Ah Receptor-Mediated Impairment of Interrenal Steroidogenesis Involves StAR Protein and P450scc Gene Attenuation in Rainbow Trout
| Autor: | Mathilakath M. Vijayan, Neelakanteswar Aluru, R.L. Renaud, John F. Leatherland |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
endocrine system
medicine.medical_specialty Hydrocortisone Gene Expression Kidney Toxicology Receptors Glucocorticoid Glucocorticoid receptor beta-Naphthoflavone Internal medicine medicine Animals Cholesterol Side-Chain Cleavage Enzyme RNA Messenger Enzyme Inhibitors Receptor Benzoflavones biology Cholesterol side-chain cleavage enzyme Steroidogenic acute regulatory protein Brain Cytochrome P450 Kidney metabolism Phosphoproteins Aryl hydrocarbon receptor Diet Endocrinology Liver Receptors Aryl Hydrocarbon Oncorhynchus mykiss biology.protein Pregnenolone Drug Therapy Combination hormones hormone substitutes and hormone antagonists medicine.drug |
| Zdroj: | Toxicological Sciences. 84:260-269 |
| ISSN: | 1096-0929 1096-6080 |
| DOI: | 10.1093/toxsci/kfi077 |
| Popis: | The objective of the study was to investigate the impact of aryl hydrocarbon receptor (AhR) activation on interrenal steroidogenesis in rainbow trout. To this end, fish were fed AhR agonist (beta-naphthoflavone (BNF): 10 mg/kg body mass/day) and antagonist (alpha-naphthoflavone (ANF): 10 mg/kg body mass/day) either singly or in combination (ABNF) for 5 days to elucidate the mechanisms involved in AhR-mediated depression of cortisol production. Liver AhR protein expression was significantly elevated only with ABNF, but not with BNF and ANF compared to the control group. However, all three treatments (BNF, ANF, and ABNF) significantly elevated cytochrome P450 1A1 (CYP1A1) gene and protein expression in the kidney and liver, respectively. Also, these three treatment groups had significantly depressed ACTH-stimulated cortisol production in vitro compared to the control group. This attenuation of interrenal steroidogenesis corresponded with a lower mRNA abundance of steroidogenic acute regulatory (StAR) protein and cytochrome P450 cholesterol side chain cleavage enzyme (P450scc), but not 11beta-hydroxylase. Furthermore, in vitro incubation of head kidney pieces with 7-3H-pregnenolone failed to show any treatment effects on pathways downstream of P450scc, except for a significantly higher conversion to progesterone in the BNF and ANF groups. Plasma cortisol and glucose levels showed no significant change between the treated groups and control, but liver and brain glucocorticoid receptor (GR) protein expression was higher in the BNF group, and ANF abolished this response. Taken together, both BNF and ANF impaired cortisol production, and the mechanism may involve attenuation of StAR and P450scc, the rate limiting steps in steroidogenesis. Overall, endocrine disruption by xenobiotics acting via AhR includes impaired cortisol biosynthesis and abnormal cortisol target tissue GR responses in rainbow trout. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|