We have recently demonstrated that local injection of glutamate transporter activator riluzole (RIL) and gabapentin (GBP) into the locus coeruleus activated noradrenergic neurons via glutamate signalling and resulting descending pain inhibition in rats, indicating that both RIL and GBP may share common mechanisms in astrocytes. In the present study, we examined the effects of RIL and GBP on glutamate uptake/release and glutamate-induced Ca²⁺ response in cultured astrocytes. Pre-treatment with RIL or GBP significantly increased glutamate uptake which was completely blocked by a non-selective glutamate transporter blocker, DL-TBOA. The enhancement of glutamate-induced intracellular Ca²⁺ response by RIL or GBP was blocked by the DL-TBOA and an inhibitor of Na⁺/Ca²⁺ exchanger, KB-R7943. Glutamate release from cultured astrocytes significantly increased in the presence of RIL and GBP. These results suggest that RIL and GBP enhance Na⁺-glutamate co-transport through glutamate transporters, and subsequent Ca²⁺ influx via the reverse mode of Na⁺/Ca²⁺ exchange enhances glutamate-induced glutamate release in astrocytes. The present study also suggests that GBP have a novel target of action in astrocytes other than α₂δ subunits.