Effects of substance P on the spontaneous binding of Salmonella minnesota R345 (Rb) to human peripheral blood lymphocytes

The effects of substance P (SP) on Salmonella minnesota R345 (Rb) binding to human peripheral blood lymphocytes (PBL) were evaluated. Two parameters of bacterial cytoadherence were considered, namely the binding lymphocytes (BL) and the number of bound-bacteria/lymphocyte (BB). The results showed that SP inhibits both BL and BB in a significant manner. Furthermore, distribution of Salmonella binding to CD4+ and CD8+ lymphocytes was studied following SP pretreatment of lymphoid cells. This neuropeptide is able to hamper the bacterial cytoadherence to both T-cell subpopulations and, in particular, the inhibitory effect on the T-suppressor/cytotoxic subset was more pronounced. These findings are discussed in terms of SP intervention in the mechanism of host protection against invading microorganisms.     

Differential effects of substance P on serotonin-modulated spinal nociceptive reflexes

Recent immunohistochemical studies indicate the presence of a bulbospinal substance P (SP) system, as well as a bulbospinal serotonin (5-HT) system, involved in spinal pain transmission. Although electrophysiological studies indicate that SP may modulate the effects of 5-HT on post-synaptic spinal nociceptive neurons, the functional relationship between SP and 5-HT on “pain behavior” remains obscure. To bridge this gap between mechanism and behavior, the purpose of the present study was to determine specific postsynaptic behavioral effects of SP and 5-HT on local spinal nociceptive reflexes in spinally transected animals. Administration of the 5-HT agonists 5-methoxydi-methyltryptamine (5-MeODMT) (0, 0.5, 1.5, 2.0 mg/kg) and quipazine (0, 5, 10, 20 mg/kg) 2 days after transection significantly expanded the receptive field (RF) areas of three spinal reflexes, as previously reported. Intrathecal administration of SP alone (0, 0.25, 2.5, 7.5 ng) also resulted in hyperalgesia, indicated by a significant expansion of the RF areas of all three nociceptive reflexes. However, administration of SP, in animals pretreated with 5-HT agonists, decreased the 5-HT-induced expansion of RF size. Therefore, SP had opposite effects on spinal nociceptive reflexes depending on whether or not the animal was pretreated with 5-HT agonists, i.e., hyperalgesia in the absence of 5-HT agonists, and analgesia in the presence of 5-HT agonists. The two effects of SP on local spinal reflexes may be related to the anatomical organization of the two spinal SP systems: 1) SP released from primary afferents facilitates nociceptive reflexes, and 2) SP associated with the descending bulbospinal system interacts with the descending bulbospinal 5-HT system and inhibits nociceptive reflexes. The present results help explain contradictory literature regarding the effect of SP on spinal nociceptive reflexes.     

Illness-induced hyperalgesia is mediated by spinal neuropeptides and excitatory amino acids

The spinal cord dorsal horn contains neural mechanisms which can greatly facilitate pain. We have recently shown that ‘illness’-inducing agents, such as intraperitoneally administered lipopolysaccharide (LPS; bacterial endotoxin), can produce prolonged hyperalgesia. This hyperalgesic state is mediated at the level of the spinal cord via activation of the NMDA-nitric oxide cascade. However, prolonged neuronal depolarization is required before such a cascade can occur. The present series of experiments were aimed at identifying spinal neurotransmitters which might be responsible for creating such a depolarized state. These studies show that LPS hyperalgesia is mediated at the level of the spinal cord by substance P, cholecystokinin and excitatory amino acids acting at non-NMDA sites. No apparent role for serotonin or kappa opiate receptors was found.     

Cognition in relapsing-remitting multiple sclerosis: a multichannel event-related potential (P300) study

Auditory event-related potentials (AERP) were elicited in 47 patients with relapsing-remitting (RR) multiple sclerosis (MS) and 24 age-matched controls. MS patients had significantly prolonged N2 and P3 latencies as well as low P3 amplitude compared with controls. Seven of them exceeded 3 standard deviations from the control mean values. The observed N2 and P3 alterations are associated with the patients' disability status as it is defined by the Kurtzke expanded disability status scale (EDSS), but are not related to the duration of the disease. A possible cognitive decline as reflected in the observed AERP components alterations in MS patients is subsequently discussed.     

