BACKGROUND
In allergic diseases mast cells plays an important role by defending the antigens.1 IgE antibodies formed in response to antigen antibody complex attaches to the surface receptors of mast cells and rises calcium influx leading to degranulation of mast cells which releases some pro-inflammatory mediators (also known as local hormones) such as histamine and eicosanoids.2
Aim: Aim of this experiment is to screen anti-allergic activity of the drugs.
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REQUIREMENTS
Animals: Guinea pigs of 400-600 g of either sex,
Albino rats of 175-200 g of either sex
Drugs: Histamine dihydrochloride aerosol (0.2% w/v)
Chlorpheniramine maleate (2 mg/kg, s.c.)
Disodium chromoglycate (50 mg/kg. i.p.)
Reagents: Saline solution (0.9%)
RPMI 1640 buffer medium (PH 7.2-7.4)
egg albumin (100 µg/mL)
toludine blue solution (1%)
Instruments: Microscope with 10X magnification lens
PROCEDURE
Evaluation of bronchoconstriction in guinea pigs by using histamine aerosol
Selected guinea pigs are divided into two groups consisting of 3 animals in each. Animals have to be fasted overnight. Group-1 receives normal saline. Group-2 animals receive Chlorpheniramine maleate (2 mg/kg, S.C.). Before the drug treatment animals should be exposed to histamine aerosol (0.2%) in histamine chamber.
Then determine the end point i.e. pre-convulsion dyspnea (PCD) is the time of time of exposure of histamine aerosol to onset of dyspnea that leads to convulsion. As early as PCD is observed the animals should be removed from chamber and placed in fresh air and time of onset of PCD is to be noted on day zero.
Then animals have to treat with drug after 24 hours. After 1 hr of drug administration once again animals are exposed to histamine aerosol and PCD is determined. Percentage (%) of protection offered by the drug can be calculated by the below formula.3
Percentage (%) protection= (1-T1/T2)×100
Where T1= mean value of PCD before drug administration, T2= mean value of PCD after drug administration.
OBSERVATIONS
| Group | Percentage protection |
| Group-1 (saline) | |
| Group-2 (Chlorpheniramine maleate (2 mg/kg, S.C.) |
Mast cell stabilization activity
Albino rats of either sex are divided into two groups consisting of 3 animals in each. Group-1 receives normal saline, and Group-2 receives Disodium chromoglycate (50 mg/kg. i.p.) for 3 days. Inject 10 ml/kg of 0.9% saline into peritoneal cavity on 4th day to each animal.
Massage the peritoneal region of the animal gently for 5 min, then collect the peritoneal fluid and transfer to the test tube which is carrying 7-10 ml of RPMI buffer. Centrifuge the fluid for 400-500 RPM. Discard the supernatant and wash the pellets of mast cells twice with same buffer by centrifugation.
Add egg albumin to the above cell suspension and incubate at 37oC for 10 min. Later the suspension has to stain with 1% toluidine blue solution and observe the slide under microscope for calculating number of granulated and degranulated mast cells in each group (total 100 cells are has to be counted from different visual areas).4
OBSERVATIONS
| Group | Total number of cells (n=100) | |
| Granulated | Degranulated | |
| Group-1 (saline) | ||
| Group-2 (Disodium chromoglycate (50 mg/kg. I.P.) | ||
CONCLUSION
Pretreatment of animals with standard drugs stabilizes mast cell membrane and generates nitric oxide as defensive mechanism that inhibits the release of chemokines, which are responsible for vasoconstriction.[/vc_column_text]
REFERENCES
- Prussin C, Metcalfe DD. IgE, Mast cells, Basophils and Eosinophils. J Allergy Clin Immunol. 2003;111(2):486-94.
- Choudhary GP. Mast Cell Stabilizing Activity of Piper longum Linn. Indian J Allergy Asthma Immunol. 2006;20:112-6.
- Hajare R, Darvhekar VM, Shewale A, Patil V. Evaluation of antihistaminic activity of Piper betel leaf in guinea pig. African J Pharmacy Pharmacol. 2011;5(2):113-7.
- Taur DJ, Patil RY. Mast cell stabilizing and antiallergic activity of Abrus precatorius in the management of asthma. Asian Pacific J Trop Med. 2011; 4(1):46-9.
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