Brain Damage In Neonatal Rats Research Articles

Prophylactic administration of melatonin to the mother throughout pregnancy can protect against oxidative cerebral damage in neonatal rats

Objective: The purpose of this study was to investigate whether prophylactic administration of melatonin to the mother throughout pregnancy could protect against ischemia/reperfusion (I/R)-induced oxidative brain damage in neonatal rats. Methods: The utero-ovarian arteries were occluded bilaterally for 30 min in female Wistar rats on day 16 of pregnancy to induce fetal ischemia. Reperfusion was achieved by releasing the occlusion and restoring circulation. A sham operation was performed in control rats. Melatonin solution or vehicle alone was administrated orally throughout pregnancy. We collected brain mitochondria from neonatal rats, evaluated mitochondrial structure by electron microscopy, and measured the respiratory control index (RCI) as an indicator of mitochondrial respiratory activity as well as the concentration of thiobarbituric acid-reactive substances (TBARS), a marker of oxidative stress. Histological analysis was performed at the Cornu Ammonis 1 (CA1) and Cornu Ammonis 3 (CA3) regions of the hippocampus. Results: I/R significantly reduced the RCI and significantly elevated the concentration of TBARS. Melatonin treatment reversed these effects, resulting in values similar to that in untreated, sham-ischemic animals. Electron microscopic evaluation showed that the number of intact mitochondria decreased in the I/R group, while melatonin treatment preserved them. Histological analysis revealed a decrease in the ratio of normal to whole pyramidal cell number in the CA1 and CA3 regions in the I/R group. While melatonin administration protected against degeneration. Conclusions: These results indicate that prophylactic administration of melatonin to the mother throughout pregnancy may prevent I/R-induced oxidative brain damage in neonatal rats.

Protective effects of bubble bath hydrotherapy on brain damage of neonatal rats with recurrent seizures

Objective To explore the potentiality of protection by bubble bath hydrotherapy to brain damage of neonatal rats with recurrent seizures.Methods Sixty Sprague-Dawley neonatal rats were randomly divided into control group ( CON),control hydrotherapy group ( HCON ),recurrent-seizure group (RS) and recurrent-seizure hydrotherapy group (HRS).Each group had 15 rats.The volatile agent flurothyl was used to induce 30 min seizure attack.At postnatal day 6 (P6),recurrent seizures were induced once per day for consecutive 6 days in the RS group and HRS group.Rats in the CON and HCON group were placed into the container for same time as their counterpart without exposure to flurothyl.In HCON and HRS groups,Bubble bath hydrotherapy intervention was used after the end of the last seizure for 28 consecutive days.Inspections were made for maturation of physical characteristics,neural behavior.PRG-1 and Bcl-2 protein level in cerebral cortex were detected by western blot method at P50.Results 1.Maturation of physical characteristics:body weights of the rats in the RS group were decreased significantly (P＜0.05).Body weights of HRS rats were significantly increased than that of RS rats(P＜0.05 ).There were no significant difference of physiological development phenomenon among the five groups (P ＞0.05 ).2.There was high nerve excitation in hydrotherapy group ( At P26,the scores of OFT respectively were 45.78 ± 18.31 for CON,59.78 ± 25.61 for HCON,27.78 ± 16.83 for RS and 53.15 ± 22.43 for HRS,P ＜ 0.01 ).3.The expression of PRG-1 in cerebral cortex of RS group were significantly higher than that of CON group (1.149 ±0.191 for RS,0.910 ±0.162 for CON,P＜ 0.05 ).The level of Bcl-2 in cerebral cortex of RS group ( 1.149 ±0.191 ) were significantly lower than that of CON group( 1.259 ±0.157) (P＜0.05 ),the level of Bcl-2in cerebral cortex of HRS group( 1.572 ± 0.333 ) were significantly higher than that of RS group(P＜ 0.05 ).Conclusion Maturation of physical characteristics and neurobehavioral were damages following recurrent neonatal seizures,which may be associated with significantly increased level of PRG-1 protein and decreased level of Bcl-2protein in cerebral cortex.The early intervention by Bubble bath hydrotherapy can play a positive role on developmental rehabilitation. Key words: Neonatal; Seizure; Bubble bath hydrotherapy; Neurobehavioral; PRG-1; Bcl-2

Effects of extracellular-signal regulated kinase signaling pathway activation on hypoxic-ischemic brain damage of neonatal rats

Objective To investigate the effects of extracellular-signal regulated kinase (ERK) on hypoxic-ischemic brain damage of neonatal rats.Methods The hypoxic-ischemic brain damage model of neonatal Wistar rats was established as following:first the right common carotid artery of the rats was ligated;2 h after operation,the rats began to inhale 8%-oxygen oxygen-nitrogen gas mixture lasting for 2 h.Rats were randomly divided into three groups:sham-group,hypoxic-ischemic group and ERK inhibitor PD98059 group (the rats were injected PD98059 2 mg/kg 10 min before the ligation).Six hours after the models were done,hippocampi and cortex of the ligation side of rats in the three groups were collected,and the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were measured.Apoptosis of neuron was assessed by TUNEL staining.The expression of ERK1,ERK 2,Bcl-2 and Bax were examined by Western blot.The differences among the groups were analyzed with ANOVA and q test.Results Compared with the sham-group,the MDA level [(342.9± 10.8) μmol/L vs (181.5± 17.0) μmol/L,q= 6.35,P＜0.01) and the apoptosis rate of neuron [(18.80±1.37)% vs (3.53±0.34)%,q=6.06,P＜0.01) of hypoxic-ischemic group was higher,and SOD level was lower [(34.8±4.3) U/ml vs (63.4±4.3) U/ml,q=4.99,P＜0.01].While the apoptosis rate of neuron [(15.53±0.64) %] and MDA level [(252.0± 17.1) μmol/L] of PD98059 group were lower than those of hypoxic-ischemic group(q=3.87 and 5.28,P＜0.01respectively),the SOD level [(51.5 ± 3.8) U/ml] was higher than that of hypoxic-ischemic group (q=4.17,P＜0.01).There were no differences of ERK1 and ERK2 expressions among the three groups.The phosphorylated ERK1 and ERK2 levels of hypoxic-ischemic group were higher than those of sham-group (q=3.82 and 4.08,P＜0.01) and PD98059 group (q=4.79 and 5.12,P＜0.01).The expression of Bcl-2 and Bax of hypoxic-ischemic group were higher than those of sham-group (q=3.55 and 3.42,P＜0.01).Compared with hypoxic-ischemic group,Bcl-2 expression (q=3.71,P＜0.01) of PD98059 group was higher,and Bax expression (q=5.86,P ＜ 0.01) was lower.Conclusions ERK is involved in hypoxic-ischemic brain damage of neonatal rats through regulating the expression of apoptosis protein. Key words: Hypoxia-ischemia,brain; Extracellular-signal regulated MAP kinases; Animals,newborn; Rats; Apoptosis

Neuroprotective Effect of Inhaled Nitric Oxide on Excitotoxic-Induced Brain Damage in Neonatal Rat

BackgroundInhaled nitric oxide (iNO) is one of the most promising therapies used in neonates. However, little information is known about its impact on the developing brain submitted to excitotoxic challenge.Methodology/Principal FindingsWe investigated here the effect of iNO in a neonatal model of excitotoxic brain lesions. Rat pups and their dams were placed in a chamber containing 20 ppm NO during the first week of life. At postnatal day (P)5, rat pups were submitted to intracranial injection of glutamate agonists. At P10, rat pups exposed to iNO exhibited a significant decrease of lesion size in both the white matter and cortical plate compared to controls. Microglia activation and astrogliosis were found significantly decreased in NO-exposed animals. This neuroprotective effect was associated with a significant decrease of several glutamate receptor subunits expression at P5. iNO was associated with an early (P1) downregulation of pCREB/pAkt expression and induced an increase in pAkt protein concentration in response to excitotoxic challenge (P7).ConclusionThis study is the first describe and investigate the neuroprotective effect of iNO in neonatal excitotoxic-induced brain damage. This effect may be mediated through CREB pathway and subsequent modulation of glutamate receptor subunits expression.

Adenoviral vector-mediated transduction of VEGF improves neural functional recovery after hypoxia-ischemic brain damage in neonatal rats

Previous studies have showed that vascular endothelial growth factor (VEGF) displayed neurotrophic and neuroprotective activities. To examine whether target delivery of VEGF gene directly into brain may prevent ischemic brain damage, the VEGF expression adenoviral vectors, AVHP.VEGF-with 476 bp of the human preproendothelin-1 (ppET-1) promoter and 35 bp of the hypoxia-reponse element (HRE) driving VEGF expression and CMV.VEGF were transferred into hypoxic-induced ischemic (HI) rat brains. Seven-day-old rats that were underwent left carotid ligation followed by 2 h of hypoxic stress (8% O 2 at 37 °C) were received VEGF adenoviral vectors or buffer (PBS) injection 3 days after HI. The body weight, VEGF expression, neuronal apoptosis, cerebral morphology and brain functional assays were performed between 7 and 28 days after HI. There were remarkable increases in the body weight and VEGF protein expression, and decrease in the number of TUNEL-positive cells in the VEGF vector groups as compared with PBS group. The VEGF vector groups also had better brain functional performs than PBS group. The better performs by the animals that received VEGF vectors may be directly linked to the inhibitory effect of VEGF on neuronal apoptosis because the animals had less neural loss in the cortex and hippocampal CA1 region as compared with PBS group. Overall, these results indicated that over-expression of VEGF in the brain exerted a neuroprotective effect and promoted neural functional recovery in neonatal rats after hypoxic–ischemic brain damage, suggesting that in vivo target VEGF gene transfer to brain may be a promising approch for the treatment of such implications.

IFATS Collection: The Conditioned Media of Adipose Stromal Cells Protect Against Hypoxia-Ischemia-Induced Brain Damage in Neonatal Rats

Adipose tissue stroma contains a population of mesenchymal stem cells, which support repair when administered to damaged tissues, in large part through secreted trophic factors. We directly tested the ability of media collected from cultured adipose-derived stem cells (ASCs) to protect neurons in a rat model of brain hypoxic-ischemic (HI) injury. Concentrated conditioned medium from cultured rat ASCs (ASC-CM) or control medium was infused through the jugular vein of neonatal Sprague-Dawley rats subjected to HI injury. The ASC-CM was administered either 1 hour before or 24 hours after induction of injury. Analysis at 1 week indicated that administration at both time points significantly protected against hippocampal and cortical volume loss. Analysis of parallel groups for behavioral and learning changes at 2 months postischemia demonstrated that both treated groups performed significantly better than the controls in Morris water maze functional tests. Subsequent post-mortem evaluation of brain damage at the 2-month time point confirmed neuronal loss to be similar to that observed at 1 week for all groups. We have identified several neurotrophic factors in ASC-CM, particularly insulin-like growth factor-1 and brain-derived neurotrophic factor, which are important factors that could contribute to the protective effects of ASCs observed in studies with both in vitro and in vivo neuronal injury models. These data suggest that delivery of the milieu of factors secreted by ASCs may be a viable therapeutic option for treatment of HI, as well as other brain injuries.

Effect of continuous morphine infusion on hypoxic-ischaemic brain damage of neonatal rats

Opioids are commonly administered to critically ill neonates and infants for general anaesthesia and sedation. However, the clinical safety of these drugs, especially the effects on hypoxic-ischaemic damage of the developing brain, has not been well investigated. The present study was therefore conducted to investigate the effects of continuous morphine infusion on brain damage after hypoxic-ischaemic insults in neonatal rats. Seven-day-old Sprague-Dawley rats were subjected to left common carotid artery ligation followed by a 90-min exposure of 8% oxygen. The rats were administered morphine (0.1, 0.3 or 1 mg/kg/h) or saline continuously for 72 h using osmotic minipumps. Seven days later, the rats were weighed and their brains were morphologically categorized into groups based on the following grades: 0=normal, 1=mild atrophy, 2=moderate atrophy, 3=atrophy with cystic cavitation <3 mm and 4=cystic cavitation >3 mm. For histological assessment, the ratio of the surviving neurons (ipsilateral/contralateral) was calculated in the cornu ammonis fields, CA1 and CA3, and the dentate gyrus (DG). One week after recovery (P14), the rats in the 1 mg/kg/h group showed significantly poorer weight gain compared with the other groups. However, the morphological score of the brains and the ratio of the surviving neurons in the CA1, CA3 and DG were similar among the groups. Our results indicate that continuous administration of morphine does not worsen brain damage 7 days after hypoxic-ischaemic insults in neonatal rats.

