Dysregulation of astrocytic mitochondrial function following exposure to a dopamine metabolite: Implications for Parkinson's disease

A functional analysis of a resorbable citrate-based composite tendon anchor

Rapid and efficient tendon fixation to a bone following trauma or in response to degenerative processes can be facilitated using a tendon anchoring device. Osteomimetic biomaterials, and in particular, bio-resorbable polymer composites designed to match the mineral phase content of native bone, have been shown to exhibit osteoinductive and osteoconductive properties in vivo and have been used in bone fixation for the past 2 decades. In this study, a resorbable, bioactive, and mechanically robust citrate-based composite formulated from poly(octamethylene citrate) (POC) and hydroxyapatite (HA) (POC-HA) was investigated as a potential tendon-fixation biomaterial. In vitro analysis with human Mesenchymal Stem Cells (hMSCs) indicated that POC-HA composite materials supported cell adhesion, growth, and proliferation and increased calcium deposition, alkaline phosphatase production, the expression of osteogenic specific genes, and activation of canonical pathways leading to osteoinduction and osteoconduction. Further, in vivo evaluation of a POC-HA tendon fixation device in a sheep metaphyseal model indicates the regenerative and remodeling potential of this citrate-based composite material. Together, this study presents a comprehensive in vitro and in vivo analysis of the functional response to a citrate-derived composite tendon anchor and indicates that citrate-based HA composites offer improved mechanical and osteogenic properties relative to commonly used resorbable tendon anchor devices formulated from poly(L-co-D, l-lactic acid) and tricalcium phosphate PLDLA-TCP.

20- Deoxyingenol attenuate morphine-induced hippocampus neurotoxicity and memory impairments in rats

Objective

The present study aimed to see if 20-Deoxyingenol(20-DOI) could protect hippocampus neurons from the neurotoxic effects of morphine and reduce memory loss in rats.

Method

Male Wistar rats were given morphine hydrochloride (45 mg/kg, sc, four weeks) and 20-DOI (10, 20 mg/kg, ip., coadministered with morphine) for the Morris Water Maze (MWM) test to investigate the effects of 20-DOI on spatial learning and memory. Western blotting was used to evaluate the expression of the hippocampal CA1 region of the cleaved caspase-3, Bax, and Bcl2 proteins and so on. Moreover, these assays were used to evaluate the expression of superoxide dismutase (SOD)2, heme oxygenase 1(HO1) protein, and glutathione peroxidase (GPx) activity within the hippocampus CA1 area.

Results

The administration of 20-DOI (10 and 20 mg/kg) to morphine-treated mice enhanced spatial learning and reduced memory deficits. Additionally, 20-DOI treatment reduced apoptosis and oxidative stress in the hippocampal CA1 region of morphine-treated rats. Moreover, 20-DOI improved the autophagy level of the hippocampal CA1 area of morphine-treated rats using Transcription factor EB (TFEB), and 20-DOI prevented spatial learning and memory impairment in morphine-treated rats. The current observation could be partially due to the inhibition of neuronal apoptosis and oxidative stress in the hippocampal CA1 region of rats treated with morphine and the improved autophagy in this region.

Conclusions

20-DOI attenuated morphine administration in rats with chronic disease caused spatial learning and memory dysfunction. These mechanistic effects could be partially related to 20-DOI protecting the CA1 region of rat hippocampal neurons from the morphine-induced oxidative stress, apoptosis, and autophagy through TFEB.

Chrysophanol accelerates astrocytic mitochondria transfer to neurons and attenuates the cerebral ischemia-reperfusion injury in rats

Astrocytes transfer extracellular functional mitochondria into neurons to rescue injured neurons after a stroke. However, there are no reports on drugs that interfere with intercellular mitochondrial transfer. Chrysophanol (CHR) was an effective drug for the treatment of cerebral ischemia-reperfusion injury (CIRI) and was selected as the test drug. The oxygen-glucose deprivation/reoxygenation (OGD/R) cell model and the middle cerebral artery occlusion animal model were established to investigate the effect of CHR on CIRI. The result showed that astrocytes could act as mitochondrial donors to ameliorate neuronal injury. Additionally, the neuroprotective effect of astrocytes was enhanced by CHR, the CHR improved the neuronal mitochondrial function, decreased the neurological deficit score and infarction volume, recovered cell morphology in ischemic penumbra. The mitochondrial fluorescence probe labeling technique has shown that the protective effect of CHR is associated with accelerated astrocytic mitochondrial transfer to neurons. The intercellular mitochondrial transfer may be an important way to ameliorate ischemic brain injury and be used as a key target for drug treatment.

