Target-dependent plasticity of galanin and vasoactive intestinal peptide in the rat superior cervical ganglion after nerve lesion and re-innervation.

The expression of the neuropeptides galanin and vasoactive intestinal peptide (VIP) is increased in subpopulations of sympathetic neurons after axotomy of the rat superior cervical ganglion. We investigated whether postganglionic neurons innervating different targets show a prevalence for any of the two peptides in response to carotid nerve lesion. Before the respective postganglionic axons were crushed close to the ganglion, postganglionic neurons projecting either to the iris (through the internal carotid nerve) or to the submandibular gland (through both carotid branches) were identified by the retrograde tracer Fast Blue. Galanin and VIP immunoreactivities were demonstrated two and 30 days after crush and after successful regeneration of the lesioned neurons (60 days). In control ganglia, both peptides were detected in a few gland- but not in iris-projecting neurons. However, two days after crush of the respective carotid nerves, 14% of neurons within the iris and 46% within the gland population were immunoreactive for galanin. The percentage of neurons immunoreactive for VIP was significantly lower in both populations: only 3.5% of neurons projecting to the iris and 23% of the gland-projecting neuron population exhibited this peptide. After 30 days, the percentage of galanin- and VIP-positive neurons projecting to the submandibular gland was reduced (24% and 5.7%, respectively), whereas the proportion of galanin-immunoreactive neurons further increased within the iris population (55%), indicating that some neurons express galanin at later stages after the lesion. At 60 days after the crush, the percentage of galanin- or VIP-immunoreactive neurons had decreased to control levels within those neuron populations that re-innervated the iris or submandibular gland, although the total number of neurons exhibiting galanin or VIP was still increased within the ganglion, suggesting that re-establishment of target contact may play a role in down-regulation of both peptides.

The sensory and sympathetic innervation of guinea-pig lung and trachea as studied by retrograde neuronal tracing and double-labelling immunohistochemistry.

The sympathetic and sensory innervation of guinea-pig trachea and lung were studied by means of retrograde neuronal tracing using fluorescent dyes, and double-labelling immunofluorescence. Sympathetic neurons supplying the lung were located in stellate ganglia and in thoracic sympathetic chain ganglia T2-T4; those supplying the trachea resided in the superior cervical and stellate ganglia. Retrogradely labelled sympathetic neurons were usually immunoreactive to tyrosine hydroxylase; the majority also contained neuropeptide Y immunoreactivity. However, a small number were non-catecholaminergic (i.e. tyrosine hydroxylase negative), but neuropeptide Y immunoreactive. Within the airways, tyrosine hydroxylase/neuropeptide Y-immunoreactive axons were found in the smooth muscle layer, around blood vessels including the pulmonary artery and vein, and to a lesser extent in the lamina propria. Periarterial axons contained in addition dynorphin immunoreactivity. Sensory neurons supplying the lung were located in jugular and nodose vagal ganglia as well as in upper thoracic dorsal root ganglia; those supplying the trachea were most frequently found bilaterally in the nodose ganglia and less frequently in the jugular ganglia. A spinal origin of tracheal sensory fibres could not be consistently demonstrated. With regard to their immunoreactivity to peptides, three types of sensory neurons projecting to the airways could be distinguished: (i) substance P/dynorphin immunoreactive; (ii) substance P immunoreactive but dynorphin negative; and (iii) negative to all peptides tested. Substance P-immunoreactive neurons innervating the airways invariably contained immunoreactivity to neurokinin A and calcitonin gene-related peptide. Retrogradely labelled neurons located in the nodose ganglia belonged almost exclusively (greater than or equal to 99%) to the peptide-negative group, whereas the three neuron types each represented about one-third of retrogradely labelled neurons in jugular and dorsal root ganglia. Within the airways, axons immunoreactive to substance P/neurokinin A and substance P/calcitonin gene-related peptide were distributed within the respiratory epithelium of trachea and large bronchi, in the lamina propria and smooth muscle from the trachea down to the smallest bronchioli (highest density at the bronchial level), in the alveolar walls, around systemic and pulmonary blood vessels, and within airway ganglia. Those axons also containing dynorphin immunoreactivity were restricted to the lamina propria and smooth muscle. The origin of nerve fibres immunoreactive for vasoactive intestinal polypeptide, of which a part were also neuropeptide Y immunoreactive, could not be determined by retrograde tracing experiments. Vasoactive intestinal polypeptide-immunoreactive fibres terminating within airway ganglia may be of preganglionic parasympathetic origin, whereas others (e.g. those found in smooth muscle) may arise from intrinsic ganglia.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical heterogeneity of nerve cells in the human adrenal gland with special reference to substance P.

