Substance P in the human brain

The distribution of substance P immunoreactive sites was investigated by immunoenzymatic methods in a large series of paraffin embedded human brain sections from the collection assembled by Oscar and Cécile Vogt several decades ago, as well as from more recent post-mortem material. These studies demonstrated that substance P immunoreactivity was preserved in archival material permitting a detailed account of the localization of immunoreactive cell bodies, fibre networks and tracts in the human brain. Previous observations made on experimental animals and man were confirmed and extended. Additionally, substance P immunoreactive cell bodies were seen in most cortical areas and novel features were noted in the distribution of substance P-containing elements in the tuberal region, corpus striatum, substantia nigra (particularly in relationship to blood vessels) and in association with melanin-containing cells. Reconstruction of some substance P pathways was attempted by the analysis of semi-serial sections in more than one plane. Immunocytochemistry, in combination with image analysis, enabled some measurements of the differential concentrations of substance P immunoreactive material to be made and allowed a close correlation of this with defined anatomical landmarks or enkephalin immunoreactive sites.     

Substance P and opiate-like peptides in human adrenal medulla

Opiate-like peptides (OLP), substance P (SP) and catecholamines (CA) were measured in 15 human adrenal medullae. Two groups of subjects were investigated. Group a consisted of subjects who died after traffic accidents and Group b consisted of subjects with other causes of death. OLP levels in Group a were only about 13%, and SP and CA levels about 50% of Group b. It is suggested that these differences might be due to massive premortal adrenal medullary discharge rather than post mortem degradation.     

Substance P and neurokinin A in human nasal mucosa.

The tachykinins substance P (SP) and neurokinin A (NKA) were studied in human inferior turbinate nasal mucosa by radioimmunoassay, immunohistochemistry, and autoradiography and for their effect upon mucus release in an in vitro culture system in order to infer their potential functions in the upper respiratory tract. Similar amounts of SP (1.03 +/- 0.12 pmol/g wet weight; mean +/- SEM; n = 26) and NKA (0.76 +/- 0.23; n = 7) were found. NKA and SP immunoreactive nerve fibers were found in the walls of arterioles, venules, and sinusoids and as individual fibers in gland acini, near the basement membrane, and in the epithelium. [125I]SP bound to arterioles, venules, and glands. [125I]NKA bound only to arterioles. In short-term explant culture of fragments of human nasal mucosa, both 1 microM SP and 1 microM NKA stimulated release of [3H]glucosamine-labeled respiratory glycoconjugates. These results indicate that SP and NKA have similar distributions in nociceptive sensory nerves in human nasal mucosa. The distribution of [125I]SP binding sites is consistent with a role for SP as a vasodilator and mucous secretagogue. The presence of [125I] NKA binding sites on vessels suggests a primary role for NKA in regulating vasomotor tone.     

浅述P物质与胰腺疾病

P物质是一种脑肠肽，它广泛地分布在中枢神经系统和外周组织器官，在不同的部位发挥不同的生物学效应。在中枢它作为神经递质发挥作用且与痛觉传导有关，在外周神经它作为诱导神经源炎症的物质发挥作用。近年来发现P物质与胰腺的疾病如胰腺炎、糖尿病和胰腺癌关系密切。     

Substance P induces histamine release from human pulmonary mast cells

Substance P elicits histamine release from human skin and rodent mast cells. Since neuropeptide-mediated reflexes may be important in asthma, we examined the ability of substance P to stimulate human mast cells obtained at bronchoalveolar lavage (BAL). BAL samples were obtained at routine bronchoscopy from 35 non-preselected patients. Histamine release experiments were performed in a standard manner using substance P and the calcium ionophore A23187. Both substance P (50 μM) and A23187 caused histamine release (median 26.7%, range 6.2–62.8% and 32.1%, 7.7–56.8% respectively) which was significantly greater (P < 0.0001) than the spontaneous release (median 15.6%, range 4.1–33.4%), i.e. that in the absence of any stimulus. Substance P induced histamine release was via an energy dependent process and was blocked by preincubation with antimycin A. A significant correlation was observed between substance P induced release and spontaneous release but was not observed with A23187 induced release. Mast cell counts correlated significantly with substance P induced release but not with spontaneous or A23187 induced release. The substance P induced histamine secretion was elicited at similar concentrations to those used with rodent and human skin mast cells. Asthma is associated with increased numbers of mast cells which have both increased spontaneous and stimulated secretory responses. Thus, in vivo, the bronchoconstrictor action of substance P may in part result from activation of mast cells in the bronchial lumen.     

