Contralateral Superior Cervical Ganglion Research Articles

The effects of anti-nerve growth factor on retrograde labelling of superior cervical ganglion neurones projecting to the molar pulp in the rat

The aims were to demonstrate sympathetic ganglion neurones projecting to the rat molar pulp and to determine whether deprivation of nerve growth factor (NGF) in neonatal rats eliminates this source of pulpal innervation. Newborn Sprague-Dawley rats were given subcutaneous injections of rabbit anti-mouse-NGF serum for 1 month. Control animals included litter mates treated with preimmune serum and untreated, age-matched rats. At 4 months of age, Fluoro-gold (FG) was applied to the pulp chamber of the right first maxillary molar. One week later, the animals were perfusion fixed, and the superior cervical ganglia (SCG) were removed, embedded in paraffin, and serially sectioned at 10 μm. FG-labelled cells were detected by epifluorescence microscopy with a u.v. filter set. Control animals had 5–10 FG-labelled neurones widely distributed throughout the SCG ipsilateral to the injection site and no labelled cells in the contralateral SCG. NGF-deprived animals had either no FG-labelled cells or a single labelled cell in the ipsilateral SCG. These results indicate that, in rats, (1) the number of SCG neurones projecting to the molar pulp is rather low, (2) SCG neurones that innervate the dental pulp of the maxillary molar pulp are dispersed throughout the ganglion, (3) the projection from SCG to the molar is exclusively ipsilateral, and (4) neonatal NGF deprivation induces a permanent, almost total, loss of sympathetic neurones projecting to the dental pulp.

Increased Expression of Galanin in the Rat Superior Cervical Ganglion after Pre- and Postganglionic Nerve Lesions

Using immunohistochemistry the expression of galanin (GAL) and galanin message-associated peptide (GMAP) in the superior cervical ganglion (SCG) was investigated 2, 4, 7, and 14 days after unilateral transection of the cervical sympathetic trunk (decentralization) or after cutting the external and internal carotid nerves (axotomy), as well as 7 days after removal of parotid gland tissue. In control SCGs including the sympathetic trunk and the carotid nerves, very few neurons and fibers were GAL/GMAP-positive. Two and 7 days after decentralization, about 5% of all counted neuron profiles in the ipsilateral SCG were GAL/GMAP immunoreactive. Immunoreactive cell bodies were distributed throughout the SCG, with a greater number in the most caudal portion of the ganglion. Many GAL/GMAP-positive nerve fibers were observed in the whole SCG, with strongly fluorescent bundles of immunoreactive fibers accumulated at the caudal end of the SCG. Several GAL /GMAP-immunoreactive nerve fibers were seen ipsilaterally in the external carotid nerve, whereas only a few positive fibers could be observed in the internal carotid nerve. About 2% of all counted neuron profiles in SCGs ipsilateral to decentralization still contained GAL/GMAP-immunoreactivity 14 days after the operation. The number of GAL/GMAP-positive cell bodies was at least doubled in the contralateral SCGs after decentralization compared to controls. After axotomy, about 50% of all counted neuron profiles were GAL/GMAP-positive in the ipsilateral SCG and distributed throughout the SCG. A strong accumulation of immunoreactive nerve fibers was observed in both the internal and external carotid nerves. The number of GAL/GMAP-positive cell bodies was slightly increased in the contralateral SCGs. After unilateral removal of parotid gland tissue, many GAL/GMAP-positive cell bodies and some fibers were observed in the caudal half of the ipsilateral SCG. The number of immunoreactive nerve fibers was increased also in the external carotid nerve, but not in the internal carotid nerve. In situ hybridization revealed prepro GAL mRNA in about 5% of all SCG neuron profiles in decentralized SCGs, paralleling the increase seen in GAL/GMAP peptide content. There was also a small increase in prepro VIP mRNA-positive cells in the caudal part of the SCG. The present results indicate that both pre- and postganglionic lesions increase the content of GAL/GMAP in the SCG, with a much more pronounced increase after transection of the carotid nerves.

Neuropeptide Y inhibits sympathetic neurotransmission in ipsilaterally innervated but not contralaterally reinnervated superior tarsal smooth muscle of the rat

