Sex hormones appear to influence
levels of perceived pain. One gauge that
psychologists use to measure pain is the cold pressor test. During this test, subjects are asked to place
their left hand into a bucket of ice water and keep it submerged. Meanwhile, with their right hand they
manipulate a dial that rates their current level of pain. They are instructed to remove their hands
when the pain becomes unbearable. Scientists
have found that pain ratings and times until removal differ in conjunction with
varying hormone levels.
In normally menstruating women,
hormones fluctuate monthly. These
naturally varying concentrations of estradiol and progesterone found throughout
menstruation have both been found to affect perceived pain intensity. One group of scientists have found increased reports
of perceived pain using the cold pressor test during the late luteal (premenstrual)
phase when compared to the early follicular (when the ovary begins to prepare
to release the egg) phase of menstruation (Stening et al., 2007). There are higher levels of progesterone
released in the body during the follicular phase and higher estrogen levels
during the follicular phase. Therefore,
scientists think that these disparate hormone levels are what modulate the
differences in perceived pain. Another study
looked for a possible mechanism for this result. They found more μ-opioid receptor activity in
response to pain in women with higher levels of administrated estrogen (Honca
et al., 2013). These opioid receptors
are thought to increase pleasurable feelings and reduce pain. From this we may infer that estrogen can help
increase levels of endogenous opioids that can help reduce certain types of
pain, such as pain caused by ice water.
Graph showing the relationship between pain intensity in the cold
pressor test and serum concentrations of 17β-estradiol and progesterone, as
obtained from a general linear statistical model. At low concentrations of estradiol,
increasing concentrations of progesterone result in increasing VAS (pain rating)
of the cold pressor test. The model shows that high concentrations of both
estradiol and progesterone promote an antinociceptive effect, as illustrated by
the downward slope of the plane. (Stening et al., 2007)
However, things are likely more complicated
than fluctuating levels of one or two sex hormones. In figure 1 we observe that the relationship
between hormones and perceived pain change based on an interaction between the
two aforementioned hormones. Increased
levels of progesterone alone correlates with increased reports of pain, but estrogen
and progesterone together may lead to lower perceived levels of pain (Stening
et al., 2007). This interaction
complicates things much more than the aforementioned initial results that only
looked at sex hormones. These
relationships are even further complicated when you look at other factors that
influence pain. For example, it has been
found that women with normal menstrual cycles in committed relationships feel
pain at a higher level when they are closer to ovulation while similar women
not in committed relationships do not feel pain more when they are closer to
ovulation (Vigil et al., 2014). Not to mention, there are other hormones that influence how pain is perceived.
Clearly,
pain is a complicated phenomenon. Many
factors aside from hormone levels influence how we experience pain. These include amount of sleep, stress levels,
depression levels, genetic factors, personality types, and levels of fear. These include amount of sleep, stress levels, depression levels, genetic factors, personality types, and levels of fear. Anyway, with this knowledge we can plan
painful procedures such as surgeries at times to reduce pain as much as
possible.
Honca, M., Purtuloglu, T.,
Honca, T., Sizlan, A., Deniz, S., Kose, A., Horasanlı, E. (2013).
Effects of the menstrual cycle on injection pain due
to rocuronium. Journal
of Clinical
(5), 399-402.
doi:http://dx.doi.org/10.1016/j.jclinane.2013.02.007
Stening,
K., Eriksson, O., Wahren, L., Berg, G., Hammar, M., & Blomqvist, A. (2007).
Pain
sensations to the cold pressor test in normally menstruating
women: Comparison with
men and relation to menstrual phase and serum sex
steroid levels.American Journal of
(4), R1711-R1716.
Retrieved from
http://search.proquest.com/docview/68337546?accountid=7379
Vigil, J. M., Strenth, C.,
Trujillo, T., & Gangestad, S. W. (2014). Fluctuating Experimental Pain
Sensitivities
across the Menstrual Cycle Are Contingent on Women’s Romantic
Relationship
Status. Plos ONE, 9(3), 1-9. doi:10.1371/journal.pone.0091993
