[Protective effects of Melissa officinalis extract against beta-amyloid-induced oxidative stress in PC12 cells]

The accumulation of beta-amyloid peptide [Abeta] in the brain, is the main characteristic of Alzheimer's disease [AD] that cause oxidative stress and neurotoxicity. Melissa officinalis can protect cells against oxidative damages. This plant is also used in traditional medicine as a memory enhancer and diseases that are associated with neurological disorders. This study investigated the effects of ethanolic extract of Melissa officinalis on Abeta induced neurotoxicity and its antioxidant mechanism. Aerial parts of Melissa officinalis were extracted with ethanol 80% using maceration method. PC12 cells were incubated with the extract prior to incubation with Abeta and cell toxicity, production of reactive oxygen species [ROS], lipid peroxidation and glutathione peroxidase activity were measured 24 h later. Incubation of PC12 cells with Abeta significantly caused cell death in PC 12 cells, this was accompanied by increasing in ROS and lipid peroxidation but decreasing in glutathione peroxidase activity. Pretreatment with Melissa officinalis extract significantly protected PC 12 cells against Abeta induced toxicity and attenuated Abeta induced changes in oxidative stress biomarkers in PC 12 cells. Melissa officinalis extract, prevents Abeta induced neurotoxicity through attenuating oxidative stress. It may act as an ROS scavenger and can be a candidate for AD therapy

Effects of training in the Morris water maze on the spatial learning acquisition and VAChT expression in male rats

It has been well established that cholinergic pathway plays an important role in learning and memory processes. The present study was designed to evaluate the effects of Morris water maze [MWM] training on spatial memory acquisition and expression of the vesicular acetylcholine transporter [VAChT] in male rats. Methods: In this study, training trials of all groups of animals were conducted in the MWM task. Rats received one training session consisting of four trials per day which continued for another four consecutive days. Controls received visible platform MWM training. The escape latency, the traveled distance and swimming speed for each rat were recorded and used to evaluate the performance of the animal during training period. For evaluation of expression of VAChT protein levels, brain tissues from animals in each experiment were obtained immediately after the last trial on the related experimental day and processed for immunohistochemistry staining and western blotting analysis. There was a significant difference between animals subjected to one day training and those receiving four days of training in escape latency and travel distance. There were an apparent increase in VAChT immunoreactivity in the medial septal area [MSA] and CA1 region of the hippocampus in one day and four day trained animals compared with controls [visible group]. Quantitative immunostaining analysis by optical density measurements in the CA1 region and evaluation of immunopositive neurons in medial septal area of brain sections confirmed qualitative findings. Assessment of VAChT protein level expression in hippocampus by western blotting evaluation showed the same pattern of immunohistochemistry results. Overall, results of this study reveal changes in cholinergic neuron activity in different stages of training in the MWM task. Data suggest that there is a significant level of cholinergic neuronal activity during early stages of the training especially in the hippocampus region that may contribute to the apparent increase in VAChT expression