Maternally administered sustained-release naltrexone in rats affects offspring neurochemistry and behaviour in adulthood

The Safety of Alcohol Pharmacotherapies in Pregnancy: A Scoping Review of Human and Animal Research

BACKGROUND AND OBJECTIVE

Alcohol pharmacotherapies pose unknown teratogenic risks in pregnancy and are therefore recommended to be avoided. This limits treatment options for pregnant individuals with alcohol use disorders (AUD). The information on the safety of these medications during pregnancy is uncertain, prompting a scoping review. The objective of this review was to investigate available information on the safety of alcohol pharmacotherapies in pregnancy.

METHODS

Studies published between January 1990 and July 2023 were identified through searches in BIOSIS, Embase, PsycINFO and MEDLINE databases, using terms related to pregnancy and alcohol pharmacotherapies. The alcohol pharmacotherapies investigated were naltrexone, acamprosate, disulfiram, nalmefene, baclofen, gabapentin and topiramate. Studies were screened by two independent reviewers. Covidence software facilitated the management, screening and extraction of studies.

RESULTS

A total of 105 studies were included in the review (naltrexone: 21, acamprosate: 4, disulfiram: 3, baclofen: 3, nalmefene: 0, topiramate: 55, gabapentin: 32) with some studies investigating multiple medications. Studies investigating naltrexone's safety in pregnancy focussed on opioid use disorders, with limited evidence regarding its safety in the context of AUD. Despite concerns about higher rates of some pregnancy complications, studies generally indicate naltrexone as a safer option compared with opioid agonists or alcohol during pregnancy. Acamprosate was not clearly associated with adverse effects of exposure in pregnancy, with two pre-clinical studies suggesting potential neuroprotective properties. Disulfiram has a high risk of congenital anomalies when used in pregnancy, believed to be due to its mechanism of action. Prenatal topiramate has also been associated with an increased risk of congenital anomalies, particularly oral clefts. There were mixed results concerning the safety of prenatal gabapentin and little to no literature investigating the safety of baclofen or nalmefene during pregnancy.

CONCLUSIONS

There is insufficient research on the safety of alcohol pharmacotherapies in pregnancy. Despite this, given alcohol's teratogenic effects, naltrexone could be considered to help maintain abstinence in pregnant individuals with AUD, particularly when psychosocial treatments have failed.

M1 muscarinic receptor activation decreases alcohol consumption via a reduction in consummatory behavior

Muscarinic acetylcholine receptors (mAChRs) have been shown to mediate alcohol consumption and seeking. Both M₄ and M₅ mAChRs have been highlighted as potential novel treatment targets for alcohol use disorders (AUD). Similarly, M₁ mAChRs are expressed throughout reward circuitry, and their signaling has been implicated in cocaine consumption. However, whether the same effects are seen for alcohol consumption, or whether natural reward intake is inadvertently impacted is still unknown. To determine the role of M₁ mAChRs in alcohol consumption, we tested operant self-administration of alcohol under both fixed ratio (FR3) and progressive ratio (PR3-4) schedules. Enhancing M₁ mAChR signaling (via the M₁ PAM-Agonist PF-06767832, 1 mg/kg, i.p.) reduced operant alcohol consumption on a fixed schedule but had no effect on motivation to acquire alcohol. To determine whether these actions were specific to alcohol, we examined the effects of M₁ enhancement on natural reward (sucrose) self-administration. Systemic administration of PF-06767832 (1 mg/kg, i.p.) also reduced operant sucrose self-administration, suggesting the actions of the M₁ receptor may be non-selective across drug and natural rewards. Finally, to understand whether this reduction extended to natural consummatory behaviors, we assessed home cage standard chow and water consumption. M₁ enhancement via systemic PF-06767832 administration reduced food and water consumption. Together our results suggest the M₁ PAM-agonist, PF-06767832, non-specifically reduces consummatory behaviors that are not associated with motivational strength for the reward. These data highlight the need to further characterize M₁ agonists, PAMs, and PAM-agonists, which may have varying degrees of utility in the treatment of neuropsychiatric disorders including AUD.

