Objectives: The cytoprotective effects of Met-enkephalin were evaluated on the model of alcohol induced gastric lesions in Wistar male rats. Methods: Gastric lesions were induced by 96% ethanol in four groups of rats. Pretreatment of the groups 1-4 was performed by i.p. administration of 2 ml solution per animal one hour before alcohol application as follows: 1. Controls: 2 ml of 0.9% NaCl/200 g body weight,
2. Met-enkephalin: 10 mg/kg dissolved in 0.9% NaCl, 3. Haloperidole: 10 mg/kg dissolved in 0.9% NaCl, 4. Met-enkephalin+haloperidole mixed in equal proportion. Animals were sacrificed 1 hour after alcohol application. Macroscopic gastric lesions were assessed in mm2 (meanąSE). Results: Gastric lesions did not differ significantly in controls (162ą55.8 mm2)and haloperidole pretreated animals (142ą19.8 mm2,p>0.05). In the Met-enkephalin group gastric lesions were significantly lower (67ą12.2 mm2, p<0.05) then in controls, i.e. cytoprotection was observed.
Animals pretreated with Met-enkephalin+haloperidole exhibited significantly more lesions (373ą26.2 mm2, p>0.01) than groups 1-3. Conclusions: Our results indicate that Met-enkephalin administration in the dose of 10 mg/kg i.p. significantly protects gastric mucosa from the alcohol induced lesions. This is in agreement with previously reported protective effects of Met-enkephalin in different disease and cell culture models (Janković, Acta Neurol 13:433, 1991; Štambuk et al., Croat Chem Acta 71:591, 1998). Met-enkephalin modulation by haloperidole suggests the possibility of dopaminergic system involvement in cytoprotection.