Erythropoietin protects newborn rat against sevoflurane-induced neurotoxicity

Neuroprotective effect of erythropoietin on anesthesia-induced neurotoxicity through the modulation of autophagy in Caenorhabditis elegans

BACKGROUND

The anti-oxidative, anti-inflammatory, and anti-apoptotic effects of erythropoietin may provide neuroprotective effects. Erythropoietin also modulates autophagy signaling that may play a role in anesthesia-induced neurotoxicity (AIN). Herein, we investigated whether AIN can be attenuated by the neuroprotective effect of erythropoietin in the Caenorhabditis elegans (C. elegans).

METHODS

Synchronized worms were divided into the control, Iso, EPO, and EPO-Iso groups. The chemotaxis index (CI) was evaluated when they reached the young adult stage. The lgg-1::GFP-positive puncta per seam cell were used to determine the autophagic events. The erythropoietin-mediated pathway of autophagy was determined by measuring the genetic expression level of let-363, bec-1, atg-7, atg-5, and lgg-3.

RESULTS

Increased lgg-1::GFP puncta were observed in the Iso, EPO, and EPO-Iso groups. In the Iso group, only the let-363 level decreased significantly as compared to that in the control group (P = 0.009). bec-1 (P < 0.001), atg-5 (P = 0.012), and lgg-3 (P < 0.001) were expressed significantly more in the EPO-Iso group than in the Iso groups. Repeated isoflurane exposure during development decreased the CI. Erythropoietin could restore the decreased CI by isoflurane significantly in the EPO-Iso group.

CONCLUSIONS

Erythropoietin showed neuroprotective effects against AIN and modulated the autophagic pathway in C. elegans. This experimental evidence of erythropoietin-related neuroprotection against AIN may be correlated with the induced autophagic degradation process that was sufficient for handling enhanced autophagy induction in erythropoietin-treated worms.

Children and the Opioid Crisis: We Can Make a Difference

The use of opioid-sparing and opioid-free strategies in children can provide adequate analgesia while decreasing the risk of adverse events and contributing to the ongoing battle against the opioid crisis. However, every child must be evaluated individually so that a safe and efficacious perioperative pain management plan can be created. A working knowledge of the risks and benefits of opioids, nonopioid adjuncts, and regional anesthesia along with the ethical considerations for balancing stewardship and beneficent care is essential to the success of these strategies. As perioperative practitioners caring for children, we have an obligation to consider opioid-sparing and opioid-free strategies to promote overall best outcomes. We can make a difference, one child at a time.

Decabromodiphenyl ethane affects embryonic development by interfering with nuclear F-actin in zygotes and leads to cognitive and social disorders in offspring mice

Decabromodiphenyl ethane (DBDPE) is a novel retardant. DBDPE is used in various flammable consumer products such as electronics, building materials, textiles, and children's toys. The presence of DBDPE in humans makes it extremely urgent to assess the health effects of DBDPE exposure. Here, we used female mice as an animal model to investigate the effects of DBDPE on embryonic development and offspring health. The results showed that 50 μg/kg bw/day of DBDPE exposure did not affect spindle rotation in oocytes after fertilization, but led to a decrease of pronuclei (PN) in zygotes. Further investigation found that DBDPE interferes with the self-assembly of F-actin in PN, resulting in PN reduction, DNA damage, and reduced expression of zygotic genome activating genes, and finally leading to abnormal embryonic development. More importantly, we found that maternal DBDPE exposure did not affect the growth and development of the first generation of offspring (F1) mice, but resulted in behavioral defects in F1 mice. Female F1 mice from DBDPE-exposed mothers exhibited increased motor activity and deficits in social behavior. Both female and male F1 mice from DBDPE-exposed mothers exhibited cognitive memory impairment. These results suggest that DBDPE has developmental toxicity on embryos and has a cross-generational interference effect. It is suggested that people should pay attention to the reproductive toxicity of DBDPE. In addition, it also provides a reference for studying the origin of neurological diseases and indicates that adult diseases caused by environmental pollutants may have begun in the embryonic stage.

Do We Have Viable Protective Strategies against Anesthesia-Induced Developmental Neurotoxicity?

Since its invention, general anesthesia has been an indispensable component of modern surgery. While traditionally considered safe and beneficial in many pathological settings, hundreds of preclinical studies in various animal species have raised concerns about the detrimental and long-lasting consequences that general anesthetics may cause to the developing brain. Clinical evidence of anesthetic neurotoxicity in humans continues to mount as we continue to contemplate how to move forward. Notwithstanding the alarming evidence, millions of children are being anesthetized each year, setting the stage for substantial healthcare burdens in the future. Hence, furthering our knowledge of the molecular underpinnings of anesthesia-induced developmental neurotoxicity is crucially important and should enable us to develop protective strategies so that currently available general anesthetics could be safely used during critical stages of brain development. In this mini-review, we provide a summary of select strategies with primary focus on the mechanisms of neuroprotection and potential for clinical applicability. First, we summarize a diverse group of chemicals with the emphasis on intracellular targets and signal-transduction pathways. We then discuss epigenetic and transgenerational effects of general anesthetics and potential remedies, and also anesthesia-sparing or anesthesia-delaying approaches. Finally, we present evidence of a novel class of anesthetics with a distinct mechanism of action and a promising safety profile.

Tetraethylammonium chloride reduces anaesthetic-induced neurotoxicity in Caenorhabditis elegans and mice

BACKGROUND

If anaesthetics cause permanent cognitive deficits in some children, the implications are enormous, but the molecular causes of anaesthetic-induced neurotoxicity, and consequently possible therapies, are still debated. Anaesthetic exposure early in development can be neurotoxic in the invertebrate Caenorhabditis elegans causing endoplasmic reticulum (ER) stress and defects in chemotaxis during adulthood. We screened this model organism for compounds that alleviated neurotoxicity, and then tested these candidates for efficacy in mice.

