Evidence for GABAergic fibers entering the superior cervical ganglion of rat from the preganglionic nerve trunk

Summary The origin of gamma-aminobutyric acid immunoreactive (GABA-IR) nerve fibers present in the superior cervical ganglion (SCG) of rat was investigated. With immunocytochemical techniques many nerve fibers showed GABA-like positivity in the cervical sympathetic trunk, whereas similar staining could not be revealed in the internal carotid nerve or in the external carotid nerve. Ligation of the cervical sympathetic trunk for 24 h resulted a dramatic reduction in the staining density in the ganglion and in the cervical sympathetic trunk distal to the ligature. After transection of the preganglionic nerve fibers for eleven days or more, very few fibers staining for GABA were seen in the ganglion. The immunohistochemical results suggest that a major source of GABA within the SCG is a population of GABAergic axons entering from the preganglionic trunk.     

Convergence of preganglionic fibers on superior cervical ganglion neurons in the rabbit

Intracellular recording techniques were used to record electrical response from neurons of the rabbit (isolated) superior cervical ganglion to single stimuli applied to bundles of preganglionic fibers as well as tonic electrical neuronal activity in this ganglion during acute experiments in situ. A review of the findings obtained confirms that neurons of the ganglion receive preganglionic synaptic inputs of two types, the first of a single pattern, formed by a preganglionic fiber; excitatory action of the latter on ganglion units suffices to induce postsynaptic action potentials (AP I) and the second of a multiple pattern, formed by several preganglionic fibers with relatively faint excitatory action, capable of evoking postsynaptic action potentials (AP II) only when excited in unison. Interspike intervals for AP I and AP II in tonic neuronal activity conformed to a normal distribution and a random distribution pattern respectively.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 252–261, March–April, 1989.     

Vasopressin release from posterior pituitary lobe incubated in situ after preganglionic stimulation of the rat superior cervical ganglion.

In urethane-chloralose anaesthesia the pituitary gland was exposed by transpharyngeal approach in rats. The anterior lobe was removed and the posterior lobe was incubated in situ, that is in conditions of anatomical integrity of the hypothalamus with the posterior pituitary lobe. The 15-min samples of the medium incubating the posterior pituitary lobe in situ were collected. Vasopressin (AVP) content in the incubation medium was determined by radioimmunoassay. The stimulation of preganglionic fibers of the superior cervical ganglion (SCG) with alternate short (5 s) bursts of electric pulses with short (5 s) breaks did not change AVP release. However, stimulation of preganglionic fibres with alternate long (30 s) bursts of electric pulses with long (30 s) breaks evoked an increase in AVP release after some latency. Probably, at the hypothalamic or posterior pituitary level temporal summation should occur affecting vasopressinergic neurons or their endings and evoking AVP release.     

Transmission pathways in the rat superior cervical ganglion

On isolated preparations of the superior cervical ganglion (SCG, n = 8) taken from 21-day-old rats, we studied the intraganglion pathways and mechanisms underlying generation of synaptic responses of SCG neurons to antidromic stimulation. One of the three nerves connected with the SCG was stimulated, and compound action potentials were recorded simultaneously from the other two nerves; then, the order of stimulated and recorded nerves was changed. Orthodromic stimulation of the cervical sympathetic nerve (CSN) evoked responses in the internal carotid nerve (ICN), which could be completely blocked by hexamethonium, and responses in the external carotid nerve (ECN), which contained a component that was not blocked by this of the ECN caused responses in the CSN, which were not blocked by hexamethonium. Effects of superfusion of the SCG with a Ca²⁺-free solution allowed us to conclude that the hexamethonium-insensitive component of the responses in the CSN and ECN and ECN-CSN conduction can be explained by the presence of direct fibers going from the CSN to the ECN with no synaptic relay. Possible mechanisms underlying antidromic stimulation-induced synaptic responses in SCG neurons are discussed. Neirofiziologiya/Neurophysiology, Vol. 39, Nos. 4/5, pp. 396–399, July–October, 2007.     

