Oxytocin-stimulated insulin release in a clonal beta-cell line RINm5F: involvement of phospholipase C-dependent and -independent pathways
Lee, B.; Chen, T.H.; Hsu, W.H.
Zhongguo Yao Li Xue Bao 17(5): 390-394
1996
ISSN/ISBN: 0253-9756 PMID: 9863156 Document Number: 465723
AIM: 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 (Ca-2+)-i in a concentration-dependent manner. Oxy-induced insulin release was not altered by pretreatment with pertussis toxin (PT). U-73122 (2-8 mu-mol cntdot L-1), a phospholipase C (PLC) inhibitor, concentration-dependently inhibited Oxy-induced increases in (Ca-2+)-i with IC-50 value of 2.8 +- 0. 2 mu-mol cntdot L-1. In addition, U-73122 diminished the Oxy-induced increase in intracellular concentration of inositol 1, 4, 5-trisphosphate (IP-3). U-73122 at 8 mu-mol cntdot L-1 total ly abolished the Oxy-induced increases in (Ca-2+)-i and IP-3; however it reduced the Oxy-induced increase in insulin release only by 36% and 63% in the monolayer and suspended cell preparations, respectively. CONCLUSION: Oxy increases insulin release through both PLC and non-PLC mediated signal transduction mechanisms.