Actions and cross-reactivity of antiallergic agents and a calcium channel antagonist on rat peritoneal mast cells. Difference in the action mechanisms and cross-reactivity among the agents

Synthesis and Evaluation of New Phthalazine Urea and Thiourea Derivatives as Carbonic Anhydrase Inhibitors

A new series of phthalazine substituted urea and thiourea derivatives were synthesized, and their inhibitory effects on the activity of purified human carbonic anhydrases (hCAs I and II) were evaluated. 2H-Indazolo[2,1-b]phthalazine-trione derivative(1)was prepared with 4-nitrobenzaldehyde, dimedone, and phthalhydrazide in the presence of TFA in DMF, and nitro group was reduced to amine derivative(2)with SnCl2·2H2O. The compound was reacted with isocyanates and isothiocyanates to get the final products(3a–p). The results showed that all the synthesized compounds inhibited the CA isoenzymes activity.3a(IC50= 6.40 µM for hCA I and 6.13 µM for hCA II) has the most inhibitory effect. The synthesized compounds are very bulky to be able to bind near the zinc ion, and they much more probably bind as the coumarin derivatives.

Effect of topical application of Brazilian propolis on scratching behavior induced by compound 48/80 in mice

BACKGROUND AND AIM

We investigated the effect of topical application of Brazilian propolis on scratching behavior induced by compound 48/80 in mice.

RESULTS

Propolis inhibited compound 48/80-induced scratching behavior when applied immediately after treatment with propolis at a dose of 3 mg/site. Dibucaine 0.3 mg/site also significantly inhibited compound 48/80-induced scratching behavior immediately after application. On the other hand, propolis inhibited compound 48/80-induced scratching behavior even 15, 30 and 60 min after application; however, dibucaine showed no significant inhibition of compound 48/80-induced scratching behavior 15, 30 and 60 min after application. In addition, propolis had no effect on increased vascular permeability just after application, but the drug had a significant effect 15, 30 and 60 min after application. On the contrary, histamine-induced scratching behavior was inhibited significantly by propolis just after application. On the other hand, propolis significantly inhibited histamine release from rat mast cells induced by compound 48/80 at a concentration of more than 10 microg/ml.

CONCLUSION

From these results, it can be concluded that inhibition of scratching behavior induced by topical application occurred by both its local anesthetic and systemic action through inhibition of histamine release.

Modulation of gastric hemorrhage and ulceration by oxidative stress and histamine release in Salmonella typhimurium-infected rats

Infection with Salmonella typhimurium can produce multiple organ dysfunctions. However, document concerning with gastric hemorrhagic ulcers occur in this infectious disease is lacking. The aim was to study modulation of gastric hemorrhagic ulcer by oxidative stress and mast cell histamine in S. typhimurium-infected rats. Additionally, the protective effects of drugs, such as ofloxacin, lysozyme chloride, ketotifen, ranitidine, and several antioxidants, including exogenous glutathione (GSH), allopurinol and dimethylsulfoxide (DMSO) were evaluated. Male Wistar rats were injected intrajejunally with a live culture of S. typhimurium (1 x 10(10) colony-forming units/rat) and followed by deprivation of food for 36 h. Age-matched control rats received sterilized vehicle only. Rat stomachs were irrigated for 3 h with either normal saline or a simulated gastric juice containing 100 mM HCl, 17.4 mM pepsin and 54 mM NaCl. S. typhimurium caused aggravation of offensive factors, including enhancing gastric acid back-diffusion, mucosal lipid peroxide generation, histamine release, microvascular permeability and hemorrhagic ulcer, as well as an attenuation of defensive substances, such as mucosal GSH and mucus level. Intragastric irrigation of gastric juice caused further aggravation of these gastric biochemical parameters. This exacerbation of ulcerogenic factors was abolished by pretreatment of ofloxacin and lysozyme chloride. Antioxidants, such as reduced GSH, allopurinol and DMSO also produced significant (P < 0.05) amelioration of gastric damage in S. typhimurium infected rats. In conclusion, gastric oxidative stress and histamine play pivotal roles in the formation of hemorrhagic ulcers that were effectively ameliorated by ofloxacin, lysozyme chloride, ketotifen, ranitidine, diamine oxidase and various antioxidants in S. typhimurium-infected rats.

