Autonomic innervation of tendons, ligaments and joint capsules. A morphologic and quantitative study in the rat

Abstract

We analyzed the neuronal occurrence of autonomic transmitters; noradrenaline (NA), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP), in the Achilles tendon, medial and lateral collateral ligaments and knee joint capsule in the rat — by immunohistochemistry (IHC). In addition, the tissue concentrations of the sympathetic neuropeptide, NPY, and the parasympathetic peptide, VIP, were determined by radioimmunoassay (RIA). IHC demonstrated nerve fibers containing sympathetic vasoconstrictors — NA and NPY‐ and the parasympathetic vasodilator, VIP, in all tissues. NPY‐ and NA‐positive nerve fibers were predominantly observed in larger blood vessels, whereas, nerve fibers immunoreactive to VIP were found in smaller vessels. In many nerve fibers a co‐localization of the transmitters was seen. RIA showed that the concentration of NPY compared to VIP was 15‐times higher in ligaments and twice as high in tendons and capsules. The differences noted may reflect a difference in vulnerability to degenerative conditions. In pathological conditions, dysregulation of autonomic transmitters in hypovascularized tissues subjected to repetitive mechanical load may contribute to tissue hypoxia leading to degeneration and rupture of tendons and ligaments. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

Gene intervention in ligament and tendon: current status, challenges, future directions

“…9,11 Specialized nerve receptors exist that participate in joint proprioception and recent work has shown the importance of innervation in the healing of ligaments. [12][13][14] The major research efforts have focused on the description of ligament and tendon matrix as well as their biomechanical properties. 1,4,15 The matrix is predominantly composed of water (65-80%).…”

Early nerve regeneration after Achilles tendon rupture — a prerequisite for healing? A study in the rat

“…A variety of neuronal mediators, so-called neuropeptides, has been identified and found to exert trophic effects in several tissues in addition to nociception, vasoaction and proinflammation [19,32,34]. As for tendons, we were recently able to demonstrate the presence of sensory and autonomic neuropeptides in normal Achilles tendon of the rat [1,2]. These neuropeptides have also been found in tissues from patients with lateral elbow tendinosis [24,25].…”

Healing of subcutaneous tendons: Influence of the mechanical environment at the suture line on the healing process

“…The majority of nerve fibers are located within the paratenon and not the tendon itself [29] . Paratenon nerves form rich plexuses that send a few branches penetrating the epitenon.…”

“…It has been suggested that the nerve fibers regulate blood flow within the tendon. Furthermore, free nerve fibers containing substance P and calcitonin gene-related peptide (CGRP) might be involved in collecting sensory information (including pain) and relaying this to the central nervous system [29] . Zaffagnini et al [31] have reported the presence of Ruffini and Pacinian corpuscles within the pes anserinus tendons, particularly at their tibial attachment sites.…”