Guanine nucleotide sensitivity of [125I]-Iodo NTyr somatostatin binding in rat adenohypophysis and cerebral cortex.
Specific [125I]-Iodo-NTyr somatostatin binding sites are present in adenohypophyseal and cerebral cortical membranes. Guanine nucleotides reduce the maximal binding capacity of adenohypophyseal binding sites without significantly affecting their apparent affinity. In pituitary as well as in cortex, GTP is the most potent nucleotide followed by GDP and guanylyl imidodiphosphate (GMP-PNP). The effect appears specific of guanine nucleotides since ATP, ADP and AMP are inactive on [125I]-Iodo-NTyr somatostatin binding. These results, showing the nucleotide sensitivity of [125I]-Iodo-NTyr somatostatin binding in pituitary and cerebral cortex, are compatible with a coupling of somatostatin receptors with adenylate cyclase.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D017481:Receptors, Somatostatin; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000378:metabolism
D006150:Guanine Nucleotides; D011956:Receptors, Cell Surface; D017481:Receptors, Somatostatin; D006153:Guanosine Diphosphate; D006165:Guanylyl Imidodiphosphate; D013004:Somatostatin; C034801:somatostatin, iodo-Tyr(1)-; D006160:Guanosine Triphosphate