Factors affecting increased risk for substance use disorders following traumatic brain injury: What we can learn from animal models

3'-Deoxyadenosin alleviates methamphetamine-induced aberrant synaptic plasticity and seeking behavior by inhibiting the NLRP3 inflammasome

JOURNAL/nrgr/04.03/01300535-202410000-00028/figure1/v/2024-02-06T055622Z/r/image-tiff Methamphetamine addiction is a brain disorder characterized by persistent drug-seeking behavior, which has been linked with aberrant synaptic plasticity. An increasing body of evidence suggests that aberrant synaptic plasticity is associated with the activation of the NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasome. 3'-Deoxyadenosin, an active component of the Chinese fungus Cordyceps militaris, has strong anti-inflammatory effects. However, whether 3'-deoxyadenosin attenuates methamphetamine-induced aberrant synaptic plasticity via an NLRP3-mediated inflammatory mechanism remains unclear. We first observed that 3'-deoxyadenosin attenuated conditioned place preference scores in methamphetamine-treated mice and decreased the expression of c-fos in hippocampal neurons. Furthermore, we found that 3'-deoxyadenosin reduced the aberrant potentiation of glutamatergic transmission and restored the methamphetamine-induced impairment of synaptic plasticity. We also found that 3'-deoxyadenosin decreased the expression of NLRP3 and neuronal injury. Importantly, a direct NLRP3 deficiency reduced methamphetamine-induced seeking behavior, attenuated the impaired synaptic plasticity, and prevented neuronal damage. Finally, NLRP3 activation reversed the effect of 3'-deoxyadenosin on behavior and synaptic plasticity, suggesting that the anti-neuroinflammatory mechanism of 3'-deoxyadenosin on aberrant synaptic plasticity reduces methamphetamine-induced seeking behavior. Taken together, 3'-deoxyadenosin alleviates methamphetamine-induced aberrant synaptic plasticity and seeking behavior by inhibiting the NLRP3 inflammasome.

Sex-Specific and Traumatic Brain Injury Effects on Dopamine Receptor Expression in the Hippocampus

Traumatic brain injury (TBI) is a major health concern. Each year, over 50 million individuals worldwide suffer from TBI, and this leads to a number of acute and chronic health issues. These include affective and cognitive impairment, as well as an increased risk of alcohol and drug use. The dopaminergic system, a key component of reward circuitry, has been linked to alcohol and other substance use disorders, and previous research indicates that TBI can induce plasticity within this system. Understanding how TBI modifies the dopaminergic system may offer insights into the heightened substance use and reward-seeking behavior following TBI. The hippocampus, a critical component of the reward circuit, is responsible for encoding and integrating the spatial and salient aspects of rewarding stimuli. This study explored TBI-related changes in neuronal D2 receptor expression within the hippocampus, examining the hypothesis that sex differences exist in both baseline hippocampal D2 receptor expression and its response to TBI. Utilizing D2-expressing tdTomato transgenic male and female mice, we implemented either a sham injury or the lateral fluid percussion injury (FPI) model of TBI and subsequently performed a region-specific quantification of D2 expression in the hippocampus. The results show that male mice exhibit higher baseline hippocampal D2 expression compared to female mice. Additionally, there was a significant interaction effect between sex and injury on the expression of D2 in the hippocampus, particularly in regions of the dentate gyrus. Furthermore, TBI led to significant reductions in hippocampal D2 expression in male mice, while female mice remained mostly unaffected. These results suggest that hippocampal D2 expression varies between male and female mice, with the female dopaminergic system demonstrating less susceptibility to TBI-induced plasticity.

