The distribution and colocalization of neuropeptides in perivascular nerves innervating the large arteries and veins of the snake,Elaphe obsoleta

Summary Single- and dual-labelling immunohistochemistry were used to determine the distribution and coexistence of neuropeptides in perivascular nerves of the large arteries and veins of the snake, Elaphe obsoleta, using antibodies for vasoactive intestinal polypeptide, substance P, calcitonin gene-related peptide, neuropeptide Y, galanin, somatostatin, and leu-enkephalin. Blood vessels were sampled from four regions along the body of the snake: region 1, arteries and veins anterior to the heart; region 2, central vasculature 5 cm anterior and 10 cm posterior to the heart; region 3, arteries and veins in a 30-cm region posterior to the liver; and region 4, dorsal aorta and renal arteries, renal and intestinal veins, 5–30 cm cephalad of the vent. A moderate to dense distribution of vasoactive intestinal polypeptide-like immunoreactive fibres was found in most arteries and veins of regions 1–3, but fibres were absent from the vessels of region 4. The majority of vasoactive intestinal polypeptide-like immunoreactive fibres contained colocalized substance P-like immunoreactivity, and these fibres were unaffected by either capsaicin or 6-hydroxydopamine (6-OHDA) pretreatment. In the anterior section of the snake, the vagal trunks contained many cell bodies with colocalized vasoactive intestinal polypeptide and substance P-like immunoreactivity. It is suggested that the vasoactive intestinal polypeptide/substance P-like immunoreactive cell bodies and fibres are parasympathetic postganglionic nerves. Neuropeptide Y-like immunoreactive fibres were observed in all arteries and veins, being most dense in regions 3 and 4. The majority of these fibres also contained colocalized galanin-like immunoreactivity, and were absent in tissues from 6-OHDA pretreated snakes, suggesting that neuropeptide Y and galanin are colocalized in adrenergic nerves. A small number of neuropeptide Y-like immunoreactive fibres contained vasoactive intestinal polypeptide but not galanin, and were unaffected by 6-OHDA treatment. All calcitonin gene-related peptide-like immunoreactive fibres contained colocalized substance P-like immunoreactivity, and these fibres were observed in all vessels, being particularly dense in the carotid artery and jugular veins. All calcitonin gene-related peptide/substance P-like immunoreactive fibres appeared damaged after capsaicin treatment suggesting they represent fibres from afferent sensory neurons. A sparse plexus of somatostatin-like immunoreactive fibres was observed in the vessels only from region 4. No enkephalin-like immunoreactive fibres were found in any blood vessels from any region. This study provides morphological evidence to suggest that there is considerable functional specialization within the components of the rat snake peripheral autonomic system controlling the circulation, in particular the regulation of venous capacitance.     

Vasoactive intestinal polypeptide-immunoreactive nerves in the pulmonary vasculature of the aquatic file snake Acrochordus granulatus

Summary The indirect immunofluorescence technique was used to determine the distribution of vasoactive intestinal polypeptide-immunoreactive and somatostatin-immunoreactive axons in the pulmonary vasculature of the aquatic file snake Acrochordus granulatus. A dense distribution of vasoactive intestinal polypeptide-immunoreactive axons was found on the common pulmonary artery, the anterior and posterior pulmonary arteries, and the smaller arteries branching to the lung. The density of these axons appeared greater in arterial preparations taken from more distal regions of the lung. The densest distribution of vasoactive intestinal polypeptide-immunoreactive axons was observed on the larger pulmonary veins in all regions of the lung. These axons were observed on the larger veins within the lung parenchyma but not on the smaller veins. Axons and cell bodies were observed in the vagal nerve trunks which run parallel to the pulmonary arteries and veins. In contrast, no somatostatin-immunoreactive axons were observed in any region of the pulmonary vasculature. It is proposed that the perivascular plexus of vasoactive intestinal polypeptide-immunoreactive axons may represent part or all of the vagal postganglionic innervation of the pulmonary vasculature.     

