Repeated administration of ketamine may lead to neuronal degeneration in the developing rat brain

Dexmedetomidine directly binds to and inhibits Toll-like receptor 4

BACKGROUND

While a number of anesthetics has been shown potentially associated with neurotoxicity in the developing brain, dexmedetomidine, a drug that was rather recently introduced into the perioperative setting, is considered beneficial from neurological wellbeing. However, the underlying mechanism of how dexmedetomidine affects brain health remains to be determined. Based on our recent study, we hypothesized that dexmedetomidine would directly bind to and inhibit Toll-like receptor 4 (TLR4), a critical receptor largely expressed in microglia and responsible for neurological insult.

METHODS

We used TLR4 reporter assays to test if dexmedetomidine attenuates TLR4 activation. Furthermore, a direct binding of dexmedetomidine on TLR4 was tested using photoactivatable medetomidine. Lastly, the effect of dexmedetomidine on ketamine (anesthetic)-induced neurotoxicity was tested in rat pups (P7).

RESULTS

We showed that dexmedetomidine attenuated TLR4 activation using reporter assay (IC50 = 5.8 µg/mL). Photoactivatable dexmedetomidine delineated its direct binding sites on TLR4. We also showed that dexmedetomidine attenuated microglia activation both in vitro and in vivo.

DISCUSSION

We proposed a novel mechanism of dexmedetomidine-mediated neuroprotection.

Ketamine modulates disrupted in schizophrenia-1/glycogen synthase kinase-3β interaction

Introduction

Disrupted in schizophrenia-1 (DISC1) is a scaffolding protein whose mutated form has been linked to schizophrenia, bipolar affective disorders, and recurrent major depression. DISC1 regulates multiple signaling pathways involved in neurite outgrowth and cortical development and binds directly to glycogen synthase kinase-3β (GSK-3β). Since ketamine activates GSK-3β, we examined the impact of ketamine on DISC1 and GSK-3β expression.

Methods

Postnatal day 7 rat pups were treated with ketamine with and without the non-specific GSK-3β antagonist, lithium. Cleaved-caspase-3, GSK-3β and DISC1 levels were measured by immunoblots and DISC1 co-localization in neurons by immunofluorescence. Binding of DISC1 to GSK-3β was determined by co-immunoprecipitation. Neurite outgrowth was determined by measuring dendrite and axon length in primary neuronal cell cultures treated with ketamine and lithium.

Results

Ketamine decreased DISC1 in a dose and time-dependent manner. This corresponded to decreases in phosphorylated GSK-3β, which implicates increased GSK-3β activity. Lithium significantly attenuated ketamine-induced decrease in DISC1 levels. Ketamine decreased co-immunoprecipitation of DISC1 with GSK-3β and axonal length.

Conclusion

These findings confirmed that acute administration of ketamine decreases in DISC1 levels and axonal growth. Lithium reversed this effect. This interaction provides a link between DISC1 and ketamine-induced neurodegeneration.

The role of NMDARs in the anesthetic and antidepressant effects of ketamine

BACKGROUND

As a phencyclidine (PCP) analog, ketamine can generate rapid-onset and substantial anesthetic effects. Contrary to traditional anesthetics, ketamine is a dissociative anesthetic and can induce loss of consciousness in patients. Recently, the subanaesthetic dose of ketamine was found to produce rapid-onset and lasting antidepressant effects.

AIM

However, how different concentrations of ketamine can induce diverse actions remains unclear. Furthermore, the molecular mechanisms underlying the NMDAR-mediated anesthetic and antidepressant effects of ketamine are not fully understood.

METHOD

In this review, we have introduced ketamine and its metabolism, summarized recent advances in the molecular mechanisms underlying NMDAR inhibition in the anesthetic and antidepressant effects of ketamine, explored the possible functions of NMDAR subunits in the effects of ketamine, and discussed the future directions of ketamine-based anesthetic and antidepressant drugs.

RESULT

Both the anesthetic and antidepressant effects of ketamine were thought to be mediated by N-methyl-D-aspartate receptor (NMDAR) inhibition.

CONCLUSION

The roles of NMDARs have been extensively studied in the anaesthetic effects of ketamine. However, the roles of NMDARs in antidepressant effects of ketamine are complicated and controversial.

Lipoxin A4 methyl ester attenuated ketamine-induced neurotoxicity in SH-SY5Y cells via regulating leptin pathway

Ketamine, the widely used intravenous anesthetic, has been reported to cause neurotoxicity and disturbs normal neurogenesis. However, the efficacy of current treatment strategies targeting ketamine's neurotoxicity remains limited. Lipoxin A4 methyl ester (LXA4 ME) is relatively stable lipoxin analog, which serves an important role in protecting against early brain injury. The purpose of this study was to investigate the protective effect of LXA4 ME on ketamine-caused cytotoxicity in SH-SY5Y cells, as well as the underlying mechanisms. Cell viability, apoptosis and endoplasmic reticulum stress (ER stress) were detected by adopting experimental techniques including CCK-8 assay, flow cytometry, western blotting and transmission electron microscope. Furthermore, examining the expression of leptin and its receptor (LepRb), we also measured the levels of activation of the leptin signaling pathway. Our results showed that LXA4 ME intervention promoted the cell viability, inhibited cell apoptosis, and reduced the expression of ER stress related protein and morphological changes induced by ketamine. In addition, inhibition of leptin signaling pathway caused by ketamine could be reversed by LXA4 ME. However, as the specific inhibitor of leptin pathway, leptin antagonist triple mutant human recombinant (leptin tA) attenuated the cytoprotective effect of LXA4 ME against ketamine-induced neurotoxicity. In conclusion, our findings demonstrated LXA4 ME could exert a neuroprotective effect on ketamine-induced neuronal injury via activation of the leptin signaling pathway.

Nano-hesperetin attenuates ketamine-induced schizophrenia-like symptoms in mice: participation of antioxidant parameters

RATIONALE

Antioxidant natural herb hesperetin (Hst) offers powerful medicinal properties. Despite having noticeable antioxidant properties, it has limited absorption, which is a major pharmacological obstacle.

OBJECTIVES

The goal of the current investigation was to determine if Hst and nano-Hst might protect mice against oxidative stress and schizophrenia (SCZ)-like behaviors brought on by ketamine (KET).

METHODS

Seven treatment groups (n=7) were created for the animals. For 10 days, they received distilled water or KET (10 mg/kg) intraperitoneally (i.p). From the 11th to the 40th day, they received daily oral administration of Hst and nano-Hst (10, 20 mg/kg) or vehicle. With the use of the forced swimming test (FST), open field test (OFT), and novel object recognition test (NORT), SCZ-like behaviors were evaluated. Malondialdehyde (MDA) and glutathione levels and antioxidant enzyme activities were assessed in the cerebral cortex.

RESULTS

Our findings displayed that behavioral disorders induced by KET would be improved by nano-Hst treated. MDA levels were much lower after treatment with nano-Hst, and brain antioxidant levels and activities were noticeably higher. The mice treated with nano-Hst had improved outcomes in the behavioral and biochemical tests when compared to the Hst group.

CONCLUSIONS

Our study's findings showed that nano-Hst had a stronger neuroprotective impact than Hst. In cerebral cortex tissues, nano-Hst treatment dramatically reduced KET-induced (SCZ)-like behavior and oxidative stress indicators. As a result, nano-Hst may have more therapeutic potential and may be effective in treating behavioral impairments and oxidative damage brought on by KET.

Effects of recurrent ketamine exposure on brain histopathology in juvenile rats

BACKGROUND

Ketamine (KET) is a commonly used anesthetic agent. However, several previous studies reported that KET leads to neuronal damage in neurodevelopmental stages and has neuroprotective effects. The present experimental study aimed to determine the undesirable histopathological effects of KET in the cerebral cortex, striatum, and hippocampus after recurrent KET administration in juvenile rats.

METHODS

After ethical approval was obtained, 32 juvenile male Wistar Albino rats were randomized into four groups: 1 mg/kg serum saline intraperitoneally (i.p.), 5 mg/kg KET i.p., 20 mg/kg KET i.p., and 50 mg/kg KET i.p. KET was administered for three consecutive days at three-h intervals in three doses. Ten days after the last KET dose, the rats were sacrificed. Cerebral hemispheres were fixed. Hematoxylin and eosin stain was used for morphometric analysis. Hippocampi were evaluated by immunohistochemistry with anticleaved caspase-3 antibodies. Statistical analysis was conducted with SPSS 21 software using the ANOVA test and Bonferroni post hoc analysis method.

RESULTS

The experimental study findings revealed no difference between the groups' cell counts or sizes in cortical morphometry. No degenerative changes were observed in pyramidal and granular cells in the striatum. Mild gliosis was observed in the 20 mg/kg and 50 mg/kg KET administration groups. Immuno-histo-chemical analysis was conducted to determine apoptosis in the CA1 region of the hippocampus and revealed that caspase-3 positivity increased with the KET dose. However, there was no statistical difference between the groups. While it was lower than the control group in the 5 mg/kg KET group, it was similar to the control group in the 20 mg/kg KET group and higher in the 50 mg/kg KET group (p > 0.05).

DISCUSSION

: Repetitive KET exposure did not significantly affect juvenile cerebral morphology and apoptosis in hippocampal cells.

A systematic review of therapeutic ketamine use in children and adolescents with treatment-resistant mood disorders

Suicide is the second leading cause of death in the United States among individuals aged 10-24, and severe youth depression is often refractory to the current standards of care. Many studies have demonstrated the efficacy of ketamine in reducing depressive symptoms in adults with treatment-resistant mood disorders, though few studies utilizing ketamine in youth populations exist. This systematic review examines the current state of evidence for ketamine use in children with treatment-resistant mood disorders. We conducted a search utilizing two electronic databases for English-language studies investigating the therapeutic effects and side effect profile of ketamine in youth ≤ 19 years of age with a diagnosis of a treatment-resistant mood disorder. Analysis included subjects with treatment-resistant depression with and without psychotic features and with bipolar disorder. Primary outcome measures included the following scales: Montgomery-Asberg Depression Rating Scale, Children's Depression Rating Scale, Children's Depression Rating Scale Revised, Child Bipolar Questionnaire, Overt Aggression Scale, Yale-Brown Obsessive-Compulsive Scale, and Scale for Suicidal Ideation. Four published studies were identified that investigated therapeutic ketamine use in youth for the primary purpose of treating a treatment-resistant psychiatric disorder. Three additional studies that did not meet eligibility criteria were identified and discussed. Ketamine was shown in youth to generally improve depressive symptoms, decrease acute suicidality, and reduce mood lability, though a number of subjects remained resistant to its treatment. These findings substantiate the need for further longitudinal studies investigating ketamine's long-term safety, its efficacy, and abuse potential in the youth.

The effects of early anesthesia on neurodevelopment: A systematic review

BACKGROUND

There is growing concern regarding the impact of general anesthesia on neurodevelopment in children. Pre-clinical animal studies have linked anesthetic exposure to abnormal central nervous system development, but it is unclear whether these results translate into humans. The purpose of this systematic review from the American Pediatric Surgical Association (APSA) Outcomes and Evidence-Based Practice (OEBP) Committee was to review, summarize, and evaluate the evidence regarding the neurodevelopmental impact of general anesthesia on children and identify factors that may affect the risk of neurotoxicity.

METHODS

Medline, Cochrane, Embase, Web of Science, and Scopus databases were queried for articles published up to and including December 2017 using the search terms "general anesthesia and neurodevelopment" as well as specific anesthetic agents. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to screen manuscripts for inclusion in the review. A consensus statement of recommendations in response to each study question was synthesized based upon the best available evidence.

RESULTS

In total, 493 titles were initially identified, with 56 articles selected for full analysis and 44 included for review. Based on currently available developmental assessment tools, a single exposure to general anesthesia does not appear to have a significant effect on general neurodevelopment, although prolonged or multiple anesthetic exposures may have some adverse effects. Exposure to general anesthesia may affect different domains of development at different ages. Regional anesthetic techniques with the addition of dexmedetomidine and/or some intravenous agents may mitigate the risks of neurotoxicity. This approach may be performed safely in some patients and can be considered as an option in selected short procedures.

CONCLUSION

There is no conclusive evidence that a single short anesthetic in infancy has a detectable neurodevelopmental effect. Data do not support waiting until later in childhood to perform general anesthesia for single short procedures. With the complexities and nuances of different anesthetic methods, patients and procedures, the planning and execution of anesthesia for the pediatric patient is generally best accomplished by an anesthesiologist, ideally a pediatric anesthesiologist.

TYPE OF STUDY

Systematic review of level 1-4 studies.

LEVEL OF EVIDENCE

Level 1-4 (mainly level 3-4).

Repeated Doses of Ketamine Affect the Infant Rat Urogenital System

Aim

Long-term ketamine use is known to create an interstitial cystitis-like problem in the bladder. It is known that long-term intermittent ketamine is applied to the children receiving radiotherapy for sedation. This study was planned to investigate whether this effect seen in the bladder causes similar changes in the kidneys, testicles, epididymis and ductus deferens.

Materials and Methods

A total of 12 male Wistar Albino rats for 3 weeks were used in the study. Rats were divided equally into 2 groups as, ketamine and saline. 50 mg/kg ketamine was administered intraperitoneally during 21 days to ketamine (K) groups. 1mL/kg saline was administered intraperitoneally during 21 days to saline (S) groups. At the end of 21 days kidney and testicular tissues were taken for biochemical and histopathological evaluations.

