Nerve Terminals Research Articles

Acute lipid droplet accumulation induced by the inhibition of the phospholipase DDHD2 does not affect the level, solubility, or phosphoserine-129 status of α-synuclein.

α-Synuclein (αS) is a 140 amino-acid neuronal protein highly enriched in presynaptic nerve terminals. Its progressive accumulation in Lewy bodies and neurites is the hallmark of Parkinson's disease (PD). A growing number of studies highlights a critical interplay between lipid metabolism and αS biology. Some of these works postulate a physical interaction between αS and lipid droplets (LDs), but further clarity is needed, not least because typically exogenous αS and/or heterologous systems have been studied. Here, we investigated the effects of acute LD accumulation on endogenous wild-type αS in primary rat cortical neurons. To induce robust LD accumulation within hours, we inhibited the neuronal triacylglycerol hydrolase DDHD2, a phospholipase, using the compound KLH45. KLH45-induced LD accumulation did not affect total levels, phosphoserine-129 status, or solubility of αS, and no co-localization between LDs and αS was observed under these conditions. These findings suggest that a "second hit" and/or a specific LD lipid composition may be necessary for lipid excess to affect αS homeostasis. Our work thus contributes to the debate on αS structure and lipid interaction.

Sprouting sympathetic fibres release CXCL16 and norepinephrine to synergistically mediate sensory neuronal hyperexcitability in a rodent model of neuropathic pain.

Chronic neuropathic pain generally has a poor response to treatment with conventional drugs. Sympathectomy can alleviate neuropathic pain in some patients, suggesting that abnormal sympathetic-somatosensory signaling interactions might underlie some forms of neuropathic pain. The molecular mechanisms underlying sympathetic-somatosensory interactions in neuropathic pain remain obscure. Lumbar sympathectomy was performed in spared nerve injury (SNI) mice or rats, and the up-down method was used to measure the mechanical paw withdrawal threshold. Dorsal root ganglia (DRG) injection and perfusion were used to deliver virus or drugs. Methylated RNA immunoprecipitation sequencing, RNA-sequencing, and immunoelectron microscopy were used to identify neurotransmitters. We found that sprouting tyrosine hydroxylase-positive sympathetic fibres in DRG mediated the maintenance of mechanical allodynia after SNI (day 28, P<0.001). We further found that SNI significantly increased the N6-methyladenosine level of CXCL16 messenger RNA (day 28, P<0.001), which was attributable to the reduced N6-methyladenosine demethylase fat mass and obesity-associated protein (P=0.002) and increased interaction with YTHDF1 (P=0.013) in the sympathetic ganglion. Enhanced expression of CXCL16 in the sympathetic ganglia can lead to increases release into the DRG and act synergistically with norepinephrine from sympathetic terminals to enhance DRG neuronal excitability. Norepinephrine and CXCL16 co-released from sympathetic nerve terminals in the DRG synergistically contribute to maintenance of neuropathic pain in a rodent model.

HERC1 E3 Ubiquitin Ligase Is Necessary for Autophagy Processes and for the Maintenance and Homeostasis of Vesicles in Motor Nerve Terminals, but Not for Proteasomal Activity.

The ubiquitin proteasome system (UPS) is implicated in protein homeostasis. One of the proteins involved in this system is HERC1 E3 ubiquitin ligase, which was associated with several processes including the normal development and neurotransmission at the neuromuscular junction (NMJ), autophagy in projection neurons, myelination of the peripheral nervous system, among others. The tambaleante (tbl) mouse model carries the spontaneous mutation Gly483Glu substitution in the HERC1 E3 protein. Using this model, we analyzed the implication of HERC1 E3 ubiquitin ligase in the activity of UPS, autophagy, and synaptic homeostasis in brain and muscle tissues. Regarding UPS, no differences were found in its activity nor in the specific gene expression in both brain and muscle tissues from tbl compared with the control littermates. Furthermore, the use of the specific UPS inhibitor (MG-132), did not alter the evoked neurotransmitter release in the levator auris longus (LAL) muscle. Interestingly, the expression of the autophagy-related gene p62 was significantly increased in the muscle of tbl compared to the control littermates. Indeed, impaired evoked neurotransmitter release was observed with the autophagy inhibitor Wortmannin. Finally, altered levels of Clathrin and Synaptophysin were detected in muscle tissues. Altogether, our findings show that HERC1 E3 ubiquitin ligase mutation found in tbl mice alters autophagy and vesicular recycling without affecting proteasomal function.

