Role of histamine as a putative inhibitory transmitter in the honeybee antennal lobe.
BACKGROUND
Odors are represented by specific spatio-temporal activity patterns in the olfactory bulb of vertebrates and its insect analogue, the antennal lobe. In honeybees inhibitory circuits in the AL are involved in the processing of odors to shape afferent odor responses. GABA is known as an inhibitory transmitter in the antennal lobe, but not all interneurons are GABAergic. Therefore we sought to analyze the functional role of the inhibitory transmitter histamine for the processing of odors in the honeybee AL.


RESULTS
We optically recorded the representation of odors before, during and after histamine application at the input level (estimated from a compound signal), and at the output level (by selectively measuring the projection neurons). For both, histamine led to a strong and reversible reduction of odor-evoked responses.


CONCLUSIONS
We propose that histamine, in addition to GABA, acts as an inhibitory transmitter in the honeybee AL and is therefore likely to play a role in odor processing.
Sachse
Silke
S
Institut für Biologie-Neurobiologie, Freie Universität Berlin, Königin-Luise Str, 28-30, D-14195 Berlin, Germany. ssachse@ice.mpg.de
Peele
Philipp
P
Silbering
Ana F
AF
Gühmann
Martin
M
Galizia
C Giovanni
CG