Neurons in the human adrenal medulla, stained by the NADH-diaphorase reaction, were counted and their neurochemical markers were investigated by double labeling immunofluorescence with special reference to substance P. The findings indicate a significant participation of intramedullary nerve cell bodies in human adrenal innervation with 40.4 neurons/mm3 adrenal medulla. Substance P-immunoreactive neurons, which made up approximately 20% of all neurons, exhibited heterogeneity by co-localization of immunoreactivities for dynorphin, for cholecystokinin, and for neurofilament triplet. Substance-P-immunolabeled neurons were always nonreactive for calcitonin gene-related peptide, for vasoactive intestinal polypeptide, or for tyrosine hydroxylase, the rate-limiting enzyme of catecholamine synthesis. These chemical phenotypes of intramedullary neurons reveal immunohistochemical similarities with postganglionic neurons in parasympathetic ganglia or with enteric neurons, suggesting a hitherto unrecognized functional significance of the intrinsic nervous system in the human adrenal gland.

Expression of nicotinic acetylcholine receptors in the rat superior cervical ganglion on mRNA and protein level.

The expression of nicotinic acetylcholine receptors (nAChR) in the rat superior cervical ganglion was investigated by Western blotting, immunohistochemistry and non-radioactive in situ hybridization applying probes for the alpha 4-1 and beta 2 subunit mRNA. Immunoblot analysis of homogenized ganglia using the anti-nAChRs antibody WF6 revealed a labeled protein band of apparent molecular weight of 40 kDa which is typical for the alpha subunit of nAChRs. Applying double-labeling immunofluorescence with antibodies against tyrosine hydroxylase, nAChR-like molecules were identified in most postganglionic neurons and in a subpopulation of small intensely fluorescent (SIF) cells. alpha 4-1 and beta 2 subunit mRNAs were detected in all perikarya of postganglionic sympathetic neurons but not in SIF cells. These results suggest that antibodies raised against purified Torpedo AChR bind to nAChR in sympathetic ganglia and indicate that alpha 4-1 and beta 2 subunits are constituents of nAChRs in sympathetic postganglionic neurons but not of SIF cells.

Calcitonin gene-related peptide (CGRP)-immunoreactive neurons in the human cervico-thoracic paravertebral ganglia.

The occurrence of CGRP-immunoreactive neurons in human paravertebral sympathetic ganglia was investigated and CGRP-immunoreactive perikarya correlated with the distribution of structures which were immunoreactive to other peptides and tyrosine hydroxylase, the key enzyme of catecholamine-synthesis. CGRP-immunoreactive neurons were present in all investigated ganglia (superior cervical ganglion, stellate ganglion, thoracic ganglia IV and VII). Most of the CGRP-immunolabelled cell bodies contained also vasoactive intestinal polypeptide-as well as somatostatin-immunoreactivity. Approximately 40 per cent of the CGRP-immunoreactive neurons were weakly tyrosine hydroxylase-immunolabelled. CGRP-immunoreactive cell bodies appear to be neither identical with the large population of neuropeptide Y-labelled perikarya nor with the large group of cell bodies which were surrounded by leuenkephalin-immunoreactive nerve fibres. Colocalization of CGRP- with vasoactive intestinal polypeptide- and somatostatin-immunoreactivity in postganglionic sympathetic neurons substantiates the suggestion of sympathetic origin of respective peptidergic nerve fibres in sweat glands.

