Substance P-immunoreactive Fibers Research Articles

Substance P-Immunoreactive Fiber Varicosities Appear to Innervate Galaninergic Perikarya in the Human Hypothalamus.

Introduction: Substance P (SP) is a member of the tachykinin family. In the central nervous system, SP participates among others, in the regulation of pain, learning, memory, emotion, and sexual functions. In the periphery, SP affects the gastrointestinal, cardiovascular, and urinary systems. Galanin, similarly to SP, appears to be involved in wide range of physiologic functions, including cognition, waking and sleep, feeding, mood, blood pressure, reproduction, and development, where acts as a trophic factor. The similar distribution of SP-immunoreactive (SP-IR) fibers and galanin-IR perikarya in the human hypothalamus suggests functional interaction between these neuropeptides. Methods: We have utilized double-label immunohistochemistry to reveal these putative juxtapositions. Results: The majority of galanin-IR neurons receive contacting SP-IR fibers that often cover a significant area of the galaninergic perikarya forming multiple en passant type contacts. These SP-galanin juxtapositions are located mainly in the basal part of the infundibulum/median eminence, populating the basal periventricular region as well as the basal perifornical area. Discussion: The density and the morphology of these associations suggest that these contacts are functional synapses and therefore may represent the morphological substrate of the control of SP on multiple functions regulated/modulated by galanin. SP via galanin may modulate anterior pituitary hormone secretion, as contrary to SP, high density of galanin immunoreactivity is present in the median eminence, and by innervating galanin-IR neurons projecting to other parts of the brain, SP can modulate indirectly their activities. Impact statement The present study is the first describing juxtapositions between the substance P (SP)-immunoreactive (IR) and galanin-IR neurons in the human hypothalamus. These juxtapositions may be functional synapses and they may represent the morphological substrate of the control of SP on the galaninergic system. SP via galanin may modulate anterior pituitary hormone secretion, as contrary to SP, high density of galanin immunoreactivity is present in the median eminence. Galanin, released into the hypothalamo-hypophyseal circulation, can reach the anterior pituitary and function as a hypophysiotropic substance and regulates anterior pituitary hormone secretion. SP by innervating galanin-IR neurons, which project to other parts of the brain, can modulate indirectly their activities.

A close neuroanatomical relationship between the enkephalinergic (methionine-enkephalin) and tachykininergic (substance P) systems in the alpaca diencephalon.

In the alpaca diencephalon, the distribution of immunoreactive cell bodies and fibers containing methionine-enkephalin (MET) or substance P (SP) has been studied. The immunohistochemical study was performed by standard method on the diencephalon of four male alpacas that lived at sea level. Nerve fibers containing MET or SP were widely distributed in the thalamus and hypothalamus. METand SP-immunoreactive fibers showed a similar distribution in the whole diencephalon. Immunoreactive cell bodies containing MET or SP were only observed in the hypothalamus. The distribution of MET-immunoreactive cell bodies was more widespread than that observed for cell bodies containing SP. A close neuroanatomical relationship between the tachykininergic (SP) and enkephalinergic (MET) systems was observed in the whole diencephalon suggestive of the existence of multiple physiological interactions between both systems.

Distribution of somatostatin-28 (1-12), calcitonin gene-related peptide, and substance P in the squirrel monkey brainstem: an immunocytochemical study.

Using an immunocytochemical technique, we have studied the distribution of fibers and cell bodies containing somatostatin-28 (1-12) [SOM-28 (1-12)], calcitonin gene-related peptide (CGRP), and substanceP (SP) in the brainstem of Saimiri sciureus. The distribution of the peptidergic cell bodies was very restricted: perikarya containing SOM-28 (1-12) were only observed in the substantia grisea centralis, while no immunoreactive cell bodies containing CGRP or SP were visualized. Fibers containing SOM-28 (1-12), CGRP, or SP were widely distributed in the brainstem: immunoreactive fibers containing SOM-28 (1-12) showed the most widespread distribution and were the most abundant. The distribution of SOM-28 (1-12)-, CGRP- or SP-immunoreactive fibers was very similar. Colocalization of immunoreactive fibers containing SOM-28 (1-12), CGRP or SP was observed in many brainstem nuclei. A neuroanatomical relationship between CGRP- and SP-immunoreactive fibers was observed, although this relationship was less marked for SOM-28 (1-12) and SP and lower still for SOM-28 (1-12) and CGRP. The widespread distribution of the peptidergic fibers suggests that the studied neuropeptides are involved in many physiological actions.

