Developmental neurotoxicity of alcohol and anesthetic drugs is augmented by co-exposure to caffeine

Extensive characterization of a Williams syndrome murine model shows Gtf2ird1-mediated rescue of select sensorimotor tasks, but no effect on enhanced social behavior

Williams syndrome is a rare neurodevelopmental disorder exhibiting cognitive and behavioral abnormalities, including increased social motivation, risk of anxiety and specific phobias along with perturbed motor function. Williams syndrome is caused by a microdeletion of 26-28 genes on chromosome 7, including GTF2IRD1, which encodes a transcription factor suggested to play a role in the behavioral profile of Williams syndrome. Duplications of the full region also lead to frequent autism diagnosis, social phobias and language delay. Thus, genes in the region appear to regulate social motivation in a dose-sensitive manner. A "complete deletion" mouse, heterozygously eliminating the syntenic Williams syndrome region, has been deeply characterized for cardiac phenotypes, but direct measures of social motivation have not been assessed. Furthermore, the role of Gtf2ird1 in these behaviors has not been addressed in a relevant genetic context. Here, we have generated a mouse overexpressing Gtf2ird1, which can be used both to model duplication of this gene alone and to rescue Gtf2ird1 expression in the complete deletion mice. Using a comprehensive behavioral pipeline and direct measures of social motivation, we provide evidence that the Williams syndrome critical region regulates social motivation along with motor and anxiety phenotypes, but that Gtf2ird1 complementation is not sufficient to rescue most of these traits, and duplication does not decrease social motivation. However, Gtf2ird1 complementation does rescue light-aversive behavior and performance on select sensorimotor tasks, perhaps indicating a role for this gene in sensory processing or integration.

Extensive characterization of a Williams Syndrome murine model shows Gtf2ird1 -mediated rescue of select sensorimotor tasks, but no effect on enhanced social behavior

Williams Syndrome is a rare neurodevelopmental disorder exhibiting cognitive and behavioral abnormalities, including increased social motivation, risk of anxiety and specific phobias along with perturbed motor function. Williams Syndrome is caused by a microdeletion of 26-28 genes on chromosome 7, including GTF2IRD1 , which encodes a transcription factor suggested to play a role in the behavioral profile of Williams Syndrome. Duplications of the full region also lead to frequent autism diagnosis, social phobias, and language delay. Thus, genes in the region appear to regulate social motivation in a dose-sensitive manner. A 'Complete Deletion' mouse, heterozygously eliminating the syntenic Williams Syndrome region, has been deeply characterized for cardiac phenotypes, but direct measures of social motivation have not been assessed. Furthermore, the role of Gtf2ird1 in these behaviors has not been addressed in a relevant genetic context. Here, we have generated a mouse overexpressing Gtf2ird1 , which can be used both to model duplication of this gene alone and to rescue Gtf2ird1 expression in the Complete Deletion mice. Using a comprehensive behavioral pipeline and direct measures of social motivation, we provide evidence that the Williams Syndrome Critical Region regulates social motivation along with motor and anxiety phenotypes, but that Gtf2ird1 complementation is not sufficient to rescue most of these traits, and duplication does not decrease social motivation. However, Gtf2ird1 complementation does rescue light-aversive behavior and performance on select sensorimotor tasks, perhaps indicating a role for this gene in sensory processing or integration.

Neonatal Anesthesia and dysregulation of the Epigenome

Each year, millions of infants and children are anesthetized for medical and surgical procedures. Yet, a substantial body of preclinical evidence suggests that anesthetics are neurotoxins that cause rapid and widespread apoptotic cell death in the brains of infant rodents and non-human primates. These animals have persistent impairments in cognition and behavior many weeks or months after anesthesia exposure, leading us to hypothesize that anesthetics do more than simply kill brain cells. Indeed, anesthetics cause chronic neuropathology in neurons that survive the insult, which then interferes with major aspects of brain development, synaptic plasticity, and neuronal function. Understanding the phenomenon of anesthesia-induced developmental neurotoxicity is of critical public health importance because clinical studies now report that anesthesia in human infancy is associated with cognitive and behavioral deficits. In our search for mechanistic explanations for why a young and pliable brain cannot fully recover from a relatively brief period of anesthesia, we have accumulated evidence that neonatal anesthesia can dysregulate epigenetic tags that influence gene transcription such as histone acetylation and DNA methylation. In this review, we briefly summarize the phenomenon of anesthesia-induced developmental neurotoxicity. We then discuss chronic neuropathology caused by neonatal anesthesia, including disturbances in cognition, socio-affective behavior, neuronal morphology, and synaptic plasticity. Finally, we present evidence of anesthesia-induced genetic and epigenetic dysregulation within the developing brain that may be transmitted intergenerationally to anesthesia-naïve offspring.

