The effect of stress on steroidogenic gene transcription in the Atlantic stingray (Dasyatis sabina) brain

This study investigated the steroidogenic capacity of the Atlantic stingray (Dasyatis sabina) brain by examining the expression of steroidogenic genes in four sections of the brain (corpus cerebellum, telencephalon, tectum and medulla). Primer sequences specific for D. sabina steroidogenic factor-1 (SF-1), side chain cleavage (SCC), steroidogenic acute regulatory protein (StAR), 3[Greek letter Beta]-hydroxysteroid dehydrogenase (3[Greek letter Beta]-HSD) and 11[Greek letter Beta]-hydroxylase were used in RT-PCR to determine if their corresponding mRNAs are present in D. sabina medulla, corpus cerebellum, tectum and telencephalon, from unstressed and stressed adult stingrays (disc width [less than or equal to] 30 cm). Between both sexes and stress states, each of the genes investigated was present in at least one area of the brain, with usually more than one gene being present in a specific brain region. SCC, StAR and SF-1 were not as abundant as 11[Greek letter Beta]-hydroxylase, aromatase and 3[Greek letter Beta]-HSD, suggesting that rather than being capable of de novo synthesis, the D. sabina brain might be more involved in the activation of circulating steroids. Digital, semi-quantitative analysis of gene expression did not show statistically significant changes in gene expression with stress, or between the brain regions or sex. However, an interesting trend is seen in the males: males tended to produce less aromatase and more 11[Greek letter Beta]-hydroxylase when stressed, suggesting a switch from the production of estrogens to androgens under stress. This study suggests that the D. sabina brain is capable of steroidogenesis, and that stress may play an important role in regulating steroidogenic gene expression, though further work is needed to determine the types of neurosteroids produced.