Vasoactive intestinal peptide-like immunoreactivity in nerves associated with the cardiovascular system of guinea-pigs

The distribution of nerves with vasoactive intestinal peptide (VIP)-like immunoreactivity has been examined in the heart and vascular system of guinea-pigs. There was a very sparse supply of fibres to the heart. No immunoreactive cell bodies were found in the intrinsic cardiac ganglia; however, positive nerve cell bodies were seen along the superior vena cava near the right atrium. There were immunoreactive fibres with most arteries; these fibres were located at the media-adventitia junction. The supply to major distributing arteries, such as the aorta, subclavian, carotid and femoral arteries as well as to the pulmonary arteries, was sparse. Of the individual vascular beds, the most densely supplied arteries were the mesenteric and uterine (or in the male deferential) arteries. Arteries running to other organs or tissues, such as skeletal muscle, kidney, pancreas, spleen and heart were less densely supplied. There were clear differences in the innervation of different cerebral vessels. The greatest density was associated with the anterior and middle cerebral arteries. Fewer nerves accompanied the posterior cerebral, cerebellar and meningeal arteries. There was a sparse innervation of the rostral part of the basilar artery. Throughout the body, veins were sparsely supplied. The distribution of nerves with VIP-like immunoreactivity was not changed when noradrenergic nerves were degenerated by 6-hydroxydopamine or when substance P nerves were disrupted by capsaicin. It is concluded that VIP containing nerves innervating the heart and blood vessels form a population distinct from the substance P-containing and the noradrenergic nerves. It is suggested that the VIP fibres might be efferent vasodilator nerves to the blood vessels.     

Distribution and possible origins of substance P-containing nerve fibers in the rat liver.

The distribution and possible origins of substance P-containing nerve fibers in the rat liver were investigated by immunohistochemistry and nerve transection. Nerve fibers with substance P-like immunoreactivity formed a more complex network than previously known in the walls of portal vein branches. Substance P-immunoreactive fibers were seen not only in and around the walls of the hepatic artery, but also in close association with the hepatic veins and bile ducts. Transection of the greater splanchnic nerves and/or the vagus nerves indicated that substance P-immunoreactive fibers in the walls of the portal and hepatic veins enter the liver via both nerves, and that those associated with the hepatic artery and bile ducts stem from the greater splanchnic nerves. The widespread distribution of hepatic substance P and its complex innervation pattern within the liver suggest that it is involved in a variety of physiological processes in this organ.     

Topographical localization of substance P in the human post-mortem brainstem. An immunohistochemical study in the newborn and adult tissue

The localization of substance P-immunoreactive nervous structures in the newborn and adult human brainstem is studied by the indirect immunofluorescence technique of Coons and collaborators. Substance P-containing perikarya, nerve fibres and terminals are widely and unevenly distributed in several areas of the human brainstem, with a location similar to that described in other mammals; however, some remarkable differences are detectable, which speak in favour of the existence of species differences. For example, in the human brain there is a dense plexus of substance P-immunoreactive fibres in the cuneate fasciculus. The use of the newborn tissue is very helpful in the detection of the immunoreactive neuronal cell bodies. The comparative study of the newborn and the adult tissue reveals that the distribution of the substance P-like immunoreactivity changes in man during ontogeny and results in a more complete map of the substance P-containing neuron system.     