Gtf2i and Gtf2ird1 mutation do not account for the full phenotypic effect of the Williams syndrome critical region in mouse models

Williams syndrome (WS) is a neurodevelopmental disorder caused by a 1.5-1.8 Mbp deletion on chromosome 7q11.23, affecting the copy number of 26-28 genes. Phenotypes of WS include cardiovascular problems, craniofacial dysmorphology, deficits in visual-spatial cognition and a characteristic hypersocial personality. There are still no genes in the region that have been consistently linked to the cognitive and behavioral phenotypes, although human studies and mouse models have led to the current hypothesis that the general transcription factor 2 I family of genes, GTF2I and GTF2IRD1, are responsible. Here we test the hypothesis that these two transcription factors are sufficient to reproduce the phenotypes that are caused by deletion of the WS critical region (WSCR). We compare a new mouse model with loss of function mutations in both Gtf2i and Gtf2ird1 to an established mouse model lacking the complete WSCR. We show that the complete deletion (CD) model has deficits across several behavioral domains including social communication, motor functioning and conditioned fear that are not explained by loss of function mutations in Gtf2i and Gtf2ird1. Furthermore, transcriptome profiling of the hippocampus shows changes in synaptic genes in the CD model that are not seen in the double mutants. Thus, we have thoroughly defined a set of molecular and behavioral consequences of complete WSCR deletion and shown that genes or combinations of genes beyond Gtf2i and Gtf2ird1 are necessary to produce these phenotypic effects.

Sex differences in neurodevelopmental abnormalities caused by early-life anaesthesia exposure: a narrative review

Exposure to anaesthetic drugs during the fetal or neonatal period induces widespread neuronal apoptosis in the brains of rodents and non-human primates. Hundreds of published preclinical studies and nearly 20 clinical studies have documented cognitive and behavioural deficits many months or years later, raising the spectre that early life anaesthesia exposure is a long-term, perhaps permanent, insult that might affect the quality of life of millions of humans. Although the phenomenon of anaesthesia-induced developmental neurotoxicity is well characterised, there are important and lingering questions pertaining to sex differences and neurodevelopmental sequelae that might occur differentially in females and males. We review the relevant literature on sex differences in the field of anaesthesia-induced developmental neurotoxicity, and present an emerging pattern of potential sex-dependent neurodevelopmental abnormalities in rodent models of human infant anaesthesia exposure.

Exposure to Morphine and Caffeine Induces Apoptosis and Mitochondrial Dysfunction in a Neonatal Rat Brain

Background: Preterm infants experience rapid brain growth during early post-natal life making them vulnerable to drugs acting on central nervous system. Morphine is administered to premature neonates for pain control and caffeine for apnea of prematurity. Simultaneous use of morphine and caffeine is common in the neonatal intensive care unit. Prior studies have shown acute neurotoxicity with this combination, however, little information is available on the mechanisms mediating the neurotoxic effects. The objective of this study was to determine the effects of morphine and caffeine, independently and in combination on mitochondrial dysfunction (Drp1 and Mfn2), neural apoptosis (Bcl-2, Bax, and cell damage) and endothelin (ET) receptors (ET_A and ET_B) in neonatal rat brain. Methods: Male and female rat pups were grouped separately and were divided into four different subgroups on the basis of treatments-saline (Control), morphine (MOR), caffeine (CAFF), and morphine + caffeine (M+C) treatment. Pups in MOR group were injected with 2 mg/kg morphine, CAFF group received 100 mg/kg caffeine, and M+C group received both morphine (2 mg/kg) and caffeine (100 mg/kg), subcutaneously on postnatal days (PND) 3-6. Pups were euthanized at PND 7, 14, or 28. Brains were isolated and analyzed for mitochondrial dysfunction, apoptosis markers, cell damage, and ET receptor expression via immunofluorescence and western blot analyses. Results: M+C showed a significantly higher expression of Bax compared to CAFF or MOR alone at PND 7, 14, 28 in female pups (p < 0.05) and at PND 7, 14 in male pups (p < 0.05). Significantly (p < 0.05) increased expression of Drp1, Bax, and suppressed expression of Mfn2, Bcl-2 at PND 7, 14, 28 in all the treatment groups compared to the control was observed in both genders. No significant difference in the expression of ET_A and ET_B receptors in male or female pups was seen at PND 7, 14, and 28. Conclusion: Concurrent use of morphine and caffeine during the first week of life increases apoptosis and cell damage in the developing brain compared to individual use of caffeine and morphine.

