Relation between plasma brain-derived neurotrophic factor and nerve growth factor in the male patients with alcohol dependence

Alterations in Neurotrophins in Alcohol-Addicted Patients during Alcohol Withdrawal

BACKGROUND

Alcohol use disorder (AUD) is related to mental and somatic disorders that result in alcohol withdrawal syndrome (AWS), with 30% of AWS cases leading to life-threatening delirium tremens (DTs). Currently, studies do not support using any one biomarker in DTs. Neurotrophins affect neuromodulation, playing a role in the pathogenesis of AUD, AWS, and DTs.

METHODS

This review aims to summarize experimental and clinical data related to neurotrophins and S100B in neuroplasticity, as well as neurodegeneration in the context of AUD, AWS, and DTs. This work used publications that were selected based on the protocol consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.

RESULTS

The BDNF level could be a good candidate biomarker for relapse susceptibility, as it is significantly reduced during consumption and gradually increases during abstinence. GDNF influences AUD through its integral role in the function of dopaminergic neurons and ablates the return to alcohol-drinking behavior. NGF protects neurons from ethanol-induced cytotoxic damage and affects recovery from cognitive deficits after brain damage. The NT-3 level is decreased after alcohol exposure and is involved in compensatory mechanisms for cognitive decline in AUD. NT-4 affects oxidative stress, which is associated with chronic alcohol consumption. S100B is used as a biomarker of brain damage, with elevated levels in serum in AUD, and can protect 5-HT neurons from the damage caused by alcohol.

CONCLUSIONS

BDNF, GDNF, NT-3, NT-4, NGF, and S100B may be valuable markers for withdrawal syndrome. In particular, the most relevant is their association with the development of delirium complications. However, there are few data concerning some neurotrophins in AWS and DTs, suggesting the need for further research.

Expression Patterns of miRNAs in Egyptian Children with ADHD: Clinical Study with Correlation Analysis

ADHD has huge knowledge gaps concerning its etiology. MicroRNAs (miRNAs) provide promising diagnostic biomarkers of human pathophysiology and may be a novel therapeutic option. The aim was to investigate the levels of miR-34c-3p, miR-155, miR-138-1, miR-296-5p, and plasma brain-derived neurotrophic factor (BDNF) in a group of children with ADHD compared to neurotypicals and to explore correlations between these measures and some clinical data. The participants were children with ADHD in Group I (N = 41; age: 8.2 ± 2) and neurotypical ones in Group II (N = 40; age: 8.6 ± 2.5). Group I was subjected to clinical examination, the Stanford Binet intelligence scale-5, the preschool language scale, and Conner's parent rating scale-R. Measuring the expression levels of the miRNAs was performed by qRT-PCR for all participants. The BDNF level was measured by ELISA. The lowest scores on the IQ subtest were knowledge and working memory. No discrepancies were noticed between the receptive and expressive language ages. The highest scores on the Conner's scale were those for cognitive problems. Participants with ADHD exhibited higher plasma BDNF levels compared to controls (p = 0.0003). Expression patterns of only miR-34c-3p and miR-138-1 were downregulated with significant statistical differences (p˂0.01). However, expression levels of miR-296-5p showed negative correlation with the total scores of IQ (p = 0.03). MiR-34c-3p, miR-138-1, while BDNF showed good diagnostic potential. The downregulated levels of miR-34c-3p and miR-138-1, together with high BDNF levels, are suggested to be involved in the etiology of ADHD in Egyptian children. Gender differences influenced the expression patterns of miRNAs only in children with ADHD.

Stimulation of Neurite Outgrowth Using Autologous NGF Bound at the Surface of a Fibrous Substrate

Peripheral nerve injury still remains a major clinical challenge, since the available solutions lead to dysfunctional nerve regeneration. Even though autologous nerve grafts are the gold standard, tissue engineered nerve guidance grafts are valid alternatives. Nerve growth factor (NGF) is the most potent neurotrophic factor. The development of a nerve guidance graft able to locally potentiate the interaction between injured neurons and autologous NGF would be a safer and more effective alternative to grafts that just release NGF. Herein, a biofunctional electrospun fibrous mesh (eFM) was developed through the selective retrieval of NGF from rat blood plasma. The neurite outgrowth induced by the eFM-NGF systems was assessed by culturing rat pheochromocytoma (PC12) cells for 7 days, without medium supplementation. The biological results showed that this NGF delivery system stimulates neuronal differentiation, enhancing the neurite growth more than the control condition.

Plasma brain-derived neurotrophic factor (BDNF) in Egyptian children with attention deficit hyperactivity disorder

Background

To date, researchers do not fully understand what the aetiology of attention deficit hyperactivity disorder (ADHD) is. As a neurotrophin, the brain-derived neurotrophic factor (BDNF) contributes to the growth of neurons as well as to the efficiency and plasticity of the neuronal synapse, which suggests that it may be a contributing aetiological factor in ADHD. Therefore, we sought to investigate the relationship between ADHD and plasma BDNF, including whether there is an association between BDNF and the degree of severity of ADHD and with ADHD subtypes.

Results

We found significantly elevated plasma BDNF in ADHD subjects in comparison with healthy subjects, but differences among the three subtypes of ADHD did not reach statistical significance.

Conclusion

Compared with the control group, elevated plasma BDNF levels were found in the ADHD group, which suggests it may contribute to the aetiology of ADHD.

Brain-derived neurotrophic factor among patients with alcoholism

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is involved in neurogenesis and in the protection against oxidative damage and neuronal apoptosis. After exercise, there is an increased expression of this myokine, especially in skeletal muscle and brain. Low BDNF levels have been described in neurodegenerative diseases. Alcoholics show both muscle atrophy and brain atrophy. Thus, this study was performed in order to analyze serum BDNF levels among alcoholics and their associations with brain atrophy and muscle strength.

METHODS

Serum BDNF values were determined to 82 male alcoholics and 27 age-matched controls, and compared with handgrip strength, with the presence of brain atrophy, assessed by computed tomography, and with the intensity of alcoholism and liver function derangement.

RESULTS

BDNF levels and handgrip strength were significantly lower among patients. Handgrip strength was correlated with BDNF values, both in the whole population and in alcoholics, especially in patients over 59 years of age. BDNF was poorly related to liver dysfunction but showed no relationship with brain atrophy or age.

CONCLUSION

Chronic alcoholics show decreased BDNF serum levels that are related to muscle function impairment rather than to age, brain atrophy, liver dysfunction, or the amount of ethanol consumed.