Neuroprotection of lamotrigine on hypoxic-ischemic brain damage in neonatal rats: Relations to administration time and doses

Lamotrigine (LTG), an antiepileptic drug, has been shown to be able to improve cerebral ischemic damage by limiting the presynaptic release of glutamate. The present study investigated further the neuroprotective effect of LTG on hypoxic-ischemic brain damage (HIBD) in neonatal rats and its relations to administration time and doses. The HIBD model was produced in 7-days old SD rats by left common carotid artery ligation followed by 2 h hypoxic exposure (8% oxygen). LTG was administered intraperitoneally with the doses of 5, 10, 20, and 40 mg/kg 3 h after operation and the dose of 20 mg/kg 1 h before and 3 h, 6 h after operation. Blood and brain were sampled 24 h after operation. Nissl staining, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL), and neuron-specific enolase (NSE) immunohistochemical staining were used for morphological studies. Water content in left cortex and NSE concentration in serum were determined. LTG significantly reduced water content in the cerebral cortex, as well as the number of TUNEL staining neurons in the dentate gyrus and cortex in hypoxic-ischemia (HI) model. Furthermore, LTG significantly decreased the NSE level in serum and increased the number of NSE staining neurons in the cortex. These effects, except that on water content, were dose-dependent and were more remarkable in the pre-treated group than in the post-treated groups. These results demonstrate that LTG may have a neuroprotective effect on acute HIBD in neonates. The effect is more prominent when administrated with higher doses and before HI.

Antisense in vivo knockdown of synaptotagmin I by HVJ–liposome mediated gene transfer attenuates ischemic brain damage in neonatal rats

Synaptic release of the excitatory amino acid glutamate is considered as an important mechanism in the pathogenesis of ischemic brain damage in neonates. Synaptotagmin I is one of exocytosis-related proteins at nerve terminals and considered to accelerate the exocytosis of synaptic vesicles by promoting fusion between the vesicles and plasma membrane. To test the possibility that antisense in vivo knockdown of synaptotagmin I modulates the exocytotic release of glutamate, thus suppressing the excitotoxic intracellular processes leading to neuronal death following ischemia in the neonatal brain, we injected antisense oligodeoxynucleotides (ODNs) targeting synaptotagmin I (0.3 (AS), 0.15 (0.5 AS), or 0.03 μg (0.1 AS), or vehicle) into the lateral ventricles of 7-day-old rats by using a hemagglutinating virus of Japan (HVJ)–liposome mediated gene transfer technique. At 10 days of age, these rats were subjected to an electrical coagulation of the right external and internal carotid arteries, then the insertion of a solid nylon thread into the right common carotid artery toward the ascending aorta up to 10–12 mm from the upper edge of the sternocleidomastoid muscle. Cerebral ischemia was induced by clamping the left external and internal carotid arteries with a clip, and ended by removing the clip 2 h later. Twenty-four hours after the end of ischemia, the extent of ischemic brain damage was neuropathologically and quantitatively evaluated in the neocortex and striatum. While the relative volume of damage in the cerebral cortex and striatum of the vehicle group was extended to 40% and 13.7%, respectively, that in the AS group was significantly reduced to 4.8% and 0.6%. In the 0.5 AS group, the relative volume of ischemic damage in the cerebral cortex and striatum was reduced to 20.5% and 15.4%, respectively, and the difference between the 0.5 AS group and vehicle group was statistically significant in the neocortex, but not in the striatum. These results indicated that antisense in vivo knockdown of synaptotagmin I successfully attenuated ischemic brain damage in neonatal rats and that the effect was dose-dependent. It was also suggested that this treatment was more effective in the neocortex than in the striatum in neonatal rats.

