Characterization and localization of a novel neuroreceptor for the peptide sarafotoxin

• Published in: Biochemical and biophysical research communications Vol. 157; no. 3; p. 1104
• Main Authors: Ambar, I, Kloog, Y, Kochva, E, Wollberg, Z, Bdolah, A, Oron, U, Sokolovsky, M
• Format: Journal Article
• Language: English
• Published: United States 30-12-1988
• Subjects: Animals; Brain Chemistry; Brain Stem - analysis; Cerebellum - analysis; Cerebral Cortex - analysis; Hippocampus - analysis; Hypothalamus - analysis; Iodine Radioisotopes; Male; Olfactory Bulb - analysis; Rats; Receptors, Cholinergic - analysis; Receptors, Peptide; Thalamus - analysis; Tissue Distribution; Viper Venoms - metabolism
• ISSN: 0006-291X
• DOI: 10.1016/S0006-291X(88)80987-2

We have recently shown that the rat atrium and brain contain specific high affinity receptors for the novel snake vasoconstrictor peptide sarafotoxin-b (SRTXb), and demonstrated toxin-induced phosphoinositide hydrolysis. Here we report on the characteristics of 125I-SRTXb receptors and their regional distribution in rat brain. 125I-SRTX receptors in the rat brain bind the toxin rapidly and with high affinity. The binding was not inhibited by ligands of known neurotransmitter receptor and ion channels. 125I-SRTX receptors have a distinctive regional distribution. The highest densities were observed in the cerebellum, thalamus and hypothalamus (850, 550 and 450 fmol/mg protein, respectively) and the lowest densities in the caudate and cerebral cortex (82 and 62 fmol/mg protein, respectively). Taken together our results suggest that mammalian brains contain a hitherto undetected neuroreceptor that may operate in neurotransmission with a "SRTX-like" brain peptide, similar to the SRTX homologous vasoconstrictor peptide of the mammalian endothelium endothelin.