Research May Explain Why Males and Females Experience Pain Differently
A study conducted by CBN faculty, Anne Murphy, and CBN graduate scholar, Dayna Loyd, both at Georgia State University (GSU), reports that anatomical and functional differences in the brain may explain gender differences in the experience of pain and the effects of certain drugs on pain.
The finding reported in the Journal of Comparative Neurology, is the first report of specific differences in the parts of the brain responsible for the transmission of pain sensations in the body. Along with a host of clinical evidence, this finding could lead to the development of differential treatments for pain in men versus women.
Pain has been described as the modern epidemic. More than 70 percent of adults will experience chronic pain at some time in their lives. Thus, the management of pain has become one of the highest priorities in health care. Chronic pain from inflammatory conditions such as arthritis and fibromyalgia are the most prevalent and pervasive forms of chronic pain.
Clinical evidence suggests that women are much more likely to experience chronic forms of pain than are men and that women report feeling more pain than men following various medical procedures.
Recent recommendations from the American Academy of Pain Medicine and the American Pain Society indicate that opioid drugs or "narcotics," such as morphine, are essential in the management of chronic pain. However, there is well-established clinical and nonclinical evidence that males and females do not respond the same to the effects of morphine. Specifically, females tend to request higher doses of morphine than males for pain relief following various medical procedures.
This study by Murphy and Loyd showed that male and female rodents are anatomically different in the area of the brain called the periaqueductal gray (PAG) and its projection to the spine, called the PAG-RVM (rostral ventral medulla) circuit, believed to be the main pain circuit in the brain-body experience of inflammatory pain and its treatment by opioid drugs. Specifically, females showed more PAG-RVM neurons than males.
The study also showed that the PAG-RVM circuit was significantly more activated by inflammatory pain in males than in females and that the opioid drug, morphine, reduced the response of this circuit to inflammatory pain to a greater degree in males versus females.
These results provide the first potential anatomical and functional explanation for gender differences in the experience of pain and responses to the drug morphine in the treatment of pain.
Given that morphine is currently the drug of choice for treating several types of post-operative pain, these results provide important details about how morphine might be used differently in females and males to achieve maximum pain relief.
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