Low-potency glucocorticoid hydrocortisone has similar neurotoxic effects as high-potency glucocorticoid dexamethasone on neurons in the immature chicken cerebellum

Glucocorticoids in a Neonatal Hyperoxic Lung Injury Model: Pulmonary and Neurotoxic effects

BACKGROUND

We aimed to compare the effect of dexamethasone (Dex), hydrocortisone (Hc), and methylprednisolone (Mpz) at equivalent doses on somatic growth, lung healing, and neurotoxicity in a hyperoxic rat model. We hypothesized that Mpz and Hc would be superior to Dex with less neurotoxicity by exerting similar therapeutic efficacy on the injured lung.

METHODS

Neonatal rats were randomized to control, bronchopulmonary dysplasia (BPD), Dex, Hc, and Mpz groups. All drugs were administered daily following day 15 over 7 days. Histopathological and immunohistochemical analyses of the lung and brain were performed on day 22.

RESULTS

All types had much the same impact on lung repair. Oxidative markers in the lung were similar in the steroid groups. While nuclear factor erythroid 2-related factor and heat-shock protein 70 dropped following steroid treatment, no difference was noted in other biochemical markers in the brain between the study groups. Apoptotic activity and neuron loss in the parietal cortex and hippocampus were noted utmost in Dex, but alike in other BPD groups.

CONCLUSIONS

Mpz does not appear to be superior to Dex or Hc in terms of pulmonary outcomes and oxidative damage in the brain, but safer than Dex regarding apoptotic neuron loss.

IMPACT

This is the first study that compared the pulmonary efficacy and neurotoxic effects of Dex, Hc, and Mpz simultaneously in an established BPD model. This study adds to the literature on the importance of possible antioxidant and protective effects of glucocorticoid therapy in an oxidative stress-exposed brain. Mpz ended up with no more additional neuron loss or apoptosis risk by having interchangeable effects with others for the treatment of established BPD. Mpz and Hc seem safe as a rescue therapy in terms of adverse outcomes for established BPD in which lung and brain tissue is already impaired.

Perspective: Chicken Models for Studying the Ontogenetic Origin of Neuropsychiatric Disorders

Nutrients and xenobiotics cross the blood–placenta barrier, potentially depositing in the fetal brain. The prenatal exposure affects the neuroendocrine and microbial development. The mechanism underlying maternal risk factors reprograming the microbiota–gut–brain axis with long-term effects on psychosocial behaviors in offspring is not clear. In humans, it is not possible to assess the nutrient or xenobiotic deposition in the fetal brain and gastrointestinal system for ethical reasons. Moreover, the maternal–fetal microbe transfer during gestation, natural labor, and breast-feeding constitutes the initial gut microbiome in the progeny, which is inevitable in the most widely utilized rodent models. The social predisposition in precocial birds, including chickens, provides the possibility to test behavioral responses shortly after being hatched. Hence, chickens are advantageous in investigating the ontogenetic origin of behaviors. Chicken embryos are suitable for deposition assessment and mechanistic study due to the accessibility, self-contained development, uniform genetic background, robust microbiota, and easy in vivo experimental manipulation compared to humans and rodents. Therefore, chicken embryos can be used as an alternative to the rodent models in assessing the fetal exposure effect on neurogenesis and investigating the mechanism underlying the ontogenetic origin of neuropsychiatric disorders.

Peripherally administered persistent organic pollutants distribute to the brain of developing chicken embryo in concentrations relevant for human exposure

Persistent organic pollutants (POPs) can reach the fetal brain and contribute to developmental neurotoxicity. To explore the distribution of POPs to the fetal brain, we exposed chicken embryos to a POP mixture, containing 29 different compounds with concentrations based on blood levels measured in the Scandinavian human population. The mixture was injected into the allantois at embryonic day 13 (E13), aiming at a theoretical concentration of 10 times human blood levels. POPs concentrations in the brain were measured at 0.5, 1, 2, 4, 6, 24, 48, and 72 h after administration. Twenty-seven of the individual compounds were detected during at least one of the time-points analyzed. Generally, the concentrations of most of the measured compounds were within the order of magnitude of those reported in human brain samples. Differences in the speed of distribution to the brain were observed between the per- and polyfluoroalkyl substances (PFASs), which have protein binding potential, and the lipophilic polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and brominated flame retardants (BFRs). Based on pharmacokinetic modeling, PFASs were best described by a one compartment model. PFASs displayed relatively slow elimination (Kel) and persisted at high levels in the brain. Lipophilic OCPs and PCBs could be fitted to a 2-compartment model. These showed high levels in the brain relative to the dose administrated as calculated by area under the curve (AUC)/Dose. Altogether, our study showed that chicken is a suitable model to explore the distribution of POPs into the developing brain at concentrations which are relevant for humans.