Role of histamine and acid back-diffusion in modulation of gastric microvascular permeability and hemorrhagic ulcers in Salmonella typhimurium-infected rats

Documentation concerning the pathogenesis of gastric hemorrhagic ulcer in Salmonella typhimurium (Salmonella typhi)-infective disease is lacking. This research first proposed that alterations of mast cell histamine release, gastric acid back-diffusion and mucosal microvascular permeability are important in modulating gastric ulcer and hemorrhage in Salmonella typhi-infected rats. Additionally, effects of several histamine-related drugs on this ulcer model were evaluated. Male Wistar rats were deprived food for 36 h. Live cultures of Salmonella typhi (OU 5045, 1 x 10(10) CFU in 1.0 mL of sterilized phosphate buffer saline) were challenged, intrajejunally to rats just before withdrawal of food. Control rats received the same volume of sterilized vehicle only. Rat stomachs were irrigated for 3 h with either normal saline or simulated gastric juice. Gastric acid back-diffusion, mucosal histamine concentration, microvascular permeability as well as luminal hemoglobin content and ulcer areas were determined. Severe gastric hemorrhage and mucosal ulcerations, particularly in acidic stomachs, were observed in Salmonella typhi-infected rats. A positive correlation of histamine to gastric hemorrhage and ulcer was found in those rats with Salmonella typhi-infection. This hemorrhagic ulcer in Salmonella typhi-infected rats was effectively ameliorated by intraperitoneal ketotifen, diphenhydramine and ranitidine but was worsen by exogenous histamine or diamine oxidase. In conclusion, enhancement of acid back-diffusion, mast cell histamine release and microvascular permeability is important in modulating gastric hemorrhage and ulcer in Salmonella typhi-infected rats.

Gastric mucosal damage induced by arecoline seizure in rats

In an attempt to know the relation of seizure and gastric mucosal damage, we challenged arecoline (ACL) centrally to induce seizure and investigated gastric hemorrhagic injury in acid-irrigated stomachs of rats. The protective effects of several drugs also were evaluated. After deprivation of food for 24 h, rats were received laparotomy under diethylether-anesthesia. Both pylorus sphincters and carotid esophagus were ligated. The forestomach was equipped with a cannula for gastric irrigation. After recovery from anesthesia (approximately 1 h), the stomach was irrigated for 2 h with an acid solution containing 100 mM HCl and 54 mM NaCl or the same volume of normal saline. Intracerebroventricular (i.c.v.) ACL (0, 1, 3 or 10 mg/kg dissolved in 10 microl of CSF) was challenged to rats immediately after gastric irrigation. The seizure in rats was produced by ACL in a dose-related manner. The ulcerogenic parameters such as decrease of gastric mucosal glutathione levels and increase of histamine concentrations and lipid peroxide generations as well as the raise of luminal hemoglobin contents and exacerbated mucosal lesions were obtained depending on the doses of ACL challenged. These ulcerogenic parameters produced in ACL (10 mg/kg, i.c.v.) seizure rats were markedly ameliorated by gastric vagotomy or central anticholinergics. Intraperitoneal ketotifen, zinc sulfate, diphenhydramine or cimetidine also produced significant (p<0.05) inhibitions of these ulcerogenic parameters in ACL seizure rats. In conclusion, central ACL seizure may produce gastric oxidative stress and hemorrhagic lesions via vagal nervous activation and histamine release in acid-irrigated stomachs of rats.

Importance of histamine, glutathione and oxyradicals in modulating gastric haemorrhagic ulcer in septic rats