Changes in the macrophage population of the rat superior cervical ganglion after postganglionic nerve injury

Following peripheral nerve transection, a series of biochemical changes occurs in axons and Schwann cells both at the site of lesion and distal to it. Macrophages differentiated from monocytes that invade the area in response to transection (elicited macrophages) and, perhaps, also macrophages normally present in the tissue (resident macrophages) play important roles in these changes. In addition, nerve transection produces changes in the cell bodies of axotomized neurons and their surrounding glial cells, located at some distance from the lesion. To determine whether macrophages might play a role in the changes occurring in the superior cervical ganglion (SCG) after axotomy, we examined the presence of macrophages before and after axonal damage. The monoclonal antibodies ED1, ED2, and OX6 were used, each of which recognizes a somewhat different population of macrophages. Ganglia from normal rats contained a population of resident cells that were ED2+ but very few that were ED1+. Within 2 days after the postganglionic nerves were transected, the number of ED1+ cells increased substantially, with little change in immunostaining for ED2. These data, in combination with published studies on other tissues, suggest that ED1 in the SCG is selective for elicited macrophages and ED2 for resident macrophages. OX6 immunostaining was prominent in normal ganglia but also increased significantly after axotomy, suggesting that it reflects both macrophage populations. Systemic administration of 6-hydroxydopamine, a neurotoxin that causes the destruction of sympathetic nerve endings, also produced an increase in ED1 immunostaining. Thus, the change in ED1 immunostaining in the SCG does not require surgery, with the attendant servering of local blood vessels and connective tissue, but rather only the disconnection of sympathetic neurons from their end organs. The time course of the invasion of monocytes after axotomy indicates that this process is not required to trigger the biochemical changes occurring in the ganglion within the first 24 h. On the other hand, the existence of a resident population of macrophages raises the possibility that changes in those cells might be involved. © 1995 John Wiley & Sons, Inc.     

Origins of the afferent fibers to the cat superior cervical ganglion.

The origins of the afferent fibers to the cat's superior cervical ganglion (SCG) were demonstrated by using the retrograde horseradish peroxidase tracing method. We found that the preganglionic neurons were located in the spinal segments C8-T5, particularly in T1-T3. These neurons were situated mainly in the intermediolateral column. The extra-SCG neurons along with the cervical sympathetic trunk originated ipsilaterally from the middle cervical and stellate ganglia, and contralaterally from the caudal part of the SCG. Labeled neurons also originated from the mandibular division of the trigeminal ganglion. Our results demonstrated that many fiber sources projected to the SCG, which plays a complicated synaptic role in controlling the visceral organs of the head and neck region.     

Synapses of the superior cervical ganglion of the white rat

In the complexe system of synapses in the white rat's superior cervical ganglion, authors show the existence of: 1 - somato-somatic neuronal synapses 2 - somatic synapses between S.I.F. cells 3 - recurrent auto-synapses They moreover mention widening of synaptic cleft of the synapses between S.I.F. cells and their processes.     

Evidence for transsynaptic regulation of neuronal cell surface heparan sulfate proteoglycan in developing rat superior cervical ganglion

The effect of neonatal deafferentation on the expression of a neuronal cell surface heparan sulfate proteoglycan (HeS-PG) was investigated in the developing rat superior cervical ganglion. Two monoclonal antibodies, one directed against the core protein of HeS-PG, and one to a determinant associated with a heparan sulfate side-chain, were used to monitor postnatal increases of HeS-PG by radioimmunoassay. Following neonatal deafferentation by section of the cervical sympathetic trunk, total protein per ganglion was slightly reduced at survival times of 7, 14, and 30 days. Expression of the core protein determinant on HeS-PG was not altered in deafferented ganglia. In contrast, levels of side-chain determinant were significantly reduced at 14 and 30 days. These results suggest that processing of HeS-PG side-chains by principal ganglionic neurons is partially regulated by transsynaptic influences during development. Transsynaptic regulation of neuronal development may be a more general process than was believed previously, with effects not limited to molecules associated with synaptic development.     

Transmitters and modulators in the superior cervical ganglion of the rat

Several transmitters and modulators have been found to exist in the superior cervical ganglion of the rat. It has been shown that noradrenaline is present in the principal neurons and dopamine is the main catecholamine in the small intensely fluorescent cells. 5-hydroxytryptamine and histamine have been investigated immunohistochemically and found to be present only in the small intensely fluorescent cells of an adult rat, in the same cells which are also immunoreactive to tyrosine hydroxylase. On the other hand, enkephalins which were studied using highly specific antibodies against methionine-enkephalin-arginine-phenylalanine and methionine-enkephalin-arginine-glycine-leucine were found in the principal neurons and nerve fibres. Ligation studies showed that enkephalins in the superior cervical ganglion of the rat are both of intrinsic and extrinsic origin. It is evident that the transmission in the sympathetic ganglion is complex. The possible function of the transmitter and modulator candidates is discussed.