Immunohistochemical evidence for different opioid systems in the rat superior cervical ganglion as revealed by imipramine treatment and receptor blockade.

The distribution pattern of opioid-immunoreactive nerve cell bodies and varicose fibres in the rat superior cervical ganglion after chronic administration of the tricyclic antidepressant imipramine, various receptor blockades (muscarinic antagonist, atropine sulphate; opiate antagonist, naloxone; kappa-antagonist, MR2266BS), and denervation was investigated immunohistochemically using a biotin-streptavidin-peroxydase complex method. Antisera to four peptides derived from two different precursors of the opioid family were used. In control superior cervical ganglia sparsely scattered nerve fibres and no neuronal cell bodies were immunoreactive when antisera to dynorphin A (1-17) or alpha-neo-endorphin (cleavage products of prodynorphin) were applied. A moderate number of nerve fibres and neuronal perikarya were immunoreactive to antisera directed against met-enkephalin-arg-phe (cleavage product of proenkephalin) and leu-enkephalin (cleavage product of prodynorphin and proenkephalin); non-identical cell bodies contained met-enkephalin-arg-phe- or leu-enkephalin-immunoreactivity. After drug treatment specific changes in the immunoreactivity of the investigated peptides in the superior cervical ganglion were demonstrated. (a) Treatment with imipramine resulted in an increase of nerve fibres demonstrating immunoreactivity to antisera against dynorphin A and alpha-neoendorphin. In contrast, no alteration in the numbers of nerve fibers but a numerical increase of postganglionic cell bodies immunoreactive to either met-enkephalin-arg-phe or leu-enkephalin antisera was demonstrated. Moreover, some perikarya exhibited immunoreactivity to both these opioids. (b) Receptor blockade with the muscarinic antagonist atropine sulphate or the general opiate antagonist naloxone had no effect on the number and distribution of dynorphin A or alpha-neoendorphin immunoreactive fibres, whereas both met-enkephalin-arg-phe and leu-enkephalin-immunoreactive fibres and postganglionic perikarya were increased in number. (c) After the kappa antagonist (MR2266BS), an increase of fibres with prodynorphin-derived opioid immunoreactivity as well as those with met-enkephalin-arg-phe- or leu-enkephalin-immunolabelling was visible and the met-enkephalin-arg-phe and leu-enkephalin-immunoreactive cell bodies were increased in number. The preganglionic origin of the investigated fibres with prodynorphin cleavage products was concluded from the complete disappearance of such fibres after preganglionic denervation. Denervation also resulted in an increase of met-enkephalin-arg-phe- and leu-enkephalin-immunoreactive perikarya. Small intensely fluorescent (SIF) cells, which in controls were nonrea

Secretoneurin-immunoreactivity in nerve terminals apposing identified preganglionic sympathetic neurons in the rat: colocalization with substance P and enkephalin.

Preganglionic sympathetic neurons projecting to the superior cervical ganglion are innervated by nerve fibers containing classical neurotransmitters as well as neuropeptides. In this study we examined the possible participation of a novel peptide, secretoneurin (a cleavage product of secretogranin II), in regulation of sympathetic outflow to head and neck by using a retrograde labelling-technique combined with immunohistochemistry. In addition, the coexistence of secretoneurin with substance P and leu-enkephalin, peptides known to innervate preganglionic neurons, was investigated. The majority of retrogradely labeled neurons were localized in the nucleus intermediolateralis of spinal cord segments T1-T3 (maximum at T2). Nearly all of Fast Blue positive neuronal perikarya were apposed by nerve fibers and terminals exhibiting immunoreactivity to secretoneurin. The main secretoneurin-immunoreactive form found in the upper thoracic segments corresponded to the free peptide secretoneurin as revealed by chromatography and radioimmunoassay. More than half of labeled neurons were surrounded by nerve endings containing in addition substance P or leu-enkephalin which were also, however, less frequently colocalized. Our results suggest that secretoneurin influences the activity of preganglionic sympathetic neurons projecting to the superior cervical ganglion. Regarding their frequent colocalization with substance P and leu-enkephalin, functional interactions of these peptides on preganglionic sympathetic nerve activity have to be considered.