RETRACTED: Effect of ephedrine on neuronal plasticity of hypoxic-ischemic brain damage in neonatal rats

Study the effect of ephedrine on neural plasticity of hypoxic ischemic brain damaged (HIBD) in neonatal rats, and explore the underlying molecular mechanism. 60 Sprats suffered from HIBD (7 days old) were randomly divided into ephedrine group, D-amphetamine (D-AMPH) group, cytidine triphosphate (CTP) group, ganglioside (GM1) group, and spontaneous recovery group. Using immunohistochemical method to test the expression of growth-associated protein-43(GAP-43) and synaptophysin (SYP) on one side of hippocampal CA3 area, then, 4 weeks later, Morris Water Maze test was performed for five days. (1) The expression levels of GAP-43 and SYP on hippocampal CA3 area in ephedrine group were higher than that in spontaneous recovery group (P<0.05). However, there was no statistical difference in ephedrine groups, CTP group, and D-AMPH group. (2) The average time of escape latency was significantly shorter in treating groups than that in spontaneous recovery group (P<0.05), and the frequency of original platform passing was higher than that in spontaneous recovery group (P<0.01). The average time of escape latency was longer in ephedrine group than that in GM1 group. The frequency of original platform passing was significantly less in ephedrine group than that in GM1 group, No statistical difference found in ephedrine groups, CTP group, and D-AMPH group. Ephedrine may enhance memory, the abilities of spatial orientation and learning in HIBD rats. This protective effect may be associated with increasing synaptic connectivity, as assessed by increased expression of GAP-43 and SYP after HIBD. Ephedrine triggered similar protection against HIBD as treatment of D-AMPH and CTP. However, the amelioration of ability of spatial orientation, learning and memory by ephedrine on HIBD rats in later stage is slightly weaker than that by GM1, which may be related with ephedrine dosage.

Neuroprotective effects of resveratrol via anti-apoptosis on hypoxic-ischemic brain injury in neonatal rats

Purpose : Resveratrol, extracted from red wine and grapes, has an anti-cancer effect, an antiinflammatory effect, and an antioxidative effect mainly in heart disease and also has neuroprotective effects in the adult animal model. No studies for neuroprotective effects during the neonatal periods have been reported. Therefore, we studied the neuroprotective effect of resveratrol on hypoxic-ischemic brain damage in neonatal rats via anti-apoptosis. Methods : Embryonic cortical neuronal cell culture of rat brain was performed using pregnant Sprague-Dawley (SD) rats at 18 days of gestation (E18) for the in vitro approach. We injured the cells with hypoxia and administered resveratrol (1, 10, and 30 µg/mL) to the cells at 30 minutes before hypoxic insults. In addition, unilateral carotid artery ligation with hypoxia was induced in 7-day-old neonatal rats for the in vivo approach. We injected resveratrol (30 mg/kg) intraperitoneally into animal models. Real-time PCR and Western blotting were performed to identify the neuroprotective effects of resveratrol through anti-apoptosis. Results : In the in vitro approach of hypoxia, the expression of Bax, caspase-3, and the ratio of Bax/Bcl-2, indicators of the level of apoptosis, were significantly increased in the hypoxia group compared to the normoxia group. In the case of the resveratrol-treated group, expression was significantly decreased compared to the hypoxia group. And the results in the in vivo approach were the same as in the in vitro approach. Conclusion : The present study demonstrates that resveratrol plays neuroprotective role in hypoxic-ischemic brain damage during neonatal periods through the mechanism of anti-apoptosis.

Neuroprotective effects of melatonin against hypoxic-ischemic brain damage in neonatal rats

Neuroprotective effects of melatonin against hypoxic-ischemic brain damage in neonatal rats

Gender-Specific Neuroprotection by 2-Iminobiotin after Hypoxia—Ischemia in the Neonatal Rat via a Nitric Oxide Independent Pathway

We have shown earlier that 2-iminobiotin (2-IB) reduces hypoxia-ischemia (HI)-induced brain damage in neonatal rats, and presumed that inhibition of nitric oxide synthases (NOS) was the underlying mechanism. We now investigated the effect of 2-IB treatment in P7 rat pups to determine the role of gender and the neuroprotective mechanism. Pups were subjected to HI (occlusion of right carotid artery and 120 mins FiO(2) 0.08) and received subcutaneous (s.c.) 10 mg/kg 2-IB at 0, 12 and 24 h after hypoxia. After 6 weeks, neuronal damage was assessed histologically. We determined cerebral nitrite and nitrate (NO(x)) and nitrotyrosine, heat-shock protein 70, cytosolic cytochrome c, cleaved caspase 3, nuclear translocation of apoptosis-inducing factor (AIF) and the effect of 2-IB on NOS activity in cultured cells. 2-Iminobiotin treatment reduced long-term brain damage in female but not male rats. Unexpectedly, 2-IB treatment did not reduce cerebral NO(x) or nitrotyrosine levels, and did not inhibit NOS activity in vitro. The gender-dependent neuroprotective effect of 2-IB was reflected in inhibition of the HI-induced increase in cytosolic cytochrome c and cleaved caspase 3 in females only. Hypoxia-ischemia-induced activation of AIF was observed in males only and was not affected by 2-IB. Post-HI treatment with 2-IB provides gender-specific long- and short-term neuroprotection in female P7 rats via inhibition of the cytochrome c-caspase 3 neuronal death pathway. 2-Iminobiotin did not alter cerebral NO(x) nor inhibited NOS in intact cells. Therefore, we conclude that it is highly unlikely that the neuroprotective effect of 2-IB involves NOS inhibition.

