Developmental Exposure to Atrazine Impairs Spatial Memory and Downregulates the Hippocampal D1 Dopamine Receptor and cAMP-Dependent Signaling Pathway in Rats

Atrazine (ATR) is a widely used herbicide that has been implicated as a neurotoxicant. Recent experimental evidence has implicated that ATR exposure also appears to have adverse effects on the hippocampus, which is a critical region for learning and memory. The aim of the present study was to investigate the effects of ATR toxicity on the hippocampus of developing rats. Postnatal day (PND) 28 male Sprague–Dawley (SD) rats received ATR by oral gavage at 10 or 100 mg/kg bodyweight (BW) for 30 consecutive days and were sacrificed at PND 90. Behavioral test results indicated that spatial learning and memory were affected by ATR treatment. Electron microscopy analysis showed that the ultrastructures of the hippocampus were altered in the ATR-treated groups, as compared to the control group. Additionally, ATR treatment impacted dopamine and D1 dopamine receptor (D1DR) contents through different mechanisms. Reduced mRNA and protein expression levels of factors involved in the cAMP-dependent signaling pathway were also detected. These results indicate that the developmental exposure of rats to ATR can damage the hippocampus and spatial memory, which might be related to the downregulation of expression levels of the D1DR and its downstream signaling pathway.