Immunocytochemical correlates of an extrapituitary adrenocortical regulation in man.

Investigations reviewed in this article provide cytochemical and functional support for a significant involvement of extrapituitary factors in human adrenocortical functions. Among these factors neural messengers may play a crucial role in the adrenocortical regulation, arising from specifically coded postganglionic neurons with both, extrinsic and intrinsic locations, as well as from chemically characteristic afferent neurons. The close association of varicose transmitter segments with steroid hormone synthesizing cells and their occurrence at arteries and sinusoid capillaries are indicative for both direct and indirect regulatory mechanisms on cortical functions. The immunohistochemical presence of neuropeptides and cytokines in endocrine and/or immune cells of the human adrenal medulla and cortex as well as specific binding sites on steroidogenic cells indicate the modulatory implication of additional short-paracrine- and ultrashort-autocrine-feedback loops on cortical cell proliferation and steroid metabolism. The summarized data suggest that basal endocrine influence of the hypothalamo-pituitary axis on adrenocortical growth and functions in man is controlled by the nervous system that also regulates local fine-tuning of human cortical activity.

Localization, regulation and functions of neurotransmitters and neuromodulators in cervical sympathetic ganglia.

Cervical sympathetic ganglia represent a suitable model for studying the establishment and plasticity of neurochemical organization in the nervous system since sympathetic postganglionic neurons: (1) express several neuromediators, i.e., short acting transmitters, neuropeptide modulators and radicals, in different combinations; (2) receive synaptic input from a limited number of morphologically and neurochemically well-defined neuron populations in the central and peripheral nervous systems (anterograde influence on phenotype); (3) can be classified morphologically and neurochemically by the target they innervate (retrograde influence on phenotype); (4) regenerate readily, making it possible to study changes in neuromediator content after axonal lesion and their possible influence on peripheral nerve regeneration; (5) can be maintained in vitro in order to investigate effects of soluble factors as well as of membrane bound molecules on neuromediator expression; and (6) are easily accessible. Acetylcholine and noradrenaline, as well as neuropeptides and the recently discovered radical, nitric oxide, are discussed with respect to their localization and possible functions in the mammalian superior cervical and cervicothoracic (stellate) paravertebral ganglia. Furthermore, mechanisms regulating transmitter synthesis in sympathetic neurons in vivo and in vitro, such as soluble factors, cell contact or electrical activity, are summarized, since modulation of transmitter synthesis, release and metabolism plays a key role in the neuronal response to environmental influences.

Chemosensitivity, plasticity, and functional heterogeneity of paraganglionic cells in the rat coeliac-superior mesenteric complex.

Chemosensitivity and plasticity of paraganglionic cells in the rat coeliac-superior mesenteric complex (CSMC) were investigated at a basal state of normoxia (21% O2) and after long-term moderate hypoxia (10% O2, 14 days). Chemical sympathectomy previous to hypoxia was performed to destroy principal ganglionic neurons and thus to allow measurement of the norepinephrine and dopamine content of paraganglionic cells. At the basal state, the CSMC contained dopaminergic (TH+/DBH-) and noradrenergic (TH+/DBH+) paraganglionic cells, the majority being of the noradrenergic type. After 14 days of hypoxia, this ratio was reversed and dopaminergic cells predominated, as indicated by a twofold increase of TH+ cells and a twofold decrease of DBH+ cells. Biochemically, hypoxia produced an increase in the content (1.6-fold) and utilization (1.4-fold) of dopamine as well as a smaller increase in the content of norepinephrine, with no change in its utilization rate. The dopaminergic activation induced by hypoxia persisted after sympathectomy with guanethidine. It is concluded that paraganglionic cells in the CSMC display a chemosensitive function. Furthermore, our findings indicate that paraganglionic cells are differentially affected by hypoxia, depending on their distribution and the nature of their neuromodulators. The alterations induced by hypoxia point out the phenotypic plasticity developed by paraganglionic cells in adaptation to hypoxia and further demonstrate the functional heterogeneity of this autonomic cell population in the rat CSMC.

