Perinatal Fentanyl Exposure Leads to Long-Lasting Impairments in Somatosensory Circuit Function and Behavior

Prenatal exposure to methadone or buprenorphine alters transcriptional networks associated with synaptic signaling in newborn rats

While the use of methadone or buprenorphine during pregnancy is beneficial for the mother's health compared to illicit opioid use, prenatal exposure to these medications may have adverse consequences for the unborn child. However, the underlying molecular mechanisms of prenatal opioid exposure on neurodevelopment remain poorly understood. Hence, this study aimed to investigate gene expression changes, focusing on synapse-related genes, in cerebral tissue from newborn rats prenatally exposed to methadone or buprenorphine. Female Sprague-Dawley rats were exposed to methadone (10 mg/kg/day), buprenorphine (1 mg/kg/day), or sterile water through osmotic minipumps during pregnancy. Total RNA was isolated from the cerebrum on postnatal day 2 and analyzed using RNA-sequencing. Analyses of differentially expressed genes (DEGs) and enriched biological processes were conducted to compare the gene expression profiles between treatment groups within each sex. Prenatal buprenorphine exposure resulted in 598 DEGs (333 up- and 265 downregulated) in males and 175 (75 up- and 100 downregulated) in females, while prenatal methadone exposure resulted in 335 DEGs (224 up- and 111 downregulated) in males and 201 (57 up- and 144 downregulated) in females. Gene ontology analyses demonstrated that enriched biological processes included synaptic signaling, immune responses, and apoptosis. Analysis of the DEGs using the synapse database SynGO revealed that males prenatally exposed to buprenorphine displayed the highest number of enriched synapse-related biological process terms. Understanding gene expression changes following prenatal methadone or buprenorphine exposure is crucial to uncover the mechanisms underlying behavioral alterations and to develop interventions to mitigate the impact of opioid exposure on neurodevelopment.

Reproductive and developmental toxicity assessment of HSK21542, a novel peripherally-restricted kappa opioid receptor agonist in rats and rabbits

HSK21542, a potent and peripherally-restricted kappa opioid receptor (KOR) agonist, is currently being developed to treat postoperative pain and pruritus. Given that conventional opioids (MOR agonists) are widely recognized for their toxicological impacts on the reproductive system and embryonic development, we evaluated the effects of HSK21542 accordingly. The results showed that HSK21542 did not influence male and female fertility or early embryonic development in rats. HSK21542 also did not show significant manifestations of pre- and post-natal development toxicity in rats. In the embryo-fetal developmental study, even though there was a 3.5 % increase in incidence of fetuses with incomplete ossification of thoracic vertebral centrum in the 4 mg/kg/day group, the plasma exposure of HSK21542 in rats at the no observed adverse effect level (NOAEL) was 82.3 times higher than that of human exposure at 1 μg/kg. On the other hand, exposure to HSK21542 during pregnancy in rabbits did not show any teratogenic risk, only causing a minor impact on bone ossification in fetuses. In conclusion, HSK21542 has a favorable safety profile with only minor effects on the embryo-fetal developmental outcomes.

Systemic barriers and stigma: Healthcare provider perspectives on perinatal and neonatal care in the fentanyl crisis

INTRODUCTION

The rise in fentanyl use during pregnancy has created new challenges in caring for women with opioid use disorders (OUD) and their infants with neonatal abstinence syndrome or neonatal opioid withdrawal syndrome (NAS/NOWS). Despite complexities in treating opioid-affected dyads, little research exists on healthcare workers' perspectives regarding fentanyl's impact on perinatal and neonatal care.

OBJECTIVES

Explore dynamic challenges fentanyl has brought to the care of perinatal women with OUD and their infants experiencing NAS/NOWS from healthcare providers' perspectives.

METHODS

Fifteen healthcare providers (neonatologists, OBGYNs, nurse practitioners, registered nurses, and pediatricians) from the Pacific Northwest completed an online qualitative survey with a mixture of Likert-type and open-ended questions. Reflexive thematic analysis was used to analyze open-ended responses.

RESULTS

Three themes emerged from provider data that reflect systemic failures in addressing the complex needs of perinatal women and their families and highlight challenges in implementation of evidence-based care: 1) Systemic Barriers to Perinatal and Infant Care, 2) Impact of Increasing Polysubstance Use on Neonates and Mothers, and 3) Stigma and Judgment from Healthcare Providers toward Perinatal Women with Substance Use Disorders.

CONCLUSIONS

Themes reflected how broad and interconnected systemic issues contribute to inadequate care and support for mothers and newborns in the context of rising fentanyl and polysubstance use. Themes echoed the root of the problems lies in systemic failures-issues within the healthcare system, societal attitudes, and policy frameworks that collectively fail to meet the complex and evolving needs of families affected by the ever-changing landscape of substance use.

Population Pharmacokinetic of Epidural Sufentanil in Labouring Women: A Multicentric, Prospective, Observational Study

Purpose

The effects of sufentanil-ropivacaine combination on the parturient women and the course of labor have been well documented. However, there is little information regarding the time-dependent pharmacokinetic characteristics of sufentanil after epidural administration in laboring women. We aimed to develop a population PK model for epidural sufentanil in laboring women to evaluate the sufentanil placental transfer quantitatively.

Patients and Methods

Forty-one participants who underwent epidural labor analgesia were recruited into this study. Patients received a continuous epidural infusion of sufentanil 0.3 µg/mL with ropivacaine 0.1%. Maternal venous blood samples and umbilical venous blood samples were collected for population PK analysis. The trends of sufentanil blood concentrations in the mothers and umbilical cord were predicted by the model.

Results

Sufentanil disposition after continuous epidural administration in laboring women followed a two-compartment pharmacokinetic model. The estimated sufentanil central clearance (CL), central volume of distribution (V1), clearance between central compartment and umbilical cord compartment (CL2), and umbilical cord volume of distribution (V2) were 176 L/h, 519 L, 0.0134 L/h, and 0.187 L. The absolute level of sufentanil in placental circulation is low after epidural administration. A slow decline in placental sufentanil concentration was predicted by the final PK model after epidural infusion was discontinued.

Conclusion

A slow decline in placental sufentanil concentration is predicted by the final two-compartment PK model after epidural infusion was discontinued. This suggests that very large doses of epidural sufentanil should be avoided during labor analgesia.

Trial Registration

https://www.chictr.org.cn, No: ChiCTR1800018810.

Evaluating maternal drug use disparities, risk factors and outcomes in Northeast Arkansas: a pre, during, and post-COVID-19 pandemic analysis

INTRODUCTION

The use of addictive substances remains a major health problem in the U.S. An increase in drug overdose and mortality was observed during the COVID-19 pandemic, especially in underserved populations. This surge also impacted pregnant women especially with the use of marijuana (THC) and opioids.

METHODS

Retrospective study analyzing mother-infant dyads with reported Meconium Drug Screen (MDS) results, from January 2018 through April 2023 at a reference hospital serving an urban and rural area of Arkansas. Due to the absence of universal screening, the prevalence of drug use was variable during the study period. An adjusted monthly positive rate (AMPR) was calculated by considering the expected number of positive MDS screenings per month and adjusting it based on the screening rate per month and the monthly birth count.

RESULTS

Among 8,030 live births, 957 dyads were included in the analysis, with 47% (N = 450) of infants testing positive for at least one substance. Of these, 64.2%, 11.1%, and 6.7% were positive for THC, amphetamines, and opioids, respectively; and 17.8% tested positive for more than one substance. Infants with a positive MDS (MDS+) had significantly lower weight, height and head circumference with higher preterm rates and longer hospital stays. Mothers who smoked during pregnancy were more than twice as likely to have an MDS + result than those who did not (OR 2.39 (95% CI: 1.34-3.02), and most were from metropolitan areas (73%) or white (67%). The adjusted MDS + rate or AMPR significantly increased over the study period from 6.8% (January 2018) to 7.4% (April 2023). However, the COVID-19 pandemic did not significantly impact these rates. Compared to amphetamines and opioids, THC usage significantly increased during the study period and this increase was more pronounced after the state's legalization of THC.

CONCLUSION

Maternal substance use, predominantly THC, continues to increase, particularly following its legalization. Infants who were MDS + presented adverse neonatal outcomes, with the majority of the mothers being white and from urban settings. Maternal self-reported smoking was associated with increased usage of other substances. Racial disparities were observed during the study, underscoring the need for universal drug testing and targeted interventions.

Beyond a simple cause and effect relationship: Exploring the long-term outcomes of children prenatally exposed to opioids and other substances

The long-term outcomes of children exposed to opioids and other substances in utero, specifically those diagnosed with Neonatal Abstinence Syndrome (NAS), present a complex interaction of different factors. First, NAS and its clinical presentation will be defined, then summarized will be an overview of NAS prevalence, recent trends, and significance of NAS in the context of the rising synthetic opioid and polysubstance use. Highlighted will also be the identified risk factors for NAS, especially regarding the role of environmental and psychosocial stressors during pregnancy. Finally, reviewed will be the existing NAS literature, including its gaps and limitations, and suggested recommendations for future research and policy considerations for improving care for children and families impacted by NAS.

Inhibition of post-lanosterol biosynthesis by fentanyl: potential implications for Fetal Fentanyl Syndrome (FFS)

A recent study discovered a novel, complex developmental disability syndrome, most likely caused by maternal fentanyl use disorder. This Fetal Fentanyl Syndrome (FFS) is biochemically characterized by elevated 7-dehydrocholesterol (7-DHC) levels in neonates, raising the question if fentanyl inhibition of the dehydrocholesterol reductase 7 (DHCR7) enzyme is causal for the emergence of the pathophysiology and phenotypic features of FFS. To test this hypothesis, we undertook a series of experiments on Neuro2a cells, primary mouse neuronal and astrocytic cultures, and human dermal fibroblasts (HDFs) with DHCR7+/+ and DHCR7+/- genotype. Our results revealed that in vitro exposure to fentanyl disrupted sterol biosynthesis across all four in vitro models. The sterol biosynthesis disruption by fentanyl was complex, and encompassed the majority of post-lanosterol intermediates, including elevated 7-DHC and decreased desmosterol (DES) levels across all investigated models. The overall findings suggested that maternal fentanyl use in the context of an opioid use disorder leads to FFS in the developing fetus through a strong disruption of the whole post-lanosterol pathway that is more complex than a simple DHCR7 inhibition. In follow-up experiments we found that heterozygous DHCR7+/- HDFs were significantly more susceptible to the sterol biosynthesis inhibitory effects of fentanyl than wild-type DHCR7+/+ fibroblasts. These data suggest that DHCR7+/- heterozygosity of mother and/or developing child (and potentially other sterol biosynthesis genes), when combined with maternal fentanyl use disorder, might be a significant contributory factor to the emergence of FFS in the exposed offspring. In a broader context, we believe that evaluation of new and existing medications for their effects on sterol biosynthesis should be an essential consideration during drug safety determinations, especially in pregnancy.

A Review of the Literature on Episodes of Acute Fentanyl Intoxication in Pediatric Age and Toxicological Applications

Fentanyl is an opioid with powerful analgesic effects and a high speed of action. Due to its pharmacological properties, this molecule has therapeutic application as an anesthetic in surgery or as palliative therapy for cancer patients. Unfortunately, in recent years, the easy availability of this substance, the low cost and the illegal online market have favored the large-scale diffusion of fentanyl. Fentanyl is available in different forms, including nasal spray, oral patches, soluble capsules, aerosol or the new version of fentanyl mixed with other drugs, making its use very widespread. Subjects of various ages are involved in fentanyl consumption, including minors that have not yet reached adolescence. In this work, we performed a literature review using the search engines PubMed NCBI and SCOPUS regarding episodes of acute fentanyl intoxication occurring in those of a pediatric age using the Mesh Terms "fentanyl" AND "overdose" AND "children". The inclusion criteria were English papers published in the last 10 years regarding the cases of children under the age of 10. We evaluated the most frequent methods of intake and the circumstances of such episodes. In cases of death, we analyzed the autopsy, the toxicological findings and the investigations carried out. The review results show that in this age group (under < 10 y.o. s), it is possible to identify the risk factors for fentanyl intake, such as the presence of this molecule within the family unit due to drug addiction or medical therapy. The results also demonstrate a significant risk of underestimation of this phenomenon, since the molecule is often not investigated through adequate toxicological analysis. These results, therefore, suggest always carrying out toxicological investigations in the case of suspected fentanyl intoxication, both on patients or cadavers. The investigations must always include a urinary screening for opiates, and the request for a second level analysis with molecule dosage in cases of positivity or in cases of strong suspicion for assumption. In cases of intoxication in a family context of drug addiction, it is necessary to investigate the chronicity of the intake through hair analysis and evaluate the possible co-administration of other drugs. In conclusion, we suggest a protocol, applicable both on patients or cadavers, which can be useful for physicians and forensic pathologists in order to promptly identify these cases and allow for the reporting of them to the judicial authorities with the adoption of strict prevention and control measures.

