Role of the Serotonin Receptor Subtype 3A (5HT3A) in Pain in Female Rats

Serotonin (5HT) is a neurotransmitter and proinflammatory mediator that initiates pain signaling by binding 5HT receptors on sensory neurons. If 5HT receptors are co-expressed with the transient receptor potential vanilloid 1 (TRPV1), a pain-generating ion channel, then 5HT can exacerbate pain. Studies in male rats report the 5HT receptor subtype 3A (5HT3A) and TRPV1 are co-expressed on trigeminal sensory neurons that signal craniofacial pain, but no one has studied this in females. Because craniofacial pain occurs 2-4x more in women, examining pain mechanisms in female trigeminal sensory neurons is critical to advancing pain management. We used in situ hybridization to detect 5HT3A and TRPV1 mRNA and found co-minimal expression. We performed behavior testing and found that 5HT evoked pain behaviors in both sexes that was not decreased by blocking 5HT3A receptors. Our data indicate that the 5HT3A receptor does not play a major role in sex differences in craniofacial pain.

Presented at the 2021 Student Creative Arts and Research Symposium