Substance P concentrations in human cerebrospinal fluid vary inversely with age

The mean concentrations of immunoreactive substance P in cerebrospinal fluid (CSF) of 10 fetuses (gestational age 11-20 weeks) were 22.7 +/- 8.3 pmol/ml, compared with 250.0 +/- 28.2 fmol/ml in premature babies (gestational age 25-31.5 weeks, n = 8), 141.0 +/- 14.2 fmol/ml in full term newborn babies (n = 5), 50.0 +/- 2.3 fmol/ml in children (age 1-6 years, n = 6), and 9.5 +/- 1.5 fmol/ml in 5 adults. The differences between successive age groups were all statistically significant. The high concentration of substance P in human CSF in the early stages of development and its continuous decline towards maturity encourages the idea that substance P plays a role in neuro-development.     

Substance P and multiple sclerosis.

Multiple sclerosis is an inflammatory disease which affects the white matter of the central nervous system (CNS). The aetiology of this condition is unknown but it is generally believed to represent an autoimmunological response to a component of myelin triggered by an environmental factor, in a genetically susceptible individual. The natural history of the disease, in terms of clinical disability, is unpredictable, and the factors responsible unknown. Substance P is an undecapeptide that acts as a neurotransmitter in the CNS and as a regulator of immune responses. The recent discovery of substance P immunoreactive astrocytes in multiple sclerosis plaques raises the possibility that this peptide may be important both in the development of plaques and in governing the natural history of the disease.     

Substance P modulates lymphokine activities in supernatants of cultured human duodenal biopsies

A duodenal biopsy culture technique was used to investigate the effect of substance P on lymphokine secretion by the human gut associated lymphoid tissue. Duodenal biopsies of 7 healthy volunteers were cultured in 1 ml medium each with Pokeweed mitogen (1 microgram/ml) for 4 days at 37 degrees C. Substance P (SP) was added in concentrations ranging from 10(-12) M to 10(-6) M. Media were changed every day. Interleukin (IL)-1 beta, IL-2 and IL-2-receptor activities were determined by means of specific ELISAs. Values were referred to 5 mg biopsy weight and expressed as per cent change of basal Pokeweed mitogen-pulsed supernatant activities. 10(-8) M and 10(-6) M SP led to a decrease of IL-1 beta activity (78 +/- 13.9% and 62.8 +/- 17.1%, respectively, alpha = 0.01 each). In contrast, 10(-8) and 10(-10) M SP showed an increase in IL-2 activity up to 182.9 +/- 94.5% and 295.6 +/- 144.7%, respectively. 10(-6) M and 10(-8) M SP enhanced IL-2 receptor activities by 81.5 +/- 70% and 40.9 +/- 11.8%, respectively (alpha = 0.05). The present data demonstrate for the first time distinct SP-mediated effects on lymphokine activities in supernatants of cultured human duodenal biopsies.     

Substance P augments tumor necrosis factor release in human monocyte-derived macrophages.

Substance P (SP) is an undecapeptide that has the amino sequence Arg-Pro-Lys-Pro-Gin-Gln-Phe-Phe-Gly-Leu-Met-NH2 and that belongs to a family of structurally related peptides known as tachykinins, the latter are widely distributed in the central nervous system. SP is involved in the biological activities of cells in the immune system, including the induction of cytokines in immune cells. We have investigated the effects of SP on constitutive and/or lipopolysaccharide (LPS)-induced expression of tumor necrosis factor (TNF) in cultured blood monocyte-derived macrophages (MDM). Cells cultured in vitro for 14 days were treated with SP at various concentrations (10(-10) to 10(-6M) in the presence of LPS before culture supernatants were harvested. TNF bioactivity in culture supernatants was measured with L929 cell line MDM from 10 of 12 donors treated with a SP alone showed increased TNF production. SP and LPS also interacted in a synergistic fashion in upregulating TNF production in MDM from responders. The stimulatory effect of SP was inhibited by two SP antagonists, spantide ([D-Arg-1-D-Trp-7-D-Trp-7-D-Trp-9-leu-11]-SP) and CP-96,345 (a nonpeptide antagonist of the SP receptor). In addition, an anti SP polyclonal antibody blocked the SP effect on TNF production in cultured MDM, further indicating the specificity of these effects. These results demonstrate that SP is an important regulator of monokine production by human monocytes/macrophages.     