Cerebellum and Prematurity: A Complex Interplay Between Disruptive and Dysmaturational Events

The cerebellum plays a critical regulatory role in motor coordination, cognition, behavior, language, memory, and learning, hence overseeing a multiplicity of functions. Cerebellar development begins during early embryonic development, lasting until the first postnatal years. Particularly, the greatest increase of its volume occurs during the third trimester of pregnancy, which represents a critical period for cerebellar maturation. Preterm birth and all the related prenatal and perinatal contingencies may determine both dysmaturative and lesional events, potentially involving the developing cerebellum, and contributing to the constellation of the neuropsychiatric outcomes with several implications in setting-up clinical follow-up and early intervention.

A human relevant mixture of persistent organic pollutants (POPs) and perfluorooctane sulfonic acid (PFOS) differentially affect glutamate induced excitotoxic responses in chicken cerebellum granule neurons (CGNs) in vitro

Primary cultures of cerebellar granule neurons (CGNs) derived from chicken embryos were used to explore the effects on developmental neurotoxicity by a complex defined mixture of persistent organic pollutants (POPs). Its chemical composition and concentrations were based on blood levels in the Norwegian/Scandinavian population. Perfluorooctane sulfonic acid (PFOS) alone, its most abundant compound was also evaluated. Different stages of CGNs maturation, between day in vitro (DIV) 1, 3, and 5 were exposed to the POP mixture, or PFOS alone. Their combination with glutamate, an excitatory endogenous neurotransmitter important in neurodevelopment, also known to cause excitotoxicity was evaluated. Outcomes with the mixture at 500x blood levels were compared to PFOS at its corresponding concentration of 20 μM. The POP mixture reduced tetrazolium salt (MTT) conversion at earlier stages of maturation, compared to PFOS alone. Glutamate-induced excitotoxicity was enhanced above the level of that induced by glutamate alone, especially in mature CGNs at DIV5. Glutathione (GSH) concentrations seemed to set the level of sensitivity for the toxic insults from exposures to the pollutants. The role of N-methyl-D-aspartate receptor (NMDA-R) mediated calcium influx in pollutant exposures was investigated using the non-competitive and competitive receptor antagonists MK-801 and CGP 39551. Observations indicate a calcium-independent, but still NMDA-R dependent mechanism in the absence of glutamate, and a calcium- and NMDA-R dependent one in the presence of glutamate. The outcomes for the POP mixture cannot be explained by PFOS alone, indicating that other chemicals in the mixture contribute its overall effect.

The Developing Cerebellum as a Target for Toxic Substances: Protective Role of Antioxidants

Cerebellar development begins during the late embryological period and continues to undergo organizational changes long after birth. The cerebellum is particularly susceptible to developmental abnormalities on exposure to oxidants and free radicals, thus leading to oxidative stress. Oxidative stress occurs when there is an imbalance between reactive oxygen species generation and antioxidant defences which may disrupt signalling pathways, leading to cerebellar anomalies and dysfunction. In this regard, this review assesses current research underlining the importance of the cerebellum, provides an update on substances affecting cerebellar development and highlights some promising antioxidants that may play a role in attenuating toxicity in the developing cerebellum. To accomplish this, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) system was employed and key scientific databases such as Science Direct, PubMed, Scopus, Web of Science and Google Scholar were searched to explore and collect information on the cerebellum and the role of antioxidants during its development. Originally, 109 articles were obtained but 22 articles which met the inclusion criteria were selected for the review. These findings provide an updated compilation of antioxidants capable of attenuating oxidative damage in the developing cerebellum, thus allowing future interdisciplinary studies in the form of clinical applications for screening and possible development of novel therapeutic agents from the identified products.

Impact of prematurity on neurodevelopment

The consequences of prematurity on brain functional development are numerous and diverse, and impact all brain functions at different levels. Prematurity occurs between 22 and 36 weeks of gestation. This period is marked by extreme dynamics in the physiologic maturation, structural, and functional processes. These different processes appear sequentially or simultaneously. They are dependent on genetic and/or environmental factors. Disturbance of these processes or of the fine-tuning between them, when caring for premature children, is likely to induce disturbances in the structural and functional development of the immature neural networks. These will appear as impairments in learning skills progress and are likely to have a lasting impact on the development of children born prematurely. The level of severity depends on the initial alteration, whether structural or functional. In this chapter, after having briefly reviewed the neurodevelopmental, structural, and functional processes, we describe, in a nonexhaustive manner, the impact of prematurity on the different brain, motor, sensory, and cognitive functions.