Immunohistochemistry of small intensely fluorescent (SIF) cells and of SIF cell-associated nerve fibers in the rat superior cervical ganglion.

Double-labelling immunofluorescence was applied on single sections of the rat superior cervical ganglion to evaluate neurochemistry and connectivity of intraganglionic SIF cells. The synaptic vesicle membrane protein synaptophysin and secretoneurin, a newly discovered neuropeptide derived from secretogranin II, proved reliable molecular markers of this cell type, whereas serotonin and tyrosine hydroxylase immunoreactivities were observed in slightly incongruent SIF cell subpopulations. Immunolabelling for vasoactive intestinal polypeptide and neuropeptide Y occurred in few SIF cells. None of the above immunoreactivities were visibly altered by preganglionic or postganglionic denervation, while some SIF cells were immunolabelled for galanin or for the neuronal microtubule-associated protein MAP2 after postganglionic denervation. SIF cells were nonreactive for the pan-neuronal marker protein gene product (PGP) 9.5 or neurofilament 160 kD. Intense staining of NADPH-diaphorase in some SIF cells, suggesting catalytic activity of nitric oxide synthase, could not be substantiated by immunoreactivity for this enzyme. SIF cells were approached by nonidentical fiber populations immunoreactive for PGP 9.5, neurofilament, or neuropeptide Y, whereas immunoreactivities for galanin and vasoactive intestinal polypeptide were colocalized in fiber meshes around SIF cells. The findings indicate (1) neurochemical SIF cell heterogeneity, (2) SIF cell plasticity in response to ganglionic perturbation, and (3) a differentiated innervation of SIF cells in the rat superior cervical ganglion.

Plasticity of postganglionic sympathetic neurons in the rat superior cervical ganglion after axotomy.

The neuropeptides galanin (GAL) and vasoactive intestinal polypeptide (VIP) are upregulated in spinal and vagal sensory as well as in cranial motor neurons after axonal transection. In this study an increase of both peptides is demonstrated in axotomized principal ganglionic neurons (PGN) of the rat sympathetic superior cervical ganglion by use of double-labeling immunofluorescence. Compared to control ganglia that do not contain more than 1% GAL- or VIP-positive cells, about 26% of all PGN exhibit GAL immunoreactivity by day 1 after transection of the major postganglionic branches. The proportion of immunoreactive neurons reaches its maximum after 30 days (40%) and decreases to about 27% within the second month after axotomy. The percentage of VIP-positive neurons is much lower than for GAL: 2% of the PGN exhibit VIP immunoreactivity at day 1 and about 7% are observed 30 and 60 days after axotomy. In order to further characterize newly GAL- and VIP-positive PGN, their cell diameters were determined 12 days after axotomy. Compared to the mean overall neuron diameter of 24.8 microns, GAL-immunoreactive neurons are predominantly of small and intermediate size (22.2 microns), whereas VIP occurs mainly in larger neurons (26.1 microns). Besides cell bodies, many intraganglionic nerve fibers stain positive for GAL or VIP, particularly at day 6. Most likely, these fibers represent axons, as indicated by the absence of MAP2, a cytoskeletal protein found in neuronal somata and dendrites. They establish direct membrane contacts with postganglionic perikarya, as revealed by pre-embedding immuno-electron microscopy. Some cell bodies and fibers contain both peptides. Colocalization of GAL or VIP with tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine synthesis, reveals a reduced immunoreactivity for TH in intensely GAL- or VIP-positive cells, and vice versa at day 6. However, no difference in staining intensity for VIP or GAL, and TH, is observed after 30 and 60 days. Possible implications of GAL and VIP for peripheral nerve regeneration and their regulation by target-derived factors are discussed.

