Chapter

Inducible Aromatase in Astroglia: Protection and Recovery from Neural Perturbation in Birds

Kelli A. Duncan and Colin J. Saldanha

in Brain Aromatase, Estrogens, and Behavior

Published in print October 2012 | ISBN: 9780199841196
Published online January 2013 | e-ISBN: 9780199979837 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780199841196.003.0020

Series: Oxford Series in Behavioral Neuroendocrinology

Inducible Aromatase in Astroglia: Protection and Recovery from Neural Perturbation in Birds

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In the avian brain, aromatase is constitutive and inducible in neurons and glia respectively. Glial aromatase is rapidly and dramatically upregulated in astroglia (astrocytes and radial glia) independent of brain region, in response to perturbation of the neuropil. Estrogens, synthesized by induced aromatization in glial cells, are potent mitigators of apoptotic degeneration and may accelerate neuronal replacement following brain damage. Specifically, aromatase inhibition increases, and estradiol replacement decreases secondary degeneration at the site of primary damage in the passerine brain. Indeed, the characteristic wave of secondary degeneration observed in mammals following compromise of the brain, is severely dampened in the passerine brain and is only revealed following inhibition of inducible glial aromatization. Further, the rate of injury-induced neurogenesis is increased in birds receiving estradiol replacement relative to those treated with an aromatase inhibitor alone. This chapter reviews data on the structural and functional consequences of glial aromatization. It highlights emerging data on the signals that invariably accompany brain damage and their potential role as inductive signals for the transcription and translation of the aromatase gene specifically in glial cells. The robust and cell-specific expression of aromatase in the passerine brain continues to provide an excellent model for the study of the provision of estrogens to neural targets with temporal and spatial specificity. In addition to basic scientific questions, passerine songbirds may serve as superb animal models toward understanding clinical syndromes involving brain damage, ischemia/anoxia, and neurodegeneration.

Keywords: anoxia; apoptosis; astroglia; cytokines; ischemia; microglia; mitosis; neurodegeneration; neuroinflammation; testosterone

Chapter.  5582 words.  Illustrated.

Subjects: Neuroscience

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