The effect of prolonged anesthesia with isoflurane, propofol, dexmedetomidine, or ketamine on neural cell proliferation in the adult rat

Neobaicalein prevents isoflurane anesthesia-induced cognitive impairment in neonatal mice via regulating CREB1

OBJECTIVES

Isoflurane (ISO) is widely used in the clinic and research. The authors aimed to explore whether Neobaicalein (Neob) could protect neonatal mice from ISO-induced cognitive damage.

METHOD

The open field test, Morris water maze test, and tail suspension test was performed to assess the cognitive function in mice. Enzyme-linked immunosorbent assay was used to evaluate inflammatory-related protein concentrations. Immunohistochemistry was used to assess Ionized calcium-Binding Adapter molecule-1 (IBA-1) expression. Hippocampal neuron viability was detected using the Cell Counting Kit-8 assay. Double immunofluorescence staining was employed to confirm the interaction between proteins. Western blotting was used to assess protein expression levels.

RESULTS

Neob notably improved cognitive function and exhibited anti-inflammatory effects; moreover, under iso-treatment, it exhibited neuroprotective effects. Furthermore, Neob suppressed interleukin-1β, tumor necrosis factor-α, and interleukin-6 levels and upregulated interleukin-10 levels in ISO-treated mice. Neob significantly mitigated iso-induced increases in IBA-1-positive cell numbers of the hippocampus in neonatal mice. Furthermore, it inhibited ISO-induced neuronal apoptosis. Mechanistically, Neob was observed to upregulate cAMP Response Element Binding protein (CREB1) phosphorylation and protected hippocampal neurons from ISO-mediated apoptosis. Moreover, it rescued ISO-induced abnormalities of synaptic protein.

CONCLUSIONS

Neob prevented ISO anesthesia-induced cognitive impairment by suppressing apoptosis and inflammation through upregulating CREB1.

Effects of propofol on IGF-1 activity and cell behaviour in the GES 1 mucosal cell model

Propofol is an important and widely used anaesthetic drug in the clinic. Many works have shown that propofol has important biological functions except as an anaesthetic. In the current study, we mainly explored the effect of propofol on the biological activity of IGF-1, which is an important growth factor involved in regulating the growth and development of the stomach. Here, we explored the effect of propofol on the biological activity of IGF-1 in a GES-1-cell model. We found that propofol affected the biological activity of IGF-1. It not only reduces IGF-1/IGF-1R signalling but also changes IGF-1R cell characteristics. We further explored the mechanism by which propofol affected IGF-1 activity. Through a series of experiments, we found that propofol affected the stability of membrane-localised IGF-1R. It also affects the recycling of the IGF-1R receptor Propofol can affect the degradation of IGF-1R by changing the endocytosis of IGF-1R. In short, the current study found that propofol affected the biological activity of IGF-1, which laid the foundation for related research.

Is (R)-ketamine a Potential Therapeutic Agent for Treatment-Resistant Depression with Less Detrimental Side Effects? A Review of Molecular Mechanisms Underlying Ketamine and its Enantiomers

Approximately one-third of individuals with major depressive disorder are resistant to conventional antidepressants (i.e., monoamine-based therapies), and, even among respondents, a proper therapeutic effect may require weeks of treatment. Ketamine, a racemic mixture of the two enantiomers, (R)-ketamine and (S)-ketamine, is an N-methyl-d-aspartate receptor (NMDAR) antagonist and has been shown to have rapid-acting antidepressant properties in patients with treatment-resistant depression (TRD). Although (R)-ketamine has a lower affinity for NMDAR, it presents greater potency and longer-lasting antidepressant properties, with no major side effects, than racemic ketamine or (S)-ketamine in preclinical findings. Thereby, ketamine and its enantiomers have not only an antagonistic effect on NMDAR but also a strong synaptogenic-modulatory effect, which is impaired in TRD pathophysiology. In this review, we summarize the current evidence regarding the modulation of neurotransmission, neuroplasticity, and neural network activity as putative mechanisms of these rapid-acting antidepressants, highlighting differences on intracellular signaling pathways of synaptic proteins such as mammalian target of rapamycin (mTOR), extracellular signal-regulated kinase (ERK) and brain-derived neurotrophic factor (BDNF). In addition, we discuss probable mechanisms involved in the side effects of ketamine and its enantiomers.

Propofol Affects EGF's Activity in Intestinal Cell by Down-Regulating EGFR-Mediated Intracellular Signaling

Propofol is a commonly used anesthetic drug in clinic. In recent years, a series of non-anesthetic effects of propofol have been discovered. Studies have shown that propofol has many effects on the intestine. Epidermal growth factor (EGF) is one of the most important growth factors that could regulate intestinal growth and development. In the current study, we studied the effect of protocol on the biological activity of EGF on intestinal tissue and cell models. Through flow cytometry, indirect immunofluorescence and Western-blot and other technologies, it was found that propofol reduced the activity of EGF on intestinal cells, which inhibited EGF-induced intestinal cell proliferation and changed the cell behavior of EGF. To further explore the potential mechanism by which propofol down-regulated epidermal growth factor receptor (EGFR)-induced signaling, we carried out a series of related experiments, and found that propofol may inhibit the proliferation of intestinal cells by inhibiting the EGFR-mediated intracellular signaling pathway. The current research will lay the theoretical and experimental basis for further study of the effect of propofol on the intestine.

