Choline up-regulates BDNF and down-regulates TrkB neurotrophin receptor in rat cortical cell culture

Childhood trauma history is linked to abnormal brain metabolism of non-medicated adult patients with major depressive disorder

OBJECTIVES

Childhood trauma is a risk factor that may lead to persistent brain metabolic abnormalities, predisposing individuals to major depressive disorder (MDD). To better elucidate the pathogenesis of MDD, we investigated the neurometabolic changes in unmedicated MDD patients who had experienced childhood trauma (CT).

METHODS

In this study, 37 unmedicated MDD patients with CT, 35 unmedicated MDD patients without CT, and 30 healthy control participants underwent high-resolution proton magnetic resonance spectroscopy (¹H-MRS) examination. Bilateral metabolic ratios of N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr in the prefrontal white matter (PWM), anterior cingulate cortex (ACC), putamen, and cerebellum were obtained.

RESULTS

MDD patients showed neurometabolic changes in the cortico-striato-cerebellar (CSC) circuit. Furthermore, MDD patients showed significantly lower NAA/Cr and higher Cho/Cr ratio in the bilateral ACC and putamen, and higher NAA/Cr and lower Cho/Cr ratio in the cerebellum. Childhood trauma reduced the Cho/Cr ratio in the left ACC, which played an important role in longer and more episodes of depression.

CONCLUSION

Early childhood trauma has a long-lasting impact on the metabolism of adult MDD patients, leading to abnormal choline metabolism of the left ACC. Abnormal biochemical metabolism in the CSC circuit may be an underlying pathophysiology of MDD.

LIMITATION

As this is a small cross-sectional study, the impact of childhood trauma on the different stages of depression has not been observed.

Enriched environment alleviates post-stroke cognitive impairment through enhancing α7-nAChR expression in rats

ABSTRACT Background: Enriched environment (EE) is a simple and effective intervention to improve cognitive function in post-stroke cognitive impairment (PSCI), partly due to the rebalancing of the cholinergic signaling pathway in the hippocampus. α7-nicotinic acetylcholine receptor (α7-nAChR) is a cholinergic receptor whose activation inhibits inflammation and promotes the recovery of neurological function in PSCI patients. However, it is still unclear whether EE can regulate α7-nAChR and activate the cholinergic anti-inflammatory pathway (CAP) in PSCI. Objective: To investigate the effects of EE on cognitive impairment, and the role of α7-nAChR in PSCI. Methods: A PSCI rat model was induced by middle cerebral artery occlusion and reperfusion (MCAO/R) and were reared in standard environment (SE) or EE for 28d, control group with sham surgery. Cognitive function was determined by Morris water maze test. The long-term potentiation (LTP) was assessed by Electrophysiology. Histopathological methods were used to determine infarct volume, α7-nAChR expression and the cytokines and cholinergic proteins expression. Results: Compared with SE group, rats in EE group had better cognitive function, higher expression of α7-nAChR positive neurons in hippocampal CA1 region. In addition, EE attenuated unfavorable changes induced by MCAO/R in cytokines and cholinergic proteins, and also enhanced LTP promoted by nicotine and attenuated by α-BGT; but showed no significantly difference in infarct volume. Conclusions: EE markedly improves cognitive impairment and enhances neuroplasticity in PSCI rats, which may be closely related to enhancement of α7-nAChR expression.

BDNF and nicotine dependence: associations and potential mechanisms

Smoking is the leading preventable cause of death worldwide and tobacco addiction has become a serious public health problem. Nicotine is the main addictive component of tobacco, and the majority of people that smoke regularly develop nicotine dependence. Nicotine addiction is deemed to be a chronic mental disorder. Although it is well known that nicotine binds to the nicotinic acetylcholine receptors (nAChRs) and activates the mesolimbic dopaminergic system (MDS) to generate the pleasant and rewarding effects, the molecular mechanisms of nicotine addiction are not fully understood. Brain-derived neurotrophic factor (BDNF) is the most prevalent growth factor in the brain, which regulates neuron survival, differentiation, and synaptic plasticity, mainly through binding to the high affinity receptor tyrosine kinase receptor B (TrkB). BDNF gene polymorphisms are associated with nicotine dependence and blood BDNF levels are altered in smokers. In this review, we discussed the effects of nicotine on BDNF expression in the brain and summarized the underlying signaling pathways, which further indicated BDNF as a key regulator in nicotine dependence. Further studies that aim to understand the neurobiological mechanism of BDNF in nicotine addcition would provide a valuable reference for quitting smoking and developing the treatment of other addictive substances.