Pharmacotherapies for the Treatment of Alcohol Use Disorders During Pregnancy: Time to Reconsider?

It is generally recommended that medications only be used in pregnancy where the potential harms to both the mother and foetus are outweighed by the potential benefits. Despite the known harms associated with alcohol consumption during pregnancy, the use of medication for the treatment of pregnant women with an alcohol use disorder (AUD) appears to be rare. This is likely due to the lack of available data regarding the safety of these medications in pregnancy. We reviewed the literature and weighed up the harms associated with alcohol use and AUD during pregnancy with the potential benefits of medications for AUD in pregnancy, including acamprosate, naltrexone and disulfiram. There is little published evidence to support the safety of medications for AUD in pregnancy. However, from the research available it is likely that only disulfiram has the potential to cause serious foetal harm. While further research is required, acamprosate and naltrexone do not appear to be associated with substantial risks of congenital malformations or other serious consequences. Given the potential risks associated with alcohol consumption during pregnancy, the use of acamprosate and naltrexone should be considered for the treatment of pregnant women with AUD based on the current evidence base, although more research is warranted.

Cocaine and amphetamine regulated transcript (CART) signalling in the central nucleus of the amygdala modulates stress-induced alcohol seeking

The central nucleus of the amygdala (CeA) is a key hub of the neural circuitry regulating alcohol and stress interactions. However, the exact neuronal populations that govern this interaction are not well defined. Here we examined the role of the neuropeptide cocaine and amphetamine regulated transcript (CART) within the CeA in stress-induced alcohol seeking. We found that CART-containing neurons are predominantly expressed in the capsular/lateral division of the CeA and are a subpopulation of protein kinase Cδ (PKCδ) cells, distinct from corticotrophin releasing factor (CRF)-expressing cells. Both stress (yohimbine) and stress-induced alcohol seeking activated CART cells within the CeA, while neutralisation of endogenous CeA CART signalling (via antibody administration) attenuated stress-induced alcohol, but not sucrose seeking. Further, blocking CART signalling within the CeA did not alter the motivation to obtain and consume alcohol but did attenuate stressor-induced anxiety-like behaviour during abstinence from alcohol. Together, these data identify CeA CART cells as a subpopulation of PKCδ cells that influence stress × alcohol interactions and mediate stress-induced alcohol seeking behaviours.

Acetylcholine Muscarinic M4 Receptors as a Therapeutic Target for Alcohol Use Disorder: Converging Evidence From Humans and Rodents

BACKGROUND

Alcohol use disorder (AUD) is a major socioeconomic burden on society, and current pharmacotherapeutic treatment options are inadequate. Aberrant alcohol use and seeking alters frontostriatal function.

METHODS

We performed genome-wide RNA sequencing and subsequent quantitative polymerase chain reaction and receptor binding validation in the caudate-putamen of human AUD samples to identify potential therapeutic targets. We then back-translated our top candidate targets into a rodent model of long-term alcohol consumption to assess concordance of molecular adaptations in the rat striatum. Finally, we adopted rat behavioral models of alcohol intake and seeking to validate a potential therapeutic target.

RESULTS

We found that G protein-coupled receptors were the top canonical pathway differentially regulated in individuals with AUD. The M4 muscarinic acetylcholine receptor (mAChR) was downregulated at the gene and protein levels in the putamen, but not in the caudate, of AUD samples. We found concordant downregulation of the M4 mAChR, specifically on dopamine D1 receptor-expressing medium spiny neurons in the rat dorsolateral striatum. Systemic administration of the selective M4 mAChR positive allosteric modulator, VU0467154, reduced home cage and operant alcohol self-administration, motivation to obtain alcohol, and cue-induced reinstatement of alcohol seeking in rats. Local microinjections of VU0467154 in the rat dorsolateral striatum reduced alcohol self-administration and cue-induced reinstatement of alcohol seeking.