Trajectories of brain and behaviour development in the womb, at birth and through infancy

Birth is often seen as the starting point for studying effects of the environment on human development, with much research focused on the capacities of young infants. However, recent imaging advances have revealed that the complex behaviours of the fetus and the uterine environment exert influence. Birth is now viewed as a punctuate event along a developmental pathway of increasing autonomy of the child from their mother. Here we highlight (1) increasing physiological autonomy and perceptual sensitivity in the fetus, (2) physiological and neurochemical processes associated with birth that influence future behaviour, (3) the recalibration of motor and sensory systems in the newborn to adapt to the world outside the womb and (4) the effect of the prenatal environment on later infant behaviours and brain function. Taken together, these lines of evidence move us beyond nature-nurture issues to a developmental human lifespan view beginning within the womb.

Neurobehavioral Characterization of Perinatal Oxycodone-Exposed Offspring in Early Adolescence

The opioid epidemic has received considerable attention, but the impact on perinatal opioid-exposed (POE) offspring remains underexplored. This study addresses the emerging public health challenge of understanding and treating POE children. We examined two scenarios using preclinical models: offspring exposed to oxycodone (OXY) in utero (IUO) and acute postnatal OXY (PNO). We hypothesized exposure to OXY during pregnancy primes offspring for neurodevelopmental deficits and severity of deficits is dependent on timing of exposure. Notable findings include reduced head size and brain weight in offspring. Molecular analyses revealed significantly lower levels of inflammasome-specific genes in the prefrontal cortex (PFC). Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA) highlighted the enrichment of genes associated with mitochondrial and synapse dysfunction in POE offspring. Western blot analysis validated IPA predictions of mitochondrial dysfunction in PFC-derived synaptosomes. Behavioral studies identified significant social deficits in POE offspring. This study presents the first comparative analysis of acute PNO- and IUO-offspring during early adolescence finding acute PNO-offspring have considerably greater deficits. The striking difference in deficit severity in acute PNO-offspring suggests that exposure to opioids in late pregnancy pose the greatest risk for offspring well-being.

Advances in animal models of prenatal opioid exposure

Neonatal opioid withdrawal syndrome (NOWS) is a growing public health concern. The complexity of in utero opioid exposure in clinical studies makes it difficult to investigate underlying mechanisms that could ultimately inform early diagnosis and treatments. Clinical studies are unable to dissociate the influence of maternal polypharmacy or the environment from direct effects of in utero opioid exposure, highlighting the need for effective animal models. Early animal models of prenatal opioid exposure primarily used the prototypical opioid, morphine, and opioid exposure that was often limited to a narrow period during gestation. In recent years, the number of preclinical studies has grown rapidly. Newer models utilize both prescription and nonprescription opioids and vary the onset and duration of opioid exposure. In this review, we summarize novel prenatal opioid exposure models developed in recent years and attempt to reconcile results between studies while critically identifying gaps within the current literature.

Opioid-induced dysbiosis of maternal gut microbiota during gestation alters offspring gut microbiota and pain sensitivity

There has been a rapid increase in neonates born with a history of prenatal opioid exposure. How prenatal opioid exposure affects pain sensitivity in offspring is of interest, as this may perpetuate the opioid epidemic. While few studies have reported hypersensitivity to thermal pain, potential mechanisms have not been described. This study posits that alterations in the gut microbiome may underly hypersensitivity to pain in prenatally methadone-exposed 3-week-old male offspring, which were generated using a mouse model of prenatal methadone exposure. Fecal samples collected from dams and their offspring were subjected to 16s rRNA sequencing. Thermal and mechanical pain were assessed using the tail flick and Von Frey assays. Transcriptomic changes in whole brain samples of opioid or saline-exposed offspring were investigated using RNA-sequencing, and midbrain sections from these animals were subjected to qPCR profiling of genes related to neuropathic and inflammatory pain pathways. Prenatal methadone exposure increased sensitivity to thermal and mechanical pain and elevated serum levels of IL-17a. Taxonomical analysis revealed that prenatal methadone exposure resulted in significant alterations in fecal gut microbiota composition, including depletion of Lactobacillus, Bifidobacterium, and Lachnospiracea sp and increased relative abundance of Akkermansia, Clostridium sensu stricto 1, and Lachnoclostridium. Supplementation of the probiotic VSL#3 in dams rescued hypersensitivity to thermal and mechanical pain in prenatally methadone-exposed offspring. Similarly, cross-fostering prenatally methadone-exposed offspring to control dams also attenuated hypersensitivity to thermal pain in opioid-exposed offspring. Modulation of the maternal and neonatal gut microbiome with probiotics resulted in transcriptional changes in genes related to neuropathic and immune-related signaling in whole brain and midbrain samples of prenatally methadone-exposed offspring. Together, our work provides compelling evidence of the gut-brain-axis in mediating pain sensitivity in prenatally opioid-exposed offspring.

