Swimming-induced analgesia was studied in 4 strains of mice differing in central opiate receptor density: C57BL/6By (C57). BALB/cBy (BALB/c). CXBK and CXBH. The degree of 'swim analgesia' significantly differed among strains in the order CXBH > BALB/c = C57 > CXBK. This order positively correlates with known differences in opiate receptor density in these strains. Naloxone reversed the analgesic effect of swimming in CXBH, C57 and BALB/c, but was ineffective in opiate receptor-deficient CXBK mice. These results suggest that genetic differences in central opiate receptor density influence the analgesic response to stressful stimuli.
Bibliographical noteFunding Information:
This study was supported by NIH Grant NS-07628 and by a gift from the David H. Murdock Foundation for Advanced Brain Studies.
- Genetic difference
- Opiate receptor
- Stress-induced analgesia