Remodeling of neural, glial, and tracheal cell populations in the developing Manduca wing

In the rat larynx, plasma exudation and edema formation were studied by light and electron microscopy after i.v. injections of the mast cell activator compound 48/80, substance P, and capsaicin. The morphological effects of substance P and capsaicin on connective tissue mast cells in vivo were also examined. Of the drugs tested, only compound 48/80 degranulated the connective tissue mast cells. All drugs induced a subepithelial plasma exudation in the subglottic region, with edema in the lamina propria and widened intraepithelial intercellular spaces, though the tight junction regions seemed intact. In the epiglottis, 10 min after compound 48/80 injection, there was edema in the lamina propria on the lingual side, with an intact and tight epithelial lining. No morphological sign of edema was found in the epiglottis after injection of substance P or capsaicin. The pronounced effect found in the epiglottic region after compound 48/80 injection was due to the release of mediators such as histamine and 5-hydroxytryptamine from the connective tissue mast cells. This study supports the belief that substance P in vivo mediates an increased vascular permeability by a direct effect on the blood vessels – a mechanism distinct from mast cell degranulation.     

Neurotensin elevates hematocrit and plasma levels of the leukotrienes, LTB4, LTC4, LTD4 and LTE4, in anesthetized rats.

The IV injection of neurotensin (NT) into anesthetized rats produced a marked increase in hematocrit, labored breathing and peripheral blood stasis with cyanosis. This effect could also be produced by the NT-related peptides, neuromedin-N and xenopsin; however, it was not observed when nine other biologically active peptides, including bradykinin and substance P, were tested. Associated with these responses were increases in the plasma levels of histamine (measured radioenzymatically) and the leukotrienes, LTB4, LTC4, LTD4, and LTE4 (measured by RIA and HPLC). The increment in hematocrit after varying doses of NT correlated to the increase in plasma levels of LTC4. Histamine and LTC4 were both capable of elevating hematocrit when given IV; however, LTC4 was approximately 1000 times more potent than histamine and active doses of histamine elevated LTC4 levels. Furthermore, the effects of NT on plasma LTC4 and hematocrit were reduced by pretreating animals with antagonists to histamine and serotonin. Pretreatment with the specific mast cell degranulating agent, compound 48/80, also blocked NT's ability to elevate plasma levels of histamine, LTB4 and LTC4 and prevented the increased hematocrit and cyanosis. These results indicate that NT-related peptides are very potent and specific stimulators of leukotriene release and that this action is mediated by mast cells and associated with loss of plasma volume and blood stasis. A working hypothesis is that histamine, released from mast cells in response to NT, stimulates LTC4 production by other cells.     

Uterine autonomic nerve innervation plays a crucial role in regulating rat uterine mast cell functions during embryo implantation

To explore the potential mechanism of how uterine innervations would affect the uterine mast cell (MC) population and functions during the periimplantation. We herein first examined the consequence of uterine neurectomy on embryo implantation events. We observed that amputation of autonomic nerves innervating the uterus led to on-time implantation failure in rats. Exploiting MC culture and ELISA approaches, we then further analyzed the effect of neurectomy on cellular histamine levels and its release from uterine MCs, to elucidate the relation of the autonomic nerves and local cellular immunity in the uterine during early pregnancy. We observed that disconnection of autonomic nerve innervation significantly increased the population of uterine MCs. Most interestingly, these increased number of uterine MCs in neuroectomized rats contained a much reduced cellular level of histamine. Our subsequent challenge experiments revealed that uterine MCs in nerve amputated rats exhibited enhanced histamine releasing rate in response to substance P and antiIgE, suggesting loss of nerve innervation in the uterus not only increases the population of uterine MCs, but also facilitates the release of histamine from MCs, thus subsequently interfere with the normal implantation process. Collectively, our findings provide a new line of evidence supporting the concept that immune–neuro-endocrine network plays important role during pregnancy establishment and maintenance.     

