Regulation of the GST Mu-1 isoenzyme in Y1 cells by adrenocorticotropic hormone is primarily transcriptional

Behavioral, metabolic, and biochemical alterations caused by an acute stress event in a zebrafish larvae model

Animal welfare is a growing concern in aquaculture practices. Stress induced by handling or transportation can lead to negative impacts on the sector. Zebrafish has raised as an important aquaculture model, but still with few focus on its stress response in early life stages. Therefore, the objective of this study was to improve the evaluation of different markers of the stress response after a stress event in a zebrafish larvae model. Zebrafish larvae (96 hpf) were vortex-stimulated for 1 min at 200 rpm for acute stress induction. After 10 min, 1- and 4-h behavioral larvae outcomes and larvae were sampled to the following quantification: levels of cortisol, lactate, glucose and biochemical biomarkers (reactive oxygen species, superoxide dismutase, catalase, glutathione peroxidase, lipidic oxidation level and protein carbonylation, glutathione s-transferase, acetylcholinesterase, lactate dehydrogenase and ATPase), and the metabolic rate. The cortisol, glucose, and lactate levels had no alterations. At the behavioral level, an increase in the distance swam and in the speed was observed and the metabolic rate also increased according to the behavioral outcomes. The ATPase and GST activity showed a decrease in their activity, probably through osmoregulation changes related to the hypothetic adrenocorticotropic hormone downregulation. Overall, the acute vortex stimulation at low speed induced an early stress response independent of the HPI-cortisol pathway. In addition, this study shows zebrafish early life stages as a sensitive model to acute vortex stimulation, identifying altered parameters which can be used in future work to assess the effect on animal welfare in similar acute situations.

Expression profiles of glutathione S-transferase genes in larval midgut of Bombyx mori exposed to insect hormones

Glutathione S-transferases (GSTs) are believed to play a role in the detoxification of xenobiotics, resistance to insect viruses and pesticides, intracellular transport, biosynthesis of hormones and protection against oxidative stress. In this study, we used quantitative real time RT-PCR to examine expression profiles of the silkworm Bombyx mori GST-Sigma (BmGSTS2) and GST-Delta (BmGSTD2) genes in the larval midgut of the silkworm after exposure to 2-hydroxyecdysone (20E) and juvenile hormone analog (JHA). In concentration-course study, 20E at higher concentrations (1.0 and 2.0 μg/μl) caused significant upregulation of BmGSTD2, and all concentrations (0.5-2.0 μg/μl) of 20E caused significant upregulation of BmGSTS2. However, JHA in all concentrations downregulated the expression of BmGSTD2 and BmGSTS2. When exposed to either 20E (2.0 μg/μl) or JHA (2.0 μg/μl) on the third day of the fifth instar, the silkworm had higher BmGSTD2 at later time points: 15, 18, and 24 h for 20E and 24 h for JHA. BmGSTS2 expression was downregulated within 24 h after exposure to JHA and showed a time-dependent response after exposure to 20E. We also did a stage-dependent study, in which JHA downregulated BmGSTD2 expression and upregulated BmGSTS2 expression significantly at both day 1 and day 3 of the fifth instar. 20E upregulated the expression of BmGSTD2 and BmGSTS2 at the two stages. These findings imply that hormones have an important role in the regulation of basal GST expression. However, further validation and field trials should be carried out on the regulatory elements relevant to BmGSTD2 and BmGSTS2 gene expression.