METHODS

We screened compounds for alleviation of ER stress induction by isoflurane in C. elegans assayed by induction of a green fluorescent protein (GFP) reporter. Drugs that inhibited ER stress were screened for reduction of the anaesthetic-induced chemotaxis defect. Compounds that alleviated both aspects of neurotoxicity were then blindly tested for the ability to inhibit induction of caspase-3 by isoflurane in P7 mice.

RESULTS

Isoflurane increased ER stress indicated by increased GFP reporter fluorescence (240% increase, P<0.001). Nine compounds reduced induction of ER stress by isoflurane by 90-95% (P<0.001 in all cases). Of these compounds, tetraethylammonium chloride and trehalose also alleviated the isoflurane-induced defect in chemotaxis (trehalose by 44%, P=0.001; tetraethylammonium chloride by 23%, P<0.001). In mouse brain, tetraethylammonium chloride reduced isoflurane-induced caspase staining in the anterior cortical (-54%, P=0.007) and hippocampal regions (-46%, P=0.002).

DISCUSSION

Tetraethylammonium chloride alleviated isoflurane-induced neurotoxicity in two widely divergent species, raising the likelihood that it may have therapeutic value. In C. elegans, ER stress predicts isoflurane-induced neurotoxicity, but is not its cause.

Sevoflurane increases intracellular calcium to induce mitochondrial injury and neuroapoptosis

Sevoflurane is commonly used in clinical anesthesia. However, some reports indicated that Sevoflurane could induce mitochondrial injury and neuroapoptosis. Although the mechanism remains unclear, evidence points to the increase of intracellular calcium after administration of Sevoflurane. Herein, we sought whether the increment of intracellular Ca2+ caused by Sevoflurane administration could induce mitochondrial injury and apoptosis in primary neurons of the hippocampus. Fluo-4-acetoxymethyl ester Ca2+ probe was used for measuring intracellular Ca2+ concentrations. LDH assay, CCK-8 assay, and Western blotting were performed to confirm Sevoflurane-induced neuroapoptosis. ROS, mPTP, and ATP production were assayed to reveal mitochondrial injury. Our results indicated that Sevoflurane increased intracellular Ca2+ and neuronal death. Sevoflurane also elevated ROS and the opening of mPTP, and decreased ATP production in neurons. The expression of cytochrome c, cleaved caspase-9, cleaved caspase-3, and the ratio of Bax/Bcl-2 were also increased. By using calcium channel blocker Nimodipine, the increase of intracellular Ca2+ was attenuated, and the death rate of neurons, the ROS and opening of mPTP, decreased ATP production, the expressions of cytochrome c, cleaved caspase-9, cleaved caspase-3 and the ratio of Bax/Bcl-2 were alleviated. Our study suggested that Sevoflurane could increase intracellular Ca2+ to induce mitochondrial injury and mitochondria-mediated neuroapoptosis in neurons.

Erythropoietin shows gender dependent positive effects on social deficits, learning/memory impairments, neuronal loss and neuroinflammation in the lipopolysaccharide induced rat model of autism

We aimed to evaluate the effects of EPO in the lipopolysaccharide (LPS) induced rat model of autism in terms of social deficits, learning and memory impairments, as well as their neurochemical correlates. Sixteen female Sprague Dawley rats randomly distributed into two equel groups, then were caged with fertile males for mating. At the 10th day of pregnancy, 0.5 ml %0,9 NaCl saline was given to first group, 100 μg/kg LPS was given to second group to induce autism. On postnatal 21th day, forty-eight littermates were divided into four groups as; 8 male, 8 female controls, 16 male and 16 female LPS-exposed. Then, LPS groups were also divided in to two groups as saline (1 mg/kg/day) and EPO 600 U/kg/day groups, and animals were treated 45 days. At 50th day, after behavioral evaluations, brain levels of TNF-α, nerve growth factor (NGF) were measured. Histologically, hippocampal neuronal density and GFAP expression were assessed. Three-chamber sociability and social novelty test, passive avoidance learning test were revealed significant differences among the EPO and control groups. Histologically, hippocampal CA1 & CA3 regions displayed significant alterations regarding gliosis (GFAP-positive cells) and regarding frontal cortical thickness in EPO groups compare to controls. Biochemical measurements of the brain levels of TNF-α and NGF levels showed significant differences between controls and EPO groups. According to our findings EPO treatment has beneficial effects on ASD-like symptoms, learning and memory processes, neuronal loss and neuroinflammation in the LPS induced rat model of autism, with some gender differences through inflammatory and neurotrophic pathways.

Study on the ameliorating effect of miR-221-3p on the nerve cells injury induced by sevoflurane

PURPOSE

Sevoflurane is a widely used anesthetics, however, it has been reported that sevoflurane has neurotoxic effects. Studies have shown that miR-221-3p can ameliorate neuron damage. This study was to investigate whether miR-221-3p could reduce the neurotoxic effect of sevoflurane on nerve cells.

MATERIALS AND METHODS

The rat hippocampal neuron cells were treated with sevoflurane or cultured normally. And we constructed neuron cells that overexpressed or low expression of miR-221-3p in the presence or absence of sevoflurane. The cells were transfected with CDKN1B or siCDKN1B, and co-transfected with miR-221-3p mimic and CDKN1B or miR-221-3p inhibitor and siCDKN1B. Cell viability and apoptosis were detected by CCK-8 and flow cytometer. Target gene of miR-221-3p were predicted by TargetScan and luciferase reporter assay. The expressions of related genes were detected by western blotting and quantitative real-time polymerase chain reaction.

RESULTS

Sevoflurane decreased miR-221-3p level and increased CDKN1B level, inhibited cell viability and promoted apoptosis. Overexpress of miR-221-3p decreased CDKN1B level, up-regulated cell viability and inhibited apoptosis, and reversed the effects of sevoflurane on cell viability and apoptosis, while the effects low expression of miR-221-3p was contrary. CDKN1B was the target gene of miR-221-3p, which inhibited cell viability and promoted apoptosis, and reversed the effects of miR-221-3p mimic, whereas siCDKN1B did the opposite effects.

