Agomelatine restores apoptotic and glial homeostasis in methotrexate-induced cortical neurotoxicity

Methotrexate (MTX), a commonly used chemotherapeutic and immunosuppressive agent, induces dose-dependent neurotoxicity characterized by oxidative stress, glial reactivity, and dysregulation of apoptotic signaling, contributing to chemotherapy-related cognitive impairment. Agomelatine (AGO), a melatonergic melatonin receptor type 1/melatonin receptor type 2 receptor agonist and 5-hydroxytryptamine receptor 2C antagonist, exhibits antioxidant, anti-inflammatory, and antiapoptotic properties, suggesting potential neuroprotection. Twenty-four female Wistar rats were randomly divided into control, MTX, MTX + AGO, and AGO groups (n = 6 each). AGO (20 mg/kg/d, by mouth) was administered for 7 days, with a single MTX injection (20 mg/kg, i.p.) on day 2. Cortical tissues were examined histopathologically (Hematoxylin and Eosin), immunohistochemically (glial fibrillary acidic protein and oligodendrocyte transcription factor 2), and molecularly via RT-quantitative polymerase chain reaction (qPCR) (Bcl-2-associated X protein and B-cell lymphoma 2 [BCL2]). MTX-induced marked cortical neurodegeneration, vascular hyperemia, gliosis, and parenchymal hemorrhage, accompanied by elevated glial fibrillary acidic protein and oligodendrocyte transcription factor 2 expression. MTX also increased proapoptotic Bcl-2-associated X protein and decreased antiapoptotic BCL2 expression, shifting the Bcl-2-associated X protein/BCL2 ratio toward apoptosis. AGO cotreatment significantly mitigated these alterations, preserving cortical cytoarchitecture, reducing glial activation, and restoring apoptotic balance. AGO alone upregulated BCL2 expression without histopathological abnormalities. AGO confers significant neuroprotection against MTX-induced cortical toxicity by attenuating glial reactivity and re-establishing apoptosis survival equilibrium. These findings highlight AGO as a promising adjunct therapeutic strategy for reducing chemotherapy-related neurotoxicity and improving neurological outcomes in MTX-treated patients. SIGNIFICANCE STATEMENT: Agomelatine, a clinically available melatonergic antidepressant, mitigated methotrexate-induced cortical neurotoxicity in rats by dampening astrocytic/oligodendrocytic reactivity and restoring the Bcl-2-associated X protein/B-cell lymphoma 2 apoptotic balance. These findings identify glial apoptotic homeostasis as a tractable target and support repurposing agomelatine as an adjunct to reduce chemotherapy-related neurotoxicity and potentially improve cognitive outcomes in methotrexate-treated patients.