PACAP immunoreactivity in the rat superior cervical ganglion in comparison to VIP.

The presence and regulation of pituitary adenylate cyclase activating peptide (PACAP) was investigated in the adult rat superior cervical ganglion. Double-labelling immunofluorescence using specific antibodies against PACAP and vasoactive intestinal peptide (VIP) revealed a dense innervation of postganglionic sympathetic neurones by PACAP-immunoreactive but VIP-negative nerve endings that mainly were of preganglionic origin since they disappeared after transection of the cervical sympathetic trunk. Since PACAP regulates transmitter synthesis and release in sympathetic neurones in vitro, this finding provides a morphological correlate for modulatory effects of PACAP in vivo. Few neurones contained PACAP under normal conditions. However, the number of PACAP-positive neurones increased in response to axotomy of the postganglionic nerves. Many of the newly PACAP-positive neurones also contained VIP, suggesting that both peptides are regulated by similar mechanisms.

Substance P-immunoreactive nerve fibers in tracheobronchial lymph nodes of the guinea pig: origin, ultrastructure and coexistence with other peptides.

Double-labeling immunofluorescence of guinea pig tracheobronchial lymph nodes revealed complete coincidence of SP and CGRP immunoreactivities in perivascular nerves and axons of the medullary lymphatic tissue. Additional dynorphin A or cholecystokinin immunoreactivity was seen only in some of the medullary fibers. Ultrastructurally, all SP-immunoreactive axons were unmyelinated and displayed vesicle-containing varicosities. Retrograde neuronal tracing combined with immunohistochemistry revealed a sensory origin from dorsal root ganglia of SP/CGRP-immunoreactive fibers ramifying within paratracheal lymph nodes, and an additional neuronal population being devoid of SP/CGRP immunoreactivity. The findings provide evidence for several types of sensory nerve fibers innervating lymph nodes.

Localization of vasoactive intestinal polypeptide-receptor-immunoreactivity in human salivary glands.

A monoclonal VIP-receptor antibody derived from a human adenocarcinoma cell line (HT 29) was used in combination with immunogold silver staining for the immunohistochemical demonstration of VIP-receptor (rec) immunoreactivity (IR) in paraffin-embedded human salivary glands (parotid, palatal, labial glands). VIP-rec-IR was localized to mucous endpieces of labial and--to a lesser extent--palatal glands, intercalated ducts of the parotid gland, and excretory ducts of all glands investigated. The findings correlate well with known effects of VIP on mucous release and electrolyte transport in salivary glands. Lack of VIP-rec-IR at serious acini may point to immunologically different receptor subtypes in these glands.

Biochemical analysis of catecholamines in small intensely fluorescent (SIF) cell clusters of the rat superior cervical ganglion.

The microlaser technique of isolating small cell clusters has been applied to groups of small intensely fluorescent (SIF) cells in rat superior cervical ganglion. Alternate cryostat sections were either incubated in glyoxylic acid monohydrate or freeze-dried. SIF cell clusters, recognized by glyoxylic acid-induced fluorescence, were re-identified in the consecutive freeze-dried section through dark-field microscopy. Three clusters were dissected with a BTG microlaser unit and collected for biochemical assay. The catecholamine content of the specimens was measured by gas chromatography/mass fragmentography, using 3 deuterated catecholamines as an internal standard and calibration curves of each catecholamine. The findings indicate the presence of these 3 catecholamines in rat SIF cell clusters in a varying amount: in probes, each consisting of 5 cell clusters, the content of norepinephrine averaged approximately 7.3 pmol, of epinephrine below 1 pmol, and of dopamine from below 1 pmol to 14.6 pmol.

Differential effects of noxious and non-noxious input on neurones according to location in ventral periaqueductal grey or dorsal raphe nucleus.

