Neuroepigenetics of Neurotrophin Signaling: Neurobiology of Anxiety and Affective Disorders

Enhanced neuronal activity by suffruticosol A extracted from Paeonia lactiflora via partly BDNF signaling in scopolamine-induced memory-impaired mice

Neurodegenerative diseases are explained by progressive defects of cognitive function and memory. These defects of cognition and memory dysfunction can be induced by the loss of brain-derived neurotrophic factors (BDNF) signaling. Paeonia lactiflora is a traditionally used medicinal herb in Asian countries and some beneficial effects have been reported, including anti-oxidative, anti-inflammatory, anti-cancer activity, and potential neuroprotective effects recently. In this study, we found that suffruticosol A is a major compound in seeds of Paeonia lactiflora. When treated in a SH-SY5 cell line for measuring cell viability and cell survival, suffruticosol A increased cell viability (at 20 µM) and recovered scopolamine-induced neurodegenerative characteristics in the cells. To further confirm its neural amelioration effects in the animals, suffruticosol A (4 or 15 ng, twice a week) was administered into the third ventricle beside the brain of C57BL/6 mice for one month then the scopolamine was intraperitoneally injected into these mice to induce impairments of cognition and memory before conducting behavioral experiments. Central administration of suffruticosol A into the brain restored the memory and cognition behaviors in mice that received the scopolamine. Consistently, the central treatments of suffruticosol A showed rescued cholinergic deficits and BDNF signaling in the hippocampus of mice. Finally, we measured the long-term potentiation (LTP) in the hippocampal CA3-CA1 synapse to figure out the restoration of the synaptic mechanism of learning and memory. Bath application of suffruticosol A (40 µM) improved LTP impairment induced by scopolamine in hippocampal slices. In conclusion, the central administration of suffruticosol A ameliorated neuronal effects partly through elevated BDNF signaling.

Hippocampal and amygdalar increased BDNF expression in the extinction of opioid-induced place preference

The opioid crisis was exacerbated during the COVID-19 pandemic in the United States with alarming statistics about overdose-related deaths. Current treatment options, such as medication assisted treatments, have been unable to prevent relapse in many patients, whereas cue-based exposure therapy have had mixed results in human trials. To improve patient outcomes, it is imperative to develop animal models of addiction to understand molecular mechanisms and identify potential therapeutic targets. We previously found increased brain derived neurotrophic factor (bdnf) transcript in the ventral striatum/nucleus accumbens (VS/NAc) of rats that extinguished morphine-induced place preference. Here, we expand our study to determine whether BDNF protein expression was modulated in mesolimbic brain regions of the reward system in animals exposed to extinction training. Drug conditioning and extinction sessions were followed by Western blots for BDNF in the hippocampus (HPC), amygdala (AMY) and VS/NAc. Rears, as a measure of withdrawal-induced anxiety were also measured to determine their impact on extinction. Results showed that animals who received extinction training and successfully extinguished morphine CPP significantly increased BDNF in the HPC when compared to animals deprived of extinction training (sham-extinction). This increase was not significant in animals who failed to extinguish (extinction-resistant). In AMY, all extinction-trained animals showed increased BDNF, regardless of behavior phenotype. No BDNF modulation was observed in the VS/NAc. Finally, extinction-trained animals showed no difference in rears regardless of extinction outcome, suggesting that anxiety elicited by drug withdrawal did not significantly impact extinction of morphine CPP. Our results suggest that BDNF expression in brain regions of the mesolimbic reward system could play a key role in extinction of opioid-induced maladaptive behaviors and represents a potential therapeutic target for future combined pharmacological and extinction-based therapies.

