Occurrence of vasoactive intestinal polypeptide (VIP)-like immunoreactivity in certain cholinergic neurons of the cat: evidence from combined immunohistochemistry and acetylcholinesterase staining

Comparison of immunohistochemical localization of [Met5] enkephalin-Arg6-Gly7-Leu8, vasoactive intestinal polypeptide and tyrosine hydroxylase in the major pelvic ganglion of the rat

The major pelvic ganglion is an autonomic ganglion containing both sympathetic and parasympathetic postganglionic neuronal cell bodies. The existence of the proenkephalin A-derived peptide [Met5]enkephalin-Arg6-Gly7-Leu8 immunoreactivity in the rat major pelvic ganglion has been described quite recently. The aim of this study was to compare the relations of [Met5]enkephalin-Arg6-Gly7-Leu8-containing postganglionic neurons and nerve fibers to noradrenergic (tyrosine hydroxylase-immunoreactive) and non-noradrenergic (putative cholinergic) neurons of the rat major pelvic ganglion. Immunohistochemical double staining and elution-restaining techniques were used to investigate the distribution of [Met5]enkephalin-Arg6-Gly7-Leu8 in correlation with tyrosine hydroxylase and vasoactive intestinal polypeptide. The major pelvic ganglion contained neurons immunoreactive either for tyrosine hydroxylase or vasoactive intestinal polypeptide. Many principal neurons, however, were immunoreactive for tyrosine hydroxylase nor vasoactive intestinal polypeptide. [Met5]Enkephalin-Arg6-Gly7-Leu8-immunoreactive principal neurons formed a minor subpopulation in the ganglion and were not immunoreactive for tyrosine hydroxylase. The majority of [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive principal cells were non-immunoreactive for vasoactive intestinal polypeptide, but a few of them also contained vasoactive intestinal polypeptide. In contrast to the large [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive principal neurons, which formed a population of non-noradrenergic (putative cholinergic) cells, the small [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive cell exhibited intense tyrosine hydroxylase immunofluorescence and represented a subpopulation of small, intensely fluorescent cells. [Met5]Enkephalin-Arg6-Gly7-Leu8-immunoreactive pericellular fiber plexuses were found around tyrosine hydroxylase- and vasoactive intestinal polypeptide-immunoreactive principal neurons and in association with small intensity fluorescent cells.(ABSTRACT TRUNCATED AT 250 WORDS)

PACAP, a VIP-like peptide: immunohistochemical localization and effect upon cat pial arteries and cerebral blood flow

Pituitary adenylate cyclase activating peptide (PACAP) is a vasoactive intestinal polypeptide (VIP)-like peptide recently isolated from ovine hypothalami. Nerve fibers containing PACAP immunoreactivity were present in the adventitia and the adventitia-media border of cat cerebral arteries. Double immunostaining revealed that PACAP-immunoreactive nerve fibers constituted a subpopulation of the VIP-containing fibers. PACAP effected a concentration-dependent relaxation of feline middle cerebral arteries that had been precontracted with prostaglandin F2 alpha. The maximum relaxation, 24 and 34% of precontraction, was achieved with PACAP-38 and PACAP-27, respectively, at a concentration of 10(-6) M. In cats anesthetized with alpha-chloralose, intracerebral microinjection of PACAP effected a moderate increase in cerebral blood flow. The maximal increase (18.6 +/- 6%) was observed following the injection of 5 micrograms PACAP.

Mesenteric neurons in the adult rat are responsive to ileal treatment with benzalkonium chloride

The application of a 2 mM solution of the cationic surfactant benzalkonium chloride (BAC) to an ileal segment produced a selective and extensive myenteric denervation. The aim of the present study was to investigate whether such a selective unbalance of the enteric nervous system in the adult rat elicited any plastic response within the mesenteric nervous structures contacting it. Acetylcholinesterase (AChE) staining, beta-nicotinamide adenine dinucleotide (NADH) and beta-nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry and glyoxylic acid-induced fluorescence were performed on whole-mount preparations of myenteric plexus and mesenteric nerves. In both control and BAC-treated animals nervous elements were detected along the mesenteric nerves. Although rather similar in position, shape and size, these neurons displayed striking differences with regard to their arrangement and density per nerve. In the controls, few small aggregates of neurons could be detected; more commonly, isolated nerve cell bodies were scattered along the nerve trunks. In the BAC-treated animals, numerous spherical or spindle-shaped clusters of neurons were located along the nerves; the mean neuronal density per nerve displayed a two-five-fold increase over the control values. The observed changes within the mesenteric nerves might be involved in an attempt at reinnervation of the BAC-treated intestinal segments from extra-enteric sources.

Cell interactions that determine sympathetic neuron transmitter phenotype and the neurokines that mediate them

The transmitter properties of both developing and mature sympathetic neurons are plastic and can be modulated by a number of environmental cues. Cell culture studies demonstrate that noradrenergic neurons can be induced to become cholinergic and that the expression of neuropeptides can be altered. Similar changes in transmitter phenotype occur in vivo. During development, noradrenergic neurons that innervate eccrine sweat glands acquire cholinergic and peptidergic function. This change is dependent upon interactions with the target tissue. Following injury of sympathetic neurons in developing and adult animals, striking alterations take place in peptide expression. Ciliary neurotrophic factor and cholinergic differentiation factor/leukemia inhibitory factor, members of a family that includes several hematopoietic cytokines, induce cholinergic function and modulate neuropeptide expression in cultured sympathetic neurons. Studies in progress provide evidence that members of this new cytokine family influence the transmitter phenotype of sympathetic neurons not only in vitro but also in vivo.

Detection of subclinical autonomic neuropathy in constipated patients using a sweat test

Chronic idiopathic constipation may be the result of an autonomic neuropathy. This hypothesis was tested in 23 constipated patients and 17 age matched controls, using the acetylcholine sweat spot test devised to test autonomic integrity in diabetes. Acetylcholine (0.01%) was injected in the dorsum of the foot painted with a mixture of starch and iodine. Active sweat glands appeared on the surface of the skin as small black dots which were photographed and counted, using a grid with 60 subareas. Two measurements were made: the number of dots per unit subarea (sweat spot test score) and the % number of abnormal subareas (with less than six spots). These two parameters were correlated. The median sweat spot test score was 9.53 in patients and 13.92 in controls (p = 0.0001), the receiver operating characteristic curve showing that a score of 12 delimited normal and abnormal subjects. Increasing age was correlated with a low score in patients, probably because of prolonged symptoms. Seventy per cent of patients and one control had a borderline or abnormal number of subareas. These results suggest that idiopathic constipation is associated with a degree of autonomic denervation. The sweat spot test is an easy, inexpensive method to test this hypothesis and deserves a place in the clinical assessment of slow transit constipated patients.

Distributions of neuropeptide Y, vasoactive intestinal peptide and somatostatin in populations of postganglionic neurons innervating the rat kidney, spleen and intestine

Some peripheral peptidergic nerves selectively innervate different types of tissue in abdominal organs. Neuropeptide Y- and vasoactive intestinal peptide-immunoreactive nerve terminals have been identified in the kidney, spleen and intestine and these peptides may have important physiological actions. Somatostatin has been found in sympathetic ganglia, and nerve terminals containing this peptide have been identified in the intestine. We have used fluorescent retrograde tracers to identify renal, splenic and mesenteric postganglionic neurons in rat sympathetic ganglia and then used immunocytochemistry to determine the proportions of these three identified groups of neurons displaying immunoreactivity for neuropeptide Y, vasoactive intestinal peptide and somatostatin. Most renal, splenic and mesenteric neurons were immunoreactive for neuropeptide Y and less than 1% of cells innervating these organs were immunoreactive for vasoactive intestinal peptide. Somatostatin immunoreactivity was present only in a small percentage of mesenteric neurons and not in renal or splenic neurons. The present study demonstrates that (i) the rat kidney, spleen and intestine do not differ in the proportion of innervation by neuropeptide Y-immunoreactive neurons, (ii) the solar plexus, splanchnic ganglion and chain ganglia (T12 and T13) provide very little vasoactive intestinal peptide-immunoreactive inputs to these organs, and (iii) somatostatin-immunoreactive neurons innervate the intestine but not the kidney or spleen.

