Hypoxic preconditioning can reduce injury-induced inflammatory processes in the neonatal rat brain

Inflammation plays an important role in the pathophysiology of neonatal hypoxic–ischemic (HI) brain injury. Studies have shown that hypoxic preconditioning (HP) can ameliorate brain damage, but its effects on inflammation remain unknown. Postnatal day 6 (P6), Sprague–Dawley rats were divided into normoxia and hypoxia (8% oxygen, 3 h) groups. On P7, some pups underwent a right carotid artery occlusion followed by hypoxia (8% oxygen, 3 h) while under 1.5% isofluorane anesthesia and the remaining pups underwent sham surgery without occlusion. Animals were sacrificed 5 days later and fixed tissue was used to examine changes in neurons, astrocytes, and microglia in the cortex. Fresh tissue was collected to determine cortical levels of proinflammatory cytokines using ELISA. There was a significant loss in the number of NeuN positive cells in the cortex following HI injury, which was improved when HP was given prior to HI. There was an increase in cortical area of astrocyte staining after HI injury compared to control. HP before HI was able to reduce area of GFAP staining back to control levels. HI caused a large increase in the number of activated microglia compared to control and HP was able to significantly reduce this, although not back to control levels. HP alone increased microglial activation. Interleukin-1β levels were increased in the cortex 5 days after HI, but HP was not able to significantly reduce this change. The neuroprotective effects of HP appear to be mediated by affecting cellular inflammatory processes in the brain following HI injury.     

Early biochemical effects after unilateral hypoxia–ischemia in the immature rat brain

Perinatal hypoxia–ischemia (HI) gives rise to inadequate substrate supply to the brain tissue, resulting in damage to neural cells. Previous studies at different time points of development, and with different animal species, suggest that the HI insult causes oxidative damage and changes Na⁺, K⁺–ATPase activity, which is known to be very susceptible to free radical-related lipid peroxidation. The aim of the present study was to establish the onset of the oxidative damage response in neonatal Wistar rats subjected to brain HI, evaluating parameters of oxidative stress, namely nitric oxide production, lipoperoxidation by thiobarbituric acid reactive substances (TBA-RS) production and malondialdehyde (MDA) levels, reactive species production by DCFH oxidation, antioxidant enzymatic activities of catalase, glutathione peroxidase, superoxide dismutase as well as Na⁺, K⁺–ATPase activity in hippocampus and cerebral cortex. Rat pups were subjected to right common carotid ligation followed by exposure to a hypoxic atmosphere (8% oxygen and 92% nitrogen) for 90 min. Animals were sacrificed by decapitation 0, 1 and 2 h after HI and both hippocampus and cerebral cortex from the right hemisphere (ipsilateral to the carotid occlusion) were dissected out for further experimentation. Results show an early decrease of Na⁺, K⁺–ATPase activity (at 0 and 1 h), as well as a late increase in MDA levels (2 h) and superoxide dismutase activity (1 and 2 h after HI) in the hippocampus. There was a late increase in both MDA levels and DCFH oxidation (1 and 2 h) and an increase in superoxide dismutase activity (2 h after HI) in cortex; however Na⁺, K⁺–ATPase activity remained unchanged. We suggest that neonatal HI induces oxidative damage to both hippocampus and cortex, in addition to a decrease in Na⁺, K⁺–ATPase activity in hippocampus early after the insult. These events might contribute to the later morphological damage in the brain and indicate that it would be essential to pursue neuroprotective strategies, aimed to counteract oxidative stress, as early as possible after the HI insult.     