Substance P modulates colitis-associated fibrosis

Substance P (SP) and the neurokinin-1 receptor (NK-1R) are involved in the development of colitis and mucosal healing after colonic inflammation. We studied whether SP modulates colonic fibrosis by using a chronic model of trinitrobenzenesulfonic acid (TNBS)-induced colitis in wild-type (WT) and NK-1R-deficient (NK-1R KD) mice. We found increased mRNA expression levels of collagen, vimentin, and the fibrogenic factors transforming growth factor β1 and insulin-like growth factor 1 in the chronically inflamed colons of WT mice treated with repeated intracolonic TNBS administrations. Fibrosis in TNBS-treated mice was also evident immunohistochemically by collagen deposition in the colon. Treatment of TNBS-exposed WT mice with the NK-1R antagonist CJ-12255 reduced colonic inflammation, colonic fibrosis, fibroblast accumulation, and expression levels of the fibrogenic factors. NK-1R knockout mice chronically exposed to TNBS had similar colonic inflammation compared with WT, but reduced colonic fibrosis, fibroblast accumulation, and expression levels of fibrogenic factors. Immunohistochemical staining also showed co-localization of NK-1R with fibroblasts in inflamed colons of mice and in colonic mucosa of patients with Crohn's disease. Exposure of human colonic CCD-18Co fibroblasts to SP (10 nmol/L) increased cell migration. SP stimulated collagen synthesis in CCD-18Co fibroblasts in the presence of transforming growth factor β1 and insulin-like growth factor 1, and this effect was reduced by Akt inhibition. Thus, SP, via NK-1R, promotes intestinal fibrogenesis after chronic colitis by stimulating fibrotic responses in fibroblasts.     

Substance P and substance P receptors in bone and gingival tissues

Substance P (SP) is an important member of the tachykinin family of neuropeptides, which work as neurotransmitters or neuromodulators. Recent advances in the analysis of SP receptors, particularly the neurokinin-1 receptors (NK1-Rs) that have high affinity for SP, have demonstrated that they are distributed not only in the cells of the neuronal or immune systems but also in peripheral cells. Therefore, the effect of SP and its cellular receptors is not limited to the nervous or immune systems, but is more extensive than previously appreciated. SP-like immunoreactive (SP-LI) axons have been localized in both bone and gingival tissue, and SP receptors are widely distributed in osteoclasts, osteoblasts, and junctional epithelial cells, as well as in neutrophils and endothelial cells. The distribution of SP-LI axons and SP receptors suggests that SP may directly modulate bone metabolism and gingival tissue functions through SP receptors.     

Involvement of substance P as a mediator in capsaicin-induced mouse ear oedema

We examined the involvement of substance P (SP) in mouse ear oedema induced by topical application of capsaicin (250 µg/ear). Reapplication of capsaicin at 4h, 24h, and 48h after initial treatment did not induce a second oedema response. Oedema induced after the second application was significantly (p<0.01 orp<0.001) suppressed for up to 30 days but was observed when capsaicin was applied 40 days after initial treatment. Topical pretreatment of ears with capsaicin at 4h, 24h and 48h before i.v. injection of SP (5 µg/kg) did not cause a significant inhibition of plasma extravasation in ear skin. NK₁ receptor antagonists such as RP 67580 (ED₅₀:0.19 mg/kg, i.v.), spantide II (ED₅₀:0.33 mg/kg, i.v.), and GR 82334 (ED₅₀:0.26 mg/kg, i.v.), inhibited capsaicin-induced ear oedema, whereas SR 48968 (2.0 mg/kg, i.v.), a NK₂ receptor antagonist, had no effect. Furthermore, RP 67580 (0.5 kg/mg, i.v.) inhibited the oedema response induced by reapplication of capsaicin at 50 days after initial treatment. These results indicate that tachyphylaxis of capsaicin-induced oedema is reversible and suggest that this response may be due mainly to a reduction of SP in sensory neurones but not to any loss of responsiveness of NK₁ receptors. We also conclude that SP and NK₁ receptors are involved predominantly in the development of capsaicin-induced mouse ear oedema.     