CONCLUSIONS

Sevoflurane can cause nerve cell injury, and miR-221-3p may promote cell activity and inhibit apoptosis by inhibiting CDKN1B expression, thereby ameliorating cell injury induced by sevoflurane.

Research progress and treatment strategies for anesthetic neurotoxicity

Every year, a large number of infants and young children worldwide are administered general anesthesia. Whether general anesthesia adversely affects the intellectual development and cognitive function of children at a later date remains controversial. Many animal experiments have shown that general anesthetics can cause nerve damage during development, affect synaptic plasticity, and induce apoptosis, and finally affect learning and memory function in adulthood. The neurotoxicity of pediatric anesthetics (PAN) has received extensive attention in the field of anesthesia, which has been listed as a potential problem affecting public health by NFDA of the United States. Previous studies on rodents and non-human primates indicate that inhalation of anesthetics early after birth can induce long-term and sustained impairment of learning and memory function, as well as changes in brain function. Many anti-oxidant drugs, dexmedetomidine, as well as a rich living environment and exercise have been proven to reduce the neurotoxicity of anesthetics. In this paper, we summarize the research progress, molecular mechanisms and current intervention measures of anesthetic neurotoxicity.

Uremic Toxic Blood-Brain Barrier Disruption Mediated by AhR Activation Leads to Cognitive Impairment during Experimental Renal Dysfunction

BACKGROUND

Uremic toxicity may play a role in the elevated risk of developing cognitive impairment found among patients with CKD. Some uremic toxins, like indoxyl sulfate, are agonists of the transcription factor aryl hydrocarbon receptor (AhR), which is widely expressed in the central nervous system and which we previously identified as the receptor of indoxyl sulfate in endothelial cells.

METHODS

To characterize involvement of uremic toxins in cerebral and neurobehavioral abnormalities in three rat models of CKD, we induced CKD in rats by an adenine-rich diet or by 5/6 nephrectomy; we also used AhR^-/- knockout mice overloaded with indoxyl sulfate in drinking water. We assessed neurologic deficits by neurobehavioral tests and blood-brain barrier disruption by SPECT/CT imaging after injection of ^99mTc-DTPA, an imaging marker of blood-brain barrier permeability.

RESULTS

In CKD rats, we found cognitive impairment in the novel object recognition test, the object location task, and social memory tests and an increase of blood-brain barrier permeability associated with renal dysfunction. We found a significant correlation between ^99mTc-DTPA content in brain and both the discrimination index in the novel object recognition test and indoxyl sulfate concentrations in serum. When we added indoxyl sulfate to the drinking water of rats fed an adenine-rich diet, we found an increase in indoxyl sulfate concentrations in serum associated with a stronger impairment in cognition and a higher permeability of the blood-brain barrier. In addition, non-CKD AhR^-/- knockout mice were protected against indoxyl sulfate-induced blood-brain barrier disruption and cognitive impairment.

CONCLUSIONS

AhR activation by indoxyl sulfate, a uremic toxin, leads to blood-brain barrier disruption associated with cognitive impairment in animal models of CKD.

Regions of the basal ganglia and primary olfactory system are most sensitive to neurodegeneration after extended sevoflurane anesthesia in the perinatal rat

Extended general anesthesia early in life is neurotoxic in multiple species. However, little is known about the temporal progression of neurodegeneration after general anesthesia. It is also unknown if a reduction in natural cell death, or an increase in cell creation, occurs as a form of compensation after perinatal anesthesia exposure. The goal of this study was to evaluate markers of neurodegeneration and cellular division at 2, 24, or 72 h after sevoflurane (Sevo) exposure (6 h) in fully oxygenated postnatal day (PND) 7 rats. Neurodegeneration was observed in areas throughout the forebrain, while the largest changes (fold increase above vehicle) were observed in areas associated with either the primary olfactory learning pathways or the basal ganglia. These regions included the indusium griseum (IG, 25-fold), the posterior dorso medial hippocampal CA1 (17-fold), bed nucleus of the stria terminalis (Bed Nuclei STM, 5-fold), the shell of the nucleus accumbens (Acb, 5-fold), caudate/putamen (CPu, 5-fold), globus pallidus (GP, 9-fold) and associated thalamic (11-fold) and cortical regions (5-fold). Sevo neurodegeneration was minimal or undetectable in the ventral tegmentum, substantia nigra, and most of the hypothalamus and frontal cortex. In most brain regions where neurodegeneration was increased 2 h post Sevo exposure, the levels returned to <4-fold above control levels by 24 h. However, in the IG, CA1, GP, anterior thalamus, medial preoptic nucleus of the hypothalamus (MPO), anterior hypothalamic area (AHP), and the amygdaloid nuclei, neurodegeneration at 24 h was double or more than that at 2 h post exposure. Anesthesia exposure causes either a prolonged period of neurodegeneration in certain brain regions, or a distinct secondary degenerative event occurs after the initial insult. Moreover, regions most sensitive to Sevo neurodegeneration did not necessarily coincide with areas of new cell birth, and new cell birth was not consistently affected by Sevo. The profile of anesthesia related neurotoxicity changes with time, and multiple mechanisms of toxicity may exist in a time-dependent fashion.

