Substance P augments nitric oxide production and gene expression in murine macrophages

Neurokinin receptors and their implications in various autoimmune diseases

Neurokinin receptors belong to the GPCRs family and are ubiquitously expressed throughout the nervous and immune systems. Neurokinin receptors in coordination with neurokinins playing an important role in many physiological processes, including smooth muscle contraction, secretion, proliferation, and nociception. They also contribute to various disease conditions such as inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, psoriasis, and cancer. Neurokinin receptors antagonist are potent and highly selective and showing success in treating chemotherapy-induced nausea and vomiting. In this review, discuss the various neurokinin receptor expression on immune cells and their importance in various inflammatory and autoimmune diseases and their therapeutic importance.

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The Neurokinin receptor is an important regulatory mechanism to control the neuronal and immune systems.

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Various neurokinin receptors (NK1R, NK2R, and NK3R) are expressed in neurons and cells of the immune system.

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Substance P (SP) controls the differentiation and function of immune cells.

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SP-NK1R receptor signaling shows substantial cross-talk between neuronal and immune systems in inflammation and autoimmunity.

TRIM28/TIF1β and Fli-1 negatively regulate peroxynitrite generation via DUOX2 to decrease the shedding of membrane-bound fractalkine in human macrophages after exposure to substance P

The chemokine fractalkine is synthesized as a membrane-bound protein, but studies have shown that serum levels of soluble fractalkine are elevated in inflammatory and autoimmune diseases. Patients with autoimmune diseases also have increased serum levels of neuropeptide substance P (SP). The shedding activity of the ADAM family is induced by peroxynitrite, but that of SP is unclear. Treatment of human macrophages with SP upregulated levels of membrane-bound fractalkine. Interestingly, small interfering RNA (siRNA) for DUOX2 further increased membrane-bound fractalkine but decreased soluble fractalkine compared with cells treated with SP alone. SP induced nitric oxide 2/inducible nitric oxide synthase (NOS2/iNOS) mRNA and increased levels of nitrotyrosine, a biomarker of peroxynitrite, whereas transfection with DUOX2 siRNA blunted upregulation of nitrotyrosine. Most importantly, N(ω)-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor) decreased protein levels of nitrotyrosine and concomitantly increased expression of membrane-bound fractalkine after exposure to SP. As for the signaling pathway of TGFβ1 (an inhibitor of iNOS mRNA expression), silencing of RNA for TAK-1 upregulated membrane-bound fractalkine, but silencing of RNA for the Smad family did not. Interfering RNA of transcription factor specificity protein 1 (Sp1) upregulated protein levels of TGFβ1/LAP. Most importantly, double transfection with siRNA for Sp1 and TRIM28/TIF1βor Fli-1 led to a significant increase in TGFβ1/LAP levels and a corresponding reduction of NOS2/iNOS, which inhibited the shedding of membrane-bound fractalkine. In conclusion, TRIM28/TIF1β and Fli-1 negatively regulate TGFβ1 expression to upregulate the generation of peroxynitrite, leading to increased shedding of membrane-bound fractalkine induced by SP.

Neuropeptide substance P and the immune response

Substance P is a peptide mainly secreted by neurons and is involved in many biological processes, including nociception and inflammation. Animal models have provided insights into the biology of this peptide and offered compelling evidence for the importance of substance P in cell-to-cell communication by either paracrine or endocrine signaling. Substance P mediates interactions between neurons and immune cells, with nerve-derived substance P modulating immune cell proliferation rates and cytokine production. Intriguingly, some immune cells have also been found to secrete substance P, which hints at an integral role of substance P in the immune response. These communications play important functional roles in immunity including mobilization, proliferation and modulation of the activity of immune cells. This review summarizes current knowledge of substance P and its receptors, as well as its physiological and pathological roles. We focus on recent developments in the immunobiology of substance P and discuss the clinical implications of its ability to modulate the immune response.