Innervation of the large arteries and heart of the toad (Bufo marinus) by adrenergic and peptide-containing neurons

Summary The innervation of the major arteries and heart of the toad (Bufo marinus) was examined by use of glyoxylic acid-induced catecholamine fluorescence and peptide immunohistochemistry. All arteries possessed a moderate to dense plexus of adrenergic axons, which also showed neuropeptide Y-like immunoreactivity (NPY-LI). Some adrenergic axons in the intracardiac vagal trunks showed NPY-LI, but the varicose adrenergic axons innervating the cardiac muscle of the atria and ventricle, and the coronary blood vessels did not display NPY-LI. About half of the nerve cell bodies in the anterior sympathetic chain ganglia with dopamine--hydroxylase-LI (DBH-LI) also contained NPY-LI. The nerve cell bodies with DBH-LI alone were generally larger (median diameter 30 m) than those with both DBH-LI and NPY-LI (median diameter 20 m). Some cell bodies showing DBH-LI alone were surrounded by boutons with NPY-LI but not DBH-LI. Axons that displayed simultaneously both substance P-LI (SP-LI) and calcitonin gene-related peptide-LI (CGRP-LI) also formed a plexus around all arteries studied, being particularly dense around the mesenteric and pulmonary arteries. These axons are most likely sensory since SP-LI was reduced by capsaicin treatment, and nerve cell bodies with both SP-LI and CGRP-LI were found in dorsal root ganglia and the vagal ganglion. A dense plexus of axons showing somatostatin-LI was located around the pulmonary artery and its main intrapulmonary branches. A few nerves with vasoactive intestinal polypeptide-LI were found around the dorsal aorta and pulmonary artery. No perivascular nerves with enkephalin-LI were observed. Reversed-phase, high-pressure liquid chromatography of acid extracts of the large arteries showed that the major peaks of NPY-LI and SP-LI coeluted with porcine NPY (1–36) and synthetic SP (1–11), respectively. Thus, the location and structure of these peptides in perivascular nerves has been highly conserved during vertebrate evolution.     

Calcitonin gene-related peptide-like immunoreactivity in nerve fibers in the human skin. Relation to fibers containing substance P-, somatostatin- and vasocactive intestinalpolypeptide-like immunoreactivity

Calcitonin gene-related peptide-like immunoreactivity was demonstrated in in sensory nerve fibers in the epidermis and dermis as free nerve endings and around blood vessels and hair follicles of the human finger pad and arm skin. The vast majority of the calcitonin gene-related immunoreactive fibers was shown to display also substance P-like immunoreactivity and a few fibers in the dermis were somatostatin positive. No fibers displaying both substance P and somatostatin-like immunoreactivity were found but a few substance P immunoreactive fibers in the dermis-epidermis region were found to contain also vasointestinal polypeptide-like immunoreactivity. In the sweat glands, abundant calcitonin gene-related peptide positive, but substance P negative, fibers were observed with a similar distribution pattern as the vasoactive intestinal polypeptide immunoreactive fibers and these fibers were suggested to be of sympathetic origin.     

Calcitonin gene-related peptide-like immunoreactivity in nerve fibers in the human skin

Summary Calcitonin gene-related peptide-like immunoreactivity was demonstrated in in sensory nerve fibers in the epidermis and dermis as free nerve endings and around blood vessels and hair follicles of the human finger pad and arm skin. The vast majority of the calcitonin generelated immunoreactive fibers was shown to display also substance P-like immunoreactivity and a few fibers in the dermis were somatostatin positive. No fibers displaying both substance P and somatostatin-like immunoreactivity were found but a few substance P immunoreactive fibers in the dermis-epidermis region were found to contain also vasointestinal polypeptide-like immunoreactivity. In the sweat glands, abundant calcitonin gene-related peptide positive, but substance P negative, fibers were observed with a similar distribution pattern as the vasoactive intestinal polypeptide immunoreactive fibers and these fibers were suggested to be of sympathetic origin.     

