Pharmacological interference with glutamate re-uptake impairs long-term memory in the honeybee, Apis mellifera

The role of glutamate in the central nervous system of invertebrates is poo rly understood. In the present study we examined the effects of a glutamate transporter inhibitor, L-trans-2,4-pyrrolidine dicarboxylate (L-trans-2,4- PDC) on memory formation in the honeybee following a three-trial classical conditioning of the proboscis extension reflex (PER). Pre-training injectio ns of the drug have no effect on acquisition and short-term (1 h) memory, b ut impair long-term (24 h), associative olfactory memory in a dose-dependen t manner. This effect is transient and the amnesiac individuals can be re-t rained successfully 48 h after injections. Our results suggest that glutama tergic neurons in the honeybee brain, in particular those found in the mush room bodies (MBs), may be part of the circuitry involved in processing of l ong-term olfactory memory. Such a role for this neurotransmitter is consist ent with our previous results showing that glutamate and glutamate transpor ter(s) are localised in regions of the honeybee brain implicated in higher order processing. (C) 2000 Elsevier Science B.V: AII rights reserved.