Influence of spinal cord transection on the presence and axonal transport of CGRP-, chromogranin A-, VIP-, synapsin I-, and synaptophysin-like immunoreactivities in rat motor nerve

Using immunofluorescence and cytofluorimetric scanning (CFS), we investigated the short-term (1-7 days) influence of lower thoracic spinal cord transection on lumbar motor neurons. The content of calcitonin gene-related peptide- (CGRP) like immunoreactivity (LI), chromogranin A (Chr A)-LI, vasoactive intestinal polypeptide (VIP)-LI, Syn I-LI, and synaptophysin (p38)-LI in motor perikarya, and the anterograde and retrograde axonal transport of these substances in the sciatic nerve, were studied in nerve crush (6 h) experiments. During the week after transection, CGRP-LI in perikarya decreased, whereas Chr A-LI increased. VIP-LI, co-localized with Chr A-LI in motor perikarya, did not change after transection. The antero- and retrograde transport of CGRP-LI in the sciatic nerve, occurring in both motor and sensory axons, appeared unchanged in cytofluorimetric scanning (CFS) graphs, but the microscopical picture clearly showed that large motor axons had a decreased content of CGRP-LI at 3 and 7 days posttransection, whereas thinner axons were unchanged in fluorescence intensity. The anterograde transport of Chr A-LI, present in both motor and postganglionic adrenergic axons, was decreased 1 and 3 days after lesion, but returned to control by day 7. There was a marked decrease in anterograde transport of VIP-LI, present mainly in postganglionic sympathetic axons, at day 3, but at 7 days transport was normal. The amounts of transported p38, the synaptic vesicle marker, were in the normal range during the whole period. Syn I-LI accumulation anterogradely was somewhat decreased at 3 and 7 days posttransection, and at 1 day the retrograde accumulation was significantly increased. The results suggest that removal of supraspinal input to intact lower motor neurons causes alterations in metabolism and axonal transport of organelle-associated substances, partly probably related to the complex pattern of transmitter leakage from degenerating, descending nerve terminals. These alterations appear to take place also in postganglionic sympathetic neurons in the sciatic nerve, that originate in the lumbar sympathetic chain.

Immunohistochemical localization of calcitonin gene-related peptide and cotransmitters in a subpopulation of post-ganglionic neurons in the porcine inferior mesenteric ganglion

Applying double-fluorescence immunohistochemistry, adrenergic and non-adrenergic postganglionic sympathetic neurons, in the porcine inferior mesenteric ganglion (IMG) are subdivided according to size and cotransmitter content. Calcitonin gene related peptide (CGRP)-immunoreactive (IR) neurons are demonstrated to belong to the non-adrenergic, i.e. tyrosine hydroxylase- and DOPAmine-beta-hydroxylase-(D beta H)-negative subpopulation of postganglionic perikarya. Virtually all of the CGRP-IR postganglionic neurons exhibit colocalization with somatostatin (SOM), and, some of them with neuropeptide tyrosine (NPY). Additionally, NPY-, SOM-, and NPY/SOM-IR subpopulations of adrenergic and non-adrenergic neurons are observed. CGRP-immunoreactivity is seen in dense networks of intraganglionic varicose nerve fibres, adjacent to the TH- and SOM-IR neurons. NPY-IR perikarya are sparsely supplied by CGRP-IR fibres. SOM- and NPY-IR nerve fibres also exist in the inferior mesenteric ganglion. The functional relevance of CGRP-IR postganglionic neurons, as well as target organs of these neurons remain to be elucidated.

Comparison of locations and peptide content of postganglionic neurons innervating veins and arteries of the rat hindlimb

The ganglionic location of hindlimb vasoconstrictor sympathetic neurons in several species is known but the locations of neurons innervating limb arteries or veins, specifically, have not been compared and neurochemical differences between them have not been examined in detail. This study was designed to determine whether neurons innervating arteries and veins are organized as distinct populations and whether neurons innervating arteries, veins or footpads contain the same peptides. Retrograde transport of fluorescent dyes was used to identify, separately, paravertebral postganglionic neurons in the 13th thoracic to 6th lumbar (T13-L6) chain ganglia that innervate the femoral arteries, femoral veins and footpads of the rat hindlimb. The proportions of venous and arterial vasomotor neurons and footpad neurons containing neuropeptide Y- and vasoactive intestinal polypeptide-immunoreactivity (NPY-Ir, VIP-Ir) were then compared. Venous vasomotor neurons were found mostly (62%) in the L1 and L2 ganglia. The majority of arterial vasomotor neurons (81%) were distributed slightly more caudally in L1-L3. Veins and arteries were not innervated by the same cells. Footpad neurons were located mostly in L4-L6. NPY-Ir was identified in 17% of the venomotor neurons, in 94% of arterial neurons and in 24% of footpad neurons. VIP-Ir was found in 3% of the venomotor neurons, 8% of the arterial neurons and in 44% of the footpad neurons. In conclusion, hindlimb venous and arterial vasomotor neurons are anatomically distinct, are mixed randomly within the chain ganglia and differ markedly in their content of NPY, consistent with reported differences in neuromuscular transmission to arteries and veins. The most likely hindlimb postganglionic neurons to contain VIP were those innervating footpads, probably controlling sweat gland function.

Morphological basis for back pain: the demonstration of nerve fibers and neuropeptides in the lumbar facet joint capsule but not in ligamentum flavum

The innervation of lumbar facet capsule and ligamentum flavum was investigated using antisera to a general neuronal marker protein gene product (PGP) 9.5 and to peptide markers of sensory nerves (calcitonin gene-related peptide [CGRP] and substance P) and autonomic nerves (vasoactive intestinal polypeptide [VIP] and C-flanking peptide of neuropeptide Y [CPON]). In the facet capsule (n = 14), PGP 9.5 and CGRP-immunoreactive nerves occurred in 12 and five specimens, respectively, both around blood vessels and as free fibers in the stroma. Free fibers immunoreactive for substance P or VIP were noted in three and five specimens, whereas in nine specimens there were CPON-immunoreactive nerves located perivascularly. There was no immunoreactivity in the ligamentum flavum. This study provides further evidence that the facet capsule but not the ligamentum flavum has substantial innervation by sensory and autonomic nerve fibers and has a structural basis for pain perception.

Peptide-containing innervation of rat femoral lymphatic vessels

The lymphatic vessels conduct lymph fluid, proteins, and potentially antigenic material from the interstitium back to the bloodstream via lymph nodes, where solids are removed by phagocytic cells and recirculating lymphocytes and immunoglobulins are added. Immunostaining for two general neuronal markers, protein gene product 9.5 (PGP 9.5), a cytoplasmic ubiquitin C-terminal hydrolase, and synaptophysin, a calcium-binding four-span integral synaptic vesicle membrane glycoprotein, disclosed an abundant innervation of the large femoral lymphatic vessels in rats. This confirms and extends earlier findings based on nonspecific intravital methylene blue and silver impregnation staining methods. Nerves containing neuropeptide Y, C-flanking peptide of neuropeptide Y, and tyrosine hydroxylase, markers of noradrenergic postganglionic sympathetic fibers, were frequent whereas immunoreactivity to vasoactive intestinal peptide, a neuropeptide present in many cholinergic parasympathetic nerve fibers, was sparse suggesting possible sympathetic and parasympathetic influences. Furthermore, calcitonin gene-related peptide- and substance P-containing fibers were also present in the walls of lymphatic vessels suggesting a possible sensory influence in the coordinated myogenic responses. By comparison to normal light microscopy, confocal microscopy was found useful to trace the perihilar penetration of blood and afferent lymphatic vessels in lymph nodes. PGP 9.5-immunoreactive fibers were found in and around lymph nodes suggesting that there is a neural regulation of lymphoid node function. Because of their distribution, peptide-containing nerves may participate in regulating the capacity of the lymphatic pumping activity, and may possibly exert paracrine effects on lymphocytes.

