Administration of riluzole into the basolateral amygdala has an anxiolytic-like effect and enhances recognition memory in the rat
It is widely thought that inactivation of the glutamatergic system impairs recognition memory in rodents. However, we previously demonstrated that systemic administration of riluzole, which blocks the glutamatergic system, enhances recognition memory in the rat novel object recognition (NOR) test. The mechanisms underlying this paradoxical effect of riluzole on recognition memory remain unclear. In the present study, adult male Wistar rats were bilaterally cannulated in the basolateral amygdala (BLA) to examine the effects of intra-BLA administration of riluzole. We also compared the effects of riluzole with those of d-cycloserine, a partial agonist at the glycine binding site on the N-methyl-d-aspartate (NMDA) receptor. The BLA plays a critical role not only in recognition memory, but also in the regulation of anxiety. In the present study, intra-BLA administration of riluzole or d-cycloserine enhanced recognition memory in the NOR test. It was previously suggested that recognition memory can be strongly affected by the state of anxiety in rodents. Interestingly, intra-BLA administration of riluzole, but not d-cycloserine, produced a potent anxiolytic-like effect in the elevated plus-maze test. Thus, the enhancement of recognition memory by riluzole might be an indirect effect resulting from the anxiolytic-like action of the intra-BLA administration of the drug, and may not be directly related to inhibition of the glutamatergic system. Further studies are needed to clarify the mechanisms underlying the memory enhancing effect of riluzole.