Early Regional Response of Apoptotic Activity in Newborn Piglet Brain Following Hypoxia and Ischemia

Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
Neurochemical Research (Impact Factor: 2.59). 01/2011; 36(1):83-92. DOI: 10.1007/s11064-010-0267-3
Source: PubMed


Responses of selected neuroregulatory proteins that promote (Caspase 3 and Bax) or inhibit (Bcl-2, high Bcl-2/Bax ratio) apoptotic cell death were measured in the brain of piglets subjected to precisely controlled hypoxic and ischemic insults: 1 h hypoxia (decreasing FiO₂ from 21 to 6%) or ischemia (ligation of carotid arteries and hemorrhage), followed by 0, 2 and 4 h recovery with 21% FiO₂. Protein expression was measured in cortex, hippocampus and striatum by Western blot. There were no significant differences in expression of Caspase-3 between sham operated, hypoxic and ischemic groups. There were significant regional differences in expression of Bcl-2 and Bax in response to hypoxia and ischemia. The changes in Bcl-2/Bax ratio were similar for hypoxia and ischemia except for striatum at zero time recovery, with ischemia giving lower ratios than hypoxia. The Bcl-2/Bax ratio was also lower for the striatum than for the other regions of the brain, suggesting this region is the more susceptible to apoptotic injury.

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    • "In the brain of newborn piglet, the Bcl-2/Bax ratio was lower in the striatum of asphyxiated animals, suggesting that this brain region may be more susceptible to apoptotic injury. On the other hand, no significant differences in the expression of caspase- 3 were detected between SHAM-operated, hypoxic, and ischemic groups [2]. Recent studies have attributed a possible role for poly(ADP-ribose) polymerase-1 (PARP-1), whose overactivation could induce neuronal cell death, whereas its inhibition by nicotinamide might protect against neuronal damage induced by perinatal asphyxia [3]. "
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    ABSTRACT: Objective: Evaluation of neuronal changes in an animal experimental model of normocapnic hypoxia- reoxygenation. Materials and methods: Fifty male piglets were the study subjects; normocapnic hypoxia was induced in 40 piglets and ten were sham-operated (controls). When bradycardia and/or severe hypotension occurred, reoxygenation was initiated. Animals were allocated in 4 groups according to the oxygen concentration, they were resuscitated with 18%, 21%, 40%, and 100% O2. Persisting asystole despite 10 minutes of cardiopulmonary resuscitation and return of spontaneous circulation were the endpoints of the experiment. Surviving animals were euthanized and brain cortex samples were collected, hematoxylin and eosin-stained, and examined for apoptotic bodies observing 10 consecutive high power fields. Results: Histological examination of the control group did not show any pathological change. On the contrary, apoptosis of neurons was found in 87.5% of treated animals. When specimens were examined according to the oxygen concentration used for resuscitation, we found marked intergroup variability; a higher percentage of apoptotic neurons was observed in piglets of group 4 (100% oxygen) compared to the others (P=0.001). Conclusions: This preliminary data shows that normocapnic hypoxia and reoxygenation in Landrace/Large White piglets resulted in significant histological changes in the brain cortex. The degree of pathological changes in cortical neurons was significantly associated with the oxygen concentration used for reoxygenation, with a higher percentage of apoptotic neurons being observed in piglets reoxygenated with 100% compared to 18% O2 and to 21% O2.
    Full-text · Article · Mar 2014
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    • "This is consistent with the vulnerability of these regions to hypoxic-ischemic injury. However, based on the ratio of Bcl-2/Bax and compared with the cortex and hippocampus, Pirzadeh and colleagues suggested that the striatum was the most susceptible area [24]. "
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    ABSTRACT: Background. The mechanisms involving the initiation of apoptosis after brain hypoxia-ischemia through caspase activation are not fully defined. Oxygen free radicals may be an important mediator of caspase initiation with reactive oxygen species generated by xanthine oxidase (XO) being one potential source. The purpose of this study was to examine the role of XO in apoptosis after global cerebral injury. Methods. Immature rabbits were subjected to 8 minutes hypoxia and 8 minutes ischemia and then 4 hours of reperfusion. In one group ( 𝑛 = 5 ), the XO substrate xanthine was infused to generate more oxygen free radicals to promote apoptosis while in another ( 𝑛 = 5 ), the XO inhibitor allopurinol was given to reduce apoptosis by preventing free radical production ( 𝑛 = 5 ). Control animals ( 𝑛 = 4 ) received the vehicles. Caspase 3, 8, and 9 enzyme activities were measured in the cerebral cortex, hippocampus, cerebellum, thalamus, and caudate. Results. Administration of xanthine increased ( 𝑃 < 0 . 0 5 ) caspase 3 activity but only in the hippocampus, and pretreatment with allopurinol did not reduce it. No differences ( 𝑃 > 0 . 0 5 ) were found in any other region nor were there any changes in caspases 8 or 9 activities. Conclusion. We conclude that XO is not a major factor in inducing apoptosis after hypoxic-ischemic brain injury.
    Full-text · Article · Aug 2013
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    • "The data presented in this paper show that, in the striatum of newborn piglets, hypoxic insult results in rapid changes in expression of many proteins believed to regulate the processes that both promote and prevent apoptotic cell death. Striatum was chosen for this study because we have shown earlier that this region is particularly sensitive to hypoxia [12]. This was manifested by significant decrease in Bcl-2/Bax ratio, an indicator of an increased susceptibility of cells to apoptosis. "
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    ABSTRACT: The levels of selected neuroregulatory proteins that inhibit or promote apoptotic cell death were measured in the striatum of piglets subjected to precisely controlled 1 h hypoxic insult followed by 0, 2 and 4 h recovery and compared to sham operated animals. The anti-apoptotic proteins: there were increases in Survivin at 0 (157%, P = 0.031) and 4 h (171%, P = 0.033), in Bcl-XL at 0 (138%, P = 0.028) and 4 h (143%, P = 0.007), in VEGF at 4 h (185%, P = 0.019) and Hsp27 at 2 h (144%, P = 0.05) and 4 h (143%, P = 0.05). The pro-apoptotic proteins: caspases-1 and 7 increased at 4 h (135%, P = 0.05) and (129%, P = 0.038), respectively. Bim increased after 4 h (115%, P = 0.028), Apoptosis Inducing Factor after 2 h (127%, P = 0.048) and Calpain after 4 h (143% of control, P = 0.04). Hypoxia causes increase in levels of both anti- and pro-apoptotic proteins. Their relative activity determines the outcome in terms of cell damage and neuronal deficit.
    Preview · Article · May 2011 · Neurochemical Research
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