Post Traumatic Stress Disorder and Substance Use Disorder as Two Pathologies Affecting Memory Reactivation: Implications for New Therapeutic Approaches

Estrogen receptor beta signaling enhances extinction memory recall for heroin-conditioned cues in a sex- and region-specific manner

Return to use, or relapse, is a major challenge in the treatment of opioid use disorder (OUD). Relapse can be precipitated by several factors, including exposure to drug-conditioned cues. Identifying successful treatments to mitigate cue-induced relapse has been challenging, perhaps due to extinction memory recall (EMR) deficits. Previously, inhibition of estradiol (E2) signaling in the basolateral amygdala (BLA) impaired heroin-cue EMR. This effect was recapitulated by antagonism of BLA estrogen receptors (ER) in a sex-specific manner such that blocking ERα in males, but ERβ in females, impaired EMR. However, it is unclear whether increased E2 signaling, in the BLA or systemically, enhances heroin-cue EMR. We hypothesized that ERβ agonism would enhance heroin-cue EMR in a sex- and region-specific manner. To determine the capacity of E2 signaling to improve EMR, we pharmacologically manipulated ERβ across several translationally designed experiments. First, male and female rats acquired heroin or sucrose self-administration. Next, during a cued extinction session, we administered diarylpropionitrile (DPN, an ERβ agonist) and tested anxiety-like behavior on an open field. Subsequently, we assessed EMR in a cue-induced reinstatement test and, finally, measured ERβ expression in several brain regions. Across all experiments, females took more heroin and sucrose than males and had greater responses during heroin-cued extinction. Administration of DPN in the BLA enhanced EMR in females only, driven by ERβ's impacts on memory consolidation. Interestingly, however, systemic DPN administration improved EMR for heroin cues in both sexes across several different tests, but did not impact sucrose-cue EMR. Immunohistochemical analysis of ERβ expression across several different brain regions showed that females only had greater expression of ERβ in the basal nucleus of the BLA. Here, in several preclinical experiments, we demonstrated that ERβ agonism enhances heroin-cue EMR and has potential utility in combatting cue-induced relapse.

The acceptability and feasibility of a virtual mantram program for patients with posttraumatic stress disorder and substance use disorders: mixed method results

BACKGROUND

There is a need for expanded options for therapeutic interventions for patients with posttraumatic stress disorder (PTSD) and substance use disorder (SUD). The study aimed to examine evidence for the feasibility, safety, and acceptability of a virtual Mantram Repetition Program for adults with PTSD and SUD.

METHODS

This project utilized mixed-method design (explanatory sequential design) to collect quantitative and qualitative data to evaluate the program in terms of its feasibility and acceptability. The program took place over Webex, an encrypted virtual platform. The group ran over 8 weeks, was 90 min in length, and facilitated by two individuals per cohort. Each group had 4-5 participants given each group cycle. The study used the Mantram Repetition Program which is a brief mindfulness based non-tramua focused group intervention.

RESULTS

Out of 43 participants enrolled, 5 people (11.6%) did not commence the program and 8 (18.6%) participants dropped out after commencing the program, resulting in 35 completers (81.4% retention rate). Treatment completion and retention were above 70%. Qualitative data explained several aspects of the program's acceptability including delivery methods, informative material provided and gaining a practical mindful tool to manage symptoms.

CONCLUSIONS

This study showed quantitative and qualitative evidence of the Mantram Repetition Program's feasibility, acceptability and safety to be used with individuals with PTSD-SUD. Although further evaluation of virtual Mantram Program to control group in longitudinal trials is needed to identify how it compares with other interventions in the field.

CLINICAL TRIAL REGISTRATION NUMBER

NCT05058963, (28/09/2021).

Inhibition of Estradiol Signaling in the Basolateral Amygdala Impairs Extinction Memory Recall for Heroin-Conditioned Cues in a Sex-Specific Manner

INTRODUCTION

Relapse is a major treatment barrier for opioid use disorder. Environmental cues become associated with the rewarding effects of opioids and can precipitate relapse, even after numerous unreinforced cue presentations, due to deficits in extinction memory recall (EMR). Estradiol (E2) modulates EMR of fear-related cues, but it is unknown whether E2 impacts EMR of reward cues and what brain region(s) are responsible for E2s effects. Here, we hypothesize that inhibition of E2 signaling in the basolateral amygdala (BLA) will impair EMR of a heroin-associated cue in both male and female rats.

METHODS

We pharmacologically manipulated E2 signaling to characterize the role of E2 in the BLA on heroin-cue EMR. Following heroin self-administration, during which a light/tone cue was co-presented with each heroin infusion, rats underwent cued extinction to extinguish the conditioned association between the light/tone and heroin. During extinction, E2 signaling in the BLA was blocked by an aromatase inhibitor or specific estrogen receptor (ER) antagonists. The next day, subjects underwent a cued test to assess heroin-cue EMR.

RESULTS

In both experiments, females took more heroin than males (mg/kg) and had higher operant responding during cued extinction. Inhibition of E2 synthesis in the BLA impaired heroin-cue EMR in both sexes. Notably, E2s actions are mediated by different ER mechanisms, ERα in males but ERβ in females.

CONCLUSIONS

This study is the first to demonstrate a behavioral role for centrally-produced E2 in the BLA and that E2 also impacts EMR of reward-associated stimuli in both sexes.

Relations Between Posttraumatic Stress Disorder Symptoms and Positive Memory Characteristics Among Women Reporting Intimate Partner Violence: A Micro-Longitudinal Study

Evidence links posttraumatic stress disorder (PTSD) symptoms to positive autobiographical memory characteristics. To extend this research, we uniquely utilized micro-longitudinal data to examine (1) the trajectory of PTSD symptom count across 30 days; and (2) if more vividness and accessibility of retrieved positive memories at the daily level predicted decreases in the trajectory of PTSD symptom count across 30 days. The current study was a secondary data analysis of a larger study. The sample included 74 women who reported physical or sexual victimization in the past 30 days by their current male partner and reported the use of alcohol and/or drugs during that time (M_age = 39.68 years; 37.80% with diagnostic PTSD; 43.2% White; 37.8% Black or African American). They completed thrice daily measures of PTSD symptoms and positive memory characteristics (vividness and accessibility) across 30 days. Results of the random effects longitudinal multilevel model indicated that, on average, the relation between PTSD symptom count and positive memory vividness was positive and statistically significant (0.19, 95% Confidence Interval [CI] [0.2, 0.35]); and the relation between PTSD symptom count and positive memory accessibility was positive and statistically significant (0.31, 95% CI [0.15, 0.47]). The relationship between PTSD symptom count and positive memory vividness/accessibility (i.e., slopes) varied significantly across participants, with a wide range of positive and negative regression coefficients. Future research needs to investigate why and how positive memory vividness and accessibility may relate to trajectories of PTSD symptoms over time, with potential clinical implications for positive memory interventions addressing PTSD.

Associations between positive memory count and hazardous substance use in a trauma-exposed sample: Examining the moderating role of emotion dysregulation

OBJECTIVES

Research has demonstrated links between autobiographical memory retrieval and hazardous substance use. However, limited work has examined relations between positive autobiographical memories and hazardous substance use, as well as moderating factors influencing these relations. Thus, we examined the potential moderating roles of negative and positive emotion dysregulation in the relations between count of retrieved positive memories and hazardous substance use (alcohol and drug use separately).

METHODS

Participants were 333 trauma-exposed students (Mage  = 21.05; 85.9% women) who completed self-report measures assessing positive memory count, hazardous alcohol and drug use, negative emotion dysregulation, and positive emotion dysregulation.

RESULTS

Positive emotion dysregulation significantly moderated the association between positive memory count and hazardous alcohol use (b = 0.04, 95% confidence interval [CI] [0.01, 0.06], p = 0.019), as well as the association between positive memory count and hazardous drug use (b = 0.02, 95% CI [0.01, 0.03], p = 0.002). Individuals with more positive emotion dysregulation had stronger associations between increases in positive memory count and increased hazardous substance use.

CONCLUSION

Findings indicate that trauma-exposed individuals who retrieve more positive memories and experience difficulties regulating positive emotions report greater hazardous substance use. Positive emotion dysregulation may be an important target for memory-based interventions among trauma-exposed individuals who report hazardous substance use.

