The VGF-Derived Neuropeptide TLQP-21 Shows No Impact on Hormone Secretion in the Isolated Perfused Rat Pancreas

TLQP-21 is a VGF-derived neuropeptide proposed to be involved in regulation of metabolism. More specifically it has been suggested that TLQP-21 has the ability to enhance glucose stimulated insulin secretion, making it a candidate for treatment of patients with type 2 diabetes. In this study, we investigated the impact of TLQP-21 on insulin, glucagon, and somatostatin secretion in the perfused rat pancreas. We found that administration of 5 and 50nM TLQP-21 had no impact on pancreatic hormone secretion at 3.5 or 8mM glucose levels. Increasing TLQP-21 (200nM) and glucose concentration (3.5 and 16mM) led to a nonsignificant decrease in glucagon secretion, though insulin and somatostatin secretory patterns remained unaffected. In a final set of experiments, perfusions were performed with infusion of 50 and 1000nM TLQP-21 to ensure sufficient stimulation. However, administration of TLQP-21 under this setup showed no impact on the pancreatic hormone secretion either. In conclusion, the outcome of this study does not concur with previous findings, suggesting that the effect of TLQP-21 does not directly involve silent hormone secretion.