Left Superior Cervical Ganglion Research Articles

Preliminary study on the role and mechanism of IL-6 receptor antagonists in improving post-infarction ventricular arrhythmia

Objective: To investigate the effect of tocilizumab (TCZ) on ventricular arrhythmias (VAs) after myocardial infarction (MI) in Sprague-Dawley rats and explore its potential mechanism. Methods: The random number table method was used to divide 32 adult male Sprague-Dawley rats into 4 groups: Sham group, TCZ group, MI group and MI+TCZ group, with 8 rats in each group. The MI model was established by ligation of the left anterior descending branch of the coronary artery in the MI and MI+TCZ groups, and only sutured without ligation in the Sham and TCZ groups. TCZ was injected into the left superior cervical ganglion (SCG) of rats in the TCZ and MI+TCZ groups after successful modeling or sham operation, and the same amount of normal saline was injected in the Sham and MI groups. 24 h after successful modeling, ECG of rats in each group was recorded, heart rate variability (HRV, including low frequency power (LF), high frequency power (HF), LF/HF ratio), QT interval, QTc interval were calculated, and left ventricular effective refractory period (ERP) and VA inducibility were measured. Myocardial infarct size and tissue changes were observed with triphenyl tetrazolium chloride staining and HE staining. Real-time PCR analysis was used to detect the messager RNA (mRNA) expression of interleukin-6 (IL-6) and signal transducer and activator of transcription (STAT) 3 in SCG and potassium voltage-gated channel subfamily D member 2 (Kcnd2) in myocardial infarction periphery. The expression of c-fos in SCG was detected by immunofluorescence staining. Results: Compared with Sham group and MI+TCZ group, rats in MI group had higher LF and LF/HF ratio, longer QT interval and QTc interval, more VAs induced, lower HF and shorter ERP (P all<0.05). Triphenyl tetrazolium chloride staining and HE staining showed that rats in the Sham and TCZ groups had normal myocardial tissue structure, those in the MI group had severe myocardial injury, and those in the MI+TCZ group had less myocardial injury than those in the MI group. Real-ime PCR analysis showed that compared with Sham group and MI+TCZ group, mRNA expression levels of IL-6 and STAT3 in SCG of rats in MI group were higher, and mRNA expression level of myocardial Kcnd2 was lower (P all<0.05). Immunofluorescence staining showed that the content of c-fos in SCG of rats in MI group was higher than that of Sham group and MI+TCZ group (P all<0.05). Conclusions: TCZ may reduce neural activity of the SCG after MI by inhibiting the IL-6/STAT3 signaling pathway, thereby alleviating myocardial injury and inhibiting VAs.

No Evidence of Neurogenesis in Adult Rat Sympathetic Ganglia Following Guanethidine-Induced Neuronal Loss.

The potential for neurogenesis in the cranial (superior) cervical ganglia (SCG) of the sympathetic nervous system was evaluated. Eleven consecutive daily doses of guanethidine (100 mg/kg/d) were administered intraperitoneally to rats in order to destroy postganglionic sympathetic neurons in SCG. Following the last dose, animals were allowed to recover 1, 3, or 6 months. Right and left SCG from guanethidine-treated and age-matched, vehicle-treated control rats were harvested for histopathologic, morphometric, and stereologic evaluations. Both morphometric and stereologic evaluations confirmed neuron loss following guanethidine treatment. Morphometric analysis revealed a 50% to 60% lower number of tyrosine hydroxylase (TH)-positive neurons per unit area of SCG at both 3 and 6 months of recovery, compared to ganglia of age-matched controls, with no evidence of restoration of neuron density between 3 and 6 months. Reductions in TH-positive neurons following guanethidine treatment were corroborated by unbiased stereology of total hematoxylin and eosin-stained neuron numbers in SCG. Stereologic analyses revealed that total neuron counts were lower by 37% at 3 months of recovery when compared to age-matched vehicle controls, again with no obvious restoration between 3 and 6 months. Thus, no evidence was found that postganglionic neurons of the sympathetic nervous system in the adult rat have a neurogenic capacity.