CONCLUSIONS

Collectively, these results identify the M4 mAChR as a potential therapeutic target for the treatment of AUD and the D1 receptor-positive medium spiny neurons in the dorsolateral striatum as a key site mediating the actions of M4 mAChR in relation to alcohol consumption and seeking.

Anterior Insular Cortex is Critical for the Propensity to Relapse Following Punishment-Imposed Abstinence of Alcohol Seeking

Humans with alcohol use disorder typically abstain because of the negative consequences associated with excessive drinking, and exposure to contexts previously associated with alcohol use can trigger relapse. We used a rat model that captures a characteristic of this human condition: namely voluntary abstinence from alcohol use because of contingent punishment. There is substantial variability in the propensity to relapse following extended periods of abstinence, and this is a critical feature preventing the successful treatment of alcohol use disorder. Here we examined relapse following acute or prolonged abstinence. In male alcohol preferring P rats, we found an increased propensity to relapse in Context B, the punishment context after prolonged abstinence. Next, we found that neither alcohol intake history nor the motivational strength of alcohol predicted the propensity to relapse. We next examined the putative circuitry of context-induced relapse to alcohol seeking following prolonged abstinence using Fos as a marker of neuronal activation. The anterior insular cortex (AI) was the only brain region examined where Fos expression correlated with alcohol seeking behavior in Context B after prolonged abstinence. Finally, we used local infusion of GABAA and GABAB receptor agonists (muscimol + baclofen) to show a causal role of the AI in context-induced relapse in Context B, the punishment context after prolonged abstinence. Our results show that there is substantial individual variability in the propensity to relapse in the punishment-associated context after prolonged abstinence, and this is mediated by activity in the AI.SIGNIFICANCE STATEMENT A key feature of alcohol use disorder is that sufferers show an enduring propensity to relapse throughout their lifetime. Relapse typically occurs despite the knowledge of adverse consequences including health complications or relationship breakdowns. Here we use a recently developed rodent model that recapitulates this behavior. After an extended period of abstinence, relapse propensity is markedly increased in the "adverse consequence" environment, akin to humans with alcohol use disorder relapsing in the face of adversity. From a circuitry perspective, we demonstrate a causal role of the anterior insular cortex in relapse to alcohol seeking after extended abstinence following punishment imposed voluntary cessation of alcohol use.

WFSBP * and IAWMH ** Guidelines for the treatment of alcohol use disorders in pregnant women

OBJECTIVES

These practice guidelines for the treatment of alcohol use disorders during pregnancy were developed by members of the International Task Force of the World Federation of Societies of Biological Psychiatry and the International Association for Women's Mental Health.

METHODS

We performed a systematic review of all available publications and extracted data from national and international guidelines. The Task Force evaluated the data with respect to the strength of evidence for the efficacy and safety of each medication.

RESULTS AND DISCUSSION

There is no safe level of alcohol use during pregnancy. Abstinence is recommended. Ideally, women should stop alcohol use when pregnancy is planned and, in any case, as soon as pregnancy is known. Detecting patterns of alcohol maternal drinking should be systematically conducted at first antenatal visit and throughout pregnancy. Brief interventions are recommended in the case of low or moderate risk of alcohol use. Low doses of benzodiazepines, for the shortest duration, may be used to prevent alcohol withdrawal symptoms when high and chronic alcohol intake is stopped and hospitalisation is recommended. Due to the low level of evidence and/or to low benefit/risk ratio, pharmacological treatment for maintenance of abstinence should not be used during pregnancy. At birth, foetal alcohol spectrum disorders must be searched for, and alcohol metabolites should be measured in meconium of neonates in any doubt of foetal alcohol exposure.