Neuroendocrine peptides in bone

A method for demineralization of bone, preserving the antigenicity of neuroactive peptides, was developed. In all parts of rat long bones, nerves immunoreactive to substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) and tyrosine hydroxylase (TH) were detected after immunohistochemical staining. The majority of nerves were vascular, although several non-vascular endings were observed at the growth plate and amidst marrow cells. An abundance of nerves were demonstrated near the epiphyseal plate and in the periosteum, regions of high osteogenic activity. The occurrence of different nerve types was analyzed at different stages of heterotopic osteogenesis, induced by allogeneic bone matrix. Nerve fibres immunoreactive to SP, CGRP, NPY and TH occurred amidst differentiating chondroblastic cells in the second week. They gradually increased in number during the ensuing eight weeks. In an in vitro study of osteoblastic cells (UMR 106-01, ROS 17/2.8, Saos-2, MC3T3-E1) receptors to CGRP, VIP, noradrenaline (NA) and NPY were demonstrated as assessed by analysis of cyclic AMP formation. In UMR cells, NPY inhibited the effects of NA and parathyroid hormone (PTH), which is the first demonstration of a receptor interaction between a local neuropeptide and a systemic calcium regulating hormone. The combined findings indicate a neuroendocrine influence on bone physiology.

Pituitary adenylate cyclase activating peptide (PACAP) in guinea-pig lung: distribution and dilatory effects

The lower airways of guinea-pigs were analyzed for pituitary adenylate cyclase activating peptide (PACAP) using immunocytochemistry. In the trachea a moderate supply of PACAP-immunoreactive nerve fibers occurred around smooth muscle bundles, glands and small blood vessels. In the lung, PACAP-immunoreactive nerve fibers were distributed around small glands and bronchi. A rich supply of PACAP immunoreactive nerve fibers was found around blood vessels in the lungs. PACAP-suppressed smooth muscle responses were analysed using isolated circular segments of trachea, pulmonary arteries and aorta of guinea-pigs. In both airways and arteries PACAP caused a concentration-dependent relaxation of precontracted segments. The maximal relaxation effects were more pronounced in the airways than in the arteries while the order of potency was aorta greater than pulmonary artery greater than trachea. The effect of PACAP was compared to those of acetylcholine (ACh) and vasoactive intestinal peptide (VIP). In the pulmonary artery the vasomotor responses expressed as maximal dilatation had the order: ACh greater than VIP = PACAP while the order of potency was PACAP = VIP greater than ACh. In the trachea, PACAP was slightly more potent than VIP. The relaxatory responses to PACAP in the trachea and the intrapulmonary arteries were unaffected by pretreatment with atropine, prazosin, yohimbine, propranolol, mepyramine, cimetidine and Spantide. Removal of the endothelium abolished PACAP-induced vascular relaxation. Conceivably, PACAP-containing nerve fibers play a role in the regulation of airway resistance and local blood flow.

Enkephalinergic sympathetic and parasympathetic innervation of the rat submandibular and sublingual glands

Enkephalinergic innervation of the rat salivary glands was investigated by immunocytochemical techniques. Based upon immunostaining for enkephalin (ENK) and tyrosine hydroxylase (TH), 4 types of neurons could be distinguished in the submandibular ganglion: cells containing both ENK and TH (9% of all ganglion cells), cells containing only ENK (17%), cells containing only TH (4%) and cells lacking both ENK and TH (70%). Almost all of the ganglion neurons were also positive for AChE and so were most of the TH-positive cells. The ENK-positive fibers outnumbered the TH-positive fibers. Although TH-positive fibers displayed concurrent ENK immunoreactivity, fibers in the blood vessel walls were only immunoreactive for TH. Excision of the superior cervical ganglion resulted in a decrease of ENK fibers and the disappearance of most of the TH fibers from the submandibular gland. Most of the remaining ENK-positive fibers were immunonegative for TH, while the remaining TH-positive fibers were also positive for ENK. The salivary gland of the postnatal 8-week-old rats had a considerable number of ENK-positive neurons and fibers in the submandibular ganglion and acini.

An immunocytochemical study of cutaneous innervation and the distribution of neuropeptides and protein gene product 9.5 in man and commonly employed laboratory animals

The cutaneous nerves of rat, cat, guinea pig, pig, and man were studied by immunocytochemistry to compare the staining potency of general neural markers and to investigate the density of nerves containing peptides. Antiserum to protein gene product 9.5 (PGP 9.5) stained more nerves than antisera to neurofilaments, neuron-specific enolase (NSE), and synaptophysin or histochemistry for acetylcholinesterase (AChE). Peptidergic axons showed species variation in density of distribution and were most abundant in pig and fewest in man. However, the specific peptides in nerves innervating the various structures were consistent between species. Nerve fibers immunoreactive for calcitonin gene-related peptide (CGRP) and/or vasoactive intestinal polypeptide (VIP) predominated in all the species; those immunoreactive to tachykinins (substance P and neurokinin A [NKA]) and neuropeptide tyrosine (NPY) were less abundant. Neonatal capsaicin, at the doses employed in this study, destroyed approximately 70% of CGRP- and tachykinin-immunoreactive sensory axons; whereas 6-hydroxydopamine (6-OHDA) at the doses employed resulted in a complete loss of NPY and tyrosine hydroxylase (TH) immunoreactivity without affecting VIP, CGRP, and tachykinins. Thus, this study confirms that antiserum to PGP 9.5 is the most suitable and practical marker for the demonstration of cutaneous nerves. Species differences exist in the density of peptidergic innervation, but apparently not for specific peptides. Not all sensory axons immunoreactive for CGRP and substance P/NKA are capsaicin-sensitive. However, all sympathetic TH- and NPY-immunoreactive axons are totally responsive to 6-OHDA; but no change was seen in VIP-immunoreactive axons, suggesting some demarcation of cutaneous adrenergic and cholinergic sympathetic fibers.

Concentrations of neuropeptides substance P, neurokinin A, calcitonin gene-related peptide, neuropeptide Y and vasoactive intestinal polypeptide in synovial fluid of the human temporomandibular joint. A correlation with symptoms, signs and arthroscopic findings

Arthroscopy was performed on 18 patients (19 joints) with temporomandibular joint arthropathy. Arthroscopic investigation revealed that 12 patients had disk derangement, including 3 patients with rheumatoid arthritis. Six patients had osteoarthrosis, including one patient with rheumatoid arthritis. Synovial fluid content of substance P-like immunoreactivity (SP-LI), neurokinin A (NKA-LI), calcitonin gene-related peptide (CGRP-LI), neuropeptide Y (NPY-LI) and vasoactive intestinal polypeptide (VIP-LI) were analysed using radioimmunoassay technique. All peptides analysed were found, although in various concentrations, in the different joints. There were no significant differences in concentrations of the peptides in the synovial fluid between patients in the various groups. No significant correlation was found between clinical symptoms and signs, arthroscopic findings, or use of analgesic/anti-inflammatory medication versus concentrations of peptides in the synovial fluid. In comparison with earlier findings in the knee joint significantly higher concentrations of SP-LI, CGRP-LI and NPY-LI were found in the TMJ.

A quantitative study of neuropeptide immunoreactive cell bodies of primary afferent sensory neurons following rat sciatic nerve peripheral axotomy

Following peripheral axotomy, fluoride resistant acid phosphatase (FRAP) and most neuropeptides are depleted in the central terminals of axotomised nerves and reduced in their corresponding cell bodies (DRG) but vasoactive intestinal polypeptide (VIP) increases. The increase in VIP probably results from a change in gene expression in other ganglion cells which do not normally express VIP. A quantitative study was performed to investigate the proportion of DRG cells immunoreactive for different peptides at increasing times after sciatic nerve section. Retrograde fluorescent neuronal labelling of sciatic nerve cell bodies by injection of fast blue into the proximal stump was combined with unlabelled antibody immunohistochemistry for CGRP and VIP. The proportion of cells immunoreactive for these peptides was quantified between two and fourteen days post-axotomy. The number of VIP immunoreactive profiles increased significantly in the first 4 days post-axotomy, followed by a slight decrease before rising again. In contrast, the number of and CGRP-immunoreactive cell profiles declined to zero by 14 days post-axotomy. 4 days post-axotomy 50% of VIP positive cells were also immunoreactive for CGRP. There was neither colocalisation between VIP and FRAP nor between CGRP and FRAP. It is concluded that many peptidergic DRG cell bodies switch their expression of peptide to VIP after injury, whereas non-peptide-containing subpopulations do not.

