A molecular and phenotypic integrative approach to identify a no effect dose level for anti-androgen induced testicular toxicity

With the advent of high information content technologies, especially microarrays, it is pertinent to determine the impact of molecular data on the NOAELs. Consequently, we conducted an integrative study to identify a no transcriptomic effect dose using microarray analyses coupled with qPCR and determined how this correlated with the NOAEL. We assessed the testicular effects of the antiandrogen, flutamide (FM), in a rat 28-day toxicity study using doses of 0.2-30 mg/kg/day. Concerning molecular data, we observed differential gene expression starting from 1 mg/kg/day and a deregulation of more than 1500 genes at 30 mg/kg/day. Dose-related changes were identified for the major pathways associated with the testicular lesion (eg fatty acid metabolism), that were confirmed by qPCR. These data, along with standard measurements supported the no effect dose of 0.2 mg/kg/day. Flutamide was administered in suspension to rats (7 weeks old at start of treatment, 10 per group) by oral gavage at a daily dose of 0 (control), 0.2, 1, 6 and 30 mg/kg body weight, for 28 consecutive days. Dose-related changes in gene expression were determined in the testes using whole genome oligonucleotide microarrays.