Global warming and glyphosate toxicity (I): Adult zebrafish modelling with behavioural, immunohistochemical and metabolomic approaches.

Global warming further increases the toxic threat of environmental pollutants on organisms. In order to reveal the dimensions of this threat more clearly, it is of great importance that the studies be carried out with temperature differences as close as possible to the temperature values that will represent the global climate projection. In our study, how the toxicity of glyphosate, which is widely used around the world, on zebrafish changes with temperature increases of 0.5° was investigated on behavioral and molecular basis. For this purpose, adult zebrafish were exposed to glyphosate at concentrations of 1 ppm and 5 ppm for 96 h in four environments with a temperature difference of 0.5° (28.5; 29.0; 29.5; 30.0 °C). At the end of the exposure, half of the zebrafish were sampled and remaining half were left for a 10-day recovery process. At the end of the trials, zebrafish were subjected to circadian rhythm and anxiety tests. In addition, histopathological, immunohistochemical and metabolome analyses were performed on brain tissues. As a result, it has been detected that anxiety and circadian rhythm were disrupted in parallel with the increased temperature and glyphosate concentration, and increased histopathological findings and 5-HT4R and GNAT2 immunopositivity in the brain. As a result of metabolome analysis, more than thirty annotated metabolites have been determined due to the synergistic effect of temperature increase and glyphosate exposure. As a conclusion, it was concluded that even a temperature increase of 0.5° caused an increasing effect of glyphosate toxicity in the zebrafish model.