Evidence for a role of GABA- and glutamate-gated chloride channels in olfactory memory

In the honeybee, we investigated the role of transmissions mediated by GABA-gated chloride channels and glutamate-gated chloride channels (GluCls) of the mushroom bodies (MBs) on olfactory learning using a single-trial olfactory conditioning paradigm. The GABAergic antagonist picrotoxin (PTX) or the GluCl antagonist l-trans-pyrrolidine-2,4-dicarboxylic acid (l-trans-PDC) was injected alone or in combination into the α-lobes of MBs. PTX impaired early long-term olfactory memory when injected before conditioning or before testing. l-trans-PDC alone induced no significant effect on learning and memory but induced a less specific response to the conditioned odor. When injected before PTX, l-trans-PDC was able to modulate PTX effects. These results emphasize the role of MB GABA-gated chloride channels in consolidation processes and strongly support that GluCls are involved in the perception of the conditioned stimulus.

► We examine inhibitory neurotransmission in mushroom bodies. ► PTX impairs early long-term memory because GABA transmission is blocked but not glutamate transmission. ► l-trans-PDC alone fails to impair early long-term memory. ► When injected before PTX, l-trans-PDC is able to modulate PTX effects.