Study of anti-ulcer activity of a drug using pylorus ligand (SHAY) rat model

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BACKGROUND

Study of anti-ulcer activity of a drug using pylorus ligand (SHAY) rat model. Peptic ulcer is one of the most prevalent gastrointestinal disorders. The aim of the present study is to demonstrate the antiulcer activity of drugs using pylorus ligand (SHAY) rat model.

This was first demonstrated by Shay in 1945. Ligation of rat pylorus results gastric acid accumulation in the fore-stomach leads to acute gastric ulcers. This procedure is used to screen the drugs for their anti-secretary and antiulcer activity.¹

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REQUIREMENTS

Animals: Albino Wistar rats of 150-200 g are selected for the study.

Drugs: Ether (anesthetic), Ranitidine 20 mg/kg, p.o, 0.9% normal saline

Reagents: 0.1 N NaOH, Phenolphthalein, Topfer’s reagent,

Instruments: Dissecting microscope (10X magnification lens), Burette, P^H meter, Surgical instruments.

PROCEDURE

Animals are to be divided into two groups consisting of 3 animals in each group. Saline is to be administered to control group and Ranitidine (20 mg/kg, P.O.) to other group. Animals have to be fasted for one day with free access to water. 30 min prior to ligation process, the drug (Ranitidine) should be given.

Under light ether anesthesia a midline abdominal incision is made and pylorus will be ligated with proper care and the wound is closed. Then rats are to be placed individually in separate cages without food and water during this period and allowed them to recover.

Sacrifice the animals by decapitation after 4 hours and open the stomach and collect the stomach contents in a centrifuge tube. Determine the P^H P^H meter. Open the greater curvature of the stomach and clean the part with saline. Under 10X magnification lens ulcers are to be observed and ulcer index is calculated by using the formula given below.²

Ulcer index= (U1 + U2+ U3) × 10^-1

U1 = Average of number of ulcers per animal

U2 = Average of severity score

U3 = Percentage (%) of animals with ulcer

Intensity of ulcers with scoring: 0 – normal coloration; 0.5 – red coloration; 1 – spot ulcer; 1.5 – hemorrhagic stress; 2 – deep ulcer; 3 – perforations.

Ulcer score: 1 mm (exact) = 1; 1-2 mm = 2; >2 mm = 3; >3 mm = 4

Analysis of stomach contents

Measure total volume of gastric content and centrifuge at 1000 rpm for 10 minutes. Pipette out one ml of supernatant liquid of the centrifuged content and dilute with 10 ml distilled water. Titrate the liquid against 0.01N NaOH using Topfer’s reagent as indicator, till the end point (appearance of orange colour).

The volume of NaOH used is to be noted to estimate free acidity. Titration has to be continued till the appearance of pink colour and the volume of NaOH run down is to be noted to calculate total acidity.³

Calculation of acidity is given below:

OBSERVATIONS

Group	Volume of gastric contents (in ml)	P^H	Free acidity (mEq/l)	Total acidity (mEq/l)	Ulcer index
Control (saline)
Standard (Ranitidine 20 mg/kg P.O)

CONCLUSION

Comparison of ulcer index between study groups estimates the potency of antiulcer activity of test drug. Decrease in volume of gastric contents, free and total acidity determines anti-secretory activity of test drug and rise in P^H evaluates acid neutralizing action of the drug.

REFERENCES

Shay H. A simple method for the uniform production of gastric ulceration in the rat. Gastroenterol. 1945;5:43–61.
Vinothapooshan G, Sundar K. Anti-ulcer activity of Mimosa pudica leaves against gastric ulcer in rats.
RJPBCS. 2010;1(4):606-14.
Krishnan D. Screening of anti-ulcer drugs. Available at: https://www.slideshare.net/DivyaKrishnan4/screening-of-anti-ulcer-drugs-dr-divya-krishnan. Accessed on 10 September 2017.

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