The effects of hypoxic preconditioning on white matter damage following hypoxic-ischaemic injury in the neonatal rat brain

Myelination is an essential process in human development that is carried out by oligodendrocytes in the central nervous system. Hypoxic-ischaemic (HI) brain injury can disrupt myelination by causing oxidative stress, inflammation and excitotoxicity, resulting in the loss of myelin as well as cells of the oligodendrocyte lineage. We have previously shown that hypoxic preconditioning (HP) can protect against HI injury, however, to date there have been no reports of its effects on white matter injury. Sprague-Dawley rat pups (postnatal day (P) 6) were placed into control and HP groups. On P7, pups were further separated into HI and sham surgery groups. HI pups underwent a unilateral common carotid artery occlusion and then exposed to 8% oxygen for 3 h. Sham pups underwent the same procedure without occlusion and were maintained in room air. Brains were removed 5 days post-surgery for analysis. In HI-only pups there was a significant reduction in brain volume observed. Consequently, when HP was performed prior to HI, the loss of brain tissue was prevented. The number of early and late oligodendrocyte progenitors (preOLs) in the corpus callosum was unaffected by HI, however, HI reduced the amount of myelin basic protein, indicating that HI may inhibit the maturation of preOLs. Whilst HP did not affect preOL density, it was found to prevent the loss of myelin caused by HI. This indicates that HP may either protect myelin directly or possibly promote the maturation of preOLs to regenerate the lost or damaged myelin.     

Effect of lithium-pilocarpine-induced status epilepticus on ultrasonic vocalizations in the infant rat pup

Evidence shows that febrile convulsions induced in rat pups increase ultrasonic vocalizations (USVs); however, the effect of status epilepticus (SE) induced in developing rats on USVs has not been fully investigated. The goal of this study was to analyze USVs following lithium-pilocarpine-induced SE in fourteen-day-old (P14) rat pups. The rat pups were given 3-mEq/kg lithium chloride i.p. on the day before the induction of SE, which was carried out at P14 by subcutaneous injection of 100-mg/kg pilocarpine hydrochloride; control animals were given an equal volume of lithium chloride and saline on P13 and P14, respectively. Ultrasonic vocalizations were monitored at P15, P16, and P21 with a Mini 3 Bat Detector Ultra Sound Advice (15 kHz–160 kHz) set at 40 ± 4 kHz and digitally recorded in WAV format using the Audacity 1.3 beta software. A clear box (60 × 40 × 30 cm) split down the middle with a holed wall was used; each pup was placed alone in one compartment, whereas its dam was placed on the other cage side at room temperature. Vocalizations were recorded over a 5-minute period, converted to sonograms and spectrograms, and analyzed using the Raven software. Parameters evaluated were as follows: USV frequency, latency to the first USV, and mean USV duration. There was a significant decrease in the latency (35.5 ± 6.9 s) and duration (50.8 ± 8.6 s) of USVs after SE compared with the control group (81.9 ± 10.8 s and 78.1 ± 9.9 s, respectively). Status epilepticus affected male and female rats differentially.     

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% O₂ 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.     

Maternal administration of magnesium sulfate promotes cell proliferation in hippocampus dentate gyrus in offspring mice after exposing to prenatal stress

Prenatal stress (PS) inhibits cell proliferation in the hippocampal dentate gyrus (DG), which is related to hippocampal anatomy and function abnormality. The aim of the study was to investigate the effects of magnesium sulfate (MgSO₄) on PS-induced cell proliferation suppression in offspring during embryonic stage and postnatal spatial learning. MgSO₄ administration was performed after PS treatment on pregnant mice. Mice were randomly divided into four groups: non-PS or PS maternal mice injected with MgSO₄ or saline (P + NS, P + MG, C + MG and C + NS group). Corticosterone was collected from amniotic fluid of mother mice on day 17 of embryonic stage (E17). The ability for spatial learning and memory of pups postnatal 3 week was evaluated using water maze assay. Additionally, cell proliferation was detected by assessing the expression of Ki67 using immunohistochemistry in mice fetuses or pups. PS significantly increased corticosterone level in amniotic fluid (P < 0.05) and impaired the spatial learning and memory (P + NS vs C + NS of latency time and track path length: P < 0.05) of offspring on postnatal day 21. However, MgSO₄ administration could reverse PS-induced spatial learning and memory disability (P + MG vs P + NS, P < 0.05). Additionally, PS reduced the number of Ki67-positive cell in hippocampal DG on E17, E19 and postnatal day 21 (P + NS vs C + NS, P < 0.05), which were also abrogated by maternal administration of MgSO₄ (P + MG vs P + NS, P < 0.05). Collectively, prenatal administration of MgSO₄ can reverse PS-induced reduction of cell proliferation in hippocampal DG during embryonic stage and postnatal spatial learning.     

