Stimulatory Effect Of Substance Research Articles

Substance P enhances soluble ICAM‐1 release from adult rat cardiac fibroblasts by a p42/44 MAPK‐ and PKC‐mediated mechanism

Substance P, a pro-inflammatory neuropeptide, is released from cardiac peptidergic nerves under conditions like ischemia but whether it modulates inflammatory processes in the heart remains unexplored. This study demonstrates for the first time that substance P augments the production of the soluble form of intercellular adhesion molecule-1, sICAM-1, by adult rat cardiac fibroblasts. However, RT-PCR showed no concomitant increase in ICAM-1 transcript levels, suggesting that the increase in sICAM-1 may involve post-transcriptional/translational mechanisms. Use of pharmacological inhibitors revealed that the stimulatory effect of substance P on sICAM-1 production is mediated by p42/44 MAPK and protein kinase C. Preliminary experiments also showed that the neuropeptide stimulates the production of prostaglandin E(2) by cardiac fibroblasts. The findings support the postulation that substance P may modulate multiple inflammatory responses within the myocardium through release of pro-inflammatory mediators from resident fibroblasts.

In vitro substance P-dependent induction of bone marrow cells in common (CD10) acute lymphoblastic leukaemia

The aim of the present research was to investigate the possible in vitro stimulatory effect of substance P (SP) on blasts induction in childhood common acute lymphoblastic leukaemia (ALL). Bone marrow aspirates were incubated with SP receptor agonist or antagonist (spantide) and subsequently assayed for the presence of human interleukin (IL)-1b using ELISA kit. Blast cells incubated with SP receptor agonist were found to result in a significant increase of IL-1b concentration while incubated with spantide resulted in control levels of IL-1b. These findings suggest the novel possible role of SP in blasts proliferation in childhood ALL of common (CD10) origin.

Melatonin inhibits the substance P-induced secretion of vasopressin and oxytocin from the rat hypothalamo-neurohypophysial system: In vitro studies

The aim of the present investigations was to study the influence of substance P (a member of a family of peptides known as tachykinins) on basal and K +-evoked vasopressin (AVP) and oxytocin (OT) release from rat hypothalamo-neurohypophysial system in vitro as well as to determine whether this effect of substance P is sensitive to melatonin. The present results show that substance P stimulates basal AVP and OT release from isolated hypothalamo-neurohypophysial system, when used at the concentrations of 10 −6 and 10 −7 M/l. At the concentration of 10 −9 M/l, however, substance P was found to stimulate the in vitro secretion of AVP, but not that of OT. Melatonin diminished basal release of AVP; it also significantly inhibited the substance P-stimulated secretion of AVP and OT. K +-evoked release of the neurohypophysial hormones was not further modified by either substance P or melatonin. The present results show that the stimulatory effect of substance P on basal release of AVP and OT from rat hypothalamo-neurohypophysial system in vitro is sensitive to inhibitory influence of melatonin.

Stimulatory effects of substance P on CD34 positive cell proliferation and differentiation in vitro are mediated by the modulation of stromal cell function.

Substance P (SP) is a neuropeptide widely distributed in the nervous system. Extensive study has shown SP stimulates production of various cytokines by bone marrow stromal cells, although, the role of SP in hematopoietic phenomena is still unclear. Recently, we established a human cloned stromal cell line, HAS303, which can support hematopoietic stem cell proliferation and differentiation in vitro. We used this culture system to examine the effects of SP. Expression of the mRNAs of neurokinin (NK)-1R, NK-2R and NK-3R, specific SP receptors, on HAS303 cells was demonstrated by the RT-PCR. CD34+ cells isolated from bone marrow were co-cultivated with HAS303 cells in the presence and absence of SP and the total hematopoietic cells and progenitors were counted every 5 days. Introducing SP (10(-8) M) to the co-cultures significantly increased the number of total cells and progenitors compared with control cultures. SP showed no enhancing activity on CD34+ cells cultured alone. SP also stimulated IL-3-dependent colony formation of whole bone marrow MNCs in a soft agar culture system, but showed no such activity on isolated CD34+ cells in this system. These observations suggest that SP stimulated HAS303 cells, activated HAS303 cells, and stimulated the proliferation and differentiation of CD34+ cells. Treating HAS303 cells with SP increased the intracellular Ca2+ concentration and stimulated production of G-CSF, GM-CSF, SCF and IL-6, but not IL-1alpha, IL-1beta and TNF-alpha, but did not enhance proliferation. All these findings suggest that SP mediates hematopoietic cell proliferation and differentiation in vitro by activating stromal cell function.