Superior Cervical Ganglionectomy alters Glomus Cell Potassium‐Channel Properties in Response to Hypoxia

The carotid body (CB) chemosensory glomus (type I) cells respond to changes in blood PO2, PCO2, and pH by releasing neurotransmitters that increase action potential discharge of chemosensory afferent fibers within the carotid sinus nerve (CSN). The CSN then signals to the nucleus tractus solitarius (NTS) within the dorsal brainstem, which leads to a compensatory increase in ventilation in order to restore blood gas levels and pH. Along with the CSN, the ganglioglomerular nerve (GGN) also innervates the carotid body. The GGN consists of post‐ganglionic sympathetic fibers, which originate from the superior cervical ganglion (SCG). Stimulation of the GGN causes an increase in CB chemosensory afferent discharge. However, it is unknown whether loss of sympathetic input to the CB directly alters the chemosensitivity of glomus cells. Our objective was to characterize electrophysiological properties of CB glomus cell potassium (K+) channels in response to acute hypoxia following superior cervical ganglionectomy (SCGx). Sprague Dawley (SD) male rats postnatal (P) 21 were subjected to unilateral (right) SCGx. The left SCG was identified, but not removed. Four days post surgery at P25 the right and left carotid bodies were removed, and primary glomus cells were isolated and plated on coverslips. Glomus cell K+ channel properties were then recorded using the whole‐cell perforated patch‐clamp technique. Our preliminary results reveal that following unilateral (right) SCGx, glomus cells respond to hypoxia with significant reductions (P&lt;0.05 to P&lt;0.01) in outward K+ current amplitudes over the test potential range +10 to +60 mV. The mean maximal effect, a reduction in K+ amplitude of 64.9 ± 18.5% (mean ± SD, n = 3 cells), occurred at a Vtest of +30 mV. In contrast, wild‐type control CB glomus cells respond to hypoxia with a significant reduction (P&lt;0.05) in outward K+ current amplitude at only a Vtest of +60 mV (n = 4 cells). In addition, glomus cells from SCGx rats appear to respond to hypoxia via a different population of K+ channels that do not appear to be presently active in wild‐type glomus cells when exposed to hypoxia. These findings demonstrate that loss of sympathetic input from the SCG increases CB glomus cell sensitivity to hypoxia, and modulates the O2‐sensing capabilities of glomus cell K+ channels.Support or Funding InformationNIH‐SPARC 1OT2OD023860‐02 SJLewisThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Local sympathetic denervation attenuates myocardial inflammation and improves cardiac function after myocardial infarction in mice.

AimsCardiac inflammation has been suggested to be regulated by the sympathetic nervous system (SNS). However, due to the lack of methodology to surgically eliminate the myocardial SNS in mice, neuronal control of cardiac inflammation remains ill-defined. Here, we report a procedure for local cardiac sympathetic denervation in mice and tested its effect in a mouse model of heart failure post-myocardial infarction.Methods and resultsUpon preparation of the carotid bifurcation, the right and the left superior cervical ganglia were localized and their pre- and postganglionic branches dissected before removal of the ganglion. Ganglionectomy led to an almost entire loss of myocardial sympathetic innervation in the left ventricular anterior wall. When applied at the time of myocardial infarction (MI), cardiac sympathetic denervation did not affect acute myocardial damage and infarct size. In contrast, cardiac sympathetic denervation significantly attenuated chronic consequences of MI, including myocardial inflammation, myocyte hypertrophy, and overall cardiac dysfunction.ConclusionThese data suggest a critical role for local sympathetic control of cardiac inflammation. Our model of myocardial sympathetic denervation in mice should prove useful to further dissect the molecular mechanisms underlying cardiac neural control.

Vasoactive Intestinal peptide modulates c-Fos activity in the trigeminal nucleus and dura mater mast cells in sympathectomized rats.