Analysis of the mechanism of histamine release induced by substance P

Substance P causes release of histamine from rat peritoneal mast cells; the structure-activity relationship shows that N-terminal residue is essential and the hydrophobic region of C-terminal plays an important role. Electrical conductivity of black lipid membrane containing phosphatidic acid was augmented by substance P. In this case, N-terminal residues and C-terminal hydrophobicity were also unavoidable. The partitioning of substance P into the organic phase increased in the presence of phosphatidic acid. The CD spectrum of substance P was changed from the unordered form to beta-form by coexistence of phosphatidic acid/PC liposomes in the medium. The addition of calcium or magnesium in the test solution is effective to prevent either of these phenomena. These findings indicate that substance P probably binds to negatively charged sites of membrane lipids, and subsequent penetration of C-terminal into the hydrophobic core of lipid bilayer may induce an increase of membrane permeability and the following histamine release.     

The effects of substance P, histamine and histamine antagonists on somatostatin and gastrin release from the isolated perfused rat stomach

Secretion of somatostatin-like immunoreactivity (SLI) from the isolated perfused rat stomach has been shown to be inhibited by substance P. The present study was initiated to examine the possibility that this action of substance P was mediated via release of histamine. Substance P (1 microM) reduced basal secretion of SLI in agreement with earlier studies. Neither pyrilamine nor cimetidine influenced this action. Basal immunoreactive gastrin (IRG) secretion was unaffected by substance P. Addition of pyrilamine during substance P perfusion increased IRG secretion whereas addition of cimetidine resulted in a delayed decrease on removal of both compounds. Histamine (1 and 10 microM) increased SLI secretion and reduced IRG secretion. Pyrilamine increased and cimetidine decreased IRG secretion but neither drug influenced SLI secretion. Pyrilamine had no effect on histamine-stimulated SLI secretion but inhibition of IRG secretion by histamine was converted to stimulation. Cimetidine potentiated histamine stimulation of SLI secretion and inhibition of IRG secretion. In conclusion: (1) substance P inhibition of SLI secretion is unlikely to be mediated via release of histamine. (2) The gastrin cell appears to have both H1- and H2-receptors which mediate opposite actions but H1-receptor-mediated inhibition is predominant. (3) Histamine weakly stimulates SLI secretion but there may be both inhibitory and stimulatory pathways acting via H2- and H1-receptors, respectively.     

Effect of estrogen on the response of thyroid stimulating hormone to substance P in rats

The role of substance P (SP) in the control of thyroid stimulating hormone (TSH) release and the influence of gonadal steroid were investigated. Intravenous administration of SP failed to alter plasma levels of TSH in ovariectomized (OVX) rats, whereas SP induced a significant increase in plasma TSH in estradiol benzoate-primed (Eb-primed) OVX rats (P less than 0.001). Further, intravenously administered SP did not affect the plasma TSH concentration in normal male rats, but significantly increased it in Eb-primed castrated male rats (P less than 0.01). These data suggest possible roles for SP at the level of the hypothalamus and/or the pituitary gland in stimulating TSH secretion under the influence of estrogen.     

R?le of histamine on plasma fibrinogen levels in rats with surgical injury (laparotomy)

The probable r?le of endogenous histamine in the increase of plasma fibrinogen in rats submitted to tissue injury (laparotomy) was studied. In laparotomized rats with 10 mg kg-1 day-1 of diphenhydramine (a H1-histamine receptor blocker) plasma fibrinogen decreased significantly as compared to the group of rats laparotomized only (P less than 0.02), reaching values similar to those observed in rats laparotomized with removal of the adrenal medulla or laparotomized with severing of splanchnic nerves. There is a significant difference between these latter groups and the normal noninjured group (P less than 0.01). Plasma fibrinogen did not modify (as compared with the uninjured group) in rats injected only with histamine (1 mg kg-1 day-1) or with diphenhydramine. Taking into account the results obtained and the mechanism of action of diphenhydramine, it would seen that endogenous histamine takes part in the increase of plasma fibrinogen in laparotomized rats, perhaps indirectly through stimulation of the adrenal medulla secretion.     