Sound exposure accelerates reflex emergence and development in young rats

Early sensory experience affects brain development. In rats, most somatic reflexes are not expressed at birth but may take as long as 2 weeks to emerge. Whether sensory enrichment during this early period affects reflex maturation remains unknown. Here, we exposed rat pups to a pure tone (4 kHz, 65 dB SPL, 8 h/day) with their nursing mother during the first 3 postnatal weeks and measured the times when reflexes appeared on the basis of video recordings. Sound exposure accelerated by about 15% the appearance of all reflexes assessed (righting, cliff avoidance, vibrissa placing, negative geotaxis and auditory startle, p < 0.001). In addition, sound exposure accelerated the appearance of developmental characteristics: incisor eruption, ear unfolding and eye opening. These changes occurred concomitantly with an increase in pups’ body and brain weights, together with a dramatic increase in fluid intake of the nursing mother. These findings are the first evidence that early sound exposure, even before opening of ear canals, accelerates reflex development. We speculate that the observed changes could involve the nursing mother.     

Effects of undernourishment,recurrent seizures and enriched environment during early life in hippocampal morphology

It has been recently shown that enriched environment led to a significant benefit in learning and retention of visual–spatial memory, being able to reverse the cognitive impairment generated by undernourishment and recurrent seizures. We investigated the hippocampal morphological effects of recurrent seizures and undernourishment early in life in Wistar rats and the possible benefits produced by the enriched environment in these conditions. The morphological parameters stereologically evaluated were hippocampal volume, thickness of pyramidal stratum of the CA1 subfield and neuronal and glial densities in the same subfield. Male Wistar rats were divided into eight groups including nourished, nourished + enriched environment, nourished + recurrent seizures, nourished + recurrent seizures + enriched environment, undernourished, undernourished + enriched environment, undernourished + recurrent seizures and undernourished + recurrent seizures + enriched environment. Undernourishment model consisted in nutritional deprivation regimen from post-natal day 2 (P2) to P15. From P8 to P10, recurrent seizures group were induced by flurothyl three times per day. Enriched environment groups were exposed between P21 and P51. Our main findings were: (1) animals submitted to the enriched environment showed an increased hippocampal volume; (2) enriched environment promotes increases in the thickness of the pyramidal layer in hippocampal CA1 subfield in animals nourished and undernourished with recurrent seizures; (3) undernourishment during early development decreased neuronal density in CA1 and CA3 subfields. Our findings show that these three conditions induces important changes in hippocampal morphology, the most deleterious changes are induced by undernourishment and recurrent seizures, while more beneficial morphological changes are produced by enriched environment.     

Variations in the neonatal environment modulate adult behavioral and brain responses to palatable food withdrawal in adult female rats

