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J Neuroendocrinol February 26, 2014;

Cyp19a1 (aromatase) expression in the Xenopus brain at different developmental stages.

Coumailleau P , Kah O .

Cytochrome P450 aromatase (P450arom; aromatase) is a microsomal enzyme involved in the production of endogeneous sex steroids by converting testosterone (T) into oestradiol (E2). Aromatase is the product of the cyp19a1 gene and plays a crucial role in the sexual differentiation of the brain and in the regulation of reproductive functions. In the brain of mammals and birds, expression of cyp19a1 has been evidenced essentially in neuronal populations of the telencephalon and diencephalon. In contrast, a wealth of evidence established that in teleost fishes, aromatase expression in the brain is restricted to radial glial cells. The current study investigated the precise neuroanatomical distribution of cyp19a1 mRNA during brain development in Xenopus laevis (late embryonic to juvenile stages). For this purpose, we used in situ hybridization alone or combined with the detection of a proliferative (PCNA), glial (BLBP, Vimentin) or neuronal (Acetyl-tub; HuC/D; NeuroβTubulin) markers. We provide evidence that cyp19a1 expression in the brain is initiated from very early larval stage and remains strongly detected until juvenile and adult stages. At all stages analysed, we found the highest expression of cyp19a1 in the preoptic area and the hypothalamus as compared to the rest of the brain. In these two brain regions, cyp19a1-positive cells were never detected in the ventricular layers. Indeed, no co-labelling could be observed with radial glial (BLBP, Vimentin) or dividing progenitors (PCNA) markers. On the contrary, cyp19a1-positive cells perfectly matched with the distribution of post-mitotic neurones as shown by the use of specific markers (HuC/D, Acetyl-tub and Neuroβtubulin). These data suggest that, similar to what was found in other tetrapods, aromatase in the brain of amphibians is found in post-mitotic neurones and not in radial glia as reported in teleosts. This article is protected by copyright. All rights reserved.

PubMed ID: 24612124
PMC ID: PMC4238815
Article link: J Neuroendocrinol

Species referenced: Xenopus laevis
Genes referenced: cyp19a1 cyp4b1 elavl3 fabp7 pcna tub vim vim.2

Article Images: [+] show captions
References [+] :
Abdelgadir, Distribution of aromatase cytochrome P450 messenger ribonucleic acid in adult rhesus monkey brains. 1997, Pubmed