The neuropeptide substance P activates transcription factor NF-kappa B and kappa B-dependent gene expression in human astrocytoma cells.

The neuropeptide substance P is a major mediator of neurogenic inflammation and immunomodulatory activities within the central and peripheral nervous system. In several cell types, substance P induces the expression of proinflammatory cytokines that have been implicated in the pathogenesis of different neuropathologies. Substance P preferentially binds to NK-1, a receptor of the neurokinin family, but how the receptor-elicited signal is translated into inflammatory gene expression is not yet understood. In this work, we describe that in U373 MG astrocytoma cells, nanomolar concentrations of substance P potently triggered activation of NF-kappa B, a transcription factor involved in the control of cytokine expression and apoptosis. Substance P-induced NF-kappa B activation was associated with the increased mRNA expression and secretion of IL-8, an NF-kappa B-controlled target gene. The stimulatory effect of substance P was specific, since an NK-1-selective receptor antagonist completely prevented NF-kappa B activation in response to substance P, but not IL-1 beta. In addition, we show that the activity of substance P required mobilization of intracellular calcium and formation of reactive oxygen intermediates as second messengers. Our results suggest that NF-kappa B may be an important component controlling neurogenic inflammation within the peripheral and central nervous system.

Galanin and somatostatin inhibition of substance P-induced airway mucus secretion in the rat

Substance P is present in several neurons innervating the lung. Tachykinin receptors are expressed on submucosal gland cells. Substance P is known to be a potent stimulator of airway mucus secretion. In the present study we characterized the effects of galanin and somatostatin on basal and substance P-induced mucus secretion. The stimulatory effect of substance P was concentration-dependent (100 pmol/l: 112%, 1 nmol/l: 120%, 10 nmol/l: 153%, 100 nmol/l: 223%, 1 μmol/l: 275%, 10 μmol/l: 172%) and was inhibited by galanin and somatostatin (1 μmol/l substance P: 277%; 1 μmol/l substance P+1 μmol/l somatostatin: 190%, p < 0.01; 1 μmol/l substance P+1 μmol/l galanin: 206%, p < 0.05). In the presence of lower concentrations of substance P 1 μmol/l somatostatin and 1 μmol/l galanin did not modify mucus secretion. Lower concentrations of galanin and somatostatin did not significantly change mucus secretion stimulated by 1 μmol/l substance P. Both, galanin and somatostatin at 1 μmol/l left basal airway mucus secretion unaltered. These data suggest that mucus secretion into airways is regulated by a complex network of peptidergic stimulators and inhibitors including substance P, somatostatin and galanin.

ROLE OF EXTRACELLULAR CALCIUM IN THE EFFECTS OF SUBSTANCE P AND NEUROKININ A ON GUINEA PIG TRACHEA AND HUMAN BRONCHUS

Whether the influx of calcium through voltage-operated channels is involved in the stimulatory effects of substance P and neurokinin A in airways smooth muscle is not yet firmly established. This question was addressed in the present study using guinea pig trachea and human bronchi suspended in normal or calcium-free Krebs solution and tested with inhibitors of calcium channels. In calcium-free Krebs solution, the myotropic effects of substance P (10(-7) M), neurokinin A (3.10(-8) M), acetylcholine (2.10(-5) M), and histamine (2.10(-5) M) were reduced by 27-57%, while those of potassium chloride and tetraethylammonium were practically abolished. Calcium antagonists such as verapamil or nicardipine, when applied at concentrations of 10(-8)-10(-6) M, inhibited the contractions produced by potassium chloride and tetraethylammonium, whereas higher concentrations (10(-5)-10(-4) M) of both inhibitors were needed to reduce the effects of substance P, neurokinin A, acetylcholine, and histamine. In neither preparation did the calcium agonist Bay K 8644 (10(-6) M) modify the effects of neurokinin A, substance P, acetylcholine, or histamine, but it potentiated potassium chloride's effect on human bronchi. We conclude that transmembrane calcium influx through voltage-operated channels plays a minor role in the stimulatory effects of neurokinins in airways smooth muscle.

