d-Lactate inhibition of memory in a single trial discrimination avoidance task in the young chick

l-Lactate is a metabolite possibly able to meet some neuronal energy demands. However, a clear role for l-lactate in behaviour remains elusive. Administration of the inactive isomer d-lactate (1.75 mM; ic), immediately post-training, resulted in a persistent retention loss from 40 min post-training when used in conjuction with a single trial discrimination avoidance task designed for the young chick. Furthermore, 1 mM noradrenaline (ic) administered 20 min post-training overcame the retention loss induced by d-lactate. Although not directly demonstrated in the current study, it is plausible that d-lactate inhibited memory processing by competing with l-lactate for uptake into neurons. The time of onset of the retention loss induced by d-lactate is in accord with findings where the action of noradrenaline is inhibited. The successful challenge of d-lactate inhibition by a high concentration of noradrenaline may suggest a relationship by some unidentified mechanism.