PNNL

Abstract

Normal transcriptomic patterns along the brain-pituitary- gonad- liver (BPGL) axis should be better characterized if endocrine disrupting compound induced changes in gene expression are to be understood. Female rainbow trout were studied over a complete, year-long reproductive cycle. Tissue samples from pituitary, ovary, and liver were collected for microarray analysis using the 16K GRASP (Genomic Research on Atlantic Salmon Project) microarray and for qPCR measures of estrogen receptor (ER) isoform mRNA levels. Plasma was collected to determine levels of circulating estradiol-17ß (E2), follicle stimulating hormone (FSH) and luteinizing hormone (LH). As an a priori hypothesis, changes in gene expression were correlated to either circulating levels of E2, FSH, and LH, or ER mRNAs quantified by qPCR. In the liver, most transcriptomic patterns correlated either to levels of E2, LH, or ERs. Fewer ovarian transcripts could be correlated to levels of E2, ERa, or FSH. No significant associations were obvious in the pituitary. As a post hoc hypothesis, changes in transcript abundance were compared to microarray features with known roles in gonadal maturation Many altered transcripts in the ovary correlated to transcript levels of 17 B HSD8 or 17 B HSD12, or to glycoprotein alpha chain 1 or 2. In the pituitary, genes involved with the growth axis (e.g., Growth Hormone, Insulin related growth factor binding protein) correlated with the most transcripts. These results suggest that transcriptional networks along the BPGL axis may be regulated by factors other than circulating steroid hormones.