VIP modulates substance P-induced plasma extravasation in vivo

The selective PAC1 receptor agonist maxadilan inhibits neurogenic vasodilation and edema formation in the mouse skin

We have earlier shown that PACAP-38 decreases neurogenic inflammation. However, there were no data on its receptorial mechanism and the involvement of its PAC1 and VPAC1/2 receptors (PAC1R, VPAC1/2R) in this inhibitory effect. Neurogenic inflammation in the mouse ear was induced by topical application of the Transient Receptor Potential Ankyrin 1 (TRPA1) receptor activator mustard oil (MO). Consequent neurogenic edema, vasodilation and plasma leakage were assessed by measuring ear thickness with engineer's micrometer, detecting tissue perfusion by laser Doppler scanning and Evans blue or indocyanine green extravasation by intravital videomicroscopy or fluorescence imaging, respectively. Myeloperoxidase activity, an indicator of neutrophil infiltration, was measured from the ear homogenates with spectrophotometry. The selective PAC1R agonist maxadilan, the VPAC1/2R agonist vasoactive intestinal polypeptide (VIP) or the vehicle were administered i.p. 15 min before MO. Substance P (SP) concentration of the ear was assessed by radioimmunoassay. Maxadilan significantly diminished MO-induced neurogenic edema, increase of vascular permeability and vasodilation. These inhibitory effects of maxadilan may be partially due to the decreased substance P (SP) levels. In contrast, inhibitory effect of VIP on ear swelling was moderate, without any effect on MO-induced plasma leakage or SP release, however, activation of VPAC1/2R inhibited the increased microcirculation caused by the early arteriolar vasodilation. Neither the PAC1R, nor the VPAC1/2R agonist influenced the MO-evoked increase in tissue myeloperoxidase activity. These results clearly show that PAC1R activation inhibits acute neurogenic arterial vasodilation and plasma protein leakage from the venules, while VPAC1/2R stimulation is only involved in the attenuation of vasodilation.

Neural mechanisms of pelvic organ cross-sensitization

Clinical observations of viscerovisceral referred pain in patients with gastrointestinal and genitourinary disorders suggest an overlap of neurohumoral mechanisms underlying both bowel and urinary bladder dysfunctions. Close proximity of visceral organs within the abdominal cavity complicates identification of the exact source of chronic pelvic pain, where it originates, and how it relocates with time. Cross-sensitization among pelvic structures may contribute to chronic pelvic pain of unknown etiology and involves convergent neural pathways of noxious stimulus transmission from two or more organs. Convergence of sensory information from discrete pelvic structures occurs at different levels of nervous system hierarchy including dorsal root ganglia, the spinal cord and the brain. The cell bodies of sensory neurons projecting to the colon, urinary bladder and male/female reproductive organs express a wide range of membrane receptors and synthesize many neurotransmitters and regulatory peptides. These substances are released from nerve terminals following enhanced neuronal excitability and may lead to the occurrence of neurogenic inflammation in the pelvis. Multiple factors including inflammation, nerve injury, ischemia, peripheral hyperalgesia, metabolic disorders and other pathological conditions dramatically alter the function of directly affected pelvic structures as well as organs located next to a damaged domain. Defining precise mechanisms of viscerovisceral cross-sensitization would have implications for the development of effective pharmacological therapies for the treatment of functional disorders with chronic pelvic pain such as irritable bowel syndrome and painful bladder syndrome. The complexity of overlapping neural pathways and possible mechanisms underlying pelvic organ crosstalk are analyzed in this review at both systemic and cellular levels.

Applied information retrieval and multidisciplinary research: new mechanistic hypotheses in complex regional pain syndrome

Background

Collaborative efforts of physicians and basic scientists are often necessary in the investigation of complex disorders. Difficulties can arise, however, when large amounts of information need to reviewed. Advanced information retrieval can be beneficial in combining and reviewing data obtained from the various scientific fields. In this paper, a team of investigators with varying backgrounds has applied advanced information retrieval methods, in the form of text mining and entity relationship tools, to review the current literature, with the intention to generate new insights into the molecular mechanisms underlying a complex disorder. As an example of such a disorder the Complex Regional Pain Syndrome (CRPS) was chosen. CRPS is a painful and debilitating syndrome with a complex etiology that is still unraveled for a considerable part, resulting in suboptimal diagnosis and treatment.

Results

A text mining based approach combined with a simple network analysis identified Nuclear Factor kappa B (NFκB) as a possible central mediator in both the initiation and progression of CRPS.

Conclusion

The result shows the added value of a multidisciplinary approach combined with information retrieval in hypothesis discovery in biomedical research. The new hypothesis, which was derived in silico, provides a framework for further mechanistic studies into the underlying molecular mechanisms of CRPS and requires evaluation in clinical and epidemiological studies.

Modulation of peripheral inflammation by the substance P N-terminal metabolite substance P1-7

The N-terminal metabolite of the undecapeptide substance P (SP), substance P1-7 (SP1-7), is known to modulate nociception in the central nervous system (CNS) and often has opposite effects from SP. This study investigated the ability of SP(1-7) to modulate the vasodilatation response to SP in anaesthetized rats under different injury conditions using a blister model of inflammation on the hind footpad. The results indicated that SP1-7 inhibited the vascular response to SP in a dose-dependent manner. The putative antagonists naloxone and D-Pro2-D-Phe7-SP1-7 (D-SP1-7) reversed the effect of SP1-7. D-SP1-7 improved the responsiveness to SP under chronic nerve injury, which suggests a role for endogenous SP1-7 in this model. SP1-7 did not inhibit the response to electrical stimulation of the sciatic nerve, which indicates that the heptapeptide interacts at a post-terminal binding site. The current results suggest that SP1-7 may have inhibitory properties in inflammation, analogous to its antinociceptive role in the central nervous system.

Early and Late Effects of Capsaicin Pretreatment in Otitis Media with Effusion

PURPOSE

Discovery of the role of the neurogenic inflammation in the formation of otitis media with effusion has led to the investigation of the place of some neuropeptide antagonists in the treatment. In the current study, we investigated the effect of capsaicin (CP) pretreatment on the inflammation and proliferation in the middle ear mucosa and on the nerve fibers containing substance P, vasoactive intestinal polypeptide, and calcitonin gene-related peptide.

METHODS

Seventeen Wistar rats were used in the study. Ten rats were given CP on 3 consecutive days, and seven rats were given isotonic saline solution. Seven days after the third injection, animals were operated on, and their eustachian tubes were occluded. On the seventh day after the operation, five rats from the test group and three from the control group were killed. The others were killed 21 days after the operation. In the histopathologic examination of the sections, acute inflammation and proliferation scores were determined. Gland degeneration, goblet cell hyperplasia, and the density of mast cells were evaluated. Neural elements were stained immunohistochemically.

RESULTS

The acute inflammation score in the test group was lower, but the difference was insignificant (p > 0.05). The proliferation score in the test group was lower, and the difference was significant (p = 0.02). In the control group, gland degeneration was significantly higher (p = 0.044). Goblet cell hyperplasia demonstrated no difference between two groups (p > 0.05). Mast cell density was higher in the control group, but the difference was not significant (p > 0.05). Substance P immunoreactivity (IR) was significantly higher in the control group (p = 0.015). calcitonin gene-related peptide-IR and vasoactive intestinal polypeptide-IR were limited in both groups.

CONCLUSIONS

That CP pretreatment reduces inflammatory proliferative findings, and gland degeneration leads us to consider that it could be effective in both treatment of experimental otitis media with effusion and prevention of its complications.

