Mass spectrometric imaging of molecular distributions in the brain

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DESCRIPTION (provided by applicant): The zebra finch, a songbird, is an important model for studying neurogenesis, neural circuit development, and learning and memory. The male zebra finch learns to sing during a critical period in juvenile development. This development is under the control of anatomically discreet "song nuclei". Molecular genetics and cell culture experiments have suggested that various lipids and neurosteroids play a key role in song circuit formation in males. The ability to study lipids has been has been limited by complex tissue preparations, chemical labeling, and analyte pre-selection. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), an emerging technology in the analysis of complex biological samples, has overcome these hurdles. The technology has been successful in detecting and imaging various lipids and other small molecules in a mouse brain section and in muscle tissue while our collaborators have imaged the distribution of vitamin E in isolated single neurons. Our published results have shown for the first time the localization of various fatty acids in two song nuclei that are essential for learning and memory in the zebra finch. Preliminary results suggest changes in the presence and relative concentration of lipids, in regions known to be important in song learning and memory, are dependent on the zebra finch age, juvenile (song learning) or adult (song crystallization). Future studies will consist of: 1) collecting mass spectral data by ToF-SIMS from different aged birds and employing statistical methods to look at relative changes in concentration of lipids and other small molecules; 2) test the hypothesis that estrogen aids in localizing small molecules to the song nuclei HVC-RA during masculinization; 3) detect and image the spatial localization of neurosteroids and their precursors in the zebra finch brain by ToF-SIMS to generate a "neruosteroid map". PUBLIC HEALTH RELEVANCE: The ability to detect and image the spatial localizationof lipids and other small molecules would significantly impact the study of such neurodegenerative diseases as Alzheimer's and Parkinson's. In addition, it would enhance our understanding of subcellular changes during the critical period of development in areas involved in learning and memory. Finally, the potential to detect and image steroids would open new doors in neurobiology and the larger fields of endocrinology and cell signaling.