Background/objectivesEarly handling alters adult behavioral responses to palatable food and to its withdrawal following a period of chronic exposure. However, the central mechanisms involved in this phenomenon are not known. Since neonatal handling has persistent effects on stress and anxiety responses, we hypothesized that its involvement in the aforementioned association may be associated with differential neuroadaptations in the amygdala during withdrawal periods.MethodsLitters were randomized into two groups: handled (H, removed from their dam for 10 min per day from the first to the tenth postnatal day and placed in an incubator at 32 °C) and non-handled (NH). Experiment 1: on PNDs 80–100, females were assigned to receive palatable food + rat chow for 15 or 30 days, and these two groups were compared in terms of palatable food preference, body weight and abdominal fat deposition. In Experiment 2, H and NH rats were exposed to a chronic diet of palatable food + rat chow for 15 days, followed by (a) no withdrawal, (b) 24 h withdrawal from palatable food (receiving only rat chow) or (c) 7-day withdrawal from palatable food (receiving only rat chow). Body weight, 10-min rebound palatable food intake, abdominal fat deposition, serum corticosterone as well as TH and pCREB levels in the amygdala were then compared between groups.ResultsExperiment 1—chronic exposure to palatable food induces comparable metabolic effects after 15 and 30 days. Experiment 2—neonatal handling is associated with a peculiar response to palatable food withdrawal following chronic exposure for 15 days. Rats exposed to early handling ingested less of this food after a 24 h withdrawal period, and displayed increased amygdala TH and pCREB levels.ConclusionsVariations in the neonatal environment affect both behavioral responses and amygdala neuroadaptation to acute withdrawal from a palatable diet. These findings contribute to the comprehension of the mechanisms that link early life events and altered feeding behavior and related morbidities such as obesity in adulthood.     

Protective action of tetramethylpyrazine on the medulla oblongata in rats with chronic hypoxia

Tetramethylpyrazine (TMP), one of the active ingredients of the Chinese herb Lingusticum Wallichii Frantchat (Chuan Xiong), plays an important role in neuroprotection. However, the protective effect of TMP on the medulla oblongata, the most important region of the brain for cardiovascular and respiratory control, during chronic hypoxia remains unclear. In this study, we examined the neuroprotective effect of TMP on the medulla oblongata after chronic hypoxic injury in rats. Male Sprague–Dawley rats were randomly divided into four groups: control group, TMP group, chronic hypoxia group, and chronic hypoxia + TMP group. Rats were exposed to hypoxia (10% (v/v) O₂) or normoxia for 6 h daily for 14 days. TMP (80 mg/kg) or vehicle (saline) was injected intraperitoneally 30 min before experimentation. Loss of neurons in the pre-Bötzinger complex, the nucleus ambiguus, the nucleus tractus solitarius, the hypoglossal nucleus and the facial nucleus were evaluated by Nissl staining. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured, and apoptosis was monitored using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. The level of Bcl-2 mRNA and Bax mRNA was quantitatively measured by RT-PCR analysis. TMP protected Nissl bodies of neurons from injury in all nuclei observed, and reduced the loss of neurons in the nucleus ambiguus, the nucleus tractus solitarius, and the hypoglossal nucleus in rats subjected to chronic hypoxia. TMP upregulated SOD activity and inhibited the increase in MDA content in the medulla oblongata of hypoxic rats. In addition, TMP decreased the rate of apoptosis index (the percentage of apoptotic cells against the total number of cells) in all medullary structures examined, excepting the nucleus ambiguus and inhibited the decrease in Bcl-2 mRNA levels in the medulla oblongata following hypoxia. Our findings indicate that TMP may protect the medullary structures that are involved in cardiovascular and respiratory control from injury induced by chronic hypoxia in rats via its anti-oxidant and anti-apoptotic effects.     

Early postnatal exposure to methylphenidate alters stress reactivity and increases hippocampal ectopic granule cells in adult rats

