Characterization of sigma and phencyclidine binding sites in bovine adrenal medulla.

Abstract

The adrenal medullary sigma and phencyclidine (PCP) receptors have been characterized by radioligand binding studies in bovine adrenal medulla. Using the prototypic sigma receptor ligand ($\sp3$H) (+)SKF-10047, two binding components were revealed, firstly, a high affinity sigma site and secondary, a low affinity "PCP-like" binding site. Investigation of the sigma and PCP-like binding sites in the adrenal medulla using the highly selective sigma ( ($\sp3$H) 3(+)PPP) and phencyclidine receptor ( ($\sp3$H) TCP) ligands has demonstrated that these two binding sites share many similar features. The radioligands ($\sp3$H) 3(+)PPP and ($\sp3$H) TCP saturate a similar maximal population of receptors (B$\sb{\rm max}$ = 218-250 fmol/mg protein) and both are most potently displaced by sigma ligands. Slight differences in stereoselectivity suggest that the binding of ($\sp3$H) TCP and ($\sp3$H) 3(+)PPP may be to multiple subtypes of sigma receptors. Evidence accumulated suggests that a novel peptide from adrenal chromaffin cell granules namely, histogranin, may act as an endogenous ligand for one or both sigma subtypes defined in this study. (Abstract shortened by UMI.)