Results

Histological assessment of kidney tissue showed that tubule epithelial congestion increased significantly in the ketamine group. Epididymis congestion and distortion in the epididymal gland were found to be different in the ketamine group when testicular tissue was examined. Thiobarbituric acid reactive substances (TBARS) level in testicular and kidney tissue was found to be significantly higher in the ketamine group according to the saline group. Catalase (CAT) enzyme activity was significantly lower in the ketamine group compared to the saline group in both tissues. Paraoxonase-1 (PON-1) enzyme activity was significantly higher in the ketamine group compared to the saline group.

Conclusion

We think that the results we have achieved in this study will provide guidance on ketamine, which is repeated in daily anesthesia applications, especially in radiation oncology. But these findings should be supported by clinical and experimental studies that will be conducted in a more detailed and broad series.

Involvement of the ventral, but not dorsal, hippocampus in anxiety-like behaviors in mice exposed to the elevated plus maze: participation of CRF1 receptor and PKA pathway

BACKGROUND

The hippocampus is a limbic structure involved in anxiety-like behaviors. We aimed to evaluate the role of the dorsal (DH) and ventral (VH) hippocampus in anxiety-like behaviors in the elevated plus maze (EPM).

METHODS

We inhibited these brain regions using cobalt chloride (CoCl₂: 1.0 nmol) microinjections. We also investigated the involvement of corticotropin-releasing factor (CRF) action and protein kinase A (PKA) pathway using intra-DH and intra-VH microinjections of the CRF1 receptor antagonist CP376395 (0, 3.0, or 6.0 nmol) and the PKA inhibitor H-89 (0, 2.5, or 5.0 nmol).

RESULTS

The results indicated that intra-VH CoCl₂ microinjection increased the percentage of time spent and entries in the open arms. The mice also exhibited fewer stretch attend postures in the protected area and increased percentage of open arm entries. Further, intra-VH injection of 3.0 nmol CP376395 increased time spent in the open arms. Intra-DH injection of 6.0 nmol CP376395 increased the frequency of unprotected head dipping, whereas intra-VH injection of 6 nmol CP376395 increased the frequency of protected head dipping. Intra-VH, but not intra-DH, microinjection of 2.5 nmol H-89 increased the percentages of open arm entries and time spent in the open arms. Microinjection of 2.5 and 5.0 nmol H-89 reduced the frequency of protected head dipping behavior.

CONCLUSIONS

This study demonstrated that VH modulates anxiety-like behaviors in EPM. Moreover, CRF and the cAMP/PKA pathway seem to modulate these effects.

Effects of ketamine on neurogenesis, extracellular matrix homeostasis and proliferation in hypoxia-exposed HT22 murine hippocampal neurons

Ketamine is a widely used drug in pediatric anesthesia, and both neurotoxic and neuroprotective effects have been associated with its use. There are only a few studies to date which have examined the effects of ketamine on neurons under hypoxic conditions, which may lead to severe brain damage and poor neurocognitive outcomes in neonates. In the present study, the effects of ketamine on cellular pathways associated with neurogenesis, extracellular matrix homeostasis and proliferation were examined in vitro in hypoxia-exposed neurons. Differentiated HT22 murine hippocampal neurons were treated with 1, 10 and 20 µM ketamine and cultured under hypoxic or normoxic conditions for 24 h followed by quantitative PCR analysis of relevant candidate genes. Ketamine treatment did not exert any notable effects on the mRNA expression levels of markers of neurogenesis (neuronal growth factor and syndecan 1), extracellular matrix homeostasis (matrix-metalloproteinase 2 and 9, tenascin C and tenascin R) or proliferation markers (Ki67 and proliferating cell nuclear antigen) compared with the respective untreated controls. However, there was a tendency towards downregulation of multiple cellular markers under hypoxic conditions and simultaneous ketamine treatment. No dose-dependent association was found in the ketamine treated groups for genetic markers of neurogenesis, extracellular matrix homeostasis or proliferation. Based on the results, ketamine may have increased the vulnerability of hippocampal neurons in vitro to hypoxia, independent of the dose. The results of the present study contribute to the ongoing discussion on the safety concerns around ketamine use in pediatric clinical practice from a laboratory perspective.

Yes‑associated protein protects and rescues SH‑SY5Y cells from ketamine‑induced apoptosis

Ketamine is a widely used intravenous anesthetic; however, basic and clinical studies have demonstrated that prolonged exposure can cause irreversible injury to the immature human brain. Yes-associated protein (YAP) is the main effector of the Hippo signaling pathway, which serves an important role in regulating tissue homeostasis and organ size during development. However, whether YAP mediates ketamine-induced apoptosis is not completely understood. Based on the functions of YAP during apoptosis resistance and cell self-renewal regulation, the present study hypothesized that YAP serves a role during ketamine-induced apoptosis. An in vitro model was utilized to investigate the effects of ketamine on neurotoxicity and to further investigate the role of YAP in ketamine-induced apoptosis using techniques including CCK-8 assay, flow cytometry and western blotting. The present study assessed the effects of YAP overexpression and knockdown on the expression of typical apoptotic markers in SH-SY5Y cells. Ketamine induced apoptosis in a dose-dependent manner, which was regulated by YAP. Following YAP overexpression, ketamine-treated SH-SY5Y cells displayed increased activity and viability, whereas expression levels of the apoptotic markers were decreased compared with the negative control group. By contrast, ketamine-induced apoptosis was enhanced following YAP knockdown. Collectively, the results of the present study indicated that YAP may serve an important role during ketamine-induced neurotoxicity, and alterations to YAP signaling may counteract ketamine-induced apoptosis. The neuroprotective effect of YAP activation may serve as a novel pharmacological target for the treatment of ketamine-induced neurotoxicity via neurogenesis normalization.

Neonatal ketamine exposure-induced hippocampal neuroapoptosis in the developing brain impairs adult spatial learning ability

Ketamine exposure can lead to selective neuroapoptosis in the developing brain. p66ShcA, the cellular adapter protein expressed selectively in immature neurons, is a known pro-apoptotic molecule that triggers neuroapoptosis when activated. Sprague-Dawley rats at postnatal day 7 were subcutaneously injected in the neck with ketamine 20 mg/kg, six times at 2-hour intervals. At 0, 1, 3, and 6 hours after final injection, western blot assay was used to detect the expression of cleaved caspase-3, p66ShcA, and phosphorylated p66ShcA. We found that the expression of activated p66ShcA and caspase-3 increased after ketamine exposure and peaked at 3 hours. The same procedure was performed on a different group of rats. At the age of 4 weeks, spatial learning and memory abilities were tested with the Morris water maze. Latency to find the hidden platform for these rats was longer than it was for control rats, although the residence time in the target quadrant was similar. These findings indicate that ketamine exposure resulted in p66ShcA being activated in the course of an apoptotic cascade during the neonatal period. This may have contributed to the deficit in spatial learning and memory that persisted into adulthood. The experimental protocol was approved by the Institutional Animal Care and Use Committee at the University of Texas at Arlington, USA (approval No. A13.008) on January 22, 2013.

