Mu-opioid receptor and norepinephrine neuron colocalization in the A7 of male and female mice (2023)
Undergraduates: Sam Tabet, Cameron Griffin, Adi Kumar, Ananyaa Sundar
Faculty Advisor: Sabrina Robertson
Department: Psychology & Neuroscience
Women suffer from higher incidences of stress-related mental disorders (5,15). The CNS modulates stress and pain through norepinephrine (NE) release, and discrepancies in the NE system between sexes may account for the observed difference in the prevalence of certain psychopathologies. Extensive research has analyzed sexual dimorphism within the primary NE nucleus, the locus coeruleus (LC), revealing increased regulation of the male LC by mu-opioid receptor (MOR) and increased regulation of the female LC by corticotropin-releasing factor (CRF) (8,13). However, there has been little examination of potential sex differences in the A7 nucleus, a NE center that is vital in the integration of nociceptive signaling (12). Similar to the LC, the A7 can also be regulated by MORs (14). Hence, the present study aimed to quantify MOR colocalization with NE neurons in the A7 between male and female mice. Transgenic mice expressing eGFP in NE neurons were labeled using a dual antibody immunohistochemistry approach. Quantification of fluorescence signals revealed no statistically significant difference in MOR NE neuron colocalization in the A7 between male and female mice. While data tended towards greater colocalization in male subjects, the generalizability of these results is limited by the small sample size and the lack of statistical significance. The A7 region could still harbor sexually dimorphic characteristics, and we recommend continued examination of A7 mechanistic control of nociceptive intensity in both males and females.
Link to Poster