In vitro activation of murine DRG neurons by CGRP-mediated mucosal mast cell degranulation

Upregulation of CGRP-immunoreactive (IR) primary afferent nerve fibers accompanied by mastocytosis is characteristic for the Schistosoma mansoni-infected murine ileum. These mucosal mast cells (MMC) and CGRP-IR fibers, which originate from dorsal root (DRG) and nodose ganglia, are found in close apposition. We examined interactions between primary cultured MMC and CGRP-IR DRG neurons in vitro by confocal recording of intracellular Ca(2+) concentration ([Ca(2+)](i)). The degranulatory EC(50) for the mast cell secretagogue compound 48/80 (C48/80; 10 microg/ml) and the neuropeptides CGRP (2.10(-8) M) and substance P (SP; 3.10(-8) M) were determined by measurement of extracellular release of the granule chymase, mouse mast cell protease-1. Application of C48/80 (10 microg/ml) and CGRP and SP (both 10(-7) M) to Fluo-4-loaded MMC induced a transient rise in [Ca(2+)](i) after a lag time, indicative of mast cell degranulation and/or secretion. The CGRP response could be completely blocked by pertussis toxin (2 microg/ml), indicating involvement of G(i) proteins. Application of MMC juice, obtained by C48/80 degranulation of MMC, to Fluo-4-loaded DRG neurons induced in all neurons a rise in [Ca(2+)](i), indicative of activation. Degranulation of MMC by C48/80 in culture dishes containing Fluo-4-loaded DRG neurons also caused activation of the DRG neurons. In conclusion, these results demonstrate a bidirectional cross-talk between cultured MMC and CGRP-IR DRG neurons in vitro. This indicates that such a communication may be the functional relevance for the close apposition between MMC and CGRP-IR nerve fibers in vivo.     

Cannabinoid CB2 receptors in the enteric nervous system modulate gastrointestinal contractility in lipopolysaccharide-treated rats

Enhanced intestinal transit due to lipopolysaccharide (LPS) is reversed by cannabinoid (CB)2 receptor agonists in vivo, but the site and mechanism of action are unknown. We have tested the hypothesis that CB2 receptors are expressed in the enteric nervous system and are activated in pathophysiological conditions. Tissues from either saline- or LPS-treated (2 h; 65 microg/kg ip) rats were processed for RT-PCR, Western blotting, and immunohistochemistry or were mounted in organ baths where electrical field stimulation was applied in the presence or absence of CB receptor agonists. Whereas the CB2 receptor agonist JWH133 did not affect the electrically evoked twitch response of the ileum under basal conditions, in the LPS-treated tissues JWH133 was able to reduce the enhanced contractile response in a concentration-dependent manner. Rat ileum expressed CB2 receptor mRNA and protein under physiological conditions, and this expression was not affected by LPS treatment. In the myenteric plexus, CB2 receptors were expressed on the majority of neurons, although not on those expressing nitric oxide synthase. LPS did not alter the distribution of CB2 receptor expression in the myenteric plexus. In vivo LPS treatment significantly increased Fos expression in both enteric glia and neurons. This enhanced expression was significantly attenuated by JWH133, whose action was reversed by the CB2 receptor antagonist AM630. Taking these facts together, we conclude that activation of CB2 receptors in the enteric nervous system of the gastrointestinal tract dampens endotoxin-induced enhanced intestinal contractility.     

Influence of ethanolic extract of Tephrosia purpurea Linn. on mast cells and erythrocytes membrane integrity

The ethanolic extract of T. purpurea Linn. was studied for its in vitro effect on rat mast cell degranulation and erythrocyte membrane integrity in vitro. The extract in concentration of 25-200 microg/ml showed a dose-dependant inhibition of rat mast cell degranulation induded by compound 48/80 and egg albumin. T. purpurea extract was found to inhibit haemolysis of erythrocytes induced by hypotonic solution but accelerated haemolysis induced by heat at a concentration of 100 microg/ml. The studies reveal that the ethanolic extract of T. purpurea may inhibit degranulation of mast cells by a mechanism other than membrane stabilization.     

