Parkinson's disease (PD) is a neurodegenerative disorder characterized by the aggregation of α-synuclein (α-syn) and dysregulated synaptic vesicle (SV) recycling. Emerging evidence suggests that ferroptosis is the target of PD therapy. However, the identification of effective anti-ferroptosis treatments remains elusive. This study explores the therapeutic potential of low-intensity ultrasound (US) in modulating SV recycling and anti-ferroptosis in cellular and animal models of PD. We demonstrate that optimized US stimulation (610 kHz, 0.2 W/cm²) activates Piezo1 channel-mediated fast endophilin-mediated endocytosis, which promotes SV recycling and synaptic function, presenting with increased frequency and amplitude of both spontaneous excitatory synaptic currents and miniature excitatory postsynaptic currents. Repaired SV recycling in turn reduces the accumulation of α-syn expression and ferroptotic cell death. These findings support the potential of noninvasive ultrasonic neuromodulation as a therapeutic strategy for PD and lead to meaningful health outcomes for the aging population.
Animals ; Ferroptosis/physiology* ; Synaptic Vesicles/metabolism* ; Dopaminergic Neurons/metabolism* ; Ion Channels/metabolism* ; Mice ; Ultrasonic Waves ; Humans ; Male ; Mice, Inbred C57BL ; Endocytosis/physiology* ; alpha-Synuclein/metabolism*

OBJECTIVETo investigate acrylamide (ACR)-induced subacute neurotoxic effects on the central nervous system (CNS) at the synapse level in rats.

METHODSThirty-six Sprague Dawley (SD) rats were randomized into three groups, (1) a 30 mg/kg ACR-treated group, (2) a 50 mg/kg ACR-treated group, and (3) a normal saline (NS)-treated control group. Body weight and neurological changes were recorded each day. At the end of the test, cerebral cortex and cerebellum tissues were harvested and viewed using light and electron microscopy. Additionally, the expression of Synapsin I and P-Synapsin I in the cerebral cortex and cerebellum were investigated.

RESULTSThe 50 mg/kg ACR-treated rats showed a significant reduction in body weight compared with untreated individuals (P < 0.05). Rats exposed to ACR showed a significant increase in gait scores compared with the NS control group (P < 0.05). Histological examination indicated neuronal structural damage in the 50 mg/kg ACR treatment group. The active zone distance (AZD) and the nearest neighbor distance (NND) of synaptic vesicles in the cerebral cortex and cerebellum were increased in both the 30 mg/kg and 50 mg/kg ACR treatment groups. The ratio of the distribution of synaptic vesicles in the readily releasable pool (RRP) was decreased. Furthermore, the expression levels of Synapsin I and P-Synapsin I in the cerebral cortex and cerebellum were decreased in both the 30 mg/kg and 50 mg/kg ACR treatment groups.

CONCLUSIONSubacute ACR exposure contributes to neuropathy in the rat CNS. Functional damage of synaptic proteins and vesicles may be a mechanism of ACR neurotoxicity.

Acrylamide ; toxicity ; Animals ; Cerebellum ; cytology ; drug effects ; Cerebral Cortex ; cytology ; drug effects ; Drug Administration Schedule ; Gait ; Gene Expression Regulation ; drug effects ; Male ; Neurons ; drug effects ; Neurotoxicity Syndromes ; pathology ; Rats ; Rats, Sprague-Dawley ; Synapses ; drug effects ; Synapsins ; genetics ; metabolism ; Synaptic Vesicles ; drug effects ; physiology ; Weight Loss ; drug effects

Synaptic vesicle protein 2A (SV2A) involvement has been reported in the animal models of epilepsy and in human intractable epilepsy. The difference between pharmacosensitive epilepsy and pharmacoresistant epilepsy remains poorly understood. The present study aimed to observe the hippocampus SV2A protein expression in amygdale-kindling pharmacoresistant epileptic rats. The pharmacosensitive epileptic rats served as control. Amygdaloid-kindling model of epilepsy was established in 100 healthy adult male Sprague-Dawley rats. The kindled rat model of epilepsy was used to select pharmacoresistance by testing their seizure response to phenytoin and phenobarbital. The selected pharmacoresistant rats were assigned to a pharmacoresistant epileptic group (PRE group). Another 12 pharmacosensitive epileptic rats (PSE group) served as control. Immunohistochemistry, real-time PCR and Western blotting were used to determine SV2A expression in the hippocampus tissue samples from both the PRE and the PSE rats. Immunohistochemistry staining showed that SV2A was mainly accumulated in the cytoplasm of the neurons, as well as along their dendrites throughout all subfields of the hippocampus. Immunoreactive staining level of SV2A-positive cells was 0.483 ± 0.304 in the PRE group and 0.866 ± 0.090 in the PSE group (P < 0.05). Real-time PCR analysis demonstrated that 2(-ΔΔCt) value of SV2A mRNA was 0.30 ± 0.43 in the PRE group and 0.76 ± 0.18 in the PSE group (P < 0.05). Western blotting analysis obtained the similar findings (0.27 ± 0.21 versus 1.12 ± 0.21, P < 0.05). PRE rats displayed a significant decrease of SV2A in the brain. SV2A may be associated with the pathogenesis of intractable epilepsy of the amygdaloid-kindling rats.
Amygdala ; drug effects ; metabolism ; physiopathology ; Animals ; Anticonvulsants ; pharmacology ; Disease Models, Animal ; Drug Resistance ; Electric Stimulation ; Epilepsy ; drug therapy ; genetics ; metabolism ; pathology ; Gene Expression Regulation ; Hippocampus ; drug effects ; metabolism ; physiopathology ; Kindling, Neurologic ; drug effects ; genetics ; metabolism ; pathology ; Male ; Membrane Glycoproteins ; genetics ; metabolism ; Nerve Tissue Proteins ; genetics ; metabolism ; Phenobarbital ; pharmacology ; Phenytoin ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Synaptic Transmission ; Synaptic Vesicles ; drug effects ; metabolism ; pathology