Nerve Growth Factor, Stress and Diseases

Stress is a constant threat for homeostasis and is represented by different extrinsic and intrinsic stimuli (stressors, Hans Selye's "noxious agents"), such as aggressive behavior, fear, diseases, physical activity, drugs, surgical injury, and environmental and physiological changes. Our organisms respond to stress by activating the adaptive stress system to activate compensatory responses for restoring homeostasis. Nerve Growth Factor (NGF) was discovered as a signaling molecule involved in survival, protection, differentiation, and proliferation of sympathetic and peripheral sensory neurons. NGF mediates stress with an important role in translating environmental stimuli into physiological and pathological feedbacks since NGF levels undergo important variations after exposure to stressful events. Psychological stress, lifestyle stress, and oxidative stress are well known to increase the risk of mental disorders such as schizophrenia, major depressive disorders, bipolar disorder, alcohol use disorders and metabolic disorders such as metabolic syndrome. This review reports recent works describing the activity of NGF in mental and metabolic disorders related to stress.

Nutritional Ketosis as a Potential Treatment for Alcohol Use Disorder

Alcohol use disorder (AUD) is a chronic, relapsing brain disorder, characterized by compulsive alcohol seeking and disrupted brain function. In individuals with AUD, abstinence from alcohol often precipitates withdrawal symptoms than can be life threatening. Here, we review evidence for nutritional ketosis as a potential means to reduce withdrawal and alcohol craving. We also review the underlying mechanisms of action of ketosis. Several findings suggest that during alcohol intoxication there is a shift from glucose to acetate metabolism that is enhanced in individuals with AUD. During withdrawal, there is a decline in acetate levels that can result in an energy deficit and could contribute to neurotoxicity. A ketogenic diet or ingestion of a ketone ester elevates ketone bodies (acetoacetate, β-hydroxybutyrate and acetone) in plasma and brain, resulting in nutritional ketosis. These effects have been shown to reduce alcohol withdrawal symptoms, alcohol craving, and alcohol consumption in both preclinical and clinical studies. Thus, nutritional ketosis may represent a unique treatment option for AUD: namely, a nutritional intervention that could be used alone or to augment the effects of medications.

Nerve Growth Factor in Alcohol Use Disorders

The nerve growth factor (NGF) belongs to the family of neurotrophic factors. Initially discovered as a signaling molecule involved in the survival, protection, differentiation, and proliferation of sympathetic and peripheral sensory neurons, it also participates in the regulation of the immune system and endocrine system. NGF biological activity is due to the binding of two classes of receptors: the tropomyosin-related kinase A (TrkA) and the low-affinity NGF pan-neurotrophin receptor p75. Alcohol Use Disorders (AUD) are one of the most frequent mental disorders in developed countries, characterized by heavy drinking, despite the negative effects of alcohol on brain development and cognitive functions that cause individual’s work, medical, legal, educational, and social life problems. In addition, alcohol consumption during pregnancy disrupts the development of the fetal brain causing a wide range of neurobehavioral outcomes collectively known as fetal alcohol spectrum disorders (FASD). The rationale of this review is to describe crucial findings on the role of NGF in humans and animals, when exposed to prenatal, chronic alcohol consumption, and on binge drinking.

Growth Factors and Alcohol Use Disorder

Neurotrophic growth factors were originally characterized for their support in neuronal differentiation, outgrowth, and survival during development. However, it has been acknowledged that they also play a vital role in the adult brain. Abnormalities in growth factors have been implicated in a variety of neurological and psychiatric disorders, including alcohol use disorder (AUD). This work focuses on the interaction between alcohol and growth factors. We review literature suggesting that several growth factors play a unique role in the regulation of alcohol consumption, and that breakdown in these growth factor systems is linked to the development of AUD. Specifically, we focus on the brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), fibroblast growth factor 2 (FGF2), and insulin growth factor 1 (IGF-1). We also review the literature on the potential role of midkine (MDK) and pleiotrophin (PTN) and their receptor, anaplastic lymphoma kinase (ALK), in AUD. We show that alcohol alters the expression of these growth factors or their receptors in brain regions previously implicated in addiction, and that manipulations on these growth factors and their downstream signaling can affect alcohol-drinking behaviors in animal models. We conclude that there is a need for translational and clinical research to assess the therapeutic potential of new pharmacotherapies targeting these systems.

Evolution of BDNF serum levels during the first six months after alcohol withdrawal

OBJECTIVES

Brain-Derived Neurotrophic Factor (BDNF) has been associated with alcohol dependence and appear to vary after withdrawal, although the link with the withdrawal outcome on the long term is unknown. We aimed to assess the evolution of BDNF levels during the six months following withdrawal and determine the association with the status of alcohol consumption.

METHODS

Serum BDNF levels of alcohol-dependent patients (n = 248) and biological and clinical parameters were determined at the time of alcohol cessation (D0), 14 days (D14), 28 days (D28), and 2, 4, and 6 months after (M2, M4, M6).

RESULTS

Abstinence decreased during follow-up and was 31.9% after six months. BDNF levels increased by 14 days after withdrawal and remained elevated throughout the six-month period, independently of alcohol consumption. Serum BDNF levels evolved over time (p < 0.0001), with a correlation between BDNF and GGT levels. The prescription of baclofen at the time of withdrawal was associated with higher serum BDNF levels throughout the follow-up and that of anti-inflammatory drugs with lower BDNF levels.

CONCLUSIONS

A link between BDNF levels, liver function, and the inflammatory state in the context of alcohol abuse and not only with alcohol dependence itself is proposed.

BDNF levels and liver stiffness in subjects with alcohol use disorder: Evaluation after alcohol withdrawal

Background: Brain-derived neurotrophic factor (BDNF) plays a key role in the processes of withdrawal and addiction in alcohol use disorder (AUD), and is also involved in liver homeostasis. The role of BDNF in liver damage and its link with liver stiffness are not known. We hypothesize that serum BDNF levels are linked to changes in hepatic elasticity, both of which depend on variations in alcohol consumption.Objectives: We aimed to study the evolution of BDNF levels and changes in the liver stiffness (LS) of AUD subjects, within two months following withdrawal.Methods: We measured LS by FibroScan® (as an indicator of the degree of liver fibrosis), gamma glutamyl transferase (GGT) levels (as a nonspecific but sensitive marker of liver status) and serum BDNF levels of 62 alcohol-dependent subjects without previously identified liver complications. Measures were obtained at the time of withdrawal (M0) and two months later (M2). Results: BDNF levels increased after alcohol withdrawal and small variations of LS were observed. BDNF values increased significantly according to fibrosis stages measured by LS (p = .028 at M0), and were predicted by GGT levels in a regression model (p = .007 at M0 and p = .003 at M2).Conclusion: In AUD, BDNF levels were associated with measured LS when divided into fibrosis risk categories. Changes in LS and BDNF levels after alcohol withdrawal may be related to changes in homeostatic mechanisms, in addition to those of liver status.

An Observational Study of Serum Brain Derived Neurotrophic Factor Levels in Patients with Alcohol Dependence during Withdrawal

Brain-Derived Neurotrophic Factor (BDNF) is a neuropeptide that plays an important role in Central Nervous System development, plasticity, learning, and memory. Its role has been explored in alcohol-dependent patients, though the results have been inconclusive. Thus, we aimed to compare serum BDNF levels in alcohol-dependent patients during withdrawal with age and gender matched controls, and assess changes in BDNF levels in the initial abstinence period. BDNF levels of alcohol-dependent patients (n = 25) were compared with controls (n = 25) at baseline. Additionally, BDNF levels were measured in cases on days 5 and 10 of inpatient detoxification. BDNF levels of controls did not differ with cases on day 1, 5, or 10. But BDNF levels increased significantly during alcohol abstinence from baseline to day 10 (Pillai's Trace F = 3.753, p = .039, partial η² = 0.246), which may suggest its protective role. Thus, serum BDNF values may be potentially used as a biomarker to assess the abstinence state. However, longitudinal studies in different body samples is essential to better understand the role of BDNF in alcohol dependence.

Contribution of Neurotrophins to the Immune System Regulation and Possible Connection to Alcohol Addiction

The first references to neurotrophic factors date back to the middle of the 20th century when the nerve growth factor (NGF) was first discovered. Later studies delivered a large amount of data on neurotrophic factors. However, many questions regarding neurotrophin signaling still remain unanswered. One of the principal topics in neurotrophin research is their role in the immune system regulation. Another important research question is the possible involvement of neurotrophin signaling in the pathological processes associated with alcoholism. Among known neurotrophins, NT-4 remains the least studied and appears to be involved in alcoholism and chronic stress pathogenesis. In this review we discuss known neurotrophin signaling cascades mediated by different neurotrophin receptors, as well as provide a generalization of the data regarding the influence of neurotrophins NGF, BDNF, and NT-4 on the immune system and their potential contribution to the pathogenesis of alcoholism.

Human Plasma BDNF Is Associated With Amygdala-Prefrontal Cortex Functional Connectivity and Problem Drinking Behaviors

BACKGROUND

Preclinical studies suggest that decreased levels of brain-derived neurotrophic factor in the amygdala play a role in anxiety and alcohol use disorder. The association between brain-derived neurotrophic factor levels and amygdala function in humans with alcohol use disorder is still unclear, although neuroimaging studies have also implicated the amygdala in alcohol use disorder and suggest that alcohol use disorder is associated with disrupted functional connectivity between the amygdala and prefrontal cortex during aversive states.

METHODS

The current study investigated whether plasma brain-derived neurotrophic factor levels in individuals with and without alcohol use disorder (n = 57) were associated with individual differences in amygdala reactivity and amygdala-prefrontal cortex functional connectivity during 2 forms of aversive responding captured via functional magnetic resonance imaging: anxiety elicited by unpredictable threat of shock and fear elicited by predictable threat of shock. We also examined whether brain-derived neurotrophic factor and brain function were associated with binge drinking episodes and alcohol use disorder age of onset.

RESULTS

During anxiety, but not fear, lower levels of plasma brain-derived neurotrophic factor were associated with less connectivity between the left amygdala and the medial prefrontal cortex and the inferior frontal gyrus. In addition, within individuals with alcohol use disorder (only), lower levels of brain-derived neurotrophic factor and amygdala-medial prefrontal cortex functional connectivity during anxiety were associated with more binge episodes within the past 60 days and a lower age of alcohol use disorder onset. There were no associations between brain-derived neurotrophic factor levels and focal amygdala task reactivity.

CONCLUSIONS

Together, the results indicate that plasma brain-derived neurotrophic factor levels are related to amygdala circuit functioning in humans, particularly during anxiety, and these individual differences may relate to drinking behaviors.

A review of peripheral brain-derived neurotrophic factor levels in alcohol-dependent patients: Current understanding

Brain-derived neurotrophic factor (BDNF) plays a crucial role in neuroplasticity of the brain, and its role in alcohol dependence has been explored in the recent past. Animal studies suggest that BDNF may function as a protective factor in transition from social drinking to an alcohol use disorder. However, clinical studies have not been able to establish similar findings and have shown mixed results. In order to obtain a comprehensive understanding, the current review aims to evaluate the existing literature on the role of BDNF in alcohol dependence. Articles were retrieved using search engines PubMed and Google Scholar. Original research studies focusing on human participants, published in English till October 2018 were reviewed. Studies which measured BDNF levels in serum or plasma or both were included in this study. A total of 13 studies were found which compared BDNF levels in alcohol-dependent patients with control population. The studies have mixed findings. Seven studies measured BDNF levels across the abstinence period, and most of the studies show improving BDNF levels across the abstinence. The current review supports the notion that BDNF plays an important role in the neuroplasticity of alcohol dependence. However, it is premature at this stage to draw conclusions that BDNF may be used as a biomarker, as there have been inconclusive findings when compared with control population. Future studies with longer follow-ups, larger sample size, comparing early and late periods of alcohol abstinence are required for better understanding of the role BDNF in alcohol dependence.

Peripheral Blood Brain-Derived Neurotrophic Factor as a Biomarker of Alzheimer's Disease: Are There Methodological Biases?

Mounting evidence that alterations in brain-derived neurotrophic factor (BDNF) levels and signaling may be involved in the etiopathogenesis of Alzheimer's disease (AD) has suggested that its blood levels could be used as a biomarker of the disease. However, higher, lower, or unchanged circulating BDNF levels have all been described in AD patients compared to healthy controls. Although the reasons for such different findings are unclear, methodological issues are likely to be involved. The heterogeneity of participant recruitment criteria and the lack of control of variables that influence circulating BDNF levels regardless of dementia (depressive symptoms, medications, lifestyle, lack of overlap between serum and plasma, and experimental aspects) are likely to bias result and prevent study comparability. The present work reviews a broad panel of factors, whose close control could help reduce the inconsistency of study findings, and offers practical advice on their management. Research directed at elucidating the weight of each of these variables and at standardizing analytical methodologies is urgently needed.

ProBDNF/p75NTR/sortilin pathway is activated in peripheral blood of patients with alcohol dependence

Alcohol dependence is a worldwide problem with a great social and economic burden in many countries. A number of studies have suggested that BDNF (mature BDNF) and its precursor (proBDNF) play important roles in the alcohol dependence. However, what roles of the mBDNF/proBDNF pathways play during the pathological process of alcohol dependence are not clearly understood. In our clinical study, peripheral blood was sampled from 30 male patients with alcohol dependence and 50 healthy males (as control). The protein levels of proBDNF, p75NTR, sortilin, mBDNF, TrkB and mRNA levels of BDNF, p75NTR, sortilin, and TrkB were detected in the peripheral blood in our study. We found that the protein levels of proBDNF and p75NTR were increased, but not the sortilin protein level; while the TrkB protein level was decreased in the alcohol dependence patients compared with healthy controls. Moreover, the mRNA levels of p75NTR and sortilin from the lymphocytes were slightly increased; while BDNF and TrkB were significantly decreased. The ELISA results of mBDNF and TrkB were declined in the alcohol dependence group. The levels of mBDNF and TrkB were negatively correlated with the average amount of daily ethanol consumption, and the levels of proBDNF, p75NTR and sortilin were positively correlated with the average amount of ethanol consumption per day. The ratio of proBDNF to mBDNF was altered in alcohol dependence patients. The balance between the proBDNF/p75NTR and mBDNF/TrkB signalling pathways appeared dysregulated in alcohol dependence. Our results suggested that both pathways may participate in the complex processes of alcohol dependence.