Human Embryonic Stem Cell-Derived Neural Lineages as In Vitro Models for Screening the Neuroprotective Properties of Lignosus rhinocerus (Cooke) Ryvarden

In the biomedical field, there is growing interest in using human stem cell-derived neurons as in vitro models for pharmacological and toxicological screening of bioactive compounds extracted from natural products. Lignosus rhinocerus (Tiger Milk Mushroom) is used by indigenous communities in Malaysia as a traditional medicine to treat various diseases. The sclerotium of L. rhinocerus has been reported to have medicinal properties, including various bioactivities such as neuritogenic, anti-inflammatory, and anticancer effects. This study aims to investigate the neuroprotective activities of L. rhinocerus sclerotial extracts. Human embryonic stem cell (hESC)-derived neural lineages exposed to the synthetic glucocorticoid, dexamethasone (DEX), were used as the in vitro models. Excess glucocorticoids have been shown to adversely affect fetal brain development and impair differentiation of neural progenitor cells. Screening of different L. rhinocerus sclerotial extracts and DEX on the hESC-derived neural lineages was conducted using cell viability and neurite outgrowth assays. The neuroprotective effects of L. rhinocerus sclerotial extracts against DEX were further evaluated using apoptosis assays and Western blot analysis. Hot aqueous and methanol extracts of L. rhinocerus sclerotium promoted neurite outgrowth of hESC-derived neural stem cells (NSCs) with negligible cytotoxicity. Treatment with DEX decreased viability of NSCs by inducing apoptosis. Coincubation of L. rhinocerus methanol extract with DEX attenuated the DEX-induced apoptosis and reduction in phospho-Akt (pAkt) level in NSCs. These results suggest the involvement of Akt signaling in the neuroprotection of L. rhinocerus methanol extract against DEX-induced apoptosis in NSCs. Methanol extract of L. rhinocerus sclerotium exhibited potential neuroprotective activities against DEX-induced toxicity in hESC-derived NSCs. This study thus validates the use of human stem cell-derived neural lineages as potential in vitro models for screening of natural products with neuroprotective properties.

Descriptive epidemiology of cerebellar hypoplasia in the National Birth Defects Prevention Study

BACKGROUND

Cerebellar hypoplasia is a rare disorder of cerebellar formation in which the cerebellum is not completely developed, smaller than it should be, or completely absent. The prevalence of cerebellar hypoplasia at birth is unknown, and little is known about epidemiological risk factors. Using data from the National Birth Defects Prevention Study (NBDPS), a population-based, case-control study, we analyzed clinical features and potential risk factors for nonsyndromic cerebellar hypoplasia.

METHODS

The NBDPS included pregnancies with estimated delivery dates from 1997-2011. We described clinical features of cerebellar hypoplasia cases from the study area. We explored risk factors for cerebellar hypoplasia (case characteristics, demographics, pregnancy characteristics, maternal health conditions, maternal medication use, and maternal behavioral exposures) by comparing cases to non-malformed live born control infants. We calculated crude odds ratios (ORs) and 95% confidence intervals using logistic regression models.

RESULTS

We identified 87 eligible cerebellar hypoplasia cases and 55 mothers who participated in the NBDPS. There were no differences in clinical features between interviewed and non-interviewed cases. Cerebellar hypoplasia cases were more likely than controls to be from a multiple pregnancy, be born preterm, and have low birth weight. Cerebellar hypoplasia cases were more likely to be born in or after 2005, as opposed to earlier in NBDPS. We found elevated ORs that were not statistically significant for maternal use of vasoactive medications, non-Hispanic black mothers, and mothers with a history of hypertension.

CONCLUSIONS

Although unadjusted, our findings from a large, population-based study can contribute to new hypotheses regarding the etiology of cerebellar hypoplasia.

Corticosteroids for the prevention of bronchopulmonary dysplasia in preterm infants: a network meta-analysis

OBJECTIVE

To determine the comparative efficacy and safety of corticosteroids in the prevention of bronchopulmonary dysplasia (BPD) in preterm infants.

STUDY DESIGN

We systematically searched PubMed, EMBASE and the Cochrane Library. Two reviewers independently selected randomised controlled trials (RCTs) of postnatal corticosteroids in preterm infants. A Bayesian network meta-analysis and subgroup analyses were performed.