Histopathological study on neuroapoptotic alterations induced by etomidate in rat hippocampus

In human, there is substantial neurogenesis in the hippocampus that is implicated in memory formation and learning. These new-born neurons can be affected by neuropathological conditions. Anesthesia and surgical procedures are associated with postoperative cognitive changes particularly, impaired memory and learning. Therefore, the aim of this study was to evaluate the possible neurodegenerative effects of etomidate in rat hippocampus. Thirty male Wistar rats weighing 250 ± 30 g were randomly divided into 3 groups: 1) Etomidate group; four times 20 mg intraperitoneal injection with 1-h intervals, 2) Control group; the equal volume of normal saline, and 3) Normal group; without any intervention. 6 h after the last injection, the brains were removed and processed according to routine histological methods. TUNEL assay and toluidine blue staining were performed to evaluate neuro-histopathological changes in different regions of hippocampus. Our results showed that the number of TUNEL positive cells and dark neurons (DNs) in etomidate group were significantly higher in the CA1, CA2, CA3, and dentate gyrus (DG) of hippocampus compared with the control and normal groups (p < 0.05). While, there was no significant difference between the various regions of hippocampus in control and normal groups. Our findings showed that etomidate can increase apoptotic cells and dark neurons induction in different regions of hippocampus mainly in DG.

The neurotoxic effect of isoflurane on age-defined neurons generated from tertiary dentate matrix in mice

INTRODUCTION

Recent animal studies showed that isoflurane exposure may lead to the disturbance of hippocampal neurogenesis and later cognitive impairment. However, much less is known about the effect of isoflurane exposure on the neurons generated form tertiary dentate matrix, even though a great increase of granule cell population during the infantile period is principally derived from this area.

METHODS

To label the new cells originated from the tertiary dentate matrix, the mice were injected with BrdU on postnatal day 6 (P6). Then, the mice were exposed to isoflurane for 4 hr at 1, 8, 21, and 42 days after BrdU injection, and the brains were collected 24 hr later. The loss of newly generated cells/neurons with different developmental stage was assessed by BrdU, BrdU + DCX, BrdU + NeuN, or BrdU + Prox-1 staining, respectively.

RESULTS

We found that the isoflurane exposure significantly decreased the numbers of nascent cells (1 day old) and mature neurons (42 days old), but had no effect on the immature (8 days old) and early mature neurons (8 and 21 days old, respectively).

CONCLUSION

The results suggested isoflurane exposure exerts the neurotoxic effects on the tertiary dentate matrix-originated cells with an age-defined pattern in mice, which partly explain the cognitive impairment resulting from isoflurane exposure to the young brain.

The Effects of Anesthesia on Adult Hippocampal Neurogenesis

In animal studies, prolonged sedation with general anesthetics has resulted in cognitive impairments that can last for days to weeks after exposure. One mechanism by which anesthesia may impair cognition is by decreasing adult hippocampal neurogenesis. Several studies have seen a reduction in cell survival after anesthesia in rodents with most studies focusing on two particularly vulnerable age windows: the neonatal period and old age. However, the extent to which sedation affects neurogenesis in young adults remains unclear. Adult neurogenesis in the dentate gyrus (DG) was analyzed in male and female rats 24 h after a 4-h period of sedation with isoflurane, propofol, midazolam, or dexmedetomidine. Three different cell populations were quantified: cells that were 1 week or 1 month old, labeled with the permanent birthdate markers EdU or BrdU, respectively, and precursor cells, identified by their expression of the endogenous dividing cell marker proliferating cell nuclear antigen (PCNA) at the time of sacrifice. Midazolam and dexmedetomidine reduced cell proliferation in the adult DG in both sexes but had no effect on postmitotic cells. Propofol reduced the number of relatively mature, 28-day old, neurons specifically in female rats and had no effects on younger cells. Isoflurane had no detectable effects on any of the cell populations examined. These findings show no general effect of sedation on adult-born neurons but demonstrate that certain sedatives do have drug-specific and sex-specific effects. The impacts observed on different cell populations predict that any cognitive effects of these sedatives would likely occur at different times, with propofol producing a rapid but short-lived impairment and midazolam and dexmedetomidine altering cognition after a several week delay. Taken together, these studies lend support to the hypothesis that decreased neurogenesis in the young adult DG may mediate the effects of sedation on cognitive function.

Ketamine Alters Hippocampal Cell Proliferation and Improves Learning in Mice after Traumatic Brain Injury

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Traumatic brain injury induces cellular proliferation in the hippocampus, which generates new neurons and glial cells during recovery. This process is regulated by N-methyl-D-aspartate-type glutamate receptors, which are inhibited by ketamine. The authors hypothesized that ketamine treatment after traumatic brain injury would reduce hippocampal cell proliferation, leading to worse behavioral outcomes in mice.

METHODS

Traumatic brain injury was induced in mice using a controlled cortical impact injury, after which mice (N = 118) received either ketamine or vehicle systemically for 1 week. The authors utilized immunohistochemical assays to evaluate neuronal, astroglial, and microglial cell proliferation and survival 3 days, 2 weeks, and 6 weeks postintervention. The Morris water maze reversal task was used to assess cognitive recovery.