Caffeine Augments Anesthesia Neurotoxicity in the Fetal Macaque Brain

Caffeine is the most frequently used medication in premature infants. It is the respiratory stimulant of choice for apnea associated with prematurity and has been called the silver bullet in neonatology because of many proven benefits and few known risks. Research has revealed that sedative/anesthetic drugs trigger apoptotic death of neurons and oligodendrocytes in developing mammalian brains. Here we evaluated the influence of caffeine on the neurotoxicity of anesthesia in developing nonhuman primate brains. Fetal macaques (n = 7–8/group), at a neurodevelopmental age comparable to premature human infants, were exposed in utero for 5 hours to no drug (control), isoflurane, or isoflurane + caffeine and examined for evidence of apoptosis. Isoflurane exposure increased apoptosis 3.3 fold for neurons and 3.4 fold for oligodendrocytes compared to control brains. Isoflurane + caffeine caused neuronal apoptosis to increase 8.0 fold compared to control levels but did not augment oligoapoptosis. Neuronal death was particularly pronounced in the basal ganglia and cerebellum. Higher blood levels of caffeine within the range considered therapeutic and safe for human infants correlated with increased neuroapoptosis. Caffeine markedly augments neurotoxicity of isoflurane in the fetal macaque brain and challenges the assumption that caffeine is safe for premature infants.

Using animal models to evaluate the functional consequences of anesthesia during early neurodevelopment

Fifteen years ago Olney and colleagues began using animal models to evaluate the effects of anesthetic and sedative agents (ASAs) on neurodevelopment. The results from ongoing studies indicate that, under certain conditions, exposure to these drugs during development induces an acute elevated apoptotic neurodegenerative response in the brain and long-term functional impairments. These animal models have played a significant role in bringing attention to the possible adverse effects of exposing the developing brain to ASAs when few concerns had been raised previously in the medical community. The apoptotic degenerative response resulting from neonatal exposure to ASAs has been replicated in many studies in both rodents and non-human primates, suggesting that a similar effect may occur in humans. In both rodents and non-human primates, significantly increased levels of apoptotic degeneration are often associated with functional impairments later in life. However, behavioral deficits following developmental ASA exposure have not been consistently reported even when significantly elevated levels of apoptotic degeneration have been documented in animal models. In the present work, we review this literature and propose a rodent model for assessing potential functional deficits following neonatal ASA exposure with special reference to experimental design and procedural issues. Our intent is to improve test sensitivity and replicability for detecting subtle behavioral effects, and thus enhance the translational significance of ASA models.

Prevalence of xenobiotic substances in first-trimester blood samples from Danish pregnant women: a cross-sectional study

OBJECTIVE

The aim of this study was to investigate the prevalence of xenobiotic substances, such as caffeine, nicotine and illicit drugs (eg, cannabis and cocaine), in blood samples from first-trimester Danish pregnant women unaware of the screening.

DESIGN

A cross-sectional study examined 436 anonymised residual blood samples obtained during 2014 as part of the nationwide prenatal first-trimester screening programme. The samples were analysed by ultra performance liquid chromatography with high-resolution time-of-flight mass spectrometry.

SETTING

An antenatal clinic in a Danish city with 62 000 inhabitants, where >95% of pregnant women joined the screening programme.

PRIMARY AND SECONDARY OUTCOME MEASURES

The prevalence and patterns of caffeine, nicotine, medication and illicit drug intake during the first trimester of pregnancy.

RESULTS

The prevalence of prescription and over-the-counter drug detection was 17.9%, including acetaminophen (8.9%) and antidepressants (3.0%), of which citalopram (0.9%) was the most frequent. The prevalence of illegal drugs, indicators of smoking (nicotine/cotinine) and caffeine was 0.9%, 9.9%, and 76.4%, respectively. Only 17.4% of women had no substance identified in their sample.

CONCLUSIONS

This study emphasises the need for further translational studies investigating lifestyle habits during pregnancy, as well as the underlying molecular mechanisms through which xenobiotic substances may affect placental function and fetal development.

