Sexual Dimorphism of μ-Opioid Receptor Expression in Mouse A2 Neurons (2024)

Undergraduates: Jacob Beam, Andrew Fitzgerald, Nolan Frankel, Sadie Thomas

Faculty Advisor: Sabrina Robertson
Department: Neuroscience

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Norepinephrine-producing neurons are present throughout the brain stem and are involved in many different physiological and behavioral responses, most notably the ‘fight or flight’ response. Mu-opioid receptor (MOR) is present throughout the brain, but its prevalence in noradrenergic neurons, specifically in the A2 region of the mouse brain, is unknown. Immunohistochemistry was used to elucidate the expression of both noradrenergic neurons and MOR-expressing neurons in the mouse A2 region. Specifically, the prevalence of MOR was compared across male and female mice in order to determine if any sex differences exist between this endogenous opioid receptor in the noradrenergic system. Statistical analysis showed enhanced expression of MOR in the A2 region for both sexes when compared to negative control groups. Furthermore, it also showed increased expression of MOR in male mice when compared to female mice in the same brain region. These findings show that there are innate differences in receptor expression across male and female mice, and have great implications for further research and specialized treatment options for opiate abuse and other types of addiction.