Glyphosate induces neurotoxicity in zebrafish

Area of Science:

• Developmental toxicology
• Neuroscience
• Environmental science

Background:

• Glyphosate-based herbicides (GBHs) are widely used globally.
• Concerns exist regarding their safety, with some studies suggesting teratogenic effects.

Purpose of the Study:

• To investigate the early developmental toxicity of glyphosate and Roundup Classic formulation in zebrafish.
• To assess morphological and molecular changes in response to glyphosate exposure.

Main Methods:

• Utilized zebrafish as a vertebrate model system.
• Exposed embryos to technical grade glyphosate and Roundup Classic.
• Analyzed morphological abnormalities via observation.
• Assessed gene expression using in situ hybridization for pax2, pax6, otx2, ephA4, krox-20, and hoxb1a.
• Evaluated Retinoic Acid (RA) signaling using a reporter transgenic.

Main Results:

• Observed morphological abnormalities including reduced head and eye size, and loss of brain ventricle delineation.
• Detected decreased expression of key genes (pax2, pax6, otx2, ephA4) in the eye, forebrain, and midbrain.
• Found no changes in hindbrain gene expression (ephA4, krox-20, hoxb1a).
• Observed a loss of Retinoic Acid signaling in the retina but not in the hindbrain or spinal cord.

Conclusions:

• Glyphosate and Roundup Classic formulation exhibit developmental toxicity to the zebrafish forebrain and midbrain.
• The hindbrain and spinal cord appear unaffected by 24-hour glyphosate exposure.
• Findings suggest potential neurodevelopmental risks associated with glyphosate-based herbicides.