Peptidergic and serotoninergic innervation of the rat dura mater

The peptidergic and serotoninergic innervation of the rat dura mater was investigated by reacting dural wholemounts immunohistochemically with antibodies to calcitonin gene-related peptide (CGRP), substance P (SP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), and serotonin (5-HT). CGRP and SP innervations of the dura were robust and the patterns of distribution of these neuropeptides were essentially the same. The majority of the fibers were perivascular and distributed to branches of the anterior and middle meningeal arteries and to the superior sagittal and transverse sinuses. Other CGRP/SP fibers appeared to end "free" within the dural connective tissue. NPY-immunoreactive fibers were extremely numerous and also distributed heavily to the branches of the meningeal arteries, the venous sinuses, and to the dural connective tissue. The pattern of NPY innervation resembled in many ways that of CGRP/SP; however, NPY innervation of the sinuses was greater and NPY perivascular fibers supplying the meningeal arteries formed more intimate contacts with the walls of the vessels. The pattern of VIP innervation was, in general, similar to that observed for the three previous neuropeptides; however, the overall density was considerably less. Small to moderate numbers of serotoninergic nerve fibers were observed in some, but not all, of the duras processed for 5-HT. The latter fibers were almost exclusively perivascular in distribution. Dural mast cells were prominently stained in the 5-HT preparations because of their serotonin content. Mast cells were also labeled in a nonspecific fashion in some of the tissues reacted immunohistochemically for neuropeptides; some of them were located in close apposition to passing nerve fibers. This study represents, to our knowledge, the first comprehensive work on the peptidergic and serotoninergic innervation of the mammalian dura mater. The results should increase our understanding of the roles that these fibers play in normal dural physiology and of their potential interactions in the pathogenesis of vascular headache.

Vasoactive intestinal peptide fluctuates in human blood with a circadian rhythm

The vasoactive intestinal peptide (VIP) may be radioimmunoassayed in systemic venous blood. The plasma concentrations of VIP were investigated in human blood according to a chronobiological design. The study documented a circadian rhythmicity in time-qualified concentrations of VIP. Accordingly, VIP may be ascribed to biological variables characterized by periodicity in their physiological attributes. The rhythmic physiology of VIP is, however, highly disturbed in its tonic and phasic properties during senescence.

Pituitary adenylate cyclase-activating peptide (PACAP), a new vasoactive intestinal peptide (VIP)-like peptide in the respiratory tract

Pituitary adenylate cyclase-activating peptide (PACAP) is a vasoactive intestinal peptide (VIP)-like peptide recently isolated from ovine hypothalami. Nerve fibers displaying PACAP immunoreactivity were found in the respiratory tract of rats, guinea pigs, ferrets, pigs, sheep and squirrel monkeys. A moderate supply of PACAP-immunoreactive fibers was seen in the nasal mucosa of guinea pigs. Few to moderate numbers of PACAP-containing fibers occurred in the tracheo-bronchial wall of rats, guinea pigs, ferrets, pigs, sheep and squirrel monkeys. The fibers were distributed beneath the epithelium, around blood vessels and seromucous glands, and among bundles of smooth muscle. In the lungs, the immunoreactive fibers were observed close to small bronchioli. A few PACAP-immunoreactive nerve cell bodies were seen in the sphenopalatine and otic ganglia of guinea pigs. Simultaneous double immunostaining of the respiratory tract of sheep and ferrets revealed that all PACAP-containing nerve fibers stored VIP. We suggest that neuronal PACAP may take part in the regulation of smooth muscle tone and glandular secretion.

Localization of substance P, CGRP, VIP, neuropeptide Y, and somatostatin immunoreactive nerve fibers in the carotid labyrinths of some amphibian species

Immunohistochemical localization of substance P (SP), CGRP, VIP, neuropeptide Y (NPY), and somatostatin (SOM) in the carotid labyrinth were compared in some species of amphibians using the peroxidase-antiperoxidase method. Immunoreactivity of SP, CGRP, VIP, and NPY was found in the nerve fibers distributed in the intervascular stroma of the carotid labyrinth. SP, CGRP, and VIP immunoreactive varicose fibers were densely distributed in the peripheral portion of the carotid labyrinth. Some SP-immunoreactive fibers were distributed similarly to CGRP-immunoreactive fibers. The density of NPY and SOM immunoreactive varicose fibers was low. No immunoreactivity of enkephalins was observed in the labyrinth. The intensities of these peptides were varied from species to species. No glomus cells showed immunoreactivity for any of the 7 peptides studied. These results suggest that the vascular regulatory function, which is one of the possible functions of the carotid labyrinth, is controlled by the peptidergic mechanisms in addition to regulation through intimate apposition of glomus and smooth muscle cells (g-s connection).

Modulation of neuropeptide expression in avian embryonic sympathetic cultures

Two distinct neuropeptide-related phenotypes are found in avian paravertebral sympathetic ganglia, corresponding to somatostatin- (SS) and vasoactive intestinal polypeptide- (VIP) expressing cells. We have detected the same cell phenotypes in cultures of embryonic quail sympathetic ganglia and have used this system to study the modulation of their expression by the environment. The cell phenotypes were identified using immunocytochemistry and induced catecholamine fluorescence and quantitative data were obtained by radioimmunoassay. Dissociation of the ganglia caused a profound increase in the expression of VIP but had no effect on SS levels. Addition of corticosterone (10(-6) M) increased the expression of SS without modifying VIP levels. In contrast, depolarization of the cells induced changes in levels of both neuropeptides. The modulation of VIP correlates with the modulation of cholinergic properties. The regulation of neuropeptide expression in the avian system shows both similarities and differences to what has been found in the mammalian system.

Acetylcholine levels and choline acetyltransferase activity in rat cerebrovascular bed after uni- or bilateral sphenopalatine ganglionectomy

Endogenous acetylcholine (ACh) levels and choline acetyltransferase (ChAT) activity were measured in several vascular segments (major cerebral arteries, cortical pial vessels, and peripheral arteries) and nervous tissues [including the sphenopalatine ganglion (SPG)] in the rat. The effects of uni- or bilateral surgical ablation of the SPG, a putative origin of the cholinergic cerebrovascular innervation, were investigated on these two specific cholinergic markers at various postoperative times. ChAT activity and ACh levels were enriched in the cerebral as compared to the peripheral arteries. Among the cerebrovascular tissues tested, ACh levels were particularly high in the circle of Willis and the vertebrobasilar segments and, to a lesser extent, in the middle cerebral artery. Lower levels were found in the small pial vessels and choroid plexus. Overall, ChAT activity measured in different arterial beds paralleled the distribution of ACh. Following uni- or bilateral removal of the SPG, slight reductions (18-36%, statistically not significant) were observed in ChAT activity in rostral cerebral arteries and pial vessels overlying the frontal cortex. Similarly, bilateral ganglionectomy resulted in minor decreases (11-22%, not significant) in the cerebrovascular contents of ACh in these same vascular segments. These results clearly show that the SPG does not or only partly contributes to the cholinergic fibers that supply the cerebrovascular bed.

Parasympathetic innervation of cutaneous blood vessels examined by retrograde tracing in the rat lower lip

The origin of vasoactive intestinal polypeptide (VIP)-immunoreactive and acetylcholinesterase (AChE)-positive perivascular nerve fibers in the lower lip of rats was investigated using the retrograde tracer, wheat germ agglutinin conjugated to enzymatically inactive horseradish peroxidase gold complex (WGAapoHRP-Au), in combination with immunohistochemistry and enzyme histochemistry, by comparing the cells of origin of projection to the parotid gland. After the application of the tracer to the lip, small- to medium-sized nerve cells were labelled exclusively in the ipsilateral otic ganglion. Most of them showed moderate VIP-immunoreactivity and AChE activity. In contrast, injection into the parotid gland resulted in labelling of mostly large-sized cells of the otic ganglion which showed intense VIP-immunoreactivity and AChE activity. These results confirmed that the parasympathetic innervation of the rat lip originates from the otic ganglion. It was further suggested that there are at least two subpopulations in the otic ganglion cells, different from each other in size and in VIP-immunoreactivity, which separately innervate the salivary gland and the blood vessels.