Differences in therapeutic effects of topically applied corticosteroid and tacrolimus on atopic dermatitis-like symptoms in NC/Nga mice

BackgroundTopical corticosteroid and calcineurin inhibitor have similar therapeutic benefits in atopic dermatitis (AD), but the differences in therapeutic mechanisms of action of these agents against AD symptoms are not fully understood. ObjectiveThis study was performed to examine the different effects of topical betamethasone valerate (BMV), clobetasol propionate (CBP), and tacrolimus (TAC) on itch-related behavior and dermatitis in NC/Nga mice with AD-like symptoms. MethodsAD-like dermatitis was induced in the dorsal skin of NC/Nga mice by repeated topical application of Dermatophagoides farinae body (Dfb) ointment twice weekly for three weeks. Mice with dermatitis scores over 5 were divided into five groups with equal dermatitis scores and treated with BMV, CBP, TAC, or Vaseline (Vas) once daily for two consecutive days, or were not treated (NT). Scratching behavior was analyzed using a SCLABA®-Real system. Transepidermal water loss (TEWL) before and after treatment was measured using a Tewameter® TM210. Skin collected from each group was analyzed histologically. ResultsAfter the second treatment, dermatitis showed significantly greater improvement in the CBP and TAC-treated groups than in the Vas-treated and NT groups. The numbers of scratching bouts were significantly lower in CBP and TAC-treated mice than in Vas-treated mice. TEWL was significantly lower in TAC-, but not in CBP-, treated mice than in Vas-treated mice. Immunohistochemical examination showed that BMV, CBP and TAC did not reduce the increased densities of epidermal protein gene product 9.5- and substance P-immunoreactive fibers. The numbers of dermal CD4-immunoreactive T cells were significantly lower in BMV and CBP-treated mice than in Vas-treated and NT mice. The numbers of dermal eosinophils were significantly lower in BMV, CBP and TAC-treated mice than in Vas-treated and NT mice, with CBP showing the strongest effect. CBP significantly reduced epidermal thickness compared with Vas and NT. There were no significant differences in the numbers of interleukin-31-immunoreactive cells and mast cells, or in expression of epidermal thymic stromal lymphopoietin among all five groups. ConclusionThe therapeutic potency of TAC against AD-like symptoms, including pruritus, is equal to that of the corticosteroid CBP. Epidermal innervation of sensory nerves itself might not be related to the therapeutic effects of topical tacrolimus and corticosteroids in its early phase.

Distribution and Origin of VIP-, SP-, and Phospholipase Cβ2 -Immunoreactive Nerves in the Tongue of the Bullfrog, Rana catesbeiana.

