Surgical Science, 2011, 2, 188-192
doi:10.4236/ss.2011.24041 Published Online June 2011 (http://www.SciRP.org/journal/ss)
Role of the Peripheral Sympathetic Innervations in
Controlling Cerebral Blood Flow after the Transection of
Bilateral Superior Cervical Sympathetic Ganglia Two
Weeks Later
Cheng-Ta Hsieh1,2, Shinn-Zong Lin3, Ming-Ying Liu1
1Department of Neurological Surgery, Tri-Service General Hospital, Nation al Def ense
Medical Center, Taipei, China
2Division of Ne urosurgery, Departme nt of S u r gery, Sijhih Cathay General Hospital,
New Taipei, China
3Division of Ne urosurgery, Departme nt of S u r gery, China Medical University Hospital,
Taichung, Taiwan , China
Received March 30, 2011; revised May 5, 2011; accepted May 10, 2011.
Abstract
Background: Cerebral blood vessels are mainly supplied by sympathetic nerves arising from the superior
cervical ganglia and cerebral blood volume may be influenced by bilateral superior cervical ganglionectomy
(SCG). Various stages of cerebral blood volume changes depended on the time following bilateral excision
of SCG. In this study, we emphasize the subacute effect (two weeks) on the local cerebral blood flow
(LCBF). Material and Methods: Sprague-Dawley rats weighing 250 - 400 gm (n = 20) were selected into two
groups. Under the ambient temperature 20˚C, the first group animals (n = 10) received sham operation and
the other group animals (n = 10) underwent bilateral SCG. The LCBF and O2 delivery of 14 brain structures
were measured for each animal by the use of 14C-iodoantipyrine technique two weeks after the operation.
Results: The average of LCBF was decreased from 150 ml/100 gm/min to 129 ml/100 gm/min after bilateral
SCG. Only the LCBF at basal ganglia was increased from 108 ml/min/100 g in the sham-operated group to
118 ml/min/100g in the SCG group. A mean of 14% reduction of LCBF was estimated. In 14 brain structures,
the delivery amount of O2 was all decreased, except in basal ganglia. However, these changes of LCBF and
the delivery amount of O2 at these 14 brain structures did not reach the significant differences. Conclusions:
The present results show that chronic effect (two weeks) of bilateral SCG on LCBF was not only in a de-
crease of the LCBF, but also a decrease of local cerebral O2 delivery. However, the changes didn’t show the
significant differences.
Keywords: Local Cerebral Blood Flow, Cervical Ganglia, Ganglionectomy
1. Introduction
The relationship between autonomic regulation and
cerebral blood flow (CBF) has long been a subject of
considerable interest in studying the mechanisms of
neurovascular disorders such as hypertensive encepha-
lopathy, migraine and syncope [1]. Cerebral blood ves-
sels are mainly supplied by sympathetic nerves arising
from the superior cervical ganglia, and the sympathetic
nerves, heterogeneously distributed throughout the cere-
brocortex [2,3]. Although nervous stimulation or adren-
ergic agonists lead to vasoconstriction, superior cervical
ganglionectomy (SCG) or adrenergic antagonists do not
usually affect regional CBF [4,5]. “Microregional” dif-
ferences in the cerebrocortex without decreasing global
and regional blood flow, resulted from limit flow and/or
decrease red cell velocity, has been hypothesized [6].
The subacute effect of SCG on cerebral microcirculation
remains obscure. In this study, we evaluate local cerebral
blood flow (LCBF) and the delivery amount of O2 at 14

C.- T. HSIEH ET AL.
189
brain structures in experimental rats underwent bilateral
SCG.
2. Material and Methods
Male Sprague-Dawley rats weighing 250 to 400 gm were
used for these experiments. These animals were fasted
for approximately 12 hours before surgery.
2.1. Surgical Techniques
The rats were anesthetized with 3% halothane for 2 - 4
minutes until they were calm down. The anesthesia was
continued with 1.5% halothane in nitrous oxide (70%)
and oxygen (30%) for the period of surgery. The femoral
artery and femoral vein were catheterized on both sides
of the animals with polyethylene tube (PE-50). The sur-
gical wounds were covered with xylocaine jelly. A plas-
ter cast was fitted from midthorax to midthigh to immo-
bilize the hind limbs and protect the catheters. Then the
anesthesia was stopped and the animals were allowed to
recover the consciousness.
