Cyclic AMP mediates a presynaptic form of LTP at cerebellar parallel fiber synapses.
The N-methyl-D-aspartate receptor-independent form of long-term potentiation (LTP) at hippocampal mossy fiber synapses requires presynaptic Ca(2+)-dependent activation of adenylyl cyclase. To determine whether this form of LTP might occur at other synapses, we examined cerebellar parallel fibers that, like hippocampal mossy fiber synapses, express high levels of the Ca2+/calmodulin-sensitive adenylyl cyclase I. Repetitive stimulation of parallel fibers caused a long-lasting increase in synaptic strength that was associated with a decrease in paired-pulse facilitation. Blockade of glutamate receptors did not prevent LTP induction, nor did loading of Purkinje cells with a Ca2+ chelator. LTP was occluded by forskolin-induced potentiation and blocked by the protein kinase A inhibitor Rp-8-CPT-cAMPS. These findings suggest that parallel fiber synapses express a form of LTP that is dependent on the activation of a presynaptic adenylyl cyclase and is indistinguishable from LTP at hippocampal mossy fiber synapses.
Salin
P A
PA
Department of Cellular and Molecular Pharmacology, University of California, San Francisco 94143-0450, USA.
Malenka
R C
RC
Nicoll
R A
RA
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002531:Cerebellum / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology*; D051381:Rats; D013569:Synapses / Q000502:physiology*; D013873:Thionucleotides / Q000494:pharmacology
D002147:Calmodulin; D004791:Enzyme Inhibitors; D013873:Thionucleotides; D005576:Colforsin; C016957:adenosine-3',5'-cyclic phosphorothioate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D002118:Calcium