Peptide containing nerves in the ureter of the guinea-pig and cat

We report the presence of two regulatory peptides, substance P and vasoactive intestinal polypeptide (VIP), in the ureter and their localisation by both light- and electron-microscopy to autonomic nerves. VIP- and substance P-like immunoreactive nerves showed, in general, a similar anatomical distribution in the various layers of the ureter. Immunoreactive nerves were observed running along the smooth muscle coat, parallel to muscle bundles, around blood vessels and in the submucosa, particularly beneath the epithelium. In addition, scattered VIP-like immunoreactive ganglion cells and nerve fibres were seen in adventitial ganglia around the most distal part of the ureter and ureter-bladder junction in the cat. The guinea-pig ureter contained principally substance P-like immunoreactivity, whereas the cat ureter possessed mainly VIP-like material.The distribution of adrenergic and cholinergic nerves was compared with those containing peptides. Peptide-containing nerves had a more extensive distribution than adrenergic ones, which were mainly associated with blood vessels; however, cholinergic nerves were often localised in the same areas as those possessing peptides. Conventional electron microscopy revealed that separate p-type (peptidergic) and cholinergic nerve terminals were frequently present in the same nerve bundles, although in the cat ureter some 50% of the p-type profiles contained a mixed population of vesicles, characteristic of both cholinergic and p-type nerves. VIP- and substance P-like immunoreactivity were also localised at the ultrastructural level by means of a gold-labelled goat-antirabbit serum.     

The distribution of substrate P-like immunoreactive nerves in the guinea-pig heart

We report the presence of substance P-like immunoreactivity in the guinea-pig heart and its localisation in varicose nerve fibres distributed throughout this organ. Immunoreactive fibres occurred in the atrial and ventricular walls, in the valve cusps, around the aorta and pulmonary vessels, coronary vessels and their branches. They were also associated with the conducting system and occurred around cardiac ganglion cells, but no immunoreactive neuronal cell bodies were seen. The distribution of substance P-like immunoreactive nerve fibres was compared with that of noradrenergic and acetylcholinesterase-stained nerves. Differences found in the number and distribution patterns of these nerves indicate that those immunostained with antiserum to substance P are, to some extent at least, distinct from the other two. The origin(s) and functional role(s) of these immunoreactive nerve fibres have yet to be established, but the findings are consistent with the view that substance P may be involved in regulating coronary blood flow and in modulating the neurotransmission of cardiac neurons.     

Comparative study on the innervation of nerves with calcitonin gene-related peptide, substance P and neurokinin A immunoreactivity in the walls of the cerebral arteries of small bats (Mammalia: Microchiroptera).

The distribution and origin of nerves with calcitonin gene-related peptide, substance P or neurokinin A immunoreactivity in the walls of the cerebral arteries were investigated in three microchiropteran species. The supply of nerves immunoreactive for substance P and neurokinin A to the bat cerebral arteries is confined mostly to the vertebral and basilar arteries. The density of innervation of calcitonin gene-related peptide-immunoreactive nerves and that of nerves with substance P or neurokinin A immunoreactivity in the vertebrobasilar system differ among species: the Japanese large footed bat is innervated with nerves with calcitonin gene-related peptide, substance P and neurokinin A immunoreactivity with about the same density, whereas in the greater horseshoe bat, there are many substance P-immunoreactive nerves with very weak or no calcitonin gene-related peptide immunoreactivity, and in the bent-winged bat, calcitonin gene-related peptide immunoreactivity is not found in all nerves with substance P immunoreactivity in the pial arteries of all parts of the brain. Nearly all cells immunoreactive for substance P, calcitonin gene-related peptide or both in the trigeminal and cervical dorsal root ganglia were small. In the greater horseshoe bat and the bent-winged bat, there is a correlation between the level of expression of substance P and calcitonin gene-related peptide immunoreactivity in the cervical dorsal root and trigeminal ganglia and the cerebral perivascular nerves supplying the vertebrobasilar system. The cerebrovascular innervation of nerves with substance P immunoreactivity in small bats is similar to that of cats and guinea-pigs in which the trigeminal ganglia have been destroyed. These observations, in addition to absence of nerve cells showing substance P or calcitonin gene-related peptide immunoreactivity in the pial artery and in the nerve bundles accompanying the extracranial internal carotid and vertebral arteries, suggest that substance P-immunoreactive nerves with or without immunoreactivity to calcitonin gene-related peptide in the vertebrobasilar system of small bats originate exclusively from the cervical dorsal root ganglia. The remaining fibres probably originate in the trigeminal ganglia.     

