Lysophosphatidylserine as histamine releaser in mice and rats

Lysophosphatidylserine is a specific inducer of histamine release in isolated mast cells. To determine whether a similar effect is manifest in vivo, the phospholipid was injected (1-5 mg/kg i.v.) into mice and rats. A dose-dependent rise in blood histamine was observed in both animals. The several-fold increase in blood histamine occurred in the first minutes and was followed by a slower decline toward normal values. A second dose of lysophosphatidylserine was without effect. Systemic manifestations (depression, hypothermia, hypotension) were associated with the increased blood histamine level. When the tissue histamine stores accessible to lysophosphatidylserine were previously decreased by repeated phospholipid injections, no systemic symptoms occurred. Mobilization of carbohydrate reserves was also manifest during the action of lysophosphatidylserine. Prior treatment with compound 48/80 induced sustained refractoriness to lysophosphatidylserine. Structure-activity relationship demonstrated that the property to induce histamine release was linked to the structure of serine head group. Thus, other natural phospholipids or lysophospholipids were inactive. It is concluded that in analogy with the effect seen in vitro lysophosphatidylserine produces in vivo release of mast cell histamine.     

Blood histamine levels and arteriovenous concentration differences after the intravenous administration of the basic compounds l-3 and 48/80 in the anaesthetized dog.

The effects of the i.v. administration of inulin trinicotinate-monomethochloride (L-3) on haemodynamics, airway pressure and blood histamine levels were studied in chloralose-anaesthetized dogs and compared with the effects of compound 48/80. The control arterial histamine level was 0.041 plus or minus 0.002 mug/ml (mean plus or minus SEM) as determined by a fluorometric assay. L-3 (0.15 mg/kg) released high amounts of histamine, as indicated by a peak level in arterial histamine of 0.212 plus or minus 0.027 mug/ml within 3 min, which was not futher enhanced on increasing the dosage of L-3 to 1 mg/kg. After the i.v. injection of 0.15 mg/kg of 48/80 the peak level in arterial histamine was 0.146 plus or minus 0.008 mug/ml, and the level was further markedly elevated to 0.918 plus or minus 0.068 mug/ml after the administration of 1 mg/kg of 48/80. The concomitant fall in systemic blood pressure and the rise in airway pressure can be satisfactorily explained on the basis of histamine liberation. Whereas these parameters as well as the blood histamine concentration gradually returned to control values, the heart rate remained elevated during the observation period of 2 h. The arteriovenous differences in blood histamine across various tissues and organs following L-3 and 48/80 administration indicated histamine release mainly from skin and muscle and histamine uptake by the kidney, the digestive tract and to a lesser extent the lungs. The portal-hepatic vein differences revealed no consistent changes in liver histamine balance. As regards the lungs and liver, the present results suggest a dynamic equilibrium between histamine release and uptake in these organs in the intact animal. Both, L-3 and 48/80 elicited a similar pattern of histamine release and uptake. The extreme histamine releasing capacity of 1 mg/kg of 48/80 may be explained by an additional non-selective mechanism of histamine liberation.     

Biphasic blood pressure response to neuropeptide Y in anesthetized rats

The effects of neuropeptide Y (NPY) on systemic arterial blood pressure and heart rate were studied in anesthetized intact and pithed rats. I.v. doses of NPY (0.3-30 nmol/kg) raised the mean arterial blood pressure dose dependently. At doses of greater than or equal to 3.0 nmol/kg, the initial pressor response was followed by a dose-dependent fall in blood pressure in intact and pithed rats. The depressor response was accompanied 1-2 min after the NPY injection by a slight increase in heart rate in pithed rats but not in intact rats, and 10 min after the injection by a decrease in heart rate in intact rats. After repeated injections of NPY, the depressor effect vanished, whereas the integrated pressor response over time was markedly enhanced. After pretreatment with the histamine H1-receptor antagonist, mepyramine, or with the histamine liberator, compound 48/80, the pressor response to NPY remained but the depressor response disappeared. We suggest that the marked fall in blood pressure can be attributed to NPY-evoked histamine release from mast cells.     

