| Recently, Some studies have shown that cigarette smoking is related to some diseases of nervous system. Epidemiological study has shown that cigarette smoking is a major risk factor for stroke, especially for ischemic stroke. The research in foreign country found that smoking could accelerate the brain atrophy and degeneration.Apoptosis is a kind of death form that cell can end its life actively according to some established program under the physiologic or pathologic conditions, and it is a multistage genetic mechanism under the gene control. Apoptosis is important to the compliance and normal development of nervous system. Pathologic apoptosis can occur in nerve cell under some stimulus, and it can consider to be associated with some kinds of nervous system diseases, such as presenile dementia, ischemic brain damage, nervous degenerative disease, etc. Apoptosis has complex molecular control mechanism, and Fas ( Apo - 1 or CD95 ) is a kind of receptor at the surface of the cell that can transmit death signal. A lot of experiment both in vivo and in vitro have demonstrated that Fas can mediate apoptosis. Fas/Fas ligand is an important kind of apoptosis signal transmitting system.Some studies have shown that cigarette smoking can induce kinds of tissues apoptosis, but whether it can induce nerve cell apoptosis have not been reported. This study used terminal in situ nick end la-beling TUNEL and immunohistochemical methods to observe the smoking - induced apoptosis and Fas protein expression in rat brain, also discussed the variation pattern and possible mechanism in order to provide the theoretic foundation to smoking - induced brain damage and its therapy.Materials and methodsLaboratory animals were distributed randomly into 5 groups -chronic and large - dose smoking group, chronic and small - dose smoking group, short - term smoking group, anti - smoking group and control group. Animal model of smoking and Specimen were made, HE dying and observing with light microscope. Used terminal in situ nick end labeling TUNEL and immunohistochemical SABC methods to detect apoptosis and Fas protein expression. Used microscope counting method to count the positive cells, and used SPSS 10. 0 software to process data. Analysis of variance was used to compare the data of different groups.Results1. There were few apoptotic cells and small amount of Fas protein in control group. 2. Compared with the control group, apoptosis and Fas protein expression in chronic and short - term smoking group were significantly increased (P<0.01). 3. Apoptosis and Fas protein expression in anti - smoking group were significantly decreased compared with short - term group ( P < 0. 01) , there was no significant difference between anti - smoking group and control group (P > 0.05 ). 4. Apoptosis in chronic and large - dose group was significantlyincreased compared with the chronic and small - dose group and short- term groups (P<0.01). 5. Fas protein expression in chronic andlarge - dose group was significantly increased compared with the short- term groups ( P < 0. 01) , and there was no significant difference between it and chronic and small - dose group ( P > 0.05).DiscussionApoptosis was brought forward in 1972 by Kerr, and then became the research hotpot of each subject. Apoptosis is associated with some nervous system diseases, such as ischemic brain damage, nervous degenerative disease, etc. Diverse factors can induce apoptosis such as deficiency of growth factor, radiation, etc. It has been demonstrated that cigarette smoking and cigarette smoke exposure can induce apoptosis in different tissues.This study showed that there were few apoptotic cells in normal rat brain, and cigarette smoking could significantly elevate apoptosis in brain tissue, most of apoptotic cells were nerve cells. The number of apoptotic cell in brain tissue was increased with the increasing of smoking time and daily smoke dose. It suggested that there was time- effect and dose - effect relationship between cigarette...
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