The selective antisense oligodeoxynucleotide probes against DOR and MOR reverse the Na
S-induced antinociception. Pre-treating rats with both the mismatched antisense oligodeoxynucleotides (panel A) and the κ opioid receptor antisense oligodeoxynucleotides (panel C) does not modify the H2S-induced decrease of the AWR score, confirming that KOR does not cause any change on the Na2S-induced analgesia. In contrast, oligodeoxynucleotide probes against DOR and MOR reverse the antinociception caused by Na2S (panel B and D respectively). Data are mean ± SEM of 5 rats. *p < 0.05 versus CRD.