Endocrine Abstracts

Neurosteroids are synthesized locally within the central nervous system and play essential roles in modulating neuronal activity and various brain functions. They can have a wide range of effects, including anxiolytic, sedative, analgesic, and neuroprotective actions. Understanding their distribution in the brain and how they interact with neurotransmitter systems is of significant interest to researchers studying brain function and related disorders. We aim to construct a 3D atlas of a panel of neurosteroids to uncover the complex network of functions of neurosteroids in the mouse brain. Mass spectrometry imaging (MSI) is a powerful bioimaging tool that combines mass spectrometry with spatial information to three-dimensional maps of the distribution of molecules within a sample with direct histopathological correlation. Matrix assisted laser desorption ionisation (MALDI)-MSI was used to create distribution maps of neurosteroids, with 100 and 150 µm spatial resolution, from brains of 56-days-old male and female C57BL/6 mice. Serial sagittal 10µm cryostat brain sections were collected at around 200 µm intervals across the right hemisphere from cortex to midline. On-tissue chemical derivatisation with Girard-T reagent was applied to enhance the signal sensitivity of detection of neurosteroids containing keto functional groups. MSI data were collected on Bruker-12T-SolariX-Fourier-transform–ion-cyclotron-resonance (FT-ICR)-MS. Estrone, androstenedione, 7aOH-DHEA, progesterone, 17aOH-Progesterone/11-deoxycorticosterone, 11-dehydrocorticosterone and corticosterone were detected in brains from both sexes, mainly localised in cortex, hippocampus and cerebellums. Z-Stacking of sequential MSI plates allow generation of 3D models. Future work includes MSI data alignment and co-registration with the 20 Allen Mouse Brain Reference Atlas. This will be made publicly available via interactive webpages to allow precise anatomical annotations to search and visualise concentrations of individual neurosteroids in different areas of the mouse brain.