Comparison of total cost and outcomes between single-stage open reduction and Pemberton periacetabular osteotomy operation and two separate consecutive operations in treatment of bilateral developmental hip dysplasia in children at walking age

Open reduction and Pemberton periacetabular osteotomy (PPO) is one of the most preferred techniques for the treatment of developmental hip dyslaplasia (DDH) after the walking age. Performing the surgery as a one-stage operation or two separate consecutive operations is a controversial issue. In this study, we aimed to compare the outcomes, length of hospitalization and total cost between the patients whom had single-stage open reduction and PPO or two consecutive operations due to bilateral DDH in the walking age children. One hundred thirty patients with bilateral DDH had undergone open reduction and PPO for both hips. Seventy-five patients had one-stage open reduction and PPO for both of the hips, whereas 55 patients have two separate consecutive operations. Total time of exposure to anesthetics, blood loss and duration of operation were noted. Hospitalization period and total treatment costs were also noted for each patient. There was no statistically significant difference between the groups regarding the preoperative and postoperative AIs (P > 0.05). Comparing the total cost, length of hospitalization, exposure to anesthetics, perioperative blood loss, there was statistically significant difference between the groups (P < 0.005). Single-stage surgery had favorable outcomes. Major benefits of single-stage surgery for treatment of bilateral DDH are the reduced costs, anesthesia duration, intraoperative blood loss and hospitalization period. Also it can be presumed that prolonged immobilization can lead to loss of bone strength and resulting in fragility fractures. So single-stage open reduction and PPO for bilateral DDH can be preferred in experienced clinics.

Behavioral Changes and Neuronal Damage in Rhesus Monkeys after 10 Weeks of Ketamine Administration Involve Prefrontal Cortex Dopamine D2 Receptor and Dopamine Transporter

The dopamine D2 receptor (DRD2) and dopamine transporter (DAT) play a regulatory role in dopaminergic neurotransmission and thus play an important role in drug addiction. The prefrontal cortex (PFC), a critical part of the mesencephalic dopaminergic system, is thought to be involved in the development and maintenance of drug addiction. The addiction to ketamine is thought to induce behavioral effects primarily through actions on the central nervous system. However, the neural mechanism underlying the effects of ketamine addiction remains unclear. In this study, we investigate the involvement of PFC DRD2 and DAT in ketamine addiction effects after ketamine administration for 10 weeks in nonhuman primates. To this end, after administering ketamine to rhesus monkeys for 10 weeks, we assessed changes in body weight and behavior. Additionally, neuronal changes in the PFC were examined by hematoxylin and eosin (HE) staining; the DRD2 and DAT mRNA and protein expression levels in the PFC were determined by real-time PCR and Western blot analysis, respectively. After 10-week ketamine administration, the assessment of the manifestations of toxicity in rhesus monkeys revealed significant changes in body weight and behavior, decreased DRD2 and DAT mRNA and protein expression in the PFC, and histological abnormalities including neuronal eosinophilia, pyknosis and disorderly arrangement of neurons in the PFC. These results suggest that the reduced expression of DRD2 and DAT in PFC could be involved in the behavioral and the neurological changes induced by ketamine administration, which may play an important role in the molecular mechanisms of ketamine addiction.

SmartTots Outcomes Workshop 2017: Notes From a Round Table Discussion About Outcome Measures

An important element of designing research studies is the selection of appropriate outcome measures to ensure that the question posed is properly answered given the evidence. The selection of outcome measures is especially important when tackling complex, interdisciplinary problems, where appropriate outcome measures may not be as simple as a blood test or a laboratory value. One such area of study is the research into neurodevelopmental outcomes after early exposure to anesthetic agents. Concern has arisen recently that certain anesthetic agents may be toxic to the developing brain; a public-private partnership, SmartTots, was formed in conjunction with the Food and Drug Administration and various stakeholders to develop safe anesthetic regimens for neonates and infants who require surgery. However, as research has progressed, questions have arisen regarding the best outcome measures to use in order to detect a true effect, as well as the optimal window in which to measure. These issues were discussed in a round table meeting during the SmartTots meeting in September 2017, and a summary of the discussion is presented here.

Spinal anesthesia in children: most pediatric urologists are not on board

OBJECTIVE

In 2016, the Food and Drug Administration issued a warning on general anesthetic medications used for lengthy procedures (>3 h) in children younger than 3 years. Spinal anesthesia can be a safe alternative to general anesthesia for many pediatric urology procedures. It can shorten total operating room (OR) time, provide excellent pain control, and allow parents to reunite with their child immediately after surgery. However, use of spinal anesthesia can also directly affect the operating surgeon (awake patient, time constraints of spinal, and prolonged preoperative time). Members of the Societies for Pediatric Urology (SPU) and European Society of Pediatric Urology (ESPU) were surveyed to get their opinions on the use of spinal anesthesia for routine pediatric urology procedures. It was hypothesized that half of pediatric urologists would favor spinal anesthesia and that SPU members would be more likely to favor spinal anesthesia than their European colleagues.

MATERIALS AND METHODS

A short survey with five clinical scenarios was created. Scenarios assessed physicians' recommendations regarding timing and the type of anesthesia (general or spinal) for common pediatric urology procedures: undescended testicle, inguinal hernia, hypospadias, phimosis, and phimosis with penoscrotal webbing. Surveys were emailed to members of the SPU and ESPU. Responses and demographic information were collected and analyzed.

RESULTS

The survey was completed by 113 SPU members (46% response rate for members who opened the invitation) and 109 ESPU members. For all clinical scenarios, < 20% of pediatric urologists from the SPU and <25% from the ESPU favor doing any procedure with spinal anesthesia. The majority of respondents practice in children's hospitals with pediatric anesthesiologists, but roughly half of the responders (54% SPU and 43% ESPU) do not think their anesthesia colleagues would be comfortable performing spinal anesthesia. Furthermore, only 51% of SPU and 36% of ESPU members discuss the possible neurodevelopmental side-effects of anesthesia with parents; similarly, less than half of all respondents think their anesthesia colleagues address these potential side-effects when obtaining consent. The only significant difference between SPU and ESPU responses was that ESPU members tended to delay penile surgery more than SPU respondents.

CONCLUSION

Whether general anesthesia has any effect on the developing brain of children undergoing routine pediatric urology procedures is unclear. Yet, few pediatric urologists, independent of their region of practice, prefer spinal to general anesthesia. Collaboration in the OR is the key to success, and it is important that pediatric urologists and pediatric anesthesiologists work together to balance the benefits and risks of general and spinal anesthesia.