Opioid, methamphetamine, and polysubstance use: perinatal outcomes for the mother and infant

The escalation in opioid pain relief (OPR) medications, heroin and fentanyl, has led to an increased use during pregnancy and a public health crisis. Methamphetamine use in women of childbearing age has now eclipsed the use of cocaine and other stimulants globally. Recent reports have shown increases in methamphetamine are selective to opioid use, particularly in rural regions in the US. This report compares the extent of our knowledge of the perinatal outcomes of OPRs, heroin, fentanyl, two long-acting substances used in the treatment of opioid use disorders (buprenorphine and methadone), and methamphetamine. The methodological limitations of the current research are examined, and two important initiatives that will address these limitations are reviewed. Current knowledge of the perinatal effects of short-acting opioids, OPRs, heroin, and fentanyl, is scarce. Most of what we know about the perinatal effects of opioids comes from research on the long-acting opioid agonist drugs used in the treatment of OUDs, methadone and buprenorphine. Both have better perinatal outcomes for the mother and newborn than heroin, but the uptake of these opioid substitution programs is poor (<50%). Current research on perinatal outcomes of methamphetamine is limited to retrospective epidemiological studies, chart reviews, one study from a treatment center in Hawaii, and the US and NZ cross-cultural infant Development, Environment And Lifestyle IDEAL studies. Characteristics of pregnant individuals in both opioid and MA studies were associated with poor maternal health, higher rates of mental illness, trauma, and poverty. Infant outcomes that differed between opioid and MA exposure included variations in neurobehavior at birth which could complicate the diagnosis and treatment of neonatal opioid withdrawal (NOWs). Given the complexity of OUDs in pregnant individuals and the increasing co-use of these opioids with MA, large studies are needed. These studies need to address the many confounders to perinatal outcomes and employ neurodevelopmental markers at birth that can help predict long-term neurodevelopmental outcomes. Two US initiatives that can provide critical research and treatment answers to this public health crisis are the US Environmental influences on Child Health Outcomes (ECHO) program and the Medication for Opioid Use Disorder During Pregnancy Network (MAT-LINK).

Developmental outcomes with perinatal exposure (DOPE) to prescription opioids

Researchers have found considerable evidence in the past 20 years that perinatal opioid exposure leads to an increased risk of developmental disorders in offspring that persist into adulthood. The use of opioids to treat pain concerning pregnancy, delivery, and postpartum complications has been rising. As a result, communities have reported a 300-400 % increase in Neonatal Opioid Withdrawal Syndrome (NOWS). NOWS represents the initial stage of several behavioral, phenotypic, and synaptic deficits. This review article summarizes the Developmental Outcomes of Perinatal Exposure (DOPE) to prescription opioids. Moreover, we also seek to connect these findings to clinical research that describes DOPE at multiple stages of life. Since specific mechanisms that underlie DOPE remain unclear, this article aims to provide a framework for conceptualizing across all ages and highlight the implications they may have for longevity.

Transcriptomic profiling of reward and sensory brain areas in perinatal fentanyl exposed juvenile mice