Effect of the ET(B) receptor agonist, IRL-1620, on paclitaxel plasma pharmacokinetics of breast tumor rats

Endothelin (ET)-B receptors are expressed in human breast carcinoma. We previously demonstrated that intravenous administration of the ET(B) receptor agonist, IRL-1620, to tumor-bearing rats, increased blood perfusion and enhanced delivery of paclitaxel to breast tumor tissue. The present study was conducted to determine whether IRL-1620 alters the pharmacokinetics of paclitaxel. Breast tumor-bearing rats were given 0.3 ml/kg saline or 3 nmol/kg IRL-1620 by intravenous (iv) administration. Fifteen minutes after saline or IRL-1620, 40 microCi/rat 3H-Paclitaxel was administered iv and serial plasma samples were collected until 24 hrs. 3H-Paclitaxel radioactivity in the plasma samples was measured by liquid scintillation counting. Data were fit to a three-compartment model and pharmacokinetic parameters were generated using WinNonlin software. IRL-1620 did not produce any change in the plasma paclitaxel pharmacokinetics of tumor-bearing rats. The AUC(0-infinity) (9.43 +/- 3.18 microg-hr/ml), clearance (0.69 +/- 0.17 l/hr/kg), volume of distribution (10.31 +/- 4.54 l/kg), and half-life (1.0 +/- 0.32 hrs) of paclitaxel were similar between rats treated with saline or IRL-1620. In conclusion, the ET(B) receptor agonist, IRL-1620, does not alter paclitaxel plasma pharmacokinetics and, therefore, could be used to augment the delivery of paclitaxel to the tumor tissue.     

Changes in blood histamine and bradykininogen levels during different periods of the oestrous cycle in goats.

Blood histamine and plasma bradykininogen levels were estimated in eighteen normally cyclic goats at different periods of the oestrous cycle. The histamine level increased significantly (P smaller than 0.05) on Day 18 of the oestrous cycle. The bradykininogen level decreased significantly (P smaller than 0.05) towards the end of oestrus.     

Influenza infection causes airway hyperresponsiveness by decreasing enkephalinase

Ferret tracheal segments were infected with human influenza virus A/Taiwan/86 (H1N1) in vitro. After 4 days, the smooth muscle contractile responses to acetylcholine and to substance P were measured. The response to substance P was markedly accentuated, with a threefold increase in force of contraction at a substance P concentration of 10(-5) M, the highest concentration tested. In contrast, the response to acetylcholine was not affected by viral infection. Histological examination of tissues revealed extensive epithelial desquamation. Activity of enkephalinase (neutral metallo-endopeptidase, EC.3.4.24.11), an enzyme that degrades substance P, was decreased by 50% in infected tissues. Inhibiting enkephalinase activity by pretreating with thiorphan (10(-5) M) increased the response to substance P to the same final level in both infected and control tissues. Inhibiting other substance P-degrading enzymes including kininase II (angiotensin-converting enzyme), serine proteases, and aminopeptidases did not affect the response to substance P. Inhibiting cyclooxygenase and lipoxygenase activity using indomethacin and BW 755c did not affect hyperresponsiveness to substance P. Pretreating tissues with antagonists of alpha-adrenoceptors, beta-adrenoceptors, and H1 histamine receptors (phentolamine 10(-5) M, propranolol 5 X 10(-6) M, and pyrilamine 10(-5) M, respectively) had no effect on substance P-induced contraction. These results demonstrate that infection of ferret airway tissues with influenza virus increases the contractile response of airway smooth muscle to substance P. This effect is caused by decreased enkephalinase activity in infected tissues.     

Modulation of serum cortisol by substance P in albino rats: evidence of a direct effect on adrenal gland

Effect of prolonged administration of substance P on the plasma cortisol level in the albino rats has been investigated. An inhibitory impact on intact individuals and a stimulatory effect in pharmacologically annulled rats has been observed. It is concluded that in normal conditions substance P presumably acts as a preventive agent for any excess secretion of cortisol while during stress or disturbed HPA or RAS conditions, it stimulates the secretion of cortisol. An intraglandular modulatory role of substance P has been suggested.     