Role of vasoactive intestinal polypeptide in burn-induced oedema formation

Vasoactive intestinal polypeptide has been demonstrated to lack inherent effects on capillary permeability, but also to potentiate the oedema promoting actions of other inflammatory mediators or even to strongly reduce organ damage and subsequent oedema in ischemic models of the lung and heart. This study investigated the role of VIP on oedema in partial- and full-thickness skin burns of anaesthetised rats in vivo by spectrophotometrical quantification of Evans blue albumin. Results show that systemic VIP elicited a significant drop in mean arterial blood pressure versus saline (p<0. 001) and VIP antiserum (p<0.001) both in burned and non-burned animals. VIP also decreased heart rate versus saline (p<0.05) and anti-VIP (p<0.01) in non-burned and burned animals. EB-albumin in normal skin was significantly inhibited by VIP as compared to saline (p<0.05), but did not differ significantly from VIP-antiserum. A significant inhibition of EB-albumin extravasation versus saline was also seen following administration of VIP-antiserum (p<0.01). Similarly, VIP significantly reduced EB-albumin extravasation versus saline treatment in partial-thickness (p<0.01) and full-thickness burns (p<0.001), while VIP-antiserum had no significant effect on skin perfusion in any of the burned groups as compared to saline treatment. The present results show that systemic VIP is a potent inhibitor of burn oedema. This effect could be secondary to constriction of skin vessels as a result of VIP-induced systemic hypotension or be mediated by the interaction of VIP with other oedema promoting mediators released following a thermal trauma to the skin.

Vasoactive intestinal polypeptide induces analgesia and impairs the antinociceptive effect of morphine in mice

Vasoactive intestinal polypeptide (VIP) has numerous regulatory roles in peripheral, endocrine organs and in the central nervous system. The present study related to the effects of centrally (intracerebroventricularly) administered VIP on pain sensitivity and on opiate tolerance and dependence in intact male CFLP mice. VIP was analgesic when administered alone centrally. Naloxone treatment abolished this analgesic effect. VIP decreased the analgesic effect of a single subcutaneous morphine injection and the development of chronic tolerance to morphine. Morphine withdrawal signs were not significantly affected after VIP pretreatment. These findings indicate that VIP may play a role in pain sensitivity and that an opiate component may participate in this effect.

CGRP and nitric oxide of neuronal origin and their involvement in neurogenic vasodilatation in rat skin microvasculature

1. Sensory nerves are important for the initiation of neurogenic inflammation and tissue repair. Both calcitonin gene-related peptide (CGRP) and nitric oxide (NO) have been implicated in neurogenic vasodilatation and inflammatory responses. 2. A blister model in the rat hind footpad was used as a site to induce neurogenic vasodilatation in response to antidromic electrical stimulation of the sciatic nerve. Blood flux was monitored with a laser Doppler flow monitor. 3. The quantitative contributions of CGRP and NO to vasodilatation were examined by use of the CGRP receptor antagonist CGRP8-37 and NO synthase inhibitors 7-nitroindazole (7-NI), 3-bromo 7-NI and N(G)-nitro L-arginine methyl ester (L-NAME). The potential modulatory role of endothelin was examined by use of the ET(A) receptor antagonist BQ-123. 4. CGRP8-37 (10 microM) was perfused over the blister base before nerve stimulation and continuously throughout the post-stimulation period, resulting in a significant reduction (41%) in the blood flux vascular response. 5. Pretreatment with the specific neuronal NO synthase inhibitors, 7-NI and 3-bromo 7-NI (10 mg kg(-1), i.v.), and of the non-specific L-NAME (100 microM), resulted in significant inhibition of the blood flux response (36%, 72% and 57% decrease, respectively). In contrast, 7-NI treatment in young rats pretreated with capsaicin had no further effect on the vascular response, suggesting that the source of NO is the sensory nerves. 6. BQ-123 (10 microM) significantly enhanced the stimulation-induced blood flux response (61% increase). When 7-NI was co-administered with either CGRP8-37 or BQ-123, the drug actions were additive, suggesting that there was no interaction between NO and CGRP or endothelin. 7. These data suggest that both NO and CGRP participate in neurogenic vasodilatation in rat skin microvasculature and that this response is modulated by endogenous endothelin.

Effects of anti-allergic drugs on substance P (SP) and vasoactive intestinal peptide (VIP) in nasal secretions

