Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays,presynaptic dopaminergic positron emission tomography,which assesses deficiencies in dopamine synthesis,storage,and transport,is widely utilized for early diagnosis and differential diagnosis of parkinsonism.This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism.We conducted a thorough literature search using reputable databases such as PubMed and Web of Science.Selection criteria involved identifying peer-reviewed articles published within the last 5 years,with emphasis on their relevance to clinical applications.The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis.Moreover,when employed in conjunction with other imaging modalities and advanced analytical methods,presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker.This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion.In summary,the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials,ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

TDP-43 overexpression impairs presynaptic integrity

The pathological mechanisms associated with the trans-activating response DNA/RNA binding protein（TDP）-43 remain largely enigmatic.Accumulation,insolubility and post-translational modification of nuclear and cytoplasmic TDP-43 are evident in many neurodegenerative diseases.TDP-43 constitutes one of the major molecular pathologies associated with RNA metabolism.

Role of presynaptic calcium stores for neural network dysfunction in Alzheimer＇s disease

Alzheimer’s disease（AD）is the most common form of dementia representing a major problem for public health.In 2017 there were an estimated 50 million patients worldwide and this number is expected to almost double every 20years,reaching 75 million in 2030 and 131.5 million in 2050（https：//www.alz.co.uk/research/statistics）.

Effects of Propofol on Glutamate-Induced Calcium Mobilization in Presynaptic Boutons of Rat Hippocampal Neurons

Recent reports have suggested that various general anesthetics affect presynaptic processes in the central nervous system. However, characterizations of the influence of intravenous anesthetics on neurotransmitter release from presynaptic nerve terminals (boutons) are insufficient. Because the presynaptic calcium concentration ([Ca2+]pre) regulates neurotransmitter release, we investigate the effects of the intravenous anesthetic propofol on neurotransmitter release by measuring [Ca2+]pre in the presynaptic boutons of individual dissociated hippocampal neurons. Brain slices were prepared from Sprague–Dawley rats (10 - 14 days of age). The hippocampal CA1 area was isolated with a fire-polished glass pipette, which vibrated horizontally to dissociate hippocampal CA1 neurons along with their attached presynaptic boutons. Presynaptic boutons were visualized under a confocal laser scanning microscope after staining with FM1-43 dye, and [Ca2+]pre was measured using fluo-3 AM dye. Glutamate (3 – 100 μM) administration increased [Ca2+]pre in Ca2+- containing external solution in a concentration-dependent manner. Propofol (3 – 30 μM) dose-dependently suppressed this glutamate (30 μM)-induced increase in [Ca2+]pre in boutons attached to dendrites, but not to the soma or base of the dendritic tree. The large majority of excitatory synapses on CA1 neurons are located on dendritic spines;therefore, propofol may affect glutamate-induced Ca2+ mobilization in excitatory, but not inhibitory, presynaptic boutons. Propofol may possibly have some effect on glutamate-regulated neurotransmitter release from excitatory presynaptic nerve terminals through inhibiting the increase in [Ca2+]pre induced by glutamate.

Crystallization adn molecular aggregation of presynaptic neurotoxin from Agkistrodon halys pallas

Phospholipase A2 catalyzes specially the hydrolysis of the ester bond at the C2 position of3-sn-phosphoglycerides. Besides the enzymatic activity, the venom phospholipase A2 from varioussources displays complicated pharmacological activity and toxicity. The phospholipaseA2 neurotoxin is a noteworthy group in all phospholipase A2 species. It has been

Presynaptic mechanisms at prefrontal synapses involved in persistent pain

The cumulative evidence from animal and human studies revealed that the anterior cingulate cortex (ACC) plays essential roles in pain sensation and persistent pain. It has been evident in the ACC synapses of animals that changes in both the presynaptic and postsynaptic function are caused by peripheral nerve injury. Thus far, postsynaptic changes in the ACC following nerve injury have been primarily studied to understand the mechanisms of chronic pain. In recent years, studies focusing on the presynaptic mechanisms in chronic pain have been progressively increased. In this review, I will discuss molecular mechanisms associated with chronic pain and presynaptic form of long-term potentiation. I will also discuss evidence for presynaptic changes in the ACC caused by disease-related pain.