Deletion of Type-2 Cannabinoid Receptor Induces Alzheimer’s Disease-Like Tau Pathology and Memory Impairment Through AMPK/GSK3β Pathway

Although several studies have shown that type-2 cannabinoid receptor (CB2R) is involved in Alzheimer’s disease (AD) pathology, the effects of CB2R on AD-like tau abnormal phosphorylation and its underlying mechanism remain unclear. Herein, we employed the CB2R^?/? mice as the animal model to explore roles of CB2R in regulating tau phosphorylation and brain function. We found that CB2R^?/? mice display AD-like tau hyperphosphorylation, hippocampus-dependent memory impairment, increase of GSK3β activity, decrease of AMPK and Sirt1 activity and mitochondria dysfunction. Interestingly, AICAR or resveratrol (AMPK agonist) could efficiently rescue most alternations caused by solo deletion of CB2R in CB2R^?/? mice. Moreover, JWH133, a selective agonist of CB2R, reduces phosphorylation of tau and GSK3β activity in HEK293 tau cells, but the effects of JWH133 on phosphorylation of tau and GSK3β disappeared while blocking AMPK activity with compound C or Prkaa2-RNAi. Taken together, our study indicated that deletion of CB2R induces behavior damage and AD-like pathological alternation via AMPK/GSK3β pathway. These findings proved that CB2R/AMPK/GSK3β pathway can be a promising new drug target for AD.     

Functional and biochemical characterization of rat bone marrow derived mast cells

The functional and biochemical characterization of rat bone marrow derived mast cells (RBMMC) confirms both species-related differences between rat and mouse bone marrow-derived mast cells (MBMMC) as well as mast cell heterogeneity in a single species. Such RBMMC have the staining characteristics of mucosal mast cells and contain the mucosal mast cell protease. The RBMMC release the preformed granule mediator beta-hexosaminidase both in response to immunologic stimulation with 200 ng Ag (net release 15.8 +/- 3.8%) and in response to 1 microM calcium ionophore A23187 (net release 21.8 +/- 6.8%). However, compound 48/80, substance P, and somatostatin did not induce mast cell degranulation. In experiments with optimal beta-hexosaminidase release, the RBMMC generated similar quantities of the newly formed arachidonic acid metabolites leukotriene C4 and PGD2 when stimulated with either Ag or calcium ionophore A23187. The RBMMC incorporate [35S]sulfate into proteoglycans consisting of 90% chondroitin sulfates and 10% heparin. The chondroitin sulfates were comprised of chondroitin 4 sulfate and chondroitin sulfate diB sulfated disaccharides in a ratio of 4/1. Although we show that RBMMC and MBMMC share a low histamine content, functional IgE receptors and unresponsiveness to cromolyn and selective secretagogues (compound 48/80, substance P, and somatostatin), we also provide evidence that RBMMC differ from MBMMC in their profile of newly generated mediators, preformed granule proteoglycan, and lack of proliferative response to mouse IL-3.     

A study of chemically induced acute inflammation in the skin of the rat

Oedema due to application of benzene to the skin was reduced following prior sensory denervation and in animals systemically pre-treated with capsaicine (which is known to confer resistance to chemical irritants) or compound 48/80 (which depletes the body of mast cells). Increased degranulation of mast cells in the benzene-treated skin was unaffected by denervation but did not occur after treatment with capsaicine. Antidromic stimulation of a cutaneous nerve caused oedema and degranulation of mast cells, both of which were less severe than the corresponding effects of topically applied benzene. These effects were completely prevented by prior treatment with capsaicine and the oedema was less severe in 48/80-treated rats. Hence, the presence of mast cells was necessary for full development of the effects of antidromic stimulation. These observations indicate that axon reflexes in sensory fibres contribute to, but are not entirely responsible for, the development of oedema in chemically irritated skin. The prophylactic action of capsaicine may be due to the prevention of degranulation of mast cells rather than to a direct effect on cutaneous nerve endings. These conclusions are embodied in an hypothesis purporting to explain the involvement of axon reflexes, mast cells and various humoral mediators in chemically induced acute inflammation.     

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.     

Mechanisms for the coupling of cannabinoid receptors to intracellular calcium mobilization in rat insulinoma beta-cells

In RIN m5F rat insulinoma beta-cells, agonists at cannabinoid CB(1) receptors modulate insulin release. Here we investigated in these cells the effect of the activation of cannabinoid CB(1) and CB(2) receptors on intracellular Ca(2+) ([Ca(2+)](i)). The CB(1) agonist arachidonoyl-chloro-ethanolamide (ACEA), and the CB(2) agonist JWH133, elevated [Ca(2+)](i) in a way sensitive to the inhibitor of phosphoinositide-specific phospholipase C (PI-PLC), U73122 (but not to pertussis toxin and forskolin), and independently from extracellular Ca(2+). PI-PLC-dependent Ca(2+) mobilization by ACEA was entirely accounted for by activation of inositol-1,3,4-phosphate (IP(3)) receptors on the endoplasmic reticulum (ER), whereas the effect of JWH133 was not sensitive to all tested inhibitors of IP(3) and ryanodine receptors. ACEA, but not JWH133, significantly inhibited the effect on [Ca(2+)](i) of bombesin, which acts via G(q/11)- and PI-PLC-coupled receptors in insulinoma cells. The endogenous CB(1) agonists, anandamide and N-arachidonoyldopamine, which also activate transient receptor potential vanilloid type 1 (TRPV1) receptors expressed in RIN m5F cells, elevated [Ca(2+)](i) in the presence of extracellular Ca(2+) in a way sensitive to both CB(1) and TRPV1 antagonists. These results suggest that, in RIN m5F cells, CB(1) receptors are coupled to PI-PLC-mediated mobilization of [Ca(2+)](i) and might inhibit bombesin signaling.     

Comparative effect of Phoneutria nigriventer spider venom and capsaicin on the rat paw oedema

Capsaicin, the pungent component of hot peppers, and the venom of the spider Phoneutria nigriventer are able to activate sensory nerves resulting in cutaneous neurogenic plasma extravasation. This study was undertaken to compare the ability of these substances to evoke oedema in the rat hind-paw and mechanisms underlying this effect. Subplantar injection of either Phoneutria nigriventer venom (PNV; 1-100 microg/paw) or capsaicin (10-200 microg/paw) caused a significant paw oedema that was potentiated by CGRP (10 pmol/paw). In rats treated neonatally with capsaicin to deplete neuropeptides, the paw oedema induced by either PNV (100 microg/paw) or capsaicin (100 microg/paw) was partially reduced (P<0.05). The tachykinin NK1 receptor antagonist SR140333 (0.2 micromol/kg; i.v.) prevented the paw oedema induced by the tachykinin NK1 receptor agonist GR73632 (30 pmol/paw) and partially reduced paw oedema induced by PNV or capsaicin. Treatment of rats with compound 48/80 (5 mg/kg; s.c. 3 days) or with both H1 receptor antagonist (mepyramine; 1 nmol/paw) and 5-HT receptor antagonist (methysergide; 1 nmol/paw) significantly inhibited PNV- or capsaicin-induced paw oedema. The combined treatment with mepyramine and methysergide and SR140333 further reduced PNV- and capsaicin-induced paw oedema. The bradykinin B2 receptor antagonist Hoe 140 affected neither PNV- nor capsaicin-induced responses. Our results suggest that PNV and capsaicin each induce paw oedema that is partially mediated by activation of sensory fibers culminating in the release of substance P as well as by activation of mast cells which in turn release amines such as histamine and 5-HT.     