Previous studies have found a few intralingual ganglionic cells that were immunoreactive to vasoactive intestinal polypeptide (VIP) in the frog. A recent study reported a large number of such cells, and the possibility of the release of substance P (SP) from these. The aim of the present study was to investigate the distribution, origin, and colocalization of VIP- and SP- immunoreactive nerves in the tongue of the bullfrog, R. catesbeiana. In addition, the study also examined the colocalization of SP and phospholipase Cβ2 (PLCβ2 ) in the tongue and jugular ganglion. VIP immunoreactivity was seen in unipolar cells that were sparse in nerve bundles in the submucosal and muscle layers. The density of VIP-immunoreactive cells was approximately 4.8 cells/mm(3) . Their fibers terminated in the vicinity of the epithelial basal layer of the fungiform papillae. SP immunoreactivity was not seen in the VIP-immunoreactive cells, but was observed in pseudounipolar cells in the jugular ganglion. The SP fibers terminated close to the free surface, showing spindle- and button-like profiles. Transection of glossopharyngeal nerve resulted in the persistence of VIP-immunoreactive cells and the disappearance of SP-immunoreactive fibers in the tongue. SP immunoreactivity was co-expressed with PLCβ2 in both the tongue and jugular ganglia. No PLCβ2 immunoreactivity was seen in cells comprising the epithelial taste disk. These findings indicate that the origin of VIP nerve fibers are unipolar cells in the tongue, and SP and PLCβ2 fibers originate from pseudounipolar cells that may be able to release SP primarily in the jugular ganglion. Anat Rec, 299:929-942, 2016. © 2016 Wiley Periodicals, Inc.

Topical Application of Tenshino-Softgel<sup>TM</sup> Reduces Epidermal Nerve Fiber Density in a Chronic Dry Skin Model Mouse

Background: Dry skin induces antihistamine-resistant itch, as well as epidermal hyperinnervation, which is partly responsible for peripheral itch sensitization. In acute dry skin, topical application of emollients prevents the penetration of nerve fibers into the epidermis. However, the effects of emollients on itch and epidermal hyperinnervation in individuals with chronic dry skin are poorly understood. Objective: This study examined the effects of Tenshino-softgelTM (TSG) on itch-related behavior, epidermal hyperinnervation and skin barrier function in a chronic dry skin model mouse. Methods: Chronic dry skin was induced by application of acetone/ether (1:1) mixture and water (AEW) to the rostral parts of the back of hairless mice twice daily for six consecutive days. As treatment, TSG or, as control, Vaseline (V) was applied to the same areas twice daily. Skin barrier function was evaluated by measuring transepidermal water loss (TEWL) before each treatment. Scratching behavior was recorded and analyzed using a SCLABA&reg-real system, and skin samples were collected for immunohistochemical assays. Results: TEWL tended to be lower and scratching bouts fewer in AEW + TSG- than in AEW-treated mice. The numbers of protein gene product 9.5-immunoreactive fibers and substance P-immunoreactive fibers were each significantly lower in the epidermis of AEW + TSG- than of AEW-treated mice, but the expression of nerve growth factor in epidermis was similar in the three groups. Semaphorin 3A expression was significantly higher in the epidermis of AEW + TSG- than of AEW- and AEW + V-treated mice. Conclusion: Topical application of TSG may attenuate itch induced by chronic dry skin through a mechanism involving the inhibition of epidermal hyperinnervation.

Positive reinforcing effects of substance P in the rat globus pallidus revealed by conditioned place preference

Substance P (SP) may have positive reinforcing effects when injected into different brain structures. Immunohistochemical experiments showed the presence of SP-immunoreactive fibers and also its receptors in the globus pallidus (GP). According to recent experimental data the GP may be involved in reward-related processes. The aim of our study was to test possible rewarding consequences of pallidal SP in conditioned place preference (CPP) paradigm. Male Wistar rats, microinjected with 10 ng SP, showed place preference, while 100 ng SP had no such positive reinforcing effect. The possible involvement of NK1 receptors was also studied. Prior treatment with the NK1 receptor antagonist WIN 51,708 could block the rewarding effects of SP, while the antagonist on its own did not influence CPP behavior. Our results show that SP and its NK1 receptors play important roles in pallidal positive reinforcing mechanisms.

Positive reinforcing effects of substance P in the rat central nucleus of amygdala

Substance P (SP) can have positive reinforcing or aversive properties, depending on the dose used and the site of action in the brain. Experimental findings suggest that the amygdala is involved in reward-related processes. The presence of SP-immunoreactive fibers and cell bodies has been shown in the central nucleus (ACE) and neurokinin (NK)-1 and NK-3 receptors also could be found there. The rewarding or aversive effects of SP in the ACE were tested in conditioned place preference paradigm. 10 ng SP microinjections had positive reinforcing properties, while 100 ng SP had no effect. Prior treatment with NK-1 receptor antagonist could block the rewarding effects of SP, while the antagonist on its own did not influence place preference. Our results show that SP and NK-1 receptors play important roles in amygdaloid rewarding-reinforcing mechanisms.