Lack of histamine involvement in parathyroid hormone hypotensive action

Promethazine and cimetidine blocked the hypotensive actions of 2-pyridylethylamine, and H1 agonist and dimaprit, an H2 agonist, respectively, but not that of bovine parathyroid hormone fragment [bPTH-(1-34)]. Rats were treated repeatedly with the histamine releaser, compound 48/80, until the release could no longer produce a decrease in blood pressure. The hypotensive action of bPTH-(1-34) could still be seen. Rats with histamine partially depleted with one injection of compound 48/80 were injected with cimetidine and pyrilamine, and H1 antagonist, which together blocked the hypotensive action of subsequent injections of compound 48/80, but not that of bPTH-(1-34). These data suggest that the vasodilatory action of bPTH-(1-34) does not involve the release or action of histamine.     

Role of endogenous serotonin and histamine in the pathogenesis of gastric mucosal lesions in unanaesthetised rats with a single treatment of compound 48/80, a mast cell degranulator.

In unanaethetised rats with a single injection of compound 48/80, a mast cell degranulator (0.75 mg kg-1, i.p.), gastric lesions occurred with increased serum serotonin and histamine levels and reduced gastric mucosal blood flow at 0.5 h after the injection and developed at 3 h. Pretreatment with either cyproheptadine (a serotonin and histamine antagonist) or methysergide (a serotonin antagonist) prevented the formation of gastric mucosal lesions with attenuation of reduced gastric mucosal blood flow at 0.5 h after compound 48/80 injection, while pretreatment with either amitriptyline (a selective inhibitor of histamine release from mast cells), tripelennamine (a histamine H1-receptor antagonist), famotidine (a histamine H2-receptor antagonist) or cimetidine (a histamine H2-receptor antagonist) had no effect. Pretreatment with either cyproheptadine, methysergide, amitriptyline or tripelennamine prevented the development of gastric mucosal lesions at 3 h after compound 48/80 injection, while pretreatment with either famotidine or cimetidine had no effect. These results indicate that in unanaesthetised rats with a single compound 48/80 treatment, acutely released endogenous serotonin causes gastric mucosal lesions, while released endogenous histamine mainly contributes to the lesion development and that gastric acid plays little role in the pathogenesis of the compound 48/80-induced acute gastric lesions.     

Increase of plasma renin activity after subcutaneous application of compound 48/80 in the rat

Subcutaneous (s.c.) administration of compound 48/80 (3.0 mg/kg) to conscious rats produced a time-dependent long-lasting increase of plasma renin activity (PRA). A dose-related increase of the hematocrit was also observed after injection of compound 48/80. The onset of the hematocrit increase preceded that of PRA increase. Pretreatment with a dose of more than 20 mg/kg of histamine H1-receptor antagonists such as tripelennamine or diphenhydramine prior to the injection of compound 48/80 (3.0 mg/kg s.c.) attenuated or abolished the effects of compound 48/80 on PRA, hematocrit and plasma extravasation. Pretreatment with cimetidine (histamine H2-receptor antagonist, 40 mg/kg i.p.) had no effect on these plasma variables. The increase of PRA caused by s.c. administration of compound 48/80 was not affected by the pretreatment with propranolol (beta-adrenoceptor antagonist, 10 mg/kg i.p.), which completely inhibited the isoproterenol (0.5 mg/kg s.c.)-induced PRA increase. Administration of compound 48/80 did not induce a significant PRA increase in the nephrectomized rats although the increase of hematocrit following s.c. administration of compound 48/80 persisted despite the absence of kidneys. S.c. administration of compound 48/80 (3.0 mg/kg) led to a significant decrease of histamine content at the site of injection and to a significant increase in plasma histamine concentration without affecting arterial blood pressure. The present data suggest that s.c. administration of compound 48/80 stimulates the release of histamine from cutaneous mast cells, which cause an increase in vascular permeability to plasma protein via the stimulation of histamine H1-receptors, then leads to hypovolemia. The resulting hypovolemia may directly stimulate the juxtraglomerular cells of the kidney to release renin.     