Concentration of substance P, neurokinin A, calcitonin gene-related peptide, neuropeptide Y and vasoactive intestinal polypeptide in synovial fluid from knee joints in patients suffering from rheumatoid arthritis

We have studied the presence of five neuropeptides in knee joint synovial fluid from either patients suffering from rheumatoid arthritis and pain (n = 18) or being subjected to arthroscopy due to meniscal/cruciate ligament injuries (n = 13). Radioimmunoassay technique was used for peptide analysis using antisera SP2 against substance P (SP), K12 against neurokinin A (NKA), CGRPR8 against calcitonin gene-related peptide (CGRP), NPY1 against neuropeptide Y (NPY) and VIP2 against vasoactive intestinal polypeptide (VIP). No SP could be detected, and lower levels of NKA was found in arthritic joints vs controls. CGRP and NPY was found in higher concentrations in arthritic patients vs controls. VIP was found sporadically in both arthritis and control patients. Our data show some quantitative differences between patients suffering rheumatoid arthritis and pain, and patients with non-inflamed joints without pain; indicating an involvement of peptidergic fibers in arthritis in humans.

Neuropeptide Y- and vasoactive intestinal polypeptide-containing nerve fibers in the human cerebral arteries: characteristics of distribution

Perivascular innervation in cerebral arteries from 28 human fetuses at twelve to twenty-eight weeks' gestational age was studied histochemically. Neuropeptide Y (NPY)- and vasoactive intestinal polypeptide (VIP)- containing nerve fibers were densely distributed along with adrenergic and cholinergic nerve fibers in the major pial arteries at the base of the brain, an area that forms the circle of Willis, and in the lenticulostriate arteries. In contrast, distribution was sparse in the cortical circumflex branches of the middle cerebral artery, as compared with findings in the lenticulostriate artery of the same diameter. Densely distributed perivascular nerve fibers in the lenticulostriate arteries may play an important role in the pathogenesis of intracerebral hemorrhage.

Assessment of basal and stimulated sweating in diabetes using a direct-reading computerized sudorometer

Abnormalities of eccrine sweating are thought to be common in diabetes. We describe a ventilated-capsule sudorometer for the continuous measurement of basal and stimulated sweat secretion. It is sensitive (detecting as little as 200 ng water vapour), precise, and stable. Since it measures dewpoint rather than relative humidity, it can be calibrated to read sweat volumes directly and independently of ambient temperature and humidity. Preliminary studies using this technique show that basal skin water loss is significantly diminished in patients with established diabetic neuropathy (0.91 +/- 0.18 g (+/- SD) cm-2 h-1) compared with normal subjects (1.21 +/- 0.39 g cm-2 h-1; p = 0.04) and non-neuropathic diabetic subjects (1.32 +/- 0.48 g cm-2 h-1; p = 0.04), and that local sweating induced by iontophoresis of 10 g l-1 acetylcholine is significantly reduced in diabetic subjects up to 5 min of recording (0.95 +/- 0.43 vs 1.26 +/- 0.40 mg; p = 0.02). In neuropathic subjects both low- and high-amplitude responses are seen, the latter probably representing denervation supersensitivity. Further studies with sensitive sudorometry should enable the mechanisms of these abnormal responses to be established.

Immunohistochemical localization of [Met5]enkephalin and [Met5]enkephalin-Arg6-Gly7-Leu8 in sympathetic and parasympathetic neurons and nerve fibers projecting to the rat submandibular gland

The localization of [Met5]enkephalin, [Met5]enkephalin-Arg6-Gly7-Leu8, vasoactive intestinal polypeptide and tyrosine hydroxylase immunoreactivities was studied in the submandibular gland of adult Sprague-Dawley and Wistar rats using the indirect immunofluorescence technique. Immunoreactivities for [Met5]enkephalin and [Met5]enkephalin-Arg6-Gly7-Leu8, a proenkephalin A-derived octapeptide, showed identical distributions. A large number of enkephalin-immunoreactive nerve fibers were detected around secretory acini, along intercalated ducts, convoluted granular tubules, intra- and interlobular ducts, as well as in close contact with blood vessels. The submandibular ganglia contained several enkephalin-immunoreactive neurons and nerve fibers. In the superior cervical ganglion numerous enkephalin-immunoreactive neurons and nerve fibers were also detected. Immunohistochemical co-localization studies indicated that [Met5]enkephalin and [Met5]enkephalin-Arg6-Gly7-Leu8 immunoreactivities co-exist with vasoactive intestinal polypeptide in a subpopulation of neurons of the rat submandibular ganglia, in nerve trunks along the salivary ducts of the gland, and in nerve fibers around the acini. Uni- or bilateral superior cervical ganglionectomies for 1-4 weeks resulted in a complete disappearance of tyrosine hydroxylase immunoreactivity in the glandular parenchyma, while moderate tyrosine hydroxylase immunoreactivity was seen in some neurons of the submandibular ganglia. Abundant [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive nerve fibers were still seen around the acini and blood vessels, as well as close to salivary ducts. These operations did not affect the [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive neurons in the submandibular ganglia. Many principal neurons in the superior cervical ganglion contained both [Met5]enkephalin-Arg6-Gly7-Leu8 and tyrosine hydroxylase immunoreactivity. Nerve ligation experiments indicated that [Met5]enkephalin-Arg6-Gly7-Leu8-immunoreactive sympathetic fibers project along the external carotid nerve. Accordingly, nerve fibers were found around the acini and blood vessels as well as in nerve trunks along the salivary ducts of the submandibular gland, showing co-localization of [Met5]enkephalin-Arg6-Gly7-Leu8 and tyrosine hydroxylase. Taken together, these observations suggest that the nerve fibers of the rat submandibular gland containing proenkephalin A-derived peptides are of both sympathetic and parasympathetic origin.

Characterization of a target-derived neuronal cholinergic differentiation factor

The sympathetic innervation of rat sweat glands undergoes a target-induced switch from a noradrenergic to a cholinergic and peptidergic phenotype during development. Treatment of cultured sympathetic neurons with sweat gland extracts mimics many of the changes seen in vivo. Extracts induce choline acetyltransferase activity and vasoactive intestinal peptide expression in the neurons in a dose-dependent fashion while reducing catecholaminergic properties and neuropeptide Y. The cholinergic differentiation activity appears in developing glands of postnatal day 5 rats and is maintained in adult glands. It is a heat-labile, trypsin-sensitive, acidic protein that does not bind to heparin-agarose. Immunoprecipitation experiments with an antiserum directed against an N-terminal peptide of a cholinergic differentiation factor (CDF/LIF) from heart cells suggest that the sweat gland differentiation factor is not CDF/LIF. The sweat gland activity is a likely candidate for mediating the target-directed change in sympathetic neurotransmitter function observed in vivo.

Acetylcholinesterase activity in antennal receptor neurons of the sphinx moth Manduca sexta

We have used a cytochemical technique to investigate the distribution of acetylcholinesterase (AChE) activity in the antenna of the sphinx moth Manduca sexta. High levels of echothiophate-insensitive (presumably intracellular) AChE activity were found in six different types of antennal receptors localized in specific regions of the three antennal segments of the adult moth. Mechanosensory organs in the scape and pedicel, the Böhm bristles and Johnston's organ, are innervated by AChE-positive neurons. In each annulus of the antennal flagellum, AChE-positive neurons are associated with six sensilla chaetica and a peg organ, probably a sensillum styloconicum. At least 112 receptor neurons (8-10 per annulus) innervating the intersegmental membranes between the 14 distalmost annuli also exhibit high levels of echothiophate-resistant AChE. In addition, each annulus has more than 30 AChE-positive somata in the epidermis of the scale-covered (back) side of the flagellum, and 4 AChE-positive somata reside within the first annulus of the flagellum. Since none of the olfactory receptor neurons show a high level of echothiophate-resistant AChE activity, and all known mechanoreceptors are AChE-positive, apparently "intracellular" AChE activity in the antenna correlates well with mechanosensory functions and is consistent with the idea that these cells employ acetylcholine as a neurotransmitter.

Immunohistochemical localization of 5-hydroxytryptamine, histamine and histidine decarboxylase in the rat major pelvic and coeliac-superior mesenteric ganglion

The localization of 5-hydroxytryptamine (5-HT), histamine and histidine decarboxylase (HDC), the enzyme synthesizing histamine, was studied in the rat major pelvic and coeliac-superior mesenteric ganglia by an indirect immunofluorescence technique. Small cells (10-20 microns in diameter) exhibiting 5-HT, histamine or HDC immunoreactivities were observed in clusters or occurred as solitary cells in both ganglia. In the major pelvic ganglia, solitary histamine-immunoreactive principal neurons were also observed. Colocalization studies indicated that all 5-HT-, histamine- and HDC-immunoreactive small cells in these ganglia were labelled with tyrosine hydroxylase (TH), suggesting that they are small intensely fluorescent (SIF) cells. In the coeliac-superior mesenteric ganglia, all TH-immunoreactive SIF cells were also intensely immunoreactive for 5-HT and HDC. In the major pelvic ganglia, all TH-immunoreactive SIF cells contained 5-HT immunoreactivity, and the majority of them were also intensely immunoreactive for HDC. In both ganglia, however, only a subpopulation of TH-immunoreactive SIF cells displayed histamine immunoreactivity. The results indicate that in the rat major pelvic and coeliac-superior mesenteric ganglia, a population of catecholamine-containing SIF cells contain 5-HT and histamine suggesting a diverse role SIF cells may have in so far as modulation of ganglion transmission is concerned.

Peptidergic innervation in the cerebral blood vessels of the guinea pig: an immunohistochemical study

The distribution of peptidergic nerve fibers containing substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY) in the cerebral arteries and veins of the guinea pig was studied using immunohistochemical techniques. The ultrastructure of these immunoreactive nerve terminals was also compared. The cerebral arteries were innervated by abundant peptidergic nerve fibers with characteristic running patterns, i.e., SP fibers in a meshwork, VIP and NPY fibers in a spiral fashion. Only CGRP fibers showed both meshwork and spiral patterns. In the cerebral veins, the abundant SP fibers innervated the cortical veins, deep cerebral veins, and dural sinuses. However, CGRP, VIP, and NPY fibers in extremely low density were noted merely in the cortical veins. Electron microscopic observations demonstrated that SP-immunoreactive nerve terminals existed apart from the arterial smooth muscle cells, while VIP- and NPY-immunoreactive nerve terminals adjoined them. As for CGRP nerve terminals, some existed close to the arterial smooth muscle cells, and others were found some distance from them. These morphological characteristics observed by light and electron microscopy suggest that SP fibers are not related directly to the vasomotor function, but VIP and NPY fibers are, and that CGRP fibers have a more complicated function. The distribution patterns of the peptidergic nerve fibers are consistent with the suggestion that vasomotor peptidergic fibers may function actively on cerebral arteries and passively on cerebral veins and that SP fibers regarded as sensory fibers may provide information regarding cerebral vascular conditions, innervating every part of both cerebral arteries and veins.

Studies of vasoactive intestinal polypeptide expression in injured peripheral neurons using capsaicin, sympathectomy and mf mutant rats

The increased expression of vasoactive intestinal polypeptide (VIP) in injured peripheral neurons was studied. In contrast to substance P, there was a marked increase, and maintained fast axonal transport, of VIP in rat sciatic nerve after peripheral axotomy. Local capsaicin application to the nerve trunk failed to inhibit the injury-induced VIP increase, and capsaicin even increased VIP levels when applied locally to uninjured nerves. Pharmacological sympathectomy showed that some of the peripheral VIP increase may occur in post-ganglionic sympathetic fibres. The VIP increase after injury appeared unaffected in the mf mutant rat, in spite of its loss of lumbar dorsal root ganglion cells. VIP-staining fibres in the epi- and peri-neurium and perivascular plexuses of sciatic nerve showed an increase in number in parallel with the changes of the nerve VIP content. These findings suggest that sensory and sympathetic nerve fibres expressing VIP after injury play a role in the regulation of blood flow to nerves, and in the pathophysiological processes in nerve and dorsal spinal cord which follow peripheral nerve injury.

Cardiac responses to VIP and VIP-ergic-cholinergic interaction in isolated dog heart preparations

Whereas i.v. administration of vasoactive intestinal peptide (VIP) to support dogs increased heart rate and decreased systemic blood pressure, sinus rate and contractile force increased in isolated right atria perfused with blood from the support dogs. VIP injected intraarterially into isolated atria induced dose-dependent positive chronotropic and inotropic effects. Intracardiac parasympathetic nerve stimulation attenuated the positive cardiac responses to VIP, but neither propranolol, imipramine, nor tetrodotoxin influenced the responses to VIP. VIP given to isolated left ventricles also increased the contractile force in a dose-dependent manner. However, VIP induced a greater maximum atrial contractility than ventricular contractility. This may indicate that VIP receptor density in the ventricle was lower than in the atrium, as it has recognized that VIP-ergic nerves innervate the right atrium more densely than the left ventricle. We therefore suggest that the positive cardiac responses to VIP, together with the VIP-ergic innervation in dog hearts and vagal activation, attenuate the VIP-mediated responses at site(s) in the cyclic AMP cascade.

Immunohistochemical studies on the development of cells containing progastricsin (minor pepsinogen) in comparison to prochymosin and pepsinogen in bovine abomasal mucosa

The localization of progastricsin was studied in cells of abomasal mucosa from cattle of different ages and feeding regimes and compared to the localization of prochymosin and pepsinogen in the same material by use of an immunofluorescence technique with specific rabbit antibodies. Immunoreactivity for progastricsin was first found in calves at the age of about 45 days in surface mucous cells in the pit of the fundic gland. In older calves and adults, mucous neck cells also produced progastricsin. In the pyloric mucosa, on the other hand, traces of progastricsin immunoreactivity were found in the lower base of the pyloric gland even in newborn calves. When the calves grew older, progastricsin-immunoreactive cells also developed in the pit and later in the neck of the pyloric gland; and the number of these cells in this region increased with age. The development of progastricsin-producing cells seemed to be influenced only by age and not by the feeding of milk to the calves. The ontogeny of progastricsin, prochymosin, and pepsinogen exhibited an interesting pattern in cattle, as they started to be produced at three different ages and gave three different patterns of development in the cells of abomasal mucosa. The number of cells producing prochymosin was closely correlated with milk-feeding, while the development of progastricsin was most related to the age of the calf. The most stable factor during the development of the cells in the abomasum was the number of cells producing pepsinogen.

Vasoactive intestinal peptide (VIP) and peptide histidine methionine (PHM) in human eccrine sweat glands: demonstration of innervation, specific binding sites and presence in secretions

Vasoactive intestinal peptide (VIP) and peptide histidine methionine (PHM) immunoreactivities have been detected in alcohol extracts of human axillary skin using sensitive and specific radioimmunoassays. VIP immunoreactivity (7.63 + 2.33 pmol/g, x + SE, n = 9) was more abundant than PHM immunoreactivity (3.86 + 0.56 pmol/g, x + SE, n = 9). Immunocytochemistry of sections of skin revealed a network of VIP/PHM immunoreactive nerve fibres around the perimeter of eccrine but not apocrine sweat glands. In vitro autoradiography of skin sections using 125I-labelled VIP and PHM, demonstrated binding sites on the membranes of eccrine gland secretory cells. The binding of each radiolabelled ligand was eliminated by the presence of a large molar excess of appropriate cold peptide but was unaffected when incubated with related peptide, indicating the presence of specific binding sites for both VIP and PHM. Radioimmunoassay of Sep-pak concentrated human sweat identified the presence of both VIP immunoreactivity (30.6 pmol/l) and PHM immunoreactivity (43.4 pmol/l). Reverse-phase HPLC analysis of axillary skin extracts and sweat, followed by radioimmunoassay of fractions, identified single resolved peaks of VIP and PHM immunoreactivity with identical retention times to synthetic standards. Eccrine sweat glands in human axillary skin have VIP and PHM peptidergic innervation and possess specific binding sites for each peptide which are both secreted to the surface of the skin.