Neuropathological Outcomes of Traumatic Brain Injury and Alcohol Use in Males and Females: Studies Using Pre-Clinical Rodent and Clinical Human Specimens

Traumatic brain injury (TBI) and alcohol misuse are inextricably linked and can increase the risk for development of neurodegenerative diseases, particularly in military veterans and contact sport athletes. Proteinopathy (defects in protein degradation) is considered an underlying factor in neurodegenerative diseases. Whether it contributes to TBI/alcohol-mediated neurodegeneration is unexplored, however. Our recent studies have identified ISGylation, a conjugated form of ISG15 (Interferon-Stimulated Gene 15) and inducer of proteinopathy, as a potential mechanistic link underlying TBI-mediated neurodegeneration and proteinopathy in veterans. In the current study, a rat model of combined TBI and alcohol use was utilized to investigate the same relationship. Here, we report sustained induction of Interferon β (IFNβ), changes in TAR DNA Binding 43 (TDP-43) ISGylation levels, TDP-43 proteinopathy (C-terminal fragmentation [CTF]), and neurodegeneration in the ventral horns of the lumbar spinal cords (LSCs) and/or motor cortices (MCs) of female rats post-TBI in a time-dependent manner. In males, these findings mostly remained non-significant, although moderate alcohol use appears to decrease neurodegeneration in males (but not females) post-TBI. We, however, do not claim that moderate alcohol consumption is beneficial for preventing TBI-mediated neurodegeneration. We have previously demonstrated that ISGylation is increased in the LSCs of veterans with TBI/ALS (amyotrophic lateral sclerosis). Here, we show increased ISGylation of TDP-43 in the LSCs of TBI/ALS-afflicted female veterans compared with male veterans. Knowing that ISGylation induces proteinopathy, we suggest targeting ISGylation may prevent proteinopathy-mediated neurodegeneration post-TBI, particularly in women; however, causal studies are required to confirm this claim.

Influence of Mild Traumatic Brain Injury History and Mental Health Status on Alcohol and Cannabis Use in University Athletes

OBJECTIVE

This study examined the relationship between mild traumatic brain injury (mTBI) history, mental health, and sex with single and polysubstance use in university athletes.

DESIGN

Observational study.

SETTING

University in Ontario, Canada.

PARTICIPANTS

Participants were identified from a dataset of 416 university athletes ages 18 to 21. Participants were classified based on their substance use habits and, 153 met criteria for the nonsubstance group, 195 for the alcohol use (AU) only group, and 64 polysubstance use group [ie, a combined substance use (AU+) group].

INDEPENDENT VARIABLES

Athletes received baseline assessments and completed self-reported questions regarding alcohol, cannabis, or other recreational substance use, the Patient Health Questionnaire-9, self-reported mTBI history, and self-reported anxiety, and/or panic disorder endorsement information.

MAIN OUTCOME MEASURES

Comparison of mTBI history and mental health status between individuals in the alcohol only or polysubstance use group.

RESULTS

Mild traumatic brain injury history was a significant predictor of AU ( P < 0.001) and AU+ ( P < 0.001). Anxiety endorsement was also a significant predictor of polysubstance use ( P < 0.001) and there was a small but nonsignificant association of polysubstance use in men ( P = 0.057).

CONCLUSIONS

University athletes who experience mTBI are more likely to engage in single or polysubstance use and athletes who experience anxiety are more likely to engage in polysubstance use. Consideration of mTBI history and mental health may inform clinical concussion management for identifying potential high-risk behavior such as polysubstance use in university athletes and tailoring intervention strategies (eg, incorporating education about substance use).

Chronicity of repeated blast traumatic brain injury associated increase in oxycodone seeking in rats

Numerous epidemiological studies have found co-morbidity between non-severe traumatic brain injury (TBI) and substance misuse in both civilian and military populations. Preclinical studies have also identified this relationship for some misused substances. We have previously demonstrated that repeated blast traumatic brain injury (rbTBI) increased oxycodone seeking without increasing oxycodone self-administration, suggesting that the neurological sequelae of traumatic brain injury can elevate opioid misuse liability. Here, we determined the chronicity of this effect by testing different durations of time between injury and oxycodone self-administration and durations of abstinence. We found that the subchronic (four weeks), but not the acute (three days) or chronic (four months) duration between injury and oxycodone self-administration was associated with increased drug seeking and re-acquisition of self-administration following a 10-day abstinence. Examination of other abstinence durations (two days, four weeks, or four months) revealed no effect of rbTBI on drug seeking at any of the abstinence durations tested. Together, these data indicate that there is a window of vulnerability after TBI when oxycodone self-administration is associated with elevated drug seeking and relapse-related behaviors.