Stimulatory effect of substance P on sympathetic ganglia and spinal cord in culture

Studies with organotypic culture of sympathetic ganglia and spinal cord revealed that substance P at concentrations of 10(-5) to 10(-12) M and 10(-5) to 10(-14) M exerts a marked growth-stimulating effect on sympathetic ganglia and spinal cord, respectively. In the presence of substance P, the intensity of sympathetic ganglion growth exceeds control values 3.0-4.8 times. The growth zone size of spinal cord explants increases under these conditions 2.0-5.2-fold. A feasible physiological significance of regulatory peptides in the growth and regeneration of nervous tissue as well as the role of noci-antinociceptive systems in histogenesis and regeneration are discussed.

Stimulatory effect of substance P on the spontaneous release of newly synthesized [ 3H]dopamine from rat striatal slices: A tetrodotoxin-sensitive process

Stritial slices from the rat were continuously superfused with [ 3H]tyrosine in order to estimate the release of newly synthesized [ 3H]dopamine ([ 3H]DA). Substance P (SP) and neuromedin K (NKB) stimulated the spontaneous release of [ 3H]DA when used in concentrations (from 10 −9 M to 10 −7 M). The stimulatory effect of substance P (10 −8M) was prevented completely when slices were superfused with tetrodotoxin (10 −7 M) or the substance P antagonist ( d-Arg 1, d-Pro 2, d-Trp 7,9, Leu 11) substance P (10 −5 M) indicating that the response evoked by substance P was mediated by substance P receptors but that these were not located on DA nerve terminals. In addition, substance P did not modify the stimulatory effect of acetylcholine (ACh) (10 −5M) on the spontaneous release of [ 3H]DA since the effects of substance P (10 −7M) and ACh (10 −5M) were additive.

Effect of substance P on the lower esophageal sphincter of the opossum

Since the original observations by Von Euler and Gaddum, considerable interest has developed regarding the role of substance P in smooth muscle function. The purpose of the present investigation was to evaluate the effect of intravenously administered substance P on the in vivo motor function of the lower esophageal sphincter (LES). Intraesophageal pressures were monitored by an assembly of polyvinyl catheters attached to pressure transducers and a recorder. The catheters were continuously perfused with bubble-free water. Administration of 5, 10, 25, 50, and 100 ng per kg of substance P stimulated the LES, respectively, 16, 32, 57, 147, and 169% above control values. Tetrodotoxin, phentolamine, hexamethonium, methysergide, and bilateral cervical vagotomy did not alter the response of the LES to substance P. Atropine in 40-, 250-, and 500-μg per kg doses significantly but partially inhibited the response of the LES to substance P. It is concluded that substance P is a potent stimulant of the LES. The stimulatory effect of substance P may involve both cholinergic muscarinic and noncholinergic mechanisms. It is conceivable that substance P may be a modulator of LES pressure, although the exact physiological significance is not clear at the present time.

Stimulatory effects of substance P and nerve growth factor (NGF) on neurite outgrowth in embryonic chick dorsal root ganglia

Synthetic Substance P at 10 4 M and Nerve Growth Factor (NGF) at 2 ng ml produced a 3-fold increase in the concentration of cyclic AMP 10 min after addition to cultured chick dorsal root ganglia. Subsequently, increased fiber outgrowth was observed 24 hrs after these additions. Dibutyryl cyclic AMP at 10 −3 M also produced a similar induction of fiber outgrowth. These studies suggest that Substance P and NGF might act by increasing cyclic AMP levels, which may then act as an initial “second messenger”, inducing the morphological differentiation at a later time.

Stimulation of brain adenylate cyclase activity by the undecapeptide substance P and its modulation by the calcium ion

Synthetic substance P stimulated adenylate cyclase activity in particulate preparations from rat and human brain. The concentration of substance P for half maximal stimulation in rat brain was 1.8 · 10 −7 M. The stimulatory effect of substance P on the rat brain adenylate cyclase activity was 88% compared with 48% by noradrenalin, 163% by prostaglandin E 1 and 184% by prostaglandin E 2. Both the basal and substance P-stimulated adenylate cyclase activity in rat brain were inhibited by concentration of Ca 2+ above 10 −6 M. The chelating agent ethyleneglycol-bis-( β-aminoethylether)- N, N′-tetraacetic acid at a concentration of 0.1 mM reduced the basal adenylate cyclase activity by 64% and eliminated the substance P-stimulated activity. The inhibition by ethyleneglycol-bis-( β-aminoethylether)- N, N′-tetraacetic acid was completely reversed by increasing concentrations of Ca 2+.