Effect of cysteamine on cytosolic somatostatin binding sites in rabbit duodenal mucosa.
Administration of cysteamine in rabbits elicited a rapid depletion of both duodenal mucosa and plasma somatostatin. A significant reduction was observed within 5 min, returning toward control values by 150 min. The depletion of somatostatin was associated with an increase in the binding capacity and a decrease in the affinity of both high- and low-affinity binding sites present in cytosol of duodenal mucosa. Incubation of cytosolic fraction from control rabbits with 1 mM cysteamine did not modify somatostatin binding. Furthermore, addition of cysteamine at the time of binding assay did not affect the integrity of 125I-Tyr11-somatostatin. It is concluded that in vivo administration of cysteamine to rabbits depletes both duodenal mucosa and plasma somatostatin and leads to up-regulation of duodenal somatostatin binding sites.
D000818:Animals; D003543:Cysteamine / Q000494:pharmacology*; D003600:Cytosol / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D011817:Rabbits; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism; D017481:Receptors, Somatostatin; D013004:Somatostatin / Q000378:metabolism*
D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin; D013004:Somatostatin; D003543:Cysteamine