The drug is less effective in female rats, and a new study shows why
Sex equality means nothing when it comes to pain relief.
Morphine is not very potent in female rats, and a new study helps explain why. In their midbrains, females have fewer of the receptors that sense the feel-good drug, rendering morphine “remarkably ineffective,” according to a report published December 24 in the Journal of Neuroscience.
Opioid-based narcotics, such as morphine and codeine, are some of the most widely prescribed drugs for human pain management. The drugs are detected by proteins in the brain called opioid receptors, which bind to the drugs and trigger pain relief. But earlier studies in humans and rats have suggested that when it comes to pain-fighting medications, males and females are not created equal.
Female rats are known to require twice the amount of morphine as males to get comparable pain relief, says study author Anne Murphy of Georgia State University in Atlanta. But much of the research on pain relief