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At least 19 recordsLinked to original sources
PubMed1990

Anti-inflammatory activity of bee venom peptide 401 (mast cell degranulating peptide) and compound 48/80 results from mast cell degranulation in vivo.

1. The relationship between the anti-inflammatory activity of the bee venom peptide 401 in the carrageenin-induced oedema of the rat hind paw and its mast cell degranulating activity has been reinvestigated. 2. Mast cell degranulation caused by compound 48/80 (10 mg kg-1) or by allergen challenge in rats sensitized to Nippostrongylus brasiliensis also suppressed rat hind paw oedema in the same test. 3. The anti-inflammatory activities of peptide 401 and compound 48/80 were partially suppressed by pretreatment of rats with mepyramine and methysergide, at doses (2.5 mg kg-1) that completely suppressed skin reactions to these mast cell-derived amines. Pretreatment of rats with compound 48/80 also suppressed the apparent anti-inflammatory actions of peptide 401 and of compound 48/80. 4. Injection of peptide 401 together with carrageenin increased the inflammatory response in the rat hind paw. 5. The anti-inflammatory activity of peptide 401 and of compound 48/80 in the carrageenin-induced swelling of the rat hind paw arises from mast cell degranulation in vivo.

Allergens↗
PubMed1990

The role of mast cell degranulation products in mast cell hyperplasia. I. Mechanism of action of nerve growth factor.

A variety of mast cell degranulating agents have previously been shown to induce mast cell hyperplasia in adult rats. In neonates 2.5 S nerve growth factor (NGF) induces a hyperplasia of both mucosal and connective tissue mast cells (MMC and CTMC). We have examined the role of the potent mast cell degranulating properties of NGF on its ability to induce mast cell hyperplasia. Administration of NGF in combination with the mast cell stabilizing agent disodium cromoglycate was found to abrogate the CTMC hyperplasia induced by NGF alone. Treatment of neonatal rats with the alternate degranulating agent compound 48/80 was found to induce a limited CTMC but not a MMC hyperplasia. A supernatant obtained by degranulating purified adult rat peritoneal mast cells with anti-IgE was found to induce hyperplasia of the CTMC population similar to that observed with NGF administration. However, this degranulation product supernatant only induced a limited MMC hyperplasia as judged by RMCP II content of the tissues. These results suggest that NGF has dual action inducing mast cell hyperplasia; CTMC hyperplasia being dependent on the ability of NGF to degranulate mast cells. MMC hyperplasia induced by NGF is independent of CTMC degranulation. Degranulation products from peritoneal mast cells act to increase both MMC and CTMC populations in the neonate. These data suggest that the CTMC population may be regulated by an autocrine positive feedback mechanism in vivo.

Animals↗
PubMed1988

The receptor site for the bee venom mast cell degranulating peptide. Affinity labeling and evidence for a common molecular target for mast cell degranulating peptide and dendrotoxin I, a snake toxin active on K+ channels.

The mast cell degranulating peptide (MCD) and dendrotoxin I (DTXI) are two toxins, one extracted from bee venom, the other one from snake venom, that are thought to act on voltage-sensitive K+ channels. Binding sites for the two toxins have been solubilized. The solubilized sites were stable and retained their high affinity for 125I-DTXI and 125I-MCD (Kd approximately equal to 100 pM). Interactions were found between MCD and DTXI binding sites in the solubilized state, establishing that the two different toxins act on the same protein complex. This conclusion was strengthened by the observations (i) that conditions of solubilization that eliminated 125I-MCD binding activity also eliminated 125I-DTX binding activity while both types of activities were preserved in the presence of K+ or Rb+ and (ii) that binding components for the two types of toxins had similar sedimentation coefficients and copurified in partial purifications. A component of the receptor protein for 125I-MCD has been identified; it has a Mr of 77,000 +/- 2000. This polypeptide was similar to or identical in molecular weight with that which serves as a receptor for DTXI (Mr 76,000 +/- 2000).

Animals↗
PubMed1992

Relationship between mast cell degranulation and jejunal myoelectric alterations in intestinal anaphylaxis in rats.

