AUTHOR=Giardino William J., Cote Dawn M., Li Ju , Ryabinin Andrey E.

TITLE=Characterization of Genetic Differences within the Centrally Projecting Edinger–Westphal Nucleus of C57BL/6J and DBA/2J Mice by Expression Profiling

JOURNAL=Frontiers in Neuroanatomy

VOLUME=6

YEAR=2012

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2012.00005

DOI=10.3389/fnana.2012.00005

ISSN=1662-5129

ABSTRACT=<p>Detailed examination of the midbrain Edinger–Westphal (EW) nucleus revealed the existence of two distinct nuclei. One population of EW preganglionic (EWpg) neurons was found to control oculomotor functions, and a separate population of EW centrally projecting (EWcp) neurons was found to contain stress- and feeding-related neuropeptides. Although it has been shown that EWcp neurons are highly responsive to drugs of abuse and behavioral stress, a genetic characterization of the EWcp was needed. To identify genetic differences in the EWcp of inbred mouse strains that differ in behaviors relevant to EWcp function, we used publicly available tools from the Allen Brain Atlas to identify 68 transcripts that were selectively expressed in the EWcp, and examined their expression within tissue punch microdissection samples containing the EWcp of adult male C57BL/6J (B6) and DBA/2J (D2) mice. Using 96-well quantitative real-time PCR (qPCR) arrays that included the EWcp-specific genes, several other genes of interest, and five housekeeping genes, we identified strain differences in expression of 11 EWcp-specific genes (<italic>BC023892</italic>, <italic>Btg3</italic>, <italic>Bves</italic>, <italic>Cart</italic>, <italic>Cck</italic>, <italic>Ghsr</italic>, <italic>Neto1</italic>, <italic>Postn</italic>, <italic>Ptprn</italic>, <italic>Rcn1</italic>, and <italic>Ucn</italic>), two immediate early genes (<italic>Egr1</italic> and <italic>Fos</italic>), and one dopamine-related gene (<italic>Drd5</italic>). All significant expression differences were greater in B6 vs. D2 mice, and several of these were verified either at the protein level using immunohistochemistry (IHC) or <italic>in silico</italic> using microarray data sets from whole brain and other brain areas. These results demonstrate a significant advance in our understanding of the EWcp on three levels. First, we generated a list of EWcp-specific genes (most of which had not yet been reported within the EWcp in the literature) that will be informative for future studies of EWcp function. Second, due to similarity in results from qPCR and IHC, we revealed that strain differences in basal EWcp neuropeptide content are accounted for by differential transcription and number of peptidergic neurons, rather than by differential rates of peptide release. And third, our identification of differentially expressed EWcp-specific genes between B6 and D2 mice may hold powerful insight into the neurogenetic contributions of the EWcp to stress- and addiction-related behaviors.</p>