Peptide LCGA-17 Attenuates Behavioral and Neurochemical Deficits in Rodent Models of PTSD and Depression

We have previously described the LCGA-17 peptide as a novel anxiolytic and antidepressant candidate that acts through the α2δ VGCC (voltage-gated calcium channel) subunit with putative synergism with GABA-A receptors. The current study tested the potential efficacy of acute and chronic intranasal (i.n.) LCGA-17 (0.05 mg/kg and 0.5 mg/kg) in rats on predator odor-induced conditioned place aversion (POCPA), a model of post-traumatic stress disorder (PTSD), and chronic unpredictable stress (CUS) that produce a range of behavioral and physiological changes that parallel symptoms of depression in humans. CUS and LCGA-17 treatment effects were tested in the sucrose preference (SPT) social interaction (SI), female urine sniffing (FUST), novelty-suppressed feeding (NSFT), and forced swim (FST) tests. Analysis of the catecholamines content in brain structures after CUS was carried out using HPLC. The efficacy of i.n. LCGA-17 was also assessed using the Elevated plus-maze (EPM) and FST. Acute LCGA-17 administration showed anxiolytic and antidepressant effects in EPM and FST, similar to diazepam and ketamine, respectively. In the POCPA study, LCGA-17 significantly reduced place aversion, with efficacy greater than doxazosin. After CUS, chronic LCGA-17 administration reversed stress-induced alterations in numerous behavioral tests (SI, FUST, SPT, and FST), producing significant anxiolytic and antidepressant effects. Finally, LCGA-17 restored the norepinephrine levels in the hippocampus following stress. Together, these results support the further development of the LCGA-17 peptide as a rapid-acting anxiolytic and antidepressant.

The Relationship between Positive Memory Phenomenology and Alcohol Use among Trauma-Exposed Individuals

BACKGROUND

Evidence links positive memory characteristics and hazardous alcohol use (HAU). Relevant to the current study, evidence also indicates that trauma-exposed individuals, especially those with posttraumatic stress disorder (PTSD) symptoms, report difficulties retrieving/accessing positive memories and report HAU.

OBJECTIVE

Considering this literature, we uniquely examined if and which positive memory characteristics were associated with HAU, and the potential mediating role of PTSD symptom severity in the examined relations.

METHODS

A sample of 126 trauma-exposed community participants seeking mental health treatment (Mage=34.97 years) completed measures of HAU (Alcohol Use Disorders Identification Test), positive memory characteristics (Memory Experiences Questionnaire-Short Form [MEQ-SF]), and PTSD severity (PTSD Checklist for DSM-5). We conducted 8 hierarchical multiple regressions; Step 1 examined effects of gender and Step 2 added a single MEQ-SF dimension (specificity, valence, emotional intensity, sensory details, vividness, accessibility, coherence, sharing).

RESULTS

In Steps 1 (β=.27) and 2 (βs from .27-.28), gender was associated with HAU. In Step 2, positive memory characteristics of specificity (β=.17), sensory details (β=.17), sharing (β=.23), and valence (β=-.19) were associated with greater HAU. PTSD severity mediated relations between sensory details (β=.09, p=.048), emotional intensity (β=.12, p=.011), and sharing (β=.09, p=.036), and the extent of HAU.

CONCLUSIONS AND IMPLICATIONS

Results that specificity, greater sharing, more sensory details, and higher negative valence of positive memories were associated with greater HAU offer potential points of intervention.

Complex Interactions Between Sex and Stress on Heroin Seeking

Rationale: Stress plays a dual role in substance use disorders as a precursor to drug intake and a relapse precipitant. With heroin use at epidemic proportions in the United States, understanding interactions between stress disorders and opioid use disorder is vital and will aid in treatment of these frequently comorbid conditions. Objectives: Here, we combine assays of stress and contingent heroin self-administration (SA) to study behavioral adaptations in response to stress and heroin associated cues in male and female rats. Methods: Rats underwent acute restraint stress paired with an odor stimulus and heroin SA for subsequent analysis of stress and heroin cue reactivity. Lofexidine was administered during heroin SA and reinstatement testing to evaluate its therapeutic potential. Rats also underwent tests on the elevated plus maze, locomotor activity in a novel environment, and object recognition memory following stress and/or heroin. Results: A history of stress and heroin resulted in disrupted behavior on multiple levels. Stress rats avoided the stress conditioned stimulus and reinstated heroin seeking in response to it, with males reinstating to a greater extent than females. Lofexidine decreased heroin intake, reinstatement, and motor activity. Previous heroin exposure increased time spent in the closed arms of an elevated plus maze, activity in a round novel field, and resulted in object recognition memory deficits. Discussion: These studies report that a history of stress and heroin results in maladaptive coping strategies and suggests a need for future studies seeking to understand circuits recruited in this pathology and eventually help develop therapeutic approaches.

Critical considerations for the positive memory-posttraumatic stress disorder model

Posttraumatic stress disorder (PTSD) includes changes in processes such as encoding and retrieval for both traumatic and positive memories. However, most work has predominantly focused on traumatic memories. Thus, Contractor and colleagues proposed a Positive Memory-PTSD model, which highlighted potential benefits associated with and mechanisms underlying positive memory retrieval/processing among individuals reporting PTSD symptoms. To enhance research on and clinical impacts of this model, the current review provides critical considerations for the Positive Memory-PTSD model. Drawing from emerging research and clinical observations, we (i) clarify that the model addresses specific versus overgeneral positive memories; (ii) underscore the importance of considering the heterogeneity in, and transitionary nature of, affect processes following positive memory retrieval; and (iii) highlight the rationale for considering trauma type/count and co-occurring conditions, as potential moderators of relations between positive memory processing and PTSD. Hereby, we provide an updated Positive Memory-PTSD model and implications for positive memory interventions drawing from this model.

Predictors of substance use in a clinical sample of youth seeking treatment for Trauma-related mental health problems

Child maltreatment and traumatic events are well established risk factors for adolescent substance use problems, but little is known about the unique contributions of etiological factors on trauma-exposed youths' pre-treatment substance use in clinical settings. This study examined associations between substance use and risk and protective factors measured across multiple ecological levels among a unique sample of youth seeking treatment for trauma-related mental health problems in child advocacy centers. Participants were adolescents (N = 135; 85% female; 60% white, 31% black) aged 13-17 years (M = 15.4) with ≥ 1 experience of child maltreatment or other interpersonal violence, current substance use, and ≥5 PTSD symptoms. Youth and caregivers completed validated questionnaires and clinical interviews at a pre-treatment assessment in a randomized controlled trial of a treatment for co-occurring traumatic stress and substance use. Negative binomial regression models identified different patterns of risk and protective factors for alcohol and cannabis. Clinical implications of these results are discussed, including the potential targets for integrated psychotherapies that address co-occurring substance use and traumatic stress in youth.

Amphetamine Modulation of Long-Term Object Recognition Memory in Rats: Influence of Stress

Amphetamine is a potent psychostimulant that increases brain monoamine levels. Extensive evidence demonstrated that norepinephrine is crucially involved in the regulation of memory consolidation for stressful experiences. Here, we investigated amphetamine effects on the consolidation of long-term recognition memory in rats exposed to different intensities of forced swim stress immediately after training. Furthermore, we evaluated whether such effects are dependent on the activation of the peripheral adrenergic system. To this aim, male adult Sprague Dawley rats were subjected to an object recognition task and intraperitoneally administered soon after training with amphetamine (0.5 or 1 mg/kg), or its corresponding vehicle. Rats were thereafter exposed to a mild (1 min, 25 ± 1°C) or strong (5 min, 19 ± 1°C) forced swim stress procedure. Recognition memory retention was assessed 24-h after training. Our findings showed that amphetamine enhances the consolidation of memory in rats subjected to mild stress condition, while it impairs long-term memory performance in rats exposed to strong stress. These dichotomic effects is dependent on stress-induced activation of the peripheral adrenergic response.

The role of prelimbic and anterior cingulate cortices in fear memory reconsolidation and persistence depends on the memory age

Reconsolidation is a time-limited process under which reactivated memory content can be modified. Works focused on studying reconsolidation mainly restrict intervention to the moments immediately after reactivation and to recently acquired memories. However, the brain areas activated during memory retrieval depend on when it was acquired, and it is relatively unknown how different brain sites contribute to reconsolidation and persistence of reactivated recent and remote fear memories. Here, we sought to investigate the participation of prelimbic (PL) and anterior cingulate cortices (ACC) in recent (1 d old) and remote (21 d old) fear memory reconsolidation and persistence. Male Wistar rats were submitted to the contextual fear conditioning protocol. Tamoxifen (TMX), an estrogen receptor modulator known to inhibit protein kinase C activity was used to interfere with these processes. When infused into the PL cortex, but not into the ACC, TMX administration immediately or 6 h after recent fear memory reactivation impaired memory reconsolidation and persistence, respectively. TMX administered immediately after remote memory reactivation impaired memory reconsolidation when infused into the PL cortex and ACC. However, remote memory persistence was only affected when TMX was infused 6 h after memory reactivation into the ACC and no effect was observed when TMX was infused 6 h after memory reactivation into PL cortex. Together, the findings provide further evidence on the participation of PL cortex and ACC in reconsolidation of recent and remote fear memories and suggest that the persistence of a reactivated fear memory becomes independent on the PL cortex with memory age and dependent on the ACC.

