Maintenance of cytochrome P450 content and phase I and phase II enzyme activities in trout hepatocytes cultured as spheroidal aggregates

Two complementary bioassays for screening the estrogenic potency of xenobiotics: recombinant yeast for trout estrogen receptor and trout hepatocyte cultures

“…The use of the yeast system to test fungicides may be questionable as most of the compounds appeared toxic. Nevertheless, some fungicides such as biphenyl and related metabolites previously shown to be active in mammals (Cravédi et al 1996 and JP Cravédi, A Lafuente, M Baradat, A Hillenweck & E Perdu-Durand, unpublished observations) exhibited estrogenic activity in both yeast and hepatocytes. Biphenyl activated gene transcription in both systems but was unable to displace [ 3 H]E 2 binding to the rtER.…”

“…We felt, however, that it was necessary to test, in a more elaborate biological system, compounds which were potent estrogens in yeast. For that purpose, we used rainbow trout hepatocytes, one of the main estrogen (E 2 )-target cells in fish, which possess most of the xenobiotic biotransformation capacity contained in the liver (Cravédi et al 1996). In the trout hepatocyte primary culture system, the regulation of the expression of several genes, particularly those of vitellogenin and estrogen receptor, has been extensively studied and was found to be remarkably similar to that which was observed in vivo (Flouriot et al , 1995.…”

Transcriptional regulation of expression of the rainbow trout albumin gene by estrogen

“…However, after 5-6 days, stabilization occurs, and Alb mRNA level remains stable for at least 1 month. We have previously shown that the expression of other liver-specific genes is also stably maintained during this last period (Flouriot et al 1993, Cravedi et al 1996. It should be noted that a decrease in Alb gene expression after liver dissociation and hepatocyte culture has also been reported for Xenopus and rat , Fraslin et al 1985, Jackson & Shapiro 1986, and the reasons for this difference in Alb gene expression in vivo and in vitro are not yet known.…”

“…For this reason, this organ is often used as a model to study regulation of expression of estrogen-dependent genes. Recently we developed an aggregate primary culture in which rainbow trout hepatocytes were able to maintain stable and specific gene expression over a period of 1 month (Flouriot et al 1993, Cravedi et al 1996. This culture system allowed us to study mechanisms involved in the E2 regulation of two estrogen-dependent genes: vitellogenin, which codes for the precursor of egg yolk proteins, and estrogen receptor (ER), the product of which is a ligandinducible transcription factor.…”

Genomic approach in evaluating the role of androgens on the growth of Atlantic cod (Gadus morhua) previtellogenic oocytes

“…However, a previous in vitro study by Mori et al (2000) demonstrated an almost ignorable conversion of T to E2 in primary cultures of immature male rainbow trout hepatocytes. In addition, HPLC studies showed that T is metabolized mainly into testosterone-glucuronide and androstenedione in these cells (Cravedi et al, 1996). While our study demonstrates that 11-KT and T gave rise to different expression patterns of transcripts directly involved in steroidogenesis, additional studies are needed to determine the precise role of aromatizable and non-aromatizable androgens in the regulation of ovarian steroidogenic genes and proteins in teleosts.…”