Altered expression of aromatase mRNA in the brain of adult Xenopus laevis exposed to Lambro river water and (anti)estrogenic/(anti)androgenic model compounds

Description

The production of estrogens in the brain is a highly important function in vertebrate reproduction and brain development. Aromatase (CYP19) that catalyzes the conversion of androgens to estrogens which is a rate-limiting step estrogen biosynthesis. Adult Xenopus laevis were exposed in vivo to Lambro (LAM) river water, the most polluted tributary of the Po river in North Italy, chosen as a representative water course discharging industrialized areas. In parallel, adult X. laevis were exposed to the following known (anti)estrogenic and (anti)androgenic compounds tamoxifen (TAM), ethinylestradiol (EE2), flutamide (FLU) and methyldihydrotestosterone (MDHT), 10−8 M. Expression of CYP19 was evaluated in brain obtained from females and males from all experimental conditions by quantitative RT_PCR using specific primers located in the ORF that allowed the simultaneous amplification of all transcripts. Differences in expression between treatments were analyzed by ANOVA followed by Bonferroni post-test. In general, males had similar CYP19 mRNA level compared to females, as usually observed in vertebrates. The mRNA expression of CYP19 was significantly up-regulated in both EE2 and MDHT exposed males and down-regulated in both MDHT and TAM exposed females. A general up-regulation of CYP19 mRNA expression was observed in females and males exposed to LAM. Moreover, in order to investigate the role of the tissue specific brain and gonad aromatase, recently described for X. laevis, primers were prepared, based on cDNA sequences for Xenopus cyp19 brain specific 5'UTR and gonad specific 5'UTR (Genbank accession numbers: AB272088, AB272087).

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