Vasomotion of intraradicular microvessels in rat.
METHODS
This study is to investigate the changes of vasomotion of intraradicular microvessels in vivo.


OBJECTIVE
We have observed microvascular corrosion casts of the lumbar nerve root by scanning electron microscopy and used an immunohistochemical technique to investigate the presence and distribution of autonomic and sensory nerve in blood vessels of the nerve root.


BACKGROUND
It is generally considered that the genesis of radiculopathy associated with the degenerative conditions of the spine may result from both mechanical compression and circulatory disturbance. However, the neurogenic control of intraradicular blood flow has received little attention in the past.


METHODS
For three-dimensional observation of intraradicular vessels, we used scanning electron microscopic examination of microvascular corrosion casts in ten Wister rats. To investigate the mechanism of vasomotion of the nerve root, we used immunohistochemical methods. The sections were incubated overnight with antisera to tyrosine hydroxylase, choline acetyl transferase, substance P, calcitonin-gene-related peptide, vasoactive intestinal peptide, somatostatin, neuropeptide Y, leucine-enkephalin, cholecystokinin octapeptide, brain-nitric oxide synthase, and endothelium-nitric oxide synthase. Abidin-biotin complex method was used as the immunohistochemical procedure and the sections were observed under the light microscope.


RESULTS
The general view of whole vascular casts of the lumbar spinal cord and nerve roots showed a high density of vessels. Bifurcation or anastomoses of capillaries approximately took place at right angles in a T-shaped pattern and capillaries showed a lot of ring-like compressions. This ring-like compression on the cast may represent a vascular sphincter in the microvessels. This study also reveals the existence of perivascular adrenergic, cholinergic, peptidergic, and nitroxydergic innervation with a possible role in neurogenic regulation of nerve root circulation.


CONCLUSIONS
Perivascular nerve plexuses around intraradicular microvessels suggest that the autonomic nerves play an important role in intraradicular circulation.
Kobayashi
Shigeru
S
Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, The University of Fukui, Matsuoka, Fukui, Japan. kshigeru@u-fukui.ac.jp
Mwaka
Erisa Sabakaki
ES
Meir
Adam
A
Uchida
Kenzo
K
Takeno
Kenichi
K
Miyazaki
Tsuyoshi
T
Kubota
Masafumi
M
Nakajima
Hideaki
H
Nomura
Eiki
E
Yoshizawa
Hidezo
H
Baba
Hisatoshi
H
D000818:Animals; D017776:Autonomic Pathways / Q000378:metabolism / Q000648:ultrastructure*; D001808:Blood Vessels / Q000294:innervation* / Q000378:metabolism / Q000648:ultrastructure*; D002196:Capillaries / Q000502:physiology / Q000648:ultrastructure; D016319:Corrosion Casting / Q000379:methods; D007150:Immunohistochemistry; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D009131:Muscle, Smooth, Vascular / Q000294:innervation / Q000378:metabolism / Q000648:ultrastructure; D009479:Neuropeptides / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D011843:Radiculopathy / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000502:physiology; D011984:Sensory Receptor Cells / Q000378:metabolism / Q000648:ultrastructure; D013126:Spinal Nerve Roots / Q000098:blood supply* / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology; D014666:Vasomotor System / Q000378:metabolism / Q000648:ultrastructure*
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009569:Nitric Oxide