Neuroprotective Effect of Fucoxanthin against Intracerebroventricular Streptozotocin (ICV-STZ) Induced Cognitive Impairment in Experimental Rats
Background: Alzheimer's disease (AD) is a neurological disorder characterized by loss of memory and cognitive functions caused by oxidative stress, neuroinflammation, change in neuro- transmitter levels, and excessive deposition of Aβ(1–42) plaques. Fucoxanthin is a carotenoid with potential antioxidant, anti-inflammatory, and neuroprotective actions. Objective: In the present study, fucoxanthin was employed as a protective strategy in Intracere- broventricular Streptozotocin (ICV-STZ) induced experimental model of cognitive impairment. Methods: STZ was injected twice ICV (3 mg/kg) on alternate days 1 and 3, and Wistar rats were evaluated for the memory analysis using Morris water maze and elevated plus-maze. Fucoxanthin at low 50 mg/kg, p.o. and high dose 100 mg/kg, p.o. was administered for 14 days. All animals were sacrificed on day 29, and brain hippocampus tissue after isolation was used for biochemical (MDA, nitrite, GSH, SOD and Catalase), neuroinflammatory (TNF-α, IL-1β, and IL-6), neurotrans- mitters (ACh, GABA Glutamate), Aβ(1–42) and Tau protein measurements. Results: STZ-infused rats showed significant impairment in learning and memory, increased oxida- tive stress (MDA, nitrite), reduced antioxidant defense (GSH, SOD and Catalase), promoted cy- tokine release, and change in neurotransmitter levels. However, fucoxanthin improved cognitive functions, restored antioxidant levels, reduced inflammatory markers dose-dependently, and res- tored neurotransmitters concentration. Conclusion: The finding of the current study suggests that fucoxanthin could be the promising compound for improving cognitive functions through antioxidant, anti-inflammatory, and neuropro- tective mechanisms, and inhibition of acetylcholinesterase (AChE) enzyme activities, Aβ(1–42) accu- mulation, and tau protein.