The superior tarsal smooth muscle (STM), which elevates the upper eyelid, normally is innervated by sympathetic neurons from the ipsilateral superior cervical ganglion that are not neuropeptide Y-immunoreactive (NPY-ir). Following neonatal ganglionectomy, this target is reinnervated by sympathetic nerves from the contralateral superior cervical ganglion that are strongly NPY-ir. We examined the effects of exogenously administered NPY on STM tone, response to norepinephrine, and sympathetic neurotrans-mission in ipsilaterally innervated and contralaterally reinnervated STMs. NPY (2–10 μg/kg iv) increased blood pressure but did not alter STM tone. Similarly, contractile responses to co-administered norepinephrine were not affected. These findings imply an absence of direct and indirect postjunctional actions of NPY on STM. Contractions elicited by stimulation of the cervical sympathetic nerve (1.5 Hz) were not affected by NPY on the contralaterally reinnervated side; however, ipsilateral contractions were decreased in a dose-dependent fashion, with an inhibition of about 40% at 10 μg/kg. We conclude that while the STM is unresponsive to exogenously administered NPY, this peptide exerts selective inhibitory effects on the ipsilateral NPY-ir-negative but not the contralateral NPY-ir-positive innervation. This suggests that the neonatally denervated STM is reinnervated by contralateral fibers that are functionally different from the normal ipsilateral innervation in being devoid of functional prejunctional NPY receptors.

Plasticity of the sympathetic nervous system innervating the cerebral arteries in rats

In order to investigate the neuroplasticity of the peripheral sympathetic nervous system innervating the cerebral blood vessels, we observed and traced the sprouting nerve fibers originating in the contralateral superior cervical ganglion (SCG) into the previously denervated cerebral arteries following unilateral excision of the SCG and/or decentralization of the contralateral SCG in young rats (4 weeks old). These nerve fibers were labeled anterogradely with wheat germ aggulutinin-horseradish peroxidase or stained immunohistochemically with anti-tyrosine hydroxylase antibody. Eight weeks after the right SCG excision, reinnervating nerve fibers originating in the contralateral ganglion formed a circular pattern of nerve plexus only on the wall of the main cerebral arteries of the circle of Willis in the ganglionectomized side. However, the decentralization of the contralateral SCG, which was performed simultaneously with a unilateral SCG excision, prevented the nerve sprouting into the denervated regions. Unilateral decentralization of SCG itself failed to affect their distribution pattern or their density of nerve fibers originating in the ganglion. It is concluded that in the young rat the outgrowth of the sympathetic nerve fibers into the denervated cerebral arteries was strongly impeded by the disconnection of ganglion cells from the central nervous system, while the decentralization alone could not affect the innervation pattern of the postganglionic fibers which have been already built-up in the cerebral arterial system.

Effects of hydrocephalus on the sympathetic nerves of cerebral arteries, investigated with WGA-HRP anterograde tracing in the rat

The effects of hydrocephalus on the plexus of sympathetic nerves of the intracranial vessels were investigated using wheat germ agglutinin combined with horseradish peroxidase (WGA-HRP). Hydrocephalus was induced by injection of kaolin into the cisterna magna of rats. Three weeks later the superior cervical ganglion (SCG) of one side received WGA-HRP. Three days later the circle of Willis and the contralateral superior cervical ganglion were dissected out. The intensity of labelling and density on the cerebral vessels and the number of labelled neurons on the contralateral superior cervical ganglion were calculated. The intensity of labelled nerves and thick bundles were significantly decreased, although tracing the nerve fibers throughout the length of the vessels was possible. The number of labelled neurons in the contralateral superior cervical ganglion indicated that the injection technique of WGA-HRP into the ganglion was correct in all rats. These results are in favour of the assumption, that the hydrocephalus related incomplete adrenergic denervation of the sympathetic perivascular nerve plexus was mainly due to neuropraxia of the nerve fibers rather than anatomical interruption of the axons.

Patterns of reinnervation of denervated cerebral arteries by sympathetic nerve fibers after unilateral ganglionectomy in rats

In order to clarify the manner in which previously denervated cerebral arteries become reinnervated after unilateral excision of the superior cervical ganglion (SCG), we observed directly the reinnervating sympathetic nerve fibers originating in the contralateral SCG by using anterograde labeling with wheat germ aggulutinin-horseradish peroxidase in rats. The nerve fibers sprouted from the nerve fibers in the contralateral anterior cerebral artery and reinnervated the arterial wall of the anterior cerebral artery of the denervated side as early as one week after ganglionectomy. In addition to this sprouting route, three other reinnervating nerve fiber routes were observed in the circle of Willis of the denervated side two weeks after ganglionectomy: the proximal portion of the internal carotid artery, the route passing between bilateral ethmodial arteries, and the posterior communicating artery. Eight weeks after ganglionectomy, these reinnervating nerve fibers formed a fairly dense plexus in a circular pattern in the circle of Willis. However, the reinnervation could not be observed in the arterial branches derived from the circle of Willis (middle cerebral artery and posterior cerebral artery) even 16 weeks after ganglionectomy. The present results clearly demonstrated the time course, distribution pattern and limitation of the reinnervation from the contralateral SCG following unilateral ganglionectomy. The fact that reinnervation could be observed only in the main cerebral arteries of the circle of Willis, in which the nerve plexus appeared to have a circular pattern, suggests a difference between the qualities of sympathetic innervation controlling the cerebral circulation in these arteries and the other arterial branches related to these differences in reinnervation capacity.

