Neuroprotective effect of hypothermia on hypoxic-ischemic brain injury in mice / 中国当代儿科杂志

<p><b>OBJECTIVE</b>The study was to investigate the effect of different temperatures during hypoxia on brain injury in mice of different ages.</p><p><b>METHODS</b>Newborn C57/BL6 mice at 7 days or 21 days of life were subjected to left carotid artery ligation followed by exposure with 10% oxygen. The mice were kept in a incubator with a predetermined, constant temperature, either 34 degrees centigrade (Hypothermia group) or 36 degrees centigrade (Normothermia group). Brain injury was evaluated 7 days after hypoxia-ischemia (HI). Active caspase-3 and apoptosis-inducing factor (AIF) expressions in the brain tissue were detected by immunohistochemistry and Western Blot was used to evaluate the phosphor-Akt (P-Akt) expression in the brain tissue at 24 hrs post-HI.</p><p><b>RESULTS</b>Brain injuries, including the cortex, hippocampus, striatum and thalamus injuries, occurred in the Normothermia group at 7 days post-HI. The brain cortex showed cystic cavitation in the postnatal day (P)7 pups mice and laminar infarct of the brain cortex was observed in P21 mice. In the Hypothermia group, the P7 mice did not present with laminar infarct of the cortex and had lower scores of neuropathological lesions in cortex, hippocampus, striatum and thalamus than P7 mice from the Normothermia group (P < 0.01); the cortex injuries were significantly relieved but the injuries of hippocampus, striatum and thalamus in P21 mice were similar to those from the Normothermia group. Active caspase-3 (7.0 +/- 5.6) and AIF positive cells (3.7 +/- 6.2) in the cortex of P7 mice from the Hypothermia group were significantly lower than those of the Normothermia group (51.5 +/- 23.2 and 31.8 +/- 22.4) at 24 hrs post-HI (P < 0.01). Wetstern Blot showed the P-Akt expression was obviously decreased in the ipsilateral hemisphere to the occlusion compared with that of the contralateral hemisphere after HI in the Normothermia group (P < 0.05), while in the Hypothermia group the P-Akt expression was not significantly different between the two hemispheres.</p><p><b>CONCLUSIONS</b>Hypothermia has protective effects against HI insults. The protection was more pronounced for the immature brain than the mature brain.</p>

Changes of Cytokines Measurement in Serum and Cerebrospinal Fluid in Asphyxia Ne onates and Its Relationship with Prognostic / 实用儿科临床杂志

Objective To study the dynamic changes of cytokines including tumor necrosis factor-alpha (TNF-?),interleukin-6 (IL-6),IL-8 in serum and cerebrospinal fluid (CSF) of asphyxia neonates,and to analyze the relationship between cytokines levels and severity of brain damage and neurological outcome. Methods The concentrations of TNF-?,IL-6,IL-8 in serum and CSF were measured by radioimmunoassay in 63 asphyxia neonates. Neurological development was evaluated at 12 months by children′s developmental scale of china.Results The serum concentrations of TNF-?, IL-6,IL-8 were significantly higher in asphyxiated neonates than those in the controls,and they were correlated with the degree of encephalopathy. The level of serum TNF-? was hig-(hest) at the first day and IL-6 was highest at the third day. There was no marked dynamic changes within 5 days in serum IL-8 level. The concentrations of TNF-?,IL-8 in CSF were higher at the first and the third day.The dynamic changes of IL-6 in CSF were similar in serum and they were positively correlated. The serum concentration of IL-6 in severe brain injury group was much higher than those of normal and mild group.The CSF concentration of IL-6 in severe brain injury group was much higher than that of normal group. The CSF concentration of IL-8 in severe brain injury group was much higher than those of the normal and mild group. Conclusions The concentrations of TNF-?,IL-6 and IL-8 are increased both in serum and CSF in asphyxiated neonates which are correlated with severity of hypoxic-ischemic encephalopathy. Cytokine-mediated inflammatory reactions may participate in the mechanism of hypoxic-ischemic brain injury after asphyxiaion.The concentration of IL-6 in serum and IL-6, IL-8 in CSF are correlated with the neurological outcome.

Neuroprotective effect and mechanisms of hypothermia in neonatal rat cerebral hypoxic-ischemic damages / 中华儿科杂志

<p><b>OBJECTIVE</b>Recent studies suggest that hypothermia may be a potential treatment for perinatal hypoxic-ischemic (HI) brain damage. But the mechanisms of this effect are not well known. In the present study, the protective effect of systemic hypothermia as well as effect on apoptosis and associated biochemical events were investigated on neonatal rats with HI brain damage.</p><p><b>METHODS</b>Seven-day-old Wistar rats were subjected to left carotid artery ligation and hypoxia was persisted for 60 min. Immediately at the end of hypoxia, the animals were maintained either at 36 degrees C or 30 degrees C for 10 h at random. Caspase-2, 3 activity in brain homogenate was detected with Western blotting at 24 h post-HI (n = 8 for each group). Immunoactivity of microtubule-associated protein-2 (MAP-2), active caspase-3, apoptosis inducing factor (AIF) and oligonucleotide hairpin probe staining were detected at 72 h post-HI. The infarct volume, neuronal loss in CA(1) sector of hippocampus as well as brain injury scoring were calculated according to MAP-2 staining and hematoxylin and eosin staining.</p><p><b>RESULTS</b>Caspase-2, 3 activities were much higher in the normothermia group [(27.7 +/- 14.7), (94.9 +/- 53.1) pmol/(min.mg protein)] at 24 h post-HI than those of hypothermia [(7.9 +/- 3.4), (21.1 +/- 18.7) pmol/(min.mg protein)] and normal control groups [(7.6 +/- 0.7), (12.9 +/- 0.5) pmol/(min x mg protein)] (P < 0.01). The activities were not significantly different between hypothermia group and normal control group. Western blotting showed that caspase-3 activation process was blocked by hypothermia. The number of active caspase-3 and AIF positive cells in the cortex of ipsilateral hemisphere was much higher in the normothermia group (median: 148.5; 22/field) than that of hypothermia group (median: 48.5; 9/field) (P < 0.05). The number of apoptotic cells as judged by oligonucleotide hairpin probe labeling was much higher in normothermia group (median: 144/field) than that of hypothermia group (median: 133/field) (P < 0.05). The brain injury scoring, infarct volume and neuronal loss in CA(1) area of hippocampus were much less in the hypothermia group [10.4 +/- 2.9; 40.5 +/- 34.8)mm(3); 25.7 +/- 11.5] than that of normothermia group [14.2 +/- 3.5; (73.9 +/- 22.4) mm(3); 37.4 +/- 10.6, P < 0.05].</p><p><b>CONCLUSIONS</b>Systemic hypothermia for 10 h after hypoxia-ischemia seemed to be effective in reducing brain damage and the mechanism is associated with alteration of apoptotic pathway.</p>