Leptin fully suppresses acetylcholine-induced insulin secretion and is reversed by tolbutamide in isolated perfused chicken pancreas.
So far, there has been no evidence for any direct pancreatic effect of leptin in the chicken. The present study was aimed at detecting chicken leptin receptor (cOb-R) expression in isolated chicken islets of Langerhans and to examine the direct effect of leptin on insulin secretion after stimulation by acetylcholine (1 micro M) + glucose (14 mM) from isolated perfused chicken pancreas. We will show that i) full length cOb-R mRNA was expressed in isolated pancreatic islets of chickens, ii) recombinant chicken leptin (10 nM) or diazoxide (100 micro M) rapidly (within 2 min) and significantly suppressed insulin secretion induced by acetylcholine stimulation without any change in volume outflow rate, iii) tolbutamide (100 micro M) introduced 10 min after leptin and perfused for 10 min fully reversed the suppressive effect of leptin on pre-established acetylcholine-induced insulin release. In conclusion, we found that leptin has a profound inhibitory influence upon insulin secretion in perfused chicken pancreas. The results suggest that leptin inhibits insulin secretion by acting before or at the level of K ATP channels in chicken pancreatic beta-cells. Further studies are warranted to clarify the specific inhibitory mechanism.
Station de Recherches Avicoles, INRA, F37380 Nouzilly, France.
Y
Y
Benomar
N
N
Rideau
S
S
Crochet
M
M
Derouet
M
M
Taouis
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D018680:Cholinergic Antagonists / Q000494:pharmacology*; D017931:DNA Primers; D003981:Diazoxide / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D020738:Leptin / Q000494:pharmacology*; D010477:Perfusion; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000235:genetics*; D054411:Receptors, Leptin; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014044:Tolbutamide / Q000494:pharmacology*
D018680:Cholinergic Antagonists; D017931:DNA Primers; D007328:Insulin; D020738:Leptin; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D011994:Recombinant Proteins; D014044:Tolbutamide; D000109:Acetylcholine; D003981:Diazoxide