To mimic clinical treatment with methylphenidate (MPH; Ritalin) for attention deficit/hyperactivity disorder (ADHD), rat pups were injected with MPH (5 mg/kg, I.P.) or placebo twice daily during their nocturnal active phase from postnatal day (PND) 7–35. Thirty-nine days after the last MPH administration (PND 76), four litters of rats experienced stressful conditions during the 2003 New York City blackout. MPH-treated rats that endured the blackout lost more weight and regained it at a slower pace than controls (p < 0.05; N = 7–11 per group). Furthermore, MPH-treated rats had elevated systolic arterial blood pressure (from 115.6 ± 1.2 to 126 ± 1.8 mmHg; p < 0.05), assessed on PND 130 by tail cuff plethysmography. Immunocytochemical studies of transmitter systems in the brain demonstrated rearrangements of catecholamine and neuropeptide Y fibers in select brain regions at PND 135, which did not differ between blackout and control groups. However, MPH-treated rats that endured the blackout had more ectopic granule cells in the hilus of the dorsal hippocampal dentate gyrus compared to controls at PND 135 (p < 0.05; N = 6 per group). These findings indicate that early postnatal exposure to high therapeutic doses of MPH can have long lasting effects on the plasticity of select brain regions and can induce changes in the reactivity to stress that persist into adulthood.     

Tumor necrosis factor-α impairs the recovery of synaptic transmission from hypoxia in rat hippocampal slices

Cerebral ischaemia is a common occurrence in a range of pathological conditions, including stroke and traumatic brain injury. Two of the components in ischaemia are tissue hypoxia and the release of pro-inflammatory agents such as TNF-α. The role of TNF-α in an ischaemic/hypoxic episode is still controversial, although deleterious effects of pro-inflammatory cytokines in the area of injury are well documented. One of the prime adaptive mechanisms in response to hypoxia is the cellular activation of adenosine 1 receptors (A1Rs), which inhibits excitatory synaptic transmission. In the present study we have examined the effect of TNF-α application on synaptic transmission during hypoxic exposure and re-oxygenation using extracellular recordings in the CA1 region of the rat hippocampal slice. Hypoxia caused a reversible depression of the field EPSP (29.6 ± 9.7% of control, n = 5), which was adenosine A₁ receptor-dependent (85.7 ± 4.3%, in the presence of DPCPX (200 nM), the adenosine A₁ receptor antagonist). DPCPX inhibited the maintenance of long-term potentiation obtained 30 min post hypoxia (143.8 ± 8.2% versus 96.4 ± 10.6% respectively, 1 h post tetanus; n = 5; p < 0.005). In TNF-α (150 pM) treated slices hypoxic depression was similar to controls but a reduction in fEPSP slope was observed during re-oxygenation (66.8 ± 1.4%, n = 5). This effect was reversed by pre-treatment with SB 203580 (1 µM), a p38 MAP kinase inhibitor (91.8 ± 6.9%, n = 5). These results demonstrate a novel p38 MAPK dependent role for TNF-α in attenuating synaptic transmission after a hypoxic episode.     

Association between FSP,CVHI, inflammatory cytokines and the incidence of primary stroke

This case-control study was designed to establish a new risk-prediction model for primary stroke using Framingham stroke profile (FSP), cerebral vascular hemodynamic indexes (CVHI) and plasma inflammatory cytokines including hs-CRP, IL-6, TNF-α and Lp-PLA2. A total of 101 primary stroke patients admitted to Dongguan Houjie Hospital between August 2014 and June 2015 were assigned into the case group, and 156 age- and gender-matched healthy subjects from the Houjie Community were allocated into the control group. The prognostic values of FSP, CVHI and inflammatory cytokines including high sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and lipoprotein-associated phospholipase A2 (Lp-PLA2) were assessed by multivariate logistic regression analysis. Seven risk-prediction models (FSP, CVHI, inflammatory cytokine, FSP + CVHI, FSP + inflammatory cytokine, CVHI + inflammatory cytokine, CVHI + FSP + inflammatory cytokine) were successfully established and the prognostic values were statistically compared by ROC curve and Z test. For FSP, the stroke risk was significantly elevated by 2.85 times when the FSP score was increased by 1 level (P = 0.043), increased by 3.25 times for CVHI (P = 0.036), 6.53 times for IL-6 (P = 0.003), and 7.75 times for Lp-PLA2 (P = 0.000). The sensitivity of FSP + CVHI + inflammatory cytokine and CVHI + inflammatory cytokine models was higher than 90%. For model specificity, the specificity of FSP + CVHI + inflammatory cytokine model alone exceeded 90%. FSP, CVHI, IL-6 and Lp-PLA2 are independent risk factors of stroke. Integrating IL-6 and Lp-PLA2 into the models can significantly enhance the risk prediction accuracy of primary stroke. Combined application of FSP + CVHI + inflammatory cytokine is of potential for risk prediction of primary stroke.     