Acetyl-l-carnitine does not prevent neurodegeneration in a rodent model of prolonged neonatal anesthesia

Many studies have shown that prolonged or repeated use of general anesthesia early in life can cause an increase in neurodegeneration and lasting changes in behavior. While short periods of general anesthesia appear to be safe, there is a concern about the neurotoxic potential of prolonged or repeated general anesthesia in young children. Unfortunately, the use of general anesthesia in children cannot be avoided. It would be a great benefit to develop a strategy to reduce or reverse anesthesia mitigated neurotoxicity. The mechanisms behind anesthesia related neurotoxicity are unknown, but evidence suggests that mitochondrial dysfunction and abnormal energy utilization are involved. Recent research suggests that a class of compounds known as carnitines may be effective at preventing anesthesia related neurotoxicity by influencing fatty acid metabolism in the mitochondria. However, it is unknown if carnitines can provide protection against changes in behavior associated with early life exposure to anesthesia. Accordingly, we evaluated the neuroprotective potential of acetyl-l-carnitine in 7-day old rats. Rat pups were exposed to 6 h of general anesthesia with sevoflurane or a control condition, with and without acetyl-l-carnitine. The oxygenation level of animals was continuously monitored during sevoflurane exposure, and any animal showing signs of hypoxia was removed from the study. Animals exposed to sevoflurane showed clear signs of neurodegeneration 2 h after sevoflurane exposure. The hippocampus, cortex, thalamus, and caudate putamen all had elevated levels of Fluoro-Jade C staining. Despite the elevated levels of Fluoro-Jade C, few behavioral changes were observed in an independent cohort of animals treated with sevoflurane. Furthermore, acetyl-l-carnitine had little impact on levels of Fluoro-Jade C staining in animals treated with sevoflurane. These data suggest that acetyl-l-carnitine may offer little protection again anesthesia related neurotoxicity in fully oxygenated animals.

Synergistic renoprotective effects of sesame oil and erythropoietin on ischemic kidney injury after renal transplantation

In this study, we evaluated the combined therapeutic efficacy of erythropoietin (a hematopoietic hormone produced by the fetal liver and kidney in response to inflammation and apoptosis) and sesame oil (from Sesamum indicum L.) on ischemic kidney injury following kidney transplantation in a rat model. Rats were assigned to the following groups: sham, control, 1000 U/kg erythropoietin, 1 mL/kg sesame oil, 1000 U/kg erythropoietin + 1 mL/kg sesame oil, and positive control. We measured the levels of blood urea nitrogen (BUN), creatinine, alanine aminotransferase (ALT), lipid peroxidation, reactive oxygen species (ROS), reduced glutathione (GSH), antioxidant enzymes, and proinflammatory markers and performed renal histopathological evaluation. The combined erythropoietin and sesame oil treatment significantly reduced BUN, ALT, creatinine, lipid peroxidation, ROS, and proinflammatory markers and GSH and antioxidant enzyme levels. Histopathological examination showed that the combined erythropoietin and sesame oil treatment significantly reduced necrosis. Therefore, combined treatment of sesame oil and erythropoietin may represent an effective therapeutic approach against ischemic kidney injury after kidney transplantation.

Intranasal Administration of Insulin Reduces Chronic Behavioral Abnormality and Neuronal Apoptosis Induced by General Anesthesia in Neonatal Mice

Children, after multiple exposures to general anesthesia, appear to be at an increased risk of developing learning disabilities. Almost all general anesthetics—including sevoflurane, which is commonly used for children—are potentially neurotoxic to the developing brain. Anesthesia exposure during development might also be associated with behavioral deficiencies later in life. To date, there is no treatment to prevent anesthesia-induced neurotoxicity and behavioral changes. In this study, we anesthetized 7-day-old neonatal mice with sevoflurane for 3 h per day for three consecutive days and found that the anesthesia led to mild behavioral abnormalities later in life that were detectable by using the novel object recognition test, Morris water maze, and fear conditioning test. Biochemical and immunohistochemical studies indicate that anesthesia induced a decrease in brain levels of postsynaptic density 95 (PSD95), a postsynaptic marker, and marked activation of neuronal apoptosis in neonatal mice. Importantly, insulin administered through intranasal delivery prior to anesthesia was found to prevent the anesthesia-induced long-term behavioral abnormalities, reduction of PSD95, and activation of neuronal apoptosis. These findings suggest that intranasal insulin administration could be an effective approach to prevent the increased risk of neurotoxicity and chronic damage caused by anesthesia in the developing brain.

Perioperative Outcomes Following Pediatric Cranial Vault Remodeling: Are Improvements Possible?

PURPOSE

The Pediatric Craniofacial Collaborative Group recently reported pooled perioperative data from 31 North American centers performing open cranial vault remodeling procedures. The authors sought to determine if outcomes were different at a single higher-volume center and if identified, ascertain reasons for any differences and propose strategies for improvement.

METHODS

A retrospective review was performed of all open pediatric cranial vault procedures performed at our center during the identical 3.25-year period reported by the Collaborative group, including demographic, perioperative management and outcome data, to permit multiple comparative analyses.

RESULTS

The 310 procedures were performed by our center during this time period, compared to 1223 by the combined 31 institutions (median: 29.5 cases/center; interquartile range: 12-54.5). Multiple outcome differences were found: our higher-volume center had a significantly lower overall red blood cell transfusion rate (≤2 years: 7.5 percent vs 91 percent, P <0.001), those requiring transfusions were transfused considerably smaller volumes (≤2 years: 3.8mL/kg vs 45.3 mL/kg, P <0.001), and exposure to ≥3 blood donors was significantly less (none vs 20 percent, P <0.001). There were no mortalities in either group, but almost all matched adverse events were less common at our center. Both the intensive care unit and hospital lengths of stay were significantly shorter at our center (1 vs 2 days, 2 vs 4 days, both P <0.001).

CONCLUSIONS

Perioperative outcomes following pediatric craniosynostosis corrections performed at a single higher-volume center compare favorably to median national data. Multiple potential strategies to reduce blood utilization, minimize perioperative complications, and shorten hospitalizations are proposed.

The Neuroprotective Effect of Hemin and the Related Mechanism in Sevoflurane Exposed Neonatal Rats

Background

Many studies have reported that sevoflurane can increase neuronal apoptosis and result in cognitive deficits in rodents. Although neurotoxicity may be associated with mitochondrial dysfunction and oxidative stress, the exact mechanism remains unclear. In order to evaluate potential treatment therapies, we studied the effects of hemin on neurotoxicity of neonatal rat sevoflurane exposure.