To clarify the effects of anti-allergic drugs on substance P (SP) and vasoactive intestinal peptide (VIP) levels in nasal secretions, we employed competitive enzyme-linked immunoassays to measure concentrations of those neuropeptides in nasal secretions from 40 patients with house dust nasal allergy before and after administration of azelastine and oxatomide. One mg of azelastine and 30 mg of oxatomide were administrated twice a day for 4 weeks. Mean values of SP concentrations and ratios of SP to total protein of the nasal allergy group were significantly higher than those of the control group (p < 0.002). The VIP/total protein ratio of the allergy group was also significantly higher than that of the control group, although the VIP concentration alone was not. Mean levels of SP and VIP from patients with severe symptoms were significantly higher than those of the control group (p < 0.05), although those values were not significantly different between patients with moderate symptoms and control subjects. Azelastine and oxatomide effectively reduced SP levels in nasal secretions (p < 0.005), but they did not significantly decrease VIP levels. The reduction of SP levels was significant in patients with excellent responses to those drugs (p < 0.005), but not in patients with poor responses. These findings suggest that SP and VIP levels in nasal secretions may reflect the clinical state of nasal allergy and be one of the better parameters available for evaluating the clinical efficacy of anti-allergic drugs against nasal allergy.

N-(2-hydroxyethyl)hexadecanamide is orally active in reducing edema formation and inflammatory hyperalgesia by down-modulating mast cell activation

Mast cells play a key role in inflammatory reactions triggered by tissue injury or immune perturbations. Little is known about endogenous molecules and mechanisms capable of modulating inappropriate mast cell activity. N-(2-Hydroxyethyl)hexadecanamide (palmitoylethanolamide), found in peripheral tissues, has been proposed to act as a local autacoid capable of negatively regulating mast cell activation and inflammation-hence the acronym Autacoid Local Inflammation Antagonism (ALIA). Recently, N-(2-hydroxyethyl)hexadecanamide (LG 2110/1) has been reported to down-modulate mast cell activation in vitro by behaving as an agonist at the peripheral cannabinoid CB2 receptor. Here, we have characterized and functionally correlated the anti-inflammatory actions of LG 2110/1 with its ability to control mast cell activation, when given orally in a battery of rodent models of inflammation. LG 2110/1 diminished, in a dose-dependent and correllated manner, the number of degranulated mast cells and plasma extravasation induced by substance P injection in the mouse ear pinna. In addition, LG 2110/1 reduced dose dependently plasma extravasation induced by passive cutaneous anaphylaxis reaction. In adult rats LG 2110/1 decreased, in a dose-dependent manner, carrageenan-induced hindpaw edema and hyperalgesia, but not phospholipase A2-induced hindpaw edema. Further, anti-edema effects were observed when utilizing dextran and formalin, known to also cause mast cell activation. Locally administered LG 2110/1 was likewise effective in minimizing dextran-induced hind paw edema. In contrast, equivalent amounts of palmitic acid plus ethanolamine were ineffective against plasma extravasation provoked by substance P. LG 2110/1 did not decrease plasma extravasation induced by the substance P fragment, substance P-(6-11), known to be inactive on mast cells. These results indicate that orally administered N-(2-hydroxyethyl)hexadecanamide is effective in: (a) directly down-modulating mast cell activation in vivo; (b) suppressing pathological consequences initiated by mast cell activation independently of the activating stimuli; (c) exerting an anti-inflammatory action distinguishable from that of classical steroidal and non-steroidal anti-inflammatory agents. These findings raise the possibility that N-(2-hydroxyethyl)hexadecanamide and related saturated N-acylamides ('ALIAmides') represent novel therapeutic agents useful in the management of inflammatory disease conditions.

Mechanisms of increased airway microvascular permeability: role in airway inflammation and obstruction

1. Airway inflammation is a signal feature of human asthma, as is bronchial obstruction and the resultant airflow limitation. An obligatory accompaniment to airway inflammation is increased airway microvascular permeability, which in turn is causally related to bronchial oedema. In this review, we have attempted to describe the mechanisms of increased airway microvascular permeability and its relationship to oedema, bronchial obstruction and the hyperreactivity to spasmogenic stimuli which are such common features of asthma. 2. It is now clear that bronchial obstruction in chronic asthma can involve bronchial wall oedema and swelling in addition to reversible, elevated airway smooth muscle tone, mucus hypersecretion and airway plugging and potentially permanent structural changes in airway architecture. Inflammatory mediators released in the airway wall in asthma including histamine, platelet-activating factor, leukotrienes and bradykinin are potent inducers of increased bronchial microvascular permeability and are thus promoters of bronchial oedema, airway wall swelling and reduction in luminal calibre. 3. The primary mechanism believed to underlie acute increases in microvascular permeability is contraction of post-capillary venular endothelial cells, resulting in the formation of gaps between otherwise tightly associated cells. Extravasated plasma distributes to the interstitial spaces in the airway wall, resulting in oedema and swelling, but may also traverse the epithelium and collect in the airway lumen. 4. Luminal plasma may compromise epithelial integrity and cilial function and thus reduce mucus clearance. Plasma proteins may also promote the production of viscous mucus and the formation of luminal mucus plugs. Together, these effects can result in or contribute to airway obstruction and hyper-responsiveness. 5. An understanding of such mechanisms can provide insight concerning novel and effective anti-asthma therapies.

