melissa officinalis acidic fraction protects cultured cerebellar granule neurons against beta amyloidinduced apoptosis and oxidative stress

Objective: extracellular deposition of the beta-amyloid (aβ) peptide, which is the main finding in the pathophysiology of alzheimer’s disease (ad), leads to oxidative damage and apoptosis in neurons. melissa officinalis (m. officinalis) is a medicinal plant from the lamiaceae family that has neuroprotective activity. in the present study we have investigated the protectiveeffect of the acidic fraction of m. officinalis on aβ-induced oxidative stress and apoptosis in cultured cerebellar granule neurons (cgn). additionally, we investigated a possible role of the nicotinic receptor. materials and methods: this study was an in vitro experimental study performed on mice cultured cgns. cgns were pre-incubated with different concentrations of the acidic fraction of m. officinalis for 24 hours, followed by incubation with aβ for an additional 48 hours. cgns were also pre-incubated with the acidic fraction of m. officinalis and mecamylamin, followed by incubation with aβ. we used the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (mtt) assay to measure cell viability. acetylcholinesterase (ache) activity, reactive oxygen species (ros) production, lipidperoxidation, and caspase- 3 activity were measured after incubation. hochst/annexin v- fluorescein isothiocyanate (fitc)/propidium iodide (pi) staining was performed to detect apoptotic cells. results: the acidic fraction could protect cgns from aβ-induced cytotoxicity. mecamylamine did not abolish the protective effect of the acidic fraction. ache activity, ros production, lipid peroxidation, and caspase-3 activity increased after aβ incubation. preincubation with the acidic fraction of m. officinalis ameliorated these factors and decreased the number of apoptotic cells. conclusion: our results indicated that the protective effect of the acidic fraction of m. officinalis was not mediated through nicotinic receptors. this fraction could protect cgns through antioxidant and anti-apoptotic activities.