Mechanistic investigation of N,N-diethyl-4-(phenyl-piperidin-4-ylidenemethyl)-benzamide-induced insulin depletion in the rat and RINm5F cells.
These studies describe the effect of N,N-diethyl-4-(phenyl-piperidin-4-ylidenemethyl)-benzamide (AR-M100390), a delta-opioid agonist, on the pancreas and its mechanisms for pancreatic toxicity. Rats were treated with 5, 100, and 600 micromol/kg of AR-M100390 for 3 and/or 7 days; another group of rats treated with 600 micromol/kg of compound were allowed to recover for 14 days. AR-M100390 (600 micromol/kg) caused vacuolation in the beta-cell of the rat pancreas that was associated with depletion of insulin and hyperglycemia after 7 days of dosing. The loss of insulin by AR-M100390 was due to specific inhibition of rat insulin2 mRNA transcription in vivo. Insulin depletion and hyperglycemia were reversible. The effects of AR-M100390 in rats were reproduced in the rat pancreatic beta-cell line RINm5F, where it inhibited intracellular insulin content and secretion without affecting cell survival. Loss of insulin in vitro was also a result of specific inhibition of insulin2 mRNA transcription and was reversible. Pretreatment of cells with the delta-opioid antagonist naltrindole or pertussis toxin did not reverse loss of insulin in AR-M100390-treated cells suggesting that the effects were not mediated by the delta-opioid receptor. AR-M100390 inhibited KCl-mediated calcium mobilization in RINm5F cells, suggesting that L-type calcium channels found in these cells and in pancreatic beta-cells may partially play a role in the inhibition of insulin secretion by this compound. In summary, the in vitro and in vivo studies suggest that inhibition of insulin by AR-M100390 is due to a combination of inhibition of insulin synthesis and/or release.
Otieno
Monicah A
MA
Safety Assessment US, AstraZeneca Pharmaceuticals, Wilmington, Delaware 19850, USA. monicah.otieno@bms.com
Bavuso
Nicole
N
Milano
Joseph
J
Foster-Brown
Linda
L
Bui
Khanh-Hui
KH
Li
Yan
Y
Hudzik
Thomas
T
Wescott
Debra
D
Louden
Calvert
C
Dyroff
Martin
M
Pognan
François
F
D000818:Animals; D001549:Benzamides / Q000633:toxicity*; D001786:Blood Glucose / Q000032:analysis; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000502:physiology; D002478:Cells, Cultured; D003501:Cyclizine / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D010179:Pancreas / Q000187:drug effects* / Q000378:metabolism; D010880:Piperidines / Q000633:toxicity*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D017465:Receptors, Opioid, delta / Q000819:agonists*
D001549:Benzamides; D001786:Blood Glucose; D020746:Calcium Channels, L-Type; D007328:Insulin; C415566:N,N-diethyl-4-(phenylpiperidin-4-ylidenemethyl)benzamide; D010880:Piperidines; D012333:RNA, Messenger; D017465:Receptors, Opioid, delta; D003501:Cyclizine; D002118:Calcium