Intimate partner violence, substance use, and health comorbidities among women: A narrative review

Exposure to intimate partner violence (IPV), including physical, sexual, and psychological violence, aggression, and/or stalking, impacts overall health and can have lasting mental and physical health consequences. Substance misuse is common among individuals exposed to IPV, and IPV-exposed women (IPV-EW) are at-risk for transitioning from substance misuse to substance use disorder (SUD) and demonstrate greater SUD symptom severity; this too can have lasting mental and physical health consequences. Moreover, brain injury is highly prevalent in IPV-EW and is also associated with risk of substance misuse and SUD. Substance misuse, mental health diagnoses, and brain injury, which are highly comorbid, can increase risk of revictimization. Determining the interaction between these factors on the health outcomes and quality of life of IPV-EW remains a critical need. This narrative review uses a multidisciplinary perspective to foster further discussion and research in this area by examining how substance use patterns can cloud identification of and treatment for brain injury and IPV. We draw on past research and the knowledge of our multidisciplinary team of researchers to provide recommendations to facilitate access to resources and treatment strategies and highlight intervention strategies capable of addressing the varied and complex needs of IPV-EW.

Does Traumatic Brain Injury Cause Risky Substance Use or Substance Use Disorder?

There is a high co-occurrence of risky substance use among adults with traumatic brain injury (TBI), although it is unknown if the neurologic sequelae of TBI can promote this behavior. We propose that to conclude that TBI can cause risky substance use, it must be determined that TBI precedes risky substance use, that confounders with the potential to increase the likelihood of both TBI and risky substance use must be ruled out, and that there must be a plausible mechanism of action. In this review, we address these factors by providing an overview of key clinical and preclinical studies and list plausible mechanisms by which TBI could increase risky substance use. Human and animal studies have identified an association between TBI and risky substance use, although the strength of this association varies. Factors that may limit detection of this relationship include differential variability due to substance, sex, age of injury, and confounders that may influence the likelihood of both TBI and risky substance use. We propose possible mechanisms by which TBI could increase substance use that include damage-associated neuroplasticity, chronic changes in neuroimmune signaling, and TBI-associated alterations in brain networks.

Endogenous Opioid Dynorphin Is a Potential Link between Traumatic Brain Injury, Chronic Pain, and Substance Use Disorder

Traumatic brain injury (TBI) is a serious public health problem associated with numerous physical and neuropsychiatric comorbidities. Chronic pain is prevalent and interferes with post-injury functioning and quality of life, whereas substance use disorder (SUD) is the third most common neuropsychiatric diagnosis after TBI. Neither of these conditions has a clear mechanistic explanation based on the known pathophysiology of TBI. Dynorphin is an endogenous opioid neuropeptide that is significantly dysregulated after TBI. Both dynorphin and its primary receptor, the ĸ-opioid receptor (KOR), are implicated in the neuropathology of chronic pain and SUD. Here, we review the known roles of dynorphin and KORs in chronic pain and SUDs. We synthesize this information with our current understanding of TBI and highlight potential mechanistic parallels between and across conditions that suggest a role for dynorphin in long-term sequelae after TBI. In pain studies, dynorphin/KOR activation has either antinociceptive or pro-nociceptive effects, and there are similarities between the signaling pathways influenced by dynorphin and those underlying development of chronic pain. Moreover, the dynorphin/KOR system is considered a key regulator of the negative affective state that characterizes drug withdrawal and protracted abstinence in SUD, and molecular and neurochemical changes observed during the development of SUD are mirrored by the pathophysiology of TBI. We conclude by proposing hypotheses and directions for future research aimed at elucidating the potential role of dynorphin/KOR in chronic pain and/or SUD after TBI.

Risk Factors Associated With the Prescription of Opioids Among Service Members Following a First Mild Traumatic Brain Injury

OBJECTIVE

To evaluate factors impacting opioid receipt among active-duty service members (SMs) following a first mild traumatic brain injury (mTBI).

SETTING

Active-duty SMs receiving care within the Military Health System.

PARTICIPANTS

In total, 14 757 SMs who have sustained an initial mTBI, as documented within electronic health records (EHRs), between 2016 and 2017.

DESIGN

A retrospective analysis of EHR metadata.

MAIN MEASURES

Multivariable logistic regression assessed factors impacting opioid receipt and initiation. Factors include demographics, military characteristics, and preexisting clinical conditions, including prior opioid prescription.

