Sex- and population-specific hormetic responses to increasing dietary selenium in zebrafish (Danio rerio)

We tested the hypothesis that the behavioral response to selenium (Se) follows a hormetic dose response pattern, manifested through the functions of selenoproteins within the brain. We measured anxiety-related behaviors in zebrafish (Danio rerio) at deficient, control and supplemented levels of dietary Se, and measured the transcriptional response of selenoprotein genes important for neuroprotection. We also used a microarray approach to assess the transcriptomic response of the midbrain to Se. The behavioral response to Se was characterized by hormesis, and the direction, magnitude, and shape of the hormetic responses were dependent on both sex and zebrafish population. Transcription of selenoproteins within the midbrain also responded to Se in a similar hormetic dose-dependent manner, with sex and population influencing the trajectory of the responses. The hormetic behavioral response to Se may therefore be manifested through selenoproteins in the brain, but the influence is not direct. We performed a microarray analysis comparing the midbrain-specific transcriptome between male zebrafish from two populations (Pargana: P and Transgenic Mosaic 1: T) fed either a control, Se deficient, or Se supplemented diet (17 total samples: 9 fish per population, 3 fish per diet: missing 1 P control sample).