ABSTRACT
Aluminum (Al) is an omnipresent mineral element in the environment. The brain is a central target of Al toxicity, being highly susceptible to oxidative damage. Therefore, recognition of drugs or natural products that guard against Al-mediated neuronal cell death is a powerful strategy for prevention and treatment of neurodegenerative disorders. This work aimed to explore the potential of a leaf extract from Harrisonia abyssinica to modulate the neurobehavioral, biochemical and histopathological activities induced experimentally by Al in vivo. Rats subjected to Al treatment displayed a reduction in learning and memory performance in a passive avoidance test accompanied by a decrease in the hippocampal monoamine and glutamate levels in addition to suppression of Bcl2 expression. Moreover, malondialdehyde (MDA), inflammatory markers (TNF-α, IL-1ß), apoptotic markers (caspase-3 and expression of Bax) and extracellular regulated kinase (ERK1/2) levels were elevated along with acetylcholinesterase (AChE) activity, histological changes and marked deposition of amyloid ß plaques in the hippocampus region of the brain tissues being observed in Al-treated animals. Concomitant administration of the high dose of H. abyssinica (200 mg/kg b.w.) restored nearly normal levels of all parameters measured, rather than the low dose (100 mg/kg b.w.), an effect that was comparable to the reference drug (rivastigmine). Molecular docking revealed the appropriate potential of the extract components to block the active site of AChE and ERK2. In conclusion, H. abyssinica leaf extract conferred neuroprotection against Al-induced neurotoxic effects, most likely due to its high phenolic and flavonoid content.
ABSTRACT
Antidepressant drugs are associated with many challenges due to their adverse impacts. Seeking alternatives through medicinal plants could have a great merit in overcoming these deleterious effects. This study was designed to investigate the potential mechanism of curcumin (CUR) in modifying the depression-like behaviour in ovariectomised (OVX) rats, inference with fluoxetine (FLX) and oestradiol (E2 ). The treatments of OVX rats started after 1 month post ovariectomy and proceeded for 1 month. The experimental animals were divided into five groups: sham-operated, OVX-, OVX-FLX (20 mg kg-1 , i.p., daily), OVX-E2 (100 µg kg-1 , i.m., every other day), and OVX-CUR- (100 mg kg-1 , p.o., daily) treated groups. The results showed that CUR modulated the depression-like behaviour using forced swimming test. It improved the serotonin content in many brain regions by upregulating tryptophan hydroxylase-2 and 5-hydroxytryptamine1A,2A receptor messenger RNA (mRNA) and downregulating monoamine oxidase A mRNA in the limbic system. Furthermore, it upregulated aromatase, brain-derived neurotropic factor mRNA, and extracellular-regulated kinase 1/2 protein in the limbic system, relative to FLX and E2, compared with OVX group. In conclusion, CUR appears to be safe and efficient agent as serotonin modulator similar to FLX and neurotrophic agent like E2 , in improving the depression-like behaviour in OVX rats.