Oral administration of porcine liver decomposition product for 4 weeks enhances visual memory and delayed recall in healthy adults over 40 years of age: A randomized, double-blind, placebo-controlled study

BACKGROUND AND OBJECTIVES

Porcine liver decomposition product (PLDP) contains neurofunctional phospholipids. We previously reported that PLDP enhances cognitive function in healthy adult humans, based on clinical evaluations using Hasegawa's Dementia Scale-Revised. In this study, we evaluated the effect of PLDP on memory indicators of the Wechsler Memory Scale-Revised (WMS-R), an internationally recognized battery for memory assessment.

METHODS

We conducted a double-blind parallel-group placebo-controlled trial to evaluate the effect of PLDP on memory. Fifty-eight participants competed the trial: 28 participants were in the PLDP group and 30 participants were in the placebo group. Each group was administered PLDP (4 capsules) or a placebo (4 capsules) for 4 continuous weeks. WMS-R was administered before and 4 weeks after PLDP or placebo intake. The data were also subdivided by age for participants under 40 years (N = 15 in PLDP; N = 15 in placebo) and over 40 years (N = 13 in PLDP, N = 15 in placebo). Changes in Verbal Memory, Visual Memory, Attention/Concentration, and Delayed Recall were analyzed.

RESULTS

No significant differences were found in any memory indicators between the PLDP group and the placebo group in pooled participants and in participants under 40 years of age. However, for participants over 40 years of age, PLDP administration resulted in a significant enhancement than placebo administration in Delayed Recall (14.1 ± 7.1 points vs. 7.1 ± 6.8 points) (P < 0.05), Visual Recall I (20.1 ± 23.1 percentile vs 1.9 ± 22.8 percentile) (P < 0.05), and Visual Recall II (24.2 ± 25.8 percentile vs 6.7 ± 19.0 percentile) (P < 0.05), respectively. The composition ratio of men to women in each group was imbalanced but no significant difference existed between the two groups.

LIMITATIONS

A modest sample size, single-center design, and a fairly short follow-up period.

CONCLUSION

PLDP enhanced Visual Memory and Delayed Recall in healthy adults over 40 years of age but not in healthy adults under 40 years of age. Therefore, PLDP may represent a promising nutraceutical that could improve cognitive function in healthy adults over 40 years of age. Further studies are required to evaluate if long term PLDP administration can prevent or delay cognitive dysfunction in healthy adults over 40 years of age.

Cell-Genotype Specific Effects of Mecp2 Mutation on Spontaneous and Nicotinic Acetylcholine Receptor-Evoked Currents in Medial Prefrontal Cortical Pyramidal Neurons in Female Rett Model Mice

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutation in the X-linked MECP2 gene. Random X-inactivation produces a mosaic of mutant (MT) and wild-type (WT) neurons in female Mecp2+/- (het) mice. Many RTT symptoms are alleviated by increasing activity in medial prefrontal cortex (mPFC) in RTT model mice (Howell et al., 2017). Using a GFP-MeCP2 fusion protein to distinguish WT from MT pyramidal neurons in mPFC we found cell autonomous (cell genotype specific) and non-autonomous effects of MeCP2 deficiency on spontaneous excitatory/inhibitory balance, nicotinic acetylcholine receptor (nAChR) currents and evoked activity. MT Layer 5 and 6 (L5, L6) neurons of male nulls, and MT L6 of het mice had reduced spontaneous excitatory synaptic input compared to WT in wild-type male (WTm), female (WTf) and het mice. Inhibitory synaptic charge in MT L6 equaled WT in 2-4-month hets. At 6-7 months inhibitory charge in WT in het slices was increased compared to both MT in het and WT in WTf; however, in hets the excitatory/inhibitory charge ratio was still greater in WT compared to MT. nAChR currents were reduced in L6 of nulls and MT L6 in het slices compared to WT neurons of het, WTm and WTf. At 2-4 months, ACh perfusion increased frequency of inhibitory currents to L6 neurons equally in all genotypes but increased excitatory inputs to MT and WT in hets less than WT in WTfs. Unexpectedly ACh perfusion evoked greater sustained IPSC and EPSC input to L5 neurons of nulls compared to WTm.