Adrenergic nerves and 5-hydroxytryptamine-containing cells in the pulmonary vasculature of the aquatic file snake Acrochordus granulatus

Summary The adrenergic innervation of the pulmonary vasculature of the file snake Acrochordus granulatus was examined by use of glyoxylic acid-induced fluorescence. Perivascular plexuses of blue-green fluorescent nerves are observed around the common pulmonary artery, the anterior and posterior pulmonary arteries, the arterioles leading to the gas exchange capillaries of the lung, the venules draining the lung, and the anterior and posterior pulmonary veins. Adrenergic nerves are also associated with the visceral smooth muscle of the lung septa and other tissues. Thus, adrenergic control of pulmonary blood flow may occur either at the common pulmonary artery or more regionally within the lung. Regional control of blood flow in the elongate lung of this snake may be important in matching pulmonary perfusion with the distribution of respiratory gas. Glyoxylic acid-histochemistry and immunohistochemistry revealed that populations of cells located in the common pulmonary artery contain the indoleamine 5-hydroxy-tryptamine. Many of the cells are intimately associated with varicose blue-green fluorescent nerves. It is proposed that the 5-hydroxytryptamine-containing cells may be involved in intravascular chemoreception.     

Calcitonin gene-related peptide immunoreactivity in airway epithelial cells of the human fetus and infant

Summary Calcitonin gene-related peptide-immunoreactive cells were identified within the epithelium of distal conducting airways in the human fetus and infant. Several peptides and amines, including calcitonin, have been identified previously within a specific population of airway epithelial cells. These cells, referred to as pulmonary neuroendocrine cells, are postulated to be airway chemoreceptors responsible for changes in ventilation and perfusion in response to changes in airway gas composition. Calcitonin gene-related peptide immunoreactive cells could be identified throughout the period of development studies (20 weeks gestation to 3 months of age), but were present in only limited numbers in less than 50% of individuals (n=23). In contrast, large numbers of calcitonin gene-related peptide immunoreactive cells were identified in 100% of infants (1–3 months, n=5) with bronchopulmonary dysplasia. The differential processing of mRNA transcribed from the calcitonin gene in neural and non-neural tissue suggests that calcitonin, rather than calcitonin gene-related peptide, is the primary product of translation in pulmonary neuroendocrine cells. However, considering the potent vasodilatory and bronchoconstrictive effects of calcitonin gene-related peptide, its presence in pulmonary neuroendocrine cells, even in small amounts, may be important in controlling pulmonary vaso- and/or bronchomotor tone. The presence of large numbers of calcitonin gene-related peptide immunoreactive cells in infants with bronchopulmonary dysplasia suggests that calcitonin gene-related peptide may be one further agent contributing to the pulmonary pathophysiology seen in this disease.     

Neuropeptides in the intestine of two teleost species (Oreochromis mossambicus,Carassius auratus): Localization and electrophysiological effects on the epithelium

Summary The presence of bioactive peptides in the gut and their possible electrophysiological effects on the intestinal epithelium were studied in two teleost species, the tilapia (Oreochromis mossambicus) and the goldfish (Carassius auratus). Vasoactive intestinal polypeptide-like immunoreactive nerve fibres were found beneath the intestinal epithelium of both species. Galanin-, metenkephalin-and calcitonin gene-related peptide-like immunoreactive nerve fibres were found exclusively in the mucosa of the tilapia. Both species had vasoactive intestinal polypeptide-, enkephalin- or neuropeptide Y-like immunoreactive endocrine cells; calcitonin gene-related peptide-like immunoreactive endocrine cells were additionally found in the tilapia. Somatostatin- and dopamine--hydroxylase-like immunoreactivities were not observed. Nerve cell bodies in the myenteric plexus of both species showed immunoreactivity for calcitonin gene-related peptide-, vasoactive intestinal polypeptide-, and galanin-like peptide. Enkephalin-like immunoreactive nerve cell bodies were present in the tilapia only. None of the peptides had a pronounced electrogenic effect. However, calcitonin gene-related peptide added to stripped intestinal epithelium of the tilapia, reduced the ion selectivity, and addition of galanin increased the ion selectivity. In goldfish intestine, both galanin and calcitonin gene-related peptide were without effect. Enkephalin counteracted the serotonin-induced reduction of the ion selectivity of the goldfish intestinal epithelium, but had no effect on the tilapia epithelium. In both species, vasoactive intestinal polypeptide reduced the ion selectivity of the intestinal epithelium, and neuropeptide Y induced an increase of the ion selectivity. Somatostatin showed no effect on the epithelial ion selectivity of either species. Tetrodotoxin did not inhibit the effects of the peptides studied. The changes in ion selectivity suggest that the enterocytes may be under the regulatory control of these peptides.     

