Bidirectional synaptic plasticity at nociceptive afferents in the rat central amygdala.
Glutamatergic inputs arising from the parabrachial nucleus to neurons in the lateral sector of the central amygdala were studied in vitro. Tetanic stimulation of these inputs led to LTP that did not require activation of NMDA receptors or a rise of postsynaptic calcium. LTP was accompanied by a reduction in the paired-pulse ratio, indicating that LTP results from an increase in transmitter release probability. Activation of adenylyl cyclase with forskolin potentiated these inputs with a similar reduction in paired-pulse facilitation and occluded LTP induction. LTP was inhibited by the protein kinase A blocker H89. Low-frequency stimulation led to LTD that required activation of postsynaptic NMDA receptors and a rise in postsynaptic calcium. There was no change in paired-pulse facilitation with LTD. LTD was blocked by protein phosphatase blockers calyculin and okadaic acid. We conclude that parabrachial inputs to the lateral sector of the central amygdala show presynaptic LTP that requires activation of a presynaptic protein kinase A via a calcium-dependent adenylyl cyclase while LTD at the same synapses is postsynaptic and requires a rise in postsynaptic calcium and activation of protein phosphatase.
López de Armentia
Mikel
M
Queensland Brain Institute, University of Queensland, QLD 4072 Australia.
Sah
Pankaj
P
D000262:Adenylyl Cyclases / Q000378:metabolism; D000679:Amygdala / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D020013:Calcium Signaling; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D017774:Long-Term Potentiation; D036881:Long-Term Synaptic Depression; D009473:Neuronal Plasticity / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D010146:Pain / Q000378:metabolism / Q000503:physiopathology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D016194:Receptors, N-Methyl-D-Aspartate; D013449:Sulfonamides; D005576:Colforsin; D019319:Okadaic Acid; D018698:Glutamic Acid; D017868:Cyclic AMP-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D000262:Adenylyl Cyclases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide