Axonal sorting of Kir3.3 defines a GABA-containing neuron in the CA3 region of rodent hippocampus.
Hippocampal interneurons comprise a heterogeneous group of locally acting GABAergic neurons. In addition to their variability in cotransmitter content and receptor profile, they express a variety of potassium channels that specify their individual properties. Here we describe a new type of large GABA-containing neuron in rodent hippocampus that is characterized by an axonal sorting of the potassium channel Kir3.3. The parent cell bodies of the Kir3.3-positive axons are located in CA3, as assessed by primary cultures derived from hippocampal subareas. At postnatal day 14 these neurons appear at the border between stratum oriens and stratum pyramidale of CA3, from where their axons pass through stratum pyramidale to join the mossy fiber tract. In adult hippocampus, high levels of Kir3.3 channel protein exist in axons that run with the mossy fiber tract. Kir3.3 and the vesicular GABA transporter could be identified in subpopulations of large synaptic terminals that probably derive from Kir3.3 neurons. Axonal sorting of Kir3.3 appears to be typical of a group of large inhibitory neurons, including Purkinje cells and a novel type of interneuron in CA3. Kir3.3 neurons might modulate the activity of CA3 circuitries and consequently memory processing in the hippocampus.
Grosse
Gisela
G
Institut für Anatomie der Charité, Humboldt-Universität zu Berlin, Schumannstrasse 20/21, 10117 Berlin, Germany.
Eulitz
Dirk
D
Thiele
Theodor
T
Pahner
Ingrid
I
Schröter
Sascha
S
Takamori
Shigeo
S
Grosse
Johannes
J
Wickman
Kevin
K
Tapp
Rosemarie
R
Veh
Rüdiger W
RW
Ottersen
Ole Petter
OP
Ahnert-Hilger
Gudrun
G
D000818:Animals; D001370:Axonal Transport / Q000502:physiology; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D005333:Fetus; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D050485:GABA Plasma Membrane Transport Proteins; D006624:Hippocampus / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D007395:Interneurons / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D009433:Neural Inhibition / Q000502:physiology; D027361:Organic Anion Transporters; D015221:Potassium Channels / Q000172:deficiency* / Q000235:genetics; D024661:Potassium Channels, Inwardly Rectifying; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D002352:Carrier Proteins; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D050485:GABA Plasma Membrane Transport Proteins; C497072:Kcnj9 protein, mouse; C497073:Kcnj9 protein, rat; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D027361:Organic Anion Transporters; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D005680:gamma-Aminobutyric Acid