Peripheral benzodiazepine receptors in isolated human pancreatic islets

✍ Scribed by Laura Giusti; Piero Marchetti; Letizia Trincavelli; Roberto Lupi; Claudia Martini; Antonio Lucacchini; Silvia Del Guerra; Cristina Tellini; Mario Carmellini; Renzo Navalesi

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 97 KB
• Volume: 64
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(199702)64:2<273::aid-jcb10>3.0.co;2-k

✦ Synopsis

Peripheral benzodiazepine receptors have been shown in some endocrine tissues, namely the testis, the adrenal gland, and the pituitary gland. In this work we evaluated whether peripheral benzodiazepine receptors can be found in the purified human pancreatic islets and whether they may have a role in insulin release. Binding of the isoquinoline compound [3H]1-(2-chlorophenyl-N-methyl-1-methyl-propyl)-3- isoquinolinecarboxamide (13H]PK-11195) a specific ligand of peripheral benzodiazepine receptors, to cellular membranes was saturable and Scatchard's analysis of the saturation curve demonstrated the presence of a single population of binding sites, with an affinity constant value of 9.20 +/- 0.80 nM and a maximum number of binding sites value of 8913 +/- 750 fmol/mg of proteins. PK-11195 and 7-chloro-1,3-dihydro-1-methyl-5-(p-chlorophenyl)-2H-1,4- benzodiazepine-2-on (Ro 5-4864) significantly potentiated insulin secretion from freshly isolated human islets at 3.3 mM glucose. These results show the presence of peripheral benzodiazepine receptors in purified human pancreatic islets and suggest their role in the mechanisms of insulin release.