Differentiation of embryonic chick sympathetic neurons in vivo: ultrastructure, and quantitative determinations of catecholamines and somatostatin

The ultrastructural and transmitter development of lumbar sympathetic ganglia was studied in embryonic day-6 through -18 chick embryos. At embryonic day 6, ganglia are populated by two morphologically distinct types of neuronal cells and Schwann cell precursors. The neuronal populations basically comprise a granule-containing cell and a developing principal neuron. Granule-containing cells have an irregularly shaped or oval nucleus with small clumps of chromatin attached to the inner nuclear membrane and numerous large (up to 300 nm) membrane-limited granules. Developing principal neurons display a more rounded vesicular nucleus with evenly distributed chromatin, prominent nucleoli, more developed areas of Golgi complexes, and rough endoplasmic reticulum and large dense-core vesicles up to 120 nm in diameter. There are granule-containing cells with fewer and smaller granules which still display the nucleus typical for granule-containing cells. These granule-containing cells may develop toward developing principal neurons or the resting state of granule-containing cells found in older ganglia. Both granule-containing cells and developing principal neurons proliferate and can undergo degeneration. At embryonic day 9 there are far more developing principal neurons than granule-containing cells. Most granule-containing cells have very few granules. Mitotic figures and signs of cell degeneration are still apparent. Synapse-like terminals are found on both developing principal neurons and granule-containing cells. Ganglionic development from embryonic day 11 through 18 comprises extensive maturation of developing principal neurons and a numerical decline of granule-containing cells. Some granule-containing cells with very few and small granules still persist at embryonic day 18. The mean catecholamine content per neuron increases from 0.044 femtomol at embryonic day 7 to 0.22 femtomol at embryonic day 15. Concomitantly, there is a more than 6-fold increase in tyrosine hydroxylase activity. Adrenaline has a 14% share in total catecholamines at embryonic day 15. Somatostatin levels are relatively high at embryonic day 7 (1.82 attomol per neuron) and are 10-fold reduced by embryonic day 15. Our results suggest the presence of two morphologically distinct sympathetic neuronal precursors at embryonic day 6: one with a binary choice to become a principal neuron or to die, the other one, a granule-containing cell, which alternatively may develop into a principal neuron, acquire a resting state or die.

Neuronal pathways in the guinea-pig lumbar sympathetic ganglia as revealed by immunohistochemistry

Tyrosine hydroxylase (TH)- and peptide-immunoreactivity of postganglionic neurons and of nerve fibres in guinea pig lumbar paravertebral sympathetic ganglia 2-4 after transection of the communicating rami and the visceral branches, respectively, were investigated by single- and double-labelling techniques. Six subpopulations of postganglionic neurons were discriminated immunohistochemically: two cell types, which were immunoreactive to only one of the applied antisera - TH, and vasoactive intestinal polypeptide (VIP); and four cell types in which immunoreactivity was colocalized - TH/neuropeptide Y (NPY), NPY/VIP, dynorphin/alpha-neoendorphin and dynorphin (alpha-neoendorphin)/NPY. Small intensely fluorescent (SIF) cells dependent on their location exhibited differential immunobehaviour to NPY-/dynorphin-(alpha-neoendorphin-) and TH-antisera. Immunoreactivity to substance P (SP), calcitonin gene-related peptide (CGRP), met-enkephalin-arg-phe (MEAP) and leu-enkephalin was present in nerve fibres but not in postganglionic neurons with frequent colocalization of SP/CGRP- and MEAP/leu-enkephalin- and, sometimes leu-enkephalin/SP- and dynorphin/SP-immunoreactivity. TH-immunoreactive intraganglionic nerve fibres were numerically more increased after cutting the visceral branches, than after transection of the communicating rami. Vice versa, NPY-, VIP-, dynorphin- and alpha-neoendorphin-immunoreactive nerve fibres were particularly increased in number after cutting the communicating rami. Many but not all of the nerve fibres exhibited colocalization of two of these peptides. SP-, CGRP-, and enkephalin-immunoreactive nerve fibres were not visibly affected by cutting the visceral branches but virtually disappeared after lesioning the communicating rami.

Structural and functional aspects of acetylcholine peptide coexistence in the autonomic nervous system

The present article is an attempt to briefly review acetylcholine and peptide coexistence in the ANS. For more detailed information the reader is referred to the book by Furness and Costa (1987) and books edited by Elfvin (1983) and Björklund et al. (1988). Acetylcholine is the "classical" transmitter substance between preganglionic and post-ganglionic neurons in both the sympathetic and parasympathetic nervous system but also between postganglionic parasympathetic neurons and effector cells. ENK and NT were early on shown to be present in preganglionic sympathetic neurons whereas SP and SOM have more recently been associated with these cells. Physiological experiments have shown that ENK may presynaptically inhibit cholinergic transmission in sympathetic ganglia. The cholinergic postganglionic parasympathetic neurons contain VIP/PHI. These peptides may be responsible for the atropine-resistant vasodilation seen after stimulation of parasympathetic nerves. In salivary glands VIP has been shown to potentiate the salivatory volume response to ACh. A number of postganglionic sympathetic neurons innervating exocrine sweat glands in the skin are also cholinergic. In addition to VIP/PHI, these neurons contain CGRP and probably also SP. The functional significance of acetylcholine coexisting with four vasodilatory peptides in this cell population is at present unclear. In the enteric ganglia the coexistence situation is very complex. Thus, in the myenteric plexus cholinergic SP-containing excitatory motor neurons seem to be present. In the myenteric plexus other cholinergic neurons may contain at least six different neuronal peptides. These latter neurons seem to be part of the peripheral intestino-intestinal reflex arc which is involved in regulation of gastrointestinal motility and mucosal functions. In the submucous plexus three populations of cholinergic neurons are present, one of which has secretomotor properties and contains CGRP, CCK, GAL, NPY and SOM. In vivo and in vitro studies have shown that developing sympathetic neurons can "change" the "classical" transmitter they-use and alter their neuropeptide expression. If dissociated sympathetic neurons are grown in cultures without any non-neuronal elements they differentiate into a noradrenergic phenotype. However, if the cultures also contain non-neuronal cells, both noradrenergic and cholinergic properties will develop. These changes may also by induced by a conditioned medium, containing a diffusible factor secreted from the non-neuronal cells. In conclusion, the present article underlines the complexity of the chemical neuroanatomy of the ANS and emphasizes the abundance of the peptides in both noradrenergic and cholinergic neurons. Although these peptides can be shown to exert a number of interesting effects in various experimental paradigms, much work is needed to define their exact role in nervous system function.

Target influences on transmitter choice by sympathetic neurons developing in the anterior chamber of the eye

In contrast to the majority of sympathetic neurons which are noradrenergic, the sympathetic neurons which innervate sweat glands are cholinergic. Previous studies have demonstrated that during development the sweat gland innervation initially contains catecholamines which are lost as cholinergic function appears. The neurotransmitter phenotype of sweat gland neurons further differs from the majority in that they contain vasoactive intestinal peptide (VIP) rather than neuropeptide Y (NPY). In the experiments described here, we addressed the question of whether sympathetic targets influence the neurotransmitter-related properties of the neurons which innervate them; in particular, do sweat glands play a role in reducing the expression of noradrenergic properties and inducing the expression of cholinergic properties and VIP in sympathetic neurons? This was accomplished by cotransplanting to the anterior chamber of the eye of host rats the superior cervical ganglia (SCG) which contains neurons that normally innervate targets other than the sweat glands and differentiate noradrenergically and footpad tissue from neonatal rats. Sweat glands developed in the transplanted footpad tissue and became innervated by the cotransplanted SCG neurons. The transplanted neurons and sweat gland innervation initially exhibited catecholamine histofluorescence which declined with further development in the anterior chamber. After 4 weeks, choline acetyltransferase (ChAT) and VIP immunoreactivities were evident. These observations suggest that as in the neurons which innervate the glands in situ, noradrenergic properties were suppressed and cholinergic function was induced in the neurons which innervated the glands in oculo. To distinguish a specific influence of the sweat glands on transmitter choice, SCG were also cotransplanted with the pineal gland, a normal target of the ganglion. Neurons cotransplanted with the pineal gland continued to exhibit catecholamine histofluorescence and contained NPY immunoreactivity. At least some neurons in SCG/pineal cotransplants, however, developed ChAT immunoreactivity. The target-appropriate expression of catecholamines and peptides in these experiments is consistent with the hypothesis that some transmitter properties are influenced by target tissues. The indiscriminant expression of ChAT, however, suggests that at least in oculo, additional factors can influence transmitter choice.

Substance P mRNA is present in a population of CGRP-immunoreactive cholinergic postganglionic sympathetic neurons of the cat: evidence from combined in situ hybridization and immunohistochemistry

A synthetic oligonucleotide probe, complementary to a sequence of the rat beta-preprotachykinin mRNA coding for part of the mature substance P (SP), was used to localize, by in situ hybridization, SP mRNA to individual paravertebral sympathetic ganglion cells of the cat. Subsequent immunohistochemical analysis revealed that most of these neurons contained immunoreactivity to calcitonin gene-related peptide (CGRP), suggesting that they belong to the cholinergic cell population of the scattered type. These cells contain, in addition to SP and CGRP, vasoactive intestinal polypeptide and peptide histidine isoleucine.