2.2. Experimental Design
The rats were exposed in normal condition (ambient
temperature 20˚C) and their physiological condition was
assessed by measurement of hematocrit (Hct), hemoglo-
bin (HgB), pH, pCO2, pO2, volume and saturation of O2,
systolic blood pressure (SBP), diastolic blood pressure
(DBP), mean arterial blood pressure (MBP), pulse rate
(PR), weight, and plasma glucose level. Total 20 male
Sprague-Dawley rats were divided into two groups:
Group A (n = 10) as the control group underwent sham
operation. Group B (n = 10) received bilateral superior
cervical ganglionectomy. Local cerebral blood flow and
O2 delivery were measured post each operation. Superior
cervical ganglionectomy was performed as: the salivary
glands were exposed through sublingular incision in the
neck and each superior cervical ganglion was identified
at the bifurcation of the common carotid artery beside the
trachea. The ganglia were totally removed en bloc from
both sides. Sham operation received the same procedure
as above except the removal of SCG. After recovering
from the anesthesia, the rats were put in a cage with food
as usual. Two weeks later, the rats were re-anesthetized
for measurement of LCBF.
2.3. Measurement of Local Cerebral Blood Flow
The LCBF was measured by the 14C-iodoantipyrine (IAP)
technique developed by Sakurada et al. [7], as modified
by Otsuka et al. [8]. Before beginning IAP infusion, a
single extracorporeal arteriovenous (AV) shunt was
formed by shortening and connecting the femoral artery
and vein catheters on one side with a 3-cm length of
silicone rubber tubing. At the beginning of the experi-
mental period (t = 0), an intravenous infusion of ap-
proximately 50uCi of 14C –IAP in 1ml saline was started
using a variable speed infusion pump. The rate of infu-
sion was increased during the experiment according to a
schedule that yielded a linearly rising concentration of
IAP in the blood. Series arterial blood sampling was
performed (every 5 sec starting at t = 0) by puncturing
the extracorporeal AV loop with a 22-gauge needle on a
plungerless syringe and collecting 60 ~ 80 µl blood over
the next 2 - 4 sec. The rats were decapitated at t = 30 sec,
and their brains were quickly removed., frozen in
2-methylbutane cooled to –45˚C, and stored in a plastic
bag at –80˚C until the time of sectioning.
Plasma 14C-radioactivity was assayed by beta counting.
The frozen brain was cut into a series of 20 µm thick
sections in a cryostat at –20˚C starting at the area
postrema, which lies at the caudal end of the fourth ven-
tricle. Selected brain sections from inferior collicullus,
superior collicullus, midbrain, occipital cortex, pons,
medulla oblongata, hippocampus, hypothalamus, thala-
mus, corpus callosum, temporal cortex, frontal cortex,
basal ganglia, sensorimotor cortex, cerebellar vermis
were dried and placed in X-ray cassettes along with sets
of previously calibrated 14C standards. Many of the areas
were selected because they had been included in the re-
ports of Kadekaro et al. [9] and our previous study [10].
Un-exposed X-ray film (Kodak SB-5) was placed over
the brain section and standards. After approximately 12
days of exposure, the films were developed. The entire
autoradiograms were analyzed for radioactivity using an
image processing system (MCID, Imaging Research, St.
Catharings, Canada). The optical density values were
converted to tissue reactivity using the Kety-Sokoloff
equation [7].
2.4. Measurement of O2 Delivery
Adjacent frozen samples from fourteen brain regions
were immediately used to determinate arterial and ve-
nous O2 saturation. Detail techniques have been pub-
lished previously [11]. Briefly, 20 μm sections were ob-
tained on themicrotome-cryostat at –35˚C under a N2
atmosphere. The sections were transferred to precooled
glass slides and covered with degassed silicone oil and a
cover slip. The slides were placed on a microspectro-
photometer fitted with an N2-flushed cold stage to obtain
readings of optical densities at 568, 560, and 506 nm.
This three-wavelength method corrects for the light scat-
tering in the frozen blood. Only vessels in the transverse

C.- T. HSIEH ET AL.
190
section were studied so that the path of light traversed
only the blood, Readings were obtained to determine O2
saturation in these regions. The O2 content of blood was
determined by multiplying the percent O2 saturation by
the hemoglobin concentration times 1.36.
2.5. Statistics
All data was presented with means ± SEM and statisti-
cally calculated by unpaired, two-tails t test.