Paraoxonase 1 and cytochrome P450 polymorphisms in susceptibility to acute organophosphorus poisoning in Egyptians

BackgroundOrganophosphates are the basis of many insecticides, herbicides, and nerve agents. They were listed as highly acutely toxic agents. Findings in knockout mice suggest that paraoxonase 1 may modulate the toxicity resulting from exposure to organophosphorus compounds. In human, there is no enough data about genetic modulation of acute organophosphorus intoxication. CYP2D6 is involved in the metabolism of about 30% of xenobiotics. Prompt accurate management of OP acute intoxication can promote patient's survival.Design and methodsForty acute organophosphorus intoxicated patients were divided according to presence of clinical toxicity manifestations and serum level of pseudo-cholinesterase into two groups of acute symptomatic and acute asymptomatic patients. A third group of 29 healthy volunteers served as control. Paraoxonase 1 Q192R and CYP2D6 G1934A polymorphisms, (QQ, QR, and RR for PON1) and (GG, GA, and AA for CYP2D6), were studied using polymerase chain reaction-restriction fragment length polymorphism technique. Serum paraoxonase 1 and pseudo-cholinesterase activities were measured spectrophotometrically.ResultsSerum pseudo-cholinesterase was significantly reduced in both acute intoxication groups compared to the controls (p = 0.000). Paraoxonase 1 was significantly reduced in the symptomatic acute intoxication patients in comparison to the asymptomatic group (p = 0.002). There was a significant increase in paraoxonase 1 192 RR genotype and R allele in the symptomatic patients in comparison to the controls and asymptomatic patients (p = 0.006 and p = 0.01, respectively). For CYP2D6 G1934A genotypes and alleles, no significant difference was found between groups (p = 0.3 and p = 0.18, respectively). However, one case of the two recorded fatalities was for a symptomatic female patient with the only traced AA genotype. The combination of both single nucleotide polymorphisms revealed a significant distribution difference between groups, with QQ + GG genotypes being more represented in the controls, while RR + GA genotypes were exclusively present in the group of symptomatic patients (p = 0.04), none of the participants was found to have RR + AA genotypes.Some nicotinic (fasciculation and weakness), and muscarinic symptoms (bronchospasm, salivation, lacrimation, and diarrhea), increased with high significance in the symptomatic group compared to the asymptomatic one (p < 0.001 for all). Convulsions also showed significant increase (p = 0.02).ConclusionParaoxonase 1 Q192R modulates patient's response, and CYP2D6 may be related to the acute organophosphorus intoxication in the context of other genetic-environmental factors. Paraoxonase 1 enzyme level is related to symptom severity in acute OP poisoning, while pseudo-cholinesterase level indicates exposure to OP rather than severity of clinical manifestations.     

Changes in the NPY immunoreactivity in gerbil hippocampus after hypoxic and ischemic preconditioning