The anti-inflammatory properties of Satureja khuzistanica Jamzad essential oil attenuate the effects of traumatic brain injuries in rats

Traumatic brain injury (TBI) is a major health concern affecting the general public as well as military personnel. However, there is no FDA-approved therapy for the treatment of TBIs. In this work, we investigated the neurotherapeutic effects of the well-known natural Iranian medicine Satureja Khuzistanica Jamzad (SKJ) essential oil (SKEO) on the outcomes of diffused experimental TBI, with particular attention paid to its anti-inflammatory and anti-apoptotic effects. Male Wistar rats were treated with doses of 50, 100 and 200 (mg/kg, i.p) SKEO after induction of diffused TBIs. The results showed that injecting SKEO (200 mg/kg) 30 minutes after TBI significantly reduced brain oedema and damage to the blood-brain barrier (BBB) and limited the post-TBI increase in intracranial pressure. The veterinary coma scale (VCS) scores significantly improved in the treatment group. Also, inflammatory marker assays showed reduced levels of TNF-α, IL-1β, and IL-6 and increased IL-10 in the treated groups. Moreover, the immunohistochemical results indicated that SKEO not only reduced neuronal death and BBB permeability but also affected astrocytic activation. Overall, our data indicate potential clinical neurological applications for SKEO.

Neurotensin modulates the migratory and inflammatory response of macrophages under hyperglycemic conditions

Diabetic foot ulcers (DFUs) are characterized by an unsatisfactory inflammatory and migratory response. Skin inflammation involves the participation of many cells and particularly macrophages. Macrophage function can be modulated by neuropeptides; however, little is known regarding the role of neurotensin (NT) as a modulator of macrophages under inflammatory and hyperglycemic conditions. RAW 264.7 cells were maintained at 10/30 mM glucose, stimulated with/without LPS (1 μg/mL), and treated with/without NT(10 nM). The results show that NT did not affect macrophage viability. However, NT reverted the hyperglycemia-induced impair in the migration of macrophages. The expression of IL-6 and IL-1β was significantly increased under 10 mM glucose in the presence of NT, while IL-1β and IL-12 expression significantly decreased under inflammatory and hyperglycemic conditions. More importantly, high glucose modulates NT and NT receptor expression under normal and inflammatory conditions. These results highlight the effect of NT on cell migration, which is strongly impaired under hyperglycemic conditions, as well as its effect in decreasing the proinflammatory status of macrophages under hyperglycemic and inflammatory conditions. These findings provide new insights into the potential therapeutic role of NT in chronic wounds, such as in DFU, characterized by a deficit in the migratory properties of cells and a chronic proinflammatory status.

Endothelial nitric oxide synthase mediates cutaneous vasodilation during local heating and is attenuated in middle-aged human skin

Local skin heating is used to assess microvascular function in clinical populations because NO is required for full expression of the response; however, controversy exists as to the precise NO synthase (NOS) isoform producing NO. Human aging is associated with attenuated cutaneous vasodilation but little is known about the middle aged, an age cohort used for comparison with clinical populations. We hypothesized that endothelial NOS (eNOS) is the primary isoform mediating NO production during local heating, and eNOS-dependent vasodilation would be reduced in middle-aged skin. Vasodilation was induced by local heating (42°C) and during acetylcholine dose-response (ACh-DR: 0.01, 0.1, 1.0, 5.0, 10.0, 50.0, 100.0 mmol/l) protocols. Four microdialysis fibers were placed in the skin of 24 men and women; age cohorts were 12 middle-aged (53 ± 1 yr) and 12 young (23 ± 1 yr). Sites served as control, nonselective NOS inhibited [N(G)-nitro-l-arginine methyl ester (l-NAME)], inducible NOS (iNOS) inhibited (1400W), and neuronal NOS (nNOS) inhibited (N(ω)-propyl-l-arginine). After full expression of the local heating response, l-NAME was perfused at all sites. Cutaneous vascular conductance was measured and normalized to maximum (%CVC(max): Nitropress). l-NAME reduced %CVCmax at baseline, all phases of the local heating response, and at all ACh concentrations compared with all other sites. iNOS inhibition reduced the initial peak (53 ± 2 vs. 60 ± 2%CVC(max); P < 0.001); however, there were no other differences between control, nNOS-, and iNOS-inhibited sites during the phases of local heating or ACh-DR. When age cohorts were compared, NO-dependent vasodilation during local heating (52 ± 6 vs. 68 ± 4%CVC(max); P = 0.013) and ACh perfusion (50 mmol/l: 83 ± 3 vs. 93 ± 2%CVC(max); 100 mmol/l: 83 ± 4 vs. 92 ± 3%CVC(max); both P = 0.03) were reduced in middle-aged skin. There were no differences in NOS isoform expression obtained from skin biopsy samples between groups (all P > 0.05). These data suggest that eNOS mediates the production of NO during local heating and that cutaneous vasodilation is attenuated in middle-aged skin.