Targeting Epigenetic Mechanisms to Treat Alcohol Use Disorders (AUD)

BACKGROUND

The impact of abusive alcohol consumption on human health is remarkable. According to the World Health Organization (WHO), approximately 3.3 million people die annually because of harmful alcohol consumption (the figure represents around 5.9% of global deaths). Alcohol Use Disorder (AUD) is a chronic disease where individuals exhibit compulsive alcohol drinking and present negative emotional states when they do not drink. In the most severe manifestations of AUD, the individuals lose control over intake despite a decided will to stop drinking. Given the multiple faces and the specific forms of this disease, the term AUD often appears in the plural (AUDs). Since only a few approved pharmacological treatments are available to treat AUD and they do not apply to all individuals or AUD forms, the search for compounds that may help to eliminate the burden of the disease and complement other therapeutical approaches is necessary.

METHODS

This work reviews recent research focused on the involvement of epigenetic mechanisms in the pathophysiology of AUD. Excessive drinking leads to chronic and compulsive consumption that eventually damages the organism. The central nervous system is a key target and is the focus of this study. The search for the genetic and epigenetic mechanisms behind the intricated dysregulation induced by ethanol will aid researchers in establishing new therapy approaches.

CONCLUSION

Recent findings in the field of epigenetics are essential and offer new windows for observation and research. The study of small molecules that inhibit key epienzymes involved in nucleosome architecture dynamics is necessary in order to prove their action and specificity in the laboratory and to test their effectivity and safety in clinical trials with selected patients bearing defined alterations caused by ethanol.

Central Administration of Ampelopsin A Isolated from Vitis vinifera Ameliorates Cognitive and Memory Function in a Scopolamine-Induced Dementia Model

Neurodegenerative diseases are characterized by the progressive degeneration of the function of the central nervous system or peripheral nervous system and the decline of cognition and memory abilities. The dysfunctions of the cognitive and memory battery are closely related to inhibitions of neurotrophic factor (BDNF) and brain-derived cAMP response element-binding protein (CREB) to associate with the cholinergic system and long-term potentiation. Vitis vinifera, the common grapevine, is viewed as the important dietary source of stilbenoids, particularly the widely-studied monomeric resveratrol to be used as a natural compound with wide-ranging therapeutic benefits on neurodegenerative diseases. Here we found that ampelopsin A is a major compound in V. vinifera and it has neuroprotective effects on experimental animals. Bath application of ampelopsin A (10 ng/µL) restores the long-term potentiation (LTP) impairment induced by scopolamine (100 μM) in hippocampal CA3-CA1 synapses. Based on these results, we administered the ampelopsin A (10 ng/µL, three times a week) into the third ventricle of the brain in C57BL/6 mice for a month. Chronic administration of ampelopsin A into the brain ameliorated cognitive memory-behaviors in mice given scopolamine (0.8 mg/kg, i.p.). Studies of mice’s hippocampi showed that the response of ampelopsin A was responsible for the restoration of the cholinergic deficits and molecular signal cascades via BDNF/CREB pathways. In conclusion, the central administration of ampelopsin A contributes to increasing neurocognitive and neuroprotective effects on intrinsic neuronal excitability and behaviors, partly through elevated BDNF/CREB-related signaling.

Central administration of afzelin extracted from Ribes fasciculatum improves cognitive and memory function in a mouse model of dementia

Neurodegenerative disorders are characterized by the decline of cognitive function and the progressive loss of memory. The dysfunctions of the cognitive and memory system are closely related to the decreases in brain-derived neurotrophic factor (BDNF) and cAMP response element-binding protein (CREB) signalings. Ribes fasciculatum, a medicinal plant grown in diverse countries, has been reported to pharmacological effects for autoimmune diseases and aging recently. Here we found that afzelin is a major compound in Ribes fasciculatum. To further examine its neuroprotective effect, the afzelin (100 ng/µl, three times a week) was administered into the third ventricle of the hypothalamus of C57BL/6 mice for one month and scopolamine was injected (i.p.) to these mice to impair cognition and memory before each behavior experiment. The electrophysiology to measure long-term potentiation and behavior tests for cognitive and memory functions were performed followed by investigating related molecular signaling pathways. Chronic administration of afzelin into the brain ameliorated synaptic plasticity and cognitive/memory behaviors in mice given scopolamine. Studies of mice's hippocampi revealed that the response of afzelin was accountable for the restoration of the cholinergic systems and molecular signal transduction via CREB-BDNF pathways. In conclusion, the central administration of afzelin leads to improved neurocognitive and neuroprotective effects on synaptic plasticity and behaviors partly through the increase in CREB-BDNF signaling.