Increased capsaicin receptor TRPV1-expressing sensory fibres in irritable bowel syndrome and their correlation with abdominal pain

Objective:The capsaicin receptor TRPV1 (transient receptor potential vanilloid type-1) may play an important role in visceral pain and hypersensitivity states. In irritable bowel syndrome (IBS), abdominal pain is a common...

A New Model of Laryngitis: Neuropeptide, Cyclooxygenase, and Cytokine Profile

To develop and characterize a new model of laryngeal inflammation by analyzing the presence of neurogenic peptides and expression of cyclooxygenases (COX) and cytokines in the mucosa. Laryngitis induced by nasogastric intubation (NGI) was evaluated by histopathologic changes of the mucosa, alterations in calcitonin gene related peptide (CGRP) and substance P (SP) neuropeptides in sensory fibers, and COX-1,2, and cytokine (interleukin [IL]-1, IL-6, IL-10, tumor necrosis factor [TNF]-[alpha]) expression in the laryngeal mucosa. Rats submitted to NGI for 1 to 5 weeks were compared with controls. Laryngeal sections were immunostained for stereologic analysis of SP and CGRP fiber density and number of mucosal cells expressing COX-2. Alterations in inflammatory mediators were evaluated by quantitative reverse-transcriptase polymerase chain reaction. NGI induced metaplasia of the epithelium and narrowing of the laryngeal lumen because of hypertrophy of laryngeal glandules and edema. An initial decrease in CGRP- and SP-immunoreactive fibers in the laryngeal mucosa (1-3 wk) was reverted with time (5 wk). COX-2 expression in mucosal cells increased progressively, reaching a maximum level at 5 weeks, and was observed in mononuclear immune cells, which is indicative of a chronic inflammatory process. In regard to mRNA expression levels of inflammatory mediators, TNF-[alpha] was increased during the 5 week NGI, and IL-10 decreased during the 5 weeks,whereas IL-1[beta], IL-6, and COX-2 increased in the first 1 to 2 weeks and returned to baseline at 5 weeks. This NGI model results in laryngeal chronic inflammation without direct mechanical aggression of the mucosa and may contribute to the study of future therapeutic approaches to this pathology.

Neurokininergic Mechanism within the Lateral Crescent Nucleus of the Parabrachial Complex Participates in the Heart-Rate Response to Nociception

We wanted to ascertain whether the lateral parabrachial nucleus was involved in mediating the heart-rate response evoked during stimulation of somatic nociceptors. Reversible inactivation of the lateral parabrachial nucleus, using a GABA(A) agonist, reduced the reflex tachycardia evoked during noxious (mechanical) stimulation of the forelimb by approximately 50%. The same effect was observed after blockade of neurokinin 1 receptors within the lateral parabrachial nucleus, indicating a possible involvement for substance P as a neurotransmitter. Immunocytochemistry revealed a strong expression of substance P-immunoreactive fibers and boutons in all lateral subnuclei, but they were particularly dense in the lateral crescent subnucleus. Histological verification showed that the most effective injection sites for attenuating the noxious-evoked tachycardia were all placed in or near to the lateral crescent nucleus of the lateral parabrachial complex. Many single units recorded from this region were activated by high-intensity brachial nerve stimulation. The brachial nerve evoked firing responses of some of these neurons was reversibly reduced after local delivery of a neurokinin 1 receptor antagonist. However, only a minority of these neurons followed a paired-pulse stimulation protocol applied to the spinal cord, suggesting a predominance of indirect projections from the spinal cord to the parabrachial nucleus. We conclude that the cardiac component of the response to somatic nociception involves indirect spinal pathways that most likely excite neurons located in the lateral crescent nucleus of the parabrachial complex via activation of neurokinin 1 receptors.

Cholecystokinin and substance P immunoreactive projections to the paraventricular thalamic nucleus in the rat

Cholecystokinin (CCK) and substance P (SP) are thought to play an important role in a variety of stress responses. Both CCK- and SP-positive fibers innervating the thalamus are found principally in the midline nuclei, including the paraventricular thalamic nucleus (PVT), which has strong reciprocal connections with the medial prefrontal cortex. In the present study, we determined the source of the CCK- and SP-immunoreactive fibers to the PVT, employing combination of retrograde neuronal tracing and immunohistochemistry in the rat. The PVT-projecting neurons showing CCK immunoreactivity were detected in the dorsomedial nucleus of the hypothalamus, and ventral mesencephalic periaqueductal gray, including the Edinger-Westphal nucleus and the dorsal raphe nucleus. Sources of SP afferents to the PVT were detected in the Edinger-Westphal nucleus, the mesopontine tegmentum and the medullary raphe nucleus. CCK- and SP-immunoreactive fibers may exert modulatory influence on the prefrontal cortical activity via the PVT and regulate behavioral components of stress-adaptation responses.

Autonomic dysreflexia, induced by noxious or innocuous stimulation, does not depend on changes in dorsal horn substance p.

After experimental spinal cord injury (SCI) in rats, autonomic dysreflexia is commonly induced by slightly noxious cutaneous or visceral stimuli. The presence of autonomic dysreflexia is associated with an increase in the afferent fiber arbor area labeled by cholera toxin B or with an anti-CGRP antibody. Our goal was to examine further the sensory afferent input contributing to exaggerated autonomic spinal reflexes and subsequent increases in blood pressure after SCI, typical of autonomic dysreflexia. We observed that changes in blood pressure and heart rate induced by slightly noxious stimuli (2.0-mL balloon colon distension, cutaneous pinch) were increased in magnitude with time after SCI. In contrast, cardiovascular responses induced by non-noxious stimuli (1.0-mL balloon colon distension, light stroking of hair) were relatively constant. We examined substance P-immunoreactive afferent fibers to identify type C, unmyelinated afferent fibers, and A delta lightly myelinated fibers in superficial and deeper laminae of the dorsal horn, respectively. The area of substance P-immunoreactive fibers was quantified in laminae I-V of the dorsal horn. Analysis revealed no difference in substance P afferent fiber area in laminae I-II, or laminae III-V, between sham-injured and SCI rats. These data suggest that noxious, or innocuous, stimulation induces autonomic dysreflexia without expansion of the central arbors of substance P-immunoreactive sensory neurons. Furthermore, autonomic dysreflexia induced by noxious stimulation increases with time after spinal cord injury.

Intraepithelial nerve fibers project into the lumen of the larynx.

Studies on the morphology and location of the sensory receptors in the laryngeal mucosa have resulted in insufficient and sometimes conflicting data. In the present study the authors analyzed the distribution and morphology of sensory nerve plexuses and terminal fibers in the laryngeal mucosa of the rat. Two groups of Male Wistar rats were used in this laboratory study; the larynx of the first group were used to analyse the sensitive innervation of its epithelium, whereas the larynx of the second group (controls) were tested for the specificity of the antibodies used. The larynges of the animals were entirely removed after perfusion, and coronal or horizontal sections were immunoprocessed for further randomized analysis of the mucosa. Primary afferents were detected by immunoreaction to two widely recognized markers of sensory nerves, calcitonin gene-related peptide and substance P, and visualized using diaminobenzidine as a chromogen. The nerve plexuses were more densely distributed in the dorsal half of the vocal folds and in the laryngeal aspect of the epiglottis. Dense networks of fine fibers with many varicosities en passant, immunoreactive for both calcitonin gene-related peptide and substance P, occurred in the lamina propria and along the epithelial thickness. Calcitonin gene-related peptide-immunoreactive and substance P-immunoreactive fibers extended across the epithelium and projected to the laryngeal lumen itself, reaching the space between the cilia. The projection of intraepithelial nerve fibers into the lumen of the larynx indicates that in the absence of mucus, nerve endings may be exposed and thus receive direct stimulation from airborne substances. Furthermore, it suggests that the laryngeal mucosa of the rat may constitute an experimental model for studying the direct activation or manipulation of primary afferents at the periphery and neurogenic inflammation.