Caffeine combined with sedative/anesthetic drugs triggers widespread neuroapoptosis in a mouse model of prematurity

OBJECTIVES

Caffeine (CAF) and sedative/anesthetic drugs (SADs) are often coadministered to premature infants in the neonatal intensive care unit (NICU). While SAD neurotoxicity in the developing brain is well established, it is not fully clear whether CAF interacts with SADs and whether this interaction is detrimental. Using a mouse model of prematurity, we hypothesized that CAF would increase apoptotic neurotoxicity when coadministered with SADs.

METHODS

Postnatal day 3 mice were treated with vehicle or 80 mg/kg CAF prior to challenge with 6 mg/kg midazolam, 40 mg/kg ketamine, or 40 μg/kg fentanyl. Six hours later, pups were sacrificed for activated caspase 3 (AC3) immunohistochemistry, and number of AC3 positive cells per mm³ throughout neocortex, hippocampus, caudate, thalamus, and colliculi was analyzed.

RESULTS

CAF caused a statistically significant increase in AC3 positive cells when coadministered with midazolam (p = 0.002), ketamine (p = 0.014), or fentanyl (p < 0.001). Our composite dataset suggests that the addition of CAF to these SADs has a supra-additive effect, causing more neurotoxicity than expected.

CONCLUSIONS

CAF may augment the neurotoxic action of SADs indicated for neonatal sedation/anesthesia in the NICU by triggering widespread apoptosis in the developing brains of premature infants.

Adoptive Autophagy Activation: a Much-Needed Remedy Against Chemical Induced Neurotoxicity/Developmental Neurotoxicity

The profound significance of autophagy as a cell survival mechanism under conditions of metabolic stress is a well-proven fact. Nearly a decade-long research in this area has led scientists to unearth various roles played by autophagy other than just being an auto cell death mechanism. It is implicated as a vital cell survival pathway for clearance of all the aberrant cellular materials in case of cellular injury, metastasis, disease states, cellular stress, neurodegeneration and so on. In this review, we emphasise the critical role of autophagy in the environmental stressors-induced neurotoxicity and its therapeutic implications for the same. We also attempt to shed some light on the possible protective role of autophagy in developmental neurotoxicity (DNT) which is a rapidly growing health issue of the human population at large and hence a point of rising concern amongst researchers. The intimate association between DNT and neurodegenerative disorders strongly indicates towards adopting autophagy activation as a much-needed remedy for DNT.

Surgery and neurodevelopmental outcome of very low-birth-weight infants

IMPORTANCE

Reduced death and neurodevelopmental impairment among infants is a goal of perinatal medicine.

OBJECTIVE

To assess the association between surgery during the initial hospitalization and death or neurodevelopmental impairment of very low-birth-weight infants.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort analysis was conducted of patients enrolled in the National Institute of Child Health and Human Development Neonatal Research Network Generic Database from 1998 through 2009 and evaluated at 18 to 22 months' corrected age. Twenty-two academic neonatal intensive care units participated. Inclusion criteria were birth weight 401 to 1500 g, survival to 12 hours, and availability for follow-up. A total of 12 111 infants were included in analyses.

EXPOSURES

Surgical procedures; surgery also was classified by expected anesthesia type as major (general anesthesia) or minor (nongeneral anesthesia).

MAIN OUTCOMES AND MEASURES

Multivariable logistic regression analyses planned a priori were performed for the primary outcome of death or neurodevelopmental impairment and for the secondary outcome of neurodevelopmental impairment among survivors. Multivariable linear regression analyses were performed as planned for the adjusted mean scores of the Mental Developmental Index and Psychomotor Developmental Index of the Bayley Scales of Infant Development, Second Edition, for patients born before 2006.

RESULTS

A total of 2186 infants underwent major surgery, 784 had minor surgery, and 9141 infants did not undergo surgery. The risk-adjusted odds ratio of death or neurodevelopmental impairment for all surgery patients compared with those who had no surgery was 1.29 (95% CI, 1.08-1.55). For patients who had major surgery compared with those who had no surgery, the risk-adjusted odds ratio of death or neurodevelopmental impairment was 1.52 (95% CI, 1.24-1.87). Patients classified as having minor surgery had no increased adjusted risk. Among survivors who had major surgery compared with those who had no surgery, the adjusted risk of neurodevelopmental impairment was greater and the adjusted mean Bayley scores were lower.

CONCLUSIONS AND RELEVANCE

Major surgery in very low-birth-weight infants is independently associated with a greater than 50% increased risk of death or neurodevelopmental impairment and of neurodevelopmental impairment at 18 to 22 months' corrected age. The role of general anesthesia is implicated but remains unproven.