Prodromal Parkinson's disease and the catecholaldehyde hypothesis: Insight from olfactory bulb organotypic cultures

Parkinson's disease (PD) is a progressive, neurodegenerative disorder with an increasing incidence, unknown etiology, and is currently incurable. Advances in understanding the pathological mechanisms at a molecular level have been slow, with little attention focused on the early prodromal phase of the disease. Consequently, the development of early-acting disease-modifying therapies has been hindered. The olfactory bulb (OB), the brain region responsible for initial processing of olfactory information, is particularly affected early in PD at both functional and molecular levels but there is little information on how the cells in this region are affected by disease. Organotypic and primary OB cultures were developed and characterized. These platforms were then used to assess the effects of 3,4-dihydroxyphenylacetylaldehyde (DOPAL), a metabolite of dopamine present in increased levels in post-mortem PD tissue and which is thought to contribute to PD pathogenesis. Our findings showed that DOPAL exposure can recapitulate many aspects of PD pathology. Oxidative stress, depolarization of mitochondrial membranes, and neurodegeneration were all induced by DOPAL addition, as were measured transcriptomic changes consistent with those reported in PD clinical studies. These olfactory models of prodromal disease lend credence to the catecholaldehyde hypothesis of PD and provide insight into the mechanisms by which the OB may be involved in disease progression.

Micromotion Derived Fluid Shear Stress Mediates Peri-Electrode Gliosis through Mechanosensitive Ion Channels

The development of bioelectronic neural implant technologies has advanced significantly over the past 5 years, particularly in brain-machine interfaces and electronic medicine. However, neuroelectrode-based therapies require invasive neurosurgery and can subject neural tissues to micromotion-induced mechanical shear, leading to chronic inflammation, the formation of a peri-electrode void and the deposition of reactive glial scar tissue. These structures act as physical barriers, hindering electrical signal propagation and reducing neural implant functionality. Although well documented, the mechanisms behind the initiation and progression of these processes are poorly understood. Herein, in silico analysis of micromotion-induced peri-electrode void progression and gliosis is described. Subsequently, ventral mesencephalic cells exposed to milliscale fluid shear stress in vitro exhibited increased expression of gliosis-associated proteins and overexpression of mechanosensitive ion channels PIEZO1 (piezo-type mechanosensitive ion channel component 1) and TRPA1 (transient receptor potential ankyrin 1), effects further confirmed in vivo in a rat model of peri-electrode gliosis. Furthermore, in vitro analysis indicates that chemical inhibition/activation of PIEZO1 affects fluid shear stress mediated astrocyte reactivity in a mitochondrial-dependent manner. Together, the results suggest that mechanosensitive ion channels play a major role in the development of a peri-electrode void and micromotion-induced glial scarring at the peri-electrode region.

Scavenging neurotoxic aldehydes using lysine carbon dots

Reactive aldehydes generated in cells and tissues are associated with adverse physiological effects. Dihydroxyphenylacetaldehyde (DOPAL), the biogenic aldehyde enzymatically produced from dopamine, is cytotoxic, generates reactive oxygen species, and triggers aggregation of proteins such as α-synuclein implicated in Parkinson's disease. Here, we demonstrate that carbon dots (C-dots) prepared from lysine as the carbonaceous precursor bind DOPAL molecules through interactions between the aldehyde units and amine residues on the C-dot surface. A set of biophysical and in vitro experiments attests to attenuation of the adverse biological activity of DOPAL. In particular, we show that the lysine-C-dots inhibit DOPAL-induced α-synuclein oligomerization and cytotoxicity. This work underlines the potential of lysine-C-dots as an effective therapeutic vehicle for aldehyde scavenging.