Innervation of human bone periosteum by peptidergic nerves

Nerves exhibiting substance P-like immunoreactivity were demonstrated in the human periosteum. A network of nerves showing substance P-like immunoreactivity was seen in the periosteum, while finer strands of immunoreactive nerve fibers were present immediately beneath the surface of the periosteum. Enkephalin-like immunoreactivity was also studied but could not be demonstrated. Substance P has previously been suggested to be involved in the mediation of the sensation of pain. The clinically observable marked pain sensitivity of periosteal tissue might be explained by the peptidergic nerves described in this paper.     

Some intrinsic neurons of the guinea-pig heart contain substance P

Whole-mount preparations of the posterior wall of the atria of the guinea pig heart containing intrinsic ganglion cells and nerve plexuses were stained for substance P-like immunoreactivity by the peroxidase-antiperoxidase method. Substance P-like nerve fibres are present as pericellular baskets around most, but not all, of the neuronal cell bodies, and are also found in the connecting nerve bundles, as perivascular nerve plexuses and in the myocardium and pericardium. The majority of ganglion cell bodies are negative for substance P, as reported previously, but we describe for the first time, a small subpopulation of intrinsic neuronal cell bodies which show immunoreactivity for substance P. Therefore, not all cardiac substance P nerves are extrinsic afferent fibres. At present, the physiological role of intrinsic substance P neurones is not clear.     

Sympathectomies lead to transient substance P-immunoreactive sensory fibre plasticity in the rat skin.

Research using animal models of neuropathic pain has revealed sympathetic sprouting onto dorsal root ganglion cells. More recently, sensory fibre sprouting onto dorsal root ganglion cells has also been observed. Previous work in our laboratory demonstrated persistent sympathetic fibre sprouting in the skin of the rat lower lip following sensory denervation of this region. Therefore, we applied immunocytochemistry to determine the effects of sympathectomies on the terminal fields of sensory fibres. The superior cervical ganglia were removed bilaterally and the effects on the innervation of the skin of the rat lower lip were observed 1, 2, 3, 4, 6 and 8 weeks post-surgery. Substance P and dopamine-beta-hydroxylase immunoreactivities were used to identify a subset of sensory and sympathetic fibres, respectively. We also assessed neurokinin-1 receptor immunoreactivity. Quantitative data was obtained with the aid of an image analysis system.In controls, the epidermis and upper dermis were innervated by substance P-immunoreactive fibres only and upper dermal blood vessels possessed the highest density of neurokinin-1 receptor immunoreactivity. Blood vessels in the lower dermis were innervated by both substance P- and dopamine-beta-hydroxylase-immunoreactive fibres. Following sympathectomies, substance P-immunoreactive fibres in the epidermis and upper dermis were more intensely labelled only 1 and 2 weeks post-surgery when compared to sham controls. The length of substance P-immunoreactive fibres in this region was also increased only on the second week. Neurokinin-1 receptor immunoreactivity in the upper dermis was slightly decreased 1 and 2 weeks post-surgery. In the lower dermis, substance P-immunoreactive fibres associated with blood vessels were more intensely labelled only 1 and 2 weeks post-surgery, and at all post-surgical time points studied, blood vessels in this region were devoid of dopamine-beta-hydroxylase-immunoreactive fibres. The length of substance P-immunoreactive fibres was increased from the first to the third week post-surgery in the lower dermis.These results indicate that sympathectomies lead to transient changes in substance P-immunoreactive fibre innervation and neurokinin-1 receptor expression in rat lower lip skin. The effects are most prominent in the lower dermis probably due to a greater local concentration of nerve growth factor in this region. The plasticity of the interactions between sensory and sympathetic fibres may prove important in the regulation of skin microcirculation and in the generation of painful sensations under normal conditions or following peripheral nerve injuries.     