Bone Cell-autonomous Contribution of Type 2 Cannabinoid Receptor to Breast Cancer-induced Osteolysis

The cannabinoid type 2 receptor (CB2) has previously been implicated as a regulator of tumor growth, bone remodeling, and bone pain. However, very little is known about the role of the skeletal CB2 receptor in the regulation of osteoblasts and osteoclasts changes associated with breast cancer. Here we found that the CB2-selective agonists HU308 and JWH133 reduced the viability of a variety of parental and bone-tropic human and mouse breast cancer cells at high micromolar concentrations. Under conditions in which these ligands are used at the nanomolar range, HU308 and JWH133 enhanced human and mouse breast cancer cell-induced osteoclastogenesis and exacerbated osteolysis, and these effects were attenuated in cultures obtained from CB2-deficient mice or in the presence of a CB2 receptor blocker. HU308 and JWH133 had no effects on osteoblast growth or differentiation in the presence of conditioned medium from breast cancer cells, but under these circumstances both agents enhanced parathyroid hormone-induced osteoblast differentiation and the ability to support osteoclast formation. Mechanistic studies in osteoclast precursors and osteoblasts showed that JWH133 and HU308 induced PI3K/AKT activity in a CB2-dependent manner, and these effects were enhanced in the presence of osteolytic and osteoblastic factors such as RANKL (receptor activator of NFκB ligand) and parathyroid hormone. When combined with published work, these findings suggest that breast cancer and bone cells exhibit differential responses to treatment with CB2 ligands depending upon cell type and concentration used. We, therefore, conclude that both CB2-selective activation and antagonism have potential efficacy in cancer-associated bone disease, but further studies are warranted and ongoing.     

Exogenous dendritic cell homing to draining lymph nodes can be boosted by mast cell degranulation

Dendritic cells (DCs), as potent antigen presenting cells, are increasingly used for immunotherapeutic approaches, predominantly in oncology. Low efficiency of injected Ag-pulsed DC homing to draining lymph nodes (DLNs) is one of the factors that affect the efficacy of therapy. As Langerhans cell emigration was enhanced after skin mast cell degranulation, we investigated the effect of local mast cell activation on exogenous bone marrow-derived DCs (BM-DCs) homing to DLNs. Product of activated MC/9 mast cells enhanced chemotaxis of BM-DCs to CCL21 in vitro. Intradermal injection of compound 48/80 (c48/80) induced local skin mast cell obvious degranulation and boosted exogenous BM-DC homing to DLNs. Both Ag-specific lymphocyte proliferation and TH1/TH2 cytokine production increased after HBsAg-pulsed BM-DC was injected into c48/80 pretreated mice. These results suggest that transferred DC homing to DLNs promoted by local mast cell degranulation may have potential application to improve DC-based immunotherapy.     

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.     

Cannabinoid receptor CB2 protects against balloon-induced neointima formation

Cannabinoid receptor CB(2) activation inhibits inflammatory proliferation and migration of vascular smooth muscle cells in vitro. The potential in vivo relevance of these findings is unclear. We performed carotid balloon distension injury in hypercholesterolemic apolipoprotein E knockout (ApoE(-/-)) mice receiving daily intraperitoneal injection of the CB(2) agonist JWH133 (5 mg/kg) or vehicle, with the first injection given 30 min before injury. Alternatively, we subjected CB(2)(-/-) and wild-type (WT) mice to balloon injury. We determined CB(2) mRNA and protein expression in dilated arteries of ApoE(-/-) mice. Neointima formation was assessed histologically. We used bone marrow-derived murine CB(2)(-/-) and WT macrophages to study adhesion to plastic, fibronectin, or collagen, and migration was assayed by modified Boyden chamber. Aortic smooth muscle cells were isolated to determine in vitro proliferation rates. We found increased vascular CB(2) expression in ApoE(-/-) mice in response to balloon injury. Seven to twenty-one days after dilatation, injured vessels of JWH133-treated mice had less intimal nuclei numbers as well as intimal and medial areas, associated with less staining for proliferating cells, smooth muscle cells, and macrophages. Complete endothelial repair was observed after 14 days in both JWH133- and vehicle-treated mice. CB(2) deficiency resulted in increased intima formation compared with WT, whereas JWH133 did not affect intimal formation in CB(2)(-/-) mice. Apoptosis rates assessed by in situ terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling staining 1 h postballooning were significantly higher in the CB(2) knockouts. In vitro, bone marrow-derived CB(2)(-/-) macrophages showed enhanced adherence and migration compared with WT cells and elevated mRNA levels of adhesion molecules, chemokine receptors CCR1 and 5, and chemokine CCL2. Proliferation rates were significantly increased in CB(2)(-/-) smooth muscle cells compared with WT. In conclusion, pharmacological activation or genetic deletion of CB(2) receptors modulate neointima formation via protective effects in macrophages and smooth muscle cells.     