The effects of two degranulators of mast cells and intestinal anaphylaxis on jejunal myoelectric activity were compared in rats fasted for 15 hours. Attempts to antagonize the motility changes were performed using antagonists of histamine and serotonin and a cyclooxygenase and lipoxygenase inhibitor. Hooded Lister rats were chronically fitted with electrodes implanted in the jejunal wall. A group of rats was sensitized to egg albumin and challenged 14 days later by intraduodenal infusion of antigen. Sensitized animals had serum titers greater than or equal to 1:64. The other group was administered with mast cells degranulators. Both 48/80 (1 mg/kg), a degranulator of connective mast cells, and bromolasalocid (2 mg/kg), acting on connective and mucosal mast cells, induced a phase of total spiking inhibition followed by a progressive irregular spiking activity until the recovery of migrating myoelectric complex pattern (about 3 hours after injection). In contrast, antigen challenge disrupted the migrating myoelectric complex pattern, which was replaced by a peculiar pattern characterized by propagated spike burst, lasting 98 +/- 11.3 minutes. Chlorpheniramine (1 mg/kg) antagonized only the inhibitory phase induced by degranulators and was ineffective on the intestinal anaphylaxis-induced motor changes. Methysergide (1 mg/kg) and indomethacin (5 mg/kg) significantly reduced the degranulator effects as well as the anaphylaxis-induced alterations of intestinal motility. It is concluded that anaphylaxis-induced motor disturbances are relevant to mucosal mast cell degranulation involving 5-hydroxytryptamine and arachidonic acid derivative products, whereas histamine release appears to be a minor component.

Anaphylaxis↗
PubMed1975

The initiation of mast cell degranulation: activation at the cell membrane.

The low molecular weight mast cell activator, polymyxin B, has been covalently bound to an insoluble matrix of Sepharose 4B. It has been demonstrated that mast cells in preparations of rat peritoneal cells bind to Sepharose 4B-polymyxin B beads but not to control beads. The bound cells are stimulated to degranulate by this interaction at the cell membrane with the resultant release of biogenic amines.

Animals↗
PubMed1992

Charybdotoxin, dendrotoxin and mast cell degranulating peptide block the voltage-activated K+ current of fibroblast cells stably transfected with NGK1 (Kv1.2) K+ channel complementary DNA.

The blocking actions of the K+ channel toxins charybdotoxin, dendrotoxin and mast cell degranulating peptide were studied in B82 mouse fibroblast cells transformed to express NGK1 (Kv1.2) K+ channels. All three toxins were potent blockers of the K+ current in these cells, with KD values of 1.7, 2.8 and 185 nM, respectively. The toxin block exhibited a weak voltage-dependence with the degree of inhibition decreasing at positive membrane potentials. For charybdotoxin and dendrotoxin, reducing [K+]i did not increase the fractional block, demonstrating that the relief of block at positive membrane potentials is not due to displacement of the toxin molecules by outward flow of K+ ions. A voltage-jump protocol was used to determine the rates of binding and unbinding of dendrotoxin and mast cell degranulating peptide; binding of charybdotoxin was too rapid to be quantitatively evaluated in this manner. The binding rates (dendrotoxin, approximately 5 x 10(7)/M per s; mast cell degranulating peptide, approximately 0.8 x 10(7)/M per s) were largely voltage-independent, suggesting that association of the toxin molecules with the channel is diffusion limited. The rates of unbinding (dendrotoxin, approximately 0.3/s; mast cell degranulating peptide, approximately 3/s at +60 mV) of both toxins increased e-fold per approximately 40 mV change in membrane potential, thus accounting for the voltage-dependence of the equilibrium block. Internal perfusion with the three toxins failed to affect the K+ current (in contrast to internal tetraethylammonium which strongly blocked the current), indicating that the toxins exert their blocking action by binding to extracellular sites.

Ampicillin Resistance↗
PubMed1991

Mast cell degranulation in hemorrhagic shock in rats and the effects of vasoactive intestinal peptide, aprotinin and H1 and H2-receptor blockers on degranulation.

Various stressful stimuli cause mast cell degranulation. Hemorrhagic shock is one such stressful stimulus which may cause mast cell degranulation and histamine release. Histamine may be involved in the pathophysiology of hemorrhage. It was reported that there are large amounts of histamine in the anterior and posterior lobes of the pituitary and the adjacent median eminence of the hypothalamus. Most of the histamine in the posterior pituitary is in mast cells. In addition, both vasoactive intestinal peptide (VIP) and histamine-containing neurons are available in the hypothalamus. It therefore seems reasonable to suppose that these three systems (i.e., mast cells, VIP-containing neurons, and histamine-containing neurons) may play an important role in the progression of hemorrhagic shock. 66 albino rats (200-250 g) of either sex were used. The presence of mast cells was examined by light microscopy. Hemorrhage caused mast cell degranulation in a correlation with the amount of blood loss. In all cases, the most intense degranulation was observed in the hypothalamus, especially the nucleus arcuatus, and in the subcutaneous tissue. The intensity of degranulation gradually decreased in the peripheral blood vessel, peritoneum and omentum, in this order. VIP prevented degranulation, but aprotinin and H1 and H2 receptor blockers did not.

Animals↗
PubMed1989

Edematous response caused by [Thi5,8,D-Phe7]bradykinin, a B2 receptor antagonist, is due to mast cell degranulation.