RESULTS

We included 47 RCTs with 6747 participants. The use of dexamethasone at either high dose or low dose decreased the risk of BPD (OR 0.29, 95% credible interval (CrI) 0.14 to 0.52; OR 0.58, 95% CrI 0.39 to 0.76, respectively). High-dose dexamethasone was more effective than hydrocortisone, beclomethasone and low-dose dexamethasone. Early and long-term dexamethasone at either high dose or low dose decreased the risk of BPD (OR 0.11, 95% CrI 0.02 to 0.4; OR 0.37, 95% CrI 0.16 to 0.67, respectively). There were no statistically significant differences in the risk of cerebral palsy (CP) between different corticosteroids. However, high-dose and long-term dexamethasone ranked lower than placebo and other regimens in terms of CP. Subgroup analyses indicated budesonide was associated with a decreased risk of BPD in extremely preterm and extremely low birthweight infants (OR 0.60, 95% CrI 0.36 to 0.93).

CONCLUSIONS

Dexamethasone can reduce the risk of BPD in preterm infants. Of the different dexamethasone regimens, aggressive initiation seems beneficial, while a combination of high-dose and long-term use should be avoided because of the possible adverse neurodevelopmental outcome. Dexamethasone and inhaled corticosteroids need to be further evaluated in large-scale RCTs with long-term follow-ups.

Cerebellar injury in preterm infants

Although preterm birth is best known to result in adverse neurodevelopmental outcomes through injury of the supratentorial structures, including intraventricular hemorrhage and periventricular leukomalacia, the cerebellum has become increasingly recognized as an important target for injury and adverse motor and cognitive outcomes. Undergoing the most dramatic growth during the preterm period, the cerebellum is vulnerable to large and small hemorrhages, as well as hypoplasia resulting from a number of potentially modifiable risk factors. These factors include contact with intraventricular blood, crossed cerebrocerebellar diaschisis, postnatal glucocorticoid exposure, pain and opioid exposure, nutrition and somatic growth, cardiorespiratory factors, and socioeconomic status. Strategies targeting these factors may result in prevention of the motor and cognitive deficits seen after cerebellar hemorrhage or hypoplasia.

Glucocorticoid Effects on Cerebellar Development in a Chicken Embryo Model: Exploring Changes in PAX6 and Metalloproteinase-9 After Exposure to Dexamethasone

The developing cerebellum is vulnerable to effects of glucocorticoids and cerebellar dysfunction is associated with neurodevelopmental disorders (e.g. autism). Transcription factor PAX6 and matrix metalloproteinase-9 (MMP-9) are critical for normal cerebellar development and are highly expressed in migrating neurones. Alterations in MMP-9 and PAX6 are associated with altered cerebellar development. In the present study, we characterised the growth rate and development of the cortical layers, and further investigated how the levels of PAX6 and MMP-9, as well as glucocorticoid receptor (GR) and proliferating cell nuclear antigen (PCNA), change in the cerebellum during the foetal period [embryonic day (E)12-21] in chicken, which corresponds to the human perinatal period. Dexamethasone (DEX) was administered in ovo at E13 and E16, aiming to investigate how prenatal exposure to glucocorticoids interferes with normal development. DEX reduced foetal and cerebellar weight at E17 in a dose-dependent manner linked to a reduced level of PCNA and, over time, down-regulation of GR. We report that promoter activity of PAX6 and MMP-9 increased as a result of GR-stimulation in vitro. Prenatal DEX increased the protein level of PAX6 in a transient manner. PAX6 is reduced in mature granule neurones, and this occurred earlier in embryos exposed to DEX than in non-exposed controls. DEX exposure also led to a slow-onset down-regulation of MMP-9. Taken together, these findings indicate that excess prenatal glucocorticoid stimulation disturbs normal development of the cerebellum through mechanisms associated with reduced proliferation and accelerated maturation where PAX6 and MMP-9 play important roles.

Pharmacological approaches to intervention in hypomyelinating and demyelinating white matter pathology

White matter disease afflicts both developing and mature central nervous systems. Both cell intrinsic and extrinsic dysregulation result in profound changes in cell survival, axonal metabolism and functional performance. Experimental models of developmental white matter (WM) injury and demyelination have not only delineated mechanisms of signaling and inflammation, but have also paved the way for the discovery of pharmacological approaches to intervention. These reagents have been shown to enhance protection of the mature oligodendrocyte cell, accelerate progenitor cell recruitment and/or differentiation, or attenuate pathological stimuli arising from the inflammatory response to injury. Here we highlight reports of studies in the CNS in which compounds, namely peptides, hormones, and small molecule agonists/antagonists, have been used in experimental animal models of demyelination and neonatal brain injury that affect aspects of excitotoxicity, oligodendrocyte development and survival, and progenitor cell function, and which have been demonstrated to attenuate damage and improve WM protection in experimental models of injury. The molecular targets of these agents include growth factor and neurotransmitter receptors, morphogens and their signaling components, nuclear receptors, as well as the processes of iron transport and actin binding. By surveying the current evidence in non-immune targets of both the immature and mature WM, we aim to better understand pharmacological approaches modulating endogenous oligodendroglia that show potential for success in the contexts of developmental and adult WM pathology. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.

