Neurotensin inhibits glucose but not glucagon-induced insulin and somatostatin release in isolated islets.

The effects of neurotensin on insulin and somatostatin release were examined in isolated pancreatic islets prepared from 3-4 days rats, and maintained in culture for 48 h before use. In the presence of 12 mM glucose, glucagon (50-2,000 ng/ml, i.e. 14-560 nM) caused a 2-fold increase in insulin and somatostatin release. Neurotensin (150 ng/ml, i.e., 100 nM) did not affect the glucagon-stimulated release, nor did it alter the release of either peptide measured at 12 mM glucose in the absence of glucagon. In contrast, neurotension markedly inhibited the release of both insulin and somatostatin that was induced by 23 mM glucose. These observations suggest that neurotensin may modulate the release of insulin and somatostatin evoked by high glucose concentrations, but not that resulting from the action of glucagon on pancreatic islets.