Substance P primes the formation of hydrogen peroxide and nitric oxide in human neutrophils.

Substance P (SP), a neurotransmitter of the central and peripheral nervous system, has been implicated as a mediator of the pulmonary inflammatory response through its stimulatory effects on neutrophils. We investigated the role of SP in priming the production of reactive oxygen species by human neutrophils with the cytochrome c reduction assay and by flow cytometry using the intracellular oxidizable probe dichlorofluorescein. We also investigated SP-induced formation of nitrite and nitrate as an index of nitric oxide (NO) production. Our results indicate that SP primes two distinct pathways with respect to the induction of reactive oxygen species in the human neutrophil: the production of superoxide anion and hydrogen peroxide by the calmodulin-dependent NADPH oxidase, and the generation of NO by a constitutive NO synthase. Preincubation of neutrophils with inhibitors of calmodulin and NO synthase diminished the oxidative response in an additive fashion. These results give insight into distinct signal transduction pathways in the SP-primed neutrophil with respect to the formation of superoxide anion, hydrogen peroxide, and NO.     

Substance P and calcitonin gene-related peptide: effects on mast cells and in human skin

Mast cells are found in close association with blood vessels, and histamine is known to be a potent vasodilator in humans. It is now clear that mast cells form neuroeffector junctions and that one of the types of nerve involved is the peptide-containing primary afferent neurone (C fibre). Nerve stimulation produces vasodilation which is blocked by antihistamines or by depletion of mast cell histamine with compound 48/80. Nerve stimulation also releases histamine and degranulates mast cells. Substance P and other neuropeptides release histamine from isolated rat and human skin mast cells. The actions of substance P and calcitonin gene-related peptide in human skin are compatible with a role for these two peptides in neurogenic inflammation. The inflammatory effects of substance P in human skin are inhibited by antihistamines. The possible role of the mast cell in neurogenic inflammation is discussed.     

No release of histamine and substance P in capsaicin-induced neurogenic inflammation in intact human skin in vivo: a microdialysis study

Background Studies in rodents ‘skin have indicated substance P to be the main inflammatory mediator involved in neurogenic inflammation, acting partly by release of histamine from skin mast cells. The mediators released in neurogenic inflammation in human skin remain to be determined. Objectives To determine the effects of intradermally injected and topically applied capsaicin on the release of histamine and substance P and skin responses in intact human skin in vivo. Methods Extracellular skin levels of histamine and substance P were measured by microdialysis technique and assayed by enzyme and radio immunoassays. Two kinds of dialysis fibres (210μm, 2 kDa, and 500 μm, 20 kDa) were inserted intradermally into forearm skin for studies of histamine release to topically administered capsaicin and intradermally injected capsaicin and substance P. Results Baseline histamine skin levels were 8.0 ± 0.7 nM. Intradermally injected capsaicin (0.3–30μM, 7.5–750 pmol) caused significantly and dose-related flare and pain reactions, but no significant histamine release or weals. Intradermally injected substance P (1 and 3 μM, 25 and 75 pmol) released significant amounts of histamine (peak levels being 90 and 475 nM), evoked weal-and-flare reactions, but did not cause pain. Capsaicin 2% ointment, applied on the skin for 2.5 h, increased skin blood flow by 300–400% as measured by laser Doppler flowmetry, elicited a longstanding burning sensation, but did not release histamine. Substance P-like immunoreactivity (SP-LI) was below the 1.8 pM detection limit following insertion of 20 kDa dialysis fibre and after intradermal injection of capsaicin 3μM. Intradermal injection of injection of 1 μM of substance P increased SP-LI levels to values greater than 4500 pM, confirming the ability of the dialysis fibre to recover this peptide. Conclusions Capsaicin-induced neurogenic activation does not involve the release of histamine from mast cells or detectable amounts of substance P release from sensory nerves in normal human skin in vivo.