RESULTS

Ketamine dramatically increased microglial proliferation in the granule cell layer of the hippocampus 3 days after injury (injury + vehicle, 2,800 ± 2,700 cells/mm, n = 4; injury + ketamine, 11,200 ± 6,600 cells/mm, n = 6; P = 0.012). Ketamine treatment also prevented the production of astrocytes 2 weeks after injury (sham + vehicle, 2,400 ± 3,200 cells/mm, n = 13; injury + vehicle, 10,500 ± 11,300 cells/mm, n = 12; P = 0.013 vs. sham + vehicle; sham + ketamine, 3,500 ± 4,900 cells/mm, n = 14; injury + ketamine, 4,800 ± 3,000 cells/mm, n = 13; P = 0.955 vs. sham + ketamine). Independent of injury, ketamine temporarily reduced neurogenesis (vehicle-exposed, 105,100 ± 66,700, cells/mm, n = 25; ketamine-exposed, 74,300 ± 29,200 cells/mm, n = 27; P = 0.031). Ketamine administration improved performance in the Morris water maze reversal test after injury, but had no effect on performance in sham-treated mice.

CONCLUSIONS

Ketamine alters hippocampal cell proliferation after traumatic brain injury. Surprisingly, these changes were associated with improvement in a neurogenesis-related behavioral recall task, suggesting a possible benefit from ketamine administration after traumatic brain injury in mice. Future studies are needed to determine generalizability and mechanism.

Effects of Mild Blast Traumatic Brain Injury on Cerebral Vascular, Histopathological, and Behavioral Outcomes in Rats

To determine the effects of mild blast-induced traumatic brain injury (bTBI), several groups of rats were subjected to blast injury or sham injury in a compressed air-driven shock tube. The effects of bTBI on relative cerebral perfusion (laser Doppler flowmetry [LDF]), and mean arterial blood pressure (MAP) cerebral vascular resistance were measured for 2 h post-bTBI. Dilator responses to reduced intravascular pressure were measured in isolated middle cerebral arterial (MCA) segments, ex vivo, 30 and 60 min post-bTBI. Neuronal injury was assessed (Fluoro-Jade C [FJC]) 24 and 48 h post-bTBI. Neurological outcomes (beam balance and walking tests) and working memory (Morris water maze [MWM]) were assessed 2 weeks post-bTBI. Because impact TBI (i.e., non-blast TBI) is often associated with reduced cerebral perfusion and impaired cerebrovascular function in part because of the generation of reactive oxygen and nitrogen species such as peroxynitrite (ONOO-), the effects of the administration of the ONOO- scavenger, penicillamine methyl ester (PenME), on cerebral perfusion and cerebral vascular resistance were measured for 2 h post-bTBI. Mild bTBI resulted in reduced relative cerebral perfusion and MCA dilator responses to reduced intravascular pressure, increases in cerebral vascular resistance and in the numbers of FJC-positive cells in the brain, and significantly impaired working memory. PenME administration resulted in significant reductions in cerebral vascular resistance and a trend toward increased cerebral perfusion, suggesting that ONOO- may contribute to blast-induced cerebral vascular dysfunction.

Immunomodulation after ischemic stroke: potential mechanisms and implications for therapy

Brain injuries are often associated with intensive care admissions, and carry high morbidity and mortality rates. Ischemic stroke is one of the most frequent causes of injury to the central nervous system. It is now increasingly clear that human stroke causes multi-organ systemic disease. Brain inflammation may lead to opposing local and systemic effects. Suppression of systemic immunity by the nervous system could protect the brain from additional inflammatory damage; however, it may increase the susceptibility to infection. Pneumonia and urinary tract infection are the most common complications occurring in patients after stroke. The mechanisms involved in lung-brain interactions are still unknown, but some studies have suggested that inhibition of the cholinergic anti-inflammatory pathway and release of glucocorticoids, catecholamines, and damage-associated molecular patterns (DAMPs) are among the pathophysiological mechanisms involved in communication from the ischemic brain to the lungs after stroke. This review describes the modifications in local and systemic immunity that occur after stroke, outlines mechanisms of stroke-induced immunosuppression and their role in pneumonia, and highlights potential therapeutic targets to reduce post-stroke complications. Despite significant advances towards a better understanding of the pathophysiology of ischemic stroke-induced immunosuppression and stroke-associated pneumonia (SAP) in recent years, many unanswered questions remain. The true incidence and outcomes of SAP, especially in intensive care unit settings, have yet to be determined, as has the full extent of stroke-induced immunosuppression and its clinical implications.

Ketamine exposure during embryogenesis inhibits cellular proliferation in rat fetal cortical neurogenic regions

BACKGROUND

Developmental neurotoxicity of ketamine, an N-methyl-D-aspartate receptor antagonist, must be considered due to its widespread uses for sedation/analgesia/anesthesia in pediatric and obstetric settings. Dose-dependent effects of ketamine on cellular proliferation in the neurogenic regions of rat fetal cortex [ventricular zone (VZ) and subventricular zone (SVZ)] were investigated in this in vivo study.

METHODS

Timed-pregnant Sprague-Dawley rats at embryonic day 17 (E17) were given with different doses of ketamine intraperitoneally (0, 1, 2, 10, 20, 40, and 100 mg/kg). Proliferating cells in the rat fetal brains were labeled by injecting 100 mg/kg of 5-bromo-2'-deoxyuridine (BrdU) intraperitoneally. BrdU-labeled cells were detected by immunostaining methods. The numbers of BrdU-positive cells in VZ and SVZ of rat fetal cortex were employed to quantify proliferation in the developing rat cortex.

RESULTS

Ketamine dose-dependently reduced the number of BrdU-positive cells in VZ (P < 0.001) and SVZ (P < 0.001) of the rat fetal cortex. SVZ showed greater susceptibility to ketamine-induced reduction of proliferation in rat fetal cortex, occurring even at clinically relevant doses (2 mg/kg).