Combined retrograde tracing and immunohistochemistry of trigeminal ganglion neurons projecting to gingiva or tooth pulps in the lower jaw of the cichlid Tilapia mariae

Rat trigeminal ganglion neurons projecting to the oral mucosa or to tooth pulps have different cell diameters and contain different chemical markers. In the present paper we examine whether trigeminal ganglion neurons sending axons to gingiva or tooth pulps in the lower jaw of the cichlid Tilapia mariae differ in a similar way. Retrograde tracing with fluorescent latex microspheres revealed labelled gingival and pulpal neurons in the caudal part of the trigeminal ganglion. The gingival neurons had a unimodal size distribution (peak 11 μm; range 8–14 μm) and the pulpal neurons exhibited a bimodal size distribution (peaks 12 and 25 μm; range 10–40 μm). Immunohistochemistry revealed a calcitonin gene-related peptide-like immunoreactivity in some 40% of the gingival neurons and a substance P-like immunoreactivity in 30%. Of the small pulpal neurons about 60% exhibited a calcitonin gene-related peptide-like immunoreactivity and 15% showed a substance P-like immunoreactivity. Of the large pulpal neurons some 70% exhibited a calcitonin gene-related peptide-like immunoreactivity. These neurons did not show a substance P-like immunoreactivity. In some animals a few trigeminal ganglion neurons showed a neuropeptide Y- or a vasoactive intestinal polypeptide-like immunoreactivity. Perikarya with a tyrosine hydroxylase- or a choline acetyl transferase-like immunoreactivity were not observed. We conclude that gingiva and tooth pulps in the lower jaw of T. mariae are innervated by trigeminal ganglion neurons, the cell diameters and neuropeptide contents of which differ in a pattern similar to that in the rat. Hence, this seems to represent a conserved evolutionary pattern.     

Innervation pattern of guinea pig pulmonary vasculature depends on vascular diameter

Haberberger, Rainer, Michael Schemann, Holger Sann, andWolfgang Kummer. Innervation pattern of guinea pig pulmonary vasculature depends on vascular diameter. J. Appl.Physiol. 82(2): 426-434, 1997.The pulmonaryvasculature is supplied by various neurochemically distinct types ofnerve fibers, including sensory substance P-containing and autonomicnoradrenergic, nitrergic, and cholinergic axons.Pharmacological experiments have suggested that various segments of thepulmonary vascular tree respond differently to the respectiveneuromediators. We, therefore, aimed to determine histochemically andimmunohistochemically for each of these neurochemically distinctperivascular axons their quantitative distribution along the vasculartree from the extrapulmonary trunks to the smallest intraparenchymalramifications in control guinea pigs(n = 5). Generally, arterialinnervation was more developed than that of veins. Along the arterialtree, noradrenergic and substance P-containing axons were ubiquitousfrom the pulmonary trunk to smallest intraparenchymal vessels, whereasnitrergic axons were practically restricted to large (>700-µm)extrapulmonary arteries. Cholinergic axons were regularly present atarteries down to 100 µm in diameter and innervated two-thirds ofsmall arteries (50-100 µm). The results demonstrate thatthe noradrenergic vasoconstrictor innervation extends throughout thepulmonary vascular system whereas the innervation pattern with varioustypes of vasodilator fibers changes with vascular diameter, parallel toknown pharmacological differences in cholinergic and nitrergicvasodilator effects.