Expanding Role of NMDA Receptor Antagonists in the Management of Pain

Pain management is complex regardless of whether the pain is acute or chronic in nature or non-cancer or cancer related. In addition, relatively few pain pharmacotherapy options with adequate efficacy and safety data currently exist. Consequently, interest in the role of NMDA receptor antagonists as a pharmacological pain management strategy has surfaced. This narrative review provides an overview of the NMDA receptor and elaborates on the pharmacotherapeutic profile and pain management literature findings for the following NMDA receptor antagonists: ketamine, memantine, dextromethorphan, and magnesium. The literature on this topic is characterized by small studies, many of which exhibit methodological flaws. To date, ketamine is the most studied NMDA receptor antagonist for both acute and chronic pain management. Although further research about NMDA receptor antagonists for analgesia is needed and the optimal dosage/administration regimens for these drugs have yet to be determined, ketamine appears to hold the most promise and may be of particular value in the perioperative pain management realm.

Ketamine exacerbates cortical neuroapoptosis under hyperoxic conditions by upregulating expression of the N-methyl-D-aspartate receptor subunit NR1 in the developing rat brain

BACKGROUND

Ketamine and hyperoxia are widely used in obstetric and pediatric settings. Either ketamine or hyperoxia has been reported to cause neuroapoptosis in the developing brain, and ketamine-induced neuronal apoptosis may involve a compensatory upregulation of the N-methyl-D-aspartate (NMDA) receptor NR1 subunit. This study investigated the impact of ketamine administration under hyperoxic conditions on cortical neuroapoptosis and NR1 subunit expression in the infant rat brain.

METHODS

Male, 7-day-old rats were randomly allocated to four groups: control, ketamine, hyperoxia, and ketamine + hyperoxia (n = 18 per group). Rats in the control and ketamine groups received subcutaneous injections of either vehicle (saline) or ketamine (50 mg/kg) in room air (21% oxygen). The hyperoxia and ketamine + hyperoxia groups were exposed to 60% oxygen for 2 h after receiving saline or ketamine. Physiological parameters and arterial oxygen saturation were observed. Neuronal apoptosis and the expressions of NR1 mRNA and protein in the frontal cortex were also examined by transferase dUTP nick end labeling (TUNEL) assays, qPCR and Western blot, respectively.

RESULTS

Ketamine alone had no effect on paO₂ (P > 0.05)_, but pups exposed to hyperoxia or hyperoxia + ketamine had significantly greater paO₂ values compared to control animals (P < 0.01). Animals exposed to ketamine and ketamine + hyperoxia showed higher apoptotic scores, mRNA and protein expression levels of NR1 than control animals (P < 0.01), and ketamine + hyperoxia caused a significantly greater increase than ketamine alone (P < 0.01).

CONCLUSIONS

These data suggest that ketamine administration under hyperoxic conditions exacerbates cortical neuroapoptosis in the developing brain, which may be closely associated with an enhancement in NMDA receptor NR1 subunit expression.

KIF17 mediates the learning and memory impairment in offspring induced by maternal exposure to propofol during middle pregnancy

Preclinical studies suggest that propofol may cause neuronal injury to the developing brain. A previous study demonstrated that, in a rat model, maternal exposure to propofol during early or late pregnancy caused learning and memory impairment in the offspring. However, whether propofol exposure during middle pregnancy can cause long‑term behavioral deficits in the offspring remains to be elucidated. N‑methyl‑D‑aspartate receptor 2B subunit (NR2B) serves a critical role in memory modulation. To exert its function, NR2B must be transported to the neuronal membrane by kinesin family member 17 (KIF17). The aim of the present study was to investigate the role of KIF17 in learning and memory impairment in rat offspring caused by propofol exposure during middle pregnancy. Pregnant rats were exposed to propofol on gestational day 14 (G14) for 4 and 8 h, with control pregnant rats receiving an equal volume of normal saline. The learning and memory of the offspring was assessed using Morris water maze tests from postnatal day 30 (P30) to P36. The levels of KIF17 protein, total NR2B (T‑NR2B) and membrane NR2B (M‑NR2B) in the hippocampus were detected using western blotting. The results demonstrated that propofol exposure caused learning and memory deficits and decreased KIF17 and M‑NR2B protein levels in the hippocampus; however, no but changes in the expression of T‑NR2B were observed. These results indicate that maternal propofol exposure during middle pregnancy impairs learning and memory in offspring rats by suppressing the expression of KIF17 and inhibiting the translocation of NR2B to the neuronal membrane.

Severe bilateral cerebellar edema from ingestion of ketamine: case report

The use of ketamine as a drug of abuse has increased and so too has the risk of accidental overdose. Here, the authors report the case of a 10-month-old infant who inadvertently ingested ketamine. The child demonstrated severe cerebellar swelling that required emergency surgical intervention. The authors describe the clinical course of this child and present the radiographic characteristics of the brain. The imaging characteristics were not consistent with purely anoxic injury, thus suggesting a specific effect of this drug. To the authors' knowledge, similar imaging characteristics in this context have not been described.

Molecular Mechanisms of Anesthetic Neurotoxicity: A Review of the Current Literature

Data from epidemiologic studies and animal models have raised a concern that exposure to anesthetic agents during early postnatal life may cause lasting impairments in cognitive function. It is hypothesized that this is due to disruptions in brain development, but the mechanism underlying this toxic effect remains unknown. Ongoing research, particularly in rodents, has begun to address this question. In this review we examine currently postulated molecular mechanisms of anesthetic toxicity in the developing brain, including effects on cell death pathways, growth factor signaling systems, NMDA and GABA receptors, mitochondria, and epigenetic factors. The level of evidence for each putative mechanism is critically evaluated, and we attempt to draw connections between them where it is possible to do so. Although there are many promising avenues of research, at this time no consensus can be reached as to a definitive mechanism of injury.

Prolonged ketamine exposure induces increased activity of the GluN2B-containing N-methyl-d-aspartate receptor in the anterior cingulate cortex of neonatal rats

Ketamine is a commonly used anesthetic among pediatric patients due to its high efficacy. However, it has been demonstrated by several preclinical studies that, widespread accelerated programmed death of neurons (neuroapoptosis) occurs due to prolonged or repeated exposure to ketamine specifically in the neonatal brain. Therefore, an emphasis on understanding the molecular mechanisms underlying this selective vulnerability of the neonatal brain to ketamine-induced neuroapoptosis becomes important in order to identify potential therapeutic targets, which would help prevent or at least ameliorate this neuroapoptosis. In this study, we demonstrated that repeated ketamine administration (6 injections of 20mg/kg dose given over 12h time period) in neonatal (postnatal day 7; PND 7) Sprague-Dawley rats induced a progressive increase in N-methyl-d-aspartate receptor (NMDAR)-mediated excitatory postsynaptic currents (EPSCs) in the neurons of the anterior cingulate cortex (ACC) for up to 6h after the last ketamine dose. Specifically, we observed that the increased EPSCs were largely mediated by GluN2B-containing NMDARs in the neurons of the ACC. Along with increased synaptic transmission, there was also a significant increase in the expression of the GluN2B-containing NMDARs as well. Taken together, these results showed that after repeated exposure to ketamine, the synaptic transmission mediated by GluN2B-containing NMDARs was significantly increased in the neonatal brain. This was significant as it showed for the first time that ketamine had subunit-specific effects on GluN2B-containing NMDARs, potentially implicating the involvement of these subunits in the increased vulnerability of immature neurons of the neonatal brain to ketamine-induced neuroapoptosis.