CONCLUSION

These data suggest that exposure to ketamine during embryogenesis can dose-dependently inhibit the cellular proliferation in neurogenic regions of the rat fetal cortex.

Repeated, high-dose dextromethorphan treatment decreases neurogenesis and results in depression-like behavior in rats

Abuse of cough mixture is increasingly prevalent worldwide. Clinical studies showed that chronic consumption of cough mixture at high dosages may lead to psychiatric symptoms, especially affective disturbances, with the underlying mechanisms remain elusive. The present study aims at exploring the effect of repeated, high-dose dextromethorphan (DXM, a common active component of cough mixture) treatment on adult hippocampal neurogenesis, which is associated with pathophysiology of mood disturbances. After treatment with a high-dose of DXM (40 mg/kg/day) for 2 weeks, Sprague-Dawley rats showed increased depression-like behavior when compared to the control animals. Neurogenesis in the hippocampus was suppressed by DXM treatment, which was indicated by decreases in number of proliferative cells and doublecortin (an immature neuron marker)-positive new neurons. Furthermore, the dendritic complexity of the immature neurons was suppressed by DXM treatment. These findings suggest that DXM induces depression- and anxiety-like behavior and suppresses neurogenesis in rats. The current experimental paradigm may serve as an animal model for study on affective effect of cough mixture abuse, rehabilitation treatment options for abusers and the related neurological mechanisms.

Systemic physiology and neuroapoptotic profiles in young and adult rats exposed to surgery: A randomized controlled study comprising four different anaesthetic techniques

BACKGROUND

Experimental evidence indicates that general anaesthetics can induce apoptotic neurodegeneration in the developing brain. The majority of these studies have been performed in the absence of surgery and it currently remains unclear how the presence of surgical stimuli would influence neuroapoptosis as well as systemic homeostasis. Here we explored this possibility by performing dorsal skin flap surgery in young and adult rats under four distinct currently used anaesthesia regimens.

METHODS

Young (21-days) and adult (2 months) male Sprague-Dawley rats were randomized to 150 min exposure to one of four anaesthetics regimens: (i) sevoflurane/dexmedetomidine, (ii) sevoflurane/fentanyl; (iii) propofol/dexmedetomidine, and (iv) propofol/fentanyl. Animals underwent a dorsal skin flap procedure while physiologic, metabolic and biochemical parameters were closely monitored. Neuroapoptotic profiles were evaluated in the cortex, thalamus and hippocampus (CA1 and CA3) at the end of the procedure in each experimental group.

RESULTS

Significant perturbations of systemic homeostasis were found under all anaesthetic regimens. Hyperglycemia and decreased heart rate were particularly relevant in experimental groups receiving dexmedetomidine, while propofol administration was associated with increased systemic lactate levels and metabolic acidosis. A substantial difference in anaesthesia/surgery-induced neuroapoptosis was found between young and adult rats in several brain regions. Combination of sevoflurane and dexmedetomidine resulted in the highest number of caspase-3 positive cells, although the extent of cell death remained relatively low in all experimental groups.

CONCLUSION

Combination of anaesthesia and surgery induces significant perturbations of physiological parameters in both young and adult spontaneously breathing rats undergoing surgery. These observations further enlighten the need for detailed physiological monitoring under these experimental conditions. Although some statistically significant differences in activated caspase-3 profiles were detected between experimental groups, the overall extent of neuronal cell death remained very low under all conditions questioning, thereby, the physiological significance of apoptotic neurodegeneration in the context of anaesthesia and surgery.

Pain in children--are we accomplishing the optimal pain treatment?

Morphine, paracetamol and local anesthetics have for a long time been the foremost used analgesics in the pediatric patient by tradition but not always enough effective and associated with side effects. The purpose with this article is to propose alternative approaches in pain management, not always supported up by substantial scientific work but from a combination of science and clinical experience in the field. The scientific literature has been reviewed in parts regarding different aspects of pain assessment and analgesics used for treatment of diverse pain conditions with focus on procedural and acute pain. Clinical experience has been added to form the suggested improvements in accomplishing an improved pain management in pediatric patients. The aim with pain management in children should be a tailored analgesic medication with an individual acceptable pain level and optimal degree of mobilization with as little side effects as possible. Simple techniques of pain control are as effective as and complex techniques in pediatrics but the technique used is not of the highest importance in achieving a good pain management. Increased interest and improved education of the doctors prescribing analgesics is important in accomplishing a better pain management. The optimal treatment with analgesics is depending on the analysis of pain origin and analgesics used should be adjusted thereafter. A multimodal treatment regime is advocated for optimal analgesic effect.

Positron Emission Tomography with [(18)F]FLT Revealed Sevoflurane-Induced Inhibition of Neural Progenitor Cell Expansion in vivo