Immunomodulatory role of substance P in the wall lizard Hemidactylus flaviviridis: an in vitro study

Present in vitro investigation for the first time in ectotherms demonstrated the immunomodulatory role of substance P in the wall lizard Hemidactylus flaviviridis. Substance P inhibited the percentage phagocytosis and phagocytic index of lizard splenic phagocytes. Inhibitory effect of substance P was completely blocked by NK-1 receptor antagonist spantide I, indicating the NK-1 receptor mediated action. Further, NK-1 receptor-coupled downstream signaling cascade involved in controlling phagocytosis was explored using inhibitors of adenylate cyclase (SQ 22536) and protein kinase A (H-89). Both the inhibitors, in a concentration-related manner decreased the suppressive effect of substance P on phagocytosis. In addition, substance P treatment caused an increase in intracellular cAMP level in splenic phagocytes. Taken together, it can be suggested that substance P via NK-1 receptor-coupled AC-cAMP-PKA pathway modulated the phagocytic activity of splenic phagocytes in wall lizards.

Tachykinin receptor modulation of cyclooxygenase-2 expression in human polymorphonuclear leucocytes

BACKGROUND AND PURPOSE

We investigated the ability of natural and synthetic selective NK receptors agonists and antagonists to modulate cyclooxygenase-2 (COX-2) expression in human polymorphonuclear leucocytes (PMNs).

EXPERIMENTAL APPROACH

The presence of all three tachykinin in PMNs was assessed by Western blot and PCR techniques. Natural and synthetic ligands selective for the tachykinin receptors were used to modulate COX-2 protein (measured with Western blotting) and activity [as prostaglandin E(2) (PGE(2)) output]. Effects of substance P (SP) on phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-kappaB) activation were studied to analyse the signalling pathway involved in COX-2 up-regulation mediated by SP.

KEY RESULTS

Stimulation of NK receptors with the natural ligands SP, neurokinin A (NKA) and neurokinin B, in the pmol.L(-1)-micromol.L(-1) concentration range, modulated COX-2 expression and PGE(2) release in a concentration- and time-dependent manner. Experiments with synthetic selective agonists [Sar(9), Met(O(2))(11)]SP, [beta-Ala(8)] NKA(4-10), senktide or selective antagonists L703,606, SR48,968 or SR142801, confirmed that COX-2 up-regulation was mediated by NK receptors. We found that mainly p38, p42 and p46 MAPKs were phosphorylated by SP and SB202190, PD98059 and SP600125, which are selective inhibitors of these kinases, blocked SP-induced COX-2 expression. SP also induced nuclear translocation of NF-kappaB concentration-dependently, with a maximum effect at 1 nmol.L(-1).

CONCLUSIONS AND IMPLICATIONS

Human PMNs possess functional NK(1), NK(2) and NK(3) receptors, which mediate the induction of COX-2 expression and NF-kappaB activation by SP.

