Transient voltage-activated K+currents in central antennal lobe neurons: cell type-specific functional properties.
In this study we analyzed transient voltage-activated K+currents (IA) of projection neurons and local interneurons in the antennal lobe of the cockroachPeriplaneta americanaThe antennal lobe is the first synaptic processing station for olfactory information in insects. Local interneurons are crucial for computing olfactory information and form local synaptic connections exclusively in the antennal lobe, whereas a primary task of the projection neurons is the transfer of preprocessed olfactory information from the antennal lobe to higher order centers in the protocerebrum. The different physiological tasks of these neurons require specialized physiological and morphological neuronal phenotypes. We asked if and how the different physiological phenotypes are reflected in the functional properties ofIA, which is crucial for shaping intrinsic electrophysiological properties of neurons. Whole cell patch-clamp recordings from adult maleP. americanashowed that all their central antennal lobe neurons can generateIAThe current exhibited marked cell type-specific differences in voltage dependence of steady-state activation and inactivation, and differences in inactivation kinetics during sustained depolarization. Pharmacological experiments revealed thatIAin all neuron types was partially blocked by α-dendrotoxin and phrixotoxin-2, which are considered blockers with specificity for Shaker- and Shal-type channels, respectively. These findings suggest thatIAin each cell type is a mixed current generated by channels of both families. The functional role ofIAwas analyzed in experiments under current clamp, in which portions ofIAwere blocked by α-dendrotoxin or phrixotoxin-2. These experiments showed thatIAcontributes significantly to the intrinsic electrophysiological properties, such as the action potential waveform and membrane excitability.NEW & NOTEWORTHYIn the insect olfactory system, projection neurons and local interneurons have task-specific electrophysiological and morphological phenotypes. Voltage-activated potassium channels play a crucial role in shaping functional properties of these neurons. This study revealed marked cell type-specific differences in the biophysical properties of transient voltage-activated potassium currents in central antennal lobe neurons.
Biocenter, Institute for Zoology, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
Lars
L
Paeger
Biocenter, Institute for Zoology, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
Viktor
V
Bardos
Biocenter, Institute for Zoology, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany peter.kloppenburg@uni-koeln.de.
Peter
P
Kloppenburg
D000200:Action Potentials; D000818:Animals; D057506:Arthropod Antennae / Q000166:cytology / Q000502:physiology*; D001921:Brain / Q000166:cytology / Q000502:physiology; D002478:Cells, Cultured; D003058:Cockroaches; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism*
D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated
Periplaneta americana; glomerulus; local interneuron; olfaction; projection neuron