Effects of electroacupuncture on gastric myoelectric activity and substance P in the dorsal vagal complex of rats

Acupuncture has been widely applied to treat gastrointestinal diseases in the clinic. However, its precise mechanism remains unknown. In the present study, effects of electroacupuncture (EA) at Zusanli acupoints (ST36) on gastric myoelectric activity and substance P (SP) in the dorsal vagal complex (DVC) were observed. EA at ST36 significantly increased the frequency of slow waves and the frequency of the spike potentials superimposed on the slow waves, which persisted for 90 min after cessation of EA and was completely abolished after bilateral vagotomy. Meanwhile, the mean optical density of SP immunoreactive fibers in the DVC increased following EA. The results suggested that EA at ST36 promoted the gastric myoelectric activity, which was regulated by the vagus, and SP in the DVC may be involved in the excitatory effects. Furthermore, EA had a relative long-term post-effect. We presumed that DVC may be a supraspinal center in the effect of EA on gastric function.

Substance P immunoreactive nerve fibres in the domestic chick ankle joint before and after acute urate arthritis

Substance P immunoreactive (SP-IR) nerve fibres were identified using fluorescence immunohistochemistry and the length of the labelled individual nerve fibres was measured using confocal microscopy of whole mounts of the lateral wall of the ankle joint in 2-week-old domestic chicks. In the normal ankle there was an extensive network of SP-IR fibres in the synovial and subsynovial tissue of the joint capsule. Fours hours after injection of sodium urate into the joint space the joint was inflamed and there was a significant reduction in the labelled nerve fibres. These results demonstrate experimentally that painful gouty arthritis produces a neurogenic depletion of substance P from peripheral nerve fibres in the synovial and subsynovial tissue.

Specific innervation of aromatase neurons by substance P fibers in the dorsal horn of the spinal cord in quail.

The enzyme aromatase catalyzes the production of estrogens in the dorsal horn of the spinal cord where most of the nociceptive primary afferent fibers terminate. Numerous estrogen receptors are present in this area and the control of spinal aromatase activity is thought to play an important role in the estrogenic control of nociception. The coexistence of aromatase and nociceptive terminals suggests a role for aromatase cells in pain-related processes, but whether terminals releasing nociceptive neuropeptides (e.g., substance P) actually contact aromatase neurons is unknown and the factors that control spinal aromatase activity have not yet been identified. In the present study we analyzed by double-label immunocytochemistry the distribution in the Japanese quail spinal cord, of aromatase and of substance P or its receptor (neurokinin 1 receptor). All antigens were mainly localized in laminae I and II as observed in mammals. Most aromatase neurons were colocalized with neurokinin 1 receptors and were in close apposition with substance P-immunoreactive fibers. These results suggest that aromatase neurons are responsive to noxious stimulation and may participate in the control of nociception. Furthermore, spinal aromatase activity could be controlled by substance P through a regulation of the aromatase gene transcription as reported for the mouse diencephalon and/or through neurokinin 1 receptor-dependent phosphorylation of the aromatase protein.

Sympathectomy causes increased root resorption after orthodontic tooth movement in rats: immunohistochemical study.

