Impairments in Brain-Derived Neurotrophic Factor-Induced Glutamate Release in Cultured Cortical Neurons Derived from Rats with Intrauterine Growth Retardation: Possible Involvement of Suppression of TrkB/Phospholipase C-γ Activation

Untargeted metabolomics analysis of the hippocampus and cerebral cortex identified the neuroprotective mechanisms of Bushen Tiansui formula in an aβ25-35-induced rat model of Alzheimer’s disease

Background: Bushen Tiansui Formula (BSTSF) is a traditional formulation of Chinese medicine that has been used to treat Alzheimer’s disease (AD) for decades; however, the underlying mechanisms by which this formula achieves such therapeutic effects have yet to be elucidated.

Prupose: To investigate the neuroprotective mechanisms of BSTSF against AD by analyzing metabolite profiles in the hippocampus and cortex of AD rats.

Methods: The rat models of AD were established by the injection of Aβ_25–35. The Morris water maze (MWM) test was performed to evaluate the effect of BSTSF treatment on cognitive dysfunction. Hematoxylin and eosin (HE) staining was used to assess the effect of BSTSF on typical AD pathologies. Underlying mechanisms were investigated using LC-MS/MS-based untargeted metabolomics analysis of the cerebral cortex and hippocampus.

Results: BSTSF significantly improved memory deficits and the typical histopathological changes of AD rats. Untargeted metabolomics analysis showed that 145 and 184 endogenous metabolites in the cerebral cortex and hippocampus, respectively, were significantly different in the BSTSF group when compared with the AD group. The differential metabolites in the cerebral cortex were primarily involved in cysteine and methionine metabolism, while those in the hippocampus were mainly involved in d-Glutamine and d-glutamate metabolism.

Conclusion: In the present study, we confirmed the neuroprotective effects of BSTSF treatment against AD using a rat model. Our findings indicate that the BSTSF-mediated protective effects were associated with amelioration of metabolic disorders in the hippocampus and cerebral cortex.

Mechanisms Underlying Neurologic Injury in Intrauterine Growth Restriction

Intrauterine growth restriction is a condition that prevents normal fetal development, and previous studies have reported that intrauterine growth restriction is caused by adverse intrauterine factors. This condition affects both short- and long-term neurodevelopmental disorders. Studies have revealed that neurodevelopmental disorders can contribute to gray and white matter damage and decrease the brain volume of affected individuals. Further, these disorders are associated with increased risks of mental retardation, cognitive impairment, and cerebral palsy, which seriously affect the quality of life. Although the mechanisms underlying the neurologic injury associated with intrauterine growth restriction are not completely clear, studies have revealed that neuronal apoptosis, neuroinflammation, oxidative stress, excitatory toxicity, disruption of blood-brain barrier, and epigenetics may be involved in this process. This article reviews the manifestations and possible mechanisms underlying neurologic injury in intrauterine growth restriction and provides a theoretical basis for the effective prevention and treatment of this condition.

Intravenous infusion of xenon-containing liposomes generates rapid antidepressant-like effects

AIM

Similar to ketamine, xenon gas acts as a glutamatergic N-methyl-d-aspartate receptor antagonist, but devoid of propensity to cause untoward effects. Herein, we loaded xenon gas into a liposomal carrier called xenon-containing liposomes (Xe-liposome) for systemic delivery, and investigated its effect as an antidepressant and also analyzed synaptic biomarkers including brain-derived neurotrophic factor (BDNF), protein kinase B (AKT), mammalian target of rapamycin (mTOR), protein kinase C (PKC) and extracellular signal-regulated kinase-1/2 (ERK1/2) in blood and brain.

METHODS

Xe-liposomes (15 μl/mg) were prepared by a pressurized freeze-thaw method, and injected via the lateral tail vein (0.6 mL/rat) in male Wistar rats. The uncaging of xenon gas from circulating Xe-liposome was facilitated by continuous ultrasound application externally on the neck over the internal common carotid artery. One-hour after Xe-liposome infusion, animals were assessed for depression-like behaviors using a forced swimming test (FST), and spontaneous locomotor activity. Blood, as well as frontal cortex and hippocampal samples were obtained for immunoblotting and/or enzyme-linked immune sorbent assays.

RESULTS

Acute intravenous infusion of Xe-liposome, at 6 mg/kg, showed an increase in swimming time in the FST (p < 0.006), indicating antidepressant-like phenotypes. Higher doses of Xe-liposomes (9 mg/kg) failed to improve swimming duration. This behavioral discrepancy was not associated with locomotion aberrations, as gross activity of rats remained similar for both doses. In biochemical analyses of frontal cortex, protein levels of BDNF increased by 64%, and enhanced phosphorylation of AKT (43%) and mTOR (93%) was observed at the 6 mg/kg dose level of Xe-liposomes, while these biomarkers and phosphorylated PKC and ERK1/2 levels remained unchanged at the higher dose. Moreover, Xe-liposomal treatment did not change the plasma and protein levels of BDNF, and phosphorylated AKT, mTOR, PKC and ERK1/2 hippocampal expressions.