Methods

Postnatal day (P) seven rats were assigned randomly to four groups; (1) group C: non-anesthesia, (2) group H: intraperitoneal hemin (50 mg kg^-1) treatment on days 5 and 6, (3) group S: 3% sevoflurane exposure for 4 h, and (4) group SH: hemin treatment + sevoflurane exposure. The expression of neuroglobin in neonatal hippocampus was determined by western blot and immunohistochemistry. Neuroglobin was localized by immunofluorescence. Western blot for the expression of cleaved caspase-3 and TUNEL were used to detect neonatal hippocampal apoptosis, and cytochrome c was used to evaluate mitochondrial function. Drp-1 and Mfn-2 immunoblotting were used to assess mitochondrial dynamics. The Morris water maze test was performed to detect cognitive function in the rats on P30.

Results

Exposure to sevoflurane increased the expression of cleaved caspase-3, cytochrome c, and Drp1 in the neonatal hippocampus and resulted in cognitive deficiency but decreased expression of Mfn2. Hemin reduced apoptosis, improved mitochondrial dynamics and ameliorated the cognitive impairment caused by sevoflurane exposure.

Conclusion

Hemin reduced neuronal apoptosis, improved mitochondrial dynamics and protected against cognitive deficits induced by sevoflurane in neonatal rats. This neuroprotective effect may be achieved by increasing the expression of neuroglobin.

Sevoflurane induces cognitive impairment in young mice via autophagy

Background

Anesthesia may induce neurotoxicity and neurocognitive impairment in young mice. However, the underlying mechanism remains largely to be determined. Meanwhile, autophagy is involved in brain development and contributes to neurodegenerative diseases. We, therefore, set out to determine the effects of sevoflurane on autophagy in the hippocampus of young mice and on cognitive function in the mice.

Methods

Six day-old mice received 3% sevoflurane, for two hours daily, on postnatal days (P) 6, 7 and 8. We then decapitated the mice and harvested the hippocampus of the young mice at P8. The level of LC3, the ratio of LC3-II to LC3-I, and SQSTM1/p62 level associated with the autophagy in the hippocampus of the mice were assessed by using Western blotting. We used different groups of mice for behavioral testing via the Morris Water Maze from P31 to P37.

Results

The anesthetic sevoflurane increased the level of LC3-II and ratio of LC3-II/LC3-I, decreased the p62 level in the hippocampus of the young mice, and induced cognitive impairment in the mice. 3-Methyladenine, the inhibitor of autophagy, attenuated the activation of autophagy and ameliorated the cognitive impairment induced by sevoflurane in the young mice.

Conclusion

These data showed that sevoflurane anesthesia might induce cognitive impairment in the young mice via activation of autophagy in the hippocampus of the young mice. These findings from the proof of concept studies have established a system and suggest the role of autophagy in anesthesia neurotoxicity and cognitive impairment in the young mice, pending further investigation.

Pre-administration of luteoline attenuates neonatal sevoflurane-induced neurotoxicity in mice

Sevoflurane is a widely used inhaled anesthetic, which triggers neuroapoptosis and oxidative damage in the developing central nervous system and cognitive dysfunction later in life. However, no effective therapeutic strategy for sevoflurane-induced deleterious effects is well developed. The purpose of the present study was to explore whether luteoline could attenuate neonatal sevoflurane exposure-triggered neurotoxicity. In this study, six-day-old C57BL/6 mice were pretreated with luteoline (30, 60 mg/kg) intraperitoneally for 30 min before exposed to 3% sevoflurane 6 h consecutively. We first examined the effects of luteoline on hippocampal neuron apoptosis, inflammation and oxidative stress 18 h post anesthesia. The spatial learning and memory performance was measured using Morris water maze test from postnatal day 31 to 38. The results showed that luteoline ameliorated neuronal apoptosis as evidenced by decrease of apoptotic cells, downregulation of the cleavage levels of caspase-3 and PRAP, and inactivation of caspase-3. Moreover, luteoline significantly decreased protein expressions of inflammatory cytokines (IL-1β, IL-18 and TNF-α), inhibited NF-кB/NLRP3 pathway (NF-кB, NLRP3, ASC and caspase-1) and suppressed NF-кB activity. Our analyses indicated that luteoline had a significant effect on decreasing the contents of ROS and MDA, elevating the activity of SOD, and ultimately improving spatial learning and memory deficits of mice. In summary, our findings confirm that the attenuation of luteoline on sevoflurane-induced spatial learning and memory impairment later is associated with inhibition of hippocampal neuron apoptosis, inflammation and oxidative stress early. Luteoline might be a potential therapeutic for sevoflurane anesthesia-induced neurobehavioral dysfunction.

Erythropoietin Protects Against Cognitive Impairment and Hippocampal Neurodegeneration in Diabetic Mice

Administration of erythropoietin (EPO) is neuroprotective against a variety of experimentally-induced neurological disorders. The aim was to determine if EPO protects against hippocampal neurodegeneration as well as impairment of cognition and motor performance, associated with long-term diabetes. BALB/c mice were randomly allocated between control, diabetic and EPO-treated diabetic groups. EPO-treated diabetic mice were administered EPO 0.05 U/kg/day i.p. three times/week for 10 weeks. Cognition was assessed by Morris water maze. Brain samples were processed for light microscopic evaluation of hippocampus. Controls showed gradual improvement of cognitive performance in water maze when comparing latency (p < 0.01) and distance swum to reach the platform (p = 0.001). There was a similar trend for improvement in EPO-treated diabetics (p < 0.001). Latency did not improve in diabetic animals indicating lack of learning (p = 0.79). In probe trials, controls and EPO-treated diabetics spent more time in the training quadrant than expected by chance (p < 0.001). Diabetics did not show memory recall behavior; performance was significantly worse than expected by chance (p = 0.023). In diabetics, there was neurodegeneration in hippocampus and reduction in number of granule cells (p < 0.01) in the dentate gyrus. EPO treatment improved these neurodegenerative changes and preserved numbers of granule cells (p < 0.1, compared to controls). Erythropoietin treatment is protective against cognitive deficits and hippocampal neurodegeneration in diabetic mice.