3. Results
Hemodynamic and physiological data including plasma
glucose level, HCT, pH, pulse rate, weight, systolic
blood pressure, diastolic blood pressure, mean blood
pressure in two groups revealed no significant difference
(Table 1). According to the relevant data of blood gas, a
significant hyperoxemia (pO2 from 87.1 to 97 torrs, p <
0.05) was demonstrated, but the pCO2, the volume of O2
and the saturation of O2 did not reach the significant dif-
ferences.
LCBF at 14 brain structures was presented in Table 2.
Only the LCBF at basal ganglia was increased from 108
ml/min/100 g in the SCG group to 118 ml/min/100 g in
the sham-operated group. The others 13 brain structures
showed a decreased level of LCBF. The average of
LCBF was 150 ml/min/100 g in the sham-operated group
and 129 ml/min/100 g in the SCG group. A mean of 14%
reduction of LCBF was found at 14 brain structures.
However, these changes of LCBF at these 14 brain
structures did not reach the significant differences.
The delivery amount of O2 was also measured at 14
brain structures and summarized in Table 3. In 14 brain
structures, the delivery amount of O2 was all decreased,
except in basal ganglia. The differences in the delivery
amount of O2 between sham-operated and symphathec-
tomized group was not significantly meaningful in these
14 brain structures.
4. Discussion
Sympathetic nerves supply different parts of the cere-
brovascular system including the main pial arteries at the
base of the brain, the pial arterial and venous systems of
the convexities, and parts of the intracerebral (parenchy-
mal) vascular system [12]. Using the techniques of im-
munofluorescence and histofluorescence, cerebral vessels
have been proved to be innerved by peripheral sympa-
thetic nervous system, mainly arising from the ipsilateral
Table 1. Hemodynamic and physiologic al data in experimental rats under sham operation and SCG.
HCT HgB pH pCO2 pO2 O
2 vol. O2 sat.
Sham operation 49.91 ± 0.48 14.93 ± 0.09 7.41 ± 0.03 40.67 ± 1.56 87.1 ± 0.55 0.201 ± 0.001 96.47 ± 0.23
SCG 49.6 ± 0.93 14.42 ± 0.27 7.4 ± 0.02 38 ± 1.48 97 ± 3.94* 0.2 ± 0.001 97.2 ± 0.37
SBP DBP MBP PR Wt Glucose
Sham operation 143.33 ± 2.11 101.67 ± 4.01 115.56 ± 3.23 363.33 ± 17.26 318.67 ± 20.49 104.17 ± 24.67
SCG 139.17 ± 5.13 104.83 ± 3.93 116.28 ± 3.87 365 ± 16.88 335.33 ± 23.33 98.67 ± 5.77
*: significant difference between sham operation and SCG group in room temperature (two tailed, unpaired-t test), P < 0.05, values are means ± SEM. HCT:
hematocrit; HgB: hemoglobin; pH, pCO2, pO2: blood gas; O2 vol.: O2 volume; O2 sat.: O2 saturation; SBP: systolic blood pressure; DBP: diastolic blood pres-
sure; MBP: mean arterial blood pressure; PR: pulse rate; Wt: weight.
Table 2. Local cerebral blood flow (ml/min/100gm) at 14 brain structures in rats underwent sham operation and SCG in
room temperature.
Forebrain
FC SMC TC OC BG HIP Thalamus Hypo
Sham operation 234 ± 38 239 ± 40 125 ± 23 190 ± 27 108 ± 22 119 ± 14 151 ± 15 120 ± 15
SCG 191 ± 15 203 ± 13 107 ± 12 182 ±17 118 ±21 95 ± 6 133 ± 9 93 ± 8
Rostral hindbrain Caudal hindbrain
SC IC Midbrain Pons Medulla Vermis
Sham operation 166 ± 25 155 ± 30 133 ± 14 117 ± 12 102 ± 10 135 ± 17
SCG 126 ± 8 138 ± 8 103 ± 7 117 ± 27 83 ± 4 108 ± 6
Values are means ± SEM. FC: frontal cortex; SMC: sensorimotor cortex; TC: temporal cortex; OC:occipital cortex; BG: basal ganglia; HIP: hippocampus;
HYPO: hypothalamus; SC: superior colliculus; IC: inferior colliculus.

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191
Table 3. O2 delivery (ml/min/100gm) at 14 brain structures in rats underwent sham operation and SCG in room temperature.