     

Studies on the distribution of calcitonin gene-related peptide-like and substance P-like immunoreactivities in rat hind limb muscles

Summary The tibialis anterior, extensor digitorum longus and soleus muscles in the rat were examined with respect to the presence of calcitonin gene-related peptide-like as well as substance P-like immunoreactivity. In some of the motor endplates in these muscles, identified by staining for acetylcholinesterase activity, calcitonin gene-related peptide-like immunoreactivity was detected, but in others it was not. Calcitonin gene-related peptide-like immunoreactivity was found to coexist with substance-P-like immunoreactivity in nerve fibres located outside and inside the capsule of the muscle spindles, as well as in nerve fibres located in nerve fascicles. These fibres presumably represent sensory nerve fibres. Calcitonin gene-related peptide-like immunoreactivity, but not substance P-like immunoreactivity, was also detected, in cap-like structures located on the surface of the intrafusal muscle fibres in the polar regions of the spindles, structures which are likely to correspond to motor plate endings. The observations suggest that calcitonin gene-related peptide is heterogeneously present in the endplates of rat hind limb muscles, and gives for the first time immunohistochemical evidence for the presence of calcitonin gene-related peptide and substance P in the innervation of muscle spindles.     

Distribution and effects of neuropeptide Y, vasoactive intestinal peptide, substance P, and calcitonin gene-related peptide in human middle meningeal arteries: comparison with cerebral and temporal arteries.

A sparse to moderate supply of nerve fibers containing neuropeptide Y-like immunoreactivity (NPY-LI), vasoactive intestinal polypeptide (VIP-LI), substance P (SP-LI), and calcitonin gene-related peptide (CGRP-LI) was demonstrated in the walls of human middle meningeal arteries. Comparison with similar studies on human cerebral and temporal arteries indicated a similar distribution and density. The immunoreactive material in all three arterial regions was characterized by reversed-phase high pressure liquid chromatography (HPLC) and radioimmunoassay (RIA). The major peak of NPY-LI, VIP-LI, SP-LI, and CGRP-LI in each extract eluted approximately with the same elution volume as that of the corresponding synthetic analogues. The concentration of NPY in the middle meningeal arteries was lower as compared to the temporal arteries. Low concentrations of SP-LI and CGRP-LI were found in the middle meningeal arteries as compared to the cerebral arteries. In isolated ring segments of human middle meningeal and cerebral arteries, NPY caused vasoconstriction but did not potentiate the contractile response of noradrenaline. In the temporal artery, NPY did not induce contraction but potentiated the vasoconstrictor response to noradrenaline. Vasoactive intestinal polypeptide, peptide histidine methionine-27, SP, neurokinin A, and CGRP relaxed all three types of cephalic arteries. The peptide effects were not antagonized by propranolol, atropine, or cimetidine. Comparison of the responses to VIP and SP of vessels from the different regions showed a similar pattern of reactivity. The response to SP was slightly (p less than 0.05) more potent, whereas the responses to CGRP were less potent in the middle meningeal as compared to that in cerebral (p less than 0.005) vessels.     

Inhibition of periarterial nerve stimulation-induced vasodilation of the mesenteric arterial bed by CGRP (8-37) and CGRP receptor desensitization

We provide the first functional evidence that calcitonin gene-related peptide (8-37) induces a direct vasoconstriction and reversibly antagonizes vasodilation of the mesenteric arterial bed induced by calcitonin gene-related peptide (CGRP) suggesting that CGRP (8-37) is a competitive antagonist of vascular CGRP receptors. Vasodilation induced by periarterial nerve stimulation was inhibited both by CGRP (8-37) and by desensitization of CGRP receptors. These results further support the evidence that the periarterial nerve stimulation-induced nonadrenergic noncholinergic vasodilation of the mesenteric vasculature is mediated by endogenous CGRP and its receptors.     

Adrenergic innervation of the large arteries and veins of the semiarboreal rat snake Elaphe obsoleta

Fluorescence histochemistry was used to study the adrenergic innervation of the large arteries and veins at six points along the body of the semiarboreal rat snake Elaphe obsoleta. Apart from the vessels adjacent to the heart, there was a marked contrast in the density of adrenergic innervation of anterior and posterior systemic arteries and veins. The anterior arteries and veins have little adrenergic innervation in contrast to the extremely dense innervation of the arteries and veins posterior to the heart. The innervation pattern is consistent with known physiological adjustments to gravity and suggests a mechanism for regulating dependent blood flow via sympathetic nerves. In comparison to the posterior systemic arteries, parallel segments of pulmonary artery taken from the same body position of Elaphe contained a much sparser innervation by adrenergic nerves. The sparser innervation can be correlated with less gravitational disturbance in the pulmonary artery, which is relatively short in this and in other arboreal snakes.     

