Autonomic innervation of tendons, ligaments and joint capsules. A morphologic and quantitative study in the rat.
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.
Ackermann
P W
PW
Department of Surgical Sciences, Karolinska Institutet, Karolinska Hospital, Stockholm, Sweden. paul.ackermann@ks.se
Li
J
J
Finn
A
A
Ahmed
M
M
Kreicbergs
A
A
D000125:Achilles Tendon / Q000737:chemistry / Q000294:innervation*; D000818:Animals; D001341:Autonomic Nervous System / Q000033:anatomy & histology* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D017885:Collateral Ligaments / Q000737:chemistry / Q000294:innervation*; D005455:Fluorescent Antibody Technique; D019084:Fluorescent Antibody Technique, Indirect; D017746:Joint Capsule / Q000737:chemistry / Q000294:innervation*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000737:chemistry / Q000294:innervation*; D009412:Nerve Fibers / Q000737:chemistry; D009478:Neuropeptide Y / Q000032:analysis; D009638:Norepinephrine / Q000032:analysis; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D014660:Vasoactive Intestinal Peptide / Q000032:analysis
D009478:Neuropeptide Y; D014660:Vasoactive Intestinal Peptide; D009638:Norepinephrine