Asthma intro. Pathophysiology of asthma. Animal model Model developed using plant extracts

1. Animal Model of Anti-asthmatic Drugs
Ansar Laskar
M.Pharm in Pharmacology, 1st Year
Maulana Abul Kalam Azad University of
Technology, WB

2. Contents
Introduction
Etiology
Pathophysiology
Necessity of Animal model studies
Development of Animal model
 Mice
 Rat
 Guinea-pigs
Anti-asthmatic activity
 plant extract of Leucas aspera using animal model
Conclusion
Reference

3. Asthma:
Asthma is a chronic inflammatory disorder of the airway that occurs
commonly in both children and adults. Which results, physiologically
in hyper-reactivity and clinically, in recurrent episodes of wheezing,
chest tightness, breathlessness and coughing.
Asthmatic response can be divided into two categories early and late
asthma. Chronic asthma is characterised by airway inflammation and
airway hyper-responsiveness.

4. Etiology
Genetic Factors
• Family history
• Certain genes
Environmental Factors
• Allergens- Domestic mites, furred animal (dogs, cats), cockroach, fungi,
pollens.
• Pollutants (particularly environmental tobacco smoke).
• Respiratory infections.
• Drugs (aspirin, beta blockers).

5. Pathophysiology :
Bronchoconstriction
Mucous build-up
Inflamed mucosa
 Allergens contact with antigen
presenting cell, called Dendritic cell.
 After Phagocytosis allergen activate
particular gene MHC-2 on it’s cell
membrane.
 Th-2 cell express on it’s cell membrane
T cell receptor & CD-4 molecule , this
CD-4 is going to interact with the
MHC-2 molecule & produce IL-4,IL-
5,IL-13.
 IL-4/IL-13 activate plasma cell and
produce IgE antibodies which bind
with mast cell that release histamines,
leukotrienes.
 IL-5 activate eosinophil which produce
proteases & leukotrienes.
MHC-2
Allergen

6. Necessity of Animal model studies :
Ideally, to increase our knowledge of the processes behind this disease and to identify
critical pathways, and therefore research should be conducted in-depth targets for drug
therapies conducted on human asthmatic.
However, for find out the actual reason, the types of experiment is necessary to precisely
examine the mechanisms that are involved at cellular and molecular levels, that are not
possible in humans due to ethical and logistical limitations. A system for modelling the
process needs to be developed to determine the importance of the identified mediator.
Development of Animal model :
Mice :
For sensitization, BALB/c mice received an i.p injection of OVA (ovalbumin) or PBS
(phosphate-buffered saline) with aluminum hydroxide on days 1, 7 and 14.
From days 21 to 25, the mice were challenged with aerosolized 5% OVA or PBS in a
plexiglass chamber for 30 minutes per day.
Samples were collected on day 25.
Mice were sacrificed on day 26 for airway hyper-reactivity (AHR) measurements and
sacrificed on day 25 (4 days after the first challenge) for the examination of inflammatory
infiltrates, cytokine production.

7. A mice model of OVA-induced asthma

8. Rat :
Like mice, rat can be easily sensitized to a range of neo-antigens such as OVA, HDM extracts and
Ascaris antigens.
Again, sensitization and challenge in rats typically results in a Th2 dominated response characterized by
eosinophilia and antigen specific IgE.
The strain chosen has a significant impact on the level of responses in these markers of immunology and
inflammation.
Similar to the mouse, this variant, combined with knowledge of the genetics and immunology of the
species, is one of the main benefits of using inbred rats as a model for asthma.
Sensitized rats have been shown, using appropriate methods for measuring, but also acute responses to
allergen inhalation.
Guinea-pigs :
As one of the earliest animal models of allergic airway reactions, investigations on guinea pigs.
Guinea pigs are easily sensitive to OVA, just as the rodent asthma models it is simple to induce a
response to challenge that is similar to an asthmatic phenotype that involves eosinophilia and increased
airway responsiveness.

9. Anti-asthmatic activity :
Anti-asthmatic activity of plant extract of Leucas aspera using animal model:
Animal models
 Guinea pig:
• Histamine induced bronchospasm in conscious guinea pig– Histamine or other bronchospsmogen can cause
symptoms such asphyctic convulsions that resemble bronchial asthma in guinea pigs. The occurrence of these
symptoms may be delayed by bronchodilator drugs.
• Procedure- Animals with nearly same preconvulsion time were selected and randomly divided into four groups
of six animals each.
Group 1: Normal control - Distilled water
Group 2: Asthmatic control- 0.5% Histamine HCl aerosol.
Group 3: Standard treatment - 0.5% Histamine HCl aerosol with Mepyramine (8 mg/kg, p.o.)
Group 4: Test treatment - 0.5% Histamine HCl aerosol with L.aspera Methanolic extract (100 mg/kg, p.o.)
The experimental animals were kept in a closed chamber and exposed to an aerosol of 0.5% histamine
dihydrochloride and preconvulsion time was measured. Two hours after the above drug treatment, animals were
exposed to histamine aerosol and pre-convulsion time was noted. As soon as dysponea occurs, it leads to the
appearance of convulsion. Animals were removed from the chamber and placed in fresh air to recover.
• Parameter- Symptoms like increased breathing frequency, forced inspiration and asphyctic convulsion was
observed
Results
• When the animals were exposed to the aerosol of 0.5% histamine, there was a bronchospasm seen in form of
Pre-Convulsion Dyspnoea (PCD) at day 0. Pre-treatment with the standard drug Mepyramine (8mg/kg, p.o.) and
L. aspera Methanolic extract (100 mg/kg, p.o.) given 2 hour before aerosol exposure to guinea pigs significantly
increased Preconvulsion dyspnoea Time at day 15.

10. Table 1. Effect of Methanolic extract of Leucas aspera on histamine induced bronchospasm in conscious guinea pigs
MELA- Methanolic Extract of Leucas aspera
PCT- Preconvulsion dyspnoea Time

11. Conclusion :
Animal model remain the easiest way to understand pathophysiology of allergic asthma
and to help developing new drugs and immunotherapy strategies for the treatment of this complex
disease. Histamine induced bronchoconstriction is a traditional immunological model of antigen
airway obstruction. However, treatment with standard and Methanolic extract of L. aspera shows
significant anti-histaminic, dronchodilatory, anti-inflammatory activity in various anti-asthmatic
models. Thorough various studies of screening methods for anti-asthma activities might give some
valuable information towards further research so, that it gives novel therapeutic development of
effective and potent anti-asthmatic agents.

12. Reference :
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6. Dorsch W, Wagner H. New antiasthmatic drugs from traditional medicine?. International Archives of
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13. Thank You