Role of vasoactive intestinal peptide (VIP) in pathogenesis of ethanol-induced gastric mucosal damage in rats

To elucidate the possible role of vasoactive intestinal peptide (VIP) in the pathogenesis of acute gastric mucosal damage, rats were treated intragastrically with 1.0 ml 96% ethanol with or without intravenous or intraperitoneal coadministration of VIP (1 nmol/liter to 1 mumol/liter/100 g). VIP was found to double the mean lesion area when compared with that induced by ethanol alone (P < 0.05), an effect that was prevented by VIP antagonist (1 mumol/liter/100 g). A substance P antagonist (1 mumol/liter/100 g) also reduced the extent of gastric damage induced by coadministration of VIP and ethanol. VIP antagonist or substance P antagonist significantly reduced ethanol-induced gastric mucosal damage. Gastric mucosal levels of LTB4, LTC4, VIP, and substance P were significantly increased in ethanol-treated rats as compared with saline-treated animals (P < 0.05). The augmentation of ethanol-induced damage by VIP was associated with increased gastric mucosal levels of LTB4. In VIP-treated rats, gastric mucosal levels of substance P were found to be significantly increased compared with control rats (P < 0.05). Administration of VIP to pyloric-ligated rats significantly increased gastric acid output and blood pepsinogen A levels as compared with saline treated rats (P < 0.05). Ketotifen, a mast cell stabilizer (100 micrograms/100 g), administered orally 30 min before damage induction by ethanol, with or without VIP, totally abolished the damage of the surface epithelium of the entire gastric mucosa and significantly reduced the mucosal levels of LTC4 and LTB4 (P < 0.05). It is suggested that VIP is involved in the pathogenesis of acute ethanol-induced gastric mucosal damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Skin vascular reactivity to the neuropeptide substance P in rats with peripheral mononeuropathy

A compression neuropathy model that produces pain-related behaviour in rats was used to investigate changes in skin vascular reactivity in the innervated area. Neuropathy was produced by 4 ligatures tied loosely around the common sciatic nerve. Vascular reactivity was assessed via perfusion of the neuropeptide substance P (SP) over the base of a blister raised on the rat foot pad. Compared to sham-operated rats, experimental rats exhibited a decrease in their vasodilatation response to SP 2-5 weeks after ligatures were tied. A bilateral decrease in vasodilatation to sodium nitroprusside perfusion in treated rats suggested part of the altered SP response was due to diminished vascular reactivity. Plasma extravasation in response to SP was also decreased on the operated side of ligatured rats, significant 4 and 6 weeks after the operation. The results support studies that suggest neurogenic inflammation is altered in chronic neuropathic pain states.

Substance P and vasoactive intestinal peptide in nasal secretions and plasma from patients with nasal allergy

To clarify the role of substance P (SP) and vasoactive intestinal peptide (VIP) in nasal allergy, we measured their concentrations in the nasal secretions and plasma of normal subjects and patients with nasal allergy to house dust and Japanese cedar pollen by competitive enzyme-linked immunoassay. The mean levels of SP (224 pmol/L) and VIP (41.6 pmol/L) in the nasal secretions of normal subjects were significantly higher than those in plasma (SP 3.04 pmol/L and VIP 1.04 pmol/L; p < .01). The mean levels of SP and VIP in the nasal secretions of the pollinosis group were significantly higher than those of the control group (p < .05 and p < .01), while the levels of the house dust allergy group were not higher than those of the control group. Intranasal allergen challenge significantly reduced SP levels in the nasal secretions of the allergy groups, while it did not influence VIP levels in the nasal secretions. These findings suggest that SP and VIP are actively secreted into the nose and may play an important role in the allergic reaction on the surface of the human nasal mucosa.

