Environmental contamination and the resulting food contamination represent a serious problem and pose a major threat to animal and human health. The gastrointestinal tract is directly exposed to a variety of substances. One is glyphosate, whose presence in the soil is commonly observed. This study demonstrates the effects of low and high glyphosate doses on the populations of intramural neurons of the porcine descending colon. An analysis was performed on neurons ex-pressing the vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide, a neuronal isoform of nitrogen oxide synthase, and galanin. Even a low dose of glyphosate increased the number of neurons immunoreactive against the studied substances. However, the changes depended on both the plexus analysed and the substance tested. Meanwhile, a high glyphosate dose resulted in quantitative changes (an increase in the number) within neurons immunoreactive against all the studied neuropeptides/enzymes in the myenteric plexus and both submucosal plexuses. The response of the enteric nervous system in the form of an increase in the number of neurons immunoreactive against neuroprotective substances may suggest that glyphosate has a toxic effect on enteric neurons which attempt to increase their survivability through the released neuroprotective substances.
Keywords: descending colon; enteric neurons; glyphosate; immunofluorescence; pig.