A method for determining whether hypotension caused by novel compounds in preclinical development results from histamine release

INTRODUCTION: Many therapeutic agents stimulate histamine release from mast cells, which results in a decrease in blood pressure. The purpose of this study is to establish a method to determine if the mechanism of action, or one of the mechanisms, of hypotensive compounds is related to the release of histamine. The method was developed using a novel hypotensive compound, SC-372. METHODS: In Inactin anesthetized rats, after intravenous administration of SC-372 (0.3-7 mg/kg), the 2 and 7 mg/kg resulted in a dose-dependent decrease in blood pressure. Histamine (0.1 and 1 mg/kg) was injected intravenously to establish whether histamine release was the mechanism of action for the hypotension induced by SC-372. Compound 48/80 (0.1 mg/kg, promotes histamine release) and Cromolyn (1 mg/kg/min, [5 min], prevents histamine release from mast cells) were characterized and used intravenously in combination with/or compared to SC-372. RESULTS: Histamine resulted in a decrease in blood pressure that was unaffected by Cromolyn (1 mg/kg). Administration of Compound 48/80 resulted in a rapid reduction of systemic blood pressure. Intravenous infusion of Cromolyn prior to the injection of Compound 48/80 significantly attentuated the hypotensive response and the increase in histamine levels in the plasma. Intravenous administration of SC-372 resulted in a rapid reduction in blood pressure with a profile similar to that of Compound 48/80. When the rats were treated with Cromolyn prior to the administration of SC-372, both the blood pressure and plasma histamine levels were maintained at their pretreatment control levels. DISCUSSION: These data indicate that Compound 48/80 and Cromolyn can be used in rats to screen for histamine release-dependent drug-induced hypotension and suggest that the rapid decrease in blood pressure caused by SC-372 may result from histamine release from mast cells.     

Edema formation and degranulation of mast cells by Trimeresurus mucrosquamatus snake venom

Trimeresurus mucrosquamatus venom, carrageenin, compound 48/80, trypsin and bovine serum albumin were injected s.c. into the plantar muscle to induce edema formation in the hind paw of rats. The venom was the most potent, and it and compound 48/80 induced the maximum swelling rate of edema within 15 - 30 min after injection. The edema volume induced by the venom was dose-dependent between 2.5 and 10 micrograms. Hydrocortisone, phenylbutazone, indomethacin and diphenhydramine inhibited edema induced by the venom and other inflammatory agents. Diphenhydramine was the most effective inhibitor of edema and increased vascular permeability induced by the venom. Injection of the venom i.p. caused exocytosis and degranulation of mesentery mast cells with a decreased electron density of released granules. Systemic administration of diphenhydramine inhibited the venom-induced exocytosis. Diphenhydramine and pyrilamine inhibited the contraction of guinea-pig ileum caused by venom or compound 48/80. It is concluded that histamine released from mast cells plays an important role in the causation of the edema induced by Trimeresurus mucrosquamatus snakebites.     

Norbinaltorphimine, a selective kappa-opioid receptor antagonist, induces an itch-associated response in mice

We examined the possibility that scratching induced by norbinaltorphimine, a selective kappa-opioid receptor antagonist, is due to an itch sensation, using compound 48/80 as control pruritogenic agent. When norbinaltorphimine was injected s.c. into the rostral back, mice scratched the skin around the injection site with their hind paws. Although the intensity of the scratching could not be compared because the dose and injection route were different, the character and time course of the scratching behavior induced by compound 48/80 injected i.d. were similar to those with norbinaltorphimine. The scratching behavior induced by norbinaltorphimine was dose-dependently and significantly inhibited by pretreatment with chlorpheniramine. Compound 48/80-induced scratching was also dose-dependently and significantly inhibited by p.o. pretreatment with chlorpheniramine. The scratching behavior induced by norbinaltorphimine was dose-dependently and significantly inhibited by pretreatment with U-50,488H (trans-(+/-)-2-(3,4-dichlorophenyl)-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl] acetamide methansulfonate), a kappa-opioid receptor agonist. Unexpectedly, the scratching behavior induced by compound 48/80 was also dose-dependently and significantly reduced by pretreatment with U-50,488H. These results suggest that the injection of norbinaltorphimine into the rostral back of the mouse elicited scratching, which may be an itch-associated response. Furthermore, the scratching behavior produced by norbinaltorphimine may be due in part to the release of histamine followed by antagonism of kappa-opioid receptors.     

