The Journal of Neuroscience, December 14, 2005, 25(50):11614-11618; doi:10.1523/JNEUROSCI.3180-05.2005
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Focal and Temporal Release of Glutamate in the Mushroom Bodies Improves Olfactory Memory in Apis mellifera
Fernando Locatelli,1
Gesine Bundrock,1 and
Uli Müller1,2
1Freie Universität Berlin, Institut für Biologie, Neurobiologie, D-14195 Berlin, Germany, and 2Naturwissenschaftlich-Technische Fakultät III, Fachrichtung 8.3, Biowissenschaften, Zoologie/Physiologie, Universität des Saarlandes, D-66041 Saarbrücken, Germany
In contrast to vertebrates, the role of the neurotransmitter glutamate in learning and memory in insects has hardly been investigated. The reason is that a pharmacological characterization of insect glutamate receptors is still missing; furthermore, it is difficult to locally restrict pharmacological interventions. In this study, we overcome these problems by using locally and temporally defined photo-uncaging of glutamate to study its role in olfactory learning and memory formation in the honeybee, Apis mellifera. Uncaging glutamate in the mushroom bodies immediately after a weak training protocol induced a higher memory rate 2 d after training, mimicking the effect of a strong training protocol. Glutamate release before training does not facilitate memory formation, suggesting that glutamate mediates processes triggered by training and required for memory formation. Uncaging glutamate in the antennal lobes shows no effect on memory formation. These results provide the first direct evidence for a temporally and locally restricted function of glutamate in memory formation in honeybees and insects.
Key words: learning; memory; glutamate; caged glutamate; insects; Apis mellifera
Received July 29, 2005;
revised November 7, 2005;
accepted November 7, 2005.