Protective effect of hot peppers against amyloid Aβ peptide and brain injury in AlCl3 induced Alzheimer’s disease in rats

Abstract

Objective(s): This study investigated the therapeutic effect of red hot pepper (Capsicum annuum) methanolic extract in induced Alzheimer’s disease using AlCl3 in male rats. Materials and Methods: Rats were injected with AlCl3 intraperitoneally (IP) daily for two months. Starting from the 2nd month of AlCl3, rats received, in addition, IP treatments with Capsicum extract (25, 50 mg/kg) or saline. Other groups received only saline or Capsicum extract at 50 mg/kg for two months. Brain levels of reduced glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA) were determined. Additionally, paraoxonase-1 (PON-1) activity, interleukin-6 (IL-6), Aβ-peptide, and acetylcholinesterase (AChE) concentrations in the brain were measured. Behavioral testing included wire-hanging tests for neuromuscular strength and memory tests such as Y-maze and Morris water maze. Histopathology of the brain was also done. Results: Compared with saline-treated rats, AlCl3 caused significant elevation of brain oxidative stress as GSH level and PON-1 activity were depleted along with MDA and NO level elevation in the brain. There were also significant increases in brain Aβ-peptide, IL-6, and AChE levels. Behavioral testing indicated that AlCl3 decreased neuromuscular strength and impaired memory performance. Capsicum extract given to AlCl3-treated rats significantly alleviated oxidative stress and decreased Aβ-peptide and IL-6 in the brain. It also improved grip strength and memory functioning and prevented neuronal degeneration in the cerebral cortex, hippocampus, and substantia nigra of AlCl3-treated rats. Conclusion: The study suggests beneficial effects for hot peppers through their anti-oxidant and anti-inflammatory actions in halting neurodegeneration in this model of Alzheimer’s disease.

Keywords

• amyloid-β peptide
• anti-oxidant
• capsaicin
• capsicum
• hot pepper
• memory
• neuroprotective