Metabolic Signature of Energy Metabolism Alterations and Excess Nitric Oxide Production in Culture Media Correlate with Low Human Embryo Quality and Unsuccessful Pregnancy

Notwithstanding the great improvement of ART, the overall rate of successful pregnancies from implanted human embryos is definitely low. The current routine embryo quality assessment is performed only through morphological criteria, which has poor predictive capacity since only a minor percentage of those in the highest class give rise to successful pregnancy. Previous studies highlighted the potentiality of the analysis of metabolites in human embryo culture media, useful for the selection of embryos for implantation. In the present study, we analyzed in blind 66 human embryo culture media at 5 days after in vitro fertilization with the aim of quantifying compounds released by cell metabolism that were not present as normal constituents of the human embryo growth media, including purines, pyrimidines, nitrite, and nitrate. Only some purines were detectable (hypoxanthine and uric acid) in the majority of samples, while nitrite and nitrate were always detectable. When matching biochemical results with morphological evaluation, it was found that low grade embryos (n = 12) had significantly higher levels of all the compounds of interest. Moreover, when matching biochemical results according to successful (n = 17) or unsuccessful (n = 25) pregnancy, it was found that human embryos from the latter group released higher concentrations of hypoxanthine, uric acid, nitrite, and nitrate in the culture media. Additionally, those embryos that developed into successful pregnancies were all associated with the birth of healthy newborns. These results, although carried out on a relatively low number of samples, indicate that the analysis of the aforementioned compounds in the culture media of human embryos is a potentially useful tool for the selection of embryos for implantation, possibly leading to an increase in the overall rate of ART.

The interplay of dopamine metabolism abnormalities and mitochondrial defects in the pathogenesis of schizophrenia

Dopamine (DA) is a major monoamine neurotransmitter in the brain and has essential roles in higher functions of the brain. Malfunctions of dopaminergic signaling have been implicated in various mental disorders such as addiction, attention deficit/hyperactivity disorder, Huntington's disease, Parkinson's disease (PD), and schizophrenia. The pathogenesis of PD and schizophrenia involves the interplay of mitochondrial defect and DA metabolism abnormalities. This article focuses on this issue in schizophrenia. It started with the introduction of metabolism, behavioral action, and physiology of DA, followed by reviewing evidence for malfunctions of dopaminergic signaling in patients with schizophrenia. Then it provided an overview of multiple facets of mitochondrial physiology before summarizing mitochondrial defects reported in clinical studies with schizophrenia patients. Finally, it discussed the interplay between DA metabolism abnormalities and mitochondrial defects and outlined some clinical studies showing effects of combination therapy of antipsychotics and antioxidants in treating patients with schizophrenia. The update and integration of these lines of information may advance our understanding of the etiology, pathogenesis, phenomenology, and treatment of schizophrenia.

Metabolomic and Lipidomic Profiling of Preoperative CSF in Elderly Hip Fracture Patients With Postoperative Delirium

Objective

To investigate dysregulated molecules in preoperative cerebrospinal fluid (CSF) of elderly hip fracture patients with postoperative delirium (POD), in order to identify potential pathological mechanisms and biomarkers for pre-stage POD.

Materials and Methods

This nested case control study used untargeted metabolomic and lipidomic analysis to profile the preoperative CSF of patients (n = 40) who developed POD undergone hip fracture surgery (n = 10) and those who did not (n = 30). Thirty Non-POD patients were matched to 10 POD patients by age (± 2 years) and Mini Mental State Examination score (± 2 points). CSF was collected after successful spinal anesthesia and banked for subsequent analysis. On the first two postoperative days, patients were assessed twice daily using the Confusion Assessment Method-Chinese Revision. CSF samples from the two groups were analyzed to investigate possible relevant pathological mechanisms and identify candidate biomarkers.

Results

Demographic characteristics of the groups were matched. Eighteen metabolites and thirty-three lipids were dysregulated in the preoperative CSF of POD patients. Pathway enrichment analysis revealed perturbations in D-glutamine and D-glutamate metabolism; glycerophospholipid metabolism; alanine, aspartate and glutamate metabolism; sphingolipid metabolism; histidine metabolism; and arginine biosynthesis at the pre-delirium stage. Receiver operating characteristic curve analysis indicated that phosphatidylethanolamine (PE, 40:7e), with an area under the curve value of 0.92, is a potential biomarker for POD.

Conclusion

Multiple pathological mechanisms in the POD group were involved before surgery, including neuroinflammation, oxidative stress, and energy metabolism disorders induced by hypoxia, as well as neurotransmitter imbalances such as increased dopamine and glutamate, and decreased glutamine. These metabolic abnormalities potentially increase the fragility of the brain, thus contributing to POD. PE (40:7e) might be a potential biomarker for POD. Not only do our results provide potential biomarkers for POD, but also provide information for deep pathological research.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier ChiCTR1900021533.