Role of endogenous opioids and peripheral mucosal protective factors in centrally induced gastroprotection

Background & aims: In the last two decades several endogenous and synthetic substances (e.g. alpha2-adrenoceptor agonists, neuropeptides, endocannabinoids) have been demonstrated to induce gastroprotection after central administration. Previously we showed that the clonidine-, cannabinoid-, substance P- and nociceptin-induced gastroprotective effects are naloxone-sensitive, indicating that the activation of opioid system is likely to be involved in these protective effects. Furthermore, we found that the endogenous µ-opioid receptor agonist endomorphin-2 (EM-2) is a highly potent gastroprotective peptide. Theref…