Symptom cluster profiles following traumatic orthopedic injuries: A protocol

Traumatic injuries affect millions of Americans annually, resulting in $671 billion in healthcare costs and lost productivity. Postinjury symptoms, like pain, sleep disturbance, anxiety, depression, and stressor-related disorders are highly prevalent following traumatic orthopedic injuries (TOI) and may contribute to negative long-term outcomes. Symptoms rarely present in isolation, but in clusters of two or more symptoms that co-occur to affect health in aggregate. Identifying symptom cluster profiles following TOI may identify those at highest risk for negative outcomes. Dysregulation of brain-derived neurotrophic factor (BDNF) is a potential biological mechanism responsible for symptom cluster profile membership after TOI and may be targeted in future precision-health applications. The purpose of this paper is to present the protocol of a cross-sectional study designed to identify symptom cluster profiles and measure the extent to which the BDNF val66met mutation and serum concentration of BDNF are associated with membership in symptom cluster profiles. We plan to recruit 150 TOI survivors within the first 72 h of injury. The study aims are to (1) describe TOI survivors' membership in symptom cluster profiles, indicated by pain, sleep disturbance, and symptoms of anxiety, depression, and stressor-related disorders, immediately following a TOI; (2) examine associations between demographic and clinical factors and symptom cluster profile membership among TOI survivors; (3) test the hypothesis that low serum concentrations of BDNF are associated with membership among symptom cluster profiles following TOI; and (4) test the hypothesis that the presence of the val66met mutation on one or both alleles of the BDNF gene is associated with membership among symptom cluster profiles following TOI.

mRNA and miRNA profiles in the nucleus accumbens are associated with psychological stress-induced susceptible and resilient mice

BACKGROUND

Stress may be one of the main causes of fear and anxiety. Previous studies have shown that the nucleus accumbens is involved in emotional responses. However, in the nucleus accumbens, the mRNA and miRNA profiles of stress susceptibility and resilience of psychological stress still need to be studied.

MATERIALS AND METHODS

In this study, by observing the conspecific being attacked, the witness group experienced psychological stress. After five days of psychological stress, the fear memory of mice was measured by social interaction test, and the degree of anxiety was measured by elevated plus maze. mRNA and miRNA profiles in the nucleus accumbens tissue of control, susceptible and resilient mice were established by high-throughput sequencing.

RESULTS

In susceptible mice versus resilient mice, the Differentially expressed genes (DEGs) may be related to psychological stress-induced susceptibility. DEGs enriched in Cell adhesion molecules, Neuroactive ligand-receptor interaction, Gap junction, PI3K-Akt, VEGF, Jak-STAT, Ras, and Chemokine pathways were up-regulated. DEGs enriched in cGMP-PKG, B cell receptor, and NOD-like receptor pathways were down- regulated. The sequencing results of mRNAs and miRNAs were verified by qRT-PCR and dual luciferase reporter assay.

CONCLUSION

The imbalance of different synapses and pathways in the nucleus accumbens may be related to susceptibility and resilience caused by psychological stress.

Novel pharmacological targets in drug development for the treatment of anxiety and anxiety-related disorders