Perivascular innervation of the mesenteric artery in spontaneously hypertensive rats

Perivascular innervation of the mesenteric arteries of 7-week-old and 6-month-old spontaneously hypertensive rats and normotensive Wistar-Kyoto rats was examined. The densities of neuropeptide Y-containing nerve fibers and adrenergic nerve fibers were increased in the distal regions of mesenteric arteries of spontaneously hypertensive rats as compared with findings in Wistar-Kyoto rats. However, the densities of cholinergic nerve fibers, vasoactive intestinal polypeptide-containing, and substance P-containing nerve fibers in the mesenteric arteries of the spontaneously hypertensive rats were unchanged in comparison with findings in the Wistar-Kyoto rats. Thus, not only adrenergic nerve fibers but also neuropeptide Y-containing nerve fibers may play an important role in the development and maintenance of hypertension in spontaneously hypertensive rats.

Fixation and demineralization of bone tissue for immunohistochemical staining of neuropeptides

The present study in the rat demonstrates the feasibility of applying immunohistochemical staining techniques on bone tissue for studies of substances such as neuropeptides contained in nerve fibers. Two fixation procedures, as well as the influence of demineralization on neuropeptide antigenicity, were studied in bone and for comparison in small intestine. In vivo perfusion with paraformaldehyde and picric acid, followed by demineralization in a solution of either EDTA-cacodylate or buffered EDTA-sucrose, proved to be the most appropriate with respect to preserved antigenicity. Antibodies to 23 neuronally related substances were tested. In the bone tissue, immunoreactivity was found to four neuropeptides: substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, and neuropeptide Y, and also to the catecholamine-synthesizing enzyme tyrosine hydroxylase. The described method for identifying intraosseal neuropeptides offers a new means of studying skeletal innervation and bioactive substances in bone tissue.

Vasoactive intestinal peptide distribution and colocalization with dopamine-beta-hydroxylase in sympathetic chain ganglia of pig

The extent to which vasoactive intestinal peptide (VIP) occurs in postganglionic cells of the sympathetic chain and whether these cells are noradrenergic, cholinergic, or neither is unknown. We have (1) established the extent of VIP-containing cell bodies and fibers in all levels of the sympathetic chain in pig and (2) determined the coexistence of VIP and dopamine-beta-hydroxylase (DBH) using immunofluorescence. Weanling pigs were perfusion fixed. Alternate serial frozen sections of cervical, thoracic and lumbar paravertebral ganglia were processed for immunofluorescence with antisera to VIP or DBH. VIP-immunoreactive cells were most evident in thoracic ganglia with a few occurring in stellate and lumbar ganglia. While the cells were distributed throughout individual thoracic ganglia, intensely stained cells consistently occurred just proximal to exiting fiber bundles and sent long processes into these bundles. VIP-immunoreactive fibers occurred in all ganglia. Fiber density varied at each level. Varicose fibers with VIP staining were found to be especially evident from the caudal cervicothoracic ganglion through upper lumbar ganglia, in many cases forming networks of beaded varicosities around principal ganglion cells. Fibers and cells were associated with both interganglionic connectives and rami. A majority of neurons in all ganglia were DBH-immunoreactive but with varying intensities. VIP- and DBH-immunoreactivity coexisted in the same perikarya in some cells in thoracic ganglia, preferentially in cells moderately DBH-immunoreactive. We conclude that VIP-immunoreactive cells are distributed primarily in the thoracic sympathetic chain ganglia and that fibers containing VIP are found at all ganglia levels. Additionally, some VIP-immunoreactive postganglionic neurons in paravertebral ganglia may be noradrenergic.

Depletion of cutaneous nerves and neuropeptides in diabetes mellitus: an immunocytochemical study

Immunocytochemistry for the general neuronal marker protein gene product 9.5 and four neuropeptides (calcitonin gene-related peptide, substance P, vasoactive intestinal polypeptide and neuropeptide Y) was performed on 20 skin biopsy specimens from 19 diabetic patients, age range 20-75 years, 17 Type 2 (non-insulin-dependent) and 3 Type 1 (insulin-dependent). Fifteen specimens were from the lower limb, 3 from the upper limb and 2 from the abdominal wall. Seven subjects had lower limb neurophysiological tests. All but one specimen showed reduced protein gene product 9.5 and neuropeptide immunoreactivity. Reduced protein gene product 9.5 and neuropeptide immunoreactivity was found in specimens taken from the abdominal wall and hand as well as those from the leg, and also in specimens from patients undergoing amputation for peripheral vascular disease. In general, the greater the number of abnormal neurophysiological tests, the greater the extent of neuronal abnormalities. Three patients with normal tests had abnormalities of dermal innervation. While these changes are also found in other axonal neuropathies, in the absence of other causes of peripheral nerve disease and of macrovascular disease, immunocytochemistry of skin biopsies may have a role in the assessment of diabetic neuropathy and its response to treatment.

Early expression of acetylcholinesterase activity in functionally distinct neurons of the zebrafish

The first expression and distribution of acetylcholinesterase (AChE) activity was studied among a distinct population of early neurons in embryonic zebrafish by using histochemical and retrograde labeling techniques. AChE first appeared in the nervous system in the primary motoneurons of the rostral spinal cord when the embryo had nine somites, approximately 14 hours postfertilization. Subsequent expression of AChE activity in the spinal cord proceeded in a rostral-to-caudal sequence. Cranial neurons expressed AChE activity shortly after it appeared in the rostral spinal cord. Several hours later, near the end of the first day, primary neurons in the hind-brain and spinal cord all contained AChE, including sensory neurons, reticulospinal interneurons, and primary motoneurons. AChE activity was also detected in the nucleus of the medial longitudinal fasciculus. Presumptive cranial ganglia transiently expressed AChE activity between 14 and 24 hours of development. These results, combined with previous observations that examined the time of origin and axogenesis of primary neurons, suggest that primary neurons in the embryonic zebrafish contain AChE before they sprout axons. The primary neurons appear to follow a common sequence of development consisting of a withdrawal from the cell division cycle, the expression of AChE, and axogenesis. Although this sequence is followed by all primary neurons, lack of a rostral-to-caudal sequence in the time of birth and variability in the time of axon outgrowth demonstrate that the relative timing of these three events is not rigidly programmed in individual neurons. Moreover, the very early expression of AChE in such diverse cell types suggests that it may have a developmental role in addition to its function in transmitter metabolism.

NPY-, galanin-, VIP/PHI-, CGRP- and substance P-immunoreactive neuronal subpopulations in cat autonomic and sensory ganglia and their projections

The neuronal subpopulations in the cat stellate, lower lumbar and sacral sympathetic ganglia were studied with regard to the cellular distribution of immunoreactivity to tyrosine hydroxylase (TH), acetylcholinesterase (AChE) and various neuronal peptides. Coexistence of neuropeptide Y (NPY)- and galanin (GAL)-like immunoreactivity (LI) was found in a high proportion of the neuronal cell bodies; these cells also contained immunoreactivity to TH, confirming their presumably noradrenergic nature. Some TH- and GAL-immunoreactive principal ganglion cells lacked NPY-LI. Two populations (scattered and clustered) of vasoactive intestinal polypeptide (VIP)- and peptide histidine isoleucine (PHI)-positive cell bodies were found in the sympathetic ganglia studied. The scattered VIP/PHI neurons also contained AChE-LI, calcitonin gene-related peptide (CGRP)-and, following culture, substance P (SP)-LI. The clustered type only contained AChE-LI. In the submandibular and sphenopalatine ganglia, neurons were AChE- and VIP/PHI-immunoreactive but lacked CGRP- and SP-LI. Many GAL- and occasional TH-positive neurons were found in these ganglia. In the spinal ganglia, single NPY-immunoreactive sensory neuronal cells were observed, in addition to CGRP- and SP-positive neurons. The present results show that there are at least two populations of sympathetic cholinergic neurons in the cat. Retrograde tracing experiments indicate that the scattered type of cholinergic neurons contains four vasodilator peptides (VIP, PHI, CGRP, SP) and provides an important input to sweat glands, whereas the clustered type (containing VIP and PHI) mainly innervates blood vessels in muscles.