RESULTS

Of the sample population, 33.4% (n = 4927) were prescribed opioids after their initial mTBI, of which, 60.6% (n = 2985) received opioids for the first time following injury. Significant risk factors associated with the increased probability of opioid receipt included age, gender, and preexisting behavioral health and musculoskeletal conditions. Military characteristics also exhibited changes in the probability of opioid receipt, both among initiation and new prescription. No changes were observed among race, nor among those with preexisting headaches or migraines.

CONCLUSION

Despite concerns about the negative impact on recovery, the prescribing of opioids is common in this population of active-duty SMs first diagnosed with an mTBI. As several demographic and preexisting health conditions are factors in the receipt of opioids post-mTBI, the entire medical history of these patients should be considered prior to prescription. Understanding these factors may further inform policy for opioid use in the Military Health System.

Scoping Review of Opioid Use After Traumatic Brain Injury

OBJECTIVE

To summarize the current literature to identify what research has been conducted, examine the approaches used, and determine what is presently known about prescription and nonprescription opioid receipts and use among individuals with traumatic brain injury (TBI).

DATA SOURCES

The search strategy included the following: opioid; opiate; analgesics, opioid; opiate alkaloids; or opioid-related disorders; AND brain injury; brain injuries; brain injuries, traumatic; head injury; head injuries; head injuries, closed; head injuries, penetrating; brain concussion; diffuse axonal injury; diffuse axonal injuries; brain trauma/s; head trauma/s; concussion; craniocerebral trauma/s; or TBI. Filters included English and Adults (19+ years). Study Selection: Inclusion: English language, adults with stable TBI, and prescription opioid receipt or use after TBI. Exclusion: Animal models, populations with other acquired brain injury, acute TBI management, and non-peer-reviewed articles, theses, or conference abstracts. Multiple reviewers screened abstracts and full-text articles for eligibility. In total, 771 abstracts were screened, 183 full texts were reviewed, and 21 met eligibility criteria. Data Extraction: Relevant content was independently extracted by multiple observers, including authors, design, sample identification and data source/s, TBI severity, TBI assessment, opioid assessment, study population (demographics, N), military affiliation, comparison groups, date of data collection, and summary of findings.

RESULTS

Studies were published between 1987 and 2019; most data were collected prior to 2015. The majority utilized administrative and electronic medical record data from the Department of Veterans Affairs and retrospective cohort designs, and most focused on prescription opioids. There were no studies evaluating interventions to reduce use of opioids in TBI populations. Preliminary findings suggest that prescription opioid receipt is strongly related to psychological symptoms, including comorbid depression, anxiety, and posttraumatic stress disorder.

CONCLUSIONS

Despite increased awareness of opioid receipt and use following TBI, there is limited investigation on the examination of this issue. Future studies should include more varied patient populations as well as evaluate interventions to reduce opioid use following TBI.

TBI as a Risk Factor for Substance Use Behaviors: A Meta-analysis

OBJECTIVE

To quantify the relationship between substance use behaviors before and after traumatic brain injury (TBI), to identify populations that may benefit more from targeted interventions to reduce the effect of substance use on TBI recovery, and to establish areas for further study.

DATA SOURCES

Studies were identified via literature searches using MEDLINE, PsychInfo, PsychArticles, PubMed, and GoogleScholar (published before January 2019), as well as reference section reviews and forward searches. Searches were conducted using search terms for TBI and substance use behaviors.

STUDY SELECTION

Studies were included if they (1) contained both a measure of TBI and a measure of substance use behaviors; (2) reported an effect size representing the relationship between substance use behaviors before and after TBI, compared TBI vs non-TBI groups on substance use behaviors controlling for pre-TBI substance use, or compared groups with differing TBI severity on subsequent substance use behaviors controlling for pre-TBI substance use; (3) were written in English; and (4) were human subjects research. Studies examining effects of substance use intervention for people sustaining TBI were excluded from this study.

DATA EXTRACTION

Study variables included substance use behaviors, TBI severity, time since TBI, military status, age, race, and sex.