Substance P enhances wound closure in nitric oxide synthase knockout mice

INTRODUCTION

The neuropeptide, substance P (SP), up-regulates nitric oxide production (NO). The purpose of this study was to determine whether SP enhances response to cutaneous injury in nitric oxide synthase knockout (NOS null) mice.

METHODS

We studied mice with targeted deletions of the 3 NOS genes, neuronal NOS, inducible NOS, or endothelial NOS. Full thickness dorsal wounds were treated daily (d 0-6) with topical SP or normal saline (NaCl). Wounds were analyzed by flow cytometry for macrophage, leukocyte, endothelial, and dendritic cells. Healing time and wound epithelialization were compared using analysis of variance.

RESULTS

Wound closure in the 3 NOS null mice was slower than the control mice (P < 0.05). SP treatment enhanced wound closure in NOS null mice (P < 0.02). NOS null wounds exhibited reduced inflammation. SP increased macrophage, leukocyte, and dendritic cell densities at d 3 and d 7 (P < 0.05) in all NOS null mice. SP increased endothelial cell number in neuronal NOS and inducible NOS null mice, but not in endothelial NOS null mice (P > 0.05).

CONCLUSIONS

SP ameliorated the impaired wound healing response observed in NOS null mice by enhancing wound closure kinetics and epithelialization. SP increased inflammatory cell density in the wounds supporting the essential role of inflammatory cells, especially macrophages, in wound repair.

Neuropeptides regulate expression of matrix molecule, growth factor and inflammatory mediator mRNA in explants of normal and healing medial collateral ligament

Denervation degrades normal ligament properties and impairs ligament healing. This suggests that secreted neuromediators, such as neuropeptides, could be modulating cell metabolism in ligament and scar tissue. To test this hypothesis we investigated the effect of exogenous substance P (SP), neuropeptide Y (NPY) or calcitonin gene-related peptide (CGRP) on the mRNA levels for proteins associated with inflammation, angiogenesis, and matrix production in tissue-cultured specimens of normal and injured medial collateral ligament. SP and NPY induced increased mRNA levels for several inflammatory mediators in the 2-week post-injury specimens. All three neuropeptides induced decreases in mRNA levels for healing-associated growth factors and matrix molecules, including basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and collagen types I and III. The results indicate that neuropeptides strongly influence the metabolic activity of cells in healing ligament, particularly at early time points after injury.

The effect of substance P on nitric oxide production by HSV-1 infected macrophages

The regulatory role of neuro-immune pathways in various infectious disease states is an interesting area of investigation due to its important therapeutic potential. In this study the effect of substance P (SP) on nitric oxide (NO) production of HSV-infected macrophages and its relation with incubation time and also the cytopathic effect of virus in the presence of SP are considered. As we have observed, substance P enhances NO production both in HSV- and mock-infected macrophages and this effect has been diminished or disappeared after 24 h. It has also been observed that SP enhances the cytopathic effect of HSV in a time dependent manner with the most effect at 10 h after stimulation with SP. We have also observed that HSV-1 cytopathic effect has not been significantly affected by pretreatment of macrophages with SP (2, 10 or 24 h before HSV infection). It can be concluded that the neurotransmitter SP has a significant role in modulating macrophage function and thus innate immunity processes in healthy and HSV-infected cells.

Inflammatory cell accumulation in traumatic neuromas of the human lingual nerve

OBJECTIVE

To quantify the accumulation of inflammatory cells in traumatic neuromas of the human lingual nerve, and to establish any correlation with the patients' reported symptoms of dysaesthesia.

DESIGN

Using fluorescence immunohistochemistry, the extent of any chronic inflammatory infiltrate was quantified in human lingual neuroma specimens removed from 24 patients at the time of microsurgical nerve repair. A pan-leucocyte marker (CD45) and a specific macrophage marker (CD68) were used, and comparisons made between neuromas-in-continuity (NICs) and nerve-end neuromas (NENs) in patients with or without symptoms of dysaesthesia.