Clearance of histamine from the peritoneal cavity of rats

To study the clearance of histamine from the peritoneal cavity of rats, histamine was either injected i.p. or released locally by the injection of compound 48/80. At various intervals peritoneal fluid was removed and analysed for histamine concentration by a fluorometric assay. Exogenous and endogenous histamine were cleared from the peritoneal cavity at the same rate with a half life of 20 minutes. The rate was not altered by different histamine concentrations, by injection of heparin, and by the removal of peritoneal leukocytes. Repeated injections of large amounts of histamine resulted in a decreased clearance. The results suggest that histamine concentrations above the physiological level are quickly degraded. Activities of histamine as an inflammatory mediator are likely to be of short duration.     

Comparison of histamine release from peritoneal mast cells derived from diabetic and control rats.

Clinical and experimental diabetes are associated with an increased number of mast cells and elevated tissue histamine concentrations. This study compared histamine release from peritoneal mast cells derived from diabetic and control rats. Experimental diabetes was induced by a single i.v. injection of streptozotocin (50 mg/kg body weight). Measurement of plasma glucose levels confirmed the diabetic state. Peritoneal mast cells were stimulated for 10 min with the lectin concanavalin A (0.5-100 micrograms/ml) in the presence or absence of phosphatidylserine, clinical dextran (0.6-1200 micrograms/ml) in the presence of phosphatidylserine, the calcium ionophore A23187 (0.1-1 microM) or the basic releasing agent compound 48/80 (0.1-10 micrograms/ml). Histamine release induced by these agents was similar in both populations. Further studies will compare the differences in histamine release from mast cells isolated from different tissues, e.g. heart and lung. In addition, physiological stimuli which are altered in the diabetic state (e.g. hyperosmolalar solutions and free radical generating systems) are under investigation.     

Circulatory depression and ventricular arrhythmias induced by compound 48/80 in anaesthetized rats.

The effects of graded doses of compound 48/80 on various cardiovascular and respiratory parameters were studied in pentobarbitone-anaesthetized rats. Following intravenous injections, this compound significantly depressed the mean blood pressure (MBP), left ventricular pressure (LVP) and dLVP/dtmax, and caused ventricular tachycardia (VT) or fibrillation (VF) and death. Heart rate (HR) response were variable, and there were no marked changes in airway resistance or blood gases. Pretreatment of the animals with either cimetidine or diphenhydramine significantly prolonged the time of onset of VT/VF but failed to alter the changes in other circulatory variables. A combination of cimetidine and diphenhydramine significantly alleviated the decreases in MBP and LVP and prevented the occurrence of VT/VF. It is suggested that the circulatory depression and the occurrence of ventricular arrhythmias following the administration of compound 48/80 result from activation of H1- and H2-receptors by elevated blood histamine levels due to release of the amine from tissues.     

Effect of nociceptin on histamine and serotonin release in the central nervous system

Role in pain sensation of both nociceptin (NC), the bioactive heptadecapeptide sequence of preproorphaninFQ and of histamine has been widely evidenced in the central nervous system (CNS). In the current series of experiments effect of intracerebroventricularly (i.c.v.) administered NC (5.5 nmol/rat) on histamine and serotonin levels in blood plasma, CSF and brain areas (hypothalamus and hippocampus) was studies and compared to the effect of the mast cell degranulator Compound 48/80(100microg/kg, i.c.v.) and the neuroactive peptide Substance P (50nmol/rat, i.c.v.). It was found that all the three compounds increased the histamine level in the CNS, however their activity concerning the mast cell-, and neuronal histamine release is different. NC could release histamine from both the mast cells and the neurons and it decreased CNS serotonin levels. Substance P was found the most potent in increasing CNS histamine levels. Compound 48/80 treatment resulted in elevated histamine levels both in the CNS and blood plasma. It is concluded that the histamine releasing effects of i.c.v. administered NC and SP are limited to the CNS, but in the effect of Compound 48/80 its blood-brain barrier impairing activity is also involved. Data also demonstrate that NC has significant effect on both the histaminergic and serotonergic neurotransmission in the CNS.     

