Oral administration of butylated hydroxytoluene induces neuroprotection in a streptozotocin-induced rat Alzheimer’s disease model via inhibition of neuronal ferroptosis

Abstract

Abstract Background Alzheimer’s disease (AD) is the most common human neurodegenerative disorder worldwide. Owing to its chronic nature, our limited understanding of its pathophysiological mechanisms, and because of the lack of effective anti-AD drugs, AD represents a significant socio-economic challenge for all industrialized countries. Neuronal cell death is a key factor in AD pathogenesis and recent studies have suggested that neuronal ferroptosis may play a major patho-physiological role. Since ferroptosis involves free radical-mediated lipid peroxidation, we hypothesized that enteral administration of the radical scavenger butylated hydroxytoluene (BHT) might slow down or even prevent the development of AD-related symptoms in an in vivo animal AD model. Material and methods To test this hypothesis, we employed the rat model of streptozotocin-induced AD and administered butylated hydroxytoluene orally at a dose of 120 mg/kg body weight. Following BHT treatment, neuronal cell death was induced by bilateral stereotactic intraventricular injection of streptozotocin at a dose of 3.0 mg/kg body weight. Three weeks after surgery, we assessed the learning capabilities and the short-term memory of three experimental groups using the conventional y-maze test: (i) streptozotocin-treated rats (BHT pre-treatment), (ii) streptozotocin-treated rats (no BHT pre-treatment), (iii) sham-operated rats (BHT pre-treatment but no streptozotocin administration). After the y-maze test, the animals were sacrificed, hippocampal tissue was prepared and several biochemical (malonyl dialdehyde formation, glutathione homeostasis, gene expression patterns) and histochemical (Congo-red staining, Nissl staining, Perls staining) readout parameters were quantified. Results Intraventricular streptozotocin injection induced the development of AD-related symptoms, elevated the degree of lipid peroxidation and upregulated the expression of ferroptosis-related genes. Histochemical analysis indicated neuronal cell death and neuroinflammation, which were paralleled by aberrant intraneuronal iron deposition. The streptozotocin-induced alterations were significantly reduced and sometimes even abolished by oral BHT treatment. Conclusion Our data indicate that oral BHT treatment attenuated the development of AD-related symptoms in an in vivo rat model, most probably via inhibiting neuronal ferroptosis. These findings suggest that BHT might constitute a promising candidate as anti-AD drug. However, more work is needed to explore the potential applicability of BHT in other models of neurodegeneration and in additional ferroptosis-related disorders.

Keywords

• Neurodegeneration
• Butylated hydroxytoluene
• Oxidative stress
• Cell death
• Lipid peroxidation
• Neuronal dysfunction