Changes in c-Fos protein expression in telencephalic hemispheres of a neotropical fish Piaractus orinoquensis 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 (Piaractus orinoquensis) are frequently found in areas subjected to glyphosate aerial fumigation. This study aims to investigate changes in c-Fos protein expression in P. orinoquensis telencephalic hemispheres after exposure to 0, 1, 5, and 10 mg/L glyphosate for 30, 60, and 90 min. For this purpose, 5 µm 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 P. orinoquensis 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-Fos-expressing 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.