Calcium-induced apoptosis of developing cerebellar granule neurons depends causally on NGFI-B

Immediate early gene nerve growth factor-induced clone B (NGFI-B), a nuclear receptor important for differentiation and apoptosis, is expressed in mice and rat cerebellum from an early stage of postnatal development. Following apoptotic stimuli NGFI-B translocates to mitochondria to initiate cell death processes. Controlled cell death is critical for correct cerebellar development. Immunohistochemical analysis of NGFI-B in sections of mice cerebella showed NGFI-B to be expressed in granule neurons in vivo at a time (P8-11) when apoptosis is known to occur. The importance of NGFI-B for apoptosis of cultured rat cerebellar granule neurons was investigated by inducing apoptosis with calcium ionophore A23187 (CaI, 0.1μM). Imaging studies of gfp-tagged NGFI-B confirmed that mitochondrial translocation of NGFI-B occurred following treatment with CaI and was reduced by addition of 9-cis-retinoic acid (1μM), a retinoid X receptor (RXR) agonist that prevents dimerization of RXR and NGFI-B that is known to occur before translocation. Consequently, 9-cis-retinoic acid partly reduced cell death. To address the causality of NGFI-B in apoptosis further, knock-down by siRNA was performed and it removed 85% of the NGFI-B protein. This resulted in a complete inhibition of apoptosis after CaI exposure. Together these findings suggest that NGFI-B plays a role in controlling correct cerebellar development.

Dexamethasone but not the equivalent doses of hydrocortisone induces neurotoxicity in neonatal rat brain

BACKGROUND

The use of dexamethasone (Dex) in premature infants to treat or prevent chronic lung disease adversely affects neurodevelopment. Recent clinical studies suggest that hydrocortisone (HC) is a safer alternative to Dex. We compared the effects of Dex and HC on neurotoxicity in newborn rats.

METHODS

Rat pups of a neurodevelopmental stage equivalent to premature human neonates were administered Dex or HC either as a single dose on postnatal day (PD) 6, repeated doses on PD 4 to 6 or tapering doses at PD 3 to 6 by i.p. injection. Brain weight, caspase-3 activity, and apoptotic cells were measured at PD 7; learning capability, memory, and motor function were measured at juvenile age.

RESULTS

Dex decreased both body and brain weight gain, while HC did not. Tapering and repeated doses of Dex increased caspase-3 activity, cleaved caspase-3 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells but HC, except at high doses, did not. Dex impaired learning and memory capability at juvenile age, while the rats exposed to HC showed normal cognitive behavior.

CONCLUSION

HC is probably safer to use than Dex in the immediate postnatal period in neonatal rats. Cautious extrapolation of these findings to human premature infants is required.

Adrenal steroids in the brain: role of the intrinsic expression of corticosteroid-binding globulin (CBG) in the stress response

The complex interaction between hypothalamus, pituitary and adrenal glands is a key component of the neuroendocrine stress response. The major stress hormones--glucocorticoids--have both central and peripheral effects. Among the factors regulating their availability to target tissues are levels of corticosteroid-binding globulin, as the major transport protein for glucocorticoids in systemic circulation. Our recent findings demonstrated expression of corticosteroid-binding globulin in various brain regions and in different cell populations (neurons and glial cells). We showed at the cellular level the presence of corticosteroid-binding globulin in the human hypothalamus, where it was co-localized with the classical neurohypophyseal neurohormones--vasopressin and oxytocin. For the first time we demonstrated in mouse that the same gene encodes brain and liver corticosteroid-binding globulin. The full-length sequencing of hypothalamic corticosteroid-binding globulin revealed a full homology with liver corticosteroid-binding globulin cDNA. Thus, we confirmed that corticosteroid-binding globulin mRNA is produced locally within various cerebral regions and thus not transported from blood. However, the amounts of mRNA encoding corticosteroid-binding globulin are in liver about 200 times higher than in brain. The wide distribution of corticosteroid-binding globulin, distinct from the localization of glucocorticoid receptors, observed in our comparative study in rodents, led us to propose two possibilities: (1) corticosteroid-binding globulin is made in certain neurons to deliver glucocorticoids into the cell and within the cell in the absence of cytoplasmic glucocorticoid receptors or (2) is internalized into neurons specifically to deliver glucocorticoids to classical glucocorticoid receptors. Brain corticosteroid-binding globulin may be involved in the response to changing systemic glucocorticoid levels either additionally to known nuclear and membrane corticosteroid receptors or in glucocorticoid responsive brain regions devoid of these receptors. Clearly the multiple locations of corticosteroid-binding globulin within the central nervous system of humans and rodents imply multiple functional properties in normal and/or pathological conditions, which are yet to be determined. Most likely, the importance of brain corticosteroid-binding globulin exceeds the function of a mere steroid transporter.