25-Hydroxycholesterol modulates synaptic vesicle endocytosis at the mouse neuromuscular junction.

Many synaptic vesicles undergo exocytosis in motor nerve terminals during neuromuscular communication. Endocytosis then recovers the synaptic vesicle pool and presynaptic membrane area. The kinetics of endocytosis may shape neuromuscular transmission, determining its long-term reliability. Here, using fluorescent dyes, the time course of endocytosis induced by intense activity of the phrenic nerve was studied at the mouse diaphragm neuromuscular junction. It was found that a significant portion of endocytic events occurs after the end of tetanic stimulation. Pitstop 2, clathrin inhibitor, and more profoundly dynole 34-2, dynamin antagonist, suppressed endocytic FM1-43 dye uptake both during and after tetanus. Furthermore, synaptic vesicles formed in the presence of the endocytic blockers released FM-dye during subsequent evoked exocytosis at a lower rate. 25-Hydroxycholesterol (25HC) is an oxysterol, ubiquitously synthetized from excessive cholesterol. In addition, its production greatly increases by activated macrophages. 25HC accelerated FM-dye endocytosis and its sequential evoked exocytosis, and dynole (but not pitstop) prevented 25HC-mediated enhancement of endocytic FM-dye uptake. The positive effects of 25HC were interfered with chelation of cytosolic Ca2+ with a slow Ca2+ buffer EGTA-AM, Ca2+ antagonist TMB8, and sphingomyelin-hydrolyzing enzyme. In contrast to amphiphilic FM1-43 dye capture, 25HC reduced uptake of hydrophilic high molecular weight markers (labeled dextrans and toxin), which utilize bulk endocytosis to enter into nerve terminals. Thus, synaptic vesicle endocytosis had a relatively slow kinetics following the tetanic activity and can be accelerated by 25HC. The positive effect of 25HC on endocytosis engages a dynamin-dependent pathway, interconnected with cytoplasmic Ca2+ and sphingomyelin integrity.

The Involvement of Glutamate-mGluR5 Signaling in the Development of Vulvar Hypersensitivity.

Provoked vulvodynia (PV) is the leading cause of vulvar pain and dyspareunia. The etiology of PV is multifactorial and remains poorly understood. PV is associated with a history of repeated vulvar inflammation and is often accompanied by sensory neuromodulation as a result of activation of the metabotropic glutamate receptor 5 (mGluR5) in the sensory nerve terminals. Therefore, this study aims to examine the role of glutamate-mGluR5 signaling during the initial inflammatory phase in chronic vulvar pain development in an animal model of PV.Thermal and mechanical vulvar sensitivity was assessed for three weeks following zymosan vulvar challenges. Anxiety-like behavior and locomotor activity were assessed at the end of the experiment. To investigate the role of glutamate mGluR5, the MTEP (mGluR5 antagonist) was injected into the vulva during vulvar inflammation. On the other hand, glutamate or CHPG (mGluR5 agonist) were injected in order to examine the effects of mGluR5 activation. RT-PCR was performed to assess changes in the transcription of genes related to neuroinflammation, neuromodulation, and neuroplasticity in the spinal cord (L6-S3). Zymosan-induced inflammation resulted in a significant thermal and mechanical vulvar hypersensitivity that persisted for over a month after the zymosan injection. However, local treatment with MTEP enhanced the vulvar mechanical and thermal hypersensitivity. On the other hand, activation of the mGluR5 via injection of glutamate or CHPG into the vulva leads to long-lasting vulvar mechanical and thermal hypersensitivity. The activation of the glutamate pathway was found to be accompanied by an increase in the transcription level of genes related to neuroinflammation and neuroplasticity in the sacral spine region. The present findings indicate that vulvar hypersensitivity is mediated by mGluR5 activation during inflammation. Hence, modulation of the mGluR5 pathway during the critical period of inflammation contributes to preventing chronic vulvar pain development. Conversely, activation of the mGluR5 pathway leads to long-lasting mechanical and thermal hypersensitivity.

Maternally activated connections of the ventral lateral septum reveal input from the posterior intralaminar thalamus.

The lateral septum (LS) demonstrates activation in response to pup exposure in mothers, and its lesions eliminate maternal behaviors suggesting it is part of the maternal brain circuitry. This study shows that the density of pup-activated neurons in the ventral subdivision of the LS (LSv) is nearly equivalent to that in the medial preoptic area (MPOA), the major regulatory site of maternal behavior in rat dams. However, when somatosensory inputs including suckling were not allowed, pup-activation was markedly reduced in the LSv. Retrograde tract tracing identified various brain regions potentially influencing LSv neuronal activation through their projections. Among all, anterograde tract tracing confirmed that the posterior intralaminar thalamic nucleus (PIL), implicated in processing touch-related stimuli, targets the pup-activated region of the LSv. Moreover, nerve terminals containing the maternally induced PIL neuropeptide parathyroid hormone 2 (PTH2), were found to form synaptic connections with c-Fos activated LSv neurons using electron microscopy. Confirmation of PTH2 + PIL fibers projecting to LSv was achieved by retrograde tract tracing methods. Furthermore, double retrograde injections revealed that neurons within the PIL can project to both LSv and MPOA, suggesting their simultaneous regulation by PIL input. We also established that septal neurons activated by the pups in the mother are GABAergic and send inhibitory projections to the MPOA and other components of the maternal brain circuitry. This implies that the LSv and MPOA form an interconnected subcircuit in the maternal brain network, which is primarily driven by somatosensory input from the pups via the PIL PTH2 + neurons.

810-nm Photobiomodulation Evokes Glutamate Release in Normal and Rotenone-Dysfunctional Cortical Nerve Terminals by Modulating Mitochondrial Energy Metabolism.

The dysfunction of mitochondria, the primary source of cellular energy and producer of reactive oxygen species (ROS), is associated with brain aging and neurodegenerative diseases. Scientific evidence indicates that light in the visible and near-infrared spectrum can modulate mitochondrial activity, a phenomenon known in medicine as photobiomodulation therapy (PBM-t). The beneficial effects of PBM-t on dementia and neurodegeneration have been reviewed in the literature. However, the molecular mechanisms underlying these findings have yet to be fully elucidated. This study investigates the mechanism behind dose-dependent glutamate release in nerve terminals after irradiation with 810 nm, 1 W for 60 s continuous, 1 cm2, 1 W/cm2, 60 J, 60 J/cm2 (810 nm-1 W) or 810 nm, 0.1 W for 60 s continuous, 1 cm2, 0.1 W/cm2, 6 J, 6 J/cm2 (810 nm-0.1 W), focusing on mitochondrial activities. The results show that PBM modulated the mitochondrial metabolism of cortical nerve terminals and supported a power-dependent increase in oxidative phosphorylation (OxPhos) activity when stimulated with pyruvate plus malate (P/M) or succinate (succ) as respiratory substrates. The PBM-induced increase in OxPhos was sensitive to adding rotenone (Complex I inhibitor) and antimycin A (Complex III inhibitor) when synaptosomes were stimulated with P/M, but only to antimycin A when stimulated with succ. This allowed us to observe that the glutamate efflux, disrupted in the presence of rotenone, was partially restored by PBM due to the increase in the OxPhos pathway led by Complex II. This evidence suggests that PBM, acting on mitochondria, could facilitate physiological communication within the neuron-astrocyte network through vesicular glutamate release, potentially regulating healthy brain function and brain dysfunction.

Comparing adenosine A2A receptor modulation of cannabinoid CB1 receptor-mediated inhibition of GABA and glutamate release in rodent striatal nerve terminals.

In corticostriatal nerve terminals, glutamate release is stimulated by adenosine via A2A receptors (A2ARs) and simultaneously inhibited by endocannabinoids via CB1 receptors (CB1Rs). We previously identified presynaptic A2AR-CB1R heterotetrameric complexes in corticostriatal nerve terminals. We now explored the possible functional interaction between A2ARs and CB1Rs in purified striatal GABAergic nerve terminals (synaptosomes) and compared these findings with those on the release of glutamate. In the striatal synaptosomes of rats and wild-type mice, the synthetic cannabinoid receptor agonist WIN55212-2 (10-1000 nM) attenuated the Ca2+-dependent, high-K+-evoked release of γ-[2,3-3H(N)]-aminobutyric acid ([3H]GABA) and [3H]glutamate. WIN55212-2 did not affect the evoked release of either neurotransmitter under CB1R blockade by AM251 or O-2050 or in CB1R knockout (KO) mice. The A2AR-selective agonist CGS21680 (30 nM) and the A2AR-selective antagonist SCH58261 (100 nM) dampened the inhibitory action of WIN55212-2 in rat synaptosomes. Another A2AR-selective antagonist, ZM241385 (100 nM), abolished the inhibition by WIN55212-2 of the evoked release of both [3H]GABA and [3H]glutamate. Surprisingly, WIN55212-2 also failed to inhibit the evoked release of [3H]GABA but not of [3H]glutamate in A2AR KO mice of both CD-1 and C57BL/6 strains. In rat striatal synaptosomal membranes, the binding of [3H]ZM241385 to A2ARs was not affected by cannabinoids. However, ZM241385 reduced the Bmax while CGS21680 and SCH58261 increased the KD of [3H]SR141716A binding to CB1R, indicating an A2AR-ligand-specific modulation of CB1R function. CB1R Bmax and KD were reduced in A2AR KO mice, whereas A2AR Bmax was smaller in CB1R KO mice. Altogether, our data reveal an intricate interdependence of presynaptic A2ARs and CB1Rs on striatal neuromodulation.

Investigating Complexin-Membrane Interactions Using NMR and Optical Methods.

Complexins are a family of small presynaptic proteins that regulate neurotransmitter release at nerve terminals and are highly conserved in evolution. While direct interactions with SNARE proteins are critical for all complexin functions, binding of their disordered C-terminal domains (CTD) to membranes, especially to synaptic vesicle membranes, is essential for the ability of complexin to inhibit vesicle release. Furthermore, while some complexin CTDs possess an endogenous affinity for membranes, other complexin isoforms are subject to lipidation at their C-termini, which is presumed to confer additional membrane binding. Therefore, an in depth understanding of complexin-membrane interactions is required to elucidate the mechanistic basis for their inhibitory activity. Here we describe protocols for characterizing complexin-membrane interactions using solution state nuclear magnetic resonance (NMR) spectroscopy as well as single molecule total-internal reflection fluorescence (TIRF) methods, along with protocols for generating isotopically labeled samples of unmodified and farnesylated complexins and for characterizing synthetic lipid vesicles using dynamic light scattering (DLS).

Keratinocyte-derived extracellular vesicles in painful diabetic neuropathy.

Painful diabetic neuropathy (PDN) is a challenging complication of diabetes with patients experiencing a painful and burning sensation in their extremities. Existing treatments provide limited relief without addressing the underlying mechanisms of the disease. PDN involves the gradual degeneration of nerve fibers in the skin. Keratinocytes, the most abundant epidermal cell type, are closely positioned to cutaneous nerve terminals, suggesting the possibility of bi-directional communication. Extracellular vesicles are lipid-bilayer encapsulated nanovesicles released from many cell types that mediate cell to cell communication. The role of keratinocyte-derived extracellular vesicles (KDEVs) in influencing signaling between the skin and cutaneous nerve terminals and their contribution to the genesis of PDN has not been explored. In this study, we characterized KDEVs in a well-established high-fat diet mouse model of PDN using primary adult mouse keratinocyte cultures. We obtained highly enriched KDEVs through size-exclusion chromatography and then analyzed their molecular cargo using proteomic analysis and small RNA sequencing. We found significant differences in the protein and microRNA content of high-fat diet KDEVs compared to KDEVs obtained from control mice on a regular diet, including pathways involved in axon guidance and synaptic transmission. Additionally, using an in vivo conditional extracellular vesicle reporter mouse model, we demonstrated that epidermal-originating GFP-tagged KDEVs are retrogradely trafficked into the dorsal root ganglion (DRG) neuron cell bodies. This study presents the first comprehensive isolation and molecular characterization of the KDEV protein and microRNA cargo in RD and HFD mice. Our findings suggest a potential novel communication pathway between keratinocytes and DRG neurons in the skin, which could have implications for PDN.

Adenosine A2A receptor activation is necessary to gate the TrkB-dependent intramuscular nerve sprouting during muscle reinnervation after a nerve crush.

Compelling evidence has demonstrated that rehabilitation through physical exercise, a non-invasive and non-surgical intervention, enhances muscle reinnervation and motor recovery after peripheral nerve injury (PNI) by increasing muscle-derived brain-derived neurotrophic factor (BDNF) expression and triggering TrkB-dependent axonal plasticity. Adenosine has been widely acknowledged to trigger TrkB via A2A receptor (A2AR). Since motor nerve terminals co-express TrkBs and A2ARs and depolarizing conditions increase muscle release of BDNF and adenosine, we examined whether A2ARs activation could recapitulate the functional recovery benefits of intermittent exercise after a nerve crush. Immunohistochemical and in situ proximity ligation assay (isPLA) analyses were used to localize A2ARs and A2A-TrkB heteroreceptor complexes at the neuromuscular level in undenervated animals. The reinnervation process of the soleus muscle was examined in both sedentary and trained animals ten days following a nerve crush injury. The effects of A2A and TrkB interplay on muscle fiber multiple-innervation was assessed using a functional approach. We confirmed that A2A immunoreactivity is mainly localized at the axonal level and provided evidence that A2ARs may form heteroreceptor complexes with TrKb at muscle plasmalemma. The pharmacological activation of either TrkBs or A2ARs mirrored the effect of motor activity on target muscle reinnervation after a nerve crush. Furthermore, the block of A2ARs abolished the effect of TrkBs agonism on nerve endings sprouting. Our results demonstrated that activation of adenosine A2ARs is required to gate the activity-related TrkB-dependent enhancement of axon sprouting during the reinnervation process after a nerve crush. Moreover, our isPLA data suggest that A2ARs can physically interact with TrkBs at the muscle plasmalemma.

A review on recent advancement and pharmacological management of migraine

Modern theories suggest that the primary disorder in migraine takes place within the CNS and that this inspires adjustments in blood vessels within pain-producing intracranial meningeal systems that deliver upward push to headache pain. Migraine is now concept of as a neurovascular ailment it has been proposed that genetic abnormalities may be answerable for changing the response threshold to migraine particular trigger elements in the mind of a migraine compared to a normal individual. the exact nature of the principal disorder that is produced in migraine continues to be not clear and can contain spreading despair-like phenomena and activation of mind stem monoaminergic nuclei that are a part of the primary autonomic, vascular and ache control facilities. it is commonly notion that local vasodilatation of intracranial extracerebral blood vessels and a consequent stimulation of surrounding trigeminal sensory nervous ache pathways is a key mechanism underlying the era of headache ache related to migraine. This activation of the Trigeminovascular device’ is idea to reason the release of vasoactive sensory neuropeptides, mainly CGRP, that boom the ache reaction. The activated trigeminal nerves deliver nociceptive records to significant neurons within the mind stem trigeminal sensory nuclei that in turn relay the ache alerts to better facilities in which headache pain is perceived. it's been hypothesized that these significant neurons may become sensitized as a migraine assault progresses.The ‘triptan’ anti-migraine marketers (e.g. sumatriptan, rizatriptan, zolmitriptan naratriptan) are serotonergic agonists which have been proven to act selectively via inflicting vasoconstriction through 5-HT1B receptors which are expressed in human intracranial arteries and by way of inhibiting nociceptive transmission via an movement at five-HT1D receptors on peripheral trigeminal sensory nerve terminals within the meninges and crucial terminals in brain stem sensory nuclei. these 3 complementary web sites of movement underlie the clinical effectiveness of the 5-HT1B/1D agonists towards migraine headache pain and its related signs and symptoms

