| Microglial cells are considered to be "macrophages of the central nervous system",which play an important role in the inherent immune response. Cerebral ischemia or brain injury can induce the activation of microglial cells, and the activated microglial cells will release cytotoxins, inflammatory mediators and cytokines. Interleukin 1 (IL-1β) is one of cytokines, which is generated in early period of inflammation. It can induce and enhance the inflammatory cascade reaction. It also can up-regulate the expression of adhesion factors in coordination with nuclear factorκB (NF-κB), tumor necrosis factor a (TNF-a) and interferon y (IFN-γ) which involve in inflammatory reaction after ischemia, and result in cell apoptosis in the end. It has been found that Naoxintong could inhibit microglial activation and reduce the incidence of apoptosis by decreasing IL-1βrelease.Objective:To investigate the possible protective effects of the Naoxintong CapsuleManual on neuronal apoptosis in rat model of middle cerebral artery occlusion (MCAO);To investigate the mechanisms of Naoxintong CapsuleManual in antagonizing neuronal apoptosis, by its possible actions on microglia activation and the expression of inflammatory mediators (IL-1).Methods:1. Middle cerebral artery occlusion (MCAO) model of rat was set up by a modified Zea-Longa method. Animals were anesthetized by intraperitoneal injection of 10% chloral hydrate (300mg/kg), then we did the neck median incision, ligated the distal end of the left external carotid artery and heat cured its branches, put bulldog clamp to occlusion common carotid artery and internal carotid artery, inserted strong fishing line about 0.24-0.26mm in diameter with the distal coated with paraffin wax after disconnecting the external carotid artery, the depth was on the points away from the common carotid artery fork at the (18+/-0.5mm), then sutured the skin, pulling the fishing line to the external carotid artery stump after 90 minutes. In the sham operation group the strong fishing line insert into 9mm, which would not be blocked, the remaining steps were the same as that of the ischemia group. 2. The powder of Naoxintong CapsuleManual was dissolved in distilled water. The dosage was determined by transition formula from human to animal on the basis of its clinical dose. Naoxintong CapsuleManual was administered by oral feeding to the treatmented group, in a dosage of 0.14g/kg, two times one day (10ml/kg). The control group and the sham group were given the distilled water in the same amount. The duration was two weeks. The models were established one hour after last administration.3. Microglial activation was detected by CD68 immunohistochemistry.4. Expression of IL-1βof Inflammatory mediators were analysised by Western blot.5. Neuronal apoptosis of rats was detected by TUNEL, Nissl stainning.Results:1. Microglia activation and the expression of IL-1β:Large number of brown stained activated microglia distributed in the focal zone by CD68 immunohistochemistry. Microglial cells in the control group were obviously more than those in the sham operated group and treatmented group. Microglial activation significantly reduced in the treatmented group. Simultaneously, the expression of inflammatory cytokines IL-1βin the treatmented group and the sham operated group were significantly lower than that in the control group.2. Detection of apoptosis:, The Naoxintong treatmented group could significantly reduce the occurrence of apoptosis by TUNEL and Nissl staining.Conclusions:Cerebral ischemia or brain injury can induce the activation of microglia. Microglial activation resulted in the release of inflammatory mediators IL-1β, and leaded to cell apoptosis in the end. Naoxintong could repress inflammation reaction by inhibiting microglia activation and decreasing IL-1βexpression, then protect neuronal cells from apoptosis.Significance:This study further confirmed the important role of microglia in inflammatory reaction and cell apoptosis after cerebral ischemia. Most importantly, it was found that Naoxintong could prevent the activation of microglial cells and inhibit the expression of inflammatory cytokines, reducing the occurrence of apoptosis.
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