Neurogenic inflammation in the dura mater caused by trigeminal nociceptive activation has been implicated in the pathophysiology of migraine. Vasoactive intestinal polypeptide (VIP) is a powerful neuroprotective neuropeptide that can modulate mast cell behavior. Migraine is also associated with sympathetic insufficiency. This study investigates the effects of VIP on the number of mast cells in the dura mater and on c-Fos expression in the trigeminal nucleus of sympathectomized rats. Experiments were carried out with 32 Sprague-Dawley male rats with body weights of 200-250 g. In the sympathectomized group, the left superior cervical sympathetic ganglion was removed. In the sympathectomized + VIP group, postoperative VIP 25 ng/kg/day (0.2 ml) was administered for 5 days. In the sham group, the ganglion and nerves were exposed but not dissected. Dura maters were stained with toluidine blue, and brainstems were labeled by indirect immunohistochemistry for c-Fos. Sympathectomy significantly increased the number of mast cells in both the ipsilateral and the contralateral dura mater (P < 0.001). VIP decreased the number of mast cells in both sides of the dura mater in sympathectomized rats. VIP also decreased c-Fos expression in the ipsilateral trigeminal nucleus of sympathectomized rats (P < 0.001). In the context of an experimental superior cervical ganglionectomy model of migraine, VIP is an efficient modulator of neurogenic inflammation of the dura.

Origins and neurochemical complexity of preganglionic neurons supplying the superior cervical ganglion in the domestic pig.

The superior cervical ganglion (SCG) is a center of sympathetic innervation of all head and neck organs. SCG sympathetic preganglionic neurons (SPN) were found in the nucleus intermediolateralis pars principalis (IMLpp), the nucleus intermediolateralis pars funicularis (IMLpf), the nucleus intercalatus spinalis (IC), and the nucleus intercalatus spinalis pars paraependymalis (ICpe). Despite its importance, little is known of SCG innervation and chemical coding in the laboratory pig, a model that is physiologically and anatomically representative of humans. Here in our study, we established the distribution and chemical coding of Fast Blue (FB) retrogradely labelled SPN innervating porcine SCG. After unilateral injection of FB retrograde tracer into the left SCG, labeled neurons were found solely on the ipsilateral side with approximately 98 % located in Th1–Th3 segments and predominantly distributed in the IMLpp and IMLpf. Neurochemical analysis revealed that approximately 80 % of SPN were positive both to choline acetyltransferase (ChAT) and nitric oxide synthase (NOS) and were surrounded by a plethora of opioidergic and peptiergic nerve terminals. The results of our study provide a detailed description of the porcine preganglionic neuroarchitecture of neurons controlling the SCG, setting the stage for further studies concerning SPN plasticity under experimental/pathological conditions.

Cervical Ganglion Block Attenuates the Progression of Pulmonary Hypertension via Nitric Oxide and Arginase Pathways

It has been recognized that the sympathetic nervous system is activated in pulmonary arterial hypertension (PAH), and abnormal sympathetic hyperactivity leads to worsening of PAH via endothelial dysfunction. The purpose of this study was to examine whether sympathetic ganglion block (SGB) can treat PAH by increasing the availability of nitric oxide (NO). PAH was induced in rats by 50 mg/kg of subcutaneous monocrotaline. After 2 weeks, daily injections of ropivacaine into the left superior cervical ganglion were repeated for 14 days (monocrotaline-SGB group). Monocrotaline group received sham SGB with saline, whereas control group received saline instead of monocrotaline. PAH was evident in monocrotaline group, with right ventricular systolic pressures (47±4 mm Hg) that were higher than those of controls (17±2 mm Hg), whereas SGB significantly attenuated monocrotaline-induced PAH (35±4 mm Hg). The right/left ventricular mass ratios exhibited similar changes to those seen with right ventricular pressures. Heart rate variability showed significantly higher sympathetic activity in the monocrotaline group. Microscopy revealed a higher proportion of muscular arteries with thicker medial walls in the monocrotaline group, which was attenuated by SGB. Monocrotaline induced arginase hyperactivity, which was in turn decreased by SGB-induced endothelial NO synthase activation. SGB restored monocrotaline-induced hypoactivity of superoxide dismutase. In conclusion, SGB could suppress PAH and the remodeling of pulmonary arteries via inactivation of arginase and reciprocal elevation of NO bioavailability, thus attenuating disproportionate hyperactivation of the sympathetic nervous system.

