A short hairpin RNA (shRNA) for gene knockdown the genetic expression of NR1 subunit of N-methyl-D-aspartate (NMDA) receptor comprises a first fragment sharing homologous nucleotides among the NR1 subunit of NMDA receptor; a second fragment having complementary sequence to the first fragment; and a connecting fragment having any base in repeated arrangement, and connecting to the first and second fragments. Also, a method of treatment for pathological pain, by applying the shRNA described above to subcutaneous tissues of living organisms for gene knockdown the genetic expression of the NR1 subunit of NMDA receptor in hypoderm.