title: Long-term plasticity in identified hippocampal GABAergic interneurons in the CA1 area in vivo.
abstract: Long-term plasticity is well documented in synapses between glutamatergic principal cells in the cortex both in vitro and in vivo. Long-term potentiation (LTP) and -depression (LTD) have also been reported in glutamatergic connections to hippocampal GABAergic interneurons expressing parvalbumin (PV+) or nitric oxide synthase (NOS+) in brain slices, but plasticity in these cells has not been tested in vivo. We investigated synaptically-evoked suprathreshold excitation of identified hippocampal neurons in the CA1 area of urethane-anaesthetized rats. Neurons were recorded extracellularly with glass microelectrodes, and labelled with neurobiotin for anatomical analyses. Single-shock electrical stimulation of afferents from the contralateral CA1 elicited postsynaptic action potentials with monosynaptic features showing short delay (9.95 ± 0.41 ms) and small jitter in 13 neurons through the commissural pathway. Theta-burst stimulation (TBS) generated LTP of the synaptically-evoked spike probability in pyramidal cells, and in a bistratified cell and two unidentified fast-spiking interneurons. On the contrary, PV+ basket cells and NOS+ ivy cells exhibited either LTD or LTP. An identified axo-axonic cell failed to show long-term change in its response to stimulation. Discharge of the cells did not explain whether LTP or LTD was generated. For the fast-spiking interneurons, as a group, no correlation was found between plasticity and local field potential oscillations (1-3 or 3-6 Hz components) recorded immediately prior to TBS. The results demonstrate activity-induced long-term plasticity in synaptic excitation of hippocampal PV+ and NOS+ interneurons in vivo. Physiological and pathological activity patterns in vivo may generate similar plasticity in these interneurons.
authors: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
authors: Petrina Yau-Pok
authors: PY
authors: Lau
authors: MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, OX1 3TH, UK.
authors: Linda
authors: L
authors: Katona
authors: MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, OX1 3TH, UK.
authors: Peter
authors: P
authors: Saghy
authors: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.|MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, OX1 3TH, UK.
authors: Kathryn
authors: K
authors: Newton
authors: MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, OX1 3TH, UK. peter.somogyi@pharm.ox.ac.uk.
authors: Peter
authors: P
authors: Somogyi
authors: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK. klamsa@bio.u-szeged.hu.|Department of Anatomy, Physiology and Neuroscience, University of Szeged, Közép fasor, Szeged, 6720, Hungary. klamsa@bio.u-szeged.hu.
authors: Karri P
authors: http://orcid.org/0000-0002-4609-1337
authors: KP
authors: Lamsa
mesh_terms: D000200:Action Potentials; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000502:physiology*; D004558:Electric Stimulation; D059330:GABAergic Neurons / Q000166:cytology / Q000502:physiology*; D007395:Interneurons / Q000166:cytology / Q000502:physiology*; D017774:Long-Term Potentiation; D036881:Long-Term Synaptic Depression; D008297:Male; D017207:Rats, Sprague-Dawley
keywords: Interneuron; Ivy cell; LTD; LTP; Oscillation; Parvalbumin