The opioid peptide DAMME modulates histamine's content in gastric mucosa of the rat

The effects of a synthetic Met-enkephalin analogue [ d -Ala 2 ,MePhe 4, Met(O) 5 -ol]enkephalin (DAMME) (1 mg/kg, IP) on gastric damage produced by necrotizing agents (0.6 N HCl, ethanol 1 ml/rat, PO) were evaluated, and the correlation between histamine and opioids in stomach was investigated. Rats pretreated with DAMME had significantly less severe lesions and lower histamine content in gastric tissue. The histamine level, expressed in mg/g of gastric tissue, changed from 0.41 ± 0.10 of control animals to 1.33 ± 0.12 for HCl and 1.51 ± 0.20 for ethanol treatment, whereas in animals pretreated with DAMME the values were significantly reduced to 0.55 ± 0.13 and 0.65 ± 0.15. These results confirm a link between the gastroprotection produced by opioids and the modulation of histaminergic activity in the rat stomach.