DATA SYNTHESIS

Substance use behaviors had a small but statistically significant decrease after moderate-severe TBI. After moderate-severe TBI, there was a statistically significant decline in both substance use (d=-0.29, P<.01) and negative substance use consequences (d=-0.67, P=.01). There was no significant change in substance use behaviors after mild TBI.

CONCLUSIONS

Substance use behaviors had a small decrease after moderate to severe TBI and no significant change after mild TBI. Study findings suggest the need for accurate assessment to identify those at greatest risk for problematic substance use behaviors after TBI.

Traumatic brain injury and the misuse of alcohol, opioids, and cannabis

Traumatic brain injury (TBI), most often classified as concussion, is caused by biomechanical forces to the brain resulting in short- or long-term impairment in brain function. TBI resulting from military combat, sports, violence, falls, and vehicular accidents is a major cause of long-term physical, cognitive, and psychiatric dysfunction. Psychiatric disorders associated with TBI include depression, anxiety, and substance use disorder, all having significant implications for post-TBI recovery and rehabilitation. This chapter reviews the current preclinical and clinical literature describing the bidirectional relationship between TBI and misuse of three commonly abused drugs: alcohol, opioids, and cannabis. We highlight the influence of each of these drugs on the incidence of TBI, as well as trends in their use after TBI. Furthermore, we discuss factors that may underlie post-injury substance use. Understanding the complex relationship between TBI and substance misuse will enhance the clinical treatment of individuals suffering from these two highly comorbid conditions.

Alcohol use disorders and the brain

A diagnosis of alcohol use disorder is associated with a higher risk of dementia, but a dose-response relationship between alcohol intake consumption and cognitive impairment remains unclear. Alcohol is associated with a range of effects on the central nervous system at different doses and acts on a number of receptors. Acute disorders include Wernicke's encephalopathy (WE), traumatic brain injury, blackouts, seizures, stroke and hepatic encephalopathy. The most common manifestations of chronic alcohol consumption are Korsakoff's syndrome (KS) and alcohol-related dementia (ARD). There is limited evidence for benefit from memantine in the treatment of ARD, but stronger evidence for the use of high-dose parenteral thiamine in the progression of neuropsychiatric symptoms for WE. Accumulating evidence exists for pharmacological treatment in the prevention of hepatic encephalopathy. Rehabilitation of people with ARD may take several years, and requires an approach that addresses physical and psychosocial factors.

Morphine-element interactions - The influence of selected chemical elements on neural pathways associated with addiction

Addiction is a pressing social problem worldwide and opioid dependence can be considered the strongest and most difficult addiction to treat. Mesolimbic and mesocortical dopaminergic pathways play an important role in modulation of cognitive processes and decision making and, therefore, changes in dopamine metabolism are considered the central basis for the development of dependence. Disturbances caused by excesses or deficiency of certain elements have a significant impact on the functioning of the central nervous system (CNS) both in physiological conditions and in pathology and can affect the cerebral reward system and therefore, may modulate processes associated with the development of addiction. In this paper we review the mechanisms of interactions between morphine and zinc, manganese, chromium, cadmium, lead, fluoride, their impact on neural pathways associated with addiction, and on antinociception and morphine tolerance and dependence.

Post-trauma anhedonia is associated with increased substance use in a recently-traumatized population

Recreational substance use (SU) can emerge or worsen in the aftermath of psychological trauma. Anhedonia is one reason for this problematic SU. Symptoms of posttraumatic stress disorder (PTSD) that represent anhedonia (post-trauma anhedonia; PTA) have been consistently linked to SU disorders. However, no prospective studies have examined whether changes in PTA over time are associated with problematic SU in recently-traumatized people, which was the goal of this study. 165 men and women were recruited as part of a prospective PTSD study in the emergency department of a Level 1 trauma center. Clinical assessments of PTSD and SU were administered at three and six months post-trauma. Compared to participants with minimal SU at six months post-trauma, high substance users at six months post-trauma showed significant increases in PTA during the three to six month time period. This relationship was significant even after accounting for variance associated with other factors, including PTSD symptoms such as re-experiencing and hyperarousal. Participants who demonstrated increases in SU during this time also showed significant increases in PTA, unlike those who demonstrated consistently minimal/no SU during this time. These findings indicate that PTA may be a mechanism through which SU problems emerge in recently-traumatized individuals.

