Characterization of specific binding sites for [3H]-1,3-di-o-tolyl-guanidine (DTG) in the rat glioma cell line C6-BU-1
✍ Scribed by Andrea Georg; Arno Friedl
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 663 KB
- Volume
- 6
- Category
- Article
- ISSN
- 0894-1491
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✦ Synopsis
Abstract
The aim of the present study was to find out if a cell line of glial origin possesses sigma and/or phencyclidine (PCP) binding sites. Binding of [^3^H]1,3‐di‐o‐tolyl‐guanidine (DTG), a highly selective ligand for sigma binding sites, and of [^3^H]N‐[1‐(2‐thienyl)cyclohexyl] piperidine ([^3^H]TCP), a radioligand specific for PCP receptors, to C6‐BU‐1 glioma cells was investigated. Binding of [^3^H]DTG to C6‐BU‐1 cell membranes was reversible, saturable (B~max~ = 10.5 pmol/mg protein), and of high affinity (K~D~ = 26 nM). C6‐BU‐1 cells do not possess PCP receptors as indicated by negligible specific binding of [^3^H]TCP to C6‐BU‐1 cell membranes. Specific binding of [^3^H]DTG was reduced in the presence of Ca^2+^ and to a lesser extent by Mg^2+^ and to a lesser extent by Mg^2+^. The rank order of potency of various PCP and sigma ligands was DTG > (+)3‐[(3‐hydroxy‐phenyl)‐N‐n‐propyl‐piperidine] [(+)3‐PPP] > haloperidol > pentazocine > (‐)3‐PPP > PCP > metaphit > dextromethorphan > (‐)butaclamol > (+)butaclamol > (‐)N‐allylnormetazocine [(‐)SKF 10,047] > MK801 > (+)SKF 10,047 > ketamine. The drug specificity, confirmed by a reversed stereoselectivity for the benzomorphan opiate SKF 10,047, indicated that these sites correspond to a subtype of sigma binding sites, the so‐called sigma 2 binding site. Thus, the C6‐BU‐1 cell line is the first glial cell line demonstrated to have sigma 2 binding sites. © 1992 Wiley‐Liss, Inc.