| 8719405 |
Popik P, Lewin A, Berrang B, Nowak G, Layer R, Skolnick P: [3H] 1-aminocyclopropanecarboxylic acid, a novel probe for strychnine- insensitive glycine receptors. J Neurosci. 1997 May 15;17(10):3392-400.
[3H] 1-Aminocyclopropanecarboxylic acid (ACPC) exhibits high affinity, specific binding to strychnine-insensitive glycine receptors. In extensively washed rat forebrain membranes, the specific binding of [3H] ACPC was optimal at 25 degrees C in the presence of 10 mM MgCl2. Comparable levels of specific [3H] ACPC binding were obtained using centrifugation and filtration for separation of bound from free radioligand. [3H] ACPC labels two sites with Kdl and Bmax1 values of 129 +/- 34 nM and 2.30 +/- 0.37 pmol/mg protein and Kd2 and Bmax2 values of 7.26 +/- 1.69 microM and 20.6 +/- 2.2 pmol/mg protein for the high and low affinity sites, respectively. The Kd of [3H] ACPC (66 nM) estimated under non-equilibrium conditions (koff = 8.91 +/- 0.78 x 10 (-3) s-1; kon = 1.35 x 10 (-4) nM-1 s-1) was similar to the value obtained for the high affinity site obtained by equilibrium binding. The Kd1 of [3H] ACPC is in good agreement with the previously reported Ki values of ACPC to inhibit the binding of other glycinergic ligands including [3H] glycine, [3H] 5,7-dichlorokynurenic acid (5,7-DCKA) and [3H] L-689,560 ((+/-)-4-(trans)-2-carboxy-5,7-dichloro-4- phenylaminocarbonylamino-1,2,3,4-tetrahydroquinoline). Moreover, the potencies of a series of glycine site ligands, including glycine. ACPC, 1-aminocyclobutanecarboxylic acid (ACBC), 5,7-DCKA, 7-chlorokynurenic acid (7-CKA), R (+)-3-amino-1-hydroxy-2- pyrrolidine (HA-966) and D-serine, to inhibit [3H] ACPC binding were highly correlated with their potencies to inhibit [3H] glycine and [3H] 5,7-DCKA binding (r2 = 0.98-0.51). These results demonstrate that [3H] ACPC is a useful tool for examining the neurochemical and pharmacological properties of strychnine-insensitive glycine receptors. |
93(1,1,3,3) |