Increased expression of preprotachykinin, calcitonin gene-related peptide, but not vasoactive intestinal peptide messenger RNA in dorsal root ganglia during the development of adjuvant monoarthritis in the rat

Neuropeptides in dorsal root ganglia (DRG) have been implicated in the pathogenesis of pain and neurogenic inflammation in experimental and clinical arthritis. Recently we demonstrated increased levels of substance P (SP) and calcitonin gene-related peptide (CGRP) confined to innervating DRG in adjuvant-mediated monoarthritis. We have now investigated whether changes in peptide content are reflected in altered neuropeptide gene expression and the time course involved. Using in situ hybridization we found marked increases in expression of beta-preprotachykinin (PPT; 81 +/- 24% rise) and alpha-CGRP (44 +/- 6% rise) mRNAs in innervating (ipsilateral L5) DRG neurones only. These increases occurred at the onset of acute inflammation (8 h) and persisted until chronic arthritis developed after 14 days. There were no changes in the proportion of DRG neurones expressing PPT or CGRP mRNAs. Messenger RNA encoding vasoactive intestinal polypeptide (VIP) was not induced. These data suggest that increased synthesis of PPT and CGRP peptides in DRG may play a role in the pathogenesis both of adjuvant-mediated acute inflammation and chronic arthritis.

Anatomical basis for a parasympathetic and sensory innervation of the intracranial segment of the internal carotid artery in man. Possible implication for vascular headache

Two ganglionic cell groups, located close together and called the internal carotid ganglion, not described before in man, were demonstrated extradurally on the ventrolateral surface of the human internal carotid artery (ICA), where the greater superficial petrosal nerve is joined by the (greater) deep petrosal nerve to form the vidian nerve. The two ganglionic cell groups have fiber connections to the ICA, and consist of 50-70 cells each. By immunohistochemistry the majority of cells in one of the groups were shown to contain vasoactive intestinal polypeptide (VIP) and choline acetyltransferase (ChAT) indicating a parasympathetic function, whereas most cells in the other group contained substance P (SP) and possibly calcitonin gene-related peptide (CGRP), transmitters in pain fibers. Lateral to the intracavernous segment of ICA 10-150 scattered or aggregated VIP- and ChAT-positive cells were found, with fiber connections to the ophthalmic nerve, the ICA, the abducent nerve and the sphenopalatine ganglion. These cells may represent aberrant parasympathetic (sphenopalatine) ganglia, here referred to as cavernous ganglion. By radioimmunoassay substantial amounts of VIP, SP and CGRP were measured in both the extradural and the intracavernous segment of the ICA. Thus, the intracranial segment of the ICA is most likely innervated by parasympathetic and pain fibers from the internal carotid ganglion, sensory fibers from the ophthalmic division of the trigeminal ganglion, and parasympathetic fibers from the sphenopalatine and/or cavernous ganglion. Clinical implications for the activation of these nerves to cause pain, dilatation and edema in this segment of the ICA during attacks of cluster headache and painful ophthalmoplegic syndromes are discussed.

Vasoactive intestinal polypeptide (VIP) potentiates the behavioral effect of substance P intrathecal administration

Intrathecal (IT) injection of 20 micrograms substance P (SP) induced a behavioral syndrome consisting of scratching and biting the flanks (83% and 57%, respectively, of 48 rats), and distress-like vocalization (42% of 26 rats tested) in response to a previously innocuous tactile stimulus with a von Frey fiber (allodynia). These behavioral events following SP were of short latency (1-2 min) and duration (around 10 min). Injection IT of 5 micrograms, but not 1 microgram, of vasoactive intestinal polypeptide (VIP), concurrently with SP, significantly increased the frequency of both scratching and biting bouts over that produced by SP alone. VIP IT alone (1 or 5 micrograms) did not stimulate scratching-biting, but induced allodynia in a significant proportion of rats.