A Retrospective Cohort Study of Birth Outcomes in Neonates Exposed to Naltrexone in Utero: A Comparison with Methadone-, Buprenorphine- and Non-opioid-Exposed Neonates

BACKGROUND

Naltrexone may provide a suitable alternative to methadone and buprenorphine in the treatment of pregnant opioid-dependent women; however, little is known about its effects on neonatal morbidity and mortality.

OBJECTIVE

The aim was to evaluate the health of neonates exposed to naltrexone in utero, and compare it with outcomes in neonates exposed to methadone or buprenorphine and a non-exposed control group.

METHODS

Sequential cohorts of Western Australian (WA) opioid-dependent women treated with implant naltrexone, oral methadone or sublingual buprenorphine were identified via records from a drug and alcohol clinic (Subiaco, WA) for naltrexone and state prescribing records for methadone and buprenorphine. A control cohort of non-opioid-dependent women was obtained from the WA electoral roll. Identifying information and treatment records for these women were linked against the Midwife Notification System records to identify exposed offspring born between 2001 and 2011. Birth characteristics, congenital anomalies and perinatal mortality for all neonates were extracted from state records.

RESULTS

The birth characteristics of naltrexone-exposed neonates (n = 68) were superior to methadone-exposed neonates (n = 199) in terms of birth size (birth weight, head circumference and length), hospital length of stay (5.5 vs. 11.3 days), and rates of neonatal abstinence syndrome (NAS) (7.5 vs. 51.5%). Naltrexone-exposed neonates were generally not significantly different to buprenorphine-exposed neonates (n = 124), with the exception of significantly lower rates of NAS (7.5 vs. 41.8%) and shorter hospital length of stay (5.5 vs. 8.0 days) in naltrexone-exposed neonates. Compared with the control group of neonates (n = 569), naltrexone-exposed neonates were not significantly different in terms of overall rates of congenital anomalies, stillbirths and neonatal mortality; however, they were significantly smaller (3137.1 vs. 3378.0 g), spent more time in hospital following birth (5.5 vs. 4.3 days) and had higher rates of NAS (7.5 vs. 0.2%). Exposure of neonates to prenatal methadone was associated with a high incidence of neonatal mortality (2.0 vs. 0.2 per 100 live births) and congenital anomalies (10.6 vs. 4.4 per 100 births) compared with the control group. Rates of neonatal mortality and congenital abnormalities in buprenorphine-exposed neonates were not significantly different to the control group.

CONCLUSIONS

The use of implant naltrexone during pregnancy was not associated with higher rates of negative birth outcomes compared with methadone- and buprenorphine-exposed neonates. Significantly, naltrexone and buprenorphine were not associated with the high rates of neonatal mortality or congenital anomalies seen in methadone-exposed neonates.

Methadone, Buprenorphine, and Naltrexone for the Treatment of Opioid Use Disorder in Pregnant Women

Pregnant women with opioid use disorder can be treated with methadone, buprenorphine, or naltrexone to reduce opioid use and improve retention to treatment. In this review, we compare the pregnancy outcomes of methadone, buprenorphine, and naltrexone in clinical trials and discuss the potential behavioral and developmental effects of these agents seen in offspring in animal studies. Important clinical considerations in the management of opioid use disorder in pregnant women and their infants are also discussed. Outside of pregnancy, buprenorphine is used in combination with naloxone to reduce opioid abuse and diversion. During pregnancy, however, the use of buprenorphine as a single agent is preferred to prevent prenatal naloxone exposure. Both methadone and buprenorphine are widely used to treat opioid use disorder; however, compared with methadone, buprenorphine is associated with shorter treatment duration, less medication needed to treat neonatal abstinence syndrome (NAS) symptoms, and shorter hospitalizations for neonates. Despite being the standard of care, medication-assisted treatment with methadone or buprenorphine is still underused, making it apparent that more options are necessary. Naltrexone is not a first-line treatment primarily because both detoxification and an opioid-free period are required. More research is needed to determine naltrexone safety and benefits in pregnant women. Animal studies suggest that changes in pain sensitivity, developmental processes, and behavioral responses may occur in children born to mothers receiving methadone, buprenorphine, or naltrexone and is an area that warrants future studies.

Caring for Pregnant Women with Opioid Use Disorder in the USA: Expanding and Improving Treatment

PURPOSE OF THE REVIEW

Opioid use disorder in the USA is rising at an alarming rate, particularly among women of childbearing age. Pregnant women with opioid use disorder face numerous barriers to care, including limited access to treatment, stigma, and fear of legal consequences. This review of opioid use disorder in pregnancy is designed to assist health care providers caring for pregnant and postpartum women with the goal of expanding evidence-based treatment practices for this vulnerable population.

RECENT FINDINGS

We review current literature on opioid use disorder among US women, existing legislation surrounding substance use in pregnancy, and available treatment options for pregnant women with opioid use disorder. Opioid agonist treatment (OAT) remains the standard of care for treating opioid use disorder in pregnancy. Medically assisted opioid withdrawal ("detoxification") is not recommended in pregnancy and is associated with high maternal relapse rates. Extended release naltrexone may confer benefit for carefully selected patients. Histories of trauma and mental health disorders are prevalent in this population; and best practice recommendations incorporate gender-specific, trauma-informed, mental health services. Breastfeeding with OAT is safe and beneficial for the mother-infant dyad.

SUMMARY

Further research investigating options of OAT and the efficacy of opioid antagonists in pregnancy is needed. The US health care system can adapt to provide quality care for these mother-infant dyads by expanding comprehensive treatment services and improving access to care.

Role of Dopamine 2 Receptor in Impaired Drug-Cue Extinction in Adolescent Rats

Adolescent drug users display resistance to treatment such as cue exposure therapy (CET), as well as increased liability to relapse. The basis of CET is extinction learning, which involves dopamine signaling in the medial prefrontal cortex (mPFC). This system undergoes dramatic alterations during adolescence. Therefore, we investigated extinction of a cocaine-associated cue in adolescent and adult rats. While cocaine self-administration and lever-alone extinction were not different between the two ages, we observed that cue extinction reduced cue-induced reinstatement in adult but not adolescent rats. Infusion of the selective dopamine 2 receptor (D2R)-like agonist quinpirole into the infralimbic cortex (IL) of the mPFC prior to cue extinction significantly reduced cue-induced reinstatement in adolescents. This effect was replicated by acute systemic treatment with the atypical antipsychotic aripiprazole (Abilify), a partial D2R-like agonist. These data suggest that adolescents may be more susceptible to relapse due to a deficit in cue extinction learning, and highlight the significance of D2R signaling in the IL for cue extinction during adolescence. These findings inspire new tactics for improving adolescent CET, with aripiprazole representing an exciting potential pharmacological adjunct for behavioral therapy.

The metabotropic glutamate 5 receptor is necessary for extinction of cocaine-associated cues

BACKGROUND AND PURPOSE

There is currently no medication approved specifically to treat cocaine addiction. Behavioural interventions such as cue exposure therapy (CET) rely heavily on new learning. Antagonism of the metabotropic glutamate 5 (mGlu5 ) receptor has emerged as a potential treatment, by reducing the reinforcing properties of cocaine. However, mGlu5 receptor activity is necessary for learning; therefore, such agents could interfere with behavioural treatments. We used a novel rodent model of CET to test the effects of mGlu5 negative and positive allosteric modulators (NAM and PAM) on behavioural therapy.

EXPERIMENTAL APPROACH

Rats were trained to press a lever for cocaine in the presence of a discrete cue [conditioned stimulus (CS)] and then extinguished in the absence of the CS. Following lever extinction, half the rats received CS extinction in the same chambers but with the levers withdrawn; the remaining rats received no CS extinction. Before this session, rats received a systemic administration of either vehicle or a mGlu5 NAM (MTEP, experiment 1) or PAM (CDPPB, experiment 2). Cue-induced reinstatement was tested in a drug-free session the following day.