Sevoflurane affects neurogenesis through cell cycle arrest via inhibiting wnt/β-catenin signaling pathway in mouse neural stem cells

AIMS

The development of central nervous system requires proliferation of neural stem cells followed by differentiation. Cell cycle parameters are closely related with cell fate specification and differentiation. Recent researches indicated that wnt/β-catenin signaling pathway might cause proliferation inhibition and differentiation abnormality through interfering NSCs cell cycle. Our previous research also showed that multiple sevoflurane exposure to neural stem cells inhibited proliferation via repressing transcription factor Pax6 and cyclin D1 through inhibiting wnt/β-catenin pathway. All above encouraged us to figure out the effect of sevoflurane on cell cycle and neurogenesis.

MAIN METHODS

Primary mouse cultured neural stem cells were used and exposed to 4.1% sevoflurane for 6 h in this study. The expression of β-catenin, GSK-3β, c-myc and cyclin D1 were determined by western blot and qRT-PCR. FACS was used to measure the cell cycle. The proliferation of NSCs was evaluated by EdU staining while the differentiation was evaluated by Tuj1 and GFAP staining on immunocytochemistry.

KEY FINDINGS

We found that exposure to sevoflurane at a concentration of 4.1% for 6 h induced inhibition of wnt/β-catenin pathway, cell cycle arrest at G0/G1 phase and an earlier switch from proliferation to differentiation. GSK-3β specific inhibitor, CHIR99021, attenuated sevoflurane-induced cell cycle arrest and abnormality of neurogenesis in neural stem cells.

SIGNIFICANCE

Our research suggested that sevoflurane arrested cell cycle at G0/G1 phase through inhibition of wnt/β-catenin signaling pathway thus resulting in a premature differentiation in NSCs. This study presents a deeper understanding of the mechanism on cognitive impairment by sevoflurane exposure.

Renoprotective effect of erythropoietin via modulation of the STAT6/MAPK/NF-κB pathway in ischemia/reperfusion injury after renal transplantation

Ischemia/reperfusion injury (IRI) commonly occurs in renal transplantation. Erythropoietin (EPO) exerts a protective effect in IRI. To investigate the underlying molecular mechanism, rat models of renal IRI were established and treated with EPO and/or lentivirus-mediated EPO-siRNA, the signal transducer and activator of transcription 6 (STAT6) inhibitor AS1517499, the JNK inhibitor SP600125, the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580, and the nuclear factor (NF)-κB inhibitor lactacystin. Histological examination revealed that EPO protected the kidney from IRI, through decreasing the extent of tissue congestion and inflammatory cell infiltration; however, EPO siRNA did not exert the same protective effect. In addition, the EPO level was inversely associated with renal IRI. EPO downregulated the expression of interferon-γ, interleukin (IL)-4, creatinine and caspase-3, and upregulated the expression of IL-10, thymic stromal lymphopoietin, STAT6, p-JNK and p-p38, while the opposite effects were observed with the administration of EPO-siRNA and the specific respective inhibitors. Further results revealed that MAPK (p-JNK and p-p38) acted upstream of NF-κB, and that NF-κB signaling regulated the expression of caspase-1 and -3, which may be responsible for the cytotoxicity associated with IRI. Taken together, the results of the present study demonstrated that EPO exerted a protective effect in renal IRI via the STAT6/MAPK/NF-κB pathway. This protective effect of EPO may improve reperfusion tolerance in ischemic kidneys and benefit transplant recipients.

Propofol's Effects on the Fetal Brain for Non-Obstetric Surgery

While the use of Propofol has been increasing in usage for general surgical procedures since its release to market, there has been little work done on its potential link to neurotoxicity in humans. Only recently, following the release of a warning label from the United States Food and Drug Administration (USFDA) regarding a potential link to "neurotoxicity" in the neonate, did the surgical and anesthesiology communities become more aware of its potential for harm. Given the widespread use of this drug in clinical practice, the warning label naturally raised controversy regarding intrapartum Propofol usage. While intended to generate further studies, the lack of a viable anesthetic alternative raises issues regarding its current usage for surgical procedures in pregnant women. To answer the question whether current evidence is supportive of Propofol usage at its current levels in pregnant women, this review summarizes available evidence of fetal Propofol exposure in animal studies.

Recent Insights Into Molecular Mechanisms of Propofol-Induced Developmental Neurotoxicity: Implications for the Protective Strategies

Mounting evidence has demonstrated that general anesthetics could induce developmental neurotoxicity, including acute widespread neuronal cell death, followed by long-term memory and learning abnormalities. Propofol is a commonly used intravenous anesthetic agent for the induction and maintenance of anesthesia and procedural and critical care sedation in children. Compared with other anesthetic drugs, little information is available on its potential contributions to neurotoxicity. Growing evidence from multiple experimental models showed a similar neurotoxic effect of propofol as observed in other anesthetic drugs, raising serious concerns regarding pediatric propofol anesthesia. The aim of this review is to summarize the current findings of propofol-induced developmental neurotoxicity. We first present the evidence of neurotoxicity from animal models, animal cell culture, and human stem cell-derived neuron culture studies. We then discuss the mechanism of propofol-induced developmental neurotoxicity, such as increased cell death in neurons and oligodendrocytes, dysregulation of neurogenesis, abnormal dendritic development, and decreases in neurotrophic factor expression. Recent findings of complex mechanisms of propofol action, including alterations in microRNAs and mitochondrial fission, are discussed as well. An understanding of the toxic effect of propofol and the underlying mechanisms may help to develop effective novel protective or therapeutic strategies for avoiding the neurotoxicity in the developing human brain.

