Dexamethasone makes the gastric mucosa susceptible to ulceration by inhibiting prostaglandin synthetase and peroxidase – two important gastroprotective enzymes
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
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| Title |
Dexamethasone makes the gastric mucosa
susceptible to ulceration by inhibiting
prostaglandin synthetase and peroxidase
– two important gastroprotective enzymes
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| Creator |
Bandyopadhyay, Uday
Biswas, Kausik Bandyopadhyay, Debashis Ganguly, Chayan K Banerjee, Ranajit K |
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| Subject |
Cell Biology & Physiology
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| Description |
The plausible mechanism by which dexamethasone makes the gastric mucosa susceptible to ulceration has been studied. As
acid aggravates ulcer, the role of dexamethasone on acid secretion was first investigated. Dexamethasone stimulates both basal
and drug (mercaptomethylimidazole)-induced gastric acid secretion by 100 and 50% respectively in male Wister rats 24 h after
intramuscular administration at the dose of 1 mg/kg body wt. This stimulated acid secretion is 93% blocked by cimetidine
indicating increased liberation of histamine in the process. Pretreatment of dexamethasone before 24 h produces ulcer in 30%
of the pylorus- ligated rats and aggravates the ulcer index by 82% in both pylorus and esophagus ligated rats. The incidence of
ulceration in the latter cases is also increased by 25%. As mucosal prostaglandin synthetase and peroxidase play an important
role in gastroprotection through biosynthesis of prostaglandin and by scavenging endogenous H2O2 respectively, the effect
of dexamethasone on the activities of these gastroprotective enzymes were studied. Prostaglandin synthetase and peroxidase
activities of the mucosa are significantly inhibited by 87 and 83% respectively by 24-h pretreatment with dexamethasone.
The results indicate that dexamethasone makes the mucosa prone to ulceration by inhibiting the activity of prostaglandin
synthetase to block the gastroprotective action of prostaglandin and also by inhibiting the peroxidase, thereby elevating the
endogenous H2O2 level to generate more reactive hydroxyl radical responsible for the mucosal damage. (Mol Cell Biochem
202: 31–36,1999)
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| Date |
1999
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/719/1/MOLECULAR_AND_CELLULAR_BIOCHEMISTRY_202(_1%2D2)_31%2D36;1999[6].pdf
Bandyopadhyay, Uday and Biswas, Kausik and Bandyopadhyay, Debashis and Ganguly, Chayan K and Banerjee, Ranajit K (1999) Dexamethasone makes the gastric mucosa susceptible to ulceration by inhibiting prostaglandin synthetase and peroxidase – two important gastroprotective enzymes. Molecular and celluler Biochemistry, 202 (1-2). pp. 31-36. |
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| Relation |
http://dx.doi.org/10.1023/A:1007018212822
http://www.eprints.iicb.res.in/719/ |
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