Stress Exacerbates Orofacial Pain Behaviors to a Greater Degree in Female Rats

It is unclear if stress disproportionately affects orofacial pain, such as temporomandibular joint disorder pain, in women and men as the effects of stress on orofacial pain have only been study in males. Our objectives were (1) to detect differences in stress-exacerbated orofacial inflammatory pain in male and female rats and (2) to visualize underlying neuroplasticity in the trigeminal pain pathways. Rat cheekpads were inflamed prior to exposure to the forced swim stress test (psychological stressor) or sham conditions. Pain behaviors were measured using the von Frey method. Rats were then injected with a neuronal tracer into the inflamed cheekpad and postmortem tissues were collected. We report that stress increases pain behaviors in females and males, but females display higher and longer-lasting effects. Understanding sex differences in the effects of stress on orofacial pain will provide a better understanding of why orofacial pain disorders are 2-4x more prevalent in women.

Presented at the 2021 Student Creative Arts and Research Symposium