Sprouting of aberrant neuropeptide Y-immunoreactive sympathetic nerves into neonatally denervated smooth muscle

Sympathetic nerves normally project ipsilaterally to lateral cranial targets. Following unilateral superior cervical ganglionectomy in neonatal rats, however, neurons from the contralateral superior cervical ganglion sprout into the denervated region. In the present study we examined neuropeptide Y immunoreactivity (NPY-ir) of neurons comprising ipsilateral (control) and denervation-induced contralateral pathways to the superior tarsal smooth muscle of the eyelid. Fluoro-Gold injection of the control muscle retrogradely labelled 133 ± 18 neurons in the ipsilateral superior cervical ganglion; of these, 21 ± 3% displayed detectable NPY-ir. Fluoro-Gold injections of the reinnervated muscle labelled 20 ± 4 neurons in the contralateral superior cervical ganglion, of which 85 ± 3% contained detectable NPY-ir. Examination of the control tarsal muscle revealed DBH-ir noradrenergic nerves throughout the muscle and vasculature, while NPY-ir nerves were present primarily around blood vessels. In the reinnervated preparation, NPY-ir fibers innervated both blood vessels and tarsal muscle in a pattern similar to that of DBH-ir innervation. Acute excision of the remaining superior cervical ganglion eliminated all DBH-ir fibers bilaterally; NPY-ir was reduced markedly in the reinnervated preparations, though some fibers remained. We conclude that, following neonatal denervation, the tarsal muscle is reinnervated by a subpopulation of sympathetic neurons that differs in neuropeptide phenotype from that of the normal ipsilateral innervation.

Appearance of retrogradely labeled neurons in the rat superior cervical ganglion after injection of wheat-germ agglutinin-horseradish peroxidase conjugate into the contralateral ganglion

Injection of wheat-germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the superior cervical ganglion (SCG) of the rat results in accumulation of WGA-HRP in sympathetic postganglionic neurons in the contralateral SCG. The sympathetic pathways involved and the mechanism underlying the labeling were investigated. The labeling in neurons in the contralateral SCG was apparent 6 h after injection and increased in intensity with longer survival times. The number of labeled neurons reached 1300 at 72 h after the injection. Transection of the external (ECN) or internal carotid nerves (ICN) resulted in considerable reduction in the number of labeled neurons. Combined transection of both ECN and ICN virtually eliminated labeling in the contralateral SCG. This provides strong evidence that these two nerves are the major pathways for WGA-HRP transport out of the SCG. No labeling was observed in the contralateral SCG following injection of horseradish peroxidase (HRP). Therefore, it seems unlikely that a direct nerve connection exists between the bilateral ganglia. Instead, the labeling of contralateral SCG neurons appears to depend on the transneuronal transport capacity of WGA-HRP, which conveys the marker in an anterograde direction along the postganglionic fibers to terminals in sympathetic target organs, and then delivers it transneuronally to contralateral SCG neurons. We suggest that the sympathetic nerve fibers originating in the bilateral SCGs run intermingled and are in close contact in their peripheral target organs.

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.

Intracranial trajectories of sympathetic nerve fibers originating in the superior cervical ganglion in the rat: WGA-HRP anterograde labeling study

Intracranial trajectories of sympathetic nerve fibers originating in the superior cervical ganglion (SCG) in the rat were investigated by means of anterograde labeling following the injection of wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the unilateral SCG. The trajectory of the sympathetic fiber innervating the pineal gland and its continuing structures was found advancing along the abducent nerve, through the cavernous plexus, then along the trochlear nerve. Labeled sympathetic fibers showed two patterns of distribution in the blood vessels on the basal surface of the brain. The sympathetic fibers originating in the unilateral SCG were intermingled with those fibers from the contralateral SCG in the pineal gland, its continuing structures and the choroid plexus of the third ventricle as well as in the cerebral blood vessels.

Intraocular herpes simplex virus injection in neonatal rats induces sympathetic nerve cell destruction: Effect of nerve growth factor

The effect of herpes simplex virus (HSV) injection on the sympathetic nerve system of newborn rats was studied at structural, ultrastructural and immunohistochemical levels. It was found that HSV injected into the anterior eye chamber is retrogradely transported and reaches the nerve cell bodies of the ipsilateral superior cervical ganglion (SCG) after 18–24 hr, causing complete cell destruction within 3–4 days. In subsequent days, nerve cells of the contralateral SCG, spinal sensory ganglia, chromaffin cells and brain cells also become infected and are eventually killed by the virus. Pretreatment with nerve growth factor (NGF) produces an initial protection from viral cell destruction, but does not block the final, lethal effect of the virus. These investigations demonstrate that sympathetic nerve cell destruction can be induced in newborn rodents by HSV and that NGF treatment renders the cells, for a time-limited period, more resistant to the virus.

