Changes in c-Fos protein expression in telencephalic hemispheres of a neotropical fish <i>Piaractus orinoquensis</i> after exposure to a glyphosate-based herbicide.

Glyphosate-based herbicides (GBHs) can be found in waterbodies and may affect aquatic populations, resulting in physiological and behavioral impairments. In Colombia, white cachama (<i>Piaractus orinoquensis</i>) are frequently found in areas subjected to glyphosate aerial fumigation. This study aims to investigate changes in c-Fos protein expression in <i>P. orinoquensis</i> telencephalic hemispheres after exposure to 0, 1, 5, and 10 mg/L glyphosate for 30, 60, and 90 min. For this purpose, 5 lm paraffin sections were obtained and used for c-Fos immunodetection. To define the effect of xenobiotics on c-Fos expression, nuclei were taken from the dorsal dorsal (Dd), dorsomedial (Dm), dorsal posterior (Dp), dorsolateral (Dl), ventral (Vv), dorsoventral (Vd), and ventrolateral (Vl) regions of <i>P. orinoquensis</i> telencephalic hemispheres. Except for Dd nuclei, other nuclei showed an initial increase in c-Fos+ cells, followed by a progressive decrease toward values similar to those observed in unexposed individuals. In Dd nuclei, the initial tendency was toward a reduced number of c-Fosexpressing cells, followed by an increase in unexposed values. As changes in the number of cells containing c-Fos can be related to changes in neuronal activity, GBH exposure may potentially affect the fish's behavioral and sensorial performance, resulting in a reduced survival probability in its natural environment.