Morphological and functional characteristics of peritoneal mast cells from young rats

To study why neonatal and young rats are resistant to the effects of some secretagogues, such as compound 48/80 and 2.5-S nerve growth factor, we examined peritoneal mast cells from 14–15-day-old rats (young rats) and compared them to peritoneal mast cells from adults. Peritoneal mast cells from young rats contain approximately one-tenth of the amount of histamine observed in adult peritoneal mast cells. However, both cell populations contained similar low levels of the mucosal mast cell-associated protease rat mast cell protease II. Histochemical analysis of peritoneal mast cells from young rats using safranin O and berberine sulphate suggested that only a portion of the granules of these cells contained heparin. At an ultrastructural level the young rat peritoneal mast cell contains relatively few granules. The majority of mast cells from young rats have a bilobed or indented nucleus which is only rarely observed in adult cells. Functionally, the young rat peritoneal mast cell demonstrates a significantly reduced histamine release in response to the connective tissue mast cellspecific secretagogues compound 48/80 and 2.5-S nerve growth factor. In contrast, the percent histamine release in response to the neurotransmitter substance P, which degranulates both connective tissue mast cells and intestinal mucosal mast cells, was similar in the adult cells and the young rat cells. This study demonstrates substantial differences between the young rat and adult peritoneal mast cells which may explain the ability of very young animals to withstand large doses of certain secretagogues.     

Acute effect of substance P in immunologic vasculitis in the rat colon

Substance P has been implicated as a neuronal mediator of inflammation in various inflammatory conditions. However, the exact role played by substance P in inflammatory bowel diseases or in experimental colonic vasculitis has not been clearly understood. In this study, we examined the effect of close superior mesenteric artery injection of substance P under prevailing inflammatory conditions induced by intravenous human albumin antialbumin immune complex followed by intracolonic perfusion of 2.5% formaldehyde in rats or intracolonic perfusion of 5% alcohol alone. The immune complex- and formaldehyde-treated rats showed severe microvascular changes such as microvascular plugging by red blood cells, endothelial breakage and extravasation of plasma proteins and red blood cells. The bolus injection of 10⁻⁸ M substance P reduced extravasation of Evans blue dye by 50% and the tissue wet to dry ratio by 20% in immune complex- and formaldehyde-perfused rats. Myeloperoxidase activity was not changed. Substance P also significantly inhibited (44%) the extravasation in alcohol-perfused rats. Pretreatment of immune complex- and formaldehyde-treated rats with substance P antagonist reversed the effect of substance P. These findings suggest that the most immediate effect of substance P may be vasodilation and clearing of vascular plugs induced by immune complex and formaldehyde. This effect of substance P differs from its chronic effect, which causes vasodilation and extravasation.     

Effect of substance P on catecholamine levels in the hypothalamus and midbrain in the rat during immobilization stress

Single intraperitoneal injection of substance P in a dose of 125 mcg/kg induced a significant increase of noradrenaline and dopamine level in the hypothalamus and the midbrain of intact rats. Under conditions of immobilization emotional stress, the substance P eliminated the stress induced decrease of hypothalamic noradrenaline and increase of its level in the midbrain; in other words the substance P normalized the noradrenaline level. Modulatory effect of a single injection of the substance P had a long-term character and was synchronized with an earlier found increase of resistability of rats to chronic emotional stress.     

Changes in the Metabolism of Histamine arid Monoamines After Occlusion of the Middle Cerebral Artery in Rats

Changes in the levels of histamine, monoamines, and their metabolites in the cerebral cortex and striatum after occlusion of the middle cerebral artery in rats were examined. The water content of the ipsilateral brain regions gradually increased after occlusion. In the ischemic side, 1 h after occlusion, the cortical norepinephrine and striatal 5-hydroxy-tryptamine levels significantly decreased, and striatal 3,4-dihydroxyphenylacetic acid and homovanillic acid levels markedly increased. In contrast, the levels of histamine and tele-methylhistamine in either brain region gradually increased and the changes became pronounced and statistically significant 6-12 h after induction of ischemia. The striatal histamine and tele-methylhistamine reached levels three- and twofold higher, respectively, than those of the contralateral side. In rats treated with alpha-fluoromethylhistidine 1 h before induction of ischemia, elevation of histamine and tele-methylhistamine was not observed. The elevated histamine level in the ipsilateral straitum at 9 h after occlusion was further significantly increased by the treatment with metoprine, an inhibitor of histamine-N-methyltransferase. These results suggest that the histaminergic activity in the brain is gradually enhanced by cerebral ischemia.     

Impaired responsiveness of renal sensory nerves in streptozotocin-treated rats and obese Zucker diabetic fatty rats: role of angiotensin

Increasing afferent renal nerve activity decreases efferent renal nerve activity and increases urinary sodium excretion. Activation of renal pelvic mechanosensory nerves is impaired in streptozotocin (STZ)-treated rats (model of type 1 diabetes). Decreased activation of renal sensory nerves would lead to increased efferent renal nerve activity, sodium retention, and hypertension. We examined whether the reduced activation of renal sensory nerves in STZ rats was due to increased renal angiotensin activity and whether activation of the renal sensory nerves was impaired in obese Zucker diabetic fatty (ZDF) rats (model of type 2 diabetes). In an isolated renal pelvic wall preparation from rats treated with STZ for 2 wk, PGE2 failed to increase the release of substance P, from 5 +/- 1 to 6 +/- 1 pg/min. In pelvises from sham STZ rats, PGE2 increased substance P release from 6 +/- 1 to 13 +/- 2 pg/min. Adding losartan to the incubation bath increased PGE2-mediated release of substance P in STZ rats, from 5 +/- 1 to 10 +/- 2 pg/min, but had no effect in sham STZ rats. In pelvises from obese ZDF rats (22-46 wk old), PGE2 increased substance P release from 12.0 +/- 1.2 to 18.3 +/- 1.2 pg/min, which was less than that from lean ZDF rats (10.3 +/- 1.6 to 22.5 +/- 2.4 pg/min). Losartan had no effect on the PGE2-mediated substance P release in obese or lean ZDF rats. We conclude that the mechanisms involved in the decreased responsiveness of the renal sensory nerves in STZ rats involve activation of the renin angiotensin system in STZ but not in obese ZDF rats.     

Effects of histamine and cimetidine on the levels of serotonin and 5-hydroxyindoleacetic acid in various parts of the digestive tract and in the blood and brain of rats

In the investigations on male Wistar rats it was demonstrated that histamine (0.05 and 0.5 mg/kg) decreased the serotonin level, without affecting the level of 5-HIAA in the stomach and duodenum. Contrary to this, cimetidine (15, 75 and 150 mg/kg) raised slightly the level of serotonin and decreased the 5-HIAA level in the stomach and duodenum. In the jejunum histamine in the lower dose raised the levels of serotonin and 5-HIAA, and in the higher dose it decreased only the concentration of serotonin. Cimetidine, on the other hand, only in the highest dose increased the serotonin level and decreased significantly the level of 5-HIAA. In the brain a rise of the serotonin level was observed only after histamine. No effects were observed of histamine and cimetidine on the blood serotonin level. Histamine reduced the number of enterochromaffinocytes in the duodenum. These results point to an evident interaction between the histaminergic and the serotoninergic structures in the digestive tract of rats.     

Effect of handling of plasma samples on histamine radio-enzyme assay

1. Freeze-thawing of plasma samples increased the histamine level at physiological histamine concentrations as analyzed by radio-enzyme assay, but not by high performance liquid chromatography. 2. Heating of plasma samples decreased the histamine levels. 3. Enzymatic or non-enzymatic formation of histamine during handling of plasma samples was not detected. 4. Some albumin preparations contain histamine.     