RESULTS

CD68 and CD45 labelling was significantly associated with areas of viable nerve tissue in neuromas and the CD68 labelling was significantly higher in NICs than NENs. CD68 labelling density tended to decrease with increasing time after the initial nerve injury, but this correlation was only significant for labelling associated with viable nerve tissue in NENs. No significant difference was found between the level of CD68 or CD45 labelling in patients with or without symptoms of dysaesthesia.

CONCLUSION

This study has demonstrated the presence of inflammatory cells within traumatic neuromas of the human lingual nerve. These cells were found to be closely associated with regions of viable nerve tissue, but there was no correlation with the patients' clinical symptoms.

Bovine alveolar macrophage neurokinin-1 and response to substance P

In this study bovine alveolar macrophage neurokinin-1 (NK-1) and the in vitro response to substance P (SP) exposure were investigated. Bovine alveolar macrophage membrane extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotted using anti-NK-1 antiserum demonstrated the presence of an approximately 60kDa band. Phagocytosis of fluorescent bioparticles by SP-exposed macrophages was 39% greater than that of non-exposed macrophages (P=0.0089). Likewise, there was 28% greater TNF production by macrophages following SP exposure compared to non-exposed controls (P=0.116). These results suggest that bovine alveolar macrophages respond to SP at least in part by enhancing phagocytosis and TNF production.

Breaking or making immunological privilege in the central nervous system: the regulation of immunity by neuropeptides

Immune privilege in the central nervous system (CNS) is not maintained by immune ignorance of the CNS, but by CNS control over inflammatory processes. In this review we examine the role neuropeptides play in maintenance of immune privilege in the CNS. Vasoactive intestinal peptide, alpha-melanocyte-stimulating-hormone, neuropeptide Y, and somatostatin are members of an anti-inflammatory repertoire of immune modulators, while substance P acts to break immune privilege and promote inflammation in the CNS. Here we focus both on cellular responses to these neuropeptides and the role these peptides play in immune privilege as it relates to CNS autoimmunity.

Neuroprotective effects of cyclooxygenase-2 inhibitor celecoxib against toxicity of LPS-stimulated macrophages toward motor neurons

AIM

To establish an in vitro injured motor neuronal model and investigate the neuroprotective effects and possible mechanism of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, on this model.

METHODS

After macrophages were stimulated with lipopolysaccharide (LPS)+interferon-gamma (IFN-gamma) in the presence or absence of celecoxib for 24 h, the cell-free supernatant of LPS-stimulated macrophages was transferred to the culture of NSC34 cells. Viability of NSC34 cells was assessed by MTT assay after a further 24 h and 72 h incubation. After macrophages were stimulated by LPS+IFN-gamma for 12 h or 24 h, the release of prostaglandin E2 (PGE2), nitric oxide (NO), reactive oxygen species (ROS), tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) from macrophages was measured by radioimmunoassay, Griess assay, fluorescence assay and enzyme-linked immunosorbent assay, respectively. The mRNA levels of COX-2, inducible nitric oxide synthase (iNOS), TNF-alpha and IL-1beta in macrophages were determined by reverse transcription-polymerase chain reaction after macrophages were stimulated for 6 h and 12 h.

RESULTS

The supernatant of LPS-stimulated mouse macrophages induced the death of NSC34 cells and celecoxib protected the NSC34 cells against this toxicity. The LPS-induced increases in the release of PGE2, NO, TNF-alpha and IL-1beta from macrophages were attenuated by pre-treatment with celecoxib. However, celecoxib showed no effect on the ROS levels upregulated by LPS+IFN-gamma in the macrophage supernatant. The mRNA levels of COX-2, iNOS, TNF-alpha and IL-1beta were increased in LPS-activated macrophages and, except COX-2, reduced by pre-treatment with celecoxib.

CONCLUSION

An in vitro injured motor neuronal model was established by using the toxicity of LPS-stimulated mouse macrophages toward motor neuronal NSC34 cells. In this model, celecoxib exerted neuroprotective effects on motor neurons via an inhibition of the neurotoxic secretions from activated macrophages.