Selective deletion of zinc transporter 3 in amacrine cells promotes retinal ganglion cell survival and optic nerve regeneration after injury

Vision depends on accurate signal conduction from the retina to the brain through the optic nerve,an important part of the central nervous system that consists of bundles of axons originating from retinal ganglion cells.The mammalian optic nerve,an important part of the central nervous system,cannot regenerate once it is injured,leading to permanent vision loss.To date,there is no clinical treatment that can regenerate the optic nerve and restore vision.Our previous study found that the mobile zinc(Zn^(2+))level increased rapidly after optic nerve injury in the retina,specifically in the vesicles of the inner plexiform layer.Furthermore,chelating Zn^(2+)significantly promoted axonal regeneration with a long-term effect.In this study,we conditionally knocked out zinc transporter 3(ZnT3)in amacrine cells or retinal ganglion cells to construct two transgenic mouse lines(VGAT^(Cre)ZnT3^(fl/fl)and VGLUT2^(Cre)ZnT3^(fl/fl),respectively).We obtained direct evidence that the rapidly increased mobile Zn^(2+)in response to injury was from amacrine cells.We also found that selective deletion of ZnT3 in amacrine cells promoted retinal ganglion cell survival and axonal regeneration after optic nerve crush injury,improved retinal ganglion cell function,and promoted vision recovery.Sequencing analysis of reginal ganglion cells revealed that inhibiting the release of presynaptic Zn^(2+)affected the transcription of key genes related to the survival of retinal ganglion cells in postsynaptic neurons,regulated the synaptic connection between amacrine cells and retinal ganglion cells,and affected the fate of retinal ganglion cells.These results suggest that amacrine cells release Zn^(2+)to trigger transcriptomic changes related to neuronal growth and survival in reginal ganglion cells,thereby influencing the synaptic plasticity of retinal networks.These results make the theory of zinc-dependent retinal ganglion cell death more accurate and complete and provide new insights into the complex interactions between retinal cell networks.

主旨报告

PL-1 Presynaptic Endosomal Cathepsin D Regulates the Biogenesis of GABAergic Synaptic Vesicles DUAN Shu-min Zhejiang University School of Medicine,Hangzhou,310058,China Dr. Shumin Duan is a professor at Zhejiang University School of Medicine,China. He got his Ph. D. from Kyushu University in Japan in 1991 and received a postdoctoral training at University of Hawaii and University of California at San Francisco during 1997-1999. His research interests include the function and the mechanisms of neuronglia interactions in health and disease and neural circuit mechanisms of brain functions. He is an academician of Chinese Academy of Sciences and a member of the Academy of Sciences for the Developing World (TWAS). He is the president of Chinese Society for Neuroscience and a council member of International Brain Research Organization. He serves as the Editor-in-Chief of Neuroscience Bulletin and an editorial board member in several international neuroscience journals.

Toosendanin-induced change of dopamine level detected by microdialysis in vivo at rat striatum

To investigate the effect on central nervous transmission of toosendanin (TSN), a presynaptic blocker, rat striatum was perfused in vivo with a TSN-containing artificial cere-brospinal fluid (ACSF) and the level of dopamine (DA) as well as related metabolites in the collected dialysates has been determined by a microbore HPLC with electrochemical detection (mi-crobore HPLC-ECD). The results are as follows: ( i ) TSN induced a biphasic change of DA from its basal level;( ii ) the basal contents of two metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) increased in turn and stayed at a higher level than basal control for a long period. The basal level of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of 5-hydroxytryptamine(5-HT), had a change similar to that of HVA; (iii) after per-fusion with TSN-containing ACSF, high K+-evoked DA release was inhibited. These results show that TSN does not selectively affect acetylcholine (ACh) release, but probably acts on a common

Unraveling the mechanisms of synapse formation and axon regeneration: the awesome power of C. elegans genetics

Since Caenorhabditis elegans was chosen as a model organism by Sydney Brenner in 1960's, genetic studies in this organism have been instrumental in discovering the function of genes and in deciphering molecular signaling network. The small size of the organism and the simple nervous system enable the complete reconstruction of the first connectome. The stereotypic developmental program and the anatomical reproducibility of synaptic connections provide a blueprint to dissect the mechanisms underlying synapse formation. Recent technological innovation using laser surgery of single axons and in vivo imaging has also made C. elegans a new model for axon regeneration. Importantly, genes regulating synaptogenesis and axon regeneration are highly conserved in function across animal phyla. This mini-review will summarize the main approaches and the key findings in understanding the mechanisms underlying the development and maintenance of the nervous system. The impact of such findings underscores the awesome power of C. elegans genetics.