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Introduction: It has been recognized that the sympathetic nervous system is activated in pulmonary arterial hypertension (PAH), and abnormal sympathetic hyperactivity leads to worsening of PAH via endothelial dysfunction. The purpose of this study was to examine whether sympathetic ganglion block (SGB) can treat PAH by increasing the availability of nitric oxide (NO). Methods: Male Sprague-Dawley rats were allocated into 3 groups that received daily injections of 0.1 ml of saline (control and monocrotaline (MCT) groups) or 0.25% ropivacaine (SGB-MCT group) into the left superior cervical ganglion for 28 days after subcutaneous administration of saline (control group) or 50 mg/kg of MCT (MCT and SGB-MCT groups). Heart rate variability was recorded to assess autonomic activity. Right ventricular systolic pressure and hypertrophy were evaluated after sacrifice. Lung tissue NO synthase, arginase, and oxidative stress were examined. Microscopic exam was done to evaluate pulmonary arterial hypertrophy. Results: PAH was evident in the MCT group, with right ventricular systolic pressures (47 ± 11 mmHg) that were higher than those of controls (17 ± 5 mmHg), while SGB significantly attenuated MCT-induced PAH (28 ± 4 mmHg). The right/left ventricular mass ratios exhibited similar changes to those seen with right ventricular pressures. Heart rate variability showed significantly higher sympathetic activity in the MCT group. Additionally, microscopy revealed a higher proportion of muscular arteries with thicker medial walls in the MCT group, which was attenuated by SGB. MCT also induced arginase hyperactivity, which was in turn decreased by SGB-induced endothelial NO synthase activity. SGB restored hypoactivity of superoxide dismutase and increased malondialdehyde and nitrotyrosine induced by MCT. Conclusions: SGB could suppress PAH and the remodeling of pulmonary arteries via inactivation of arginase and reciprocal elevation of NO bioavailability, thus attenuating disproportionate hyperactivation of the sympathetic nervous system.

Hypertrophy and neuron loss: structural changes in sheep SCG induced by unilateral sympathectomy

Recently, superior cervical ganglionectomy has been performed to investigate a variety of scientific topics from regulation of intraocular pressure to suppression of lingual tumour growth. Despite these recent advances in our understanding of the functional mechanisms underlying superior cervical ganglion (SCG) growth and development after surgical ablation, there still exists a need for information concerning the quantitative nature of the relationships between the removed SCG and its remaining contralateral ganglion and between the remaining SCG and its modified innervation territory. To this end, using design-based stereological methods, we have investigated the structural changes induced by unilateral ganglionectomy in sheep at three distinct timepoints (2, 7 and 12 weeks) after surgery. The effects of time, and lateral (left-right) differences, were examined by two-way analyses of variance and paired t-tests. Following removal of the left SCG, the main findings were: (i) the remaining right SCG was bigger at shorter survival times, i.e. 74% at 2 weeks, 55% at 7 weeks and no increase by 12 weeks, (ii) by 7 weeks after surgery, the right SCG contained fewer neurons (no decrease at 2 weeks, 6% fewer by 7 weeks and 17% fewer by 12 weeks) and (iii) by 7 weeks, right SCG neurons were also larger and the magnitude of this increase grew substantially with time (no rise at 2 weeks, 77% by 7 weeks and 215% by 12 weeks). Interaction effects between time and ganglionectomy-induced changes were significant for SCG volume and mean perikaryal volume. These findings show that unilateral superior cervical ganglionectomy has profound effects on the contralateral ganglion. For future investigations, it would be interesting to examine the interaction between SCGs and their innervation targets after ganglionectomy. Is the ganglionectomy-induced imbalance between the sizes of innervation territories the milieu in which morphoquantitative changes, particularly changes in perikaryal volume and neuron number, occur? Mechanistically, how would those changes arise? Are there any grounds for believing in a ganglionectomy-triggered SCG cross-innervation and neuroplasticity?

