title: Target-selectivity of parvalbumin-positive interneurons in layer II of medial entorhinal cortex in normal and epileptic animals.
abstract: The medial entorhinal cortex layer II (MEClayerII ) is a brain region critical for spatial navigation and memory, and it also demonstrates a number of changes in patients with, and animal models of, temporal lobe epilepsy (TLE). Prior studies of GABAergic microcircuitry in MEClayerII revealed that cholecystokinin-containing basket cells (CCKBCs) select their targets on the basis of the long-range projection pattern of the postsynaptic principal cell. Specifically, CCKBCs largely avoid reelin-containing principal cells that form the perforant path to the ipsilateral dentate gyrus and preferentially innervate non-perforant path forming calbindin-containing principal cells. We investigated whether parvalbumin containing basket cells (PVBCs), the other major perisomatic targeting GABAergic cell population, demonstrate similar postsynaptic target selectivity as well. In addition, we tested the hypothesis that the functional or anatomic arrangement of circuit selectivity is disrupted in MEClayerII in chronic TLE, using the repeated low-dose kainate model in rats. In control animals, we found that PVBCs innervated both principal cell populations, but also had significant selectivity for calbindin-containing principal cells in MEClayerII . However, the magnitude of this preference was smaller than for CCKBCs. In addition, axonal tracing and paired recordings showed that individual PVBCs were capable of contacting both calbindin and reelin-containing principal cells. In chronically epileptic animals, we found that the intrinsic properties of the two principal cell populations, the GABAergic perisomatic bouton numbers, and selectivity of the CCKBCs and PVBCs remained remarkably constant in MEClayerII . However, miniature IPSC frequency was decreased in epilepsy, and paired recordings revealed the presence of direct excitatory connections between principal cells in the MEClayerII in epilepsy, which is unusual in normal adult MEClayerII . Taken together, these findings advance our knowledge about the organization of perisomatic inhibition both in control and in epileptic animals. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.
authors.forename: Caren
authors.initials: C
authors.lastname: Armstrong
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.
authors.forename: Jessica
authors.initials: J
authors.lastname: Wang
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.
authors.forename: Soo
authors.initials: S
authors.lastname: Yeun Lee
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.
authors.forename: John
authors.initials: J
authors.lastname: Broderick
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.
authors.forename: Marianne J
authors.initials: MJ
authors.lastname: Bezaire
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.
authors.forename: Sang-Hun
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Irvine Department of Anatomy & Neurobiology, University of California, Irvine, California.|Department of Neurosurgery, Stanford University, Palo Alto, CA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Soltesz
mesh_terms: D000818:Animals; D064026:Calbindins / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D002766:Cholecystokinin / Q000378:metabolism; D004195:Disease Models, Animal; D018728:Entorhinal Cortex / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism / Q000473:pathology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005260:Female; D053444:Inhibitory Postsynaptic Potentials; D007395:Interneurons / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D007608:Kainic Acid; D008297:Male; D055369:Miniature Postsynaptic Potentials; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D010320:Parvalbumins / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000473:pathology; D017208:Rats, Wistar; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000378:metabolism; D046509:Tissue Culture Techniques; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D064026:Calbindins; D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D010320:Parvalbumins; D000091042:Reelin Protein; C000717129:Reln protein, rat; D005680:gamma-Aminobutyric Acid; D002766:Cholecystokinin; D012697:Serine Endopeptidases; D007608:Kainic Acid
keywords: MEC; basket cell; calbindin; perisomatic inhibition; reelin