Inhibitory effects of Moutan cortex on immediate allergic reactions

The anti-allergic effect of an ethanol extract from Moutan Cortex was evaluated in some animal models. The Moutan Cortex extract (30, 100 mg/kg, i.p.) dose-dependently inhibited systemic anaphylactic shock induced by compound 48/80 in mice. It also inhibited dose-dependently the scratching behavior induced by compound 48/80 or histamine at a dose of 100 mg/kg. An increase in the vascular permeability induced by compound 48/80 or histamine was also inhibited by the Moutan Cortex. In addition, in vitro studies, the Moutan Cortex inhibited histamine release from rat peritoneal mast cells induced by compound 48/80. To investigate the active component of Moutan Cortex extract, it was suspended in water and extracted with EtOAc to yield EtOAc insoluble (A) and soluble (B) fractions. The effect of extract (B) was more potent than that of extract (A) in inhibiting histamine release. From these findings, it seems likely that the Moutan Cortex extract is effective in antagonizing certain pharmacological effects induced by compound 48/80, which is probably mediated by inhibiting the release of histamine from mast cells and antagonizing the effect on histamine. The main active component of Moutan Cortex is considered to be contained in extract (B). In conclusion, Moutan Cortex may be useful for the relief of symptoms of atopic dermatitis and other allergy-related diseases.     

Comparison of histamine release induced by synthetic polycations with that by compound 48/80 from rat mast cells.

We compared the histamine release induced by polyethylenimines and polyallylamines with that induced by compound 48/80. Lidocaine inhibited the histamine release induced by polyethylenimine with a molecular weight of 600 (PEI6), but disodium cromoglycate did not. The histamine releases induced by all polyethylenimines and polyallylamines tested were inhibited by lidocaine, but not by disodium cromoglycate. Islet activating protein inhibited the histamine release induced by PEI6. Its effects on the release by other polyethylenimines and polyallylamines were less than that on PEI6. It is likely that the inhibition of G proteins by islet activating protein resulted in a decrease of the histamine release. This possibility was supported by the finding that guanyl-5'-(beta, gamma-imino) triphosphate enhanced the histamine release. An inhibitor of polyphosphoinositide phosphodiesterase, neomycin, did not affect the histamine releases induced by these polymers. The effect of PEI6 seemed to resemble that of compound 48/80. After pretreatment of mast cells with wheat germ agglutinin and with Limax flavus agglutinin, releases of histamine induced by PEI6 and compound 48/80 decreased, suggesting that the binding sites of PEI6 and compound 48/80 had sialic acid and/or N-acetyl glucosamine residues. The binding site for PEI6 seemed to especially overlap those of compound 48/80.     

The role of histamine in the acute inflammatory responses to intradermal platelet activating factor.

1. The role of histamine in PAF-induced acute inflammatory responses (flare and weal) in the skin has been evaluated in a series of three separate studies. 2. Terfenadine, a potent H1-selective histamine antagonist virtually abolished the flare response and significantly inhibited the weal response. 3. Histamine depletion in the skin using compound 48/80 resulted in similar effects on the flare and weal response. Two consecutive daily injections of compound 48/80 were found to deplete comprehensively skin sites of histamine and the ability of skin to respond to PAF was completely restored within 2 weeks of compound 48/80 treatment. 4. Intradermally injected PAF was associated with acute rises in plasma histamine in blood drawn from a draining vein with peak concentrations occurring within 5 min of injection. 5. No difference in PAF-induced flare and weal response was found between atopic and non-atopic subjects and this was reflected in the peak plasma histamine results. A significantly higher baseline plasma histamine was found in the atopic group, however, when compared with the non atopic group. 6. It is concluded that histamine has an important role in the acute inflammatory responses to intradermally injected PAF, although there does appear to be a significant direct vascular component in the PAF-induced weal response.     