Neuroprotective Effect of Erythropoietin on Phenylhydrazine-Induced Hemolytic Hyperbilirubinemia in Neonatal Rats

Neonatal unconjugated hyperbilirubinemia might cause severe bilirubin neurotoxicity in especially hemolytic conditions. The study aimed to elucidate the potential neuroprotective effects of erythropoietin (EPO) in hemolysis-induced hyperbilirubinemia. In newborn rats, hyperbilirubinemia secondary to hemolysis was induced by injecting with phenylhydrazine hydrochloride (PHZ) and rats were injected with either vehicle or EPO. At 54th hour of the PHZ injection, rats were decapitated. Serum levels of TNF-α, IL-1β, IL-10, brain-derived neurotrophic factor (BDNF) and S100-B and brain malondialdehyde, glutathione levels and myeloperoxidase activities were measured. TUNEL staining and NF-κB expression were evaluated. As compared to control pups, in vehicle-treated PHZ group, TNF-α and IL-1β levels, malondialdehyde level and myeloperoxidase activity were increased with concomitant decreases in IL-10 and glutathione. All EPO regimens reversed PHZ-induced alterations in IL-10, TNF-α, malondialdehyde and glutathione levels. Three-day-treatment abolished increases in myeloperoxidase activity and IL-1β levels, while BDNF and S100-B were elevated. Increased TUNEL (+) cells and NF-κB expressions in the brain of PHZ group were reduced in the 3-day-treated group. EPO exerted anti-inflammatory effects on PHZ-induced neural damage in newborn rats, while the neuroprotection was more obvious when the treatments were repeated successively. The results suggest that EPO treatment may have a therapeutic potential in supporting neuroplasticity in the hyperbilirubinemic neonates.

Erythropoietin diminishes isoflurane-induced apoptosis in rat frontal cortex

BACKGROUND

During the brain growth spurt, anesthetic drugs can cause cellular and behavioral changes in the developing brain. The aim of this study was to determine the neuroprotective effect of erythropoietin after isoflurane anesthesia in rat pups.

METHODS

A total of 42, 7-day-old Wistar rats were divided into three groups. Control group (GC; n = 14): Rats breathed 100% oxygen for 6 h; Isoflurane group (GI; n = 14): Rats were exposed to 1.5% isoflurane in 100% oxygen for 6 h; Isoflurane + erythropoietin group (GIE; n = 14): 1000 IU·kg(-1) (intraperitoneal; IP) Erythropoietin was administered after isoflurane anesthesia. Each group was divided into two groups for pathology and learning and memory tests. Silver, caspase-3, and fluoro-jade C staining were used for detecting apoptotic cells in frontal cortex, striatum, hippocampus, thalamus, and amygdala. Morris water maze was used to evaluate learning and memory.

RESULTS

There was a significant increase in apoptotic cell count after isoflurane anesthesia in the frontal cortex when compared with control group (29.0 ± 9.27 vs 3.28 ± 0.75 [P = 0.002], 20.85 ± 10.94 vs 2.0 ± 0.81 [P = 0.002] and 24.57 ± 10.4 vs 5.14 ± 0.69 [P = 0.024] with silver, caspase-3, and fluoro-jade C staining, respectively). The apoptotic cell count in the frontal cortex was significantly higher in GIE than GC with caspase-3 staining (9.14 ± 3.13 vs 2.0 ± 0.81, P = 0.002). The apoptotic cell count in GIE was significantly reduced in the frontal cortex when compared with GI (4.0 ± 0.81 vs 29.0 ± 9.27 [P = 0.002], 9.14 ± 3.13 vs 20.85 ± 10.94 [P = 0.04] and 4.0 ± 1.63 vs 24.57 ± 10.4 [P = 0.012] with silver, caspase-3, and fluoro-jade C staining, respectively).

CONCLUSIONS

A total of 1000 IU·kg(-1) IP erythropoietin diminished isoflurane-induced neuroapoptosis. Further experimental studies have to be planned to reveal the optimal dose and timing of erythropoietin before adaptation to clinical practice.

Propofol-Induced Neurotoxicity in the Fetal Animal Brain and Developments in Modifying These Effects-An Updated Review of Propofol Fetal Exposure in Laboratory Animal Studies

In the past twenty years, evidence of neurotoxicity in the developing brain in animal studies from exposure to several general anesthetics has been accumulating. Propofol, a commonly used general anesthetic medication, administered during synaptogenesis, may trigger widespread apoptotic neurodegeneration in the developing brain and long-term neurobehavioral disturbances in both rodents and non-human primates. Despite the growing evidence of the potential neurotoxicity of different anesthetic agents in animal studies, there is no concrete evidence that humans may be similarly affected. However, given the growing evidence of the neurotoxic effects of anesthetics in laboratory studies, it is prudent to further investigate the mechanisms causing these effects and potential ways to mitigate them. Here, we review multiple studies that investigate the effects of in utero propofol exposure and the developmental agents that may modify these deleterious effects.

Neuronal apoptosis may not contribute to the long-term cognitive dysfunction induced by a brief exposure to 2% sevoflurane in developing rats

BACKGROUND

Sevoflurane is an inhaled anesthetic commonly used in the pediatric. Recent animal studies suggest that early exposure to high concentration of sevoflurane for a long duration can induce neuroapoptosis and later cognitive dysfunction. However, the neurodevelopmental impact induced by lower concentration and shorter exposure duration of sevoflurane is unclear. To investigate whether early exposure to 2% concentration of sevoflurane for a short duration (clinically relevant usage of sevoflurane) can also induce neuroapoptosis and later cognitive dysfunction.

METHODS

Rat pups were subjected to control group, 2% sevoflurane for 3h and 3% sevoflurane for 6h. TUNEL assay and apoptotic enzyme cleaved caspase-3 measured by western blot were used for detection of neuronal apoptosis in frontal cortex and CA1 region of hippocampus 24 after sevoflurane treatment. Long-term cognitive function was evaluated by Morris water maze and passive avoidance test as the rats grew up.

RESULTS

The apoptotic levels in frontal cortex and CA1 region were significantly increased after rats exposed to 3% sevoflurane for 6h (P<0.05), but not 2% sevoflurane for 3h (P>0.05). Exposure to both 2% sevoflurane for 3h and 3% sevoflurane for 6h could cause long-term cognitive dysfunction and animals exposed to 3% sevoflurane for 6h exhibited worse neurodevelopmental outcomes (P<0.05).