Pathways of parasympathetic and sensory cerebrovascular nerves in monkeys

Using immunohistochemistry, we studied the origins and pathways of parasympathetic and sensory nerve fibers to the pial arteries in four squirrel monkeys. Following its application to the surface of the middle cerebral artery, the retrograde axonal tracer True Blue accumulated in parasympathetic neurons of the sphenopalatine ganglion and the internal carotid ganglion. The latter is strategically located where the internal carotid artery enters the cranium. Fibers from the sphenopalatine ganglion reach the internal carotid artery in the cavernous sinus region after running as rami orbitales. Before reaching the internal carotid artery, the fibers bypass aberrant sphenopalatine ganglia, with the most distant, the cavernous ganglion, being located in the cavernous sinus region. True Blue also accumulated in sensory neurons of the ophthalmic and maxillary divisions of the trigeminal ganglion and in sensory neurons of the internal carotid ganglion. Fibers from the ophthalmic division of the trigeminal ganglion reach the internal carotid artery as a branch through the cavernous sinus, bypassing the cavernous ganglion. Fibers from the maxillary division also bypass the cavernous ganglion after reaching it via a recurrent branch of the orbitociliary nerve. Thus, the cavernous ganglion forms a confluence zone for parasympathetic and sensory fibers in the region. In addition, parasympathetic and sensory fibers leave the confluence zone to follow the abducent and trochlear nerves backward to the basilar artery and tentorium cerebelli, respectively. Clinical implications are discussed.

Neural control of human nasal secretion

Patients with allergic and non-allergic nasal disorders may complain of symptoms of itching, discharge, congestion or fullness, and obstruction of airflow. The actions of sensory nerves and parasympathetic reflexes are central to the development of these symptoms, and likely play crucial roles in allergic and non-allergic nasal pathology. Nasal provocation studies have provided much information about the nature of the processes which contribute to the production of nasal secretions and the development of obstruction to nasal air flow. The results of human nasal provocation studies will be discussed after a review of the special anatomy of the human nasal mucosa, its vasculature, and its innervation.

Serotonin modulates substance P-induced plasma extravasation and vasodilatation in rat skin by an action through capsaicin-sensitive primary afferent nerves

Using a blister model of inflammation in the rat hind footpad, the present study was undertaken to examine the ability of serotonin (5-HT) to modulate an inflammatory reaction manifested as plasma extravasation and vasodilatation induced by the neuropeptide substance P (SP). In addition, the role of primary afferent sensory nerve fibres in these modulatory effects was studied in capsaicin pretreated rats. Using a protocol of simultaneous perfusion of amine and peptide over the blister base, no major modulatory effect was observed. On the other hand, using a protocol of sequential perfusion, 5-HT was found to extend the plasma extravasation and vasodilatation responses to SP. 5-HT maintained the plasma extravasation response to SP after cessation of stimulation (during the post-stimulation period). On the other hand, it extended the vasodilatation response to SP during the actual stimulation period by preventing the occurrence of tachyphylaxis. These modulatory effects were absent in capsacin-pretreated rats. The present study provides evidence for the first time in vivo to suggest that serotonin can modulate an inflammatory response to SP via a mechanism that involves capsaicin-sensitive sensory fibres.

Vasoactive intestinal peptide in human nasal mucosa

Vasoactive intestinal peptide (VIP), which is present with acetylcholine in parasympathetic nerve fibers, may have important regulatory functions in mucous membranes. The potential roles for VIP in human nasal mucosa were studied using an integrated approach. The VIP content of human nasal mucosa was determined to be 2.84 +/- 0.47 pmol/g wet weight (n = 8) by RIA. VIP-immunoreactive nerve fibers were found to be most concentrated in submucosal glands adjacent to serous and mucous cells. 125I-VIP binding sites were located on submucosal glands, epithelial cells, and arterioles. In short-term explant culture, VIP stimulated lactoferrin release from serous cells but did not stimulate [3H]glucosamine-labeled respiratory glycoconjugate secretion. Methacholine was more potent than VIP, and methacholine stimulated both lactoferrin and respiratory glycoconjugate release. The addition of VIP plus methacholine to explants resulted in additive increases in lactoferrin release. Based upon the autoradiographic distribution of 125I-VIP binding sites and the effects on explants, VIP derived from parasympathetic nerve fibers may function in the regulation of serous cell secretion in human nasal mucosa. VIP may also participate in the regulation of vasomotor tone.