A holistic approach to anesthesia-induced neurotoxicity and its implications for future mechanistic studies

The year 2016 marked the 15th anniversary since anesthesia-induced developmental neurotoxicity and its resulting cognitive dysfunction were first described. Since that time, multiple scientific studies have supported these original findings and investigated possible mechanisms behind anesthesia-induced neurotoxicity. This paper reviews the existing mechanistic literature on anesthesia-induced neurotoxicity in the context of a holistic approach that emphasizes the importance of both neuronal and non-neuronal cells during early postnatal development. Sections are divided into key stages in early neural development; apoptosis, neurogenesis, migration, differentiation, synaptogenesis, gliogenesis, myelination and blood brain barrier/cerebrovasculature. In addition, the authors combine the established literature in the field of anesthesia-induced neurotoxicity with literature from other related scientific fields to speculate on the potential role of non-neuronal cells and to generate new future hypotheses for understanding anesthetic toxicity and its application to the practice of pediatric anesthesia.

Protective Effect of Minocycline Against Ketamine-Induced Injury in Neural Stem Cell: Involvement of PI3K/Akt and Gsk-3 Beta Pathway

It has been suggested that ketamine cause injury during developing brain. Minocycline (MC) could prevent neuronal cell death through the activation of cell survival signals and the inhibition of apoptotic signals in models of neurodegenerative diseases. Here we investigated the protective effect of MC against ketamine-induced injury in neural stem cells (NSCs) from neonatal rat. Ketamine (100 μM/L) significantly inhibited NSC proliferation, promoted their differentiation into astrocytes and suppressed neuronal differentiation of NSCs. Moreover, the apoptotic level was increased following ketamine exposure. MC pretreatment greatly enhanced cell viability, decreased caspase-3-like activity, even reversed the differentiation changes caused by ketamine. To elucidate a possible mechanism of MC' neuroprotective effect, we investigated the phosphatidylinositol 3-kinase (PI3K) pathway using LY294002, a specific PI3K inhibitor. Immunoblotting revealed that MC enhanced the phosphorylation/activation of Akt and phosphorylation/inactivation of glycogen synthase kinase-3beta (Gsk-3β). Our results suggest that PI3K/Akt and Gsk-3β pathway are involved in the neuroprotective effect of MC.

Anesthetic neurotoxicity: Apoptosis and autophagic cell death mediated by calcium dysregulation

A number of findings suggested that general anesthetics induced neural cell death by apoptosis in various animal models. Although clinical evidence regarding the correlation between anesthetic exposures at young age and subsequent cognitive impairments remains unclear, repeated or consistent exposures to general anesthetics may be a potential harmful risk in developing human brains. The mechanisms underlying the anesthetic neurotoxicity have received extensive attention recently. We will attempt a brief review to summarize current understanding on the role of both apoptosis and autophagic cell death mediated by calcium dysregulation in anesthetic neurotoxicity.

Minimally invasive biomarkers of general anesthetic-induced developmental neurotoxicity

The association of general anesthesia with developmental neurotoxicity, while nearly impossible to study in pediatric populations, is clearly demonstrable in a variety of animal models from rodents to nonhuman primates. Nearly all general anesthetics tested have been shown to cause abnormal brain cell death in animals when administered during periods of rapid brain growth. The ability to repeatedly assess in the same subjects adverse effects induced by general anesthetics provides significant power to address the time course of important events associated with exposures. Minimally-invasive procedures provide the opportunity to bridge the preclinical/clinical gap by providing the means to more easily translate findings from the animal laboratory to the human clinic. Positron Emission Tomography or PET is a tool with great promise for realizing this goal. PET for small animals (microPET) is providing valuable data on the life cycle of general anesthetic induced neurotoxicity. PET radioligands (annexin V and DFNSH) targeting apoptotic processes have demonstrated that a single bout of general anesthesia effected during a vulnerable period of CNS development can result in prolonged apoptotic signals lasting for several weeks in the rat. A marker of cellular proliferation (FLT) has demonstrated in rodents that general anesthesia-induced inhibition of neural progenitor cell proliferation is evident when assessed a full 2weeks after exposure. Activated glia express Translocator Protein (TSPO) which can be used as a marker of presumed neuroinflammatory processes and a PET ligand for the TSPO (FEPPA) has been used to track this process in both rat and nonhuman primate models. It has been shown that single bouts of general anesthesia can result in elevated TSPO expression lasting for over a week. These examples demonstrate the utility of specific PET tracers to inform, in a minimally-invasive fashion, processes associated with general anesthesia-induced developmental neurotoxicity. The fact that PET procedures are also used clinically suggests an opportunity to confirm in humans what has been repeatedly observed in animals.

Drug induced mitochondrial dysfunction: Mechanisms and adverse clinical consequences

Several commonly used medications impair mitochondrial function resulting in adverse effects or toxicities. Drug induced mitochondrial dysfunction may be a consequence of increased production of reactive oxygen species, altered mitochondrial permeability transition, impaired mitochondrial respiration, mitochondrial DNA damage or inhibition of beta-oxidation of fatty acids. The clinical manifestation depends on the specific drug and its effect on mitochondria. Given the ubiquitous presence of mitochondria and its central role in cellular metabolism, drug-mitochondrial interactions may manifest clinically as hepatotoxicity, enteropathy, myelosuppression, lipodystrophy syndrome or neuropsychiatric adverse effects, to name a few. The current review focuses on specific drug groups which adversely affect mitochondria, the mechanisms involved and the clinical consequences based on the data available from experimental and clinical studies. Knowledge of these adverse drug-mitochondrial interactions may help the clinicians foresee potential issues in individual patients, prevent adverse drug reactions or alter drug regimens to enhance patient safety.