Effect of Brazilian propolis on scratching behavior induced by compound 48/80 and histamine in mice

We studied the effect of Brazilian propolis on scratching behavior induced by compound 48/80 and histamine in ICR mice. Propolis granular A.P.C dose-related inhibited scratching behavior induced by compound 48/80 and significant inhibition were observed at 1000 mg/kg. However, histamine-induced scratching behavior was not inhibited by propolis granular A.P.C even at 1000 mg/kg. Propolis ethanol extract at 10 microg/ml or more inhibited histamine release from rat mast cells induced by compound 48/80. In addition, it blocked increased vascular permeability induced by compound 48/80. The inhibitory effect of propolis on scratching behavior induced by compound 48/80 was gradually enhanced by repeated administration, and 500 mg/kg propolis granular A.P.C, which caused no effect through single administration, significantly inhibited scratching behavior after repeated administration for 4 weeks. From these findings, it is assumed that the inhibition of scratching behavior induced by propolis occurs through a mast cell-dependent mechanism.     

Plasma histamine and catecholamine levels during hypotension induced by morphine and compound 48/80

Histamine receptors are present in adrenergic terminals, and histamine is reported to inhibit release of the neurotransmitter norepinephrine (NE) at certain neuroeffector junctions. However, a physiological role for histamine in modifying adrenergic neurotransmission has not been established. To examine the interaction of elevated plasma histamine and catecholamine release, two compounds that release histamine, morphine (3 mg/kg), and compound 48/80 (0.5 mg/kg), were administered intravenously (i.v.). Plasma norepinephrine (NE) levels were used to monitor sympathetic nervous system activity, and plasma epinephrine (Epi) levels were used to monitor adrenal activity. Both morphine and compound 48/80 caused an immediate and marked increase in plasma histamine. Simultaneous with this increase, a marked decrease in mean arterial pressure occurred. Plasma NE levels increased in animals administered compound 48/80, but in morphine-treated animals, plasma NE levels did not change from pretreatment values. Plasma Epi levels increased in both groups, but the magnitude and duration of the responses differed. The results indicate that elevated plasma catecholamines can increase in response to histamine-induced hypotension but this effect can be suppressed by the central actions of morphine.     

The utilization of adenosine triphosphate in rat mast cells during histamine release induced by anaphylactic reaction and compound 48/80

Summary The ATP content of rat peritoneal mast cells has been studied in relation to histamine release induced by compound 48/80 and antigen-antibody (anaphylactic) reaction in vitro. When the ATP content of actively sensitized mast cells was reduced to different levels by oligomycin, a good correlation was obtained between the ATP levels and the amounts of histamine released by the anaphylactic reaction. A similar linear relation has previously been demonstrated between the ATP levels of mast cells and histamine release induced by compound 48/80. The ATP content of mast cells was also studied at different intervals after the exposure of the cells to antigen or compound 48/80. No significant change in the ATP content was observed in untreated mast cells during the short period when histamine release occurs. If, however, the mast cells were preincubated with oligomycin or 2-deoxyglucose to reduce the rate of ATP synthesis while a large part of the histamine release remained unaffected—a decrease in the ATP content could be demonstrated in close time relation to both anaphylactic and compound 48/80-induced histamine release. The observations indicate an increased utilization of ATP in mast cells during the release process.     

The hypotensive effect of centrally administered neutrotensin in rats

We have evaluated the cardiovascular effects of intracerebroventricular (i.c.v.) injections of neurotensin (NT) in pentobarbital-anesthetized rats. In most animals, the i.c.v. injection of NT (5.4, 10.8 and 16.2 nmol/rat) induced a dose-dependent fall of the arterial blood pressure. This effect was usually rapid in onset (30–60 sec) and of short duration (～1–4 min). It was not preceded nor accompanied by any significant alteration of the heart rate. In about 25% of the animals, the vasodepressor effect of i.c.v. injections of NT was long lasting (30–45 min). Conscious rats were much less sensitive than anethetized animals. The hypotensive effects of intravenously (i.v.) administered NT was fully maintained in animals made tolerant to the hypotensive effect of centrally administered NT. Similarly, the animals made unresponsive to i.v. injections of NT either by repeated i.v. injections of NT (e.g. tachyphylaxis) or by a chronic treatment with compound 48/80, still responded normally to centrally administered NT. The results suggest the existence of at least two anatomically distinct sites of action through which NT can induce hypotension in rats. One appears to be located in the periphery and the other, in the central nervous system.