Oxytocin-stimulated insulin release in a clonal beta-cell line RINm5F: involvement of phospholipase C-dependent and -independent pathways.
OBJECTIVE
To study the mechanisms underlying oxytocin (Oxy)-induced insulin release.


METHODS
In a clonal pancreatic beta-cell line, RINm5F cells.


RESULTS
Oxy increased insulin release and [Ca2+]i in a concentration-dependent manner. Oxy-induced insulin release was not altered by pretreatment with pertussis toxin (PT). U-73122 (2-8 mumol.L-1), a phospholipase C (PLC) inhibitor, concentration-dependently inhibited Oxy-induced increases in [Ca2+]i with IC50 value of 2.8 +/- 0.2 mumol.L-1. In addition, U-73122 diminished the Oxy-induced increase in intracellular concentration of inositol 1, 4, 5-triphosphate (IP3). U-73122 at 8 mumol.L-1 totally abolished the Oxy-induced increases in [Ca2+]i and IP3; however it reduced the Oxy-induced increase in insulin release only by 36% and 63% in the monolayer and suspended cell preparations, respectively.


CONCLUSIONS
Oxy increases insulin release through both PLC and non-PLC mediated signal transduction mechanisms.
Lee
B
B
Department of Veterinary Physiology and Pharmacology, Iowa State University, Ames 50011, USA.
Chen
T H
TH
Hsu
W H
WH
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007340:Insulinoma / Q000378:metabolism* / Q000473:pathology; D010121:Oxytocin / Q000494:pharmacology*; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000502:physiology
D004963:Estrenes; D007295:Inositol Phosphates; D007328:Insulin; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D010121:Oxytocin; C058097:inositol 1,3,4-trisphosphate; D010738:Type C Phospholipases; D002118:Calcium