Potential mechanisms of cerebellar hypoplasia in prematurity

INTRODUCTION

The cerebellum undergoes dramatic growth and maturation over the neonatal period after preterm birth and is thus particularly sensitive to impaired development due to various clinical factors.

METHODS

Impairments in growth can occur independent of cerebellar parenchymal damage, such as from local hemorrhage, resulting from reduced expression of sonic hedgehog signaling to trigger the appropriate expansion of the granule precursor cells.

RESULTS

The primary risk factors for impaired cerebellar development include postnatal glucocorticoid exposure, which has direct effects on the sonic hedgehog pathway, and supratentorial brain injury, including intraventricular hemorrhage and white matter injury, which may result in crossed cerebellar diaschisis and local toxic effects of blood products on the external granular layer. Other cardiorespiratory and nutritional factors may also exist. Impaired cerebellar development is associated with adverse outcomes in motor and cognitive development.

CONCLUSION

New approaches to care to counteract these risk factors may help improve long-term outcome after preterm birth.

Cerebellar granule cells are generated postnatally in humans

How many cerebellar granule cells are generated pre- or postnatally in human is unknown. Using a rigorous design-based stereologic approach we investigated postmortem cerebella from 14 children who died between the first postnatal day (P1) and 11 months of age (M11). We found a statistically significant (p < 0.05) age-related increase in the total number of granule cells from 5.9 × 10(9) at M1 to 37.6 × 10(9) at M10/11 per cerebellar half but not in the total number of Purkinje cells (12.1 × 10(6) at M1 vs. 13.9 × 10(6) at M10/11 per cerebellar half). Accordingly, approximately 85 % of the cerebellar granule cells are generated postnatally in human, and the number of granule cells per Purkinje cell in the human cerebellum increases from 485 at M1 to 2,700 at M10/11, approximately. These data indicate that the human cerebellum has a much higher functional plasticity during the first year of life than previously thought, and may respond very sensitively to internal and external influences during this time. This has important implications for several neuropsychiatric conditions in which cerebellar involvement has been demonstrated.

Epidural steroid injections are associated with less improvement in patients with lumbar spinal stenosis: a subgroup analysis of the Spine Patient Outcomes Research Trial

STUDY DESIGN

Subgroup analysis of prospective, randomized database from the Spine Patient Outcomes Research Trial (SPORT).

OBJECTIVE

The hypothesis of this study was that patients who received ESI during initial treatment as part of SPORT (The Spine Patient Outcomes Research Trial) would have improved clinical outcome and a lower rate of crossover to surgery than patients who did not receive ESI.

SUMMARY OF BACKGROUND DATA

The use of epidural steroid injection (ESI) in patients with lumbar spinal stenosis is common, although there is little evidence in the literature to demonstrate its long-term benefit in the treatment of lumbar stenosis.

METHODS

Patients with lumbar spinal stenosis who received ESI within the first 3 months of enrollment in SPORT (ESI) were compared with patients who did not receive epidural injections during the first 3 months of the study (no-ESI).

RESULTS

There were 69 ESI patients and 207 no-ESI patients. There were no significant differences in demographic factors, baseline clinical outcome scores, or operative details between the groups, although there was a significant increase in baseline preference for nonsurgical treatment among ESI patients (ESI 62% vs. no-ESI 33%, P < 0.001). There was an average 26-minute increase in operative time and an increased length of stay by 0.9 days among the ESI patients who ultimately underwent surgical treatment. Averaged over 4 years, there was significantly less improvement in 36-Item Short Form Health Survey (SF-36) Physical Function among surgically treated ESI patients (ESI 14.8 vs. no-ESI 22.5, P = 0.025). In addition, there was significantly less improvement among the nonsurgically treated patients in SF-36 Body Pain (ESI 7.3 vs. no-ESI 16.7, P = 0.007) and SF-36 Physical Function (ESI 5.5 vs. no-ESI 15.2, P = 0.009). Of the patients assigned to the surgical treatment group, there was a significantly increased crossover to nonsurgical treatment among patients who received an ESI (ESI 33% vs. no-ESI 11%, P = 0.012). Of the patients assigned to the nonoperative treatment group, there was a significantly increased crossover to surgical treatment in the ESI patients (ESI 58% vs. no-ESI 32%, P = 0.003).

