Neurotoxicological effects of the herbicide glyphosate

Abstract

Glyphosate is a nonselective herbicide that inhibits plant growth through interference with the production of essential aromatic amino acids. Glyphosate have been extensively investigated for the potential to produce adverse health effects in humans. Studies point out that glyphosate may be a factor in the birth defects (autism, attention-deficit, and hyperactivity disorder) observed among children of herbicide applicators. Government regulatory agencies are reviewing the available scientific data to reevaluate the safety of glyphosate. The purpose of this work is to describe neurotoxicological effects following the administration of glyphosate (75, 150 and 800 mg/kg/day, orally for 5 days) in male Wistar rats (n = 6/group). Animals were sacrificed 24 h following the last dose of glyphosate and the brains were removed. The frontal cortex, midbrain and striatum were dissected and analyzed for the content of the neurotransmitters 5-hydroxytryptamine (5-HT) and itsmetabolite 5-hydroxy-3-indole acetic acid (5-HIAA), and dopamine (DA) and itsmetabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), using a HPLC method with electrochemical detection. A serotonin and dopamine depleting, dose-dependent, effectswere produced by glyphosate. Glyphosate, at the highest dose, decreased 5-HT levels in frontal cortex (32%, P < 0.001), midbrain (22%, P < 0.001) and striatum (49%, P < 0.001). Similarly, glyphosate, at the highest dose, decreased DA levels in frontal cortex (53%, P < 0.01), midbrain (15%, P < 0.001) and striatum (22%, P < 0.001) respect to controls. Also, glyphosate caused a statistically significant increase in the metabolites of serotonin and dopamine.