Neural progenitor cell expansion is critical for normal brain development and an appropriate response to injury. During the brain growth spurt, exposures to general anesthetics, which either block the N-methyl-d-aspartate receptor or enhance the γ-aminobutyric acid receptor type A can disturb neuronal transduction. This effect can be detrimental to brain development. Until now, the effects of anesthetic exposure on neural progenitor cell expansion in vivo had seldom been reported. Here, minimally invasive micro positron emission tomography (microPET) coupled with 3'-deoxy-3' [(18)F] fluoro-l-thymidine ([(18)F]FLT) was utilized to assess the effects of sevoflurane exposure on neural progenitor cell proliferation. FLT, a thymidine analog, is taken up by proliferating cells and phosphorylated in the cytoplasm, leading to its intracellular trapping. Intracellular retention of [(18)F]FLT, thus, represents an observable in vivo marker of cell proliferation. Here, postnatal day 7 rats (n = 11/group) were exposed to 2.5% sevoflurane or room air for 9 h. For up to 2 weeks following the exposure, standard uptake values (SUVs) for [(18)F]-FLT in the hippocampal formation were significantly attenuated in the sevoflurane-exposed rats (p < 0.0001), suggesting decreased uptake and retention of [(18)F]FLT (decreased proliferation) in these regions. Four weeks following exposure, SUVs for [(18)F]FLT were comparable in the sevoflurane-exposed rats and in controls. Co-administration of 7-nitroindazole (30 mg/kg, n = 5), a selective inhibitor of neuronal nitric oxide synthase, significantly attenuated the SUVs for [(18)F]FLT in both the air-exposed (p = 0.00006) and sevoflurane-exposed rats (p = 0.0427) in the first week following the exposure. These findings suggested that microPET in couple with [(18)F]FLT as cell proliferation marker could be used as a non-invasive modality to monitor the sevoflurane-induced inhibition of neural progenitor cell proliferation in vivo.

Does surgery accelerate progression of amyotrophic lateral sclerosis?

BACKGROUND

Surgery is not a recognised potential amyotrophic lateral sclerosis (ALS) risk factor that might modify the onset or course of ALS.

METHODS

We studied our database of ALS patients, which includes questions concerning surgical procedures. We defined surgery as an operative procedure requiring general or regional anaesthesia, but not local anaesthesia. Patients were classified as G1-no surgery; G2-surgery performed ≥3 months before disease onset; G3-surgery <3 months before disease onset; and G4-surgery after disease onset. The ALS-FRS score was evaluated every 3 months from presentation. The maximal ALS-FRS score was ascribed to disease onset, itself defined as symptom onset.

RESULTS

657 patients with ALS were studied. In G3 there was a positive correlation between onset-region and surgery-region (p=0.032). In G4, 35 (57.6%) patients had surgery, probably due to initial misdiagnosis. The rate of functional change (%) in G4 was significantly greater in the 3-month period immediately after surgery as compared with the 3-month period before (1.46%±1.35 vs. 6.30%±8.10, p=0.005) and the following 3 months (3.30%±3.10, p=0.006).

CONCLUSIONS

The site of surgery before ALS onset correlates with the region of onset of ALS. Patients with slower disease progression are at an increased risk of undergoing surgery, probably as part of initial difficulty in diagnosis. We noted accelerated disease progression during the 3-month period after surgery. Definite diagnosis is important to avoid unnecessary surgical trauma and subsequent more rapid deterioration.

Regional gray matter volume increases following 7days of voluntary wheel running exercise: a longitudinal VBM study in rats

The effects of physical exercise on brain morphology in rodents have been well documented in histological studies. However, to further understand when and where morphological changes occur in the whole brain, a noninvasive neuroimaging method allowing an unbiased, comprehensive, and longitudinal investigation of brain morphology should be used. In this study, we investigated the effects of 7days of voluntary wheel running exercise on regional gray matter volume (rGMV) using longitudinal voxel-based morphometry (VBM) in rats. Eighteen pairs of adult male naïve Wistar rats were randomized to the exercise or control condition (one rat for each condition from each pair). Each rat was scanned in a 7.0-T MRI scanner at three time points: before exercise, after 7days of exercise, and after 7days of follow-up. The T2-weighted MRI images were segmented using the rat brain tissue priors that were recently published by our laboratory, and the intra- and inter-subject template creation steps were followed. Longitudinal VBM analysis revealed significant increases in rGMV in the motor, somatosensory, association, and visual cortices in the exercise group. Among these brain regions, rGMV changes in the motor cortex were positively correlated with the total distance that was run during the 7days of exercise. In addition, the effects of 7days of exercise on rGMV persisted after 7days of follow-up. These results support the utility of a longitudinal VBM study in rats and provide new insights into experience-dependent structural brain plasticity in naïve adult animals.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

Propofol impairs neurogenesis and neurologic recovery and increases mortality rate in adult rats after traumatic brain injury

OBJECTIVE

Limited data are available on the influence of sedation for critical care therapy with the widely used anesthetic propofol on recovery from acute traumatic brain injury. To establish the influence of propofol on endogenous neurogenesis and functional recovery after traumatic brain injury, rats were sedated with propofol either during or 2 hours after experimental traumatic brain injury.

DESIGN

Randomized controlled animal study.

SETTING

University research laboratory.

SUBJECTS

One hundred sixteen male Sprague Dawley rats.

INTERVENTIONS

Mechanical brain lesion by controlled cortical impact.

MEASUREMENTS AND MAIN RESULTS

This study investigated the dose-dependent influence of propofol (36 or 72 mg/kg/hr) either during controlled cortical impact induction or in a delayed application protocol 2 hours after experimental traumatic brain injury. Infusion of propofol resulted in 1) aggravation of neurologic dysfunction, 2) increased 28-day mortality rate, and 3) impaired posttraumatic neurogenesis (5-bromo-2-deoxyuridine + NeuN-positive cells). Application of propofol during trauma induction afforded a significant stronger effect in the high-dose group compared with low-dose propofol. In the posttrauma protocol, animals were sedated with sevoflurane during the controlled cortical impact injury, and propofol was given after an awake phase. In these animals, propofol increased mortality rate and impaired neurologic function and neurogenesis compared with animals without delayed propofol anesthesia.