[Thi5,8,D-Phe7]bradykinin caused hind-paw edema and degranulation of isolated peritoneal mast cells in a dose-dependent manner. Pretreatment with diphenhydramine/methysergide or compound 48/80 completely suppressed the edematous response caused by [Thi5,8,D-Phe7]bradykinin, whereas bradykinin-induced hind-paw swelling was only partially inhibited by diphenhydramine and methysergide pretreatment; the residual response was significantly further depressed by [Thi5,8,D-Phe7]bradykinin. Neither the bradykinin- nor [Thi5,8,D-Phe7]bradykinin-induced edematous response was significantly affected by aspirin or BW755C. The mast cell degranulation caused by [Thi5,8,D-Phe7]bradykinin and bradykinin was inhibited by gangliosides but not by heparin. These results suggest that the edematous response elicited by [Thi5,8,D-Phe7]bradykinin was mainly due to the actions of mediators released by the degranulation of mast cells. Unlike bradykinin, [Thi5,8,D-Phe7]bradykinin was devoid of a direct exudation-promoting effect but exerted an antagonistic effect on the direct effect of kinin. If the influence of mast cells degranulation could be minimized, [Thi5,8,D-Phe7]bradykinin could be used as a tool to evaluate the role of kinin in the edematous response in inflammation.

Animals↗
PubMed1987

Mast cell degranulating peptide and dendrotoxin selectively inhibit a fast-activating potassium current and bind to common neuronal proteins.

Dendrotoxin and mast cell degranulating peptide are highly potent convulsant polypeptides from mamba snake and bee venoms, respectively. Electrophysiological techniques and binding assays were used to study their interaction with fast-activating, voltage-dependent potassium channels in rat neurons. Intracellular recordings in sensory ganglion cells showed that mast cell degranulating peptide blocks the same slowly inactivating potassium current as dendrotoxin but with lower potency, the respective IC50 values in sensory A neurons of nodose ganglion being 2.1 nM and 37 nM. In contrast, the transient potassium current (IA) in superior cervical ganglion neurons was unaffected by either toxin, highlighting the heterogeneity of these potassium channels and the selective action of the toxins. Using biologically active 125I-labelled derivatives of dendrotoxin and beta-bungarotoxin (a related snake protein), the binding of mast cell degranulating peptide to two subtypes of high-affinity acceptors in rat cerebrocortical synaptosomal preparations was examined. Mast cell degranulating peptide antagonized the specific binding of both radioiodinated toxins to each of the acceptor species, in the membrane-bound state; additionally, [125I]dendrotoxin binding in detergent-solubilized extracts was, likewise, blocked by mast cell degranulating peptide. Notably, the observed inhibitory constants (KI) for mast cell degranulating peptide were appreciably larger than for dendrotoxin, consistent with their different efficacies in blocking the potassium conductances. It is concluded that the specific interaction of this apian polypeptide with dendrotoxin acceptors must underlie its selective action on potassium conductances, emphasizing a functional relationship between these membrane acceptors and the potassium channel variants, sensitive to both dendrotoxin and mast cell degranulating peptide.

Action Potentials↗
PubMed1990

A further characterization of acridine-photosensitized inhibition of mast cell degranulation.

The purpose of this study was to further characterize acridine-photosensitized inhibition of mast cell degranulation. Acridine plus UVA radiation (320-400 nm) inhibited degranulation in response to antigen in IgE-sensitized rat serosal mast cells and in response to concanavalin A, which acts by a mechanism similar to antigen-IgE challenge. Removing oxygen from the incubation medium prevented the acridine-photosensitized inhibition of mast cell degranulation in response to 48/80. Acridine plus UVA radiation did not decrease mast cell ATP content, thus excluding inhibition of ATP production as a mechanism for photosensitized inhibition of mast cell degranulation. Although the viability of mast cells, as determined by uptake of trypan blue, was not affected 3 h after treatment with acridine plus UVA radiation, viability decreased by 6 h, and by 22 h 44% of the cells were nonviable. These results indicate that degranulation of mast cells by a variety of agents is inhibited by UVA plus acridine treatment, and that photosensitization requires oxygen and occurs before cytotoxicity.

Acridines↗
PubMed1990

Investigation of rat mast cell degranulation using flow cytometry.