Effects and wavelet spectral entropy analysis of rhubarb extracts rhein on synaptic transmission in rat hippocampal ca1 area in vitro

Background 5-dihydroxyanthraquinone-2-carboxylic acid (rhein) inhibits oxidoreduction induced by reducing nicotingamide adenine dinucleotide in the mitochondria and reducing reactive oxygen species, it also suppresses lipid peroxidation in rat brain homogenates. This study was to assess the effects of anthraquinone derivatives, rhein on synaptic transmission in the rat hippocampal CA_1 pyramidal cell layer by intracellular recording.Methods The excitatory postsynaptic potential (EPSP) evoked by stimulation of the Schaffer collaterals in the presence of bicuculline (15 μmol/L) was depressed by application of rhein (0.3-30 μmol/L). The amplitude of the EPSP was restored within 20 minutes after removal of rhein from the supernatant. At a concentration of 30 μmol/L, rhein reduced the amplitude of the EPSP to 42%±3.7% (n=24) of the control. Subsequently, wavelet spectral entropy was used to analyze the EPSP. Results A strong positive correlation was observed between the wavelet spectral entropy and other parameters such as amplitude, slope of rising phase and slope of descending phase of the EPSP. The paired-pulse facilitation (PPF) of the EPSP was significantly increased by rhein (30 μmol/L). The inhibitory postsynaptic potential (IPSP) recorded in the presence of CNQX (20 μmol/L) and APV (40 μmol/L) is not altered by rhein (30 μmol/L). Conclusions Rhein (30 μmol/L) can decrease the frequency but not the amplitude of the miniature EPSP (mEPSP). It is suggested that rhein inhibits excitatory synaptic transmission by decreasing the release of glutamate in rat hippocampal CA_1 pyramidal neurons.

Association of variants in the KIF1A gene with amyotrophic lateral sclerosis

Background:Amyotrophic lateral sclerosis(ALS)is a devastating progressive neurodegenerative disease that affects neurons in the central nervous system and the spinal cord.As in many other neurodegenerative disorders,the genetic risk factors and pathogenesis of ALS involve dysregulation of cytoskeleton and neuronal transport.Notably,sen-sory and motor neuron diseases such as hereditary sensory and autonomic neuropathy type 2(HSAN2)and spastic paraplegia 30(SPG30)share several causative genes with ALS,as well as having common clinical phenotypes.KIF1A encodes a kinesin 3 motor that transports presynaptic vesicle precursors(SVPs)and dense core vesicles and has been reported as a causative gene for HSAN2 and SPG30.Methods:Here,we analyzed whole-exome sequencing data from 941 patients with ALS to investigate the genetic association of KIF1A with ALS.Results:We identified rare damage variants(RDVs)in the KIF1A gene associated with ALS and delineated the clini-cal characteristics of ALS patients with KIF1A RDVs.Clinically,these patients tended to exhibit sensory disturbance.Interestingly,the majority of these variants are located at the C-terminal cargo-binding region of the KIF1A protein.Functional examination revealed that the ALS-associated KIF1A variants located in the C-terminal region preferentially enhanced the binding of SVPs containing RAB3A,VAMP2,and synaptophysin.Expression of several disease-related KIF1A mutants in cultured mouse cortical neurons led to enhanced colocalization of RAB3A or VAMP2 with the KIF1A motor.Conclusions:Our study highlighted the importance of KIF1A motor-mediated transport in the pathogenesis of ALS,indicating KIF1A as an important player in the oligogenic scenario of ALS.