Brain damage in neonatal rats following kaolin induction of hydrocephalus

Neonatal and congenital hydrocephalus are common problems in humans. Hydrocephalus was induced in 1-day-old rats by injection of kaolin into the cisterna magna. At 7 and 21 days, magnetic resonance (MR) imaging was used to assess ventricle size, then brains were subjected to histopathological and biochemical analyses. Hydrocephalic pups did not exhibit delays in righting or negative geotaxis reflexes during the first week. At 7 days, there was variable ventricular enlargement with periventricular white matter edema, axon damage, reactive astrogliosis, and accumulation of macrophages in severe but not mild hydrocephalus. Cellular proliferation in the subependymal zone was significantly reduced. The cortical subplate neuron layer was disrupted. In rats allowed to survive to 21 days, weight was significantly lower in severely hydrocephalic rats. They also exhibited impaired memory in the Morris water maze test. Despite abnormal posture, there was minimal quantitative impairment of walking ability on a rotating cylinder. At 21 days, histological studies showed reduced corpus callosum thickness, fewer mature oligodendrocytes, damaged axons, and astroglial/microglial reaction. Reduced myelin basic protein, increased glial fibrillary acidic protein, and stable synaptophysin content were demonstrated by immunochemical methods. In conclusion, impairment in cognition and motor skills corresponds to ventricular enlargement and white matter destruction. Quantitative measures of weight, memory, ventricle size, and myelin, and glial proteins in this neonatal model of hydrocephalus will be useful tools for assessment of experimental therapeutic interventions.

Selective Inhibition of Nuclear Factor-κB Activation After Hypoxia/Ischemia in Neonatal Rats Is Not Neuroprotective

Activated nuclear factor-kappaB (NFkappaB) has been shown to increase transcription of several genes that could potentially contribute to neuronal damage, such as proinflammatory cytokines, chemokines, and inducible nitric oxide synthase. The aim of our study was to investigate whether inhibition of NFkappaB activation could prevent hypoxia/ischemia (HI)-induced cerebral damage in neonatal rats. We used a cell permeable peptide (NEMO binding domain [NBD] peptide) that is known to prevent the association of the regulatory protein NEMO with IKK, the kinase that activates NFkappaB. Via this mechanism, the NBD peptide can specifically block the activation of NFkappaB, without inhibiting basal NFkappaB activity. Cerebral HI was induced in neonatal rats by occlusion of the right carotid artery followed by 90 min of hypoxia (Fio(2) = 0.08). Immediately upon reoxygenation, as well as 6 and 12 h later, rats were treated with vehicle or NBD peptide (20 mg/kg i.p.). Histologic analysis of brain damage was performed at 6 wk after HI. To assess NFkappaB activation, electromobility shift assays (EMSAs) were performed on brain nuclear extracts obtained 6 h after reoxygenation. Increased NFkappaB activity could be shown at 6 h after HI in both hemispheres. Peripheral administration of NBD peptide prevented this HI-induced increase in NFkappaB activity in both hemispheres. Histologic analysis of long-term cerebral damage revealed that inhibition of NFkappaB activation by administration of NBD peptide at 0, 6, and 12 h after HI resulted in an increment of neuronal damage. In conclusion, our data suggest that inhibition of NFkappaB activation using NBD peptide early after HI increases brain damage in neonatal rats.

