Intermittent Hypoxia On The Cerebral Cortex Of Developing Rats C-FOS, BAX Expression

Objective: Using HE staining, Toluidine blue staining, immunohistochemistry technique, electron microscopy and other methods, observe the cerebral cortex of developing rat C-FOS,BAX expression under different conditions For intermittent hypoxia on the developmental stages in rat brain protective mechanism to provide morphological evidence.Materials and Methods: To newborn male Sprague-Dawley rats were randomly divided into 28 days, 42 days, 56 days ,the three groups. Each group is further divided into control group, acute hypoxia group, intermittent hypoxia group,intermittent hypoxia and acute hypoxia group, the four groups, a total of 12 group. Control group animals did not receive any treatment, acute hypoxia animals taken prior to the mixed gas (10% oxygen +90% nitrogen) for 10 minutes. Intermittent hypoxia animals (together with the pregnant animals) in low-pressure chamber, respectively 28 days,42 days,56 days equivalent to 3000 meters of decompression hypoxia treatment, five hours every day. The rats were anaesthetized with pentobarbital, heads were transsected and the cerebral parietal cortex were removed. Brain tissues were taken with 4% polyformaldehyde embedded with paraffin and sectioned as usual. Methods of light microscope, electron microscope and immunohistochemistry were involved in this study.Results:1 HE staining and Toluidine blue staining:There was no significant difference between Control group and intermittent hypoxia group. Given after acute hypoxia, we can see neurons showed different degrees of injury degenerative changes ,cerebral cortex showed normal structure of the destruction of nerve cell swelling or disappeared, translucent cytoplasm, disappearance of Nissl body dissolution, nuclear deviation. At the same time can see the neurons shrink, nucleus pyknosis, cells were triangular. Cells around the gap widened significantly and the impaired cells were shaped vacuoles. Add to give acute hypoxia after intermittent hypoxia, Parietal cortex neurons of the brain can be seen a certain degree of pathological damage, manifested as swelling cell body, Nissl bodies margination. Significantly reduce the hypoxic injury, the results showed that intermittent hypoxia has a protective effect on the brain.2 Bax: BAX protein immunoreactive cells in yellow,which are mainly located in cytoplasm, the nucleus can also be seen, staining was granular or cords. 56 days in control group:the positive products were not common,the optical density(OD) was 0.1239±0.0054. 56 days of intermittent hypoxia group: Change was not obvious, the optical density(OD) was 0.1229±0.0046, P>0.05. 56 days of intermittent hypoxia and acute hypoxic group: BAX protein expression gradually increased, the optical density(OD) was 0.2629±0.0029, P<0.01. 56 days of acute hypoxia group: BAX expression was significantly increased,the optical density(OD) was 0.3449±0.0047, P<0.01. 42 days group,28 days group trend with the same 56 days group.There were no significant differences in BAX immunoreactive protein expression between the control group, intermittent hypoxia and acute hypoxia group . Intermittent hypoxia and acute hypoxic group, 28 days group :The positive expression are obvious, the optical density(OD) was 0.2020±0.0017. 42 days group: Bax protein expression increased apparently, the optical density(OD) was 0.2617±0.0058 ,P<0.01. 56 days group : the optical density(OD) was 0.2629±0.0029, P<0.01.Among them, there is no significant change between 42 days group and 56 days group.3 C-FOS: Immunoreactive product were brown, which are located in the nucleus, cytoplasm blank. 28 days in control group: the positive products were not common, the Positive cell rates was 38.34±0.20. 28 days of intermittent hypoxia group: Change was not obvious, the Positive cell rates was 38.32±0.23, P>0.05.28 days of intermittent hypoxia and acute hypoxic group: the number of positive neurons increased apparently, the Positive cell rates was 47.43±0.30, P<0.01. 28 days of acute hypoxia group: C-FOS protein expression increased significantly and the positive neurons were all over the field, the Positive cell rates was 80.27±0.28, P<0.01. 42 days group,56 days group trend with the same of 28 days group.There were no significant differences in BAX immunoreactive protein expression between the control group, intermittent hypoxia and acute hypoxia group . Intermittent hypoxia and acute hypoxic group, 28 days group : the Positive cell rates was 47.43±0.30。42 days group: C-FOS protein expression increased apparently, the Positive cell rates was 54.39±0.28, P<0.01. 56 days group : the Positive cell rates was 54.45±0.30, P<0.01. Among them, there is no significant change between 42 days group and 56 days group.4 Ultrastructural changes : There was no significant difference between Control group and intermittent hypoxia group. Given after acute hypoxia, Neuron degeneration obvious Karyopyknosis, folded nuclear membrane, chromatin often reduced below the nuclear membrane appears set situation.Rough endoplasmic reticulum obvious expansion, edema, degranulation; mitochondrial swelling, cristae broken, dissolved, disappeared. Synaptic structure of the destruction of small synaptic vesicles, rupture and even integration, to reduce the disappearance of cristae-like vacuoles were, fuzzy synaptic cleft, before and after the membrane was not obvious. Add to give acute hypoxia after intermittent hypoxia, Nerve cells in rough endoplasmic reticulum, Golgi complexes mild expansion. Mitochondrial swelling, cristae fuzzy disorder. Presynaptic component of synaptic vesicles accumulate, and are mostly located in surrounding. Synaptic membrane before and after thinning, narrow synaptic cleft, mitochondrial swelling.Compared with acute hypoxia group, given to intermittent hypoxia, the hypoxic injury was significantly reduced .Conclusions: Acute cerebral hypoxia-stimulated neurons show varying degrees of injury which can induce to C-FOS, BAX protein widely express. At the same time to give intermittent hypoxia can effectively reduce C-FOS, BAX protein expression, Play a role in the protection of the brain.Hypoxic injury in younger rat brain is more tolerated.