Abstract
Binding of 1-[1-(2-[3H]thienyl)cyclohexyl]piperidine ([3H]TCP) to mouse brain and spinal cord membranes was studied using compounds selective for the NMDA-coupled 1-(1-pnenylcyclohexyl)piperidine (PCP) and/or σ recognition sites. In both tissues, [3H]TCP labeled two populations of binding sites. Density of the low-affinity sites was approximately the same in both tissues, but the population of the high-affinity [3H]TCP sites was three times bigger in the brain than in the spinal cord. Self- and cross-displacement studies showed that the high-affinity [3H]TCP binding sites could be identical with NMDA receptor-coupled PCP sites, whereas the low-affinity [3H]TCP sites may be associated with σ binding sites in both tissues. The NMDA-coupled PCP sites labeled in the presence of 6.25 nM [3H]TCP constituted a much higher percentage of the total binding in the brain (75%) than in the spinal cord (44%). Consistent with this, reintroduction of glycine and glutamate significantly increased, but DA antagonists significantly inhibited [3H]-TCP binding in the brain but not in the spinal cord. Together, these data suggest that a large component of [3H]TCP-labeled binding sites in the spinal cord may be associated with σ but not the NMDA receptor-coupled PCP sites.
Original language | English (US) |
---|---|
Pages (from-to) | 1757-1765 |
Number of pages | 9 |
Journal | Journal of Neurochemistry |
Volume | 63 |
Issue number | 5 |
State | Published - Nov 1994 |
Keywords
- 1-[1-(2-[H]thienyl)cyclohexyl]-piperidine binding
- Brain
- MK-801
- NMDA
- Spinal cord
- σ Sites