Sex, Hormones and Identity affect Nociceptive Expression (SHINE)Project Summary
It is often reported that females demonstrate lower pain thresholds and higher sensitivity than males in
experimental pain tests. However, “sex” and “gender” are often used interchangeably to describe these
differences, but genetic sex and gender identity are not always congruent. As a result, human subjects may be
categorized as male or female based upon genetic sex even if they do not identify as a man or woman,
respectively. Transgender (trans) men and women (TM and TW) are a minority group whose gender identity is
different than their genetic sex (as opposed to cisgender men and women; CM and CW). As a result, TM and
TW may experience stigma, prejudice and depression, putting them at greater risk for negative health outcomes
and impacted quality of life. Thus, this understudied community provides a unique opportunity to investigate the
role of gender identity (trans vs. cis), sex assigned at birth (male vs. female) and hormonal status (elevated
testosterone vs. elevated estrogen) on pain and well-being, while providing a better understanding of the needs
of the community. Specific aims of this study include: 1. To determine the impact of gender identity, sex assigned
at birth and hormone status on pain sensitivity. 2. To examine social and psychological factors to contribute to
pain sensitivity in our groups. 3.To quantify differences in immune cell populations and activity between our
groups. With the assistance of local community stakeholders we will recruit the following groups: CM, CW, TM+T
(currently taking exogenous testosterone), TW+E (exogenous estradiol), TM, and TW (n=20/group). We will use
quantitative sensory testing to assess sensitivity to cold, pressure, and heat via standardized protocols. Blood
samples will be taken for assessment of stress and reproductive hormone levels, immune cell populations and
stimulated cytokine release, as well as salivary samples to measure stress reactivity. Finally, questionnaires will
measure pain state, quality of life, voice quality of life, body image, appearance, self-reported health,
masculinity/femininity, community connectedness, gender role, sleep, depression, social support, adverse
childhood experiences and stigma. Together, this will be the first exploration of the impact of gender identity, sex
assigned at birth and hormonal status on quality of life, pain sensitivity and immune cell activity in trans
individuals. This investigation will also provide critical information with respect to the needs of this underserved
and critically understudied population.