Role of histamine in the inhibitory effects of phycocyanin in experimental models of allergic inflammatory response

It has recently been reported that phycocyanin, a biliprotein found in the blue-green microalgae Spirulina, exerts anti-inflammatory effects in some animal models of inflammation. Taking into account these findings, we decided to elucidate whether phycocyanin might exert also inhibitory effects in the induced allergic inflammatory response and on histamine release from isolated rat mast cells. In in vivo experiments, phycocyanin (100, 200 and 300mg/kg post-orally (p.o.)) was administered 1 h before the challenge with 1 microg of ovalbumin (OA) in the ear of mice previously sensitized with OA. One hour later, myeloperoxidase activity and ear edema were assessed. Phycocyanin significantly reduced both parameters. In separate experiments, phycocyanin (100 and 200 mg/kg p.o.) also reduced the blue spot area induced by intradermal injections of histamine, and the histamine releaser compound 48/80 in rat skin. In concordance with the former results, phycocyanin also significantly reduced histamine release induced by compound 48/80 from isolated peritoneal rat mast cells. The inhibitory effects of phycocyanin were dose dependent. Taken together, our results suggest that inhibition of allergic inflammatory response by phycocyanin is mediated, at least in part, by inhibition of histamine release from mast cells.     

Hormone-responsive alkaline proteinase in rat skeletal muscle is not a mast cell-derived enzyme

Proteinase activity was determined in myofibrils from intact rat skeletal muscle and from skeletal muscle myocytes grown in culture. In vivo administration of the mast cell degranulator compound 48/80 abolished the alkaline proteinase activity in myofibrils obtained from normal or streptozotocin-diabetic rats. Exposure of myocytes to compound 48/80 in cell cultures had no effect on their myofibrillar proteinase activity, nor did it affect the rate of overall protein degradation in these cells. Co-incubation of cultured mast cells (line P815Y) with myocytes followed by sonication of the cell mixture resulted in a marked reduction of the proteinase activity in the pellet fraction, suggesting that the mast cells contain inhibitor(s) of myofibrillar proteinase activity. It is suggested that the myofibril-bound alkaline proteinase activity is not a mast cell-derived enzyme but a genuine component of muscle cells. The in vivo 48/80-induced reduction of muscle myofibrillar proteinase activity appears to be due to release of a soluble inhibitory activity rather than removal of mast cell proteinase from the tissue by degranulation.     

Mast cell stabilizing and lipoxygenase inhibitory activity of Cedrus deodara (Roxb.) Loud. wood oil

Volatile oil of C. deodara, administered orally at the doses of 50, 100 and 200 mg/kg body weight, significantly inhibited the pedal edema induced by compound 48/80 in rats. The oil significantly inhibited compound 48/80 induced degranulation of isolated rat peritoneal mast cells at concentrations ranging from 25-200 micrograms/ml. C. deodara wood oil also significantly inhibited the enzyme lipoxygenase at a concentration of 200 micrograms/ml. Thus, the anti-inflammatory activity of C. deodara wood oil could be attributed to its mast cell stabilizing activity and the inhibition of leukotriene synthesis.     

The CD200 receptor is a novel and potent regulator of murine and human mast cell function

CD200R is a member of the Ig supergene family that is primarily expressed on myeloid cells. Recent in vivo studies have suggested that CD200R is an inhibitory receptor capable of regulating the activation threshold of inflammatory immune responses. Here we provide definitive evidence that CD200R is expressed on mouse and human mast cells and that engagement of CD200R by agonist Abs or ligand results in a potent inhibition of mast cell degranulation and cytokine secretion responses. CD200R-mediated inhibition of FcepsilonRI activation was observed both in vitro and in vivo and did not require the coligation of CD200R to FcepsilonRI. Unlike the majority of myeloid inhibitory receptors, CD200R does not contain a phosphatase recruiting inhibitory motif (ITIM); therefore, we conclude that CD200R represents a novel and potent inhibitory receptor that can be targeted in vivo to regulate mast cell-dependent pathologies.     

Brain mast cell degranulation regulates blood-brain barrier

Mast cells synthesize vasoactive agents and a number of neurotransmitters. They are particularly numerous in the medial habenular region of the epithalamus, the attachment site of the choroid plexus. The present study examined whether degranulation of brain mast cells alters the permeability of the blood-brain barrier (BBB). To this end, doves were injected intramuscularly with the mast cell degranulator, compound 48/80 (C40/80), followed by intravenous injection of Evans blue. The distribution of the dye in the parenchyma was examined using digital imaging. Three brain areas were analyzed: the medial habenula (which also contains mast cells), the paraventricular nucleus (PVN, which abuts the third ventricle, but has no mast cells), and the lateral septal organ (LSO, a circumventricular organ with fenestrated capillaries). Significantly more Evans blue tracer and fewer toluidine blue-positive mast cells were detected in the medial habenula of subjects treated with C48/80 compared to saline controls. Evans blue did not enter the PVN in either the experimental or control group, while it entered the LSO equally in both. Degranulation of mast cells after C48/80 treatment was confirmed histochemically and ultrastructurally. The results support the hypothesis that brain mast cell degranulation locally alters BBB permeability. Activation of brain mast cells may provide a mechanism for regulated opening of the BBB. © 1996 John Wiley & Sons, Inc.     

Degranulation of mast cells due to compound 48/80 induces concentration-dependent intestinal contraction in rainbow trout (Oncorhynchus mykiss Walbaum) ex vivo

Rainbow trout (Oncorhynchus mykiss) intestinal strips (n = 10) were mounted in an isolated organ bath and the effect of incremental doses of compound 48/80 was recorded. Compound 48/80 induced concentration-related contraction in all the examined strips following a sigmoidal dose-response curve fit. Values for maximal contraction (E(max) , g?cm(-2)), negative logarithm of the EC(50) (pD(2)), and hill slope were, respectively (mean±standard error), 12.88 ± 0.51, 1.88 ± 0.05, 1.49 ± 0.27. The histological modification induced on mast cells (MCs) due to compound 48/80 was characterized by mean of gray-levels and texture analysis. Significant differences were observed between gray-levels values (Linear mixed model, P<0.01), contrast, and entropy (Linear mixed model, P<0.05) of MCs from compound 48/80-treated strips compared with MCs from untreated strips. Moreover, maximal intestinal contraction (due to compound 48/80) correlates positively and significantly (Pearson and Spearman correlations, P<0.05) with degranulation intensity determined by means of gray-levels analysis. Four antisera were tested on intestinal sections and no MCs positive to serotonin, substance P, met-enkephalin, and bombesin were found. This study demonstrates that compound 48/80 induces the degranulation of trout intestinal MCs ex vivo, and that the aforementioned degranulation promotes a concentration-dependent intestinal contraction.     

Immunomodulatory activity of boswellic acids of Boswellia serrata Roxb

Extract of gum resin of B. serrata containing 60% acetyl 11-keto beta boswellic acid (AKBA) along with other constituents such as 11-keto beta-boswellic acid (KBA), acetyl beta-boswellic acid and beta-boswellic acid has been evaluated for antianaphylactic and mast cell stabilizing activity using passive paw anaphylaxis and compound 48/80 induced degranulation of mast cell methods. The extract inhibited the passive paw anaphylaxis reaction in rats in dose-dependant manner (20, 40 and 80 mg/kg, po). However, the standard dexamethasone (0.27 mg/kg, po) revealed maximum inhibition of edema as compared to the extract. A significant inhibition in the compound 48/80 induced degranulation of mast cells in dose-dependant manner (20, 40 and 80 mg/kg, po) was observed thus showing mast cell stabilizing activity. The standard disodium cromoglycate (50 mg/kg, ip) was found to demonstrate maximum per cent protection against degranulation as compared to the extract containing 60% AKBA. The results suggest promising antianaphylactic and mast cell stabilizing activity of the extract.