Mast cells degranulation has been assessed by flow cytometry (FACS) taking advantage of the changes in the light scattering properties of mast cells stimulated by secretagogues. In turn, these changes are based on the modification of size, shape, and granule content of the cells before and after stimulation. With FACS, it is possible to work with almost pure mast cell populations (greater than 99%). Moreover, responses to compound 48/80 are carried out in real time and on the same cell sample that acts as internal control. This technique is very sensitive as shown by the ED50 of compound 48/80 (0.051 micrograms/mL) compared to its ED50 on histamine release (0.131 micrograms/mL). The well-known inhibitory effect of disodium cromoglycate against compound 48/80 was clearly observed using FACS. Furthermore, FACS allowed to distinguish between specific degranulating effects and cytotoxicity. Among the secretagogues used, only the degranulation induced by phospholipase A2 was inhibited by in vivo treatment with dexamethasone. It is suggested that the inhibitory effect is due to induction of phospholipase A2-inhibitory proteins (lipocortins).

Animals↗
PubMed1979

The effect of disodium cromoglycate on in vitro mast cell degranulation in human jejunal mucosa.

The in vitro effect of disodium cromoglycate (DSCG) on IgE antigen-induced mast cell degranulation is described. Serum from an egg white allergic patient was used to sensitize jejunal mucosa from nine individuals. Egg white was used to challenge the IgE sensitized mast cells. DSCG in concentrations 3 x 10(-7) M to 3 x 10(-4) M was added to the mucosal specimens before antigen challenge. Mast cell degranulation in the sensitized specimens challenged with egg white was 38%. Mast cell degranulation in sensitized specimens treated with DSCG before and during antigen challenge was reduced to 2% at a concentration of 3 x 10(-5) M of DSCG (P=0.006) and to 28% at a concentration of 3 x 10(-6) M (P=0.027). No significant reduction of mast cell degranulation was seen at concentrations of 3 x 10(-7) M and 3 x 10(-4) M. The results support a role for DSCG in the treatment of gastrointestinal allergy.

Antigens↗
PubMed1986

Elevated blood glucose after compound 48/80 treatment is not related to hepatic mast cell degranulation in rats.

Blood glucose, hepatic glycogen, and the histological integrity of hepatic mast cells, were evaluated in anesthetized rats receiving iv injections of 0.125 mg/kg body weight compound 48/80 (a mast cell degranulator) and/or of 0.001 to 10.0 mg/kg body weight lodoxamide tromethamine (an inhibitor of mast cell degranulation). A nonglucogenic dose of lodoxamide, 0.001 mg/kg body weight, prevented dissipation of histochemically demonstrable fluorescence in mast cells (degranulation) without inhibiting compound 48/80-induced hyperglycemia and hepatic glycogenolysis. These results suggest that this glucotropic response is independent of compound 48/80-evoked release of mediators such as serotonin from mast cells.

Animals↗
PubMed1989

Time course of human conjunctival mast cell degranulation in response to compound 48/80.

Compound 48/80, a non-immunogenic mast cell degranulatory agent, is known to produce the signs and symptoms of ocular allergy. Maximal mast cell degranulation of human conjunctiva occurred within the first hour after stimulation by a single topical dose of compound 48/80 (20 microliters, 7.5 mg/ml). The average percentage of fully degranulated mast cells in treated specimens (n = 9) was 31% (range 5-60%) versus 6% (range 0-20%) in control specimens (n = 5). Exact correlates of representative granulated, partially degranulated, and fully degranulated mast cells were determined by light and transmission electron microscopy.

Conjunctiva↗
PubMed1978

Mesenteric mast cell degranulation is not essential for conditioned taste aversion.

The possible role of mesenteric mast cell degranulation as the mediator of the initial UCS effects in the complex sequences leading to conditioned taste aversion (CTA) was studied. Both LiCl and Compound 48/80, a potent mast cell degranulator, produced CTA to 10% sucrose. Whereas the Compound 48/80 groups displayed massive mast cell degranulation, neither the LiCl treated nor saline control groups demonstrated any histologically determinable alterations. Administration of the antihistamine chlorpheniramine at dosages known to block radiation-induced CTA before the sucrose CS-UCS pairings did not block either LiCl- or Compound 48/80-induced CTA; the antihistamine actually facilitated the aversion. However, pretreatment with the antihistamine did not alter mesenteric mast cell morphology.

Animals↗
PubMed1978

[3H]serotonin release: an improved method to measure mast cell degranulation.

A method based on the release of tritium-labelled serotonin by activated mast cells in rodents is described. Mast cells incorporate labelled serotonin selectively and release the label after activation by non-specific stimulators (compound 48/80, polymyxin B sulphate, ATP, bovine chymotrypsin and L-alpha-lysophosphatidylcholine) or anaphylactic antibody and the corresponding antigen. These two types of activation were investigated in comparison with the toluidine blue microscopic rat mast cell degranulation test, and a methodological study of the release of [3H]serotonin is described. The measurement of labelled serotonin release provides a simple and quick assay of mast cell degranulation compared to the time required for the classical rat mast cell degranulation technique and achieves a greater sensitivity.

Animals↗