A free radical scavenger, edaravone, inhibits lipid peroxidation and the production of nitric oxide in hypoxic-ischemic brain damage of neonatal rats

The purpose of this study was to elucidate a role for edaravone, a free radical scavenger 3-methyl-1-phenyl-2-pyrazolin-5-one, in neonatal hypoxic-ischemic brain damage. We determined the level of thiobarbituric acid reactive substances as an index of lipid peroxidation and nitric oxide metabolites as nitric oxide production. Seven-day-old Wistar rats were subjected to left common carotid artery ligation followed by 2 hours of 8% oxygen exposure. Then, the rats were administered edaravone (9 mg/kg) or saline solution intraperitoneally. Cerebrospinal fluid was withdrawn just before the rats were killed at 2, 5, 24, and 48 hours after hypoxia, and brains were removed. The thiobarbituric acid reactive substances and nitric oxide metabolites levels were measured in the brain tissue and cerebrospinal fluid, respectively. On the ligated side, edaravone significantly decreased thiobarbituric acid reactive substances levels at 5 and 24 hours after hypoxia, compared with saline group (P < .01). Edaravone significantly decreased the nitric oxide metabolites level in the cerebrospinal fluid only at 5 hours, compared with saline group (P < .01). Edaravone potently and transiently inhibited lipid peroxidation and the production of nitric oxide in the neonatal rat brain after hypoxic-ischemic insult.

Expression of inducible nitric oxide synthase and cyclooxygenase‐2 mRNA in brain damage induced by lipopolysaccharide and intermittent hypoxia–ischemia in neonatal rats

The purpose of the present study was to examine the effect of lipopolysaccharide (LPS) and intermittent hypoxia-ischemia (HI) on brain damage in neonatal rats. Seven-day-old Wistar rats were injected with saline or LPS (1 mg/kg), and then underwent left common carotid artery ligation followed by a repetitive 8% hypoxia (2.0-4.5 min) at 10-min intervals 10 times. The rats were divided into three groups: LPS with HI (LPS/HI, n = 46), saline with HI (HI alone, n = 42) and LPS alone (n = 16). Seven days later, brains were assessed for neuronal damage and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA expression. Neuronal damage in the ligated side was significantly higher in LPS/HI than the other two groups (P < 0.01). The expression of iNOS and COX-2 mRNA was observed in the affected brain in LPS/HI, which corresponded well to histologic neuronal loss. LPS enhanced intermittent HI brain damage in immature animals. The expression of iNOS and COX-2 mRNA is considered to be associated with perinatal brain injury processes.

Dexamethasone Downregulates Chemokine Receptor CXCR4 and Exerts Neuroprotection against Hypoxia/Ischemia-Induced Brain Injury in Neonatal Rats

Objective: Hypoxia/ischemia (H/I) induces rapid and massive brain damage in neonatal rat brain, resulting in long-term consequences on structural and functional maturation of the central nervous system. Inflammatory mediators contribute to these permanent pathological changes, which are sensitive to corticoid treatments. Since the chemokine receptor CXCR4, specific for the SDF-1α/CXCL12 ligand, regulates both apoptotic and neuroregeneration processes, this receptor was quantified 2 days following H/I in neonatal rat brain in relation with dexamethasone (DEX) treatment. Methods: Seven-day-old male rats were exposed to a 90-min hypoxia following unilateral carotid ligation (H/I) and were sacrificed 48 h later. Glucocorticoid-pretreated animals were injected subcutaneously 5 h prior to hypoxia with 0.5 µg/g DEX. Glial fibrillary acidic protein and cresyl violet staining were used for assessing the extent of brain lesion subdivided into necrotic and penumbra-like areas. The density of CXCR4 receptors was determined by quantitative autoradiography using [¹²⁵I]SDF-1α as a ligand. Results: The H/I resulted in a massive lesion ipsilateral to the carotid ligation, which was extended to cortical, striatal, hippocampal and thalamic areas, while the contralateral hemisphere remained apparently unaffected. DEX decreased the lesion size by reducing mainly the necrotic area. H/I induced a marked increase in CXCR4 receptor binding in the penumbra-like areas. DEX pretreatment decreased CXCR4 receptor density in the penumbra and attenuated astrocytosis. Furthermore, DEX strongly lowered mortality rate and reduced functional recovery time right after hypoxia. Conclusion: The rapid enhancement in CXCR4 chemokine receptor binding in the affected brain areas suggests that SDF-1α/CXCR4 may play a role in the hypoxia-induced inflammatory reaction in the neonatal brain. Attenuation of CXCR4 expression and astrogliosis could contribute to the neuroprotective effect of DEX pretreatment via influencing the inflammatory cascade induced by H/I in the neonatal brain.

The protective mechanism of insulin-like growth factor-1 from hypoxic-ischemic brain damage in neonatal rats

目的 建立单侧缺氧缺血性脑损伤(HIBD)动物模型,研究胰岛素样生长因子1(IGF 1)对HIBD的影响和可能机制. 方法选择健康7日龄Wistar大鼠120只,建立HIBD模型,随机分成假手术组、HIBD组、HIBD后0.2 mg/kg人基因重组IGF-1干预组(RH-IGF-1组)、0.066mg/kg人基因重组IGF-1干预组(SRH-IGF-1组)及盐水对照组(对照组).各组按观察时段进一步分为24、48、72 h组,每组8只.各组于规定时刻观测脑形态学改变、谷氨酸(Glu)含量、凋亡细胞计数、Bcl-2蛋白表达. 结果(1)HIBD 48 h组Glu(1162.2±108.1)mg/kg,较假手术组(750.9±53.4)mg/kg明显升高(P＜0.05);HIBD组凋亡细胞计数[24 h:(7.6±1.9)%,48 h(12.6±1.2)%,72 h:(1 3.8±0.9)%],较假手术组[24 h(2.0±0.2)%,48 h(2.0±0.3)%,72 h(2.0±0.2)%]明显增加(P均＜0.05).(2)与对照组相比,RH-IGF-1组脑组织病变减轻;干预48 h组Glu[SRH-IGF-1组(781.4±54.2)mg/kg,RH-IGF-1组(740.5±46.6)mg/kg],较对照组(1126.6±48.0)mg/kg明显降低(P均＜0.05);RH-IGF-1组凋亡细胞计数[24 h:(3.6±0.9)%,48 h(8.2±2.2)%,72 h(9.4±1.4)%],较对照组[24 h(7.6±1.9)%,48 h(12.6±1.6)%,72 h(13.9±0.4)%]明显降低(P均＜0.05),RH IGF-1 48 h、72 h组Bcl-2蛋白表达阳性率分别为71.4%,71.4%,较对照组14.2%,14.2%明显升高(P均＜0.05). 结论(1)IGF 1可明显降低损伤脑中Glu含量,阻断Glu的脑损伤途径.(2)IGF-1通过降低细胞凋亡、提高保护性Bcl-2蛋白表达以避免和改善HIBD,并呈剂量依赖效应。

Lipopolysaccharide administration enhances hypoxic-ischemic brain damage in newborn rats.

To determine whether inflammation and hypoxic-ischemic insult (HI) act additively to cause brain damage in perinatal animals by examining the dose-response effect of lipopolysaccharide (LPS) administration on HI insult in neonatal rat pups. Seven-day-old Wistar rats (n = 119) were divided into three groups: (i) a group that received a pre-injection of LPS and HI (LPS/HI, 1 mg/kg, n = 31; 0.5 mg/kg, n = 20; 0.1 mg/kg, n = 17); (ii) a group that received a pre-injection of saline and HI (saline/HI, n = 35); and (iii) those that received LPS alone (1 mg/kg, n = 16). At 4 h after the injection, rat pups from groups (i) and (11) were exposed to unilateral carotid artery ligation, followed by 1 h of hypoxia (8% oxygen in 92% nitrogen) at 33 degrees C. Seven days after the insult, they were sacrificed and their brains removed for histological study. Neuronal damage was categorized as mild, < or =25%; moderate, 25-50%; and severe, > or =50% of surface area on a single section. Mortality rate during the experiment was significantly increased in the 1 mg/kg of LPS/HI group (12 of 31, 39%) compared with the saline/HI group (0%). No neuronal damage was observed in the LPS only group. However, when LPS was added to HI, neuronal loss in the cerebral cortex and hippocampus was significantly increased in a dose-response manner. LPS potentiates hypoxic-ischemic insult in a dose-dependent fashion to cause brain damage in neonatal rats.