CONCLUSIONS

The results show that propofol may prevent or limit reparative processes in the early-phase postinjury. The results therefore indicate that anesthetics may be potentially harmful not only in very young mammalians but also in adult animals following acute cerebral injuries. The results provide first evidence for an altered sensitivity for anesthesia-related negative effects on neurogenesis, functional outcome, and survival in adult rats with brain lesions.

Perinatal supplementation with omega-3 polyunsaturated fatty acids improves sevoflurane-induced neurodegeneration and memory impairment in neonatal rats

Objectives

To investigate if perinatal Omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplementation can improve sevoflurane-induced neurotoxicity and cognitive impairment in neonatal rats.

Methods

Female Sprague-Dawley rats (n = 3 each group) were treated with or without an n-3 PUFAs (fish oil) enriched diet from the second day of pregnancy to 14 days after parturition. The offspring rats (P7) were treated with six hours sevoflurane administration (one group without sevoflurane/prenatal n-3 PUFAs supplement as control). The 5-bromodeoxyuridine (Brdu) was injected intraperitoneally during and after sevoflurane anesthesia to assess dentate gyrus (DG) progenitor proliferation. Brain tissues were harvested and subjected to Western blot and immunohistochemistry respectively. Morris water maze spatial reference memory, fear conditioning, and Morris water maze memory consolidation were tested at P35, P63 and P70 (n = 9), respectively.

Results

Six hours 3% sevoflurane administration increased the cleaved caspase-3 in the thalamus, parietal cortex but not hippocampus of neonatal rat brain. Sevoflurane anesthesia also decreased the neuronal precursor proliferation of DG in rat hippocampus. However, perinatal n-3 PUFAs supplement could decrease the cleaved caspase-3 in the cerebral cortex of neonatal rats, and mitigate the decrease in neuronal proliferation in their hippocampus. In neurobehavioral studies, compared with control and n-3 PUFAs supplement groups, we did not find significant spatial cognitive deficit and early long-term memory impairment in sevoflurane anesthetized neonatal rats at their adulthood. However, sevoflurane could impair the immediate fear response and working memory and short-term memory. And n-3 PUFAs could improve neurocognitive function in later life after neonatal sevoflurane exposure.

Conclusion

Our study demonstrated that neonatal exposure to prolonged sevoflurane could impair the immediate fear response, working memory and short-term memory of rats at their adulthood, which may through inducing neuronal apoptosis and decreasing neurogenesis. However, these sevoflurane-induced unfavorable neuronal effects can be mitigated by perinatal n-3 PUFAs supplementation.

Antioxidants that protect mitochondria reduce interleukin-6 and oxidative stress, improve mitochondrial function, and reduce biochemical markers of organ dysfunction in a rat model of acute sepsis

Background

Sepsis-induced organ failure is the major cause of death in critical care units, and is characterized by a massive dysregulated inflammatory response and oxidative stress. We investigated the effects of treatment with antioxidants that protect mitochondria (MitoQ, MitoE, or melatonin) in a rat model of lipopolysaccharide (LPS) plus peptidoglycan (PepG)-induced acute sepsis, characterized by inflammation, mitochondrial dysfunction and early organ damage.

Methods

Anaesthetized and ventilated rats received an i.v. bolus of LPS and PepG followed by an i.v. infusion of MitoQ, MitoE, melatonin, or saline for 5 h. Organs and blood were then removed for determination of mitochondrial and organ function, oxidative stress, and key cytokines.

Results

MitoQ, MitoE, or melatonin had broadly similar protective effects with improved mitochondrial respiration (P<0.002), reduced oxidative stress (P<0.02), and decreased interleukin-6 levels (P=0.0001). Compared with control rats, antioxidant-treated rats had lower levels of biochemical markers of organ dysfunction, including plasma alanine amino-transferase activity (P=0.02) and creatinine concentrations (P<0.0001).

Conclusions

Antioxidants that act preferentially in mitochondria reduce mitochondrial damage and organ dysfunction and decrease inflammatory responses in a rat model of acute sepsis.

Anesthesia and the quantitative evaluation of neurovascular coupling

Anesthesia has broad actions that include changing neuronal excitability, vascular reactivity, and other baseline physiologies and eventually modifies the neurovascular coupling relationship. Here, we review the effects of anesthesia on the spatial propagation, temporal dynamics, and quantitative relationship between the neural and vascular responses to cortical stimulation. Previous studies have shown that the onset latency of evoked cerebral blood flow (CBF) changes is relatively consistent across anesthesia conditions compared with variations in the time-to-peak. This finding indicates that the mechanism of vasodilation onset is less dependent on anesthesia interference, while vasodilation dynamics are subject to this interference. The quantitative coupling relationship is largely influenced by the type and dosage of anesthesia, including the actions on neural processing, vasoactive signal transmission, and vascular reactivity. The effects of anesthesia on the spatial gap between the neural and vascular response regions are not fully understood and require further attention to elucidate the mechanism of vascular control of CBF supply to the underlying focal and surrounding neural activity. The in-depth understanding of the anesthesia actions on neurovascular elements allows for better decision-making regarding the anesthetics used in specific models for neurovascular experiments and may also help elucidate the signal source issues in hemodynamic-based neuroimaging techniques.