Evaluating the control: minipump implantation and breathing behavior in the neonatal rat

We evaluated genioglossus (GG) gross motoneuron morphology, electromyographic (EMG) activities, and respiratory patterning in rat pups allowed to develop without interference (unexposed) and pups born to dams subjected to osmotic minipump implantation in utero (saline-exposed). In experiment 1, 48 Sprague-Dawley rat pups (Charles-River Laboratories), ages postnatal day 7 (P7) through postnatal day 10 (P10), were drawn from two experimental groups, saline-exposed (n = 24) and unexposed (n = 24), and studied on P7, P8, P9, or P10. Pups in both groups were sedated (Inactin hydrate, 70 mg/kg), and fine-wire electrodes were inserted into the GG muscle of the tongue and intercostal muscles to record EMG activities during breathing in air and at three levels of normoxic hypercapnia [inspired CO2 fraction (FiCO2 ): 0.03, 0.06, and 0.09]. Using this approach, we assessed breathing frequency, heart rate, apnea type, respiratory event types, and respiratory stability. In experiment 2, 16 rat pups were drawn from the same experimental groups, saline-exposed (n = 9) and unexposed (n = 7), and used in motoneuron-labeling studies. In these pups a retrograde dye was injected into the GG muscle, and the brain stems were subsequently harvested and sliced. Labeled GG motoneurons were identified with microscopy, impaled, and filled with Lucifer yellow. Double-labeled motoneurons were reconstructed, and the number of primary projections and soma volumes were calculated. Whereas pups in each group exhibited the same number (P = 0.226) and duration (P = 0.093) of respiratory event types and comparable motoneuron morphologies, pups in the implant group exhibited more central apneas and respiratory instability relative to pups allowed to develop without interference.

Etomidate exposure in early infant mice (P10) does not induce apoptosis or affect behaviour

BACKGROUND

Numerous animal studies have shown that all commonly used intravenous anaesthetic drugs and volatile agents may cause neuronal apoptosis following exposure in early life. Most studies have focussed on detecting increased apoptosis but their methods are not always readily transferrable to humans. The lipid formulation of etomidate represents an alternative to the currently established intravenous anaesthetic agents but there is no animal or human data on apoptosis or long-term behavioural changes. The aim of our study was to investigate the effects of etomidate on cerebral neuronal apoptosis and long-term behavioural effects using an established mouse model that represents the clinically relevant period of anaesthesia during early infancy in humans.

METHODS

Six groups of 10 day old mice (P10) were injected with either etomidate 0.3, 3 or 10 mg/kg, propofol 60 mg/kg, ketamine 50 mg/kg or placebo only. Apoptosis in the cerebral cortex and hippocampus was assessed 24 h after treatment (activated caspase-3). Late behavioural effects were tested at 2 months of age (spontaneous activity in a new environment).

RESULTS

No evidence was found of differences in activated caspase 3-concentrations among the study groups. Significant late behavioural changes were only observed in the ketamine group.

CONCLUSION

A single dose of etomidate in early infant mice at P10 did not produce evidence of cerebral apoptosis or impaired adult motor behaviour.

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.

The role of TNF-α in regulating ketamine-induced hippocampal neurotoxicity

INTRODUCTION

Ketamine is commonly used in pediatric anesthesia but recent studies have shown that it could induce neurotoxicity in the developing brain. The inflammatory cytokine, tumor necrosis factor α (TNF-α) is involved in the pathogenesis of various types of neurodegenerations. In the present study, we examined whether TNF-α may regulate ketamine-induced neurotoxicity in the hippocampus of neonatal mouse.

MATERIAL AND METHODS

The in vitro organotypic culture of hippocampal slices was used to investigate the gain-of-function and loss-of-function effect of TNF-α modulation on ketamine-induced hippocampal neurotoxicity. Also, western blotting analysis was used to examine the relative pathways associated with TNF-α modulation. In the in vivo Morris water maze test, TNF-α was genetically silenced to see if memory function was improved after anesthesia-induced memory impairment.

RESULTS

In in vitro experiments, adding TNF-α enhanced (112.99 ±5.4%, p = 0.015), whereas knocking down TNF-α ameliorated (46.8 ±11.6%, p = 0.003) ketamine-induced apoptosis in hippocampal CA1 neurons in the organotypic culture. Western blotting showed that addition of TNF-α reduced (67.1 ±3.7%, p = 0.022), whereas downregulation of TNF-α increased (126.87 ±8.5%, p = 0.004) the phosphorylation of PKC-ERK pathway in ketamine-treated hippocampus. In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.

CONCLUSIONS

Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity. This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.

Role of miR-34c in ketamine-induced neurotoxicity in neonatal mice hippocampus

Ketamine is a commonly used pediatric anesthetic, but it might affect development, or even induce neurotoxicity in the neonatal brain. We have used an in vivo neonatal mouse model to induce ketamine-related neurotoxicity in the hippocampus, and found that miR-34c, a microRNA associated with pathogenesis of Alzheimer's disease, was significantly upregulated during ketamine-induced hippocampal neurodegeneration. Functional assay of silencing miR-34c demonstrated that downregulation of miR-34c activated PKC-ERK pathway, upregulated anti-apoptotic protein BCL2, and ameliorated ketamine-induced apoptosis in the hippocampus. Cognitive examination with the Morris water maze test showed that ketamine-induced memory impairment was significantly improved by miR-34c downregulation. Thus, miR-34c is important in regulating ketamine-induced neurotoxicity in hippocampus.

Repeated dose of ketamine effect to the rat hippocampus tissue

AIM

We aimed to determine the neurotoxic effect of repeated ketamine administration on brain tissue and if neurotoxic effect was present, whether this effect continued 16 days later using histological stereological method, a quantitative and objective method.

MATERIALS AND METHODS

Female rats were divided into three groups, each containing five rats. Rats in Group I were given 0.9% saline solution 4 times a day for 5 days. The rats in Groups II and III were given ketamine as intraperitoneal injections. Rats in Groups I and II were sacrificed on 5(th) day while the ones in Group III on 21(st) day. Cornu ammonis (CA) and gyrus dentatus (GD) regions in hippocampus tissue of rats were studied using optic fractionation method.

FINDINGS

There were significantly less number of cells in hippocampal CA and GD regions of rats from Groups II and III compared to the ones from Group I. Difference in cell number was also significantly higher in Group III than in Group II, but this difference was not as pronounced as the one between Groups III and I.

CONCLUSION

Repeated ketamine doses caused neurotoxicity in rat hippocampus.

Repeated neonatal propofol administration induces sex-dependent long-term impairments on spatial and recognition memory in rats

Propofol is an anesthetic agent that gained wide use because of its fast induction of anesthesia and rapid recovery post-anesthesia. However, previous studies have reported immediate neurodegeneration and long-term impairment in spatial learning and memory from repeated neonatal propofol administration in animals. Yet, none of those studies has explored the sex-specific long-term physical changes and behavioral alterations such as social (sociability and social preference), emotional (anxiety), and other cognitive functions (spatial working, recognition, and avoidance memory) after neonatal propofol treatment. Seven-day-old Wistar-Kyoto (WKY) rats underwent repeated daily intraperitoneal injections of propofol or normal saline for 7 days. Starting fourth week of age and onwards, rats were subjected to behavior tests including open-field, elevated-plus-maze, Y-maze, 3-chamber social interaction, novel-object-recognition, passive-avoidance, and rotarod. Rats were sacrificed at 9 weeks and hippocampal protein expressions were analyzed by Western blot. Results revealed long-term body weight gain alterations in the growing rats and sex-specific impairments in spatial (female) and recognition (male) learning and memory paradigms. A markedly decreased expression of hippocampal NMDA receptor GluN1 subunit in female- and increased expression of AMPA GluR1 subunit protein expression in male rats were also found. Other aspects of behaviors such as locomotor activity and coordination, anxiety, sociability, social preference and avoidance learning and memory were not generally affected. These results suggest that neonatal repeated propofol administration disrupts normal growth and some aspects of neurodevelopment in rats in a sex-specific manner.