Changes in fibre populations of the rat hairy skin following selective chemodenervation by capsaicin

Perineural application of capsaicin results in a selective and permanent reduction in the sensitivity to noxious chemical and heat stimuli and elimination of the neurogenic inflammatory response. The present quantitative immunohistochemical study has been undertaken to reveal the populations of cutaneous afferent nerves that are affected by perineural capsaicin treatment. Areas of intact and chemodenervated skin were determined with the aid of the vascular labelling technique. In sections taken from intact skin areas, staining with antibodies against protein gene product 9.5 revealed a rich epidermal innervation. Fibres immunoreactive for growth-associated protein 43 were also abundant; nerve fibres immunoreactive for substance P and calcitonin gene-related peptide were less numerous. Somatostatin- and RT97-immunoreactive fibres were seen only in the subepidermal layer. In sections taken from skin areas supplied by the sciatic nerve treated with capsaicin 3 days previously, the number of epidermal nerve fibres immunoreactive to protein gene product 9.5, growth-associated protein 43, substance P and calcitonin gene-related peptide was reduced by 90%, 95%, 97% and 66%, respectively. These changes persisted for at least 42 days. The findings reveal that the majority of epidermal axons are capsaicin-sensitive and comprise a chemically heterogeneous population. Reductions in cutaneous fibre populations following perineural capsaicin treatment may result from both the degeneration of sensory axons and the depletion of neuron-specific macromolecules. In addition, most cutaneous nociceptive axons may not use the major sensory neuropeptides substance P and calcitonin gene-related peptide as afferent neurotransmitters.     

Calcitonin gene-related peptide vasodilation of human pulmonary vessels

Human calcitonin gene-related peptide (CGRP) is localized to sensory neurons in pulmonary vessels and is a potent vasodilator. We have characterized the effects of CGRP in human pulmonary vessels and localized the receptors for this peptide by autoradiography. Fresh human lung tissue was obtained from eight patients undergoing surgery and small (200-400 microns ID) pulmonary arteries and veins were dissected free of surrounding connective and pulmonary tissue. Pairs of vessels were studied and in one of each pair the endothelium was left intact and from the other of each pair the endothelium was removed by gentle abrasion. For functional studies arteries (n = 9) and veins (n = 9) were suspended in an organ bath, precontracted with 1 microM prostaglandin F2 alpha. CGRP (10 pM to 10 microM) was added in a cumulative manner. CGRP caused a dose-dependent relaxation of endothelium intact human pulmonary arteries and veins with log EC50 values of -8.01 +/- 0.35 and -8.70 +/- 0.40, respectively (not significant). Removal of the endothelium did not diminish the vasodilator potency of CGRP in either vessel. For autoradiographic studies, cryostat sections of the small human pulmonary vessels with or without endothelium were used. 125I-CGRP densely labeled CGRP receptors on vascular smooth muscle and endothelial removal did not have any effect on grain density. We concluded that CGRP is a potent vasodilator of human pulmonary arteries and veins that is not dependent on an intact endothelium. These functional studies correlate with the distribution of CGRP receptors as localized by autoradiography.     

The peptidergic innervation of the guinea pig uterine artery in pregnancy

The influence of pregnancy on the density and pattern of the peptidergic innervation of the guinea pig uterine artery was studied. Whole mount stretch preparations of the uterine artery from estrus and late pregnant guinea pigs were processed for the immunohistochemical demonstration of neuropeptide Y (NPY)-, vasoactive intestinal polypeptide (VIP)-, calcitonin gene-related peptide (CGRP)- and substance P (SP)- immunoreactive nerve fibres. In late pregnancy the density of NPY- and CGRP- containing nerve fibres was remarkably decreased, while that of VIP- and SP- immunoreactive nerves showed a moderate reduction. The meaning and the possible physiological relevance of the decreased density of peptide-immunoreactive nerves in the uterine artery in late pregnancy are discussed.     