Childhood Trauma, Cognitive Emotion Regulation and Motivation for Behavior Change Among Clients of Opioid Substitution Treatment With and Without Past Year Synthetic Cathinone Use During Therapy

Background

With a decrease in heroin's purity and availability in the European drug market, Hungarian opioid dependent patients started to substitute heroin with novel psychoactive substances (NPS) and especially with synthetic cathinones.

Goal

This study aims to assess whether clients of opioid substitution treatment (OST) with and without a history of synthetic cathinone use during therapy differ in (1) the rate and type of experienced childhood trauma, (2) the way they cope with negative life events, (3) their motivation to change substance use behavior, (4) the rate of treatment retention.

Methods

A total of 198 clients of an outpatient centers (Nyírõ Gyula National Institute of Psychiatry and Addictions, Budapest) OST were asked to provide information about their general substance use experiences, including the consumption of NPS during treatment, their childhood traumatic experiences (Childhood Trauma Questionnaire), cognitive emotion regulation strategies (Cognitive Emotion Regulation Questionnaire), their motivation to change substance use behavior (University of Rhode Island Change Assessment Scale) and current psychiatric symptoms (Brief Symptom Inventory). Baseline data was collected in the summer of 2015, while 4 years follow-up data on treatment retention was obtained in the summer of 2019.

Results

The majority of the clients were male (N = 141, 71.2%), receiving methadone as a substitute for opioids (N = 178, 89.9%), while mean age of the full sample was 39.7 (SD = 6.8). Based on a logistic regression model, the odds for past year synthetic cathinone use was higher among clients with more severe psychiatric symptoms (B = 0.8, OR = 2.2, p < 0.01) and among clients who were in treatment for a shorter period of time (B = 0.1, OR = 0.9, p < 0.05). Synthetic cathinone use during treatment was further associated with less adaptive strategies to cope with negative life events. Synthetic cathinone use was also a risk factor for reduced treatment retention (B = -0.8, OR = 0.4, p < 0.05) and was associated with lower odds of being member of a latent class with less severe psychopathological profile (B = -0.9, OR = 0.4, p < 0.05).

Conclusion

Synthetic cathinone use during treatment is associated with poorer treatment outcomes and might be characterized by more severe psychiatric symptoms and amotivation to change substance use among opioid dependent clients.

Emotional remodeling with oxytocin durably rescues trauma-induced behavioral and neuro-morphological changes in rats: a promising treatment for PTSD

Recent evidence indicates that reactivated memories are malleable and can integrate new information upon their reactivation. We injected rats with oxytocin to investigate whether the delivery of a drug which dampens anxiety and fear before the reactivation of trauma memory decreases the emotional load of the original representation and durably alleviates PTSD-like symptoms. Rats exposed to the single prolonged stress (SPS) model of PTSD were classified 15 and 17 days later as either resilient or vulnerable to trauma on the basis of their anxiety and arousal scores. Following 2 other weeks, they received an intracerebral infusion of oxytocin (0.1 µg/1 µL) or saline 40 min before their trauma memory was reactivated by exposure to SPS reminders. PTSD-like symptoms and reactivity to PTSD-related cues were examined 3-14 days after oxytocin treatment. Results showed that vulnerable rats treated with saline exhibited a robust PTSD syndrome including increased anxiety and decreased arousal, as well as intense fear reactions to SPS sensory and contextual cues. Exposure to a combination of those cues resulted in c-fos hypo-activation and dendritic arbor retraction in prefrontal cortex and amygdala neurons, relative to resilient rats. Remarkably, 83% of vulnerable rats subjected to oxytocin-based emotional remodeling exhibited a resilient phenotype, and SPS-induced morphological alterations in prelimbic cortex and basolateral amygdala were eliminated. Our findings emphasize the translational potential of the present oxytocin-based emotional remodeling protocol which, when administered even long after the trauma, produces deep re-processing of traumatic memories and durable attenuation of the PTSD symptomatology.

