Sex Related Pain Perception...

       Many differences exist between the male and female sex.  Among these is the perception of pain. Pain is said to have both physical and emotional components, which may explain the differences between men and women.  Studies have been conducted that produce possible theories for this occurrence. Some of these reasons are hormonal levels in the female body, and cognitive affective factors. Researchers have focused on the activity of one specific natural pain killer of the brain called the mu-opioid. This neurotransmitter system regulates the effects of endorphins as well as enkephalins. (Gavin, 2003: 2) These are among the chemicals that help suppress pain when signaled. These studies have brought up numerous questions about individualized treatment and medicine for people. Some other questions to consider include, will this change the way patients are treated for pain? But first we must consider what pain is and how it affects humans then zoom in on the differences between men and women.

       The process that occurs within the brain when someone is injured or experiencing pain starts when pain becomes threatening or significantly uncomfortable. Groups of cells within the brain release chemicals, called endorphins. These bind to receptors or nearby brain cells and regulate how the brain interprets pain-related signals those cells are sending to each other. This effect is called antinociception, because the transmitters suppress the pain response (Fillingim, 2000: 26). The opposite would be nociception, which is the perception of pain. Mu-opioids are found throughout the brain but particularly known to be involved in our physical and emotional responses to stressors, like pain. Thus, anything binding to these receptors, morphine, anesthetics, and endorphins, all suppress pain. (Gavin, 2003: 2)

        Researchers use brain imaging techniques to see how the brain controls our pain. Using technology where they could see chemical activity within the brain they found evidence that suggests sex hormones, like estrogen, as well as genes play a major role in how pain is perceived. (Kritz, 2000: 2) Estrogen levels that occur in a women’s menstrual cycle seems to regulate the brains natural ability to suppress pain. Studies show when levels are high brain pain killers respond more effectively but when low, the system does not work nearly as effectively. The idea is that estrogen acts as a protector and increases the number of available mu-opioid receptors.

       Previously, studies of pain and possible treatments were only occurring in animals but have recently branched into humans. In 1993 President Clinton signed the NIH Revitalization Act, requiring the inclusion of women in NIH research. Then in 1996 the NIH formed a Pain Research Consortium to study the implications of gender and sex in connection with pain. (Berkley, 1997: 4) At the conference, researchers suggested that sex differences in pain are substantial and argued specifically that women are more sensitive to pain. They stated that, women report pain more often and also report it at higher levels than men. Also, when men and women are exposed to a measured identical amount of pain, women will say that they are in pain sooner than men.

        The findings suggest that women can endure pain better during their monthly menstrual cycle when estrogen is high. The estrogen levels they are unable to block the feeling of pain and regulate the brain's ability to suppress pain. When the estrogen is high, the brain is more capable of releasing endorphins to help reduce the pain. When the estrogen levels are low, like during one's menstrual cycle pregnancy, the brain does not release endorphins efficiently to reduce pain. I also explains the increase in pain occurrence in women older than 45. In these women estrogen levels have dropped and statistics show that they are more prone to pain in the low back, migraines, and other joint paint such as arthritis. (Kritz, 2000: 3)

      Another study included 91 men and 52 women with cancer-related chronic pain. In this sample, no differences were found between the sexes in the various measures of pain. The University of Washington researchers concluded that in treating chronic pain, the sex of the patient is less important than their psychosocial characteristics such as coping ability, marital satisfaction, and the impact of outside life activities. (Fillingim, 2000: 25) These can be filed under cognitive affective factors of an individual. How to cope with pain and self-efficacy is considered the second reason for this major difference in pain experience.

    Researchers on pain differences in animals such as mice found that the female animals seem to be more sensitive to pain and don’t respond to pain relievers as well as males. However, the differences between males and females are not large. Unfortunately for science, research on a genetic basis for pain differences between men and women is unconvincing. (Kritz, 2003: 1) In addition, researchers believe that within gender, there are individual differences in feeling pain that are linked to undiscovered genes. Researchers at Johns Hopkins University and the National Institute on Drug Abuse located a gene that could be responsible for individual variations in pain sensitivity. It gene codes for the mu opiate receptor, which binds with endogenous painkillers such as endorphins. Receptors are found primarily in the thalamus, the cerebral cortex, the visual cortex, and the basal ganglia, but with a lot of individual variation. Researchers found that the mice with more active form of the gene had a greater number of mu opiate receptors in the brain and a higher pain tolerance. (Science News, 2003: 4)

      This study is interesting because it raises a lot of other questions about women and why we are more susceptible to pain. It gives us a grasp on why we might be experiencing more pain than males and how to go about reducing the pain. Women and men have men differences that set them apart. Will there ever be a way to make males and females equal? Currently, because the differences seem minimal when looking at incidences such as chronic pain, it is not enough to being with individualized medicine. Unfortunately, because the FDA and physicians want drugs that work for both men and women it poses a problem for many drug companies to produce drugs that treat pain as affectively in both sexes. Researchers are still trying to learn how much of the rise is sex-related and how much is instead tied to factors like health, age and personality.

Sources:
1) www.nih.org
2) Fillingim, Roger. Sex, Gender, and Pain: Women and Men Really Are Different. 2000, 4: 24-30
3) Kritz, Francesca. Not Feeling Each Other’s Pain. Washington Post.19 December 2006. Page HE01
4) Gavin, Kara. Pain and the Brain. University of Michigan Health System. 2003. 1-5
5) Berkley, Karen. Sex Differences in Pain. BBS Online. 1997. 1-33