Voltage-dependent calcium channels in mammalian motor synapses – triggers and modulators of neuromuscular transmission

The initiation of fast synchronous quantal release of neurotransmitters in central and peripheral synapses is ensured by a local increase in the concentration of Ca2+ ions in the nerve terminals near the Ca2+ sensors of synaptic vesicles in response to depolarization of the presynaptic membrane by an action potential (AP) propagating along the axon. The Ca2+- entry from the outside through presynaptic voltage-dependent Ca2+ channels CaV2.1 or CaV2.2 (P/Q- or N-type) is the main way of forming a dynamic Ca2+ signal that initiates the process of exocytosis of synaptic vesicles in virtually all types of chemical synapses and is capable of inducing the development of certain Ca2+-dependent forms of synaptic plasticity. However, in recent years it has become obvious that the set of sources and the spectrum of presynaptic Ca2+ signals are very diverse. Identification of the ensemble of regulatory Ca2+-entries operating in combination with their corresponding targets, description of their contribution to the mechanisms controlling quantal release of neurotransmitter is a topical area of modern synaptic physiology. Among such additional to the trigger Ca2+-inputs, L-type Ca2+-channels are of particular interest. Their role and activation conditions in neuromuscular junctions (NMJs) are poorly studied and do not provide an unambiguous idea of the place of this Ca2+-entry in the regulation of acetylcholine (ACh) release in vertebrate motor synapses. This review systematizes the currently available research results on the diverse functional role of voltage-gated Ca2+-channels in mammalian NMJs and presynaptic signaling pathways that control these Ca2+-inputs and their participation in the processes of fine-tuning the ACh quantal release.

Irreducible Complexity of &lt;i&gt;Hox&lt;/i&gt; Gene: A Path to the Canonical Function of the Hox Cluster (Review)

The evolution of major taxa is often associated with the emergence of new gene families. In all multicellular animals except sponges and comb jellies, the genomes contain Hox genes, which are crucial regulators of development. The canonical function of Hox genes involves the collinear patterning of body parts in bilateral animals. This general function is implemented through complex, precisely coordinated mechanisms, not all of which are evolutionarily conserved and fully understood. We suggest that the emergence of this regulatory complexity was preceded by a stage of cooperation between more ancient morphogenetic programs or their individual elements. Footprints of these programs may be present in modern animals to execute non-canonical Hox functions. Non-canonical functions of Hox genes are involved in maintaining terminal nerve cell specificity, autophagy, oogenesis, pre-gastrulation embryogenesis, vertical signaling, and a number of general biological processes. These functions are realized by the basic properties of homeodomain protein and could have triggered the evolution of ParaHoxozoa and Nephrozoa subsequently.

The role of the neurovascular unit in vascular cognitive impairment: Current evidence and future perspectives.

Vascular cognitive impairment (VCI) is a progressive cognitive impairment caused by cerebrovascular disease or vascular risk factors. It is the second most common type of cognitive impairment after Alzheimer's disease. The pathogenesis of VCI is complex, and neurovascular unit destruction is one of its important mechanisms. The neurovascular unit (NVU) is responsible for combining blood flow with brain activity and includes endothelial cells, pericytes, astrocytes and many regulatory nerve terminals. The concept of an NVU emphasizes that interactions between different types of cells are essential for maintaining brain homeostasis. A stable NVU is the basis of normal brain function. Therefore, understanding the structure and function of the neurovascular unit and its role in VCI development is crucial for gaining insights into its pathogenesis. This article reviews the structure and function of the neurovascular unit and its contribution to VCI, providing valuable information for early diagnosis and prevention.

Capsaicin-induced Ca2+ overload and ablation of TRPV1-expressing axonal terminals for comfortable tumor immunotherapy.

As a common malignancy symptom, cancer pain significantly affects patients' quality of life. Approximately 60%-90% of patients with advanced cancer experience debilitating pain. Therefore, a comprehensive treatment system that combines cancer pain suppression and tumor treatment could provide significant benefits for these patients. Here, we designed a manganese oxide (MnO2)/Bovine serum albumin (BSA)/polydopamine (PDA) composite nanoplatform internally loaded with capsaicin for cancer pain suppression and immunotherapy. MBD&C nanoparticles (NPs) can ablate tumor-innervated sensory nerve fibers via Transient receptor potential vanilloid 1 (TRPV1) channels, thereby reducing the pain caused by various inflammatory mediators. The ablation of TRPV1+ nerve terminals can also decrease the secretion of calcitonin gene-related peptide (CGRP) and substance P (SP) in sensory nerve fibers, thus reducing the tumor pain and inhibit tumor progression. MBD&C can promote calcium influx by activating overexpressed TRPV1 channels on the tumor membrane surface, thereby achieving cancer immunotherapy induced by endogenous Ca2+ overloading. In addition, MnO2 NPs can alleviate tumor hypoxia and mitigate the immunosuppressive tumor microenvironment (TME). Ultimately, this treatment system with dual capabilities of inhibiting tumor growth and relieving cancer pain makes comfortable tumor therapy feasible and paves the way for the development of patient-centered approaches to cancer treatment in the future.

AMINO-GRAFTED MESOPOROUS SILICA NANOPARTICLES: ASSESSMENT OF NEUROMODULATORY, MEMBRANOTROPIC AND ANTIOXIDANT PROPERTIES IN CORTEX NERVE TERMINALS

Aim. In biomedical applications, silica nanoparticles are promising for controlled drug delivery. Also, from an environmental point of view, silica accounts for the most significant part of the mass of air pollution, particularly matter components, especially during sand dust storms. Methods. Amino-grafted mesoporous silica nanoparticles (MSN-NH2) were synthesized by means of co-condensation of tetraethoxysilane and 3-aminopropyltriethoxysilane and characterized using TEM, IR-spectroscopy, and powder X-ray diffraction. Neuromodulatory and related properties of MSN-NH2 were evaluated using rat cortex nerve terminals (synaptosomes). Results. MSN-NH2 did not influence the extracellular synaptosomal level of excitatory neurotransmitter L-[14C]glutamate and so did not cause excitotoxicity. In fluorescence measurements, MSN-NH2 depolarised the synaptosomal membrane and demonstrated weak antioxidant properties, decreasing the spontaneous generation of reactive oxygen species, whereas MSN-NH2 did not alter H2O2 in nerve terminals. The model of Cd2+/Pb2+/Hg2+-induced excitotoxicity was used to assess the capability of MSN-NH2 to adsorb xenobiotic heavy metals. MSN-NH2 did not modulate the Cd2+/Pb2+/Hg2+-induced increase in the extracellular synaptosomal level of L-[14C]glutamate. Conclusion. MSN-NH2 did not demonstrate excitotoxic signs, had weak antioxidant properties, and was biocompatible. MSN-NH2 did not mitigate the excitotoxic effects of xenobiotic heavy metals and did not adsorb these metals in biological systems.

Direct Modulation of CRH Nerve Terminal Function by Noradrenaline and Corticosterone.

Nerve terminals are the final point of regulation before neurosecretion. As such, neuromodulators acting on nerve terminals can exert significant influence on neural signaling. Hypothalamic corticotropin-releasing hormone (CRH) neurons send axonal projections to the median eminence where CRH is secreted to stimulate the hypothalamic-pituitary-adrenal (HPA) axis. Noradrenaline and corticosterone are two of the most important neuromodulators of HPA axis function; noradrenaline excites CRH neurons and corticosterone inhibits CRH neurons by negative feedback. Here, we used GCaMP6f Ca2+ imaging and measurement of nerve terminal CRH secretion using sniffer cells to determine whether these neuromodulators act directly on CRH nerve terminals in male mice. Contrary to expectations, noradrenaline inhibited action potential-dependent Ca2+ elevations in CRH nerve terminals and suppressed evoked CRH secretion. This inhibitory effect was blocked by α2-adrenoreceptor antagonism. Corticosterone also suppressed evoked CRH peptide secretion from nerve terminals, independent of action potential-dependent Ca2+ levels. This inhibition was prevented by the glucocorticoid receptor antagonist, RU486, and indicates that CRH nerve terminals may be a site of fast glucocorticoid negative feedback. Together these findings establish median eminence nerve terminals as a key site for regulation of the HPA axis.

Anatomical Variations of the Brachial Plexus: A Cadaveric Study

Objective: Variations of the brachial plexus are a lot commoner than presumed and a better understanding of such variations are of crucial importance to achieve successful results in surgical procedures. The aim of our study was to describe the anatomical variations of the brachial plexus in Sri Lankan adult cadavers. Methods: Bilateral upper limbs of cadavers used for routine dissection from January 2023 to September 2024, were examined and the trunks, cords and terminal nerves were described. Images were taken and variations were carefully noted and recorded. Results: Sixty brachial plexuses in 30 cadavers (19 males and 11 females) with a mean age at death of 70.75 years (SD=10.31) were observed. Prevalence of variations was 40%. We report 7 (11.6%) prefixed and 1 postfixed (1.6%) brachial plexuses, variant connections between lateral and medial cords (5 – 8.3%), variant connection between lateral cord and median root of median nerve1(1 - 1.6%), rare variant of only two cords (posterior and combined medial lateral to form an anterior cord), absent musculocutaneous nerve (2 - 2.3%) and musculocutaneous nerve giving a branch to the median nerve (3 – 5%). Conclusion: Variations of the brachial plexus are quite common and highly variable and therefore require constant reporting to provide medical personal with information that could prevent iatrogenic injury and help in proper diagnosis of cases.

Radiofrequency Ablation of Terminal Sensory Articular Nerves Before Arthroscopic Rotator Cuff Repair Surgery Improved Early Postoperative Functional Outcomes: A Pilot Study With 3 Months Follow-up.

Chronic shoulder pain caused by a rotator cuff tear is commonly treated with arthroscopic rotator cuff repair surgery (ARCR). However, ARCR may be associated with moderate-to-severe postoperative pain, and poorly controlled pain can result in delayed functional recovery and the development of frozen shoulder. Terminal sensory articular nerve radiofrequency ablation (RFA) has been shown to be clinically effective in patients with severe refractory shoulder pain from multiple etiologies. We aimed to investigate whether preoperative RFA would improve the postoperative pain and functional outcomes after ARCR. In this prospective pilot study, participants were randomized to receive fluoroscopic-guided terminal sensory articular nerve cooled RFA (CRFA) (supraspinatus nerve, axillary nerve, lateral pectoral nerve) 1-5 days prior to elective ARCR as an intervention group compared to ARCR without prior RFA as a control group. Constant score (CS), American Shoulder and Elbow Surgeon score (ASES), and Pain numerical rating score (NRS) were assessed at 1, 2, 3, 4, 5, and 6 weeks and 3 months following ARCR. Twenty-one participants were enrolled in this study, including 11 in the control group and 10 in the cooled RFA group. The cooled RFA group showed statistically significantly better CS and ASES both at 6 weeks and 3 months. The two groups showed no differences in pain outcomes at all time points. No intervention-related complications were noted. Cooled RFA of the terminal sensory articular branches of the supraspinatus, axillary, and lateral pectoral nerves performed 1-5 days prior to elective ARCR as part of a multimodal postoperative pain management regimen can improve functional outcomes as early as 6 weeks. III.