Expression of inducible nitric oxide synthase mRNA and nitric oxide production during the development of liver abscess in hamster inoculated with Entamoeba histolytica

The present study analyzed iNOS and eNOS mRNA expression and NO production during development of hepatic abscess caused by Entamoeba histolytica trophozoites. One 374-bp sequence, which displayed 88% identity to mammalian iNOS protein, was isolated from LPS-stimulated peritoneal hamster macrophages. A separate 365-bp cDNA sequence showed 99% identity with eNOS protein. iNOS mRNA was detected in hamsters during formation of amoebic liver abscesses, but not in control hamsters. eNOS mRNA expression was not modified. Serum nitrite concentration in hamsters infected with E. histolytica was 33 +/- 6 microM, in control hamsters was 20 +/- 3 microM. The study shows that iNOS mRNA expression and NO production are induced by E. histolytica trophozoites during amoebic liver abscess formation. However, in spite of iNOS mRNA expression and NO production, E. histolytica trophozoites induced liver abscess formation in hamster.

Direct antimicrobial properties of substance P

The structural similarity between substance P (SP, Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH(2)) and Arg/Pro rich bactericidal peptides suggests a possible direct effect of SP on invasive microbes. We now present evidence that substance P possesses direct antimicrobial activity, highest against S. aureus. A substance P antagonist also possesses such activity but while less potent than substance P agonist S. aureus, is more potent than substance P against C. albicans. Our data also show that the endogenous peptides bradykinin and neurotensin, that also play role in modulation of the host-defense system in situ, have antimicrobial properties but are less potent than substance P.

Difference in penetration of horseradish peroxidase tracer as a foreign substance into the peri-implant or junctional epithelium of rat gingivae

Horseradish peroxidase (HRP) tracer was applied to the gingival sulcus of implants or natural teeth at 5, 25, or 50 mg/ml to investigate the sealing capacities of the peri-implant epithelium (PIE) and junctional epithelium (JE); the extent of HRP penetration was observed under electron microscopy. A Ti-6Al-4V implant was inserted either immediately (immediate implantation) or 2 weeks (delayed implantation) after extraction of the maxillary left first molar of rats. The JE of the right molar was used as a control. Although the whole PIE of undecalcified sections appeared to be attached to the implant surface, electron microscopically, the internal basement lamina (IBL) and hemidesmosomes were deficient in the coronal-middle region of the PIE. There were extensive extracellular deposits of HRP in the intercellular spaces between PIE cells, and HRP was blocked to some extent by the lamina lucida and lamina densa of the external basal lamina and basal cell junction. HRP was detected in the connective tissue under the PIE, but was not found in the connective tissue under the JE. Intracellularly, HRP was found in the vesicles and granules of PIE cells and JE cells. These were fewer in number in PIE cells than in JE cells. There were no differences between the findings for immediate and delayed implantation. The results indicate that a deficiency in the IBL permitted penetration of HRP from the gingival sulcus into the connective tissue under the PIE, and suggest that the endocytotic capacity of PIE cells is inferior to that of JE cells.

Characterization of the mechanism underlying stonustoxin-mediated relaxant response in the rat aorta in vitro

Stonustoxin (SNTX) is a lethal factor isolated from the venom of the stonefish Synanceja horrida. Although SNTX exhibits a multitude of biological activities, the primary cause of death upon administration of the toxin is attributed to marked hypotension. We investigated the possible mechanisms underlying the vascular hyporeactivity of this novel toxin. Cumulative doses of SNTX (5-320 ng/mL) induced concentration-dependent relaxation in phenylephrine (PE)--precontracted rat aortic rings with intact endothelium. Endothelium removal abolished the relaxation induced by SNTX. Tetraethylammonium (TEA), an inhibitor of K(+) channels, partially inhibited SNTX-induced relaxation. Similarly, SNTX-induced relaxation was partially attenuated by the SP receptor antagonist (NATB), whereas the inducible iNOS inhibitor, AMT-HCl, completely abolished the relaxation caused by SNTX. From the results obtained, it can be postulated that a component of SNTX-mediated vasorelaxation is via binding of either SNTX or SP to the SP receptors that are located on the endothelial cells. Occupation of these SP receptors causes subsequent production of NO and activation of K(+) channels, thus leading to vasorelaxation of the rat aortic rings.

