Effect of unmodified eel calcitonin on gastric acid secretion and gastric ulcers in the rat

A new peptide, eel calcitonin (eCT), synthesized to the sequence of calcitonin (CT) extracted from the ultimo branchial bodies of eels, is now on the market in some countries for clinical use in the treatment of Paget's disease of bone and in the prophylaxis or treatment of certain osteoporoses. We have now studied the effect of eCT on the inhibition of gastric acid secretion and protection against experimentally induced gastric ulcers in rats as other CTs have previously been shown to have such effects. EelCT shows a dose dependent inhibition of gastric acid secretion, both volume and concentration of acid - dose range 100-900 ng/Kg injected subcutaneously. Central administration is also effective at a dose of 100 ng/rat. There is no published evidence for a direct effect of CTs in the stomach and there is considerable speculation on possible mediating pathways. Somatostatin may be involved in the inhibitory effect of eCT on gastric acid secretion because when administered both centrally or peripherally eCT is ineffective in rats depleted of somatostatin by pretreatment with cysteamine. However, other mechanisms must also be involved as eCT has no preventive effect against gastric ulcers induced by ethanol but has a high index of protection against ulcers induced by cold restraint stress or indomethacin.