Secretion of parotid acinar granules in rats during reflex stimulation after chronic sympathectomy.

After chronic post-ganglionic sympathectomy the ultrastructure of 'resting' parotid acinar cells in rats remains relatively normal, despite the loss of nerve impulses normally causing secretion of acinar granules from this gland. The question whether eating hard chow still induces some acinar degranulation weeks after superior cervical ganglionectomy, has now been tested. It was found that scattered pockets of parotid acinar degranulation did occur. Some of these changes after unilateral denervation may have been attributable to intact sympathetic nerves arising from the contralateral superior cervical ganglion (Alm, Asking, Emmelin & Gjörstrup, 1984), but this cannot explain similar changes that occurred in glands after bilateral ganglionectomy. The possibility that some degranulation may be induced by circulating catecholamines was tested, 9-16 weeks after unilateral sympathectomy, by placing animals in the cold (0-4 degrees C) for 2 h before removal of tissues. Animals not given food during that time showed no evidence of parotid acinar degranulation, but those given hard chow showed extensive acinar degranulation in both parotid glands. On the sympathectomized side the degranulation was, however, less uniform and more patchy than on the side with an intact innervation. These findings agree with he belief that circulating catecholamines can, at times, induce degranulation of parotid acinar cells made supersensitive by chronic sympathetic denervation but, for it to occur, the cells must also be receiving parasympathetic stimulation at the same time. This interaction probably permits a sufficient turnover of granules to maintain a relative homoeostasis of the parotid acinar cells in rats.

Compensatory changes in contralateral sympathetic neurons of the superior cervical ganglion and in their terminals in the pineal gland following unilateral ganglionectomy

The sympathetic noradrenergic neurons of the rat superior cervical ganglia (SCGs) provide the major source of innervation to the pineal gland. The present study sought to determine if this sympathetic innervation can undergo collateral sprouting following partial denervation of the pineal by unilateral removal of the SCG (ganglionectomy), and whether such growth of axon terminals is associated with biochemical changes in the contralateral SCG. In the pineal gland following partial denervation, residual noradrenergic terminals underwent compensatory changes indicative of collateral sprouting, as evidenced by: a rapid reduction in tyrosine hydroxylase (TH) activity and in [3H]norepinephrine (NE) uptake, to about 50% of control by 2 days, which was followed by a gradual but sustained increase to levels of approximately 80% of control by 10 days and a reduction in the intensity and density but not in the distribution of fibers containing NE-induced fluorescence by 2 days, which was followed by a sustained increase. In the contralateral SCG, choline acetyltransferase (CAT) activity, a marker of cholinergic preganglionic terminals, was transiently increased to about 115% of control by 4 days and returned to control levels by 14 days after unilateral ganglionectomy; later, TH activity in noradrenergic cell bodies was gradually increased to about 140% of control by 10 days where it remained for up to 52 days. Unilteral ganglionectomy combined with decentralization of the contralateral SCG by preganglionic nerve cut prevented the compensatory changes in noradrenergic nerve terminals within the pineal.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid recovery of pineal function after partial denervation: a possible role for heteroneuronal uptake of transmitter in modulating synaptic efficacy

The pineal gland is innervated by sympathetic neurons whose cell bodies are located in the two superior cervical ganglia and whose axons reach the gland via the two internal carotid nerves (ICNs). Bilateral decentralization of the superior cervical ganglia, produced by lesioning both cervical sympathetic trunks (CSTs), abolishes the circadian rhythm in the activity of the pineal enzyme serotonin N-acetyltransferase (NAT). We have examined the effects on NAT activity of unilaterally cutting the ICN or the CST. During the first night after either operation, nocturnal NAT activity was reduced by 75% compared to controls. However, during the second night after unilaterally cutting the ICN, NAT activity was restored to control values, and normal enzyme activity was seen in these lesioned animals for up to 1 month after this operation. On the other hand, following unilateral decentralization of one superior cervical ganglion, enzyme activity was reduced for at least 5 months. The high enzyme activity in animals with one ICN cut was abolished by cutting the contralateral CST, indicating that the recovery of NAT activity depended on the remaining intact sympathetic neurons. Electrical stimulation of the intact ICN during the daytime in animals in which the contralateral ICN was cut produced an increase in pineal NAT activity which was greater than the increase seen when similar stimulation was performed in sham-operated animals or in animals in which the contralateral superior cervical ganglion had been decentralized. The time course of the recovery of nocturnal NAT activity after unilateral denervation of the pineal gland was similar to the time course of the decrease in norepinephrine uptake sites in the gland.(ABSTRACT TRUNCATED AT 250 WORDS)