ALTERATIONS IN NITRIC OXIDE-STIMULATED ENDOGENOUS ADP-RIBOSYLATION ASSOCIATED WITH LONG-TERM POTENTIATION IN RAT HIPPOCAMPUS

The present study examines the possible involvement of nitric oxide (N O)-stimulated endogenous ADP-ribosylation in long-term potentiation (L TP). LTP was induced in hippocampal slices by stimulation of Schaffer collateral inputs to the CA1 pyramidal neurons. Basal and sodium nitro prusside (SNP), which generates NO, stimulation of endogenous ADP-ribo sylation was then studied in CA1 subfields isolated from the slices. C ontrol slices received no treatment or were tetanized in the presence of amino-phosphonovaleric acid, an NMDA receptor antagonist that block s the development of LTP. SNP-stimulated ADP-ribosylation of endogenou s proteins was reduced by 40-70% in LTP slices relative to control sli ces. LTP was also associated with a small but significant reduction in basal ADP-ribosylation activity. The results demonstrate that the ind uction of LTP is associated with regulation of endogenous ADP-ribosyla tion and suggest a role for this type of covalent modification in some aspect of LTP.