Protective effect of hot peppers against amyloid Aβ peptide and brain injury in AlCl۳ 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 AlCl۳ in male rats. Materials and Methods: Rats were injected with AlCl۳ intraperitoneally (IP) daily for two months. Starting from the ۲nd month of AlCl۳, rats received, in addition, IP treatments with Capsicum extract (۲۵, ۵۰ mg/kg) or saline. Other groups received only saline or Capsicum extract at ۵۰ mg/kg for two months. Brain levels of reduced glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA) were determined.  Additionally, paraoxonase-۱ (PON-۱) activity, interleukin-۶ (IL-۶), 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, AlCl۳ caused significant elevation of brain oxidative stress as GSH level and PON-۱ activity were depleted along with MDA and NO level elevation in the brain. There were also significant increases in brain Aβ-peptide, IL-۶, and AChE levels. Behavioral testing indicated that AlCl۳ decreased neuromuscular strength and impaired memory performance. Capsicum extract given to AlCl۳-treated rats significantly alleviated oxidative stress and decreased Aβ-peptide and IL-۶ in the brain. It also improved grip strength and memory functioning and prevented neuronal degeneration in the cerebral cortex, hippocampus, and substantia nigra of AlCl۳-treated rats. Conclusion: Short-term administration of ASA (۵۰ 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.

Keywords:

Amyloid-Β peptide , Anti-oxidant , Capsaicin , Capsicum , Hot pepper , Memory , Neuroprotective