Ethanol consumption following mild traumatic brain injury is related to blood-brain barrier permeability

Several preclinical and clinical studies that deal with the neuropathological consequences of mild traumatic brain injury (mTBI) have focused on unraveling its effect on ethanol drinking behavior. Previous reports describe changes in ethanol consumption, both in animal models of mTBI as well as in patients, after concussive brain injury. However, the neurobiological mechanisms underlying this phenomenon are still poorly understood. In the present study, we used a unique model of mouse lines divergently selected for high (HA) or low (LA) swim stress-induced analgesia to examine the effect of mTBI on ethanol drinking behavior. In comparison with LA mice, their HA counterparts exhibited increased blood-brain barrier (BBB) permeability, lower basal alcohol preference, and lower level of stress-induced ethanol intake. Here, we showed that mTBI attenuates voluntary ethanol intake in LA, but not in HA mice. Interestingly, BBB disruption after mannitol infusion also decreases the level of ethanol drinking behavior in this line. We conclude that in alcohol-preferring LA mice, BBB disruption as a consequence of mTBI attenuates ethanol consumption. Our results suggest that the innate level of BBB integrity plays a pivotal role in regulation of ethanol consumption in mice showing differential endogenous opioid system activity.

Experimental Traumatic Brain Injury during Adolescence Enhances Cocaine Rewarding Efficacy and Dysregulates Dopamine and Neuroimmune Systems in Brain Reward Substrates

Although clinical studies identify traumatic brain injury (TBI) as a risk factor for the development of substance use disorder, much remains unknown about the possible underlying pathogenesis and age-specific effects. Thus, the aim of this study is to test the hypothesis that at an age of ongoing maturation, adolescent TBI alters elements of the reward pathway, resulting in increased sensitivity to the rewarding effects of a subthreshold dose of cocaine that does not induce significant behavioral changes in naïve, non-injured mice. Specifically, these results were derived from the combination of the controlled cortical impact model of TBI, performed on either adolescent (6 weeks) or young adult (8 weeks) mice, followed by the cocaine-induced conditioned place preference assay 2 weeks later. Using three-dimensional isosurface rendering and volumetric image analysis, TBI was found to induce neuromorphological changes such as decreased dendritic complexity and reduced spine density in brain regions essential for reward perception and processing of drug-induced euphoria. Further, we demonstrated that these neuronal changes may affect the differential expression of dopamine-associated genes. Our analysis also provided evidence for age-related differences in immune response and the distinct involvement of augmented microglial phagocytic activity in the remodeling of neuronal structures in the adolescent TBI brain. Our studies suggest that TBI during adolescence, a period associated with ongoing maturation of dopaminergic systems, may subsequently enhance the abuse liability of cocaine in adulthood.

Alcohol misuse and traumatic brain injury: a review of the potential roles of dopaminergic dysfunction and physiological underarousal post-injury

Although many researchers have demonstrated an increase in alcohol use following traumatic brain injury (TBI), there is also a body of research indicating that alcohol misuse predisposes one to injury and precedes TBI. Accordingly, various mechanisms have been proposed (e.g., self-medication, dampened levels of arousal, dopaminergic dysfunction, etc.) and variable results have emerged. This paper reviews the empirical evidence, for and against, TBI as a risk factor for alcohol misuse. In particular, this paper focuses on the brain-behavior relationships involved and examines the roles of physiological underarousal and dopaminergic dysfunction in the development of alcohol misuse after injury. Alcohol misuse impedes community reintegration among TBI survivors and creates additional rehabilitative challenges. Thus, in order to inform and improve treatment outcomes among this vulnerable population, a deeper understanding of the neural mechanisms implicated is needed.

