ADP mediates inhibition of insulin secretion by activation of P2Y13 receptors in mice.
OBJECTIVE
To investigate the effects of extracellular purines on insulin secretion from mouse pancreatic islets.


METHODS
Mouse islets and beta cells were isolated and examined with mRNA real-time quantification, cAMP quantification and insulin and glucagon secretion. ATP release was measured in MIN6c4 cells. Insulin and glucagon secretion were measured in vivo after glucose injection.


RESULTS
Enzymatic removal of extracellular ATP at low glucose levels increased the secretion of both insulin and glucagon, while at high glucose levels insulin secretion was reduced and glucagon secretion was stimulated, indicating an autocrine effect of purines. In MIN6c4 cells it was shown that glucose does induce release of ATP into the extracellular space. Quantitative real-time PCR demonstrated the expression of the ADP receptors P2Y(1) and P2Y(13) in both intact mouse pancreatic islets and isolated beta cells. The stable ADP analogue 2-MeSADP had no effect on insulin secretion. However, co-incubation with the P2Y(1) antagonist MRS2179 inhibited insulin secretion, while co-incubation with the P2Y(13) antagonist MRS2211 stimulated insulin secretion, indicating that ADP acting via P2Y(1) stimulates insulin secretion, while signalling via P2Y(13) inhibits the secretion of insulin. P2Y(13) antagonism through MRS2211 per se increased the secretion of both insulin and glucagon at intermediate (8.3 mmol/l) and high (20 mmol/l) glucose levels, confirming an autocrine role for ADP. Administration of MRS2211 during glucose injection in vivo resulted in both increased secretion of insulin and reduced glucose levels.


CONCLUSIONS
In conclusion, ADP acting on the P2Y(13) receptors inhibits insulin release. An antagonist to P2Y(13) increases insulin release and could be evaluated for the treatment of diabetes.
Department of Cardiology, Lund University, Skane University Hospital, Lund, Sweden.
S
S
Amisten
S
S
Meidute-Abaraviciene
C
C
Tan
B
B
Olde
I
I
Lundquist
A
A
Salehi
D
D
Erlinge
D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001081:Apyrase / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D005934:Glucagon / Q000378:metabolism; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D016133:Polymerase Chain Reaction; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D013873:Thionucleotides / Q000494:pharmacology
D007328:Insulin; C546383:P2ry1 protein, mouse; C486689:P2ry13 protein, mouse; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D013873:Thionucleotides; C002480:methylthio-ADP; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005934:Glucagon; D000242:Cyclic AMP; D001081:Apyrase