Regulation of apoptosis by somatostatin and substance P in peritoneal macrophages

Recent studies have shown that somatostatin (SOM) inhibits interleukin 6 (IL-6) and interferon gamma (IFNgamma) production by lymphocytes and peritoneal macrophages, whereas substance P (SP) enhances these cytokines production. To define the mechanism of the cytokine production enhancements and inhibitions by SOM and SP, we examined the expression of apoptosis modulator, p53, Bcl-2, Bax, inducible nitric oxide synthase (iNOS), Fas, caspase-8 and nitric oxide (NO) in thioglycolate-elicited peritoneal macrophages. SOM caused up-regulation of p53, Bcl-2, Fas and caspase-8 activities, and down-regulation of iNOS expression and NO production. On the other hand, SP slightly induces p53 and highly induces Bcl-2, iNOS expression and NO production. These data suggest that apoptosis by SOM may occur by a Bax- and NO-independent p53 accumulation, and through Fas and caspase-8 activation pathways, and that the inducible expression of Bcl-2 and NO production by SP may contribute to prevent the signals of apoptosis by Bax, and via Fas and caspase-8 activation.

Nitric oxide involvement in the anxiogenic-like effect of substance P

This study investigates whether nitric oxide (NO) is involved in the anxiogenic profile of action of substance P (SP) in mice in the elevated plus-maze (EPM). Adult Swiss mice were injected with NOS inhibitors such as L-NOARG (20 nmol/kg) i.p., L-NAME (3 nmol per site), 7-NI (0.25 nmol per site) i.c.v. or vehicle (NaCl 0.9% i.p. or PBS i.c.v.). About 30 min (i.p. pretreatment) or 5 min later (i.c.v. pretreatment), the animals received i.c.v. injections of SP (10 pmol) or phosphate buffered saline (PBS) (2 microl). Afterwards, they were observed in the EPM. SP per se reduced the time spent on open arms, an anxiogenic-like effect. This effect was reverted by different NOS inhibitors and the NO donor. NOS inhibitors had no influence on the EPM parameters but the NO-releasing compound SNAP, as well as its parent thiol NAP, increased the animals' locomotor activity. 8-Br-cGMP (20 nmol), a permeable cGMP analog, promoted an anxiogenic-like effect per se and enhanced the SP effect on the EPM. Altogether, these results suggest a putative NO role in the mediation of the anxiogenic-like effect of SP.

Nitric oxide synthase neurons in the rodent spinal cord: distribution, relation to Substance P fibers, and effects of dorsal rhizotomy