Motor units comprise a motoneuron and the muscle fibers it innervates. Neuromuscular transmission is tightly regulated to match the activity of individual motor units. Activity-dependent release of neuromodulators at the neuromuscular junction (NMJ) determines the efficacy of transmission. The neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) are produced by motoneurons and muscle fibers, and their release by skeletal muscle is regulated by muscle activity. BDNF and NT-4 enhance both spontaneous and evoked synaptic transmission at NMJs via activation of the tyrosine kinase receptor B (TrkB). Improvements in neuromuscular transmission may result from increased release of synaptic vesicles, either by presynaptic alterations in Ca(2+) transients or facilitated vesicular exocytosis. In fact, BDNF potentiates intracellular Ca(2+) release presynaptically and BDNF-induced TrkB activation also results in phosphorylation of synapsin I via mitogen activated protein kinase, which increases the number of synaptic vesicles available for release. Neurotrophins may also regulate synaptic transmission at the NMJ by increasing local release of neuregulin or other nerve-derived modulators. We review recent studies on the regulation of neuromuscular transmission, the motor unit-specific properties of NMJs and the effects of neurotrophins on synaptic efficacy at the NMJ.
Animals ; Brain-Derived Neurotrophic Factor ; physiology ; Calcium ; metabolism ; Humans ; Nerve Growth Factors ; physiology ; Neuromuscular Junction ; physiology ; Neuronal Plasticity ; Receptor, trkB ; metabolism ; Synapses ; metabolism ; Synapsins ; metabolism ; Synaptic Vesicles

The release of neurotransmitter is regulated in the processes of membrane docking and membrane fusion between synaptic vesicles and presynaptic plasma membranes. Synaptic vesicles contain a diverse set of proteins that participate in these processes. Small GTP-binding proteins exist in the synaptic vesicles and are suggested to play roles for the regulation of neurotransmitter release. We have examined a possible role of GTP-binding proteins in the regulation of protein phosphorylation in the synaptic vesicles. GTPgammaS stimulated the phosphorylation of 46 kappa Da protein (p46) with pI value of 5.0-5.2, but GDPbetaS did not. The p46 was identified as protein interacting with C-kinase 1 (PICK-1) by MALDI-TOF mass spectroscopy analysis, and anti-PICK-1 antibody recognized the p46 spot on 2-dimensional gel electrophoresis. Rab guanine nucleotide dissociation inhibitor (RabGDI), which dissociates Rab proteins from SVs, did not affect phosphorylation of p46. Ca2+/ calmodulin (CaM), which causes the small GTP- binding proteins like Rab3A and RalA to dissociate from the membranes and stimulates CaM- dependnet protein kinase(s) and phosphatase, strongly stimulate the phosphorylation of p46 in the presence of cyclosporin A and cyclophylin. However, RhoGDI, which dissociates Rho proteins from membranes, reduced the phosphorylation of p46 to the extent of about 50%. These results support that p46 was PICK-1, and its phosphorylation was stimulated by GTP and Ca2+/CaM directly or indirectly through GTP-binding protein(s) and Ca2+/CaM effector protein(s). The phosphorylation of p46 (PICK-1) by GTP and Ca2+/CaM may be important for the regulation of transporters and neurosecretion.
Animals ; Calcium/*metabolism ; Calmodulin/*metabolism ; Carrier Proteins/*chemistry/*metabolism ; Guanine Nucleotide Dissociation Inhibitors/metabolism ; Guanosine Triphosphate/metabolism/*pharmacology ; Molecular Weight ; Monomeric GTP-Binding Proteins/metabolism ; Phosphorylation/drug effects ; Rats ; Recombinant Fusion Proteins/*chemistry/*metabolism ; Synaptic Membranes/chemistry/drug effects/*metabolism ; Synaptic Vesicles/chemistry/drug effects/*metabolism