Current medication for anxiety disorders is suboptimal in terms of efficiency and tolerability, highlighting the need for improved drug treatments. In this review an overview of drugs being studied in different phases of clinical trials for their potential in the treatment of fear-, anxiety- and trauma-related disorders is presented. One strategy followed in drug development is refining and improving compounds interacting with existing anxiolytic drug targets, such as serotonergic and prototypical GABAergic benzodiazepines. A more innovative approach involves the search for compounds with novel mechanisms of anxiolytic action using the growing knowledge base concerning the relevant neurocircuitries and neurobiological mechanisms underlying pathological fear and anxiety. The target systems evaluated in clinical trials include glutamate, endocannabinoid and neuropeptide systems, as well as ion channels and targets derived from phytochemicals. Examples of promising novel candidates currently in clinical development for generalised anxiety disorder, social anxiety disorder, panic disorder, obsessive compulsive disorder or post-traumatic stress disorder include ketamine, riluzole, xenon with one common pharmacological action of modulation of glutamatergic neurotransmission, as well as the neurosteroid aloradine. Finally, compounds such as D-cycloserine, MDMA, L-DOPA and cannabinoids have shown efficacy in enhancing fear-extinction learning in humans. They are thus investigated in clinical trials as an augmentative strategy for speeding up and enhancing the long-term effectiveness of exposure-based psychotherapy, which could render chronic anxiolytic drug treatment dispensable for many patients. These efforts are indicative of a rekindled interest and renewed optimism in the anxiety drug discovery field, after decades of relative stagnation.

Genetic predictor of current suicidal ideation in US service members deployed to Iraq and Afghanistan

OBJECTIVE

Suicide is one of the ten leading causes of death in United States and the suicide rate in the military population has increased since the start of the Iraq and Afghanistan wars. However, few biomarkers for current suicidal ideation (CSI) have been identified. The current study examined the association of four candidate genes with CSI in active duty US Army Special Operations Command and National Guard units (n = 3,889) who served in Iraq and Afghanistan between November 2009 and July 2014.

METHODS

Current PTSD symptoms and CSI were assessed using the PTSD Checklist (PCL) and PHQ-9, respectively. Traumatic events were assessed using items from the Life Events Checklist (LEC) that met the DSM-IV PTSD criteria of a traumatic stressor. All genotypes of saliva DNA were discriminated using the TaqMan 5'-exonuclease assay.

RESULTS

The associations between CSI and brain-derived neurotrophic factor (BDNF), FK506 binding protein (FKBP5), catechol-O-methyltransferase (COMT), or S100A10 (p11) were examined. We found CSI was associated with BDNF (OR = 1.5, 95% CI = 1.5-1.8, P = 0.0002), but not FKBP5, COMT and p11. Female soldiers reported CSI more often than males (χ2 = 7.403, p = 0.0065), although gender did not affect CSI severity. In addition, associations were found between CSI and depression, PTSD, and BDNF, but not traumatic events. The BDNF Val66Met contributed to the severity of CSI even after adjusting to PTSD, depression and LEC.

CONCLUSIONS

The associations of BDNF with CSI and its severity suggest that BDNF may be a predictor of suicidal risk and present an opportunity to develop laboratory tools with clinical implications in suicide prevention and treatment.

Neuroepigenetics of Mental Illness: The Inside Outs of the Outside Within

Epigenetics refers to environmentally sensitive modifications to DNA and chromatin that regulate gene transcription without altering the genetic sequence itself. Because of the brain's central role in a person's adaptation to dynamic changes in the environment, the field of epigenetic research is particularly pertinent for the neurosciences and mental health and illness. "Neuroepigenetics" refers to the field of epigenetics, as applied to research of the nervous system and related functional abilities. The onset and course of mental disorders revolve around person-environment interactions, i.e., the interplay between environmental factors with people (and their brain) throughout life and on the background of an individual's inherited genomic make-up. With respect to the nervous system and its functional abilities, neuroepigenetic research aims to turn the inside outs by explicating the epigenetic profiles that regulate gene expression within cells while epigenetic profiles themselves may reflect the imprints of external factors (the outside of the organism). Neuroepigenetic research is of prime importance for elucidating the molecular underpinnings of gene-environment interplay in relation to functional abilities of the brain and mental health throughout life, and thus for identifying the mechanisms underlying onset and course of mental disorders. However, neuroepigenetic research is still in its infancy and many conceptual and methodological challenges are apparent. In addition, there are considerable complexities and major challenges in conceptualizing the nature and diagnosis of mental disorders, and these need to be taken into account in studying neuroepigenetics of mental disorders. The current manuscript provides an overview and conceptual framework for neuroepigenetic research in mental disorders.