CONCLUSION

Despite equivalent baseline status, ESIs were associated with significantly less improvement at 4 years among all patients with spinal stenosis in SPORT. Furthermore, ESIs were associated with longer duration of surgery and longer hospital stay. There was no improvement in outcome with ESI whether patients were treated surgically or nonsurgically.

Biocompatibility of chitosan carriers with application in drug delivery

Chitosan is one of the most used polysaccharides in the design of drug delivery strategies for administration of either biomacromolecules or low molecular weight drugs. For these purposes, it is frequently used as matrix forming material in both nano and micron-sized particles. In addition to its interesting physicochemical and biopharmaceutical properties, which include high mucoadhesion and a great capacity to produce drug delivery systems, ensuring the biocompatibility of the drug delivery vehicles is a highly relevant issue. Nevertheless, this subject is not addressed as frequently as desired and even though the application of chitosan carriers has been widely explored, the demonstration of systems biocompatibility is still in its infancy. In this review, addressing the biocompatibility of chitosan carriers with application in drug delivery is discussed and the methods used in vitro and in vivo, exploring the effect of different variables, are described. We further provide a discussion on the pros and cons of used methodologies, as well as on the difficulties arising from the absence of standardization of procedures.

Preterm cerebellar growth impairment after postnatal exposure to glucocorticoids

As survival rates of preterm newborns improve as a result of better medical management, these children increasingly show impaired cognition. These adverse cognitive outcomes are associated with decreases in the volume of the cerebellum. Because animals exhibit reduced preterm cerebellar growth after perinatal exposure to glucocorticoids, we sought to determine whether glucocorticoid exposure and other modifiable factors increased the risk for these adverse outcomes in human neonates. We studied 172 preterm neonatal infants from two medical centers, the University of British Columbia and the University of California, San Francisco, by performing serial magnetic resonance imaging examinations near birth and again near term-equivalent age. After we adjusted for associated clinical factors, antenatal betamethasone was not associated with changes in cerebellar volume. Postnatal exposure to clinically routine doses of hydrocortisone or dexamethasone was associated with impaired cerebellar, but not cerebral, growth. Alterations in treatment after preterm birth, particularly glucocorticoid exposure, may help to decrease risk for adverse neurological outcome after preterm birth.

Perinatal cerebellar injury in human and animal models

Cerebellar injury is increasingly recognized through advanced neonatal brain imaging as a complication of premature birth. Survivors of preterm birth demonstrate a constellation of long-term neurodevelopmental deficits, many of which are potentially referable to cerebellar injury, including impaired motor functions such as fine motor incoordination, impaired motor sequencing and also cognitive, behavioral dysfunction among older patients. This paper reviews the morphogenesis and histogenesis of the human and rodent developing cerebellum, and its more frequent injuries in preterm. Most cerebellar lesions are cerebellar hemorrhage and infarction usually leading to cerebellar abnormalities and/or atrophy, but the exact pathogenesis of lesions of the cerebellum is unknown. The different mechanisms involved have been investigated with animal models and are primarily hypoxia, ischemia, infection, and inflammation Exposure to drugs and undernutrition can also induce cerebellar abnormalities. Different models are detailed to analyze these various disturbances of cerebellar development around birth.

Intrinsic expression of transcortin in neural cells of the mouse brain: a histochemical and molecular study

Corticosteroid binding globulin (CBG, transcortin) has been shown to be expressed in the brain of rat and human species. In this study we examined the CBG brain expression and cDNA structure in mice, comparing wild-type (Cbg+/+) and Cbg knockout mice (Cbg-/-, obtained by genetic disruption of the SerpinA6 alias Cbg gene). We used double immunofluorescence labelling with specific neuronal and glial markers to analyze the cellular localization of CBG in various regions of the mouse brain. In wild-type (Cbg+/+) mice we found CBG immunoreactivity in neuronal perikarya of the magnocellular hypothalamic nuclei, amygdala, hippocampus, cerebral cortex, cerebellum and pituitary. A portion of glial cells (astrocytes, oligodendrocytes) contained CBG immunoreactivity, including some of the ependymal cells and choroid plexus cells. No CBG immunoreactivity was detected in Cbg-/- brain tissues. We showed by RT-PCR that the full-length Cbg mRNA is present in those regions, indicating an intrinsic expression of the steroid-binding globulin. Furthermore, we found by sequencing analysis that Cbg cDNA obtained from the mouse hypothalamus was homologous to Cbg cDNA obtained from the liver. Finally, we have evaluated the relative levels of CBG expression by quantitative PCR in various brain regions and in the liver. We found that brain levels of Cbg mRNA are low compared to the liver but significantly higher than in CBG-deficient mice. Although derived from the same gene than liver CBG, brain CBG protein may play a specific or complementary role that requires the production and analysis of brain-specific Cbg knockout models.

