Valacyclovir Mitigates Amyloid Plaque Deposition, P-Tau Aggregation, and Neuroinflammation in Streptozotocin induced Alzheimer's Disease Rat Model

Alzheimer’s Disease (AD), a leading cause of dementia, is a known neurodegenerative disorder. Affecting millions of people worldwide, AD pathogenesis involves diverse risk factors such as lifestyle, environmental, and metabolic conditions that accelerate sporadic AD. Very recently, backed with substantial evidence, herpes simplex virus-1 (HSV-1) has been recognized as a potential causative factor that may play a pivotal role in sporadic AD. Latent virus is estimated to activate key underlying pathways, preferably Aβ and p-tau, to cause AD. Additionally, Antivirals such as Valacyclovir have emerged to impart a potential neuroprotective role in AD. Present research aimed to explore the neuroprotective role and mechanism of Valacyclovir in the streptozotocin-induced Alzheimer’s disease model in rats. A single dose of 3 mg/kg ICV (intracerebroventricular) Streptozotocin (STZ) was administered to induce AD in rats. Two doses of Valacyclovir, i.e., 100 mg/kg and 150 mg/kg were evaluated with Donepezil 5 mg/kg as standard. Post 21 days of treatment, Valacyclovir demonstrated dose-dependent improvement in neurobehavioral parameters. Further, AD-specific parameters i.e. Aβ1-40 and Aβ1-42, p-tau, and BACE-1 were significantly (p < 0.001) reduced with parallel reduction in inflammatory (p < 0.001) and oxidative stress markers. Additionally, Valacyclovir also increased the levels of amyloid clearance enzymes i.e., neprilysin (NEP) (p < 0.001) and insulin-degrading enzyme (IDE) (p < 0.001). Results suggest promising neuroprotective action of valacyclovir via reducing Aβ-amyloid protein, p-Tau, BACE-1, as well as demonstrating anti-inflammatory and antioxidant activity.