Sex differences in the impact of pain, morphine administration and morphine withdrawal on quality of life in rats.

The disruptive effects of pain on quality of life are greater in men than in women, but the disruptive effects of opioid administration and withdrawal tend to be greater in women. These sex differences in pain, acute opioid effects, and opioid withdrawal tend to be opposite to sex differences reported in laboratory rats. We hypothesized that sex differences in humans and rats would more closely align if animal research measured quality of life as opposed to traditional evoked behaviors of pain (e.

Morphine restores and naloxone-precipitated withdrawal depresses wheel running in rats with hindpaw inflammation.

Opioids such as morphine are the most effective treatment for pain, but termination of opioid use can produce severe withdrawal symptoms. The present study models this process by using home cage wheel running to assess well-being as a result of pain, morphine analgesia, and opioid withdrawal. Injection of CFA into the right hindpaw caused a dramatic decrease in wheel running and body weight.