Gastrin-releasing peptide in human nasal mucosa

Gastrin-releasing peptide (GRP), the 27 amino acid mammalian form of bombesin, was studied in human inferior turbinate nasal mucosa. The GRP content of the mucosa measured by radioimmunoassay was 0.60 +/- 0.25 pmol/g tissue (n = 9 patients; mean +/- SEM). GRP-immunoreactive nerves detected by the immunogold method of indirect immunohistochemistry were found predominantly in small muscular arteries, arterioles, venous sinusoids, and between submucosal gland acini. 125I-GRP binding sites determined by autoradiography were exclusively and specifically localized to nasal epithelium and submucosal glands. There was no binding to vessels. The effects of GRP on submucosal gland product release were studied in short-term explant culture. GRP (10 microM) significantly stimulated the release of the serous cell-specific product lactoferrin, and [3H]glucosamine-labeled glycoconjugates which are products of epithelial goblet cells and submucosal gland cells. These observations indicate that GRP released from nerve fibers probably acts on glandular GRP receptors to induce glycoconjugate release from submucosal glands and epithelium and lactoferrin release from serous cells, but that GRP would probably not affect vascular permeability.

Substance P increases rat aortic albumin permeability

We tested the hypothesis that exogenous substance P (SP) could enhance rat aortic permeability to plasma albumin. Fluorescein-labeled bovine serum albumin was used as the tracer. In vivo normalized albumin mass transfer rates (x10(-8) cm/sec) were 9.16 +/- 1.73, 14.20 +/- 2.76 (P less than 0.05) and 20.31 +/- 3.31 (P less than 0.001) for groups infused i.v. with 0.01 N acetic acid vehicle, 7.4 pmol and 0.74 pmol SP/kg/min for 5 min, respectively. No significant differences from the control group were found in rats receiving 150 pmol, 74 pmol nor 74 fmol SP/kg/min for 5 min. The results indicate that aortic permeability dynamics for plasma albumin can be enhanced by pmol levels of the tachykinin SP.

Substance P-induced cutaneous plasma extravasation in rats is mediated by NK-1 tachykinin receptors

Substance P (SP), a relatively non-selective tachykinin receptor agonist, and Septide and Senktide, highly selective NK-1 and NK-3 tachykinin receptor agonists, respectively, were injected intradermally in rats. The resulting cutaneous plasma extravasation (PE) was evaluated by measuring the amount of Evans blue that leached from the circulation into the skin. SP and Septide produced dose dependent PE, Septide being the more potent of the two. Senktide did not produce PE, even at doses 10,000 times higher. Neonatal capsaicin treatment significantly reduced SP- and Septide-induced PE. These data indicate that SP-induced PE is mediated by NK-1 tachykinin receptors.

Tachykinin-induced vasodilatation in rat skin measured with a laser-Doppler flowmeter: evidence for receptor-mediated effects

Vasodilatation was induced by perfusion of the tachykinins substance P (SP), neurokinin A and neurokinin B and the analogues [Glp6, D-Pro9]SP-(6-11) and [Glp6, L-Pro9]SP-(6-11) over the base of vacuum-induced blisters on the rat footpad. Vasodilatation was measured as change in blood flow using a laser-Doppler flowmeter. The tachykinins induced vasodilatation in a dose-response manner with a threshold of approximately 3 pmol and pD2's of 6.48, 6.13 and 6.21 for SP, neurokinin A and neurokinin B respectively. The D- and L-Pro analogues of [Glp6, Pro9]SP-(6-11) also induced vasodilatation in a dose-dependent manner. The L-Pro analogue was more potent than the D-Pro analogue (D/L ratio of the EC50's = 21) which suggests the involvement of an NK-1 type receptor in the mediation of small vessel vasodilatation. The vasodilatation to SP was reduced by 64% and 59% in capsaicin- and antihistamine-pretreated animals respectively, demonstrating the involvement of capsaicin-sensitive primary afferent nerves and mast cells in the vasodilatation component of the neurogenic inflammatory response.