The analgesic effect of electrical stimulation of the periaqueductal gray matter (PAG) was studied in mice selectively bred for high and low stress-induced analgesia (HA and LA lines, respectively). The current intensity required for stimulation-produced analgesia (SPA) in LA mice was 5 times that for HA mice. Naloxone produced a 4-fold increase of SPA threshold in HA mice, but was ineffective in LA mice. These findings suggest that the differential responsiveness of these two lines to the analgesic effect of stress reflects a more general genetic modification of the efficacy and mechanism of their pain-inhibitory systems.
Bibliographical noteFunding Information:
Supported by NIH Grant NS07628 and the Polish Academy of Sciences Project CPBP-04.01/6.13.
- Genetic difference
- Periaqueductal gray matter
- Stimulation-produced analgesia
- Swim-induced analgesia