title: Regulation of IPSP theta rhythm by muscarinic receptors and endocannabinoids in hippocampus.
abstract: Theta rhythms are behaviorally relevant electrical oscillations in the mammalian brain, particularly the hippocampus. In many cases, theta oscillations are shaped by inhibitory postsynaptic potentials (IPSPs) that are driven by glutamatergic and/or cholinergic inputs. Here we show that hippocampal theta rhythm IPSPs induced in the CA1 region by muscarinic acetylcholine receptors independent of all glutamate receptors can be briefly interrupted by action potential-induced, retrograde endocannabinoid release. Theta IPSPs can be recorded in CA1 pyramidal cell somata surgically isolated from CA3, subiculum, and even from their own apical dendrites. These results suggest that perisomatic-targeting interneurons whose output is subject to inhibition by endocannabinoids are the likely source of theta IPSPs. Interneurons having these properties include the cholecystokinin-containing cells. Simultaneous recordings from pyramidal cell pairs reveal synchronous theta-frequency IPSPs in neighboring pyramidal cells, suggesting that these IPSPs may help entrain or modulate small groups of pyramidal cells.
authors.affiliation: Department of Physiology, Program in Neuronscience, University of Maryland School of Medicine, Baltimore, 21201, USA.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Reich
authors.forename: Miranda A
authors.initials: MA
authors.lastname: Karson
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Karnup
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Jones
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Alger
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D063388:Endocannabinoids; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011976:Receptors, Muscarinic / Q000502:physiology*; D013057:Spectrum Analysis; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013826:Theta Rhythm / Q000187:drug effects; D013997:Time Factors; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D063385:Cannabinoid Receptor Modulators; D018679:Cholinergic Agonists; D063388:Endocannabinoids; D018691:Excitatory Amino Acid Antagonists; C114624:LY 341495; D010880:Piperidines; D011720:Pyrazoles; D011810:Quinoxalines; D011976:Receptors, Muscarinic; D014966:Xanthenes; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; C103505:AM 251; D008734:Methoxyhydroxyphenylglycol; D002217:Carbachol; C010117:3,4-dihydroxyphenylglycol