Purification and partial amino acid sequences of a new presynaplic toxin and a cytotoxin from venom of pit veper Agkistrodon blomhoffii brevicaudus

The technique of the reverse-phase performance liquid chromatography (RP-HPLC) was employed to separate and purify the toxic proteins from the venom of Agkistrodon blomhoffii brevicaudus collected in China 3 toxic proteins marked as AgTx-1, AgTx-2 and AgTx-3 consisting of about 122 amino acid residues were screened The toxicities (LD50,) of the AgTx-1, AgTx-2 and AgTx-3 were 0.075, 0.51 and 6.6 mg per kg weight of mice respectively. Toxicological experiment in the chick biventer cervicis nerve-muscle preparation showed that the acetylcholine (Ach) sensitivity of the preparation was unchanged after the total failure of the indirect contraction caused by AgTx-1 and AgTx-2. suggesting that they were presynaptic blockers, namely β-type of snake toxins. However, the amplitude of indirect contraction of the preparation was gradually reduced due to its incomplete relaxation caused by AgTx-3, indicating that it should belong to the category of cytotoxins. The partial amino acid sequences of 3 toxins have been established. It was found in ref. [1] that the sequences of the first 32 N-terminal ammo acid residues of AgTx-1 and AgTx-2, as well as β -agkistrodotoxin (β-AgTx) reported previously were identical (the residue at the position 30 of β-AgTx should be Trp). In view of the similarity in toxicities, and the amounts in the venom and other properties, it was concluded that AgTx-1 should be β-AgTx and consequently was renamed β1-AgTx. AgTx-2 should be the isoform of β1-AgTx, and correspondingly named β2-AgTx.

PRELIMINARY CRYSTALLOGRAPHIC STUDIES OF THE NEUTRAL PHOSPHOLIPASE A_2 FROM THE VENOM OF Agkistroaon halys PALLAS

Phospholipase A2（EC3.1.1.4） catalyzes the hydrolysis of the ester bond at the C2 position of 3-Sn-phosphoglycerides, and is central to studies in phospholipid structure, and in interactions of protein with phospholipid and biological membrane. This enzyme has been isolated from a variety of sources, including mammalian pancreases

Non-crystallographic symmetry of crystal of neutral phospholipase A_2 from Agkistrodon halys Pallas

Agkistrodotoxin, a neutral phospholipase A2 with high presynaptic neurotoxicity from the venom of Agkistrodon halys Pallas, has been crystallized by hanging drop vapor diffusion method. The crystal belongs to P21 space group with the cell dimensions a = 10.836 nm, b=8.486nm, c = 7.082nm, β=109.87$ showing C2 pseu-do-symmetry. Diffraction data to 0. 26 nm resolution have been collected on a Siemens X-200B area detector. C2 pseu-do-symmetry suggests that there exists a non-crystallographic two-fold axis parallel to crystallographic b axis. Self-rotation function calculation with different integrated radius and resolution ranges using the program POLARRFN yields four stable high peaks corresponding to three more non-crystallographic two-fold axis and one special non-crystal-lographic symmetry. The molecules in the asymmetric unit are suggested to be arranged in a manner of "dimer of dimers" by inference.

Impaired dynamic interaction of axonal endoplasmic reticulum and ribosomes contributes to defective stimulus-response in spinal muscular atrophy

Background:Axonal degeneration and defects in neuromuscular neurotransmission represent a pathological hall-mark in spinal muscular atrophy(SMA)and other forms of motoneuron disease.These pathological changes do not only base on altered axonal and presynaptic architecture,but also on alterations in dynamic movements of organelles and subcellular structures that are not necessarily reflected by static histopathological changes.The dynamic inter-play between the axonal endoplasmic reticulum(ER)and ribosomes is essential for stimulus-induced local translation in motor axons and presynaptic terminals.However,it remains enigmatic whether the ER and ribosome crosstalk is impaired in the presynaptic compartment of motoneurons with Smn(survival of motor neuron)deficiency that could contribute to axonopathy and presynaptic dysfunction in SMA.Methods:Using super-resolution microscopy,proximity ligation assay(PLA)and live imaging of cultured motoneu-rons from a mouse model of SMA,we investigated the dynamics of the axonal ER and ribosome distribution and activation.Results:We observed that the dynamic remodeling of ER was impaired in axon terminals of Smn-deficient motoneu-rons.In addition,in axon terminals of Smn-deficient motoneurons,ribosomes failed to respond to the brain-derived neurotrophic factor stimulation,and did not undergo rapid association with the axonal ER in response to extracellular stimuli.Conclusions:These findings implicate impaired dynamic interplay between the ribosomes and ER in axon terminals of motoneurons as a contributor to the pathophysiology of SMA and possibly also other motoneuron diseases.