Substance P-, CGRP- and NPY-immunoreactive nerve fibers in rat sciatic nerve-end neuromas

Substance P (SP)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-immunoreactive nerve fibers were examined in experimental sciatic nerve-end neuromas in the rat with immunohistochemical techniques. At 1-3 days after nerve ligation and section of the sciatic nerve there was an accumulation of SP-like immunoreactivity (SP-LI). Six days after the lesion there was, however, a marked reduction and the neuromas remained virtually depleted from SP-LI at survival times between 8 days and 3 months. CGRP-LI was strong at 1-5 days post-operatively. By 8 days, CGRP-LI was reduced, but a large number of axons were still immunoreactive, and remained immunolabelled up to 3 months. CGRP-LI nerve fibers formed endbulbs, and appeared to grow in both anterograde and retrograde directions. Fine fibers sprouts were first observed at 8 days, but preterminal branching in neuromas aged less than a month was uncommon. At early stages (1-3 days) after ligation, there was a marked accumulation of NPY-LI proximal to the nerve constriction. NPY-LI was reduced from 5 days and on, but many fibers remained NPY-positive and their growth pattern through proximal and distal neuroma segments could be determined. The present results thus may indicate a differential effect of nerve injury on neuropeptide expression: immunohistochemically detectable SP-LI rapidly disappears from sciatic nerve fibers trapped in nerve-end neuromas, but CGRP-LI and NPY-LI remain and are useful as neuroanatomical markers for two subclasses of sprouting axons. Furthermore, the findings suggest that both CGRP and NPY, but not SP, could be involved in ectopic electrical activity in experimental neuromas.     

Nerve growth factor receptor-like immunoreactivity in primary and permanent canine tooth pulps of the cat

Summary The distribution of nerve growth factor receptor (NGF receptor)-like immunoreactivity in pulps of developing primary and mature permanent cat canine teeth was examined, by use of a monoclonal antibody against NGF receptor detected by fluorescence immunohistochemistry and pre-embedding immunocytochemical light- and electron microscopy. Both primary and permanent pulps contained a vast number of NGF receptor-like immunoreactive nerves. Immunolabelling appeared to be localized both to axons and Schwann cells. In addition, many blood vessel walls in immature primary tooth pulps showed NGF receptor-like immunoreactivity, in contrast to permanent pulps where blood vessels rarely were NGF receptor-immunoreactive. Double-labelling immunofluorescence experiments revealed that in the permanent pulp a majority of the NGF receptor-positive nerves also showed calcitonin gene-related peptide (CGRP)-like immunoreactivity, and many showed substance P-like immunoreactivity. However, nerve fibers with neuropeptide Y-like immunoreactivity lacked NGF receptor-like immunoreactivity. In developing primary tooth pulps fewer NGF receptor-positive nerves were CGRP-like immunoreactive or substance P-like immunoreactive, as compared to the permanent pulp. Neuropeptide Y-like immunoreactive nerve fibers were not detected in the primary tooth pulp. The results suggest a role for nerve growth factor in both developing and mature sensory nerves of the tooth pulp.     

Motor innervation by enteric nerve fibers containing both nitric oxide synthase and galanin immunoreactivities in the striated muscle of the rat esophagus

The relationship between nitric oxide synthase (NOS)- and galanin-immunoreactive nerve terminals and the origin of NOS-immunoreactive nerve terminals on the motor endplates in the striated muscles of the rat esophagus was investigated. Double immunohistochemical staining revealed a dual innervation of motor endplates by calcitonin gene-related peptide (CGRP)-immunoreactive axons and by axons that were immunoreactive for both NOS and galanin. On average, 91% of NOS terminals were galanin immunoreactive. NOS-immunoreactive fibers were revealed at 67% of endplates, identified by the presence of CGRP terminals. The left vagus and superior laryngeal nerve were cut and 15 days allowed for terminals to degenerate. This caused a significant loss of CGRP fibers, but did not affect the density of innervation of the striated muscle by NOS-immunoreactive fibers. Thus the NOS/galanin fibers are deduced to originate from ganglia in the esophageal wall. This is supported by our observation of numerous NOS-immunoreactive nerve cell bodies in the myenteric ganglia of the esophagus, 74% of which were galanin immunoreactive. There were no CGRP-immunoreactive nerve cell bodies in the wall of the esophagus.