Resveratrol Maintains Hippocampal Mitochondrial Function and Inhibits Neuronal Ferroptosis to Improve Diabetes-Associated Cognitive Dysfunction via Sirt1/Shh Signaling

Background Resveratrol has been shown to play a neuroprotective role in diabetic cognitive dysfunction. We determined whether resveratrol improved diabetic cognitive dysfunction through ferroptosis regulation, and explored the potential mechanism. Methods Rats were fed with a high-sucrose and high-fat diet combined with streptozotocin for establishing a diabetic model, followed by resveratrol treatment with or without erastin (a classical ferroptosis activator). Cognitive abilities were evaluated with novel object recognition test and Morris water maze test. Neuronal damage was determined using Nissl staining and Fluoro-Jade B staining. Ferroptosis-related factors such as glutathione (GSH), 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), superoxide dismutase (SOD), reactive oxygen species (ROS) and iron (Fe 2+ ) levels were evaluated. Mitochondrial function was assessed by mitochondrial morphology, mitochondrial swelling, mitochondrial membrane potential (MMP), and ATP content. Western blot was performed to measure Sirtuin 1 (Sirt1) and Sonic hedgehog (Shh) signaling pathway, and ferroptosis-related proteins. Besides, the cellular localization of Sirt1 and Shh was assessed using immunofluorescence. Results Resveratrol ameliorated cognitive dysfunction and neuronal damage in diabetic rats and blocked hippocampal neuron ferroptosis, which were abolished by erastin. Resveratrol ameliorated hippocampal mitochondrial dysfunction (decrease of mitochondrial swelling and increases of MMP and ATP) in diabetic rats. Resveratrol treatment upregulated Sirt1 and Shh expressions in NeuN-positive neurons in the hippocampus of diabetic rats. Moreover, Shh knockdown reversed the protective effects of resveratrol on ferroptosis, cognitive dysfunction, and neuron loss. Conclusion Resveratrol conferred neuroprotective effect on diabetic cognitive dysfunction by maintaining mitochondrial function and inhibiting hippocampal neuron ferroptosis via Sirt1/Shh signaling.