| Alzheimer's disease (AD) is the most common type of dementia. Recent studies suggest that the appearance of activated-microglia is another characteristic of AD. Microglia, the main immune cell of the central nervous system (CNS), plays critical role as resident immunocompetent and phagocytic cells in CNS. During the inflammatory processes in CNS, activated microglia can be induced by many factors. Activation of microglia induces the release of some neurotoxic substances such as nitric oxide (NO) and TNF-alpha (TNF-α), which induce neuronal death directly or indirectly.In the present study, the protecting effects of the 9 natural compounds, which were extracted from ginsen or grape seed, on rat cortical neuron damage induced by lipopolysaccharides (LPS)-activated microglia were investigated.Firstly the conditioned medium collected from normal or LPS-activated N9 microglia (C-CM and L-CM, respectively) was used to estimate whether it can damage rat cortical neuron or not. The viability of neurons was detected by MTT assay. The study of the time-course and concentration dependent neurotoxic effect of L-CM indicated that the viability of neuron treated with 100% L-CM for 24 h was decreased significantly. Then, the neuroprotective effect of Minocycline, one of the anti-inflammatory agents, was studied. The results showed that minocycline can inhibit the activation of N9 cell induced by LPS in a concentration dependent manner and the conditioned medium collected from the N9 cells treated with LPS and minocycline can reverse the neuronal damage induced by microglia activation, which suggested the model proves that microglia activation can make neuron damaged in some pathological states and can be used to measure the neuroprotective effect of the natural compounds.Secondly, the mechanism of the neuronal injury in this model was then studied. H2O2 in sublethal concentration aggravated neuron death in cultures pre-exposed to LPS-activated N9...
|
PDF Full Text Request