Estrogenic and anti-estrogenic influences in cultured brown trout hepatocytes: Focus on the expression of some estrogen and peroxisomal related genes and linked phenotypic anchors

- Evidence of crosstalk between estrogens and peroxisomal pathways in brown trout.
- VtgA and ERα mRNA levels increased after 1, 10 and 50 μM of ethinylestradiol (EE2).
- ERβ-1, catalase and urate oxidase mRNA levels decreased after estrogenic stimuli.
- Estrogenic effects in VtgA, ERα and Uox mRNA levels were reverted by ICI 182,780.
- Immunofluorescence/electron microscopy shows smaller peroxisomes after 50 μM of EE2.

Estrogens, estrogenic mimics and anti-estrogenic compounds are known to target estrogen receptors (ER) that can modulate other nuclear receptor signaling pathways, such as those controlled by the peroxisome proliferator-activated receptor (PPAR), and alter organelle (inc. peroxisome) morphodynamics. By using primary isolated brown trout (Salmo trutta f. fario) hepatocytes after 72 and 96 h of exposure we evaluated some effects in selected molecular targets and in peroxisomal morphological features caused by: (1) an ER agonist (ethinylestradiol-EE2) at 1, 10 and 50 μM; (2) an ER antagonist (ICI 182,780) at 10 and 50 μM; and (3) mixtures of both (Mix I-10 μM EE2 and 50 μM ICI; Mix II-1 μM EE2 and 10 μM ICI and Mix III-1 μM EE2 and 50 μM ICI). The mRNA levels of the estrogenic targets (ERα, ERβ-1 and vitellogenin A-VtgA) and the peroxisome structure/function related genes (catalase, urate oxidase-Uox, 17β-hydroxysteroid dehydrogenase 4-17β-HSD4, peroxin 11α-Pex11α and PPARα) were analyzed by real-time polymerase chain reaction (RT-PCR).Stereology combined with catalase immunofluorescence revealed a significant reduction in peroxisome volume densities at 50 μM of EE2 exposure. Concomitantly, at the same concentration, electron microscopy showed smaller peroxisome profiles, exacerbated proliferation of rough endoplasmic reticulum, and a generalized cytoplasmic vacuolization of hepatocytes. Catalase and Uox mRNA levels decreased in all estrogenic stimuli conditions. VtgA and ERα mRNA increased after all EE2 treatments, while ERβ-1 had an inverse pattern. The EE2 action was reversed by ICI 182,780 in a concentration-dependent manner, for VtgA, ERα and Uox. Overall, our data show the great value of primary brown trout hepatocytes to study the effects of estrogenic/anti-estrogenic inputs in peroxisome kinetics and in ER and PPARα signaling, backing the still open hypothesis of crosstalk interactions between these pathways and calling for more mechanistic experiments.