Antisense mapping involved designing antisense oligodeoxynucleotides (DNA) of approximately 20–25 bases that targeted the specific indicated exons were administered either supraspinally or spinally and their effect on analgesia determined. Compiled from the literature (Rossi et al., 1994a, 1995a,b; Kolesnikov et al., 1996b; Pan et al., 1999; Pasternak and Pan, 2000; Pasternak, 2001; Abbadie et al., 2002).