Interactions of Glutamatergic Neurotransmission and Brain-Derived Neurotrophic Factor in the Regulation of Behaviors after Nicotine Administration

Nicotine causes tobacco dependence, which may result in fatal respiratory diseases. The striatum is a key structure of forebrain basal nuclei associated with nicotine dependence. In the striatum, glutamate release is increased when α7 nicotinic acetylcholine receptors expressed in the glutamatergic terminals are exposed to nicotine, and over-stimulates glutamate receptors in gamma amino-butyric acid (GABA)ergic neurons. These receptor over-stimulations in turn potentiate GABAergic outputs to forebrain basal nuclei and contribute to the increase in psychomotor behaviors associated with nicotine dependence. In parallel with glutamate increases, nicotine exposure elevates brain-derived neurotrophic factor (BDNF) release through anterograde and retrograde targeting of the synapses of glutamatergic terminals and GABAergic neurons. This article reviews nicotine-exposure induced elevations of glutamatergic neurotransmission, the bidirectional targeting of BDNF in the striatum, and the potential regulatory role played by BDNF in behavioral responses to nicotine exposure.

Dietary docosahexaenoic acid (DHA) as lysophosphatidylcholine, but not as free acid, enriches brain DHA and improves memory in adult mice

Docosahexaenoic acid (DHA) is uniquely concentrated in the brain, and is essential for its function, but must be mostly acquired from diet. Most of the current supplements of DHA, including fish oil and krill oil, do not significantly increase brain DHA, because they are hydrolyzed to free DHA and are absorbed as triacylglycerol, whereas the transporter at blood brain barrier is specific for phospholipid form of DHA. Here we show that oral administration of DHA to normal adult mice as lysophosphatidylcholine (LPC) (40 mg DHA/kg) for 30 days increased DHA content of the brain by >2-fold. In contrast, the same amount of free DHA did not increase brain DHA, but increased the DHA in adipose tissue and heart. Moreover, LPC-DHA treatment markedly improved the spatial learning and memory, as measured by Morris water maze test, whereas free DHA had no effect. The brain derived neurotrophic factor increased in all brain regions with LPC-DHA, but not with free DHA. These studies show that dietary LPC-DHA efficiently increases brain DHA content and improves brain function in adult mammals, thus providing a novel nutraceutical approach for the prevention and treatment of neurological diseases associated with DHA deficiency, such as Alzheimer’s disease.

Synapsins regulate brain-derived neurotrophic factor-mediated synaptic potentiation and axon elongation by acting on membrane rafts

In neurons, intracellular membrane rafts are essential for specific actions of brain-derived neurotrophic factor (BDNF), which include the regulation of axon outgrowth, growth cone turning and synaptic transmission. Virtually, all the actions of BDNF are mediated by binding to its receptor, TrkB. The association of TrkB with the tyrosine kinase, Fyn, is critical for its localization to intracellular membrane rafts. Here, we show that synapsins, a family of highly amphipathic neuronal phosphoproteins, regulate membrane raft lipid composition and consequently, the ability of BDNF to regulate axon/neurite development and potentiate synaptic transmission. In the brains of mice lacking all synapsins, the expression of both BDNF and TrkB were increased, suggesting that BDNF/TrkB-mediated signaling is impaired. Consistent with this finding, synapsin-depleted neurons exhibit altered raft lipid composition, deficient targeting of Fyn to rafts, attenuated TrkB activation, and abrogation of BDNF-stimulated axon outgrowth and synaptic potentiation. Conversely, overexpression of synapsins in neuroblastoma cells results in corresponding reciprocal changes in raft lipid composition, increased localization of Fyn to rafts and promotion of BDNF-stimulated neurite formation. In the presence of synapsins, the ratio of cholesterol to estimated total phospholipids converged to 1, suggesting that synapsins act by regulating the ratio of lipids in intracellular membranes, thereby promoting lipid raft formation. These studies reveal a mechanistic link between BDNF and synapsins, impacting early development and synaptic transmission.

May BDNF Be Implicated in the Exercise-Mediated Regulation of Inflammation? Critical Review and Synthesis of Evidence

Introduction:

Exercise attenuates inflammation and enhances levels of brain-derived neurotrophic factor (BDNF). Exercise also enhances parasympathetic tone, although its role in activating the cholinergic anti-inflammatory pathway is unclear. The physiological pathways of exercise’s effect on inflammation are obscure.

Aims:

To critically review the evidence on the role of BDNF in the anti-inflammatory effects of exercise and its potential involvement in the cholinergic anti-inflammatory pathway.

