Interaction of long chain n-alkyl diamines with the NMDA receptor complex.

Long chain 1, omega-diamines with 8, 10, 12, 14 and 16 carbon atoms reduced the binding of [3H]MK 801 to rat hippocampal membranes with IC50 values of 333, 72, 16.5, 4.7 and 4.3 microM, respectively. In the presence of medium-effective concentrations of the diamines, the concentration response curve of the stimulation by the polyamine spermine was shifted to higher spermine concentrations, reaching similar maximal stimulation as in the absence of the diamines. In the case of 1,12-diaminododecane (N-12-N) and 1,14-diaminotetradecane (N-14-N), the extent of this shift was compatible with competitive antagonism of spermine. Inhibition of [3H]MK 801 binding by long chain diamines was sensitive to spermine, inhibition by N-12-N and N-14-N exhibited the highest sensitivities. Of all diamines tested, N-12-N and N-14-N seem to be the most likely candidates for inverse polyamine agonists.