Substance P neuronal organization in the median region of the interpeduncular nucleus of the cat: an electron microscopic analysis

The localization of substance P-like immunoreactivity in the interpeduncular nucleus using the peroxidase-antiperoxidase technique, revealed that the median region of the interpeduncular nucleus was one area rich in substance P-like immunoreactive processes. The ultrastructural characteristics of these substance P-like immunoreactive processes and their organization within the middle zone of the median region of the interpeduncular nucleus was studied. Substance P-like immunoreactivity was found in the perikaryon of small neurons, and in proximal and small dendrites. The substance P-like immunoreactive cell bodies and proximal dendrites receive a variety of unlabeled synaptic terminals. The immunoreactive small dendrites usually formed the central component of a "rosette"-like formation with unlabeled terminals. A few immunoreactive small unmyelinated axons and boutons were also present in the neuropil. The substance P-like immunoreactive boutons contained mainly small round vesicles with some large dense-core vesicles. These substance P-like immunoreactive boutons were presynaptic to unlabeled dendritic profiles, and frequently to substance P-like immunoreactive dendritic profiles. They were also seen in apposition to unlabeled boutons. Substance P-like immunoreactive boutons were not found to synapse with the crest-like dendritic processes in this part of the interpeduncular nucleus. It is suggested on the basis of morphological features, that some of the unlabeled terminals synapsing on substance P-like immunoreactive dendrities, may be cholinergic in nature.     

The origin and distribution of 5-hydroxytryptamine-like immunoreactive nerve fibres to major mesenteric blood vessels of the rat

5-Hydroxytryptamine-like immunoreactive nerve plexuses were demonstrated by indirect immunofluorescence histochemistry in whole-mount preparations and cryostat sections of blood vessels from the mesenteric vasculature of the adult rat. The major veins showed a density of innervation greater than that of the accompanying arteries. Removal of the coeliac-superior mesenteric ganglion complex resulted in almost total loss of 5-hydroxytryptamine-like immunoreactive nerves from superior mesenteric blood vessels. The results of crush lesions applied to distal vessels of the superior mesentery indicate that there were no 5-hydroxytryptamine-like immunoreactive nerve fibres extending from the enteric nervous system to these vessels. The administration of 6-hydroxydopamine resulted in a large reduction in the noradrenergic innervation, accompanied by a similar fall in the number of 5-hydroxytryptamine-like immunoreactive nerve fibres. It is suggested that the cell bodies of the 5-hydroxytryptamine-like immunoreactive nerve fibres demonstrated in the superior mesenteric vasculature are located within the sympathetic ganglia which supply the noradrenergic innervation to the same region and that the 5-hydroxytryptamine-like immunoreactivity may be co-localized with noradrenaline within sympathetic nerve fibres.     

Distribution of enteric neurons showing immunoreactivity for substance P in the guinea-pig ileum

Substance P-like immunoreactivity has been localized in whole mount preparations of the isolated layers of the guinea-pig ileum. Axons containing substance P formed dense networks around the nerve cells and ran in the primary, secondary and tertiary nerve bundles of the myenteric plexus. 3.6% of the nerve cell bodies of the myenteric plexus and 11.3% of the cell bodies in the submucous plexus showed immunoreactivity for substance P. Axons ran in fine nerve bundles parallel to the longitudinal muscle, between this muscle and the myenteric plexus. Axons containing substance P also ran in small nerve trunks parallel to the circular muscle throughout its thickness and in the deep muscular plexus at the base of this muscle coat. In the submucosa, these axons ramified amongst ganglion cells of the plexus and ran in the internodal strands. In addition they formed a perivascular network around submucous arteries and contributed to the paravascular nerves following these arteries. Axons containing substance P formed a delicate plexus in the mucosa. After extrinsic denervation the nerves containing substance P that were associated with submucous arteries, and some in the submucous plexus, disappeared. The nerves in the other areas were not detectably different from normal.Comparison with the distribution of somatostatin, enkephalin and vasoactive intestinal polypeptide indicated the neurons containing substance P constitute a separate population within the enteric nervous system.     