Mechanistic insights into neurotoxicity induced by anesthetics in the developing brain

Compelling evidence has shown that exposure to anesthetics used in the clinic can cause neurodegeneration in the mammalian developing brain, but the basis of this is not clear. Neurotoxicity induced by exposure to anesthestics in early life involves neuroapoptosis and impairment of neurodevelopmental processes such as neurogenesis, synaptogenesis and immature glial development. These effects may subsequently contribute to behavior abnormalities in later life. In this paper, we reviewed the possible mechanisms of anesthetic-induced neurotoxicity based on new in vitro and in vivo findings. Also, we discussed ways to protect against anesthetic-induced neurotoxicity and their implications for exploring cellular and molecular mechanisms of neuroprotection. These findings help in improving our understanding of developmental neurotoxicology and in avoiding adverse neurological outcomes in anesthesia practice.

Comparison of chemical-induced changes in proliferation and apoptosis in human and mouse neuroprogenitor cells

There is a need to develop rapid and efficient models to screen chemicals for their potential to cause developmental neurotoxicity. Use of in vitro neuronal models, including human cells, is one approach that allows for timely, cost-effective toxicity screening. The present study compares the sensitivity of human (ReN CX) and mouse (mCNS) neuroprogenitor cell lines to chemicals using a multiplex assay for proliferation and apoptosis, endpoints that are critical for neural development. Cells were exposed to 0.001-100 μM concentrations of 11 chemicals (cadmium, chlorpyrifos oxon, dexamethasone, dieldrin, ketamine, lead, maneb, methylmercury, nicotine, trans-retinoic acid, and trimethyltin) reported in the literature to affect proliferation and/or apoptosis, and 5 chemicals (dimethyl pthalate, glyphosate, omeprazole, saccharin, and d-sorbitol) with no reports of effects on either endpoint. High-content screening of markers for proliferation (BrdU incorporation) and apoptosis (activated caspase 3 and p53) was used to assess the effect of chemicals in both cell lines. Of the chemicals tested, methylmercury, cadmium, dieldrin, chlorpyrifos oxon, trans-retinoic acid, and trimethyltin decreased proliferation by at least 50% of control in either the ReN CX or mCNS cells. None of the chemicals tested activated caspase 3 or p53 in the ReN CX cells, while methylmercury, cadmium, dieldrin, chlorpyrifos oxon, trimethyltin, and glyphosate all induced at least a doubling in these apoptotic markers in the mCNS cells. Compared to control, cadmium, trans-retinoic acid, and trimethyltin decreased cell viability (ATP levels) by at least 50% in the ReN CX cells, while cadmium, dieldrin, and methylmercury decreased viability by at least 50% in the mCNS cells. Based on these results, BrdU is an appropriate marker for assessing chemical effects on proliferation, and human cells are more sensitive than mouse cells for this endpoint. By contrast, caspase 3 and p53 were altered by environmental chemicals in mouse, but not in human cells. Therefore, these markers are not appropriate to assess the ability of environmental chemicals to induce apoptosis in the ReN CX cells.

Quantitative assessment of new cell proliferation in the dentate gyrus and learning after isoflurane or propofol anesthesia in young and aged rats

There is a growing body of evidence showing that a statistically significant number of people experience long-term changes in cognition after anesthesia. We hypothesize that this cognitive impairment may result from an anesthetic-induced alteration of postnatal hippocampal cell proliferation. To test this hypothesis, we investigated the effects of isoflurane and propofol on new cell proliferation and cognition of young (4 month-old) and aged (21 month-old). All rats were injected intraperitoneally (IP) with 50 mg/kg of 5-bromo-2-deoxyuridine (BrdU) immediately after anesthesia. A novel appetitive olfactory learning test was used to assess learning and memory two days after anesthesia. One week after anesthesia, rats were euthanized and the brains analyzed for new cell proliferation in the dentate gyrus, and proliferation and migration of newly formed cells in the subventricular zone to the olfactory bulb. We found that exposure to either isoflurane (p=0.017) or propofol (p=0.006) decreased hippocampal cell proliferation in young, but not in aged rats. This anesthetic-induced decrease was specific to new cell proliferation in the hippocampus, as new cell proliferation and migration to the olfactory bulb was unaffected. Isoflurane anesthesia produced learning impairment in aged rats (p=0.044), but not in young rats. Conversely, propofol anesthesia resulted in learning impairment in young (p=0.01), but not in aged rats. These results indicate that isoflurane and propofol anesthesia affect postnatal hippocampal cell proliferation and learning in an age dependent manner.

Protective effects of lithium treatment for spatial memory deficits induced by tau hyperphosphorylation in splenectomized rats

1. Postoperative cognitive dysfunction has become more prevalent in recent years. We used a splenectomized rat model with postoperative spatial learning and memory deficits to investigate the role of tau hyperphosphorylation and glycogen synthase kinase-3β (GSK-3β) within the hippocampus. 2. Cognitive function was assessed in a Y-maze 1 day before and 1, 3 and 7 days after surgery. We measured site-specific phosphorylation of hippocampal tau (Thr-205 and Ser-396), GSK-3β activity and expression of interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) mRNA and protein as markers of inflammation. We also tested the effects of treatment with lithium chloride (LiCl), a GSK-3β inhibitor. 3. Splenectomy was associated with learning and memory impairment 3 days later, as well as a rapid and massive hyperphosphorylation of hippocampal tau at Thr-205 and Ser-396, activated GSK-3β, and increased IL-1β and TNF-α expression. LiCl completely restored tau hyperphosphorylation to control levels. 4. These data from the splenectomized rat model suggest that inflammatory factors affect tau pathology through the GSK-3β signalling pathway and that LiCl is a promising treatment for postoperative cognitive deficits.

