Inhibition of synaptic transmission by neuropeptide Y in rat hippocampal area CA1: modulation of presynaptic Ca2+ entry.
Neuropeptide Y (NPY) agonists inhibit glutamate release by a presynaptic action at the CA3-CA1 synapse of rat hippocampus. We have examined the relationship between [Capre]t via presynaptic, voltage-dependent calcium channels (VDCCs), measured optically by using the fluorescent calcium indicator fura-2, and transmitter release, measured electrophysiologically. Activation of presynaptic NPY Y2 receptors reduced [Capre]t and thereby inhibited synaptic transmission. Multiple calcium channels are involved in synaptic transmission at this synapse. Activation of Y2 receptors inhibits N-type, P/Q-type, and unidentified presynaptic VDCCs. The inhibition of each of these calcium channel types contributes to the reduction of [Capre]t by Y2 receptors. Activation of adenosine receptors fully occluded the inhibition of presynaptic calcium influx by Y2 receptors but not the inhibition by GABAB receptors, suggesting a convergent action for Y2 and adenosine receptors, probably by coupling to the same G-protein.
Qian
J
J
Division of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA.
Colmers
W F
WF
Saggau
P
P
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000145:classification / Q000502:physiology*; D020864:Calcium Channels, N-Type; D004558:Electric Stimulation; D019204:GTP-Binding Proteins / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects*; D015640:Ion Channel Gating / Q000187:drug effects; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D008959:Models, Neurological; D009419:Nerve Tissue Proteins / Q000187:drug effects* / Q000502:physiology; D009478:Neuropeptide Y / Q000494:pharmacology*; D010446:Peptide Fragments; D019894:Peptide YY / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018080:Receptors, GABA-B / Q000187:drug effects / Q000502:physiology; D017476:Receptors, Neuropeptide Y / Q000187:drug effects* / Q000502:physiology; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D013111:Spider Venoms / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA
D000241:Adenosine; D001418:Baclofen; D002118:Calcium; D015220:Calcium Channels; D020864:Calcium Channels, N-Type; D019204:GTP-Binding Proteins; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D010446:Peptide Fragments; D019894:Peptide YY; D010455:Peptides; D018080:Receptors, GABA-B; D017476:Receptors, Neuropeptide Y; D018047:Receptors, Purinergic P1; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA; C095889:neuropeptide Y2 receptor; C053157:omega-conotoxin receptor; C061785:peptide YY (3-36)