A ROLE FOR ADENOSINE IN THE REGULATION OF LONG-TERM DEPRESSION IN THEADULT-RAT HIPPOCAMPUS IN-VITRO

We describe how endogenous adenosine can prevent the induction of homo synaptic long-term depression (LTD) in the CA1 region of slices of adu lt rat hippocampus. Neither of two consecutive periods of prolonged lo w frequency stimulation (LFS; 1 Hz, 900 stimuli) of the Schaffer colla teral-commissural fibres resulted in the induction of LTD in the CA1 r egion of hippocampal slices from adult (8-30 week) animals. However, i n the presence of adenosine deaminase or the selective adenosine A(1) receptor antagonist, 1,3-dipropyl-8-cyclopentyl-xanthine (DPCPX), LTD was induced by each of the first and second of two periods of LFS. The first period of LFS did not, but the second period of LFS did, induce LTD in the presence of DPCPX and the NMDA receptor antagonist, D-2-am ino-5-phosphonopentanoate (AP5). The present results show that A(1) re ceptor activation by endogenous adenosine can prevent the induction of LTD in the adult hippocampus. (C) 1997 Elsevier Science Ireland Ltd.