Hippocampal adult neurogenesis is enhanced by chronic eszopiclone treatment in rats

The adult hippocampal dentate gyrus (DG) exhibits cell proliferation and neurogenesis throughout life. We examined the effects of daily administration of eszopiclone (Esz), a commonly used hypnotic drug and gamma-aminobutyric acid (GABA) agonist, compared with vehicle, on DG cell proliferation and neurogenesis, and on sleep-wake patterns. Esz was administered during the usual sleep period of rats, to mimic typical use in humans. Esz treatment for 7 days did not affect the rate of cell proliferation, as measured by 5-bromo-2'-deoxyuridine (BrdU) immunostaining. However, twice-daily Esz administration for 2 weeks increased survival of newborn cells by 46%. Most surviving cells exhibited a neuronal phenotype, identified as BrdU-neuronal nuclei (NeuN) double-labeling. NeuN is a marker of neurons. Non-rapid eye movement sleep was increased on day 1, but not on days 7 or 14 of Esz administration. Delta electroencephalogram activity was increased on days 1 and 7 of treatment, but not on day 14. There is evidence that enhancement of DG neurogenesis is a critical component of the effects of antidepressant treatments of major depressive disorder (MDD). Adult-born DG cells are responsive to GABAergic stimulation, which promotes cell maturation. The present study suggests that Esz, presumably acting as a GABA agonist, has pro-neurogenic effects in the adult DG. This result is consistent with evidence that Esz enhances the antidepressant treatment response of patients with MDD with insomnia.

Hormone interactions confer specific proliferative and histomorphogenic responses in the porcine mammary gland

Mammary gland growth and morphogenesis are regulated by interactions between hormones as much as by their individual actions. The effect of these interactions on the mammary gland phenotype in species other than rodents is relatively undefined. We investigated the individual and combined effects of estrogen (E), progestin (P), and prolactin (PRL) on mammary gland development in gilts. Pigs were shown to have a ductal-lobular parenchyma that underwent hormone-stimulated progression of terminal ductal lobular unit (TDLU) morphogenesis similar to that in the human breast. Ovariectomy plus hypoprolactinemia abolished mammary gland growth. Estrogen alone stimulated mammary epithelial cell proliferation, terminal bud formation, and the progression of TDLU1 structures to a TDLU2 morphotype. Maximal epithelial cell proliferation, DNA content, parenchymal area, and morphological development of the porcine mammary gland were realized following treatment with E+PRL or E+P+PRL. In contrast, P alone did not promote epithelial cell proliferation, TDLU type progression, mammary gland growth, or morphogenesis. These data indicate that interactions between E and PRL are the main determinants of growth and morphogenesis in the porcine mammary gland.

Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Postoperative cognitive decline

Memory loss and lack of concentration are symptoms that frequently occur in patients who have undergone a surgical procedure. Although cognitive function can be assessed using neuropsychological tests, reliable diagnosis of postoperative cognitive decline (POCD) appears to be difficult. Therefore, the true incidence of POCD is unknown. Severe POCD, which is apparent even without neuropsychological testing, is reported most frequently after cardiac and hip-replacement surgery. In these cases, POCD probably reflects microembolic brain injury. Apart from the nature of the surgical procedure, advanced age is the most important risk factor for POCD. The anesthetic technique is not a determinant of POCD: the risk of POCD appears to be similar after both general and regional anesthesia.

Molecular and cellular basis of epileptogenesis in symptomatic epilepsy

Epileptogenesis refers to a process in which an initial brain-damaging insult triggers a cascade of molecular and cellular changes that eventually lead to the occurrence of spontaneous seizures. Cellular alterations include neurodegeneration, neurogenesis, axonal sprouting, axonal injury, dendritic remodeling, gliosis, invasion of inflammatory cells, angiogenesis, alterations in extracellular matrix, and acquired channelopathies. Large-scale molecular profiling of epileptogenic tissue has provided information about the molecular pathways that can initiate and maintain cellular alterations. Currently we are learning how these pathways contribute to postinjury epileptogenesis and recovery process and whether they could be used as treatment targets.

Effects of the hypnotic drug zolpidem on cell proliferation and survival in the dentate gyrus of young and old rats

Sleep loss/disruption has been shown to suppress adult hippocampal neurogenesis. Whether the administration of hypnotic drugs, by promoting sleep, especially in older subjects, who typically exhibit poor sleep, has a beneficial effect on neurogenesis parameters is unknown. We examined the effects of zolpidem, a widely prescribed nonbenzodiazepine hypnotic, on cell proliferation and survival in the dentate gyrus of young ( approximately 2 1/2 months) and old ( approximately 13 months) male Sprague-Dawley rats. Zolpidem (5, 10 or 20 mg/kg, i.p.) or vehicle was administered twice daily, at the beginning and middle of the sleep period, for either 2 days (acute study) or 21 days (chronic study). Proliferation and cell survival were measured by staining for Ki67 or 5-bromo-2'-deoxyurdine (BrdU), respectively. Acute administration of zolpidem produced a suppression of cell proliferation, which attained statistical significance only in the aged animals. The magnitude of the suppressive effect was larger in the hilus than in the subgranular zone (SGZ). In contrast, chronic administration of zolpidem produced little or no effect on proliferation in either age group, despite marked differences in basal proliferation levels between the two age groups. Similarly, there was little change in cell survival following chronic zolpidem administration in young versus old animals. A slight reduction of cell survival in the granular cell layer (GCL)/SGZ was observed in young animals and a slight augmentation in aged animals. To the extent that zolpidem improves sleep, these data suggest little or no benefit of hypnotic drug treatment on neurogenesis parameters in young or old rats.