Intestinal Obstruction / Q000503:physiopathology*; D007422:Intestines / Q000294:innervation; D007583:Jejunum; D008297:Male; D008643:Mesentery / Q000294:innervation; D009126:Muscle Relaxation; D009475:Neurons, Afferent; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar
keywords: afferent; jejunum; partial obstruction; strain; stress