Decreased plasma concentrations of BDNF and IGF-1 in abstinent patients with alcohol use disorders

The identification of growth factors as potential biomarkers in alcohol addiction may help to understand underlying mechanisms associated with the pathogenesis of alcohol use disorders (AUDs). Previous studies have linked growth factors to neural plasticity in neurocognitive impairment and mental disorders. In order to further clarify the impact of chronic alcohol consumption on circulating growth factors, a cross-sectional study was performed in abstinent AUD patients (alcohol group, N = 91) and healthy control subjects (control group, N = 55) to examine plasma concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1) and IGF-1 binding protein-3 (IGFBP-3). The association of these plasma peptides with relevant AUD-related variables and psychiatric comorbidity was explored. The alcohol group was diagnosed with severe AUD and showed an average of 13 years of problematic use and 10 months of abstinence at the moment of participating in the study. Regarding common medical conditions associated with AUD, we observed an elevated incidence of alcohol-induced liver and pancreas diseases (18.7%) and psychiatric comorbidity (76.9%). Thus, AUD patients displayed a high prevalence of dual diagnosis (39.3%) [mainly depression (19.9%)] and comorbid substance use disorders (40.7%). Plasma BDNF and IGF-1 concentrations were significantly lower in the alcohol group than in the control group (p<0.001). Remarkably, there was a negative association between IGF-1 concentrations and age in the control group (r = -0.52, p<0.001) that was not found in the alcohol group. Concerning AUD-related variables, AUD patients with liver and pancreas diseases showed even lower concentrations of BDNF (p<0.05). In contrast, the changes in plasma concentrations of these peptides were not associated with abstinence, problematic use, AUD severity or lifetime psychiatric comorbidity. These results suggest that further research is necessary to elucidate the role of BDNF in alcohol-induced toxicity and the biological significance of the lack of correlation between age and plasma IGF-1 levels in abstinent AUD patients.

Serum brain-derived neurotrophic factor, glial-derived neurotrophic factor, nerve growth factor, and neurotrophin-3 levels in children with attention-deficit/hyperactivity disorder

It has been suggested that neurotrophins are involved in the etiopathogenesis of attention-deficit/hyperactivity disorder (ADHD). This study aimed to investigate whether there are differences in serum brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and neurotrophin-3 (NTF3) levels between children with ADHD and healthy controls. A total of 110 treatment-naive children with the combined presentation of ADHD and 44 healthy controls aged 8-18 years were enrolled in this study. The severity of ADHD symptoms was determined by scores on the Conners' Parent Rating Scale-Revised Short and Conners' Teacher Rating Scale-Revised Short. The severity of depression and anxiety symptoms of the children were evaluated by the self-report inventories. Serum levels of neurotrophins were measured using commercial enzyme-linked immunosorbent assay kits. The multivariate analysis of covariance (MANCOVA) revealed a significant main effect of groups in the levels of serum neurotrophins, an effect that was independent of age, sex, and the severity of the depression and anxiety. The analysis of covariance (ANCOVA) indicated that the mean serum GDNF and NTF3 levels of ADHD patients were significantly higher than that of controls. However, serum BDNF and NGF levels did not show any significant differences between groups. No correlations between the levels of serum neurotrophins and the severity of ADHD were observed. These results suggest that elevated serum GDNF and NTF3 levels may be related to ADHD in children.

Neuroimmune Interface in the Comorbidity between Alcohol Use Disorder and Major Depression

Bidirectional communication links operate between the brain and the body. Afferent immune-to-brain signals are capable of inducing changes in mood and behavior. Chronic heavy alcohol drinking, typical of alcohol use disorder (AUD), is one such factor that provokes an immune response in the periphery that, by means of circulatory cytokines and other neuroimmune mediators, ultimately causes alterations in the brain function. Alcohol can also directly impact the immune functions of microglia, the resident immune cells of the central nervous system (CNS). Several lines of research have established the contribution of specific inflammatory mediators in the development and progression of depressive illness. Much of the available evidence in this field stems from cross-sectional data on the immune interactions between isolated AUD and major depression (MD). Given their heterogeneity as disease entities with overlapping symptoms and shared neuroimmune correlates, it is no surprise that systemic and CNS inflammation could be a critical determinant of the frequent comorbidity between AUD and MD. This review presents a summary and analysis of the extant literature on neuroimmune interface in the AUD–MD comorbidity.

Serum levels of brain-derived neurotrophic factor in alcohol-dependent patients receiving high-dose baclofen

The neurotrophin brain-derived neurotrophic factor (BDNF) has been suggested to be involved in the development and maintenance of addictive and other psychiatric disorders. Also, interactions of γ-aminobutyric acid (GABA)-ergic compounds and BDNF have been reported. The objective of this study was to investigate serum levels of BDNF over time in alcohol-dependent patients receiving individually titrated high-dose treatment (30-270mg/d) with the GABA-B receptor agonist baclofen or placebo for up to 20 weeks. Serum levels of BDNF were measured in patients of the baclofen/placebo group at baseline (t0), 2 weeks after reaching individual high-dose of baclofen/placebo treatment (t1) and after termination of study medication (t2) in comparison to carefully matched healthy controls. No significant differences in serum levels of BDNF between the baclofen and the placebo group or healthy controls were found at t0, t1, or at t2. Based on these findings, it seems unlikely that baclofen exerts a direct effect on serum levels of BDNF in alcohol-dependent patients. Future studies are needed to further explore the mechanism of action of baclofen and its possible relationship to BDNF in alcohol use disorders.

Increased serum neurotrophin levels related to alcohol use disorder in a young population sample

BACKGROUND

The diagnosis of alcohol use disorder is based on clinical signs and on the measurement of biological markers. However, these markers are neither sufficiently sensitive, nor specific enough, for determining the effects of alcohol abuse on the central nervous system. Serum neurotrophins are important regulators of neural survival, development, function, and plasticity and have been found to be reduced in alcohol use disorder. The aim of this study was to investigate the alterations in serum neurotrophin levels (brain-derived neurotrophic factor [BDNF], glial-derived neurotrophic factor [GDNF], and nerve growth factor [NGF]) in alcohol use disorder in a young population, and thus possibly representing the early stages of the illness.

METHODS

This is a cross-sectional study, nested in a population-based study of people aged 18 to 35, involving 795 participants. The participants responded to the CAGE questionnaire, and a CAGE score of ≥2 was considered to be a positive screen for the abuse/dependence or moderate to severe alcohol use disorder. Serum BDNF, GDNF, and NGF levels were measured by ELISA.

RESULTS

In the CAGE ≥ 2 group, GDNF (p ≤ 0.001) and NGF (p ≤ 0.001) serum levels were significantly increased, and the BDNF elevation was near a statistical significance (p = 0.068) when compared to the CAGE < 2 group. A significantly positive correlation was observed only in the CAGE ≥ 2 group for BDNF/GDNF (r = 0.37, p < 0.001) and GDNF/NGF (r = 0.84, p < 0.001) levels. The correlation between the NGF and BDNF levels was significantly positive in both groups (r = 0.28, p < 0.001 for the CAGE < 2 group, and r = 0.30, p = 0.008 for the CAGE ≥ 2 group).

CONCLUSIONS

These results suggest that elevated neurotrophins are candidate markers for the early stages of alcohol misuse.

Effects of cigarette smoking and alcohol use on neurocognition and BDNF levels in a Chinese population

OBJECTIVE

Few studies have examined the potential interactive effect of both smoking and drinking on cognition. Brain-derived neurotrophic factor (BDNF) plays a critical role in cognition. This is the first study to examine the neurocognitive consequences of cigarette smoking combined with chronic alcohol consumption and their relationship to serum BDNF levels in a Chinese Han population.

MATERIALS AND METHODS

We recruited 191 healthy male subjects, including 47 isolated smokers, 31 isolated chronic alcohol users, 58 combined smokers and chronic alcohol users, and 55 non-smokers and non-alcohol users. We then compared the repeatable battery for the assessment of neuropsychological status (RBANS) scores and serum BDNF levels in these four groups.

RESULTS

When compared to the non-smoking + non-alcohol-using group, the smoking group performed worse on immediate memory, attention, language, and RBANS total score. There were no significant differences in the RBANS scores between the alcohol-using group and non-smoking + non-alcohol-using group, or between the smoking group and smoking + alcohol-using group. We did not find an association between BDNF and smoking or drinking status or between BDNF and cognitive performance. In the smoking group, there was a significant correlation between BDNF and carbon monoxide concentration, and between BDNF and the Fagerstrom Test for Nicotine Dependence (FTND) total score.

CONCLUSIONS

Our results suggest that smoking is associated with cognitive decline, but not with BDNF levels in a normal population. However, smoking severity is positively associated with BDNF levels. Concomitant alcohol use does not worsen the cognitive decline caused by smoking.

Catheter Ablation of Atrial Fibrillation Raises the Plasma Level of NGF-β Which Is Associated with Sympathetic Nerve Activity

PURPOSE

The expression of nerve growth factor-β (NGF-β) is related to cardiac nerve sprouting and sympathetic hyper innervation. We investigated the changes of plasma levels of NGF-β and the relationship to follow-up heart rate variability (HRV) after radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF).

MATERIALS AND METHODS

This study included 147 patients with AF (117 men, 55.8±11.5 years, 106 paroxysmal AF) who underwent RFCA. The plasma levels of NGF-β were quantified using double sandwich enzyme linked immunosorbent assay method before (NGF-βpre) and 1 hour after RFCA (NGF-βpost-1 hr). HRV at pre-procedure (HRVpre), 3 months (HRVpost-3 mo), and 1 year post-procedure (HRVpost-1 yr) were analyzed and compared with plasma levels of NGF-β.

RESULTS

1) The plasma levels of NGF-β significantly increased after RFCA (20.05±11.09 pg/mL vs. 29.60±19.43 pg/mL, p<0.001). The patients who did not show increased NGF-βpost-1 hr were older (p=0.023) and had greater left atrial volume index (p=0.028) than those with increased NGF-βpost-1 hr. 2) In patients with NGF-βpre>18 pg/mL, low frequency components (LF)/high-frequency components (HF) (p=0.003) and the number of atrial premature contractions (APCs, p=0.045) in HRVpost-3 mo were significantly higher than those with ≤18 pg/mL. 3) The LF/HF at HRVpost-3 mo was linearly associated with the NGF-βpre (B=4.240, 95% CI 1.114-7.336, p=0.008) and the NGF-βpost-1 hr (B=7.617, 95% CI 2.106-13.127, p=0.007). 4) Both NGF-βpre (OR=1.159, 95% CI 1.045-1.286, p=0.005) and NGF-βpost-1 hr (OR=1.098, 95% CI 1.030-1.170, p=0.004) were independent predictors for the increase of LF/HF at HRVpost-3 mo.

CONCLUSION

AF catheter ablation increases plasma level of NGF-β, and high plasma levels of NGF-βpre was associated with higher sympathetic nerve activity and higher frequency of APCs in HRVpost-3 mo.

Serum brain-derived neurotrophic factor levels in relation to comorbid depression and cytokine levels in Nepalese men with alcohol-use disorders

Neurodegenerative and inflammatory processes are involved separately in major depression (MD) and alcohol-use disorders (AUD). Little is known about the nature of this relationship in the context of comorbid AUD and depression disorders. In this study, we determined brain-derived neurotrophic factor (BDNF) serum levels in patients with AUD and tested whether BDNF levels were related to history of major depression, recent depressive symptoms, AUD severity, and TNF-α and IL-6 levels. Nepalese male AUD inpatients (N=152) abstinent from alcohol for an average of 34 days were administered structured interviews to assess depression symptoms and pattern and extent of alcohol use, and to generate research diagnoses for AUD and MD. AUD severity was assessed by scores on the Alcohol Use Disorder Identification Test. Serum BDNF and cytokines were measured using ELISA and multiplex technology, respectively. Although serum BDNF levels were unrelated to MD history, patients with recent depressive symptoms (n=42) had lower (mean±SD) BDNF serum levels compared to those without (n=110) (21.6±8.1 ng/mL vs. 26.0±9.6 ng/mL; p=0.010), and patients with higher AUD severity and binge-drinking patterns had higher mean serum BDNF levels compared to lower AUD severity and non-binging (25.9±9.7 ng/mL vs. 22.1±8.7 ng/mL; p=0.022 and 25.7±9.3 vs. 21.8±9.7 ng/mL; p=0.029, respectively). Positive correlations were present between BDNF and TNF-α (r=0.39, p<0.001) and IL-6 (r=0.2, p=0.027). In particular, TNF-α levels were predictive of BDNF levels after controlling for confounders (B=0.3 [95% CI=0.2-0.5], p<0.001). These findings show that in alcohol-using populations, peripheral BDNF levels are related to severity of AUD as well as presence of depressive symptoms. The significant associations between inflammatory and neurotrophic factors may have implications for neuroadaptive changes during recovery from AUD.

Brain derived neurotrophic factor and cognitive status: the delicate balance among people living with HIV, with and without alcohol abuse

INTRODUCTION

The advent of combination antiretroviral therapy(cART) has lead to a significant reduction in morbidity and mortality among people living with HIV(PLWH). However, HIV-associated neurocognitive disorders (HAND) still remain a significant problem. One possible mechanism for the persistence of these disorders is through the effect of HIV on brain-derived neurotrophic factor (BDNF). BDNF is influenced by various factors including hazardous alcohol use (HAU), which is prevalent among PLWH. This study attempts to elucidate the relationships between HAU, BDNF and HAND.

METHODS

Cross-sectional analyses were conducted on a sample of 199 hazardous alcohol users and 198 non-HAU living with HIV. Members of each group were matched according to sociodemographic characteristics and CD4 count. Research procedures included validated questionnaires, neuropsychological assessments and a blood sample to obtain BDNF and immune measurements.

RESULTS

Hazardous alcohol users showed either significantly lower or significantly higher BDNF levels compared to the Non-hazardous (OR=1,4; 95% CI: 1-2.1, p = 0.003). Therefore, for additional analyses, subjects were categorized based on BDNF values in: Group 1 < 4000, Group 2: 4001-7,999 (reference group), and Group 3 for those >8,000 pg/mL. Groups 1 and 3 performed significantly worse than those in Group 2 in the domains of processing speed, auditory-verbal and visuospatial learning and memory. Multivariate analyses confirmed that HAU and BDNF are significant contributors of HAND.

CONCLUSION

Our findings offer novel insights into the relationships between BDNF, and alcohol use among PLWH. Our results also lend support to expanding clinical movement to use BDNF as an intervention target for PLWH, in those with evidence of deficiencies, and highlight the importance of including HAUat the inception of clinical trials.

Oxidative stress and BDNF as possible markers for the severity of crack cocaine use in early withdrawal

RATIONALE

An important goal of addiction research is to discover neurobiological markers that could predict the severity of addiction and help to determine appropriate treatment. Brain-derived neurotrophic factor (BDNF) and thiobarbituric acid reactive substances (TBARS) are being related to cerebral plasticity and impairment caused by substance abuse.

OBJECTIVES

This study aims to evaluate alteration of TBARS and BDNF levels among crack cocaine users during early drug withdrawal and its relationship to severity of drug use.

METHODS

Forty-nine adults crack cocaine users were recruited at a public psychiatric hospital with a specialized addiction treatment unit. Blood sample was collected at intake and discharge for the analysis of TBARS and BDNF measures. Information about drug use was assessed by the Addiction Severity Index 6th Version (ASI-6). Detailed information about crack cocaine use was obtained through the "Profile of the crack cocaine user." Severity of crack use was estimated using information from age of first crack use, years of crack use, and crack rocks used in the previous 30 days.

RESULTS

There is a positive correlation between TBARS levels and severity of crack cocaine use (R = 0.304, p = 0.04) and a negative correlation between BDNF and severity of crack cocaine use (R = -0.359, p = 0.01) at discharge. Also, we found an inverse correlation between TBARS and BDNF levels (R = -0.294, p = 0.004) at discharge.

CONCLUSIONS

Our findings suggest that BDNF and TBARS could be possible markers for the severity of drug use. Further studies may show how those markers could be related to staging, prognosis, and treatment in crack cocaine dependence.

Effects of olive leaf polyphenols on male mouse brain NGF, BDNF and their receptors TrkA, TrkB and p75

In this study, we evaluated, in the mouse, the effects of 20 mg/kg i.p. daily administration for 15 consecutive days of a blend of polyphenols, containing mostly oleuropein, extracted from the olive leaves (Olea europaea) on brain nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and on the expression of their receptors, TrkA, TrkB and p75. Polyphenols decreased the levels of reduced glutathione (GSH) and increased the levels of NGF and BDNF in the serum. In the brain, we found decreased levels of NGF and BDNF in the hippocampus and striatum but elevated levels of NGF in the olfactory lobes and hypothalamus and again BDNF potentiation in the olfactory lobes. No changes in TrkA, TrkB and p75 expression were observed. In conclusion, olive polyphenols may not only elicit an activation of the rodent olfactory system by increasing the levels of NGF and BDNF but also be stressing for the animal by reducing both the levels of hippocampal NGF/BDNF and serum GSH and increasing serum levels of NGF and BDNF.

Increase in brain-derived neurotrophic factor expression in early crack cocaine withdrawal

Recent reports suggest that brain-derived neurotrophic factor (BDNF) could be a biomarker for relapse, drug craving and withdrawal severity. In particular, elevated BDNF levels among former cocaine users have been associated with higher rates of relapse in 90 d. However, no data are available on BDNF levels at baseline and during crack cocaine withdrawal. This study evaluated BDNF among crack cocaine users during inpatient treatment, before and after withdrawal, vs. healthy controls. Clinical correlates with changes in BDNF levels were also assessed. Serum BDNF was evaluated in 49 male crack users on the first and last days of hospitalization and in 97 healthy controls. Serum BDNF was assayed using a sandwich ELISA kit. BDNF levels were significantly lower upon admission when compared to controls, even after adjustment for age, length of inpatient treatment, number of crack rocks used in the last 30 d, years of crack use and interaction between the latter two variables. At discharge, BDNF levels between patients and controls were similar. Number of crack rocks used in the last 30 d and years of crack use were inversely correlated with the outcome. Our findings show that BDNF levels increase during early crack cocaine withdrawal, at an inverse correlation with number of crack rocks used in the last 30 d and years of crack use.

Plasma BDNF levels are correlated with aggressiveness in patients with amnestic mild cognitive impairment or Alzheimer disease

In the present study, we examined whether neuropsychiatric symptoms were correlated with plasma brain-derived neurotrophic factor (BDNF) levels as a state marker or were associated with the BDNF polymorphism Val66Met in patients with amnestic mild cognitive impairment (A-MCI) or Alzheimer disease (AD). One hundred and seventy-six outpatients with AD (n = 129) or A-MCI (n = 47) were selected and their plasma BDNF concentrations measured. Next, we investigated the correlation between the plasma BDNF level and the Behavioral Pathology in Alzheimer Disease (Behave-AD) subscale scores, which reflect neuropsychiatric symptoms. We also compared the plasma BDNF level and the Behave-AD subscale scores among the BDNF Val66Met genotypic groups. Among the seven Behave-AD subscale scores, aggressiveness was positively correlated with the plasma BDNF level (ρ = 0.237, P < 0.005), but did not differ significantly among the three BDNF Val66Met genotypic groups. The Behave-AD total and other subscale scores did not differ significantly among the BDNF Val66Met genotypic groups and were not associated with the plasma BDNF level. Moreover, the plasma BDNF level did not differ significantly among the three BDNF Val66Met genotypic groups or between patients with A-MCI and those with AD. The plasma BDNF level was robustly correlated with aggressiveness, implying that the plasma BDNF level might be useful as a behavioral state marker in patients with AD or A-MCI.

Serum levels of brain-derived neurotrophic factor in patients with internet use disorder

Internet use disorder (IUD) is characterised by excessive internet gaming use and has temporarily been conceptualised as a behavioural addiction. Since brain-derived neurotrophic factor (BDNF) has been hypothesised to be involved in the development and maintenance of addictive disorders, we investigated BDNF expression in IUD. We measured BDNF serum levels in male patients with IUD (n=11) and individually matched healthy controls (n=10). There was no significant difference in BDNF serum levels of patients with IUD in comparison to control subjects. Serum levels of BDNF were not correlated with severity of IUD or clinical and demographic variables in our study. These preliminary findings possibly suggest a different underlying pathophysiology in IUD compared to addictive disorders. Thus, further studies are needed to clarify, whether IUD represents an addictive spectrum disorder, an impulse control disorder or finally an individual diagnostic entity that overlaps with both disease categories.

Serum brain-derived neurotrophic factor and nerve growth factor concentrations change after alcohol withdrawal: preliminary data of a case-control comparison

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are involved in neuroadaptation and foster survival of central and peripheral neurons. In this study, we addressed the question whether BDNF and NGF serum concentrations change during subacute alcohol withdrawal in patients with alcohol dependence compared to healthy controls.

METHODS

Fifteen patients (age 48.6 ± 7 years) and 15 healthy age-matched controls (age 48.8 ± 7 years) participated consecutively in a 2-week withdrawal study.

RESULTS

Mean BDNF levels (7.8 ng/ml, IQR = 4.4-10.7 vs. 16.5 ng/ml, IQR = 13.9-25.6; Z = -3.8, p < 0.0001) and NGF levels (5.8 pg/ml, IQR = 3.8-13.0 vs. 18.4 pg/ml, IQR = 10.9-25.1; Z = -2.5, p = 0.012) were significantly decreased in alcohol-dependent subjects when compared to healthy matched controls. NGF concentrations decreased significantly from day 3 to day 14 (Z = -2.36; p = 0.019). Mean BDNF concentrations showed a tendency to increase after withdrawal from day 3 to day 14 (Z = 1.7; p = 0.078).

CONCLUSION

Decreased NGF and BDNF concentrations in patients suffering from alcohol dependence, which stabilize after physical withdrawal, are in line with withdrawal symptoms and neurological risk factors. In turn, increase of BDNF after acute withdrawal might be connected to neurobiological and behavioral stabilization.

Serum and plasma brain-derived neurotrophic factor (BDNF) in abstinent alcoholics and social drinkers

Although the effects of alcohol on brain-derived neurotrophic factor (BDNF) have been extensively studied in rodents, BDNF levels have rarely been measured in abstinent, alcohol-dependent (AD) individuals. Interpretation of reported group comparisons of serum BDNF levels is difficult due to limited information regarding analytical variance, biological variability, and the relative contribution of platelet and plasma pools to serum BDNF. Analytical variance (intra- and inter-assay coefficients of variation) of the enzyme-linked immunosorbent assay (ELISA) was characterized. Within- and between-subject variability, and group differences in serum and plasma BDNF, was assessed on three separate days in 16, 4-week abstinent AD individuals (7M/9F) and 16 social drinkers (SDs; 8M/8F). Significantly higher mean (±sd) serum BDNF levels were observed for the AD group compared to the SD (p = 0.003). No significant difference in mean baseline plasma BDNF levels was observed between AD and SD groups. The low analytical variance, high day-to-day within-individual stability and the high degree of individuality demonstrates the potential clinical utility of measuring serum BDNF levels. The low correlations that we observed between plasma and serum levels are congruent with their representing separate pools of BDNF. The observation of higher basal serum BDNF in the AD group without a concomitant elevation in plasma BDNF levels indicates that the elevated serum BDNF in AD patients is not due to greater BDNF exposure. Further research is warranted to fully elucidate mechanisms underlying this alteration and determine the utility of serum BDNF as a predictor or surrogate marker of chronic alcohol abuse.

Plasma brain-derived neurotrophic factor in hemodialysis patients

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is a neurotrophin which modulates neuronal survival and proliferation. Recently, plasma BDNF is associated with inflammatory conditions. The present study was to investigate the changes of the plasma BDNF level in hemodialysis patients and to evaluate the relationship between the plasma BDNF and uremic inflammation.

METHOD

We measured the plasma BDNF, serum IL-2, IL-4, IFN-γ and TNF-α in hemodialysis patients and control subjects. In addition, we investigated the associations of the plasma BDNF with clinical or biochemical parameters.

RESULTS

The plasma BDNF level was significantly higher in hemodialysis patients than in the control subjects (median, 312.3 vs. 630.3 pg/ml, p < 0.05). In subgroup analysis, hemodialysis patients with diabetes showed higher values of the plasma BDNF than the patients without diabetes. However, there were no significant differences in age and gender subgroups of the hemodialysis patients. The logBDNF was positively correlated with hs-CRP and IFN-γ, and negatively correlated with serum albumin. In multivariate regression analysis, the logBDNF was independently associated with the presence of diabetes (β-coefficient = 0.399, p = 0.041) and IFN-γ (β-coefficient = 0.538, p = 0.003).

CONCLUSION

The plasma BDNF may increase in hemodialysis patients, and more prominently in the patients with diabetes. Furthermore, the plasma BDNF might reflect inflammatory condition in hemodialysis patients.

Altered serum levels of brain-derived neurotrophic factor in patients with pathological gambling

BACKGROUND

Brain-derived neurotrophic factor (BDNF) plays important roles in neurotransmitter release and synaptic plasticity and has been hypothesized to be involved in the development and maintenance of addictive disorders. The objective of this study was to investigate alterations of BDNF expression in a non-substance-related addiction, i.e. pathological gambling (PG).

METHODS

Serum levels of BDNF were assessed in male patients with PG (n = 14) and healthy control subjects (n = 13) carefully matched for sex, age, body mass index, smoking status and urbanicity. Symptoms and severity of PG were measured by the adapted form of the Yale-Brown Obsessive-Compulsive Scale.

RESULTS

BDNF serum levels were significantly increased in patients with PG in comparison to healthy control subjects (p = 0.016). There were no significant correlations between BDNF serum levels and severity of PG or clinical and demographic variables.

CONCLUSIONS

Our results show alterations of BDNF serum levels in patients suffering from a behavioural addiction and suggest that non-substance-related addictions like PG might be associated with neuroendocrinological changes similar to the changes observed in substance-related addictions.

Serum NPY and BNDF response to a behavioral stressor in alcohol-dependent and healthy control participants

RATIONALE

Neuropeptide Y (NPY) and brain-derived neurotrophic factor (BDNF) have been implicated in both the stress response and alcohol addiction. However, few studies have assessed the NPY and BDNF response to stress in alcohol-dependent participants and the concurrent measure of NPY and BDNF has not been reported in human participants.

OBJECTIVE

The purpose of this study was to concurrently assess serum NPY and BDNF, as well as adrenocorticotropin (ACTH) and cortisol, in control and race- and aged-matched abstinent alcohol-dependent participants in response to a stress-inducing public-speaking task.

METHODS

Basal and post-stress serum values of NPY and BDNF, as well as ACTH and cortisol, were assessed in 14 abstinent alcohol-dependent and ten healthy control male participants.

RESULTS

Basal measures were stable over short periods of time and stress induced a significant increase in both NPY (p = 0.002) and BDNF (p = 0.006) as well as ACTH (p < 0.001) and cortisol (p < 0.007). Alcohol-dependent and control groups did not significantly differ on any basal or stress-induced measure. Basal and delta responses of NPY and BDNF were not significantly correlated, and delta peak responses of NPY and BDNF did not correlate with one another or with their respective ACTH and cortisol responses.

CONCLUSIONS

These findings reveal that both serum NPY and BDNF are responsive to behavioral stressors, although their regulatory mechanisms appear to differ from one another and those of the hypothalamic-pituitary-adrenal axis. Differences in basal and stress-induced responses of NPY and BDNF were not supported between control and abstinent alcohol-dependent subjects.

Voluntary exercise ameliorates cognitive deficits in morphine dependent rats: the role of hippocampal brain-derived neurotrophic factor

Chronic exposure to opiates impairs spatial learning and memory. Given the well-known beneficial effects of voluntary exercise on cognitive functions, we investigated whether voluntary exercise would ameliorate the cognitive deficits that are induced by morphine dependence. If an effect of exercise was observed, we aimed to investigate the possible role of hippocampal brain-derived neurotrophic factor (BDNF) in the exercise-induced enhancement of learning and memory in morphine-dependent rats. The rats were injected with bi-daily doses (10mg/kg, at 12h intervals) of morphine over a period of 10 days of voluntary exercise. Following these injections, a water maze task was performed twice a day for five consecutive days, followed by a probe trial 2 days later. A specific BDNF inhibitor (TrkB-IgG chimera) was used to block the hippocampal BDNF action during the 10 days of voluntary exercise. We found that voluntary exercise blocked the ability of chronic morphine to impair spatial memory retention. A blockade of the BDNF action blunted the exercise-induced improvement of spatial memory in the dependent rats. Moreover, the voluntary exercise diminished the severity of the rats' dependency on morphine. This study demonstrates that voluntary exercise ameliorates, via a TrkB-mediated mechanism, the cognitive deficits that are induced by chronic morphine. Thus, voluntary exercise might be a potential method to ameliorate some of the deleterious behavioral consequences of the abuse of morphine and other opiates.

Alterations of brain-derived neurotrophic factor serum levels in patients with alcohol dependence

BACKGROUND

Alcohol dependence is a chronic relapsing disorder characterized by repetitive alcohol drinking patterns and a loss of control over alcohol consumption. Recent studies have hypothesized that dysregulations in brain neurotrophic support regulated by neurotrophins may be involved in the vulnerability to dependence and in the brain damage caused by chronic alcohol consumption. The neurotrophin brain-derived neurotrophic factor (BDNF) plays a pivotal role in neurodevelopment and in the maintenance of adult brain homeostasis through the regulation of neurogenesis and neuronal plasticity. The role of BDNF and its signaling in the mechanisms of alcohol dependence has been well documented in studies of animal models, but a few studies have been conducted in human peripheral tissues. On the basis of this rationale, we compared BDNF levels in both serum and plasma in alcohol-dependent patients and healthy volunteers.

METHODS

Thirty-seven patients with a principal diagnosis of alcohol dependence were recruited. In parallel, a control group of 37 unrelated volunteers matched for gender and age was enrolled. Serum and plasma BDNF levels were measured by ELISA.

RESULTS

A significant reduction in BDNF serum levels was observed in the patient group compared to healthy subjects (p = 0.028). On the contrary, no difference in BDNF plasma levels was evident between patients and controls.

CONCLUSIONS

In conclusion, our data show an alteration of BDNF peripheral content in patients with alcohol dependence, suggesting the involvement of this neurotrophin in this psychopathology.

Serum neurotrophin profile in systemic sclerosis

Background

Neurotrophins (NTs) are able to activate lymphocytes and fibroblasts; they can modulate angiogenesis and sympathic vascular function. Thus, they can be implicated in the three pathogenic processes of systemic sclerosis (SSc). The aims of this study are to determine blood levels of Nerve Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF) and Neurotrophin-3 (NT-3) in SSc and to correlate them with clinical and biological data.

Methods

Serum samples were obtained from 55 SSc patients and 32 control subjects to measure NTs levels by ELISA and to determine their relationships with SSc profiles.

Findings

Serum NGF levels were higher in SSc patients (288.26±170.34 pg/mL) than in control subjects (170.34±50.8 pg/mL, p<0.001) and correlated with gammaglobulins levels and the presence of both anti-cardiolipin and anti-Scl-70 antibodies (p<0.05). In contrast, BDNF levels were lower in SSc patients than in controls (1121.9±158.1 vs 1372.9±190.9 pg/mL, p<0.0001), especially in pulmonary arterial hypertension and diffuse SSc as compared to limited forms (all p<0.05). NT-3 levels were similar in SSc and in the control group (2657.2±2296 vs 2959.3±2555 pg/mL, NS). BDNF levels correlated negatively with increased NGF levels in the SSc group (and not in controls).

Conclusion

Low BDNF serum levels were not previously documented in SSc, particularly in the diffuse SSc subset and in patients with pulmonary hypertension or anti-Scl-70 antibodies. The negative correlation between NGF and BDNF levels observed in SSc and not in healthy controls could be implicated in sympathic vascular dysfunction in SSc.

BDNF and GDNF serum levels in alcohol-dependent patients during withdrawal

Preclinical study results suggest that brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) modulate addictive behaviour. Therefore we investigated alterations in BDNF (81 male patients) and GDNF serum levels (52 male patients) in alcohol-dependent patients during alcohol withdrawal (day 1, 7 and 14) in comparison to healthy controls (41 male controls). BDNF serum levels were not significantly altered in alcohol-dependent patients compared to healthy controls (p=0.685). GDNF serum levels were significantly reduced in the alcohol-dependent patients (p<0.001). BDNF (p=0.265) and GDNF (p=0.255) serum levels did not change significantly during alcohol withdrawal. BDNF serum levels were significantly negatively associated with alcohol withdrawal severity on day 1 (CIWA-Ar score, p=0.004). GDNF serum levels were significantly negatively associated with individual estimation of alcohol tolerance (SESA-XT score, p=0.028). There was no further association with psychometric dimensions of alcohol withdrawal. In conclusion we found that GDNF serum levels are significantly reduced in alcohol-dependent patients. GDNF serum levels were negatively associated with alcohol tolerance. Moreover BDNF serum levels were found to be associated with withdrawal severity.