即刻电针介入对IBS模型大鼠血浆ET,CGRP水平及结肠ETR-A,CGRPmRNA表达的影响

目的：比较即刻电针天枢穴、足三里穴对肠易激综合征（ms）模型大鼠血浆降钙基因相关肽（CGRP）、内皮素（ET）水平及结肠组织中内皮素受体A（ETR－A）、CGRPmRNA表达的影响,旨在探讨电针即刻治疗IBS的部分机制。方法：采用WISTAR幼鼠制备肠易激综合征模型,随机分为空白对照组、模型组、天枢组、足三里组,每组8只。空白对照组不作任何处理,模型组只束缚不针刺,天枢组和足三里组在实验第8周电针治疗一次,留针20min。治疗结束后处死大鼠,取大鼠血浆及部分结肠组织进行生物活性物质检测。采用酶联免疫法检测血浆中CGRP、ET、结肠组织中ETR—A的含量,采用RT—PCR法检测结肠组织中CGRPmRNA表达。结果：（1）即刻电针对IBS模型大鼠血浆CGRP、ET水平的影响：与空白对照组比较,模型组CGRP水平明显降低（P〈0．01）;与模型组比较,天枢组、足三里组CGRP水平明显升高（P〈0．01）。与空白对照组比较,模型组ET水平升高（P〈0．05）;与模型组比较,天枢组ET水平明显降低（P〈0．01）。（2）即刻电针对IBS模型大鼠结肠组织ETR—A水平的影响：与空白对照组比较,模型组ETR—A水平明显升高（P〈0．01）;与模型组比较,足三里组ETR-A水平明显降低（P〈0．01）。（3）即刻电针对IBS模型大鼠结肠组织CGRPmRNA表达的影响：与空白对照组比较,模型组、天枢组、足三里组CGRPmRNA表达明显增强（P〈0．01,P〈0．05）;与模型组比较,足三里组CGRPmRNA表达减弱（P〈0．05）。结论：即刻电针介入后,能够调节机体的内环境紊乱和CGRP、ET的平衡失调。这种调节作用因穴位不同而具有不同的特点,天枢穴对血浆中CGRP、ET调节作用较强,足三里穴在受体和基因表达方面作用明显。     

Inhibition by dexamethasone of histamine production in allergic inflammation in rats.

In an allergic inflammation model of air pouch type in rats, histamine level in the pouch fluid and histidine decarboxylase activity of pouch wall tissues in the postanaphylaxis phase were increased. Although treatment with dexamethasone failed to inhibit histamine release from mast cells in the anaphylaxis phase, histamine production in the postanaphylaxis phase was inhibited dose dependently. Histamine production-increasing activity in the pouch fluid collected 8 h after the Ag challenge, which was estimated by an activity to stimulate histamine production by bone marrow cells, was decreased by the administration of dexamethasone at the time of the Ag challenge. The addition of steroidal antiinflammatory drugs, dexamethasone, prednisolone, or hydrocortisone, into the incubation medium inhibited the pouch fluid-induced histamine production by bone marrow cells. Hydrocortisone mesylate antagonized the inhibitory effect of dexamethasone on histamine production by bone marrow cells. However, hydrocortisone mesylate failed to recover the decrease in histamine production-increasing activity of the pouch fluid collected from dexamethasone-treated rats. In addition, the dialyzed sample of pouch fluid obtained from dexamethasone-treated nonsensitized rats did not reduce the stimulated histamine production by the pouch fluid sample obtained from the sensitized rats. However, increase in histamine production of bone marrow cells stimulated by the pouch fluid was not inhibited by cyclosporin A that inhibited histamine production induced by Con A. This observation indicates that the pouch fluid has no effect to induce production of the histamine production-increasing factor by bone marrow cells. Consequently, it is suggested that dexamethasone inhibits not only the production of histamine production-increasing factor but also the response of histamine-producing cells to this factor.