Abstract
A series of 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) analogs were synthesized with the aim of developing a potent ligand for the N-methyl-D-aspartate glutamate receptor subtype. The piperidine moiety of TCP was substituted at the nitrogen position with aliphatic chains of different length or with various polar groups. A correlation between the decrease in the potency of displacement of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-im ine maleate (MK-801) binding from bovine cortex membranes and the increase of length or polarity of the aliphatic chain was observed. Isonitrile, isothiocyanate and isoselenocyanate groups were substituted at position 4 of the thiophene ring, and the relative binding affinity and alkylating potencies of the derivatized compounds were studied. Among this set of compounds, the one carrying an isothiocyanate group at position 4 of the thiophene ring of the N-ethyl analog of TCP yielded the most efficient alkylating agent, demonstrated by its ability to irreversibly block up to 80% of the [3H]MK-801 binding sites. This affinity ligand did not significantly affect other ligand binding sites of the same N-methyl-D-aspartate receptor complex or of other receptor systems, further demonstrating its functional specificity as a potent alkylating probe for the TCP/MK-801 recognition site. Studies with a radiolabeled adduct of this isothiocyanate N-ethyl derivative, however, indicate that a substantial level of nonspecific covalent incorporation into the membranes occurs at concentrations as low as 10 nM, thereby obscuring any possibility of detecting a specifically labeled protein species.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|