1. The ulcerogenesis of gastric haemorrhagic damage during sepsis is unclear. The present study first proposes that gastric haemorrhagic ulcer is modulated by mucosal glutathione, histamine and oxyradicals in lipopolysaccharide (LPS)-induced sepsis in rats. The protective effects of several drugs on the ulcerogenic parameters also were evaluated. 2. Male specific pyrogen-free Wistar rats were deprived of food for 24 h. For the induction of sepsis, intravenous LPS (0, 1, 3 or 10 mg/kg in 1 mL sterilized normal saline) was challenged to rats 12 h after withdrawal of food. Rat stomachs were vagotomized, followed by irrigation for 3 h with normal saline or a physiological acid solution containing 100 mmol/L HCI and 54 mmol/L NaCl. 3. The aggravation of gastric ulcerogenic parameters, such as gastric acid back-diffusion, luminal haemoglobin content, mucosal lipid peroxide production, histamine concentration, as well as lowered concentrations of defensive substances, including mucosal glutathione, were dependent on the doses of LPS used for challenge. A high correlation was observed between mucosal histamine release and lipid peroxide production in LPS rats. 4. The ulcerogenic parameters obtained in LPS (3 mg/kg, i.v.) rats were potently attenuated by diamine oxidase, ketotifen and zinc sulphate. 5. Several oxyradical scavengers, including glutathione, dimethylsulphoxide and allopurinol, also were effective in inhibiting haemorrhagic ulcer. 6. In conclusion, gastric mucosal histamine release and oxyradical generation play pivotal roles in the formation of haemorrhagic ulcers in septic rats.

FK506 inhibition of histamine release and cytokine production by mast cells and basophils

Histamine release and cytokine production by mast cells and basophils are thought to be closely involved in the pathogenesis of allergic diseases. Some reports show that FK506 (tacrolimus hydrate) inhibited histamine release and cytokine production by mast cells and basophils. However, as the effects of FK506 has not been compared with those of clinically used drugs in those reports, the clinical relevancy of FK506 inhibition remained unclear. In this paper, we compared the actions of FK506 with those of steroids or disodium cromoglycate (DSCG) which has been clinically used. FK506 inhibited histamine release by Brown-Norway rat peritoneal mast cells more potently than steroids and especially DSCG. FK506 also inhibited histamine release by a mast rat basophilic leukemia (RBL)-1 cell line and human peripheral blood basophils, whereas steroids failed to inhibit histamine release by human basophils. FK506 as well as steroids inhibited TNF-alpha and IL-4 production by RBL-1 cells. FK506 was therefore more effective than steroids and DSCG in inhibiting histamine release, and it also had the ability of inhibiting cytokine production by mast cells as steroids do. We concluded that FK506 might regulate allergic diseases via these actions, judging from the viewpoint of clinical relevancy.

A role for mast cells in adenosine A3 receptor-mediated hypotension in the rat

1. The adenosine A3 receptor agonist, N6-2-(4-aminophenyl)ethyladenosine (APNEA) induces hypotension in the anaesthetized rat. The present experiments were carried out to explore the role of mast cells in the response. 2. Intravenous injection of APNEA (1-30 micrograms kg-1 to rats in which the A3 receptor-mediated response had been isolated by pretreatment with 8-(p-sulphophenyl) theophylline (8-SPT)), induced dose-related falls in blood pressure accompanied at higher doses by small falls in heart rate. Responses to the mast cell degranulating agent, compound 48/80 (10-300 micrograms kg-1, i.v.) were qualitatively similar to those to APNEA. 3. Pretreatment with sodium cromoglycate (0.25-20 mg kg-1, i.v.) induced dose-related, although incomplete, blockade of the hypotensive responses to APNEA. At 20 mg kg-1, sodium cromoglycate also inhibited the cardiovascular response to compound 48/80 but had no effects on those to the selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) or the selective A2A receptor agonist, 2-[p-(2-carboxyethyl)phenylamino]-5'-N-ethylcarboxamidoadenosine (CGS 21680). Lodoxamide (0.01-20 mg kg-1) also blocked selectively but incompletely the response to APNEA. 4. The cardiovascular responses to compound 48/80 (10-300 micrograms kg-1, i.v.) were markedly suppressed in animals which had received repeated doses of the compound by the intraperitoneal route. Similarly APNEA was essentially devoid of cardiovascular activity in such preparations. In contrast, responses to CPA were similar in animals treated repeatedly with compound 48/80 to those obtained in control animals. 5. Plasma and serum histamine concentrations were markedly increased associated with the pronounced hypotensive responses induced by intravenous injections of APNEA (30 or 100 microg kg-1) in the presence of 8-SPT, or compound 48/80 (300 microg kg-1).6. Taken together the data implicate the mast cell in a key role in adenosine A3 receptor-mediated hypotension in the anaesthetized rat.