Biochemical and pharmacological characterization of somatostatin receptors in rat brain.
We have characterized specific receptors for tetradecapeptide somatostatin (SS-14) of rat brain using 125I-labeled Tyr11-SS-14([125I-Tyr11]SS-14) as radioligand. [125I-Tyr11]SS-14 binding was sensitive to time, pH, temperature and ionic strength of the buffer, and was optimal in 50mM HEPES/KOH buffer, pH 7.5, at 25 degrees C for 60 minutes. Scatchard analysis indicated that the rat forebrain membranes had a single binding site with an apparent dissociation constant (Kd) of 0.522 +/- 0.044 nM and maximum binding capacity (Bmax) was 233 +/- 37 fmol/mg protein (mean +/- SEM). Ca2+, Mg2+, Mn2+ and Co2+ had a significant effect on the specific binding, which indicates that these metal ions might affect somatostatin receptor activity in the brain. Among CNS acting drugs, Ca2+ antagonists, antischizophrenic drugs, antidepressants and anticholinergic drugs had relative effects on [125I-Tyr11]SS-14 bindings to rat cerebral cortex membranes.
Sato
H
H
Third Department of Internal Medicine, Okayama University Medical School, Japan.
Ota
Z
Z
Ogawa
N
N
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D017481:Receptors, Somatostatin; D013347:Subcellular Fractions / Q000187:drug effects; D013570:Synaptic Membranes / Q000187:drug effects; D013696:Temperature
D018377:Neurotransmitter Agents; D011480:Protease Inhibitors; D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin