Clustered organization and region‐specific identities of estrogen‐producing neurons in the forebrain of Zebra Finches (Taeniopygia guttata). Issue 17 (15th August 2017)

• Record Type: Journal Article
• Authors: Ikeda, Maaya Z.; Krentzel, Amanda A.; Oliver, Tessa J.; Scarpa, Garrett B.; Remage‐Healey, Luke
• Is Part Of: Journal of comparative neurology. Volume 525:Issue 17(2017)
• Page Start: 3636
• Page End: 3652
• Publication Date: 2017-08-15
• Subjects: aromatase -- auditory -- calbindin -- estradiol -- microcircuit -- parvalbumin -- pallium -- RRID: AB_476894 -- RRID: AB_2174013 -- RRID: AB_2092365 -- RRID: AB_2298772; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.24292
• Languages: English
• ISSNs: 0021-9967

Abstract

Abstract: A fast, neuromodulatory role for estrogen signaling has been reported in many regions of the vertebrate brain. Regional differences in the cellular distribution of aromatase (estrogen synthase) in several species suggest that mechanisms for neuroestrogen signaling differ between and even within brain regions. A more comprehensive understanding of neuroestrogen signaling depends on characterizing the cellular identities of neurons that express aromatase. Calcium‐binding proteins such as parvalbumin and calbindin are molecular markers for interneuron subtypes, and are co‐expressed with aromatase in human temporal cortex. Songbirds like the zebra finch have become important models to understand the brain synthesis of steroids like estrogens and the implications for neurobiology and behavior. Here, we investigated the regional differences in cytoarchitecture and cellular identities of aromatase‐expressing neurons in the auditory and sensorimotor forebrain of zebra finches. Aromatase was co‐expressed with parvalbumin in the caudomedial nidopallium (NCM) and HVC shelf (proper name) but not in the caudolateral nidopallium (NCL) or hippocampus. By contrast, calbindin was not co‐expressed with aromatase in any region investigated. Notably, aromatase‐expressing neurons were found in dense somato‐somatic clusters, suggesting a coordinated release of local neuroestrogens from clustered neurons. Aromatase clusters were also more abundant and tightly packed in the NCM of males as compared to females. Overall, this study provides new insights into neuroestrogen regulation at the network level, and extends previous findings from human cortex by identifying a subset of aromatase neurons as putative inhibitory interneurons. Abstract : Zebra finch auditory forebrain regions are capable of rapid, local synthesis of estrogens. We describe the density and identity of aromatase neurons, and we find coexpression with the interneuron marker parvalbumin. Aromatase neurons are found in clusters (circled) with each other and with other neuron subtypes in patterns that are sexually dimorphic.