The Developing Left Superior Cervical Ganglion of Pacas (Agouti paca)

In this study the main question investigated was the number and size of both binucleate and mononucleate superior cervical ganglion (SCG) neurons and, whether post-natal development would affect these parameters. Twenty left SCGs from 20 male pacas were used. Four different ages were investigated, that is newborn (4 days), young (45 days), adult (2 years), and aged animals (7 years). By using design-based stereological methods, that is the Cavalieri principle and a physical disector combined with serial sectioning, the total volume of ganglion and total number of mononucleate and binucleate neurons were estimated. Furthermore, the mean perikaryal (somal) volume of mononucleate and binucleate neurons was estimated using the vertical nucleator. The main findings of this study were a 154% increase in the SCG volume, a 95% increase in the total number of mononucleate SCG neurons and a 50% increase in the total volume of SCG neurons. In conclusion, apart from neuron number, different adaptive mechanisms may coexist in the autonomic nervous system to guarantee a functional homeostasis during ageing, which is not always associated with neuron losses.

Asymmetric post-natal development of superior cervical ganglion of paca (Agouti paca)

Functional asymmetry has been reported in sympathetic ganglia. Although there are few studies reporting on body side-related morphoquantitative changes in sympathetic ganglion neurons, none of them have used design-based stereological methods to address this issue during post-natal development. We therefore aimed at detecting possible asymmetry-related effects on the quantitative structure of the superior cervical ganglion (SCG) from pacas during ageing, using very precise design-based stereological methods. Forty (twenty left and twenty right) SCG from twenty male pacas were studied at four different ages, i.e. newborn, young, adult and aged animals. By using design-based stereological methods the total volume of ganglion and the total number of mononucleate and binucleate neurons were estimated. Furthermore, the mean perikaryal volume of mononucleate and binucleate neurons was estimated, using the vertical nucleator. The main findings of this study were: (1) the right SCG from aged pacas has more mononucleate and binucleate neurons than the left SCG in all other combinations of body side and animal age, showing the effect of the interaction between asymmetry (right side) and animal age, and (2) right SCG neurons (mono and binucleate) are bigger than the left SCG neurons (mono and binucleate), irrespective of the animal age. This shows, therefore, the exclusive effect of asymmetry (right side). At the time of writing there is still no conclusive explanation for some SCG quantitative changes exclusively assigned to asymmetry (right side) and those assigned to the interaction between asymmetry (right side) and senescence in pacas. We therefore suggest that forthcoming studies should focus on the functional consequences of SCG structural asymmetry during post-natal development. Another interesting investigation would be to examine the interaction between ganglia and their innervation targets using anterograde and retrograde neurotracers. Would differences in the size of target organs explain ganglia structural asymmetry?

Sympathectomy does not affect the early ectopic discharge from myelinated fibres in ferret inferior alveolar nerve neuromas

Ectopic neural activity from damaged axons is thought to contribute to the development of sensory disorders following nerve injury. Here we have studied the role of sympathetic fibres in the generation or potentiation of this abnormal activity by determining the effect of predegenerating these fibres. Twelve adult ferrets were used in the study and six of them underwent sympathectomy by removal of the left superior cervical ganglion. Electrophysiological recordings were made from myelinated axons in fine filaments dissected from the inferior alveolar nerve, 3 days after it had been ligated further distally, and the level of spontaneous activity and mechanical sensitivity was determined. There was no significant difference between the level or characteristics of spontaneous activity, or the level of mechanical sensitivity, in the two groups of animals. We conclude that, in this animal model, the absence of sympathetic nerve fibres does not affect the development or characteristics of ectopic neural activity in the early period following nerve injury.