KEY RESULTS

At reinstatement, rats that had received CS extinction showed reduced responding. This effect was attenuated by MTEP treatment before CS extinction. In contrast, administration of CDPPB (PAM) led to decreased reinstatement the following day, regardless of extinction condition.

CONCLUSION AND IMPLICATIONS

These results suggest that mGlu5 receptor activity is both necessary and sufficient for efficient extinction of a cocaine-associated CS. Therefore, mGlu5 PAMs could enhance the efficacy of CET.

Extinction of a cocaine-taking context that protects against drug-primed reinstatement is dependent on the metabotropic glutamate 5 receptor

We investigated the effects of extinguishing action-reward versus context-reward associations on drug-primed reinstatement, and the potential role of the metabotropic glutamate 5 receptor (mGlu5) in these different types of extinction in rats that self-administer cocaine. We observed that daily context extinction (non-reinforced exposures to the cocaine-taking context with retracted levers) was just as effective as daily lever extinction in reducing cocaine-primed reinstatement compared with passive abstinence. Additionally, systemic injections of the mGlu5 negative allosteric modulator MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine) following each extinction session significantly impaired the ability of context extinction to reduce cocaine-primed reinstatement, without affecting reinstatement after lever extinction or passive abstinence.

Developmental consequences of fetal exposure to drugs: what we know and what we still must learn

Most drugs of abuse easily cross the placenta and can affect fetal brain development. In utero exposures to drugs thus can have long-lasting implications for brain structure and function. These effects on the developing nervous system, before homeostatic regulatory mechanisms are properly calibrated, often differ from their effects on mature systems. In this review, we describe current knowledge on how alcohol, nicotine, cocaine, amphetamine, Ecstasy, and opiates (among other drugs) produce alterations in neurodevelopmental trajectory. We focus both on animal models and available clinical and imaging data from cross-sectional and longitudinal human studies. Early studies of fetal exposures focused on classic teratological methods that are insufficient for revealing more subtle effects that are nevertheless very behaviorally relevant. Modern mechanistic approaches have informed us greatly as to how to potentially ameliorate the induced deficits in brain formation and function, but conclude that better delineation of sensitive periods, dose-response relationships, and long-term longitudinal studies assessing future risk of offspring to exhibit learning disabilities, mental health disorders, and limited neural adaptations are crucial to limit the societal impact of these exposures.

Behavioral effects of perinatal opioid exposure

Opioids are among the world's oldest known drugs used mostly for pain relief, but recreational use is also widespread. A particularly important problem is opioid exposure in females, as their offspring can also be affected. Adverse intrauterine and postnatal environments can affect offspring development and may lead to various disabilities later in life. It is clear that repetitive painful experiences, such as randomly occurring invasive procedures during neonatal intensive care, can permanently alter neuronal and synaptic organization and therefore later behavior. At the same time, analgesic drugs can also be harmful, inducing neuronal apoptosis or withdrawal symptoms in the neonate and behavioral alterations in adulthood. Hence, risk-benefit ratios should be taken into consideration when pain relief is required during pregnancy or in neonates. Recreational use of opioids can also alter many aspects of life. Intrauterine opioid exposure has many toxic effects, inducing poor pregnancy outcomes due to underdevelopment, but it is believed that later negative consequences are more related to environmental factors such as a chaotic lifestyle and inadequate prenatal care. One of the crucial components is maternal care, which changes profoundly in addicted mothers. In substance-dependent mothers, pre- and postnatal care has special importance, and controlled treatment with a synthetic opioid (e.g., methadone) could be beneficial. We aimed to summarize and compare human and rodent data, as it is important to close the gap between scientific knowledge and societal policies. Special emphasis is given to gender differences in the sensitivity of offspring to perinatal opioid exposure.

Endogenous opiates and behavior: 2012

This paper is the thirty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2012 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).