Substance P induces inositol 1,4,5-trisphosphate and intracellular free calcium increase in cultured normal human epidermal keratinocytes

Abstract Substance P is a neuropeptide which is present in peripheral C nerve endings and released from them. Free nerve endings of C nerve are present in human epidermis. The effects of substance P on the transmembrane signaling system of pig epidermal sheets were previously reported. In these studies, a small amount of cells other than keratinocytes contaminated the epidermal sheets and the species difference from human was also noticed. Therefore we investigated the effects of substance P on cultured normal human epidermal keratinocytes. Alteration of intracellular free calcium (Ca²⁺) in single living keratinocytes was studied using an inverted fluorescence microscope and Ca²⁺ -sensitive dye, Fura 2-AM. Treatment of normal human epidermal kertinocytes with substance P resulted in an increase in inositol 1,4,5-trisphosphate and in intracellular Ca²⁺. Substance P inhibited DNA synthesis of the keratinocytes in a dose-dependent manner. These results are consistent with the view that substance P stimulates phosphatidylinositol-4,5-bisphosphate hydrolysis of human keratinocytes, resulting in inositol 1,4,5-trisphosphate-Ca²⁺ signal.     

Increased reactivity to chemical but not to heat noxious stimuli in mice producing anti-idiotypic antibodies for substance P

Mice immunized against anti-substance P (anti-SP) monoclonal antibodies produced anti-SP anti-idiotypic antibodies (SPAb2). In a previous report. SPAb2 antibodies were found to have in vitro biological activity i.e. to behave either as agonists or as antagonists for substance P (SP) depending on the biological test. In this study, the involvement of SPAb2 in vivo biological activity has been tested. Because of the possible implication of SP in the generation and transmission of nociceptive information, we have tested the responsiveness of SPAb2 responding mice in behavioral nociceptive tests. SPAb2 mice showed very small behavioral variations in the hot plate test as compared with a control group of mice immunized against an unrelated monoclonal antibody. In the formalin test, however, SPAb2 mice displayed a significant increase in paw licking time, which was significantly correleted with SPAb2 serum concentration. These results are discussed in terms of the use of SPAb2 as pharmacological tools for studying the biological properties of SP receptors and more generally of auto anti-idiotypic antibodies in modulating behavior responses.     

川芎嗪对P2X3受体介导的大鼠伤害性兴奋传入的作用

通过动物痛行为反应(缩足反射)确定局部和鞘内应用川芎嗪(TMP)对ATP等P2X受体激动剂所致大鼠足底急性伤害性行为反应的影响。P2X3受体拮抗剂TNP-ATP(0．3μmol／L)明显抑制P2X受体激动剂ATP(1μmol／L)或α，β-meATP(0．6μmol／L)引起的大鼠足底急性伤害性反应。大鼠足底局部应用TMP(0．1-10mmol／L)剂量依赖性地对ATP(1μmol／L)或α，β-meATP(0．6μmol／L)引起的伤害性反应具有抑制作用。鞘内应用TMP(50mmol／L)对ATP(1μmol／L)或α，β-meATP(0．6μmol／L)引起的伤害性反应具有抑制作用。结果表明，TMP可通过阻断P2X3受体介导的伤害性兴奋传入抑制P2X受体激动剂引起的大鼠足底急性伤害性反应。     