Methods:

Critical literature review of studies published in MEDLINE, PubMed, CINAHL, Embase, and Cochrane databases.

Results:

BDNF is critically involved in the bidirectional signaling between immune and neurosensory cells and in the regulation of parasympathetic system responses. BDNF is also intricately involved in the inflammatory response: inflammation induces BDNF production, and, in turn, BDNF exerts pro- and/or anti-inflammatory effects. Although exercise modulates BDNF and its receptors in lymphocytes, data on BDNF’s immunoregulatory/anti-inflammatory effects in relation to exercise are scarce. Moreover, BDNF increases cholinergic activity and is modulated by parasympathetic system activation. However, its involvement in the cholinergic anti-inflammatory pathway has not been investigated.

Conclusion:

Converging lines of evidence implicate BDNF in exercise-mediated regulation of inflammation; however, data are insufficient to draw concrete conclusions. We suggest that there is a need to investigate BDNF as a potential modulator/mediator of the anti-inflammatory effects of exercise and of the cholinergic anti-inflammatory pathway during exercise. Such research would have implications for a wide range of inflammatory diseases and for planning targeted exercise protocols.

Choline protects against cardiac hypertrophy induced by increased after-load

BACKGROUND

Although inadequate intake of essential nutrient choline has been known to significantly increase cardiovascular risk, whether additional supplement of choline offering a protection against cardiac hypertrophy remain unstudied.

METHODS

The effects of choline supplements on pathological cardiac hypertrophic growth induced by transverse aorta constriction (TAC) for three weeks and cardiomyocyte hypertrophy in cultured cells induced by isoproterenol (ISO) 10 μM for 48 h stimulation were investigated. Western blot analysis and real-time PCR were used to determine the expression of ANP, BNP, β-MHC, miR-133a and Calcineurin.

RESULTS

Administration of 14 mg/kg choline to mice undergone TAC effectively attenuated the cardiac hypertrophic responses, as indicated by the reduced heart weight, left ventricular weight, ventricular thickness, and reduced expression of biomarker genes of cardiac hypertrophy. This anti-hypertrophic efficacy was reproduced in a cellular model of cardiomyocyte hypertrophy induced by isoproterenol in cultured neonatal cardiomyocytes. Our results further showed that choline rescued the aberrant downregulation of the muscle-specific microRNA miR-133a expression, a recently identified anti-hypertrophic factor, and restored the elevated calcineurin protein level, the key signaling molecule for the development of cardiac hypertrophy. These effects of choline were abolished by the M3 mAChR-specific antagonist 4-DAMP.

CONCLUSION

Our study unraveled for the first time the cardioprotection of choline against cardiac hypertrophy, with correction of expression of miR-133a and calcineurin as a possible mechanism. Our findings suggest that choline supplement may be considered for adjunct anti-hypertrophy therapy.

Mitochondrial localized STAT3 is involved in NGF induced neurite outgrowth

Background

Signal transducer and activator of transcription 3 (STAT3) plays critical roles in neural development and is increasingly recognized as a major mediator of injury response in the nervous system. Cytokines and growth factors are known to phosphorylate STAT3 at tyrosine⁷⁰⁵ with or without the concomitant phosphorylation at serine⁷²⁷, resulting in the nuclear localization of STAT3 and subsequent transcriptional activation of genes. Recent evidence suggests that STAT3 may control cell function via alternative mechanisms independent of its transcriptional activity. Currently, the involvement of STAT3 mono-phosphorylated at residue serine⁷²⁷ (P-Ser-STAT3) in neurite outgrowth and the underlying mechanism is largely unknown.

Principal Findings

In this study, we investigated the role of nerve growth factor (NGF) induced P-Ser-STAT3 in mediating neurite outgrowth. NGF induced the phosphorylation of residue serine⁷²⁷ but not tyrosine⁷⁰⁵ of STAT3 in PC12 and primary cortical neuronal cells. In PC12 cells, serine but not tyrosine dominant negative mutant of STAT3 was found to impair NGF induced neurite outgrowth. Unexpectedly, NGF induced P-Ser-STAT3 was localized to the mitochondria but not in the nucleus. Mitochondrial STAT3 was further found to be intimately involved in NGF induced neurite outgrowth and the production of reactive oxygen species (ROS).

Conclusion

Taken together, the findings herein demonstrated a hitherto unrecognized novel transcription independent mechanism whereby the mitochondria localized P-Ser-STAT3 is involved in NGF induced neurite outgrowth.