Accumulating evidence suggests that the sympathetic nervous system modulates inflammatory responses and bone remodeling. We have studied the effects of sympathectomy and orthodontic tooth movement (OTM) on root resorption, immunocompetent cell recruitment, neuropeptide, neurokinin-1 receptor (NK1-R), and interleukin 6 (IL-6) expression. Experimental rats (n=8) had the right superior cervical ganglion surgically removed, whereas control rats (n=6) underwent sham surgery. Three days later, all rats had the right maxillary first molar moved mesially by an orthodontic appliance. The rats were perfused 13 days later, and the right maxillae were processed for immunohistochemistry by using primary antibodies directed against ED1 antigen, CD43, substance P (SP), NK1-R, neuropeptide Y (NPY), and IL-6. Following OTM, sympathectomized (SCGx) rats had significantly more root resorption (P<0.01) and SP-immunoreactive (IR) fibers (P=0.01) in the compressed periodontal ligament (PDL) compared with control rats. There was a significant decrease in recruitment of CD43+ cells in the pulp after OTM in SCGx rats compared with control rats (P=0.02). An upregulation of NK1-R immunoreactivity was observed surrounding the hyalinized tissue, and an increase in the number of NK1-R IR cells and density of SP-IR fibers was present in first molar pulp of all rats. NPY-IR fibers were absent in the compressed PDL of SCGx and control rats. Thus, OTM induces remodeling not only around the periodontal tissues, but also in the dental pulp. The sympathetic nerves have an inhibitory effect on hard tissue resorption and a stimulatory effect on CD43+ cell recruitment after OTM.

Antiemetic effect of a tachykinin NK 1 receptor antagonist GR205171 on cisplatin-induced early and delayed emesis in the pigeon

Cisplatin (4 mg/kg, i.v.) induced both early emesis, which appears within the first 8-h period, and delayed emesis, which appears between 8 and 48 h after its administration to pigeons. GR205171 ([(2 S- cis)- N-((2-methoxy-5(5-(trifluoromethyl)-1 H-tetrazol-1-yl)-phenyl) methyl)-2-phenyl-3-piperidinamine dihydrochloride]) administered intramuscularly (1–10 mg/kg) reduced significantly the number of emetic response to cisplatin: this reduction was 60–81% ( P<0.05) for early emesis and 48–64% ( P<0.05) for the delayed response. Intracerebroventricularly administered GR205171 (30 μg/kg) also reduced the number of emetic responses: 53% ( P<0.05) in early emesis and 88% ( P<0.05) in the delayed response. However, the latency time to the first emesis was not affected by GR205171. Direct injection of cisplatin (10 μg/kg) into the fourth ventricle produced emesis, which was reduced by GR205171 administered via the peripheral or central route. Substance P-immunoreactive fibres were distributed throughout the dorsal vagal complex. These results suggest that the antiemetic effect of GR205171 on both emetic responses to cisplatin acts on a central site, and that the onset of the emetic response may be mediated partly via GR205171-insensitive mechanisms.

Three-Dimensional Mapping of Sensory Innervation with Substance P in Porcine Bronchial Mucosa

In asthma, neurogenic inflammation in bronchial airways may occur though the release of neuropeptides from C fibers via an axon reflex. Structural evidence for this neural pathway was sought in the pig and in humans by three-dimensional mapping of substance P-immunoreactive (SP-IR) nerves in whole mounts of mucosa using immunofluorescent staining and confocal microscopy. To show continuity, nerves were traced with 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate from their epithelial endings through the mucosa. The pan-neuronal marker protein gene product 9.5 revealed an extensive apical and basal plexus of nerves in the epithelium; 94% of these were varicose SP-IR fibers. Apical SP-IR fibers had a length density of 88 mm/mm(2). Varicose apical processes followed closely around the circumference of goblet cells. Calcitonin gene-related peptide was colocalized with SP-IR in varicosites. The epithelial fibers converged into bundles as they entered the lamina propria where lateral branches ran along arterioles, often contiguous with the vascular smooth muscle. 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate tracing showed that they projected to the epithelium. SP-IR fibers were rare near postcapillary venules. In human bronchial epithelium, protein gene product 9.5 revealed a similar apical and basal plexus of varicose fibers that weakly stained for SP-IR. Thus, a continuous sensory nerve pathway from the epithelium to arterioles provides structural support for a local axon reflex.