CONCLUSION

Xe-liposomes mediate a rapid antidepressant-like effect through activation of AKT/mTOR/BDNF signaling pathway.

Electroacupuncture ameliorate learning and memory by improving N-acetylaspartate and glutamate metabolism in APP/PS1 mice

Objective

To explore the precise mechanism of electroacupuncture (EA) to delay cognitive impairment in Alzheimer disease.

Methods

N-Acetylaspartate (NAA), glutamate (Glu) and myoinositol (mI) metabolism were measured by magnetic resonance spectroscopy, learning and memory of APP/PS1 mouse was evaluated by the Morris water maze test and the step-down avoidance test, neuron survival number and neuronal structure in the hippocampus were observed by Nissl staining, and BDNF and phosphorylated TrkB detected by Western blot.

Results

EA at DU20 acupuncture significantly improve learning and memory in behavioral tests, up-regulate NAA, Glu and mI metabolism, increase the surviving neurons in hippocampus, and promote the expression of BDNF and TrkB in the APP/PS1 transgenic mice.

Conclusion

These findings suggested that EA is a potential therapeutic for ameliorate cognitive dysfunction, and it might be due to EA could improve NAA and Glu metabolism by upregulation of BDNF in APP/PS1 mice.

In SilicoModel-driven Assessment of the Effects of Brain-derived Neurotrophic Factor Deficiency on Glutamate and Gamma-Aminobutyric Acid: Implications for Understanding Schizophrenia Pathophysiology

Objective

Deficient brain-derived neurotrophic factor (BDNF) is one of the important mechanisms underlying the neuroplasticity abnormalities in schizophrenia. Aberration in BDNF signaling pathways directly or circuitously influences neurotransmitters like glutamate and gamma-aminobutyric acid (GABA). For the first time, this study attempts to construct and simulate the BDNF-neurotransmitter network in order to assess the effects of BDNF deficiency on glutamate and GABA.

Methods

Using CellDesigner, we modeled BDNF interactions with calcium influx via N-methyl-D-aspartate receptor (NMDAR)- Calmodulin activation; synthesis of GABA via cell cycle regulators protein kinase B, glycogen synthase kinase and β-catenin; transportation of glutamate and GABA. Steady state stability, perturbation time-course simulation and sensitivity analysis were performed in COPASI after assigning the kinetic functions, optimizing the unknown parameters using random search and genetic algorithm.

Results

Study observations suggest that increased glutamate in hippocampus, similar to that seen in schizophrenia, could potentially be contributed by indirect pathway originated from BDNF. Deficient BDNF could suppress Glutamate decarboxylase 67-mediated GABA synthesis. Further, deficient BDNF corresponded to impaired transport via vesicular glutamate transporter, thereby further increasing the intracellular glutamate in GABAergic and glutamatergic cells. BDNF also altered calcium dependent neuroplasticity via NMDAR modulation. Sensitivity analysis showed that Calmodulin, cAMP response element-binding protein (CREB) and CREB regulated transcription coactivator-1 played significant role in this network.

Conclusion

The study presents in silicoquantitative model of biochemical network constituting the key signaling molecules implicated in schizophrenia pathogenesis. It provides mechanistic insights into putative contribution of deficient BNDF towards alterations in neurotransmitters and neuroplasticity that are consistent with current understanding of the disorder.

Impairment and reorganization of the phosphoinositide-specific phospholipase C enzymes in suicide brains

A number of studies suggested that suicide may be associated with specific neurobiological abnormalities. Neurobiology studies focused upon abnormalities of signalling mechanisms with special regard to the serotonin system and the related Phosphoinositide (PI) signalling system. Previous data suggested the involvement of the PI-specific phospholipase C (PLC) family in neuropsychiatric disorders. By using PCR and morphological microscopy observation we examined the whole panel of expression of PLC isoforms in the brains of 28 individuals who committed suicide and in normal controls in order to evaluate the involvement of specific PLC isoforms. The overall PLC expression was reduced and a complex reorganization of the isoforms was observed. The knowledge of the complex network of neurobiological molecules and interconnected signal transduction pathways in the brain of suicide victims might be helpful to understand the natural history and the pathogenesis of the suicidal behavior. That might lead to obtain prognostic suggestions in order to prevent suicide and to new therapeutic agents targeting specific sites in this signalling cascade.