Reactivation of the Unconditioned Stimulus Inhibits the Return of Fear Independent of Cortisol

Reconsolidation is the post-retrieval stabilization of memories, a time-limited process during which reactivated (i.e., retrieved) memories can be updated with new information, become stronger or weaker, depending on the specific treatment. We have previously shown that the stress hormone cortisol has an enhancing effect on the reconsolidation of fear memories in men. This effect was specific, i.e., limited to the conditioned stimulus (CS) that was reactivated, and did not generalize to other previously reinforced, but not reactivated CS. Based on these results, we suggested that cortisol plays a critical role in the continuous strengthening of reactivated emotional memories, contributing to their persistence and robustness. In the current study, we aimed to achieve a more generalized reconsolidation enhancement using an alternative reactivation method, i.e., by a low-intensity unconditioned stimulus (UCS) presentation instead of the more common unreinforced CS presentation. In previous studies, UCS reactivation was shown to lead to a more generalized reconsolidation effect. Therefore, we hypothesized that the combination of cortisol treatment and UCS reactivation would lead to an enhanced fear memory reconsolidation, which would generalize from previously reinforced CS to stimuli that resemble it. We tested 75 men in a 3-day fear conditioning paradigm: fear acquisition training on day 1; UCS reactivation/no reactivation and pharmacological treatment (20 mg hydrocortisone/placebo) on day 2; extinction training, reinstatement and test (of original and modified stimuli) on day 3. In contrast to our hypothesis, UCS reactivation prevented the return of fear [observed in skin conductance responses (SCR)] regardless of the pharmacological manipulation: while reinstatement to the original CS was found in the no-reactivation group, both reactivation groups (cortisol and placebo) showed no reinstatement. As the only methodological difference between our previous study and the current one was the reactivation method, we focus on UCS reactivation as the main explanation for these unexpected findings. We suggest that the robust prediction error generated by the UCS reactivation method (as opposed to CS reactivation), combined with the lower UCS intensity, has by itself weakened the emotional value of the UCS, thus preventing the return of fear to the CS that was associated with it. We call for future research to support these findings and to examine the potential of this reactivation method, or variations thereof, as a tool for therapeutic use.

Effective Strategies for Working With Patients With Substance Use Disorders

Substance use is at epidemic proportions in the United States. Substance use disorders (SUDs) are difficult to treat and considered to be chronic with a high mortality rate. Nurses are in a prime position to help patients with SUDs in a variety of settings, but they often lack knowledge about the disorder and the skills to provide effective care. The identification and treatment of co-occurring disorders, such as trauma, are important when providing care for patients with SUDs. Empathy and perspective taking were once thought to be helpful when working with patients, but evolving thought is that compassion is more effective as it involves feeling for, and not with, patients and includes taking action to help another. Harm reduction strategies, such as accepting people where they are, as well as the use of motivational interviewing strategies are also effective when working with patients with SUDs. Involving patients with SUDs in their treatment plans through shared decision making is also effective in building a therapeutic relationship and improves outcomes. [Journal of Psychosocial Nursing and Mental Health Services, 57(9), 11-15.].

microRNA mir-598-3p mediates susceptibility to stress enhancement of remote fear memory

microRNAs (miRNAs) have emerged as potent regulators of learning, recent memory, and extinction. However, our understanding of miRNAs directly involved in regulating complex psychiatric conditions perpetuated by aberrant memory, such as in posttraumatic stress disorder (PTSD), remains limited. To begin to address the role of miRNAs in persistent memories, we performed small-RNA sequencing on basolateral amygdala (BLA) tissue and identified miRNAs altered by auditory fear conditioning (FC) one month after training. mir-598-3p, a highly conserved miRNA previously unstudied in the brain, was down-regulated in the BLA. Further decreasing BLA mir-598-3p levels did not increase strength of the remote fear memory. Given that stress is a critical component in PTSD, we next assessed the impact of stress and stress-enhanced fear learning (SEFL) on mir-598-3p levels, finding the miRNA is elevated in the BLA of male, but not female, mice susceptible to the effects of stress in SEFL. Accordingly, intra-BLA inhibition of mir-598-3p interfered with expression and extinction of the remote fear memory in male, but not female, mice. This effect could not be attributed to an anxiolytic effect of miRNA inhibition. Finally, bioinformatic analysis following quantitative proteomics on BLA tissue collected 30 d post-SEFL training identified putative mir-598-3p targets and related pathways mediating the differential susceptibility, with evidence for regulation of the actin cytoskeleton, the core mediator of structural plasticity. Taken together, the results suggest BLA mir-598-3p may be recruited by stress to mediate a critical switch from a salient remote fear memory to one that is enhanced and extinction-resistant.