Brain interrupted: Early life traumatic brain injury and addiction vulnerability

Recent reports provide evidence for increased risk of substance use disorders (SUD) among patients with a history of early-life traumatic brain injury (TBI). Preclinical research utilizing animal models of TBI have identified injury-induced inflammation, blood-brain barrier permeability, and changes to synapses and neuronal networks within regions of the brain associated with the perception of reward. Importantly, these reward pathway networks are underdeveloped during childhood and adolescence, and early-life TBI pathology may interrupt ongoing maturation. As such, maladaptive changes induced by juvenile brain injury may underlie increased susceptibility to SUD. In this review, we describe the available clinical and preclinical evidence that identifies SUD as a persistent psychiatric consequence of pediatric neurotrauma by discussing (1) the incidence of early-life TBI, (2) how preclinical studies model TBI and SUD, (3) TBI-induced neuropathology and neuroinflammation in the corticostriatal regions of the brain, and (4) the link between childhood or adolescent TBI and addiction in adulthood. In summary, preclinical research utilizes an innovative combination of models of early-life TBI and SUD to recapitulate clinical features and to determine how TBI promotes a risk for the development of SUD. However, causal processes that link TBI and SUD remain unclear. Additional research to identify and therapeutically target underlying mechanisms of aberrant reward pathway development will provide a launching point for TBI and SUD treatment strategies.

Robust Reconstruction of Fluorescence Molecular Tomography Based on Sparsity Adaptive Correntropy Matching Pursuit Method for Stem Cell Distribution

Fluorescence molecular tomography (FMT), as a promising imaging modality in preclinical research, can obtain the three-dimensional (3-D) position information of the stem cell in mice. However, because of the ill-posed nature and sensitivity to noise of the inverse problem, it is a challenge to develop a robust reconstruction method, which can accurately locate the stem cells and define the distribution. In this paper, we proposed a sparsity adaptive correntropy matching pursuit (SACMP) method. SACMP method is independent on the noise distribution of measurements and it assigns small weights on severely corrupted entries of data and large weights on clean ones adaptively. These properties make it more suitable for in vivo experiment. To analyze the performance in terms of robustness and practicability of SACMP, we conducted numerical simulation and in vivo mice experiments. The results demonstrated that the SACMP method obtained the highest robustness and accuracy in locating stem cells and depicting stem cell distribution compared with stagewise orthogonal matching pursuit and sparsity adaptive subspace pursuit reconstruction methods. To the best of our knowledge, this is the first study that acquired such accurate and robust FMT distribution reconstruction for stem cell tracking in mice brain. This promotes the application of FMT in locating stem cell and distribution reconstruction in practical mice brain injury models.

Traumatic Brain Injuries during Development: Implications for Alcohol Abuse

Traumatic brain injuries are strongly related to alcohol intoxication as by some estimates half or more of all brain injuries involve at least one intoxicated individual. Additionally, there is mounting evidence that traumatic brain injuries can themselves serve as independent risk factors for the development of alcohol use disorders, particularly when injury occurs during juvenile or adolescent development. Here, we will review the epidemiological and experimental evidence for this phenomenon and discuss potential psychosocial mediators including attenuation of negative affect and impaired decision making as well as neurochemical mediators including disruption in the glutamatergic, GABAergic, and dopaminergic signaling pathways and increases in inflammation.

Acute administration of catalase targeted to ICAM-1 attenuates neuropathology in experimental traumatic brain injury

Traumatic brain injury (TBI) contributes to one third of injury related deaths in the US. Treatment strategies for TBI are supportive, and the pathophysiology is not fully understood. Secondary mechanisms of injury in TBI, such as oxidative stress and inflammation, are points at which intervention may reduce neuropathology. Evidence suggests that reactive oxygen species (ROS) propagate blood-brain barrier (BBB) hyperpermeability and inflammation following TBI. We hypothesized that targeted detoxification of ROS may improve the pathological outcomes of TBI. Following TBI, endothelial activation results in a time dependent increase in vascular expression of ICAM-1. We conjugated catalase to anti-ICAM-1 antibodies and administered the conjugate to 8 wk old C57BL/6J mice 30 min after moderate controlled cortical impact injury. Results indicate that catalase targeted to ICAM-1 reduces markers of oxidative stress, preserves BBB permeability, and attenuates neuropathological indices more effectively than non-targeted catalase and anti-ICAM-1 antibody alone. Furthermore, the study of microglia by two-photon microscopy revealed that anti-ICAM-1/catalase prevents the transition of microglia to an activated phenotype. These findings demonstrate the use of a targeted antioxidant enzyme to interfere with oxidative stress mechanisms in TBI and provide a proof-of-concept approach to improve acute TBI management that may also be applicable to other neuroinflammatory conditions.