Autoregulation of cochlear blood flow in the hydropic guinea pig

Previous data suggest that regulation of cochlear blood flow (CBF) may be abnormal in the hydropic guinea pig. The purpose of this study was to employ the technique of anterior inferior cerebellar artery (AICA) occlusion to measure CBF autoregulation in experimental endolymphatic hydrops. This study also addresses the role of the cochlear sympathetic neural innervation and nitric oxide in CBF regulation with hydrops. In anesthetized guinea pigs, CBF was measured with a laser Doppler flowmeter probe while the AICA was intermittently occluded with a microvascular occluder. The CBF response was measured in normal, 6-week, and 12-week chronically hydropic animals. The gain factors (0 = no autoregulation, 1 = complete autoregulation) for 1-min occlusion were 0.95 ± 0.16 (control), 0.77 ± 0.28 (6 week, P = 0.164), and 0.67 ± 0.25 (12 week, P = 0.037). N G-nitro- l-arginine methyl ester ( l-NAME), a competitive inhibitor of nitric oxide synthase, was infused intravenously to assess basal nitric oxide (an endogenous vasodilator) production in the hydropic ear. With infusion of l-NAME, CBF was reduced by 9.16 ± 11%, 10.7 ± 10% ( P = 0.87), and 16.6 ± 18% ( P = 0.95), in the control, 6-week, and 12-week animals, respectively. In a separate group of 12-week hydropic animals, the left superior cervical ganglion (SCG) was anesthetized with lidocaine, and AICA occlusions were performed pre-and post-blockade. Prior to blocking the SCG, the gain was 0.712 ± 0.02 and afterwards 0.708 ± 0.051 ( P = 0.93). The above results show that there was a statistically significant reduction in CBF autoregulation in the 12-week hydropic animals. There was no difference in basal nitric oxide production in normal versus hydropic animals nor was there a change in autoregulation following blockade of the SCG. These data provide clear evidence for reduced CBF autoregulation in experimental endolymphatic hydrops.

Reduction of synthetic and mitotic activity in the wool follicle by catecholamines

Literature evidence on the effects of catecholamines on wool growth is scant and the short-term effects have not been investigated. Since catecholamines are relatively short-lived, three approaches were adopted to investigate their effects on cellular events in the wool follicle over periods as short as 4 h. In vitro culture of skin revealed a reduction of DNA synthesis in response to either adrenaline or noradrenaline added to the media (P &lt; 0.001) in a dose-dependent manner (P &lt; 0.001). Intradermal injections of adrenaline and noradrenaline significantly lowered the rate of cell division in wool follicles in comparison with control sites in vivo (P &lt; 0.05). These results indicate that the catecholamines can rapidly lower the rate of proliferative events in the wool follicle. The left superior cervical ganglion was removed from 18 sheep. The animals were exposed to a cold environment and ear temperature was monitored to indicate the likely release of noradrenaline in the skin of the cheeks or adrenaline from the adrenals. With respect to the sympathectomized side, a reduction in ear temperature on the unoperated side was associated with lowered mitotic rate at the unoperated cheek site (P &lt; 0.026). However, when the temperature of the unoperated side was not lowered, mitotic rate was not consistently lower on one side with respect to the other. Physiological levels of noradrenaline therefore mimicked the effects observed during the pharmacological studies, and the catecholamines may therefore play an important role in the regulation of wool growth.

