[HTML][HTML] Pancreatic beta cells synthesize neuropeptide Y and can rapidly release peptide co-transmitters

MD Whim - PloS one, 2011 - journals.plos.org
MD Whim
PloS one, 2011journals.plos.org
Background In addition to polypeptide hormones, pancreatic endocrine cells synthesize a
variety of bioactive molecules including classical transmitters and neuropeptides. While
these co-transmitters are thought to play a role in regulating hormone release little is known
about how their secretion is regulated. Here I investigate the synthesis and release of
neuropeptide Y from pancreatic beta cells. Methodology/Principal Findings NPY appears to
be an authentic co-transmitter in neonatal, but not adult, beta cells because (1) early in …
Background
In addition to polypeptide hormones, pancreatic endocrine cells synthesize a variety of bioactive molecules including classical transmitters and neuropeptides. While these co-transmitters are thought to play a role in regulating hormone release little is known about how their secretion is regulated. Here I investigate the synthesis and release of neuropeptide Y from pancreatic beta cells.
Methodology/Principal Findings
NPY appears to be an authentic co-transmitter in neonatal, but not adult, beta cells because (1) early in mouse post-natal development, many beta cells are NPY-immunoreactive whereas no staining is observed in beta cells from NPY knockout mice; (2) GFP-expressing islet cells from an NPY(GFP) transgenic mouse are insulin-ir; (3) single cell RT-PCR experiments confirm that the NPY(GFP) cells contain insulin mRNA, a marker of beta cells. The NPY-immunoreactivity previously reported in alpha and delta cells is therefore likely to be due to the presence of NPY-related peptides. INS-1 cells, a beta cell line, are also NPY-ir and contain NPY mRNA. Using the FMRFamide tagging technique, NPY secretion was monitored from INS-1 beta cells with high temporal resolution. Peptide release was evoked by brief depolarizations and was potentiated by activators of adenylate cyclase and protein kinase A. Following a transient depolarization, NPY-containing dense core granules fused with the cell membrane and discharged their contents within a few milliseconds.
Conclusions
These results indicate that after birth, NPY expression in pancreatic islets is restricted to neonatal beta cells. The presence of NPY suggests that peptide co-transmitters could mediate rapid paracrine or autocrine signaling within the endocrine pancreas. The FMRFamide tagging technique may be useful in studying the release of other putative islet co-transmitters in real time.
PLOS