Diadenosine polyphosphate (ApxA) as new neurotransmitters

The presence of diadenosine polyphosphates (Ap_xA), diadenosine tetraphosphate (Ap₄A), diadenosine pentaphosphate (Ap₆A), and diadenosine hexaphosphate (Ap₆A), has been described in secretory granules of chromaffin cells, Torpedo synaptic vesicles, and rat brain synaptosomes. The release of these compounds by the action of secretagogues and depolarizing agents, in the presence of calcium, increases their importance as active neurotransmitters. Two high affinity receptors have been described in the three neural models, with Kd values ranging from 0.08 to 0.40 nM for the first binding site and from 5.6 to 18nM for the second lower affinity binding site. Both binding sites exhibit a P_2y-like profile in chromaffin cells and Torpedo synaptic terminals and a different pattern in rat brain synaptosomes, suggesting the presence of a novel P₂-purinoceptor tentatively named P_2d. Studies about the second messenger linked to this receptor, in chromaffin cells, demonstrate the mobilization of calcium from internal stores. Ap_xA receptors at the extracellular milieu are responsible for the inhibition of catecholamine release stimulated by secretagogues. Finally, all diadenosine polyphosphates are destroyed by the action of an ecto-phosphodiesterase which, in chromaffin cells, shows Km values ranging from 1 to 4 μM. © 1993 Wiley-Liss, Inc.     

Plasma kinetics of 125I-labelled amyloid P component in {beta}2M amyloidosis: A possible approach to quantitate disease activity

Dialysis amyloidosis is one of the most incapacitating complicationsof long-term dialysis treatment. Quantitative assessment ofamyloid deposition using radiolabelled tracers has been recentlyproposed but convincing evidence of its validity in uraemicpatients remains to be provided. We studied the plasma kineticsof i.v. administered ¹²⁵I-labelled serum amyloid P component(¹²⁵I-SAP) in 20 chronic haemodialysis patients compared withthose of nine healthy volunteers and three non-dialysed patientswith systemic amyloidosis. Plasma clearance of the tracer wasabnormal in 17 of 20 dialysis patients in whom plasma radioactivitydeclined in a bi-exponential mode, in contrast to the single-exponentialslope observed in all healthy controls. ¹²⁵I-SAP plasma half-lifeof the second component, probably reflecting metabolic clearance,was significantly prolonged in these dialysis patients comparedwith the healthy controls (35.3 versus 24.6 h, P<0.001).Among the long-term haemodialysis patients the calculated extravasculardistribution of ¹²⁵I-SAP was significantly greater in thosewith severe arthropathy than in asymptomatic patients. Thesefindings demonstrate for the first time that SAP clearance isdisturbed in haemodialysis patients due to both failing renalelimination and retention in extravascular sites. The extravasculardiffusion is greatly enhanced in patients with clinical evidenceof amyloidosis. Therefore the study of plasma ¹²⁵I-SAP kineticspromises to be a valuable tool to quantitate the extent of amyloidosis.     

Identification of N2 as a metabolite of acetylhydrazine in the rat

 In the pathogenesis of isoniazid-induced hepatic injury, cytochrome P450-dependent metabolic activation of the metabolite, acetylhydrazine (AcHz), is the crucial step. Exhalation of [¹⁴C]-carbon dioxide has previously been used to quantify indirectly this pathway. In contrast, according to the current concept of AcHz bioactivation, molecular nitrogen is produced directly, but has not yet been identified. Here, we measured [¹⁵N]-nitrogen and ¹⁴CO₂ exhalation, after the administration of [¹⁵N₂]-[¹⁴C]-AcHz, in rats. Laser magnetic resonance (LMR) spectroscopy, a new sensitive and specific technique for the measurement of ¹⁵N and ¹⁴N in gas samples, was used. To demonstrate the involvement of cytochrome P450, rats were treated with phenobarbital (PB) or PB + cobalt(II) chloride (CoCl₂) (n=3 in each group). Time-dependent ¹⁵N₂ exhalation differed significantly between treatment groups (p<0.001). At 240 min, cumulative exhalation of ¹⁵N was 1.92±0.43% (mean±SE) of the dose in the control group, 2.53±0.23% in the PB group, and 1.00±0.15% in the PB+CoCl₂ group (p<0.05 compared to controls, p<0.01 compared to PB). Cumulative exhalation of ¹⁴CO₂ in 24 h ranged from 15.1 to 21.9%, with no significant difference between treatment groups. In conclusion, N₂ is a metabolite of AcHz. N₂ formation reflects the cytochrome P450-mediated activation of AcHz and can be used as an index of this pathway. Generally, LMR spectroscopy is valuable for monitoring any N₂-liberating process in vivo. Received: 14 March 1995/Accepted: 15 August 1995