Substance P-like immunoreactive nerves in the anterior segment of the rabbit, cat and monkey eye

The indirect immunofluorescence technique demonstrates a substance P-like immunoreactive innervation to the anterior segment of the rabbit, cat and monkey eye. In all three species there is a sparse, but definite, corneal innervation. For the rabbit, substance P-like immunoreactive nerves to the aqueous outflow apparatus are found chiefly in the pectinate ligament. In the cat, this innervation is somewhat more extensive, being seen in the septae of the ciliary cleft as well. The monkey has a more plentiful innervation to the outflow apparatus than either the cat or the rabbit. Substance P-like immunoreactive nerves are visible in the trabecular meshwork and at the inner and outer walls of Schlemm's canal. For all three animals, the iris contains immunoreactive nerve fibers to the sphincter muscle, to the large blood vessels and to the anterior stromal melanocytes. In the ciliary body, the ciliary processes receive a constant innervation; it is somewhat more dense in the rabbit. Some of the large ciliary body blood vessels also are innervated. Ciliary body melanocytes are innervated; it was not possible to determine whether or not immunoreactive fibers innervate the ciliary muscle cells as well. The present study extends prior knowledge of the innervation of the eye. Taken with the known physiologic effects of substance P, it indicates a series of potential roles for this peptide in the vegetative processes of the eye.     

Substance P-like immunoreactivity in the retina and optic lobe of the squid

The distribution of substance P-like immunoreactivity within the squid retina and brain was studied by immunofluorescence. Positive immunoreactivity was observed as a single layer of fibres in the retina. The retina was devoid of tyrosine-hydroxylase, serotonin, gamma-aminobutyric acid, cholecystokinin, neuropeptide Y, somatostatin, enkephalin and vasoactive intestinal peptide immunoreactivities. Substance P immunoreactivity was particularly abundant in the optic lobe. The optic lobe had a distinct layer of substance P fibres near the periphery. Immunoreactive cell bodies, fibres and varicosities were additionally present in various areas of the optic lobe. Substance P immunoreactivity in the other ganglia of the brain was restricted to a few scattered fibres.     

Substance P-like immunoreactive fibers in the trigeminal sensory nuclei of the pit viper, Trimeresurus flavoviridis

Substance P-like immunoreactive nerve fibres were located in the trigeminal sensory system of the infrared-sensitive snake, Trimeresurus flavoviridis, using the immunohistochemical method. There are two trigeminal sensory systems in the medulla of this animal: the descending nucleus and the lateral descending nucleus. The descending nucleus is equivalent to the trigeminal spinal nucleus in other vertebrates, and the lateral descending nucleus is a special trigeminal sensory nucleus belonging to the infrared sensory system. In the present study we determined that the lateral descending nucleus is completely ensheathed by large numbers of substance P-like immunoreactive fibers. The distribution of these fibers seems to be similar to that of the thin vagal unmyelinated fibers, rather than to that of the thick trigeminal myelinated fibers. More substance P-like immunoreactive nerve fibers were observed in the lateral descending tract than in the descending tract. Almost no dense substance P-like immunoreactive fibers were found in these tracts rostral to the lateral descending nucleus or rostral to the subnucleus caudalis of the descending nucleus. The substance P-like immunoreactive fibers in the lateral descending tract extended to those of Lissauer's tract of the spinal cord, and the substance P-like immunoreactive fibers surrounding the Lissauer's tract were similar in appearance to those of the lateral descending nucleus. This nucleus seems to have developed from the elements existing in Lissauer's tract, and also to have a similar modulating function. The primary nucleus of the infrared sensory system is the most substance P-like immunoreactive nucleus in the trigeminal sensory system of this animal. Even in the trigeminal sensory system, substance P-like immunoreactive fibers seem not to be related solely to the nociceptive sensation.     

Immunohistochemical evidence for the presence of somatostatin-containing sensory nerve fibres in the human skin

Somatostatin-like immunoreactivity has been found to occur in nerve terminals and fibres of the normal human skin using immunohistochemistry. The immunoreactivity seemed predominantly to be associated with sensory nerves. Thus, nerve fibres displaying weak or moderately strong somatostatin immunofluorescence were observed as free nerve endings of the epidermis and as nerve fibres in the dermis. The immunoreactive nerves were found in low numbers in skin from arm, back and chest, however, only single fibres were seen in sensory specialized areas, such as fingertips. Very few fibres were found close to e.g. blood vessels and sweat glands. Somatostatin, generally believed to be a strongly inhibitory substance, should also be considered when examining the role of different sensory chemical messenger candidates in the human skin.     

Catecholaminergic and peptidergic nerves in naturally occurring and pheochromocytoma-associated human brown adipose tissue

Noradrenergic and peptidergic innervations in naturally occurring and pheochromocytoma-associated human perirenal brown adipose tissue were demonstrated. The presence of both parenchymal and periarterial noradrenergic nerve plexuses was revealed by the sucrose-potassium-glyoxylic-acid (SPG) technique in all tissue samples. Immunohistochemical studies also indicated the presence of neuropeptide Y-like, calcitonin gene-related peptidelike, substance P-like, and bombesinlike immunoreactive nerves in the adventitia of both inter- and intralobular arteries. At a more peripheral level, only neuropeptide Y-like immunoreactive elements were observed in the parenchymal field. No somatostatinlike or enkephalinlike immunoreactivity was detected. The specific distributions of noradrenergic and peptidergic nerves were similar in both naturally occurring and pheochromocytoma-associated brown adipose tissue. Thus these findings indicate a plurality of innervation in human perirenal brown fat.     

VIP nerve fibres around peripheral blood vessels

By immunocytochemistry nerve fibres containing vasoactive intestinal polypeptide (VIP) were demonstrated around many peripheral blood vessels in the cat. Such nerve fibres were particularly numerous around arteries in the upper respiratory, gastrointestinal and genito-urinary tracts. They were less numerous around large arteries and veins and seemed to be absent from blood vessels in the liver, spleen and kidney. VIP nerve fibres were few around blood vessels in skeletal muscle and absent in coronary arteries. Administration of VIP in vitro relaxed all arteries tested provided they had been given an increased tone, for instance by preincubation with PGF_2α. It is likely that VIP in vascular nerve fibres may participate in the regulation of systemic and local blood flow.     

Substance P-immunoreactivity in the dorsal medial region of the medulla in the cat: effects of nodosectomy

The distribution of substance P in the vagal system of the cat was studied by immunohistochemistry. Substance P-immunoreactive cell bodies and fibres were observed in the nodose ganglion. Numerous substance P-immunoreactive terminals and fibres were localized in their bulbar projection area, i.e. throughout the caudo-rostral extent of the nucleus of the solitary tract. Four subnuclei, among the nine forming the nucleus of the solitary tract, were strongly labelled: interstitial, gelatinosus, dorsal and commissural. The dorsal motor nucleus of the vagus nerve also exhibited numerous substance P-immunoreactive terminals, sometimes closely apposed on the somata of preganglionic neurons. To determine the substance P component of the vagal afferent system a nodose ganglion was removed on one side. The ablation triggered ipsilaterally a large decrease of substance P immunoreactivity in the four subnuclei strongly labelled on normal cats. These results suggest the involvement of substance P-containing vagal fibres in integrative processes of the central regulation of cardiovascular, digestive and respiratory systems, viscerotopically organized throughout these four subnuclei. The nodose ablation also resulted in a decrease of substance P immunoreactivity in the ipsilateral dorsal motor nucleus of the vagus nerve, suggesting monosynaptic vago-vagal interactions.     

Neural and glandular localisation of substance P inEchinostoma caproni (Trematoda-Digenea)

Immunocytochemical studies using antibodies against various peptides were performed onEchinostoma caproni. Only the presence of substance P or a related peptide was clearly demonstrated in this digenetic trematode. In the central nervous system, substance P-immunoreactive neurons were few and constituted two populations according to their size. Labelled axons were observed in the ventral and dorsal nerve cords. Scarce, small neurons and fibres were detected in the peripheral nervous system. The comparative study of 6- and 14-day-old worms showed an overall increase in substance P-immunoreactive nerve structures in the latter. Strong immunoreactivity for substance P was found in prostate cells from 14-day-old worms, whereas none was observed in 6-day-old worms. Thus, positive immunoreactivity seemed to be related to sexual maturity.