Use of the synthetic opioid fentanyl increased ~300% in the last decade, including among women of reproductive ages. Adverse neonatal outcomes and long-term behavioral disruptions are associated with perinatal opioid exposure. Our previous work demonstrated that perinatal fentanyl exposed mice displayed enhanced negative affect and somatosensory circuit and behavioral disruptions during adolescence. However, little is known about molecular adaptations across brain regions that underlie these outcomes. We performed RNA sequencing across three reward and two sensory brain areas to study transcriptional programs in perinatal fentanyl exposed juvenile mice. Pregnant dams received 10 μg/ml fentanyl in the drinking water from embryonic day 0 (E0) through gestational periods until weaning at postnatal day 21 (P21). RNA was extracted from nucleus accumbens (NAc), prelimbic cortex (PrL), ventral tegmental area (VTA), somatosensory cortex (S1) and ventrobasal thalamus (VBT) from perinatal fentanyl exposed mice of both sexes at P35. RNA sequencing was performed, followed by analysis of differentially expressed genes (DEGs) and gene co-expression networks. Transcriptome analysis revealed DEGs and gene modules significantly associated with exposure to perinatal fentanyl in a sex-wise manner. The VTA had the most DEGs, while robust gene enrichment occurred in NAc. Genes enriched in mitochondrial respiration were pronounced in NAc and VTA of perinatal fentanyl exposed males, extracellular matrix (ECM) and neuronal migration enrichment were pronounced in NAc and VTA of perinatal fentanyl exposed males, while genes associated with vesicular cycling and synaptic signaling were markedly altered in NAc of perinatal fentanyl exposed female mice. In sensory areas from perinatal fentanyl exposed females, we found alterations in mitochondrial respiration, synaptic and ciliary organization processes. Our findings demonstrate distinct transcriptomes across reward and sensory brain regions, with some showing discordance between sexes. These transcriptome adaptations may underlie structural, functional, and behavioral changes observed in perinatal fentanyl exposed mice.

Endogenous opiates and behavior: 2021

This paper is the forty-fourth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2021 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonizts and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Effects of neonatal fentanyl on late adolescent opioid-mediated behavior

Introduction

Because of the steady increase in the use of synthetic opioids in women of childbearing age, a large number of children are at risk of exposure to these drugs prenatally or postnatally through breast milk. While there is older literature looking at the effects of morphine and heroin, there are relatively few studies looking at the long-term effects of high-potency synthetic opioid compounds like fentanyl. Thus, in the present study, we assessed whether brief exposure to fentanyl in male and female rat pups during a period roughly equivalent to the third trimester of CNS development altered adolescent oral fentanyl self-administration and opioid-mediated thermal antinociception.

Methods

We treated the rats with fentanyl (0, 10, or 100 μg/kg sc) from postnatal day (PD) 4 to PD 9. The fentanyl was administered daily in two injections given 6 h apart. After the last injection on PD 9, the rat pups were left alone until either PD 40 where they began fentanyl self-administration training or PD 60 where they were tested for morphine- (0, 1.25, 2.5, 5, or 10 mg/kg) or U50,488- (0, 2.5, 5, 10, or 20 mg/kg) induced thermal antinociception.

Results

In the self-administration study, we found that female rats had more active nose pokes than male rats when receiving a fentanyl reward but not sucrose alone solution. Early neonatal fentanyl exposure did not significantly alter fentanyl intake or nose-poke response. In contrast, early fentanyl exposure did alter thermal antinociception in both male and female rats. Specifically, fentanyl (10 μg/kg) pre-treatment increased baseline paw-lick latencies, and the higher dose of fentanyl (100 μg/kg) reduced morphine-induced paw-lick latencies. Fentanyl pre-treatment did not alter U50,488-mediated thermal antinociception.

Conclusions

Although our exposure model is not reflective of typical human fentanyl use during pregnancy, our study does illustrate that even brief exposure to fentanyl during early development can have long-lasting effects on mu-opioid-mediated behavior. Moreover, our data suggest that females may be more susceptible to fentanyl abuse than males.

Prenatal Cafeteria Diet Primes Anxiety-like Behavior Associated to Defects in Volume and Diffusion in the Fimbria-fornix of Mice Offspring

Prenatal exposure to high-energy diets primes brain alterations that increase the risk of developing behavioral and cognitive failures. Alterations in the structure and connectivity of brain involved in learning and memory performance are found in adult obese murine models and in humans. However, the role of prenatal exposure to high-energy diets in the modulation of the brain's structure and function during cognitive decline remains unknown. We used female C57BL6 mice (n = 10) exposed to a high-energy diets (Cafeteria diet (CAF)) or Chow diet for 9 weeks (before, during and after pregnancy) to characterize their effect on brain structural organization and learning and memory performance in the offspring at two-month-old (n = 17). Memory and learning performance were evaluated using the Y-maze test including forced and spontaneous alternation, novel object recognition (NORT), open field and Barnes maze tests. We found no alterations in the short- or long-time spatial memory performance in male offspring prenatally exposed to CAF diet when compared to the control, but they increased time spent in the edges resembling anxiety-like behavior. By using deformation-based morphometry and diffusion tensor imaging analysis we found that male offspring exposed to CAF diet showed increased volume in primary somatosensory cortex and a reduced volume of fimbria-fornix, which correlate with alterations in its white matter integrity. Biological modeling revealed that prenatal exposure to CAF diet predicts low volume in the fimbria-fornix, which was associated with anxiety in the offspring. The findings suggest that prenatal exposure to high-energy diets prime brain structural alterations related to anxiety in the offspring.