Nociceptive and non-nociceptive input to the dorsal raphe nucleus (DR) and to the surrounding periaqueductal grey (PAG) was studied in chloralose-anaesthetized rats. Single units in the midbrain responding to electrical stimulation of a coccygeal nerve were recorded with glass micropipettes. A fluorescence histochemical technique was applied to identify recording sites in the DR and PAG. 109 DR-units, 141 PAG-units and 95 units from surrounding structures were tested for responsiveness to electrical nerve stimulation. In 53% of the DR-units, but in only 20% of the PAG- and SN-units, ongoing activity was inhibited by electrical stimulation (I-units) while 42% of the PAG- and SN-units but only 24% of the DR-units were electrically excited (E-units). 40 E-units and 24 I-units were tested with repeated noxious radiant heat stimuli applied to the tail or hindpaws. 70% of the E-units were excited by heating, and in 54% of the I-units ongoing activity was inhibited by heating. The majority of the former units were located in the PAG, and most of the latter were proven to be DR-neurones. In 75% of the E-units and in 12.5% of the I-units the heat effect was in the opposite direction. The findings are discussed in terms of the now well-established role of the PAG-region in the descending control of pain. The properties of the PAG-E-units suggest that this system is involved in a negative feedback circuit by which pain transmission to the CNS limits itself. DR-I-units may be involved via an additional small loop with the PAG to disinhibit the activation of the PAG pain control system.

Immunofluorescent localization of dopamine-beta-hydroxylase in small intensely fluorescent cells of the rat superior cervical ganglion.

Serial sections of the superior cervical ganglion of newborn and adult rats have been treated alternatively with fluorescent labelled antibodies to dopamine-beta-hydroxylase ( (DBH), or with glyoxylic acid. Two different cell types could be distinguished: (1) a small intensely fluorescent (SIF)-cell majority demonstrating a bright glyoxylic acid-induced fluorescence but no DBH-positive fluorescence; (2) a minor cell population being fluorescent following both treatments. The findings indicate the presence of norepinephrine (and/or epinephrine)-containing SIF-cells in the rat superior cervical ganglion.

Different types of calcitonin gene-related peptide-immunoreactive neurons in the guinea-pig stellate ganglion as revealed by triple-labelling immunofluorescence.

A triple-labelling immunofluorescence technique was used to study the patterns of coexistence of calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), and tyrosine hydroxylase (TH) in the guinea-pig stellate ganglion. CGRP-immunoreactive postganglionic neurons, which all were of the non-catecholaminergic type, could be divided into NPY-positive and NPY-negative populations. Sweat glands, which are a known target of CGRP-immunoreactive sympathetic neurons, exhibited exclusively fibers of the CGRP+/NPY- phenotype. Lack of coexistence of CGRP- and NPY-immunoreactivity was also observed in nerves within skeletal muscle, brown adipose tissue and hairy skin. The findings document a previously unknown diversity of CGRP-immunoreactive postganglionic sympathetic neurons, and indicate the existence of an addition, presently unidentified target of non-catecholaminergic, CGRP-immunoreactive sympathetic neurons.

Vasoactive intestinal peptide but not galanin promotes survival of neonatal rat sympathetic neurons and neurite outgrowth of PC12 cells.

The synthesis of the neuropeptide galanin (GAL) is greatly enhanced after axonal lesion in different neuron populations of the peripheral and central nervous system. In sympathetic ganglia, GAL-immunoreactive nerve fiber baskets have been found surrounding postganglionic neurons after axotomy. Until now, it is unclear if GAL may be involved in neuronal survival or regeneration as suggested for vasoactive intestinal peptide (VIP) that is also upregulated after nerve lesion. We have, therefore, studied the effects of GAL on survival of sympathetic neurons dissociated from newborn rat superior cervical ganglia and on neurite outgrowth of PC12 cells. These effects were compared to those elicited by VIP. Whereas VIP promoted survival of about 10% of sympathetic neurons 2 days after nerve growth factor deprivation and induced neurite outgrowth of PC12 cells already at 6 h after addition of the peptide, GAL had no effect in either of these culture systems. While the induction of VIP may be beneficial for axotomized neurons, the functional significance of increased GAL levels remains to be established.