Neurodevelopmental implications of the general anesthesia in neonate and infants

Each year, about six million children, including 1.5 million infants, in the United States undergo surgery with general anesthesia, often requiring repeated exposures. However, a crucial question remains of whether neonatal anesthetics are safe for the developing central nervous system (CNS). General anesthesia encompasses the administration of agents that induce analgesic, sedative, and muscle relaxant effects. Although the mechanisms of action of general anesthetics are still not completely understood, recent data have suggested that anesthetics primarily modulate two major neurotransmitter receptor groups, either by inhibiting N-methyl-D-aspartate (NMDA) receptors, or conversely by activating γ-aminobutyric acid (GABA) receptors. Both of these mechanisms result in the same effect of inhibiting excitatory activity of neurons. In developing brains, which are more sensitive to disruptions in activity-dependent plasticity, this transient inhibition may have longterm neurodevelopmental consequences. Accumulating reports from preclinical studies show that anesthetics in neonates cause cellular toxicity including apoptosis and neurodegeneration in the developing brain. Importantly, animal and clinical studies indicate that exposure to general anesthetics may affect CNS development, resulting in long-lasting cognitive and behavioral deficiencies, such as learning and memory deficits, as well as abnormalities in social memory and social activity. While the casual relationship between cellular toxicity and neurological impairments is still not clear, recent reports in animal experiments showed that anesthetics in neonates can affect neurogenesis, which could be a possible mechanism underlying the chronic effect of anesthetics. Understanding the cellular and molecular mechanisms of anesthetic effects will help to define the scope of the problem in humans and may lead to preventive and therapeutic strategies. Therefore, in this review, we summarize the current evidence on neonatal anesthetic effects in the developmental CNS and discuss how factors influencing these processes can be translated into new therapeutic strategies.

The role of miR-124 in modulating hippocampal neurotoxicity induced by ketamine anesthesia

PURPOSE

Ketamine is widely used in pediatric anesthesia. Recent studies have demonstrated that excessive application of ketamine leads to cortical neurodegeneration in neonatal brains. The present study aims to characterize the functional role of neuronal microRNA, miR-124, in regulating ketamine-induced neurotoxicity in mouse hippocampus.

METHODS

Real-time quantitative PCR (RT-PCR) was used to examine the effect of high-dosage ketamine on the expression of miR-124 in murine hippocampus in vitro. Downregulation of hippocampal miR-124 was achieved by lentivirual transfection, and its effects on protecting ketamine-induced hippocampal neurodegeneration were examined both in vitro and in vivo.

RESULTS

Hippocampal miR-124 was upregulated by ketamine treatment. Knocking down miR-124 in vitro reduced ketamine-induced apoptosis in hippocampal CA1 neurons, upregulated AMPA receptors phosphorylation and activated the protein kinase C/extracellular signal-regulated kinases (PKC/ERK) pathway. In the in vivo Morris water maze test, following ketamine-induced hippocampal neurodegeneration, mice subjected to hippocampal miR-124 inhibition showed improved memory performance.

CONCLUSIONS

Our study demonstrated that miR-124 played an important role in regulating ketamine-induced hippocampal neurodegeneration. Inhibiting miR-124 may provide a molecular target to improve memory performance in both human and animals suffering from overanesthetizing-related neurotoxicity.

Repeated exposure to anesthetic ketamine can negatively impact neurodevelopment in infants: a prospective preliminary clinical study

Animal experiments indicate that repeated exposure to ketamine adversely affects the developing brain. Whether it has the same effect on infants remains unclear. We recruited infants who were scheduled for 1 to 3 outpatient laser surgery treatments of benign facial growths with ketamine anesthesia. Patients were assigned to the Ket(1), Ket(2), or Ket(3) group, according to the number of treatments. The Bayley Scales of Infant Development-Second Edition (BSID-II) was used to assess neurodevelopmental outcomes before the first and after the last therapy. Levels of S-100β were also measured. Bayley Scales of Infant Development-Second Edition scores after the last procedure were lower than those before the first surgery in the Ket(3) group (P < .05). S-100β levels after the last procedure were significantly higher than those before the first surgery in all groups (P < .05). Our results suggest that 3 or more exposures to anesthetic ketamine have the potential to adversely affect neurodevelopment in infants.

17β-estradiol attenuates ketamine-induced neuroapoptosis and persistent cognitive deficits in the developing brain

Previous studies have demonstrated that the commonly used anesthetic ketamine can induce widespread neuroapoptosis in the neonatal brain and can cause persistent cognitive impairments as the animal matures. Therefore, searching for adjunctive neuroprotective strategies that inhibit ketamine-induced neuroapoptosis and persistent cognitive impairments is highly warranted. The primary goal of this study was to investigate the protective effect of 17β-estradiol against ketamine-induced neuroapoptosis and persistent cognitive impairments in adult rats. Starting from postnatal day 7, Sprague-Dawley male rat pups were given a daily administration of ketamine (75mg/kg, i.p.) or 17β-estradiol (600μg/kg, s.c.) in combination with ketamine (75mg/kg, i.p.). The animals were treated for three consecutive days. 24h after the last injection, the rats were decapitated, and the prefrontal cortex (PFC) was isolated to detect neuroapoptosis by cleaved caspase-3 immunohistochemistry and by using the TUNEL assay. The neuroactive steroid 17β-estradiol was quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The protein levels of BDNF and pAkt were measured by western blot analysis. At two months of age (60 days), the learning and memory abilities were tested using the Morris water maze. The results showed that ketamine triggered significant neuroapoptosis in the neonatal PFC accompanied by the downregulation of 17β-estradiol, BDNF and pAkt. The co-administration of 17β-estradiol with ketamine attenuated these changes. Moreover, 17β-estradiol significantly reversed the learning and memory deficits observed at 60 days of age. In brief, our present data demonstrate that 17β-estradiol attenuates ketamine-induced neuroapoptosis and reverses long-term cognitive deficits in developing rats and thus may be a potential therapeutic and neuroprotective method for the treatment of neurodevelopmental disorders. This article is part of a Special Issue entitled SI: Brain and Memory.