Fisetin prevents fluoride- and dexamethasone-induced oxidative damage in osteoblast and hippocampal cells

Fluoride intoxication and dexamethasone treatment produce deleterious effects in bone and brain. The aim of this study was to evaluate the effect of fluoride (F) and dexamethasone (Dex) co-exposure on oxidative stress and apoptosis in osteoblast-like MC3T3-E1 and hippocampal HT22 cell lines. Co-exposure to F and Dex resulted in a concentration-dependent decrease in cell viability, induction of apoptosis and increased generation of reactive oxygen species (ROS) and nitric oxide (NO) following 72 h of incubation. Fluoride-induced apoptosis in MC3T3-E1 and HT22 cells was attenuated by catalase and L-NNMA, indicating a role for H2O2 and NO as mediators of cytotoxicity. Dexamethasone-induced apoptosis was associated with H2O2 generation in both cell lines and it was attenuated during co-incubation with catalase. These data indicate that co-exposure to F and Dex amplifies their respective cytotoxicity in H2O2- and NO-dependent manner. As flavonoid fisetin prevented F- and Dex-induced cytotoxicity the potential role of this product in pharmacology and diet may be considered.

Glucocorticoid receptor blockade in the posterior interpositus nucleus reverses maternal separation-induced deficits in adult eyeblink conditioning

Previously, we showed that neonatal maternal separation impaired eyeblink conditioning in adult rats. This impairment is correlated with increased glucocorticoid receptor (GR) expression in the cerebellar posterior interpositus nucleus, a critical site of learning-related plasticity. To assess whether increased GR expression is responsible for the separation-induced learning impairment, we infused a GR antagonist (mifepristone) or vehicle into the posterior interpositus during eyeblink conditioning in adult male Long-Evans rats that had undergone control rearing or neonatal maternal separation (1h/day, postnatal days 2-14). Rats received standard rearing (control) or neonatal maternal separation (separated; 1h/day on postnatal days 2-14). In adulthood, rats underwent surgery for implantation of recording electrodes in the orbicularis oculi of the left eyelid, a bipolar stimulating electrode dorsocaudal to the left eye, and an infusion guide cannula positioned over the posterior interpositus. Then, rats underwent 10 daily sessions of eyeblink conditioning. Rats in each group received either 0.2microl of mifepristone (2ng in 2% EtOH) or vehicle infusion prior to each eyeblink conditioning session. Mifepristone infusions improved conditioning in separated rats, but impaired control rats' performance. Thus, separation-induced increases in GRs may mediate the learning deficit seen in adult neonatally separated rats.

Effects of glucocorticoid on brain acetylcholinesterase of developing chick embryos

AIM

Fetal exposure to excessive or deficient glucocorticoids may alter the programming in differentiation and maturation of various tissues including the brain and nervous system, leading to dysfunctions later in life. For further exploration of this possibility, we established an animal model using developing chick embryos.

METHODS

(i) Reverse-transcription polymerase chain reaction was used to determine the expression of glucocorticoid receptor mRNA in the brain of chick embryos. (ii) Embryos on day 15 were administered betamethasone or mifepristone and their cerebrum, cerebellum and optic lobe were investigated to determine the activity of acetylcholinesterase.

RESULTS

(i) Glucocorticoid receptor mRNA was shown to be present in the cerebrum, cerebellum and optic lobe. (ii) After the administration of betamethasone, acetylcholinesterase activities in the cerebrum, cerebellum and optic lobe on day 19 were 1.5- to 2-fold higher than those of untreated control. Weights of body and brain parts were 0.65-0.75-fold relative to control values. However, these differences were less noticeable on day 22. (iii) Administration of mifepristone before treatment with betamethasone prevented high-dose betamethasone-induced changes in acetylcholinesterase activity and bodyweights on day 19. Administration of mifepristone alone did not induce differences from the control.

CONCLUSIONS

The cerebrum, cerebellum and optic lobe of chick embryos could be influenced by glucocorticoids because of the presence of glucocorticoid receptor mRNA. Although the effects observed after treatment with excess glucocorticoids (even no effects after mifepristone treatment) were transitory, they may alter the developmental program in ways that could result in lasting change and influence behavioral activities after hatching.