CONCLUSION

It was suggested that neuronal apoptosis might not contribute to long-term cognitive dysfunction induced by 2% concentration and short exposure time of sevoflurane. Our findings also suggested that the mechanisms of sevoflurane-induced neurodevelopmental impact might be various, depending on the concentration and exposure duration.

Protection against ischemia/reperfusion‑induced renal injury by co‑treatment with erythropoietin and sodium selenite

Ischemia/reperfusion injury (IRI) has lzong been an area of concern and focus of investigations. Erythropoietin (EPO) exhibits multiple protective effects, and selenium is an antioxidant trace element in the body, however, there have been no reports concerning the effects of EPO combined with sodium selenite on IRI. In the present study, a mouse model of renal IRI (RIRI) was pre–treated with EPO and sodium selenite to determine the most appropriate combination ratio of the two for further investigation. The results revealed that EPO and sodium selenite had synergistic protective effects in RIRI. EPO was identified as the predominant treatment component, with sodium selenite serving as an adjuvant, and combination treatment was markedly more effective, compared with treatment with either drug alone. The optimal ratio of treatment was 10:1 (10 IU EPO: 1 µg sodium selenite). The results indicated that RIRI markedly induced renal injury, as evidenced by elevated levels of blood urea nitrogen (BUN), as well as higher pathological scores, based on hematoxylin and eosin staining. Pre–treatment with EPO and sodium selenite significantly decreased serum expression levels of BUN and malonaldehyde, and increased the expression levels of superoxide dismutase, glutathione peroxidase and nitric oxide (NO), compared with the model group. Furthermore, co treatment with EPO and sodium selenite upregulated the protein expression levels of phosphatidylinositol 3 kinase (PI3K) in renal tissue samples. Together, the results suggested that co administration of EPO and sodium selenite effectively ameliorates IRI induced renal injury by reducing oxidative stress and activating the PI3K/NO signaling pathway.

Effect of apoptosis in neural stem cells treated with sevoflurane

BACKGROUND

At present, sevoflurane inhalation anesthesia used on infants is well-known. But long-time exposure to inhalation anesthetic could cause neurologic disorder, especially nerve degeneration in infant and developing brain. The central nervous system degeneration of infants could affect the memory and cognitive function. γ-Aminobutyric acid (GABA) is a known inhibitory neurotransmitter in central nervous system. Inhalation anesthetic sevoflurane may activate GABAA receptor to inhibit central nervous system, leading to apoptosis of neural degeneration, cognitive dysfunction in the critical period of brain development.

METHODS

Neural stem cells were derived from Wistar embryos, cultured in vitro. Third generation of neural stem cells were randomly divided into four groups according to cultured suspension: Sevoflurane group (Group S), GABAA receptor antagonists, Bicuculline group (Group B), Sevoflurane + GABAA receptor antagonists, Bicuculline group (Group S + B), dimethyl sulphoxide (DMSO) group (Group D). Group B and Group D did not receive sevoflurane preconditioning. Group S and Group S + B were pretreated with 1 minimum alveolar concentration (MAC) sevoflurane for 0 h, 3 h, 6 h, and 12 h. Group S + B and Group B were pretreated with bicuculline (10 uM). Group D was treated with DMSO (10 uL/mL). After treatments above, all groups were cultured for 48 h. Then we measured the cells viability by Cell Counting Kit (CCK-8) assay, cytotoxicity by Lactate Dehydrogenase (LDH) assay, apoptosis ratio with Annexin V/propidium iodide (PI) staining by flow cytometry, and the expression of GABAAR, anti-apoptotic protein Bcl-2, pro-apoptotic protein Bax and Caspase-3 by western blotting.

RESULTS

After exposing to sevoflurane for 0 h, 3 h, 6 h, and 12 h with 1MAC, we found that cell viability obviously decreased and cytotoxicity increased in time-dependent way. And Annexin V/PI staining indicated increased apoptosis ratio by flow cytometry. The protein level of GABAA receptor, pro-apoptotic protein Bax and apoptosis protein Caspase-3 increased; while anti-apoptotic protein Bcl-2 decreased. And bicuculline could reverse all detrimental results caused by sevoflurane.

CONCLUSION

Sevoflurane can inhibit the central nervous system by activating GABAA, resulting in apoptosis of neural stem cells, thus leading to the NSCs degeneration.

Pre-administration of curcumin prevents neonatal sevoflurane exposure-induced neurobehavioral abnormalities in mice

Sevoflurane, a commonly used inhaled anesthetic, can induce neuronal apoptosis in the developing rodent brain and correlate with functional neurological impairment later in life. However, the mechanisms underlying these deleterious effects of sevoflurane remain unclear and no effective treatment is currently available. Herein, the authors investigated whether curcumin can prevent the sevoflurane anesthesia-induced cognitive impairment in mice. Six-day-old C57BL/6 mice were exposed to 3% sevoflurane 2h daily for 3 consecutive days and were treated with curcumin at the dose of 20 mg/kg or vehicle 30 min before the sevoflurane anesthesia from postnatal days 6 (P6) to P8. Cognitive functions were evaluated by open field, Morris water maze, and fear conditioning tests on P61, P63-69, and P77-78, respectively. In another separate experiment, mice were killed on day P8 or P78, and the brain tissues were harvested and then subjected to biochemistry studies. Our results showed that repeated neonatal sevoflurane exposure led to significant cognitive impairment later in life, which was associated with increased neuronal apoptosis, neuroinflammation, oxidative nitrosative stress, and decreased memory related proteins. By contrast, pre-administration of curcumin ameliorated early neuronal apoptosis, neuroinflammation, oxidative nitrosative stress, memory related proteins, and later cognitive dysfunction. In conclusion, our data suggested that curcumin pre-administration can prevent the sevoflurane exposure-induced cognitive impairment later in life, which may be partly attributed to its ability to attenuate the neural apoptosis, inflammation, and oxidative nitrosative stress in mouse brain.