Effects of renal denervation and reinnervation on ganglionic gene expression of neurotransmitter proteins and c- fos in rat

To investigate the molecular basis for reno-renal interactions, Northern blot analyses of sympathetic ganglia were used to study the changes in levels of mRNA encoding tyrosine hydroxylase (TH), neuropeptide Y (NPY), and c- fos at 4, 14, 21, and 56 days after denervation of the left kidney, and of c- fos mRNA at 1 and 4 h after denervation. Ganglia included in the study were right and left paravertebral chain ganglia (PVG, T 11 to L 2), celiac-mesenteric plexus (CMP), and right and left superior cervical ganglia (SCG). Levels of TH mRNA in the left PVG and CMP were decreased at 4 and 14 days compared to controls. Levels were elevated at 21 days and similar to control levels at 56 days. In the right PVG, TH mRNA levels were elevated at 4 and 14 days, diminished from this elevated level at 21 days, and similar to control levels at 56 days. No differences were found in TH mRNA levels of left or right SCG compared to controls. In long-term experiments (days), no differences in NPY or c- fos mRNA levels were found in any of the ganglia from experimental rats compared to controls. Levels of c- fos mRNA in the left PVG and CMP were decreased at 1 hour compared to control levels. By 4 h, differences in mRNA levels were no longer apparent. In the right PVG, c- fos mRNA levels were elevated at 1 hour and no longer different from control levels at 4 h. No differences were found in c- fos mRNA levels of left or right SCG compared to controls. We conclude that kidney denervation leads to acute and chronic decreases in ipsilateral ganglionic levels of c- fos and TH mRNAs, respectively, and that levels of TH mRNA return to normal only after reinnervation presumably occurs. We also conclude that unilateral denervation causes reflex increases in gene expression of c- fos and TH in the PVG innervating the contralateral kidney. Data obtained for c- fos gene expression indicate that these reflex changes have an early onset and data for TH gene expression indicate that they continue to operate until the compromised kidney is reinnervated.

ネコ一側反回神経, 上喉頭神経切断による両側内喉頭筋の筋電図学的, 形態学的変化について

One Year after transection of the left superior and recurrent laryngeal nerves of cats reflex arcs between the internal branch of the right superior laryngeal nerve and the left intrinsic laryngeal muscles were recognized electromyographically. Possible participation of the right recurrent laryngeal nerve, the bilateral vagosympathetic trunks, and the left superior cervical ganglion and nodose ganglion was suggested. Moreover, the reflex arcs between the internal branch of the right superior laryngeal nerve and the right, intact intrinsic laryngeal muscles were recognized despite the transection of the right recurrent laryngeal nerve. At the neuromuscular junctions of the right, intact intrinsic laryngeal muscles an increase in the size of postsynaptic area devoid of nerve terminals was observed.

Effects of Stimulation of the Superior Cervical Ganglia and Local Application of Noradrenaline on Electrical Activity of the Syrian Hamster Pineal Gland

Abstract The effects of electrical stimulation of either or both superior cervical ganglia and the effects of local application of L-noradrenaline on the spontaneous electrical activity of hamster pineal cells were evaluated. Extracellular recordings from pineals of anaesthetized hamsters revealed that the spontaneous electrical activity was mainly regular with interspike intervals attributed between 12 to 20 ms during the daytime and mainly irregular with interspike intervals of 1 to 250 ms during the night. Following stimulation of the superior cervical ganglia, either unilaterally or bilaterally, or local application of noradrenaline, the responses of these pineal cells fell into three major categories: A) non-responsive, B) excited, and C) inhibited. There was no relationship between the magnitude or form of response and the source of stimulus i.e. the right superior cervical ganglia or the left superior cervical ganglia. Almost all inhibited responses from electrical stimulation of the superior cervical ganglia could be correlated with inhibited responses from the local application of noradrenaline whereas excited responses could not. In general, these results suggest that the spontaneous electrical activity of some pineal cells is influenced by inputs from the superior cervical ganglia and that the inhibitory input is likely to be mediated through the release of noradrenaline. The excitatory input from the superior cervical ganglia is probably mediated by another neurotransmitter. The heterogeneity of responses suggests that different receptors or different cell types may be involved.