Preconditioning with sublethal ischemia or hypoxia may reduce the high susceptibility of CA1 pyramidal neurons to ischemic injury. In this study, we tested the hypothesis that enhanced level of neuropeptide Y (NPY) might play a role in the mechanisms responsible for this induced tolerance. Changes in NPY immunoreactivity in the hippocampal formation of preconditioned Mongolian gerbils were compared with the level of tolerance to test ischemia. Tolerance was induced by preconditioning with 2-min of ischemia or with three trials of mild hypobaric hypoxia (360 Torr, 2 h), separated by 24 h, that were completed 48 h before the 3-min test ischemia. The number of NPY-positive neurons in the gerbil hippocampal formation was assessed 2, 4 and 7 days after preconditioning. Survival of the CA1 pyramidal neurons was examined 14 days after the insult. Our experiments demonstrated that ischemic and hypoxic preconditioning produced equal attenuation of the damage evoked by 3-min ischemia, although the pattern of NPY immunoreactivity in the hippocampus differed. Preconditioning ischemia resulted in a 20% rise in the number of NPY-positive neurons 2 days later that disappeared 4 days after the ischemic episode, while mild hypobaric hypoxia induced a twofold increase in the number of NPY-positive neurons that lasted for at least 7 days. Although induced tolerance to ischemia 2 days after ischemic or hypoxic preconditioning was accompanied by increased immunoreactivity of NPY, there was no correlation between its intensity and the level of neuroprotection.     

Intermittent hypercapnic hypoxia effects on the nicotinic acetylcholine receptors in the developing piglet hippocampus and brainstem

This study investigated the effects of acute (1 day) vs repeated (4 days) exposure to intermittent hypercapnic hypoxia (IHH) on the immunohistochemical expression of α2, α3, α5, α7, α9 and β2 nicotinic acetylcholine receptor (nAChR) subunits in the developing piglet hippocampus and brainstem medulla, and how prior nicotine exposure alters the response to acute IHH. Five piglet groups included: 1 day IHH (1D IHH, n = 9), 4 days IHH (4D IHH, n = 8), controls exposed only to air cycles for 1 day (1D Air, n = 6) or 4 days (4D Air, n = 5), and pre-exposed to nicotine for 13 days prior to 1 day IHH (Nic + 1D IHH, n = 7). The exposure period alternated 6 min of HH (8%O₂, 7%CO₂, balance N₂) and 6 min of air over 48 min, while controls were switched from air-to-air. Results showed that: 1. repeated IHH induces more changes in nAChR subunit expression than acute IHH in both the hippocampus and brainstem medulla, 2. In the hippocampus, α2 and β2 changed the most (increased) following IHH and the CA3, CA2 and DG were mostly affected. In the brainstem medulla, α2, α5, α9 and β2 were changed (decreased) in most nuclei with the hypoglossal and nucleus of the solitary tract being mostly affected. 3. Pre-exposure to nicotine enhanced the changes in the hippocampus but dampened those in the brainstem medulla. These findings indicate that the nAChRs (predominantly with the α2/β2 complex) are affected by IHH in critical hippocampal and brainstem nuclei during early brain development, and that pre-exposure to nicotine alters the pattern of susceptibility to IHH.     

General anesthesia or conscious sedation for endovascular therapy of basilar artery occlusions: ETIS registry results

Background and purposeAcute basilar artery occlusions (BAO) are associated with poor outcome despite modern endovascular treatment (EVT). The best anesthetic management during EVT is not known and may affect the procedure and clinical outcome. We compared the efficacy and safety of general anesthesia (GA) and conscious sedation/local anesthesia (CS/LA) in a large cohort of stroke patients with BAO treated with EVT in current clinical practice.MethodsData from the ongoing prospective multicenter Endovascular Treatment In Ischemic Stroke Registry of consecutive acute BAO patients who had EVT indication from January 1st, 2015, to December 31st, 2021, were retrospectively analyzed. Two groups were compared: patients treated with CS/LA versus GA (both types of anesthesia being performed in the angiosuite). Good outcome was defined as modified Rankin Scale (mRS) score 0–3 at 90 days.ResultsAmong the 524 included patients, 266 had GA and 246 had CS/LA (67 LA). Fifty-three patients finally did not undergo EVT: 15 patients (5.9%) in the GA group and 38 patients (16.1%) in the CS/LA group (P < 0.001). After matching, two groups of 129 patients each were retained for primary analysis. The two groups were well balanced in terms of baseline characteristics. After adjustment, CS/LA compared to GA was not associated with good outcome (OR = 0.90 [95%CI 0.46–1.77] P = 0.769) or mortality (OR = 0.75 [0.37–1.49] P = 0.420) or modified thrombolysis in cerebral infarction score 2b-3 (OR = 0.43 [0.16–1.16] P = 0.098). On mixed ordinal logistic regression, the modality of anesthesia was not associated with any significant change in the overall distribution of the 90-day mRS (adjusted OR = 1.08 [0.62–1.88] P = 0.767).ConclusionsSafety, outcome and quality of EVT under either CS/LA or GA for stroke due to acute BAO appear similar. Further randomized trials are warranted.     

