Effect of D-serine on mechanical nociceptive threshold and anxiety-like behavior at 28 days after PSNL. Ninety minutes after D-serine treatment, MWT (A), EPM (B), and OFT (C and D) were examined. The decreased MWT induced by PSNL was not attenuated by D-serine treatment (A). The percentage of time spent in the open arm as detected by the EPM test among the different groups (B). The percentage of time spent in the central zone as detected by the OFT among the different groups (C). The total number of squares crossed in the open field (D). *P <0.05 PSNL + Vehicle compared with Control + Vehicle, Control + D-serine and PSNL + D-serine groups. ***p < 0.001 PSNL + Vehicle and PSNL+ D-serine compared with Control + Vehicle and Control + D-serine groups.