Sympathetic sprouting into neonatally denervated contralateral target: superior cervical ganglion neuronal numbers and sizes

Unilateral superior cervical ganglionectomy results in establishment of an atypical functional projection from the contralateral ganglion to the denervated superior tarsal muscle in neonatal but not in juvenile or adult rats. Previous studies of peripheral nervous system development have attributed enhanced neuroplasticity to either formation of pathways by surplus cells rescued from cell death (hypothanasia-induced hyperplasia), or more vigorous terminal arborization of neurons innervating adjacent target zones (collateral sprouting with associated somatic hypertrophy). In the present study, experiments were performed to determine if neonatal sympathetic sprouting to contralaterally denervated target is associated with superior cervical ganglion neuronal hyperplasia or hypertrophy. Fluoro-Gold injections of right superior tarsal muscle in adult rats following neonatal ganglionectomies labelled cells in the contralateral superior cervical ganglion, whereas cells were labelled strictly ipsilaterally in sham operates. Profile areas of contralaterally projecting neuronal somata were twice as large as those providing ipsilateral innervation. Ganglion volumes, neuronal nuclear diameters and packing densities, and total neuronal numbers in left superior cervical ganglia of animals receiving neonatal right superior cervical ganglionectomy were comparable to those of both right and left ganglia of sham-operated controls. It is concluded that establishment of a contralateral projection does not rescue significant numbers of neurons from naturally occurring cell death. Rather, contralateral sprouting derives from neurons showing pronounced somatic hypertrophy.

Sympathetic innervation of the supratentorial dura mater of the rat

The origin, density, and distribution of sympathetic nerve fibers in the supratentorial dura mater of the rat were examined in detail in the current study by using wheat germ agglutinin horseradish peroxidase (WGA-HRP) retrograde tracing procedures, glyoxylic acid-induced fluorescence, and dopamine beta-hydroxylase (DBH) immunocytochemical staining of dural whole mount preparations. Application of WGA-HRP to the superior sagittal sinus and adjacent areas of the supratentorial dura mater labeled numerous neurons in each of the left and right superior cervical ganglia. Glyoxylic acid and DBH immunocytochemical staining of fixed dural whole mount preparations revealed prominent plexuses of sympathetic nerves about the middle meningeal artery and its branches, about the superior sagittal and transverse sinuses, and "free" within the dura mater, i.e., apparently unassociated with any vasculature. Significantly, in all of these areas, the density of sympathetic innervation revealed in this study was considerably greater than that previously demonstrated by other workers. An impressive population of mast cells also was observed within the dura mater of the glyoxylic acid-treated preparations. The majority of these cells were perivascular; however, a significant number were also present within the dura unrelated to the vasculature, and occasional cells were seen in close apposition to fluorescent sympathetic nerve fibers. Taken together, the identification of a robust sympathetic plexus and prominent mast cell population associated with a dura mater that also receives significant sensory projections from the trigeminal system raises interest regarding the functional interactions of these elements. These observations warrant further consideration regarding their role in the pathogenesis of vascular headache and head pain.

Morphometric and histological analysis of the superior cervical ganglion in experimental Chagas' disease in rats.

Histological methods were used for studying the left superior cervical ganglia of control and T. cruzi infected female rats killed 13, 20, and 34 days after inoculation. Concomitantly, the sympathetic innervation of the heart auricular appendages and of the submandibular gland was studied by a glyoxylic acid-induced fluorescence method for catecholamines. At day 34 of infection, the superior cervical ganglia of an additional group of control and infected animals were studied morphometrically through the determination of ganglion volume, total number, and nuclear diameter of the principal neurons. No amastigote pseudocyst could be detected inside the ganglia at any time during infection. Inflammatory reactions were very discrete or absent at day 13 of infection, but were clearly present at day 20 as periganglionitis (in all infected animals) or ganglionitis (in 62.5% of the infected animals). These reactions again became very discrete at day 34 of infection. None of the morphometric parameters analyzed were altered by Chagas' disease. Histochemical studies on the sympathetic innervation of the heart and submandibular gland showed disappearance or rarefaction of fluorescent nerve fibers, starting around the 13th day of infection. The involvement of sympathetic nerve terminals in Chagas' disease is a local phenomenon rather than a consequence of parasitism or destruction.