Intrauterine and Neonatal Exposure to Opioids: Toxicological, Clinical, and Medico-Legal Issues

Opioids have a rapid transplacental passage (i.e., less than 60 min); furthermore, symptoms characterize the maternal and fetal withdrawal syndrome. Opioid withdrawal significantly impacts the fetus, inducing worse outcomes and a risk of mortality. Moreover, neonatal abstinence syndrome (NAS) follows the delivery, lasts up to 10 weeks, and requires intensive management. Therefore, the prevention and adequate management of NAS are relevant public health issues. This review aims to summarize the most updated evidence in the literature regarding toxicological, clinical, and forensic issues of intrauterine exposure to opioids to provide a multidisciplinary, evidence-based approach for managing such issues. Further research is required to standardize testing and to better understand the distribution of opioid derivatives in each specimen type, as well as the clinically relevant cutoff concentrations in quantitative testing results. A multidisciplinary approach is required, with obstetricians, pediatricians, nurses, forensic doctors and toxicologists, social workers, addiction specialists, and politicians all working together to implement social welfare and social services for the baby when needed. The healthcare system should encourage multidisciplinary activity in this field and direct suspected maternal and neonatal opioid intoxication cases to local referral centers.

Effects of prenatal opioid exposure on synaptic adaptations and behaviors across development

In this review, we focus on prenatal opioid exposure (POE) given the significant concern for the mental health outcomes of children with parents affected by opioid use disorder (OUD) in the view of the current opioid crisis. We highlight some of the less explored interactions between developmental age and sex on synaptic plasticity and associated behavioral outcomes in preclinical POE research. We begin with an overview of the rich literature on hippocampal related behaviors and plasticity across POE exposure paradigms. We then discuss recent work on reward circuit dysregulation following POE. Additional risk factors such as early life stress (ELS) could further influence synaptic and behavioral outcomes of POE. Therefore, we include an overview on the use of preclinical ELS models where ELS exposure during key critical developmental periods confers considerable vulnerability to addiction and stress psychopathology. Here, we hope to highlight the similarity between POE and ELS on development and maintenance of opioid-induced plasticity and altered opioid-related behaviors where similar enduring plasticity in reward circuits may occur. We conclude the review with some of the limitations that should be considered in future investigations. This article is part of the Special Issue on 'Opioid-induced addiction'.

Perinatal oxycodone exposure causes long-term sex-dependent changes in weight trajectory and sensory processing in adult mice

RATIONALE

In utero opioid exposure is associated with lower weight and a neonatal opioid withdrawal syndrome (NOWS) at birth, along with longer-term adverse neurodevelopmental outcomes and mood disorders. While NOWS is sometimes treated with continued opioids, clinical studies have not addressed if long-term neurobehavioral outcomes are worsened with continued postnatal exposure to opioids. In addition, pre-clinical studies comparing in utero only opioid exposure to continued post-natal opioid administration for withdrawal mitigation are lacking.

OBJECTIVES

Here, we sought to understand the impact of continued postnatal opioid exposure on long term behavioral consequences.

METHODS

We implemented a rodent perinatal opioid exposure model of oxycodone (Oxy) exposure that included Oxy exposure until birth (short Oxy) and continued postnatal opioid exposure (long Oxy) spanning gestation through birth and lactation.

RESULTS

Short Oxy exposure was associated with a sex-specific increase in weight gain trajectory in adult male mice. Long Oxy exposure caused an increased weight gain trajectory in adult males and alterations in nociceptive processing in females. Importantly, there was no evidence of long-term social behavioral deficits, anxiety, hyperactivity, or memory deficits following short or long Oxy exposure.

CONCLUSIONS

Our findings suggest that offspring with prolonged opioid exposure experienced some long-term sequelae compared to pups with opioid cessation at birth. These results highlight the potential long-term consequences of opioid administration as a mitigation strategy for clinical NOWS symptomology and suggest alternatives should be explored.