Protective effect of hot peppers against amyloid β peptide and brain injury in AlCl(3)-induced Alzheimer’s disease in rats

OBJECTIVE(S): This study investigated the therapeutic effect of red hot pepper (Capsicum annuum) methanolic extract in induced Alzheimer’s disease using AlCl(3) in male rats. MATERIALS AND METHODS: Rats were injected with AlCl(3) intraperitoneally (IP) daily for two months. Starting from the 2nd month of AlCl(3), rats received, in addition, IP treatments with Capsicum extract (25 and 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, AlCl(3) 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 AlCl(3) decreased neuromuscular strength and impaired memory performance. Capsicum extract given to AlCl(3)-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 AlCl(3)-treated rats. CONCLUSION: Short-term administration of ASA (50 mg/kg) has adverse effects on male reproductive function in mice. Co-administration of melatonin protects against ASA-induced impairment of male reproductive function by preventing the reduction in serum TAC and testosterone levels seen with ASA treatment alone.