New specific radioligand for one subpopulation of brain somatostatin receptors

Life Sci. 1985 May 13;36(19):1829-36. doi: 10.1016/0024-3205(85)90155-9.


Cyclic octapeptide analogues of somatostatin (SS) like SMS 201-995 [H-(D) Phe-Cys-Phe-(D) Trp-Lys-Thr-Cys-Thr(ol)] or its Tyr3-derivative 204-090, displaced [125I-Tyr11]-SS 100% from pancreatic membranes but only 62-75% from brain membranes; the remaining sites were displaced by SS. These data indicate that some mini-somatostatins bind to a subpopulation of SS receptors in rat brain. The iodinated Tyr3-derivative (125I-204-090) can be considered a selective radioligand for one rat brain SS receptor subpopulation: It shows saturable and high affinity binding (KD = 0.29 nM; Bmax = 350 fmoles/mg protein) to rat cortex. The pharmacological properties of 125I-204-090 binding sites are similar to those of [125I-Tyr11]-SS sites. Distribution of these sites correspond to SS receptor-rich areas such as cortex, hippocampus, striatum, pituitary, pancreatic beta-cell. SS as well as SMS 201-995 bind to these sites with high affinity. The stability and high specific vs non-specific binding ratio makes 204-090 a radioligand of choice to measure this SS receptor subpopulation in CNS but also the SS receptors in pituitary and pancreas.

MeSH terms

  • Animals
  • Binding, Competitive
  • Brain / metabolism*
  • Cerebral Cortex / metabolism
  • Hippocampus / metabolism
  • In Vitro Techniques
  • Iodine Radioisotopes
  • Octreotide
  • Pancreas / metabolism
  • Radioligand Assay
  • Rats
  • Receptors, Cell Surface / analysis*
  • Receptors, Somatostatin
  • Somatostatin / analogs & derivatives
  • Somatostatin / metabolism


  • Iodine Radioisotopes
  • Receptors, Cell Surface
  • Receptors, Somatostatin
  • 3-Tyr-octreotide
  • Somatostatin
  • somatostatin, Tyr(11)-
  • Octreotide