Hypoxia and nicotine effects on Pituitary adenylate cyclase activating polypeptide (PACAP) and its receptor 1 (PAC1) in the developing piglet brainstem

Pituitary adenylate cyclase activating polypeptide (PACAP) and its cognate receptor 1 (PAC1), have been implicated in the pathophysiology of the Sudden Infant Death Syndrome (SIDS). Two main risk factors for SIDS are prone sleeping and cigarette smoke exposure. Using piglet models of these risk factors, intermittent hypercapnic hypoxia (IHH-mimicking rebreathing in prone position) and nicotine (main reinforcing element of cigarettes), this study aimed to determine their effects on PACAP and PAC1 protein expression in the medulla. IHH was delivered for 1 (n = 7), 2 (n = 6), 3 (n = 6) and 4 (n = 7) days prior to euthanasia at 13–14 days of age, while nicotine (n = 7) was continuous for the first 14 days of life. An additional group of combined nicotine and 1 day IHH (1DIHH) was studied to determine the combined effects of the risk factors. Changes in expression were seen after the acute 1DIHH exposure (none after repeated daily exposures) and included a decrease in PACAP in the dorsal motor nucleus of vagus (DMNV; p = 0.024), nucleus of the solitary tract (NTS; p = 0.024) and the gracile nucleus (GRAC; p = 0.001), and a decrease in PAC1 in the NTS (p = 0.01). No PACAP change was noted in the nicotine-exposed piglets, however, a decrease in PAC1 was found in the DMNV (p = 0.02). IHH exposure in piglets with pre-exposure to nicotine led to a significant decrease in PACAP in the Grac (p = 0.04) but had no effect on PAC1. These findings show for the first time, the vulnerability of PACAP in the brainstem during early development to an acute hypercapnic hypoxic exposure and that those effects are greater than from nicotine exposure.     

The neuroprotective effect of diazoxide is mediated by mitochondrial ATP-dependent potassium channels in a rat model of acute subdural hematoma

Acute subdural hematoma (ASDH) results in neuronal death due to mitochondrial dysfunction and a subsequent cascade of apoptotic and necrotic events. We previously demonstrated that mitochondrial ATP-dependent potassium (mitoK_ATP) channels have a major role in cerebral ischemic preconditioning in vivo and in vitro. However, the role of the mitoK_ATP channel has not been investigated in the context of ASDH. Thus, the purpose of this study was to determine whether the mitoK_ATP channel mediates neuroprotection in a rat model of ASDH. Male Wistar rats were subjected to subdural infusion of 400 μL autologous venous blood. The rats were assigned to four experimental groups pretreated intraventricularly 15 minutes before ASDH with (1) vehicle (n = 10); (2) the mitoK_ATP channel agonist diazoxide (n = 9); (3) diazoxide plus the selective mitoK_ATP channel antagonist 5-hydroxydecanoate (5-HD) (n = 6); or (4) 5-HD alone (n = 6). Infarct volume was assessed at 4 days after ASDH. Brain edema formation was also measured. Pretreatment with diazoxide significantly reduced infarct volume and brain edema formation after ASDH. However, the effects of diazoxide were abolished by co-treatment with 5-HD. 5-HD alone increased infarct volume. These data suggest that the mitoK_ATP channel is an important mediator of the neuroprotective effects of cerebral preconditioning in a rat model of ASDH.