Sex hormones drive neuron subtype-specific changes in neural activity

• Talha Dorez, Biological Sciences, University of Delaware

• Austin Keeler, Department of Biological Sciences, University of Delaware

Sex hormones influence pain perception and the activity of somatosensory neurons, but their effects are not fully understood at the level of individual neuron subtypes. Somatosensory neurons are a diverse population consisting of at least 18 identified subtypes, each of which may respond differently to estrogen and testosterone. Previous studies have often examined these neurons as a broad population, making it difficult to determine whether sex hormones activate specific pain-sensing neuron types or produce the same response across all neurons. Understanding these differences is important because variation in neuronal responses may contribute to sex-associated differences in pain sensitivity and the development of chronic pain.

This project aims to determine how estrogen and testosterone affect neural activity in primary trigeminal ganglion cultures and whether these responses differ among somatosensory neuron subtypes. Cultures are prepared from female mice so that the biological sex of the donor tissue remains consistent, allowing changes in neural activity to be more directly associated with hormone treatment rather than differences between male and female tissue. Cultured neurons are exposed to estrogen, testosterone, or control conditions and initially evaluated using immunofluorescence. Neural activity is assessed through c-Fos, an immediate-early gene product whose increased expression can serve as an indirect marker of neuronal activation.

The initial immunofluorescence experiments will establish whether the culture, hormone treatment, and staining system work reliably. Future experiments will use imaging mass cytometry, a multiplexed imaging method that can measure multiple cellular markers simultaneously. This approach will allow individual neurons to be classified by subtype while also measuring their activity and signaling responses to hormone exposure.

By identifying which sensory-neuron subtypes respond to estrogen and testosterone, this research may improve understanding of how sex hormones influence pain signaling. These findings could provide a foundation for future studies investigating sex-specific pain mechanisms and help the scientific community develop more targeted approaches for studying chronic pain.