DISTINCT SYNAPTIC LOCI OF CA 2+ /CALMODULIN DEPENDENT PROTEIN KINASE II NECESSARY FOR LONG-TERM POTENTIATION AND DEPRESSION. STANTON, PATRIC K. AND ALLYSON T. GAGE. Departments of Neuroscience and Neurology, Albert Einstein College of Medicine, Bronx, NY, 10461-1602.
APStracts 3:0107N, 1996.
SUMMARY AND CONCLUSIONS
1. Extracellular bath application of the selective Ca 2+ /calmodulin-dependent kinase II (CaMKII) inhibitor KN-62 to hippocampal slices in vitro blocked the induction of long-term depression (LTD) by low-frequency Schaffer collateral stimulation (1 Hz/15 min), at the same concentration as has been shown previously to prevent induction of long-term potentiation (LTP) at these synapses. 2. In contrast, postsynaptic intracellular infusion of KN-62 into single CA1 pyramidal neurons did not prevent induction of LTD, although it was quite effective in blocking LTP. 3. We conclude that there is a presynaptic CaMKII that must be activated to induce LTD, while postsynaptic CaMKII stimulation is needed to evoke LTP. 4. Bath application of KN-62 also blocked depotentiation by low frequency stimuli of previously-induced LTP, suggesting that induction of depotentiation and de novo LTD may require the same CaMKII- dependent presynaptic mechanisms. 

Received 15 April 1996; accepted in final form 22 May 1996.
APS Manuscript Number J307-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96