Hyperforin Attenuates Scopolamine Induced Alzheimer's Pathology in Rat Model: Abrogation of Caspase-1/11 Mediated Pyroptosis via Inhibition of HMGB1-Mediated RAGE Pathway.

Abstract

Alzheimer's disease (AD) is a neurodegenerative disorder associated with the loss of memory, accumulation of amyloid-beta (Aβ) plaques, and inflammation of the nervous system. Scopolamine, an antagonist of muscarinic receptors, is commonly used to mimic the cognitive and behavioral deficits of AD in laboratory animals. In this study, we aimed to test the neuroprotective properties of hyperforin (HPF), a compound extracted from the St. John's wort plant (Hypericum perforatum), in a scopolamine rat model of AD. Sprague-Dawley rats were divided into four groups: control (saline), scopolamine (10 mg/kg, i.p.), scopolamine + hyperforin (10 mg/kg, p.o. for 7 days), and scopolamine + donepezil. Biochemical, and histopathological assessments were performed. Protein analysis related to inflammation, apoptosis, and the HMGB1/RAGE signaling pathway was performed using Western blotting. IL-1α, levels were measured by ELISA. Nissl staining evaluated neuronal damage in the hippocampus. Hyperforin significantly suppressed the activation of the HMGB1/RAGE signaling axis. Furthermore, hyperforin in this model also suppressed pyroptotic cell death and lowered IL-1α, IL-1β, and IL-18 levels. In addition, HPF reduced Aβ formation by downregulating BACE1 and blocking the activity of inflammasomes composed of canonical and non-canonical caspase-1/11. HPF appears to be a potential therapeutic candidate for neurodegeneration associated with AD, given that hyperforin actively demonstrated neuroprotective effects in a scopolamine-induced AD model, most likely through blocking the HMGB1/RAGE signaling pathway, mitigating neuroinflammation and pyroptosis, and inhibiting Aβ synthesis.