ToxSci Advance Access published online on June 18, 2009
Toxicological Sciences, doi:10.1093/toxsci/kfp135
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Atrazine Oral Exposure of Peripubertal Male Rats Down-Regulates Steroidogenesis Gene Expression in Leydig Cells
Laboratory for Ecotoxicology, Department of Biology and Ecology, University of Novi Sad Faculty of Sciences, 21000 Novi Sad, Serbia
Radmila Kovacevic, PhD, LECOTOX, Department of Biology and Ecology, University of Novi Sad, Faculty of Sciences, Trg D. Obradovica 2, 21000 Novi Sad, Serbia, Tel: +381 21 485 2675, Fax: +381 21 450 620, E-mail: radmilak{at}ib.ns.ac.yu
Received April 2, 2009; revision received June 3, 2009; accepted June 15, 2009
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Abstract |
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In the present study, we investigated the effects of oral dosing of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) to peripubertal male rats (50mg/kg and 200mg/kg body weight daily from postnatal day 23 to 50) on ex vivo Leydig cell steroidogenesis. Leydig cells from treated rats were characterised by significant decline in mRNA transcripts of several genes responsible for steroidogenesis: luteinizing hormone receptor (LHR), scavenger receptor-B1, steroidogenic acute regulatory protein, translocator protein, steroidogenic factor-1, phosphodiesterase 4B, 3β–hydroxysteroid dehydrogenase (HSD), CYP17A1 and 17βHSD. In the presence of human chorion gonadotropin, the dose-dependent decrease in extra cellular cAMP level and accordingly strong inhibition of androgenesis were obtained. The transcription of LHR gene in Leydig cells of atrazine-treated rats was down-regulated in a dose-dependent manner, which could be the reason for reduction in cAMP level and expression of cAMP-dependent genes. To clarify the activity of the steroidogenic enzymes responsible for androgenesis, purified Leydig cells were challenged with different steroid substrates (22OH-cholesterol, pregnenolone, progesterone and 
4–androstenedione), and the obtained results indicated inhibition of androgen production in Leydig cells isolated from atrazine-treated animals in the presence of all those substrates. However, when Leydig cells were challenged with 22OH-cholesterol, the progesterone level in the incubation medium was unchanged, indicating that decrease in cholesterol transport and/or CYP17A1 and 17βHSD activity are most probably responsible for inhibition of androgen production after the addition of different substrates. Our results demonstrated that in vivo exposure to atrazine affects Leydig cell steroidogenesis via the inhibition of steroidogenesis gene expression, which is accompanied by decreased androgenesis.
Key Words: atrazine; gene expression; LC steroidogenesis.