Sympathetic nerve fibers in human cervical and thoracic vagus nerves.
BACKGROUND
Vagus nerve stimulation (VNS) therapy has been used for chronic heart failure and is believed to improve imbalance of autonomic control by increasing parasympathetic activity. Although it is known that there is neural communication between the VN and the cervical sympathetic trunk, there are few data regarding the quantity and/or distribution of the sympathetic components within the vagus nerve (VN).


OBJECTIVE
To examine the sympathetic components within the human VN and correlate them with the presence of cardiac and neurologic diseases.


METHODS
We performed immunohistochemistry on 31 human cervical and thoracic VNs (total 104 VNs) from autopsies and reviewed the patients' records. We correlated the quantity of sympathetic nerve fibers within the VNs with cardiovascular and neurologic disease states.


RESULTS
All 104 VNs contain tyrosine hydroxylase (TH)-positive (sympathetic) nerve fibers; the mean TH-positive areas were 5.47% in the right cervical VN, 3.97% in the left cervical VN, 5.11% in the right thoracic VN, and 4.20% in the left thoracic VN. The distribution of TH-positive nerve fibers varied from case to case: central, peripheral, or scattered throughout nerve bundles. No statistically significant differences in nerve morphology were seen between diseases in which VNS is considered effective (depression and chronic heart failure) and other cardiovascular diseases or neurodegenerative disease.


CONCLUSIONS
Human VNs contain sympathetic nerve fibers. The sympathetic component within the VN could play a role in physiologic effects reported with VNS. The recognition of sympathetic nerve fibers in the VNs may lead to better understanding of the therapeutic mechanisms of VNS.
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California. Electronic address: ASeki@mednet.ucla.edu.
Atsuko
A
Seki
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California.
Hunter R
HR
Green
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California.
Thomas D
TD
Lee
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California.
LongSheng
L
Hong
Krannert Institute of Cardiology, Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.
Jian
J
Tan
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California.
Harry V
HV
Vinters
Krannert Institute of Cardiology, Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.
Peng-Sheng
PS
Chen
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California.
Michael C
MC
Fishbein
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005260:Female; D006333:Heart Failure / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000378:metabolism / Q000473:pathology*; D017783:Superior Cervical Ganglion / Q000378:metabolism / Q000473:pathology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D014630:Vagus Nerve / Q000378:metabolism / Q000473:pathology*
D014446:Tyrosine 3-Monooxygenase; D002795:Choline O-Acetyltransferase
Cervical vagus nerves; Ganglion cells; Heart failure; Sympathetic nerves; Vagal nerve stimulation