The indirect immunofluorescent method was employed to investigate the distribution of neuronal nitric oxide synthase-like immunoreactivity(nNOS-LI) in the spinal cord of the golden hamster and to compare it to data obtained from rats. Immunoreactive neurons were found throughout the cervico-sacral extent in the dorsal horn (mainly in laminae I-III) and in the preganglionic autonomic regions, i.e., the sympathetic intermediolateral nucleus (IML), lateral funicle (LF), intercalated region (IC), the area surrounding the central canal (CA), and the sacral preganglionic parasympathetic cell group. While the distribution of immunoreactive cells was generally similar in both species, some differences were observed. For example in the hamster LF, a higher percentage of stained neurons was seen than in the IML, while the situation was rather inverse in the rat. In order to study the coincidence of nNOS-LI in the population of preganglionic sympathetic neurons (PSN) that innervate the superior cervical ganglion (SCG), these were identified by retrograde axonal transport of fluoro-gold (FG) following unilateral injection into the SCG. PSN were localized ipsilateral to the injection site mainly in the IML and LF of spinal segments C7-Th4. The portion of double-labeled neurons of the IML were lower in hamster (17% in C7, 34% in C8) of FG-labeled cells) than in rat (47% in C8, 77% in Th2), while in the LF of segments C8-Th2 in both species the majority of FG-neurons contained nNOS. While only very few double-labeled neurons were detected in the IC in hamster and rat, a striking difference was observed in the CA, where no double-labeled neurons were found in hamster, but up to 50% in rat. Double immunofluorescence detection of nNOS and substance P (SP) showed that in both the autonomic regions and the dorsal horn, SP-LI fibers and puncta were present in close spatial relationship to nNOS-LI cell bodies. These results were basically identical in the hamster and rat. Unilateral transection of the dorsal roots of segments C6-Th2 in rats resulted in a clear reduction of SP-LI structures in the dorsal horn 5 days after rhizotomy, but not in the autonomic regions. Compared to the unlesioned side, the numbers of nNOS-LI neurons in the superficial laminae of the dorsal horn were reduced to 32-46% in the lesioned segments, and to 53% and 87%, respectively, in the two segments cranial to the rhizotomized segments but remained unchanged caudally to the lesion. Numbers of nNOS-LI cell bodies in the autonomic regions were not altered following dorsal root transection. The present study provides data on the widespread distribution of nNOS in the spinal cord of golden hamster and describes the partial coincidence of the enzyme in PSN. The effects of dorsal rhizotomy on nNOS-LI neurons in the dorsal horn reveal that primary-afferent fibers provide a stimulatory influence on neurons of the dorsal horn to generate the gaseous neuroactive substance, nitric oxide.

Special feature for the Olympics: effects of exercise on the immune system: neuropeptides and their interaction with exercise and immune function

It is known today that the immune system is influenced by various types of psychological and physiological stressors, including physical activity. It is well known that physical activity can influence neuropeptide levels both in the central nervous system as well as in peripheral blood. The reported changes of immune function in response to exercise have been suggested to be partly regulated by the activation of different neuropeptides and the identification of receptors for neuropeptides and steroid hormones on cells of the immune system has created a new dimension in this endocrine-immune interaction. It has also been shown that immune cells are capable of producing neuropeptides, creating a bidirectional link between the nervous and immune systems. The most common neuropeptides mentioned in this context are the endogenous opioids. The activation of endogenous opioid peptides in response to physical exercise is well known in the literature, as well as the immunomodulation mediated by opioid peptides. The role of endogenous opioids in the exercise-induced modulation of immune function is less clear. The present paper will also discuss the role of other neuroendocrine factors, such as substance P, neuropeptide Y and vasoactive intestinal peptide, and pituitary hormones, including growth hormone, prolactin and adrenocorticotrophin, in exercise and their possible effects on immune function.

Special feature for the Olympics: effects of exercise on the immune system: neuropeptides and their interaction with exercise and immune function

It is known today that the immune system is influenced by various types of psychological and physiological stressors, including physical activity. It is well known that physical activity can influence neuropeptide levels both in the central nervous system as well as in peripheral blood. The reported changes of immune function in response to exercise have been suggested to be partly regulated by the activation of different neuropeptides and the identification of receptors for neuropeptides and steroid hormones on cells of the immune system has created a new dimension in this endocrine-immune interaction. It has also been shown that immune cells are capable of producing neuropeptides, creating a bidirectional link between the nervous and immune systems. The most common neuropeptides mentioned in this context are the endogenous opioids. The activation of endogenous opioid peptides in response to physical exercise is well known in the literature, as well as the immunomodulation mediated by opioid peptides. The role of endogenous opioids in the exercise-induced modulation of immune function is less clear. The present paper will also discuss the role of other neuroendocrine factors, such as substance P, neuropeptide Y and vasoactive intestinal peptide, and pituitary hormones, including growth hormone, prolactin and adrenocorticotrophin, in exercise and their possible effects on immune function.