ORIGINAL ABSTRACT

Glyphosate (GLY) is a widely used herbicide, particularly in agriculture, and its residues in plants and soil can induce toxic effects in various organisms, including humans, with the brain being especially vulnerable. Eugenol (EU), a natural antioxidant found in cloves, has demonstrated protective effects against different toxic substances. This experimental study explored whether eugenol could mitigate neurological damage triggered by glyphosate exposure in rats. A total of forty male Sprague-Dawley rats were allocated into five experimental groups consisting of control, eugenol (100 mg/kg), glyphosate (150 mg/kg), EU50 combined with glyphosate (50 mg/kg + 150 mg/kg), and EU100 combined with glyphosate (100 mg/kg + 150 mg/kg). Animals received the respective treatments by oral gavage for a period of seven days. Motor and anxiety-related behaviors were evaluated using behaviour tests, after which brain tissues were processed for histopathological analysis. Biochemical analyses included ELISA assessment of oxidative stress markers (MDA, SOD1, GSH, and GPx1), RT-PCR analysis of endoplasmic reticulum (ER) stress- and apoptosis-related genes (GRP78, ATF4, CHOP, PI3K/AKT/mTOR, BAX, and Bcl-2), Western blot evaluation of inflammatory and antioxidant signaling pathways (TLR4/NF-κB and Nrf2/HO-1/SIRT1), and immunohistochemical and immunofluorescence analyses of neuroplasticity, circadian rhythm, and autophagy markers (BDNF, BMAL1, CLOCK, Beclin-1, and LC3A/B). GLY exposure significantly increased lipid peroxidation (MDA), ER stress markers (GRP78 and CHOP), pro-inflammatory mediators (TLR4, NF-κB, TNF-α, and IL-1β), apoptotic signaling (BAX and caspase-3), and autophagy-related proteins, while suppressing antioxidant pathway components. Glyphosate exposure induced behavioral impairments accompanied by increased oxidative stress, inflammatory activation, endoplasmic reticulum stress, apoptosis, and dysregulated autophagy in cerebral cortex tissue. EU treatment dose-dependently attenuated these molecular and histopathological alterations, restored antioxidant and cellular stress responses, and significantly improved behavioral performance, indicating a protective role against GLY-induced neurotoxicity. Overall, EU may represent a promising therapeutic candidate for mitigating herbicide-induced brain injury.