Forebrain
FC SMC TC OC BG HIP Thalamus Hypo
Sham operation 47 ± 8 48 ± 8 25 ± 4 38 ± 5 22 ± 4 24 ± 3 30 ± 3 24 ± 3
SCG 38 ± 3 40 ± 2 21 ± 2 36 ± 3 23 ± 4 19 ± 1 26 ± 2 18 ± 2
Rostral hindbrain Caudal hindbrain
SC IC Midbrain Pons Medulla Vermis
Sham operation 33 ± 5 31 ± 6 27 ± 3 24 ± 2 20 ± 2 27 ± 3
SCG 25 ± 2 27 ± 2 20 ± 1 23 ± 5 17 ± 1 21 ± 1
Values are means ± SEM. FC: frontal cortex; SMC: sensorimotor cortex; TC: temporal cortex; OC:occipital cortex; BG: basal ganglia; HIP: hippocampus;
HYPO: hypothalamus; SC: superior colliculus; IC: inferior colliculus.
superior cervical ganglion [13]. These nerve fibers are
distributed mainly in rostral areas of the brain and het-
erogeneously distributed to cortical vessels to the level of
arterioles [5]. The innervation also provides a protective
mechanism for brain to insure an adequate O2 supply to
caudal regions under hypoxic conditions by limiting flow
to cortical areas [6].
Several studies about sympathetic influences on cere-
bral vessels have been discussed, especially in SCG, by
measuring the cerebral blood volume (CBV) and re-
gional CBF. Eklof et al. discovered CBF reduced about
30% in monkeys undergo bilateral SCG within 2 weeks
but the same results were not observed by Waltz et al in
the cat after monolateral SCG [14, 15]. Several experi-
mental studies revealed the various stages of CBV de-
pended on the time following bilateral SCG [12, 16, 17].
In serial mice studies, Edvinsson et al. found, compared
with sham-operated controls, CBV was decreased to a
level 15% to 28% below the control values twelve hours
after SCG, increased to a level 15% to 34% above the
control values one day later, and returned to normal
range within only one week [12,16]. He hypothesized the
vasoconstriction was caused by norepinephrine leakage
from the degenerating nerves shortly after operation;
vasodilatation resulted from a consequence of disap-
pearance of the transmitter one day later; and normaliza-
tion of vascular tone was caused by supersensitivity of
denervated vascular receptors to circulating catechola-
mines in chronic phase [12].
However, in the studies emphasized on the long term
effects (8 - 10 weeks) of unilateral SCG on non-anesthe-
tized rabbits, Aubineau et al. [18], found a mean of 17%
reduction of CBF compared to the heterolateral cortex.
This phenomenon was observed from 8 to 30 days after
the operation. Intravenous infusion of noradrenaline did
not significantly modify CBF in both hemispheres. There
were no signs of supersensitivity to catecholamines.
They concluded that, as in the peripheral circulation,
chronic sympathectomy affects the equilibrium of the
vascular smooth muscle fibers, but that circulating
amines play no compensatory role in the cerebral circu-
lation because of the blood-brain barriers. So the reduc-
tion of CBF could be attributed to many factors after
sympathectomy: decrease in the thickness of the turnica
media of the cerebral vessels [19], a modification of
membrane mechanisms of the smooth muscle fibers [20],
depolarization without any possible modification in the
threshold of excitability, a hypersensitivity to calcium
ion, and possible metabolic changes revealed by a de-
crease in sodium-potassium-adenosine triphosphatase
activity and modification in the level of adenosine
triphosphate [18]. Suppression of the whole cervical
sympathetic innervation could also result in a reduction
in pineal gland activity [21], alterations in the numerous
neuroendocrine systems [22], or a modification in the
activity of the carotid sinus [23]. Some of these phe-
nomena may modify CBF and CBV in the long term.
In our present study, two weeks postoperatively, the
bilateral SCG rats displayed a mean of 14% reductive
level of LCBF as compared to those of the sham-oper-
ated rats. In the 14 brain structure, the LCBF was all de-
creased, except in the basal ganglia. It showed the
subacute effect of bilateral SCG was not only in the CBF,
but also in the LCBF. The delivery amount of O2 was
also decreased in these regions. Our results were com-
patible with previous reports [11,18]. Based on these
results, we could conduct the study to investigate the
further effect of bilateral SCG in the rats with heat
stroke.
5. Conclusions
Although the change of LCBF and local cerebral O2 de-
livery in the 14 brain structure didn’t show the signifi-
cant differences, our present results show that subacute
effect (two weeks) of bilateral SCG on CBF was not only
in a decrease of LCBF, but also a decrease of local cere-
bral O2 delivery. About 14% decrease level of LCBF was

192 C.- T. HSIEH ET AL.
observed
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