Evidence that orexins A and B stimulate insulin secretion from rat pancreatic islets via both receptor subtypes.
Orexins are recently identified neuropeptides that appear to play a role in the regulation of energy homeostasis and arousal. They bind to and activate two closely related G protein-coupled receptors (OXR1 and OXR2), previously described as orphans. In this study we examined involvement of orexins in regulation of insulin secretion from rat pancreatic islets utilizing an in situ perfused pancreas and isolated pancreatic islet models. By means of RT-PCR we found that both OXR1 and OXR2 are expressed in rat pancreatic islets. Furthermore, the expression levels of OXR1 were higher than OXR2. In both experimental models applied, orexins A and B (1, 10 and 100 nmol/l) concentration dependently stimulated insulin secretion at two different glucose concentrations (6.66 or 26.4 mmol/l), with orexin A being more potent than orexin B. This study demonstrates that orexins A and B modulate insulin secretion in vitro.
Nowak
Krzysztof W
KW
Department of Animal Physiology and Biochemistry, August Cieszkowski University of Agriculture, 60-637 Poznan, Poland. kwnowak@owl.au.poznan.pl
Strowski
Mathias Z
MZ
Switonska
Malgorzata M
MM
Kaczmarek
Przemyslaw
P
Singh
Vandana
V
Fabis
Marzena
M
Mackowiak
Pawel
P
Nowak
Magdalena
M
Malendowicz
Ludwik K
LK
D000818:Animals; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D015870:Gene Expression; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D009479:Neuropeptides / Q000494:pharmacology*; D064446:Orexin Receptors; D000068797:Orexins; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide