Alcohol induced depressive-like behavior is associated with a reduction in hippocampal BDNF

Alcohol and substance use in older adults with treatment-resistant depression

INTRODUCTION

Alcohol and substance use are increasing in older adults, many of whom have depression, and treatment in this context may be more hazardous. We assessed alcohol and other substance use patterns in older adults with treatment-resistant depression (TRD). We examined patient characteristics associated with higher alcohol consumption and examined the moderating effect of alcohol on the association between clinical variables and falls during antidepressant treatment.

METHODS

This secondary and exploratory analysis used baseline clinical data and data on falls during treatment from a large randomized antidepressant trial in older adults with TRD (the OPTIMUM trial). Multivariable ordinal logistic regression was used to identify variables associated with higher alcohol use. An interaction model was used to evaluate the moderating effect of alcohol on falls during treatment.

RESULTS

Of 687 participants, 51% acknowledged using alcohol: 10% were hazardous drinkers (AUDIT-10 score ≥5) and 41% were low-risk drinkers (score 1-4). Benzodiazepine use was seen in 24% of all participants and in 21% of drinkers. Use of other substances (mostly cannabis) was associated with alcohol consumption: it was seen in 5%, 9%, and 15% of abstainers, low-risk drinkers, and hazardous drinkers, respectively. Unexpectedly, use of other substances predicted increased risk of falls during antidepressant treatment only in abstainers.

CONCLUSIONS

One-half of older adults with TRD in this study acknowledged using alcohol. Use of alcohol concurrent with benzodiazepine and other substances was common. Risks-such as falls-of using alcohol and other substances during antidepressant treatment needs further study.

A Rat Model of the Brain-Derived Neurotrophic Factor Val66Met Polymorphism Shows Attenuated Motivation for Alcohol Self-Administration and Diminished Propensity for Cue-Induced Relapse in Females

Brain-derived neurotrophic factor (BDNF) has been implicated in alcohol use disorder. The Val66Met polymorphism is a common variant of the BDNF gene (rs6265) which reduces activity-dependent BDNF release, and has been suggested as a risk factor for psychiatric disorders and substance use. Using an operant self-administration paradigm, this study aimed to investigate ethanol preference and ethanol seeking in a novel rat model of the BDNF Val66Met polymorphism, Val68Met rats. Male and female BDNF Val68Met rats of three genotypes (Val/Val, Val/Met and Met/Met) were trained to lever press for a 10% ethanol solution. There was no effect of Val68Met genotype on acquisition of stable response to ethanol or its extinction. Met/Met rats of both sexes had a slight, but significantly lower breakpoint during progressive ratio sessions while female rats with the Met/Met genotype demonstrated a lower propensity for reinstatement of responding to cues. There were no effects of Val68Met genotype on anxiety-like behaviour or locomotor activity. In conclusion, Met/Met rats showed lower motivation to continue to press for a reward, and also a decreased propensity to relapse, suggesting a possible protective effect of the Met/Met genotype against alcohol use disorder, at least in females.

Rutin co-treatment prevented cognitive impairment/depression-like behavior and decreased IDO activation following 35 days of ethanol administration in male Wistar rats

Alcohol (ethanol) is among the most popularly consumed beverages globally. Ethanol was earlier demonstrated to elicit cognitive impairment and depressive-like effects in both human and animal studies. Rutin (R) is known for its antioxidant, anti-inflammatory, immunomodulatory, and anti-depressive properties, among others. Herein, we investigate the impact of rutin on ethanol-induced cognitive impairment and depressive-like effects in rats and the involvement of the indoleaminergic pathway. Three groups of eight rats each were orally exposed to drinking water (group 1), ethanol (5 g/kg body weight)-group 2 (via oral gavage), and ethanol + R (5 g/kg body weight + 50 mg/kg body weight)-group 3 (via oral gavage) for 35 days. Results showed that exposure to ethanol significantly (p < 0.0001) reduced spontaneous alternation in the Y-maze and increased immobility time in the tail suspension test (TST), which indicates cognitive impairment and depressive-like behavior in rats. We observed increased IDO activity/expression, and inflammatory responses, with attendant disruption in antioxidant systems and concomitant elevation in malondialdehyde (MDA) levels in the cerebral cortex and hippocampus. Following rutin co-exposure, an ethanol-mediated increase in indoleamine 2,3-dioxygenase [IDO] activity/expression and decrease in antioxidant enzymes, in addition to an increase in markers of inflammatory response and MDA production, was significantly (p < 0.0001) prevented compared with controls. Additionally, altered behavioral indices were prevented by rutin co-exposure. Taken together, these findings reveal the involvement of the indoleaminergic pathway in rutin preventive influence against ethanol-induced cognitive impairment and depressive-like behavior in rats.

The Role of the Adenosine System on Emotional and Cognitive Disturbances Induced by Ethanol Binge Drinking in the Immature Brain and the Beneficial Effects of Caffeine

Binge drinking intake is the most common pattern of ethanol consumption by adolescents, which elicits emotional disturbances, mainly anxiety and depressive symptoms, as well as cognitive alterations. Ethanol exposure may act on the adenosine neuromodulation system by increasing adenosine levels, consequently increasing the activation of adenosine receptors in the brain. The adenosine modulation system is involved in the control of mood and memory behavior. However, there is a gap in the knowledge about the exact mechanisms related to ethanol exposure’s hazardous effects on the immature brain (i.e., during adolescence) and the role of the adenosine system thereupon. The present review attempts to provide a comprehensive picture of the role of the adenosinergic system on emotional and cognitive disturbances induced by ethanol during adolescence, exploring the potential benefits of caffeine administration in view of its action as a non-selective antagonist of adenosine receptors.

Long-term consequences of alcohol use in early adolescent mice: Focus on neuroadaptations in GR, CRF and BDNF

Our aim was to assess the cognitive and emotional state, as well as related-changes in the glucocorticoid receptor (GR), the corticotropin-releasing factor (CRF) and the brain-derived neurotrophic factor (BDNF) expression of adolescent C57BL/6J male mice after a 5-week two-bottle choice protocol (postnatal day [pd]21 to pd52). Additionally, we wanted to analyse whether the behavioural and neurobiological effects observed in late adolescence (pd62) lasted until adulthood (pd84). Behavioural testing revealed that alcohol during early adolescence increased anxiety-like and compulsive-related behaviours, which was maintained in adulthood. Concerning cognition, working memory was only altered in late adolescent mice, whereas object location test performance was impaired in both ages. In contrast, novel object recognition remained unaltered. Immunohistochemical analysis showed that alcohol during adolescence diminished BDNF+ cells in the cingulate cortex, the hippocampal CA1 layer and the central amygdala. Regarding hypothalamic-pituitary-adrenal axis (HPA) functioning, alcohol abuse increased the GR and CRF expression in the hypothalamic paraventricular nucleus and the central amygdala. Besides this, GR density was also higher in the prelimbic cortex and the basolateral amygdala, regardless of the animals' age. Our findings suggest that adolescent alcohol exposure led to long-term behavioural alterations, along with changes in BDNF, GR and CRF expression in limbic brain areas involved in stress response, emotional regulation and cognition.

Treadmill exercise sex-dependently alters susceptibility to depression-like behaviour, cytokines and BDNF in the hippocampus and prefrontal cortex of rats with sporadic Alzheimer-like disease

Alzheimer's disease (AD) is associated with increased depression-related behaviours. Previous studies have reported a greater risk of AD and depression in women. In recent years, we and others have provided evidence that exercise during life could be used as a therapeutic strategy for stress-related disorders such as depression. The main goal of the current study was to determine whether treadmill exercise during life can reduce depression-related behaviours in male and female Wistar rats with sporadic Alzheimer-like disease (ALD). Animals were subjected to treadmill exercise eight weeks before and four weeks after ALD induction by streptozocin (STZ). We measured body weight, food intake, and depression-related symptoms in rats using five behavioural tests. We measured brain-derived-neurotrophic factor (BDNF), tumour-necrosis factor (TNF)-α, and interleukin (IL)-10 levels in the hippocampus and prefrontal cortex of animals. Our findings showed that exercise but not ALD induction decreased body weight and food intake in male and female rats. ALD induction increased depression-related symptoms and hippocampal TNF-α in male and female rats. Besides, treadmill exercise alone decreased depression-related behaviours and increased hippocampal BDNF in females but not males. We also found that treadmill exercise decreased depression-related behaviours and TNF-α in the hippocampus and prefrontal cortex, and increased IL-10 in the prefrontal cortex and BDNF in the hippocampus of female ALD-induced rats. However, treadmill exercise only reduced anhedonia-like behaviour and hippocampal TNF-α in male ALD-induced rats. Overall, the evidence from this study suggests that treadmill exercise alters depression-related behaviours, brain BDNF and cytokines in a sex-dependant manner in rats with sporadic Alzheimer-like disease.

Associations between Mental Health, Alcohol Consumption and Drinking Motives during COVID-19 Second Lockdown in Ireland

Aims

The novel coronavirus pandemic (COVID-19) has impacted the lives of people worldwide since March 2020. Social restrictions aimed at flattening the curve may be associated with an increase in mental health problems and have raised concerns regarding their effect on alcohol consumption. The objective of this study was to characterize changes in alcohol use during lockdown in Ireland and associations with drinking motives and psychopathological symptoms.

Methods

We collected data from 713 adults (aged 18–60) during the second lockdown period (October/December 2020). By means of an online survey, participants self-reported their alcohol use before COVID and during lockdown. Motives to drink and psychopathological symptoms were also recorded.

Results

Our findings showed that 66% decreased their alcohol consumption, while 15% increased their alcohol consumption. An older age and coping motives were the strongest predictors of increased alcohol use during lockdown. Depression and hostility were the specific psychopathological dimensions associated with drinking to cope.

Conclusions

Older adults who drink to cope—mainly with depression symptomatology—are an important at-risk population, in line with predictions from alcohol self-medication frameworks. Future research is needed to incorporate strategies into the public mental health ecosystem.

Hippocampal regenerative medicine: neurogenic implications for addiction and mental disorders

Psychiatric illness is a prevalent and highly debilitating disorder, and more than 50% of the general population in both middle- and high-income countries experience at least one psychiatric disorder at some point in their lives. As we continue to learn how pervasive psychiatric episodes are in society, we must acknowledge that psychiatric disorders are not solely relegated to a small group of predisposed individuals but rather occur in significant portions of all societal groups. Several distinct brain regions have been implicated in neuropsychiatric disease. These brain regions include corticolimbic structures, which regulate executive function and decision making (e.g., the prefrontal cortex), as well as striatal subregions known to control motivated behavior under normal and stressful conditions. Importantly, the corticolimbic neural circuitry includes the hippocampus, a critical brain structure that sends projections to both the cortex and striatum to coordinate learning, memory, and mood. In this review, we will discuss past and recent discoveries of how neurobiological processes in the hippocampus and corticolimbic structures work in concert to control executive function, memory, and mood in the context of mental disorders.

A region of the brain called the hippocampus and its connections to other parts of the brain via what are called cortico-limbic structures are implicated in a variety of mental health disorders. These disorders can be accompanied by reduced hippocampal volume. Mi-Hyeon Jang, Doo-Sup Choi and colleagues at the Mayo Clinic College of Medicine and Science, Rochester, USA, review the role of hippocampal and cortico-limbic neurobiology in memory and mood in mental disorders. They focus particular attention on the role of neurogenesis, the production and growth of new nerve cells and connections. Disrupted neurogenesis in the adult hippocampus is implicated in conditions including addiction, depression, schizophrenia and related psychotic disorders. Learning more about neural regeneration in the hippocampus could yield insights into mental health conditions and open new avenues toward developing drug-based treatments.

An in vivo explorative study to observe the protective effects of Puerariae flos extract on chronic ethanol exposure and withdrawal male mice

Protective effects of Puerariae flos extract (PFE) on ethanol (EtOH) exposure have been previously verified. This study attempts to explore the protective effects of PEF on EtOH withdrawal models. Sixty male Kunming mice were involved which were randomly divided into five groups (intact control, EtOH group (35-day EtOH exposure), EtOH withdrawal group (28-day exposure + 7-day withdrawal), EtOH withdrawal group + positive control (Deanxit) group, and EtOH withdrawal group + PFE group). The changes of neuropsychological behaviors; hippocampal BDNF expression and CA1 neuronal density; and plasma corticotropin-releasing hormone (CRH), ACTH, and CORT levels were observed. It was found that depression-like behaviors reduced by EtOH exposure and increased by withdrawal under the 28-day EtOH exposure and 7-day withdrawal conditions. In addition, anxiety-like behaviors worsened by EtOH exposure and unchanged by withdrawal. Deanxit and PEF ameliorated such behaviors (vs. withdrawal group). Hippocampal BDNF expression was significantly downregulated by EtOH exposure and upregulated by withdrawal. Deanxit and PEF significantly upregulated the BDNF expression. The hippocampal CA1 neuronal density significantly decreased by EtOH exposure but unchanged by withdrawal and treatments. The plasma CRH, ACTH, and CORT levels show a significant enhancement by EtOH exposure and reduced by withdrawal. They were further reduced by Deanxit and PEF. The protective effects of PEF on EtOH chronic withdrawal mouse models were verified. The results of this study also indicated a complicated scenario of neuropsychological behaviors, hippocampal BDNF expression, and hypothalamic-pituitary-adrenal axis which are affected by the timing of EtOH exposure and withdrawal.

Effects and Potential Mechanisms of Alcohol Use Disorder on the Fate Determination of Newly Born Neurons in the Hippocampus

In the adult mammalian brain, new functional neurons are generated throughout life because of sustained proliferation and differentiation of neural stem cells (NSCs). The subventricular zone (SVZ), lining the lateral ventricle, and the subgranular zone (SGZ) in the dentate gyrus (DG) of the hippocampus are the two major neurogenic regions in the adult brain. This process is not fixed but is highly modulated by numerous intrinsic and extrinsic factors. Neurogenesis has become in the focus of interest for its involvement in repairing the damaged brain and this motivates researchers to detect controlling mechanisms of this process. Recent evidence suggests that alcohol usage can directly influence adult hippocampal neurogenesis, but its mechanisms remain a matter for debate. Thus, this review summarizes in vivo/in vitro studies on the role of alcohol in hippocampal neurogenesis during adulthood and clarifies its underlying mechanisms by highlighting neurotransmitters and their receptors.

7,8-Dihydroxyflavone Attenuates Alcohol-Related Behavior in Rat Models of Alcohol Consumption via TrkB in the Ventral Tegmental Area

Alcohol use disorder (AUD) is a ubiquitous substance use disorder in the world, of which neural mechanisms remain unclear. Alcohol consumption induces neuro-adaptations in the dopaminergic system originating from the ventral tegmental area (VTA), an important brain region for the reward function in AUD. Endogenous brain-derived neurotrophic factor (BDNF)-TrkB implicated in the development of neuroplasticity, including long-term potentiation of GABAergic synapses (LTP _GABA ). We previously found that ethanol blocks LTP _GABA in the VTA, either in vivo or in vitro. 7,8-dihydroflavone (7,8-DHF), a BDNF-mimicking small compound, was recently found to penetrate the blood-brain barrier to mimic the biological role of BDNF-TrkB. In this study, we demonstrate that repeated ethanol consumption (including intermittent and continuous ethanol exposure) results in low expression of BDNF in rat VTA. The amount of ethanol intake enhances significantly in rats with intermittent ethanol exposure after 72 h abstinence. Withdrawal signs emerge in rats with continuous ethanol exposure within 3 days after abstinence. Using behavioral tests, intraperitoneal injection of 7,8-DHF can reduce excessive ethanol consumption and preference as well as withdrawal signs in rats with repeated ethanol exposure. Interestingly, microinjection of K252a, an antagonist of TrkB, into the VTA blocks the effects of 7,8-DHF on ethanol-related behaviors. Furthermore, direct microinjection of BDNF into the VTA mimics the effect of 7,8-DHF on ethanol related behaviors. Taken together, 7,8-DHF attenuates alcohol-related behaviors in rats undergoing alcohol consumption via TrkB in the VTA. Our findings suggest BDNF-TrkB in VTA is a part of regulating signals for opposing neural adaptations in AUD, and 7,8-DHF may serve as a potential candidate for treating alcoholism.

Antidepressant effects of moxidectin, an antiparasitic drug, in a rat model of depression

Substantial data indicate that an imbalance in gut microbiome (GM), also referred to as dysbiosis, may play an important role in depression. Moreover, drugs that normalize GM can result in an antidepressant-like effect. It was reported recently that moxidectin (MOX), an antiparasitic drug commonly used in veterinary medicine, has a positive influence on microbiota implicated in mood regulation. We undertook this study to determine whether MOX would actually show antidepressant-like properties in an animal model of depression and whether it would affect the hippocampal and frontal cortex levels of brain-derived neurotrophic factor (BDNF) or tumor necrosis factor (TNF)-alpha, peptides that have been implicated in pathogenesis of depression and effectiveness of various antidepressants. Adult male Wistar-Kyoto rats, a putative animal model of depression, were treated with a single dose of MOX (2.5 mg/kg, i.p.) and their performance in the open field locomotor activity (OFLA) as well as in the forced swim test (FST) was evaluated at 24 h, one week and two weeks after the single injection. A separate group of rats were injected with 2.5 mg/kg MOX and sacrificed 24 h later for neurochemical evaluations. MOX resulted in a decrease in immobility score after 24 h, whereas OFLA was not affected. Concomitant with the 24 h behavioral effects, the levels of hippocampal and frontal cortical BDNF were significantly increased, whereas the levels of TNF-alpha in both these areas were significantly decreased. The decrease in immobility scores was still evident after one week, but not 2 weeks of rest. These results indicate long lasting antidepressant effects of a single MOX dose and suggest potential utility of this drug in treatment-resistant depression.

Antidepressant effects of C-Terminal domain of the heavy chain of tetanus toxin in a rat model of depression

The C-terminal domain of the heavy chain of tetanus toxin (Hc-TeTx) may be of therapeutic potential in motor impairments associated with Parkinson disease (PD). Since depression is a common co-morbid condition with PD, we undertook this study to determine whether Hc-TeTx might also show antidepressant-like properties and whether central brain-derived neurotrophic factor (BDNF) and/or tumor necrosis factor (TNF)-alpha are also affected by it. Adult male Wistar-Kyoto rats, a putative animal model of depression, were treated with various doses of Hc-TeTx (0, 20, 40 and 60 μg/kg, IM) and their performance in the open field locomotor activity (OFLA) as well as in the forced swim test (FST) was evaluated at 24 h, one week and two weeks after the single injection. A separate group of rats were injected with 60 μg/kg Hc-TeTx and sacrificed 24 h later for neurochemical evaluations. Hc-TeTx resulted in a dose-dependent decrease in immobility score after 24 h, whereas OFLA was not affected. Concomitant with the 24 h behavioral effects, the levels of hippocampal and frontal cortical BDNF were significantly increased, whereas the levels of TNF-alpha in both these areas were significantly decreased. The decrease in immobility scores following higher doses of Hc-TeTx were still evident after one week, but not 2 weeks of rest. These results indicate long lasting antidepressant effects of a single Hc-TeTx dose and suggest potential utility of Hc-TeTx in PD-depression co-morbidity.

The histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) alleviates depression-like behavior and normalizes epigenetic changes in the hippocampus during ethanol withdrawal

Withdrawal from chronic alcohol drinking can cause depression, leading to an inability to function in daily life and an increased risk for relapse to harmful drinking. Understanding the causes of alcohol withdrawal-related depression may lead to new therapeutic targets for treatment. Epigenetic factors have recently emerged as important contributors to both depression and alcohol use disorder (AUD). Specifically, acetylation of the N-terminal tails of histone proteins that package DNA into nucleosomes is altered in stress-induced models of depression and during alcohol withdrawal. The goal of this study was to examine depression-like behavior during alcohol withdrawal and associated changes in histone acetylation and expression of histone deacetylase 2 (HDAC2) in the hippocampus, a brain region critical for mood regulation and depression. Male Sprague-Dawley rats were treated with the Lieber-DeCarli ethanol liquid diet for 15 days and then underwent withdrawal. Rats were treated with the HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA), during withdrawal and were tested for depression-like behavior. In a separate group of rats, the hippocampus was analyzed for mRNA and protein expression of HDAC2 and levels of histone H3 lysine 9 acetylation (H3K9ac) during chronic ethanol exposure and withdrawal. Rats undergoing ethanol withdrawal exhibited depression-like behavior and had increased HDAC2 and decreased H3K9ac levels in specific structures of the hippocampus. Treatment with SAHA during withdrawal ameliorated depression-like behavior and normalized changes in hippocampal HDAC2 and H3K9ac levels. These results demonstrate that ethanol withdrawal causes an altered epigenetic state in the hippocampus. Treatment with an HDAC inhibitor can correct this state and alleviate depression-like symptoms developed during withdrawal. Targeting histone acetylation may be a novel strategy to reduce ethanol withdrawal-induced depression.

Enhanced Alcohol Preference and Anxiolytic Alcohol Effects in Niemann-Pick Disease Model in Mice

Major depression and alcohol use disorder are severe psychiatric diseases affecting the world's population with high comorbidity level. However, the pathogenesis of this comorbidity remains unclear, and no selective treatment for this condition is available. A pathogenic pathway and a possible therapeutic target for the treatment of depression-alcoholism comorbidity based on the hyperfunction of acid sphingomyelinase (Asm) were recently suggested. Here we analyzed the effects of alcohol on the depression/anxiety state of homozygous Asm-knockout mice (Asm − /−), which can be considered as a model of an early stage of Niemann-Pick disease, as well as their drinking pattern under normal and stress conditions. It was observed that forced treatment with alcohol (2 g/kg, i.p.) reduces the anxiety level of Asm−/− mice as measured in the elevated plus maze (EPM) test, but enhances the depression level in the forced swim test (FST). The analysis of drinking pattern of these animals in a free-choice alcohol drinking paradigm revealed higher alcohol intake and preference in Asm−/− mice compared to wild type (wt) littermates. However, this difference was overwritten by the stress exposure. Stronger sedating effects of alcohol were observed in Asm−/− mice compared to wt animals in the loss of righting reflex test after single and repeated alcohol injections (3 g/kg, i.p.). Altogether, the present findings might indicate an Asm involvement in the mechanisms of comorbidity between alcoholism and anxiety/depression.

Bupropion, a possible antidepressant without negative effects on alcohol relapse

RATIONALE

the role that antidepressants play on alcohol consumption is not well understood. Previous studies have reported that treatment with a Selective Serotonin Reuptake Inhibitor (SSRIs) increases alcohol consumption in an animal model of relapse, however it is unknown whether this effect holds for other antidepressants such as the atypical dopamine/norepinephrine reuptake inhibitors (SNDRI).

OBJECTIVES

the main goal of the present study was to compare the effects of two classes of antidepressants drugs, bupropion (SNDRI) and fluoxetine (SSRI), on alcohol consumption during relapse. Since glutamatergic and endocannabinoid signaling systems plays an important role in alcohol abuse and relapse, we also evaluated the effects of both antidepressants onthe expression of the main important genes and proteins of both systems in the prefrontal cortex, a critical brain region in alcohol relapse.

METHODS

rats were trained to self-administered alcohol. During abstinence, rats received a 14d-treatment with vehicle, fluoxetine (10 mg/kg) or bupropion (20 mg/kg), and we evaluated alcohol consumption during relapse for 3 weeks. Samples of prefrontal cortex were taken to evaluate the mRNA and protein expression of the different components of glutamatergic and endocannabinoid signaling systems.

RESULTS

fluoxetine treatment induced a long-lasting increase in alcohol consumption during relapse, an effect that was not observed in the case of bupropion treatment. The observed increases in alcohol consumption were accompanied by distinct alterations in the glutamate and endocannabinoid systems.

CONCLUSIONS

our results suggest that SSRIs can negatively impact alcohol consumption in relapse while SNDRIs have no effects. The observed increase in alcohol consumption are accompanied by functional alterations in the glutamatergic and endocannabinoid systems. This finding could open new strategies for the treatment of depression in patients with alcohol use disorders.

Brain Regional and Temporal Changes in BDNF mRNA and microRNA-206 Expression in Mice Exposed to Repeated Cycles of Chronic Intermittent Ethanol and Forced Swim Stress

Brain-derived neurotrophic factor (BDNF) expression and signaling activity in brain are influenced by chronic ethanol and stress. We previously demonstrated reduced Bdnf mRNA levels in the medial prefrontal cortex (mPFC) following chronic ethanol treatment and forced swim stress (FSS) enhanced escalated drinking associated with chronic ethanol exposure. The present study examined the effects of chronic ethanol and FSS exposure, alone and in combination, on Bdnf mRNA expression in different brain regions, including mPFC, central amygdala (CeA), and hippocampus (HPC). Additionally, since microRNA-206 has been shown to negatively regulate BDNF expression, the effects of chronic ethanol and FSS on its expression in the target brain regions were examined. Mice received four weekly cycles of chronic intermittent ethanol (CIE) vapor or air exposure and then starting 72-h later, the mice received either a single or 5 daily 10-min FSS sessions (or left undisturbed). Brain tissue samples were collected 4-h following final FSS testing and Bdnf mRNA and miR-206 levels were determined by qPCR assay. Results indicated dynamic brain regional and time-dependent changes in Bdnf mRNA and miR-206 expression. In general, CIE and FSS exposure reduced Bdnf mRNA expression while miR-206 levels were increased in the mPFC, CeA, and HPC. Further, in many instances, these effects were more robust in mice that experienced both CIE and FSS treatments. These results have important implications for the potential link between BDNF signaling in the brain and ethanol consumption related to stress interactions with chronic ethanol experience.

Moxidectin Effects on Gut Microbiota of Wistar-Kyoto Rats: Relevance to Depressive-Like Behavior

BACKGROUND/AIMS

The prevalent comorbidity between neuropsychiatric and gastrointestinal (GI) disorders is believed to be significantly influenced by gut microbiota (GM). GM may also play a substantial role in comorbidity between substance abuse (e.g. Alcohol Use Disorder, AUD) and depression. The anti-parasitic drug Moxidectin (MOX) has been reported to reduce alcohol intake in male and female mice. This effect is purported to be centrally mediated with a significant contribution linked to purinergic, P2X4 purinergic receptors. However, MOX's effects on GM in animal models of depression is not known.

METHODS

Adult male Wistar Kyoto (WKY) rats (5/group) were injected intraperitoneally (i.p.) once daily for 7 days with MOX (2.5mg/kg), or saline as control group. On day 8, approximately 20 h after the last MOX injection, animals were sacrificed, intestinal stools were collected and stored at -80°C DNA was extracted from the samples for 16S rRNA gene-based GM analysis using 16S Metagenomics application.

RESULTS

At taxa and species level, MOX affected a number of bacteria including a 30-fold increase in Bifidobacterium cholerium, a bacterium with a strong ability to degrade carbohydrates that resist digestion in the small intestine. There was a minimum of 2-fold increase in: five probiotic species of Lactobacillus, butyrate-forming Rosburia Facies and Butyrivibro proteovlasticus. In contrast, MOX depleted 11 species, including 2 species of Ruminoccus, which are positively associated with severity of irritable bowel syndrome, and 4 species of Provettela, which are closely associated with depressive-like behavior.

CONCLUSION

Thus, MOX enhanced probiotic species, and suppressed the opportunistic pathogens. Since overall effect of MOX appears to be promoting GM associated with mood enhancement (e.g. Bifidobacterium and Lactobacillus) and suppressing GM associated with inflammation (e.g. Ruminoccus), potential antidepressant and anti-inflammatory effects of MOX in suitable animal models should be investigated.

Increasing Brain-Derived Neurotrophic Factor (BDNF) in medial prefrontal cortex selectively reduces excessive drinking in ethanol dependent mice

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) has been implicated in a number of neuropsychiatric disorders, including alcohol use disorder. Studies have shown that BDNF activity in cortical regions, such as the medial prefrontal cortex (mPFC) mediates various ethanol-related behaviors. We previously reported a significant down-regulation in Bdnf mRNA in mPFC following chronic ethanol exposure compared to control mice. The present study was conducted to extend these findings by examining whether chronic ethanol treatment reduces BDNF protein expression in mPFC and whether reversing this deficit via direct injection of BDNF or viral-mediated overexpression of BDNF in mPFC alters voluntary ethanol consumption in dependent and nondependent mice. Repeated cycles of chronic intermittent ethanol (CIE) exposure was employed to model ethanol dependence, which produces robust escalation of ethanol intake. Results indicated that CIE treatment significantly increased ethanol intake and this was accompanied by a significant decrease in BDNF protein in mPFC that lasted at least 72 h after CIE exposure. In a separate study, once dependence-related increased drinking was established, bilateral infusion of BDNF (0, 0.25, 0.50 μg) into mPFC significantly decreased ethanol intake in a dose-related manner in dependent mice but did not affect moderate drinking in nondependent mice. In a third study, viral-mediated overexpression of BDNF in mPFC prevented escalation of drinking in dependent mice but did not alter intake in nondependent mice. Collectively, these results provide evidence that adaptations in cortical (mPFC) BDNF activity resulting from chronic ethanol exposure play a role in mediating excessive ethanol drinking associated with dependence.

Associations of unhappiness with sociodemographic factors and unhealthy behaviours in Chinese adolescents

Background

Evidence on the effects of lack of physical exercise, alcohol drinking and smoking on happiness is limited and inconsistent. We examined the associations of unhappiness with sociodemographic factors and these unhealthy behaviours in Chinese adolescents. In a school-based survey in 2012-13 in Hong Kong, 45 857 secondary school students (mean age 14.8 years, 54.0% boys) reported their happiness level (not happy at all/not very happy/happy/very happy), frequency of physical exercise, alcohol drinking status, smoking status and sociodemographic factors. A main and a sensitivity analysis examined the associations of unhappiness with the study factors, treating unhappiness as a binary (combining 'not happy at all' and 'not very happy') and a four-level ordered variable, respectively. The main and the sensitivity analysis both showed that unhappiness was associated with older age, very poor families, non-intact families, more co-residing smokers, lack of physical exercise and alcohol drinking; current smokers were unhappier than never and ex-smokers; unhappiness also increased significantly with the number of unhealthy behaviours ( P for trend < 0.001). In Chinese adolescents, unhappiness levels were higher in those who had a very poor family, a non-intact family and more co-residing smokers, and in those who were physically inactive, drank alcohol and smoked.

Alcohol-Induced Increases in Inflammatory Cytokines Are Attenuated by Nicotine in Region-Selective Manner in Male Rats

BACKGROUND

Heavy use of alcohol is commonly associated with heavy smoking (nicotine intake). Although many factors, including mood effects of these two drugs may contribute to their co-use, the exact neurobiological underpinnings are far from clear. It is well known that chronic alcohol exposure induces neuroinflammation that may precipitate depressive-like behavior, which is considered an important factor in alcohol relapse. Nicotine, on the other hand, possesses anti-inflammatory and antidepressant effects.

PURPOSE

In this study, we sought to determine which proinflammatory markers may be associated with the depressogenic effects of chronic alcohol and whether nicotine pretreatment may normalize these changes.

STUDY DESIGN

For this purpose, we treated adult male Wistar rats with alcohol (1.0 g/kg, IP), nicotine (0.3 mg/kg, IP) or their combination once daily for 14 days. Two prominent proinflammatory cytokines (IL-1β and TNF-α) in two primary brain regions, namely the hippocampus and frontal cortex that are intimately involved in mood regulation, were evaluated.

RESULTS

Chronic alcohol resulted in increases in both cytokines in both regions as determined by Western blot. Nicotine completely blocked alcohol-induced effects in the hippocampus, but not in the frontal cortex. These data suggest that nicotine may mitigate the inflammatory effects of alcohol in brain-selective region. Hence, the previously observed depressogenic effects of alcohol and the antidepressant effects of nicotine may at least be partially mediated through manipulations of proinflammatory cytokines in the hippocampus.

CONCLUSION

These findings suggest possible therapeutic potential of anti-inflammatory cytokines in combating alcohol-induced depression and/or relapse.

Ginseng Extract G115 Attenuates Ethanol-Induced Depression in Mice by Increasing Brain BDNF Levels

The decrease of brain-derived neurotrophic factor (BDNF) has been reported in alcohol use disorder and major depression. The effective treatment of these comorbid diseases remains undiscovered. Nutraceutical products are therefore proposed as an alternative approach to overcome this challenge. Ginseng extract G115, the standardized extract of Panax ginseng, is a widely-used nutraceutical that is beneficial for various central nervous system disorders. This study aimed to determine the antidepressant effect of ginseng extract G115 in ethanol-treated mice models. Mice received either water, amitriptyline, or various doses of G115 (p.o.) followed by water or ethanol (i.p.) for 8 days. The antidepressant activity was evaluated using forced swimming test. BDNF levels were measured from hippocampal and prefrontal cortex tissues. The results demonstrated that the increase of immobility time in depressant mice induced by ethanol was reversed by both G115 and amitriptyline treatment. A significant increase of BDNF levels in the hippocampus and prefrontal cortex was observed in ethanol-treated mice receiving G115. Taken together, this study provides scientific information on the use of G115 as an antidepressant that could be further used as a dietary supplement in comorbid alcohol use and major depressive disorders.

Lobeline attenuates ethanol abstinence-induced depression-like behavior in mice

Evidence indicates that the brain nicotinic acetylcholine receptor (nAChRs) ligand lobeline reduces depression-like behaviors, ethanol drinking, and nicotine withdrawal-induced depression-like behaviors. The purpose of the present study was to determine the effects of lobeline on ethanol abstinence-induced depression-like behavior and associated neuroadaptive changes in mice. Adult C57BL/6J male mice were allowed to drink 10% ethanol for 4 weeks using a two-bottle choice procedure. Mice were tested after 24 h and 14 days of ethanol abstinence in a forced swim test (FST), a measure for depression-like behavior. Acute lobeline treatment (1 mg/kg) significantly reduced immobility time compared to controls after 24 h and 14 days of abstinence. In addition, abstinence from chronic ethanol exposure reduced serotonin levels in the hippocampus, which was reversed by acute lobeline treatment. Repeated lobeline treatment (1 mg/kg, once daily) for 14 days during ethanol abstinence also significantly reduced FST immobility in mice exposed to ethanol. Chronic ethanol exposure significantly reduced the number of 5-bromo 2'-deoxyuridine (BrdU)-positive cells in the dentate gyrus of the hippocampus, indicating decreased hippocampal cell proliferation. Abstinence from chronic ethanol exposure also decreased brain-derived neurotrophic factor (BDNF) in the dentate gyrus and CA3 region of the hippocampus. In contrast, repeated lobeline treatment significantly increased both BrdU- and BDNF-positive cells. Taken together, our results indicate that lobeline produced antidepressant-like effects, likely by targeting brain β2-containing nAChRs, serotonergic neurotransmission, and/or hippocampal cell proliferation. Therefore, lobeline may have therapeutic utility to treat alcohol abstinence-induced depression.

A role for histone acetylation mechanisms in adolescent alcohol exposure-induced deficits in hippocampal brain-derived neurotrophic factor expression and neurogenesis markers in adulthood

Binge drinking during adolescence is a risk factor for neuropsychiatric disorders that can develop later in life. Histone acetylation is an important epigenetic mechanism that contributes to neurodevelopment. We investigated the effects of adolescent intermittent ethanol (AIE) exposure, as opposed to normal saline (AIS) exposure, on histone acetylation-mediated regulation of brain-derived neurotrophic factor (BDNF) expression and developmental stages of neurogenesis (proliferating and immature neurons) in the hippocampus in adulthood. AIE exposure increased whole hippocampal histone deacetylase (HDAC) activity and decreased binding protein of cyclic adenosine monophosphate response element binding protein (CBP) and histone H3-K9 acetylation levels in the CA1, CA2, and CA3 regions of the hippocampus. BDNF protein and exon IV mRNA levels in the CA1 and CA3 regions of the hippocampus of AIE-exposed adult rats were decreased as compared to AIS-exposed adult rats. AIE-induced anxiety-like behaviors and deficits in histone H3 acetylation at BDNF exon IV promoter in the hippocampus during adulthood, which were reversed by treatment with the HDAC inhibitor, trichostatin A (TSA). Similarly, neurogenesis was inhibited by AIE in adulthood as demonstrated by the decrease in Ki-67 and doublecortin (DCX)-positive cells in the dentate gyrus, which was normalized by TSA treatment. These results indicate that AIE exposure increases HDACs and decreases CBP levels that may be associated with a decrease in histone H3 acetylation in the hippocampus. These epigenetic changes potentially decrease BDNF expression and inhibit neurogenesis in the hippocampus that may be involved in AIE-induced behavioral abnormalities, including anxiety, in adulthood.

Adolescent Alcohol Exposure Persistently Impacts Adult Neurobiology and Behavior

Adolescence is a developmental period when physical and cognitive abilities are optimized, when social skills are consolidated, and when sexuality, adolescent behaviors, and frontal cortical functions mature to adult levels. Adolescents also have unique responses to alcohol compared with adults, being less sensitive to ethanol sedative-motor responses that most likely contribute to binge drinking and blackouts. Population studies find that an early age of drinking onset correlates with increased lifetime risks for the development of alcohol dependence, violence, and injuries. Brain synapses, myelination, and neural circuits mature in adolescence to adult levels in parallel with increased reflection on the consequence of actions and reduced impulsivity and thrill seeking. Alcohol binge drinking could alter human development, but variations in genetics, peer groups, family structure, early life experiences, and the emergence of psychopathology in humans confound studies. As adolescence is common to mammalian species, preclinical models of binge drinking provide insight into the direct impact of alcohol on adolescent development. This review relates human findings to basic science studies, particularly the preclinical studies of the Neurobiology of Adolescent Drinking in Adulthood (NADIA) Consortium. These studies focus on persistent adult changes in neurobiology and behavior following adolescent intermittent ethanol (AIE), a model of underage drinking. NADIA studies and others find that AIE results in the following: increases in adult alcohol drinking, disinhibition, and social anxiety; altered adult synapses, cognition, and sleep; reduced adult neurogenesis, cholinergic, and serotonergic neurons; and increased neuroimmune gene expression and epigenetic modifiers of gene expression. Many of these effects are specific to adolescents and not found in parallel adult studies. AIE can cause a persistence of adolescent-like synaptic physiology, behavior, and sensitivity to alcohol into adulthood. Together, these findings support the hypothesis that adolescent binge drinking leads to long-lasting changes in the adult brain that increase risks of adult psychopathology, particularly for alcohol dependence.

Duality of Antidepressants and Neuroprotectants

The co-morbidity of neuropsychiatric disorders, particularly major depressive disorder (MDD) with neurodegenerative diseases, in particular Parkinson's disease (PD) is now well recognized. Indeed, it is suggested that depressive disorders, especially in late life, may be an indication of latent neurodegeneration. Thus, it is not unreasonable to expect that deterrents of MDD may also deter the onset and/or progression of the neurodegenerative diseases including PD. In this review, examples of neuroprotective efficacy of established as well as prospective antidepressants are provided. Conversely, mood-regulating effects of some neuroprotective drugs are also presented. Thus, in addition to currently used antidepressants, ketamine, nicotine, curcumin, and resveratrol are discussed for their dual efficacy. In addition, potential neurobiological substrates for their actions are presented. It is concluded that pharmacological developments of mood-regulating or neuroprotective drugs can have cross benefit in co-morbid conditions of neuropsychiatric and neurodegenerative disorders and that inflammatory and neurotrophic factors play important roles in both conditions.

Effects of Ethanol on the Expression Level of Various BDNF mRNA Isoforms and Their Encoded Protein in the Hippocampus of Adult and Embryonic Rats

We aimed to compare the effects of oral ethanol (Eth) alone or combined with the phytoestrogen resveratrol (Rsv) on the expression of various brain-derived neurotrophic factor (BDNF) transcripts and the encoded protein pro-BDNF in the hippocampus of pregnant and embryonic rats. A low (0.25 g/kg body weight (BW)/day) dose of Eth produced an increase in the expression of BDNF exons I, III and IV and a decrease in that of the exon IX in embryos, but failed to affect BDNF transcript and pro-BDNF protein expression in adults. However, co-administration of Eth 0.25 g/kg·BW/day and Rsv led to increased expression of BDNF exons I, III and IV and to a small but significant increase in the level of pro-BDNF protein in maternal rats. A high (2.5 g/kg·BW/day) dose of Eth increased the expression of BDNF exons III and IV in embryos, but it decreased the expression of exon IX containing BDNF mRNAs in the maternal rats. While the high dose of Eth alone reduced the level of pro-BDNF in adults, it failed to change the levels of pro-BDNF in embryos. Eth differentially affects the expression pattern of BDNF transcripts and levels of pro-BDNF in the hippocampus of both adult and embryonic rats.

Recent Advances in Nicotinic Receptor Signaling in Alcohol Abuse and Alcoholism

Alcohol is the most commonly abused legal substance and alcoholism is a serious public health problem. It is a leading cause of preventable death in the world. The cellular and molecular mechanisms of alcohol reward and addiction are still not well understood. Emerging evidence indicates that unlike other drugs of abuse, such as nicotine, cocaine, or opioids, alcohol targets numerous channel proteins, receptor molecules, and signaling pathways in the brain. Previously, research has identified brain nicotinic acetylcholine receptors (nAChRs), a heterogeneous family of pentameric ligand-gated cation channels expressed in the mammalian brain, as critical molecular targets for alcohol abuse and dependence. Genetic variations encoding nAChR subunits have been shown to increase the vulnerability to develop alcohol dependence. Here, we review recent insights into the rewarding effects of alcohol, as they pertain to different nAChR subtypes, associated signaling molecules, and pathways that contribute to the molecular mechanisms of alcoholism and/or comorbid brain disorders. Understanding these cellular changes and molecular underpinnings may be useful for the advancement of brain nicotinic-cholinergic mechanisms, and will lead to a better translational and therapeutic outcome for alcoholism and/or comorbid conditions.

Behavioral and molecular responses to electroconvulsive shock differ between genetic and environmental rat models of depression

Depression׳s causes play a role in individuals׳ different responses to antidepressant treatments, which require advancements. We investigated the mechanisms behind and responses to a highly effective antidepressant treatment, electroconvulsive therapy (ECT), in rat models with different (genetic or environmental) depression causes. Wistar Kyoto (WKY) rats and Wistar rats treated with chronic unpredictable mild stresses (CUMS) were used as genetic and environmental rat models of depression, respectively. The rats underwent electroconvulsive shock (ECS, the animal analog of ECT) or sham ECS. We performed a sucrose preference test, open field test, and Morris water maze to assess behavior. Hippocampal neuron numbers were measured with Nissl stain. Hippocampal BDNF, CREB, and p-CREB proteins were assayed with ELISA or western blotting. The main results showed that ECS impaired WKY rats׳ memories but improved CUMS rats׳ memories. It elevated hippocampal BDNF and CREB proteins only in CUMS rats, while it improved depressive behavior and hippocampal p-CREB protein levels in both rats, with more effective regulations in the CUMS rats. ECS did not change the hippocampal neuron number in both rats. These findings suggest that ECS exerted up-regulating effects on hippocampal BDNF and CREB (and its phosphorylation) in depressed rats, and the environmental model responded better.

Ethanol-induced epigenetic regulations at the Bdnf gene in C57BL/6J mice

High ethanol intake is well known to induce both anxiolytic and anxiogenic effects, in correlation with chromatin remodeling in the amygdaloid brain region and deficits in cell proliferation and survival in the hippocampus of rodents. Whether only moderate but chronic ethanol intake in C57BL/6J mice could also have an impact on chromatin remodeling and neuroplasticity was addressed here. Chronic ethanol consumption in a free choice paradigm was found to induce marked changes in the expression of genes implicated in neural development and histone post-translational modifications in the mouse hippocampus. Transcripts encoding neural bHLH activators and those from Bdnf exons II, III and VI were upregulated, whereas those from Bdnf exon VIII and Hdacs were downregulated by ethanol compared with water consumption. These ethanol-induced changes were associated with enrichment in both acetylated H3 at Bdnf promoter PVI and trimethylated H3 at PII and PIII. Conversely, acetylated H3 at PIII and PVIII and trimethylated H3 at PVIII were decreased in ethanol-exposed mice. In parallel, hippocampal brain-derived neurotrophic factor (BDNF) levels and TrkB-mediated neurogenesis in the dentate gyrus were significantly enhanced by ethanol consumption. These results suggest that, in C57BL/6J mice, chronic and moderate ethanol intake produces marked epigenetic changes underlying BDNF overexpression and downstream hippocampal neurogenesis.

Brain-derived neurotrophic factor and addiction: Pathological versus therapeutic effects on drug seeking

Many abused drugs lead to changes in endogenous brain-derived neurotrophic factor (BDNF) expression in neural circuits responsible for addictive behaviors. BDNF is a known molecular mediator of memory consolidation processes, evident at both behavioral and neurophysiological levels. Specific neural circuits are responsible for storing and executing drug-procuring motor programs, whereas other neural circuits are responsible for the active suppression of these "seeking" systems. These seeking-circuits are established as associations are formed between drug-associated cues and the conditioned responses they elicit. Such conditioned responses (e.g. drug seeking) can be diminished either through a passive weakening of seeking- circuits or an active suppression of those circuits through extinction. Extinction learning occurs when the association between cues and drug are violated, for example, by cue exposure without the drug present. Cue exposure therapy has been proposed as a therapeutic avenue for the treatment of addictions. Here we explore the role of BDNF in extinction circuits, compared to seeking-circuits that "incubate" over prolonged withdrawal periods. We begin by discussing the role of BDNF in extinction memory for fear and cocaine-seeking behaviors, where extinction circuits overlap in infralimbic prefrontal cortex (PFC). We highlight the ability of estrogen to promote BDNF-like effects in hippocampal-prefrontal circuits and consider the role of sex differences in extinction and incubation of drug-seeking behaviors. Finally, we examine how opiates and alcohol "break the mold" in terms of BDNF function in extinction circuits.

Alcohol and adult hippocampal neurogenesis: promiscuous drug, wanton effects

Adult neurogenesis is now widely accepted as an important contributor to hippocampal integrity and function but also dysfunction when adult neurogenesis is affected in neuropsychiatric diseases such as alcohol use disorders. Excessive alcohol consumption, the defining characteristic of alcohol use disorders, results in a variety of cognitive and behavioral impairments related wholly or in part to hippocampal structure and function. Recent preclinical work has shown that adult neurogenesis may be one route by which alcohol produces hippocampal neuropathology. Alcohol is a pharmacologically promiscuous drug capable of interfering with adult neurogenesis through multiple mechanisms. This review will discuss the primary mechanisms underlying alcohol-induced changes in adult hippocampal neurogenesis including alcohol's effects on neurotransmitters, CREB and its downstream effectors, and the neurogenic niche.

P2X4 receptor regulates alcohol-induced responses in microglia

Mounting evidence indicates that alcohol-induced neuropathology may result from multicellular responses in which microglia cells play a prominent role. Purinergic receptor signaling plays a key role in regulating microglial function and, more importantly, mediates alcohol-induced effects. Our findings demonstrate that alcohol increases expression of P2X4 receptor (P2X4R), which alters the function of microglia, including calcium mobilization, migration and phagocytosis. Our results show a significant up-regulation of P2X4 gene expression as analyzed by real-time qPCR (***p < 0.002) and protein expression as analyzed by flow cytometry (**p < 0.004) in embryonic stem cell-derived microglial cells (ESdM) after 48 hours of alcohol treatment, as compared to untreated controls. Calcium mobilization in ethanol treated ESdM cells was found to be P2X4R dependent using 5-BDBD, a P2X4R selective antagonist. Alcohol decreased migration of microglia towards fractalkine (CX3CL1) by 75 % following 48 h of treatment compared to control (***p < 0.001). CX3CL1-dependent migration was confirmed to be P2X4 receptor-dependent using the antagonist 5-BDBD, which reversed the effects as compared to alcohol alone (***p < 0.001). Similarly, 48 h of alcohol treatment significantly decreased phagocytosis of microglia by 15 % compared to control (*p < 0.05). 5-BDBD pre-treatment prior to alcohol treatment significantly increased microglial phagocytosis (***p < 0.001). Blocking P2X4R signaling with 5-BDBD decreased the level of calcium mobilization compared to ethanol treatment alone. These findings demonstrate that P2X4 receptor may play a role in modulating microglial function in the context of alcohol abuse.

Innate BDNF expression is associated with ethanol intake in alcohol-preferring AA and alcohol-avoiding ANA rats

We have shown recently that acute administration of ethanol modulates the expression of brain-derived neurotrophic factor (BDNF) in several rat brain areas known to be involved in the development of addiction to ethanol and other drugs of abuse, suggesting that BDNF may be a factor contributing to the neuroadaptive changes set in motion by ethanol exposure. The purpose of the present study was to further clarify the role of BDNF in reinforcement from ethanol and in the development of addiction to ethanol by specifying the effect of acute administration of ethanol (1.5 or 3.0 g/kg i.p.) on the expression profile of BDNF mRNA in the ventral tegmental area and in the terminal areas of the mesolimbic dopamine pathway in the brain of alcohol-preferring AA and alcohol-avoiding ANA rats, selected for high and low voluntary ethanol intake, respectively. The level of BDNF mRNA expression was higher in the amygdala and ventral tegmental area of AA than in those of ANA rats, and there was a trend for a higher level in the nucleus accumbens. In the amygdala and hippocampus, a biphasic change in the BDNF mRNA levels was detected: the levels were decreased at 3 and 6h but increased above the basal levels at 24h. Furthermore, there was a difference between the AA and ANA lines in the effect of ethanol, the ANA rats showing an increase in BDNF mRNA levels while such a change was not seen in AA rats. These findings suggest that the innate levels of BDNF expression may play a role in the mediation of the reinforcing effects of ethanol and in the control of ethanol intake.

Effect of peripheral opioid receptor agonists on depressive activity of ethanol

We studied the effect of peripheral μ- and κ-opioid receptor agonists (not crossing the bloodbrain barrier) on locomotor activity and metabolism in rats after acute administration of ethanol. Intraperitoneal injection of ethanol in a single dose of 2 g/kg had a strong depressive effect manifested in a decrease in horizontal locomotor activity and suppression of metabolism. μ-Opioid receptor agonist DAMGO and κ-opioid receptor agonist ICI 204,448 partly abolished the effect of ethanol on locomotor activity of rats. ICI 204,448 was most potent in this respect. In contrast to μ-opioid receptor agonist DAMGO, κ-opioid receptor agonist ICI 204,448 prevented metabolism suppression induced by ethanol. Our results indicate that ICI 204,448 significantly inhibits the depressive effect of ethanol. DAMGO showed only partial effectiveness under these experimental conditions.

Antidepressant effects of resveratrol in an animal model of depression

Resveratrol (3,4',5-trihydroxy-trans-stilbene) is a natural non-flavonoid polyphenol antioxidant extracted from red grapes in the processing of wine. Initially it was studied for its potential as anticancer drug, and later was found to reduce cardiovascular disease. More recently resveratrol was shown to alleviate depressive-like symptoms induced by stress or other means in mice and rats. The major purpose of this study was to investigate whether resveratrol would manifest an antidepressant effect in Wistar-Kyoto (WKY) rats, a putative and non-induced animal model of depression, and whether this effect might be associated with an increase in hippocampal and frontal cortical brain-derived neurotrophic factor (BDNF), a protein implicated in chronic effects of many antidepressants. Adult male WKY rats were injected with two doses of resveratrol (10 and 40 mg/kg, i.p.) and their behavior in the open field locomotor activity (LMA), forced swim test (FST: a measure of helplessness), and sucrose preference test (SPT: a measure of anhedonia) was evaluated after a single acute injection or following 7 days of daily treatment. Both acute and chronic administration of resveratrol resulted in a dose-dependent decrease in FST. However, only chronic resveratrol resulted in dose-dependent increase in sucrose consumption. LMA was not affected by any treatment. Parallel to the observed behavioral effects the level of hippocampal, but not frontal cortical, BDNF was also dose-dependently elevated after chronic resveratrol administration. These findings indicate an antidepressant-like effect of resveratrol in an animal model of depression possibly via activation of hippocampal BDNF, and suggest therapeutic potential of resveratrol in at least a subpopulation of depressed patients.

Microarray profiling and co-expression network analysis of circulating lncRNAs and mRNAs associated with major depressive disorder

LncRNAs, which represent one of the most highly expressed classes of ncRNAs in the brain, are becoming increasingly interesting with regard to brain functions and disorders. However, changes in the expression of regulatory lncRNAs in Major Depressive Disorder (MDD) have not yet been reported. Using microarrays, we profiled the expression of 34834 lncRNAs and 39224 mRNAs in peripheral blood sampled from MDD patients as well as demographically-matched controls. Among these, we found that 2007 lncRNAs and 1667 mRNAs were differentially expressed, 17 of which were documented as depression-related gene in previous studies. Gene Ontology (GO) and pathway analyses indicated that the biological functions of differentially expressed mRNAs were related to fundamental metabolic processes and neurodevelopment diseases. To investigate the potential regulatory roles of the differentially expressed lncRNAs on the mRNAs, we also constructed co-expression networks composed of the lncRNAs and mRNAs, which shows significant correlated patterns of expression. In the MDD-derived network, there were a greater number of nodes and connections than that in the control-derived network. The lncRNAs located at chr10:874695-874794, chr10:75873456-75873642, and chr3:47048304-47048512 may be important factors regulating the expression of mRNAs as they have previously been reported associations with MDD. This study is the first to explore genome-wide lncRNA expression and co-expression with mRNA patterns in MDD using microarray technology. We identified circulating lncRNAs that are aberrantly expressed in MDD and the results suggest that lncRNAs may contribute to the molecular pathogenesis of MDD.

Chronic binge-like alcohol consumption in adolescence causes depression-like symptoms possibly mediated by the effects of BDNF on neurogenesis

Here we investigated whether changes in neurogenesis and brain-derived neurotrophic factor (BDNF) expression are possible mechanisms involved in the depression-like symptom during the withdrawal/abstinence period after chronic binge-pattern alcohol consumption given the limited number of studies addressing the link between these factors in the adolescent brain. Forty-seven male Sprague-Dawley rats were used in the study and the experimental protocol started when rats were 25-days old. Rats were assigned to either: (a) ethanol or (b) control group. Animals in each group were further randomized to receive either: BDNF receptor agonist or vehicle. Rats were trained to self-administer ethanol and the binge protocol consisted of daily 30-min experimental sessions 4h into the dark period for 12days. Two days after the last drinking session, rats were tested in the sucrose preference test to evaluate anhedonia and the open field test after habituation to evaluate behavioral despair. Our data showed that: (1) self-administration of alcohol in a binge-like pattern causes inebriation as defined by the National Institute on Alcohol Abuse and Alcoholism and this pattern of alcohol exposure is associated with the development of a depression-like symptom; (2) no significant difference in blood alcohol levels between the two ethanol groups; and (3) chronic binge drinking resulted in the development of a depressive phenotype, decreased survival and neuronal differentiation of neural progenitor cells in the hippocampus, and decreased BDNF effect during the withdrawal period. But the most important finding in our study is that augmenting BDNF actions through the use of tyrosine kinase B (TrkB, a BDNF receptor) agonist restored neurogenesis and abolished the alcohol-induced anhedonia and despair behaviors seen during the withdrawal/abstinence period. Our results suggest that BDNF might be a molecule that can be targeted for interventions in alcoholism-depression co-incidence.