Search Results (102)

Background/Objectives: One of the neurotoxic components from the sea trumpet polyps, Protopalythoa variabilis (Cnidaria, Anthozoa), is a 26-residue, V-shape helical peptide (PpVα). Its synthetic versions, i.e., the linear, the single-disulfide-bonded analog, and the chimeric peptide with a 6-residue stretch of the N-terminal native homologous peptide covalently linked to the linear sequence, were investigated for their activity on ion channels responsible for cellular excitability and synaptic transmission. Methods: Molecular docking analyses and dynamic simulations focused on the ability of PpVα peptides to bind ion channels selectively through interaction with critical residues at their binding sites. Results: Electrophysiological studies using the patch clamp technique with sympathetic bovine chromaffin cells from the adrenal medulla confirmed that PpVα analogs can block both sodium and calcium currents, which are responsible for initiating and propagating action potentials, respectively, and for neurotransmitter release. Additionally, the peptides displayed neuroprotective effects, attenuating cellular damage induced by veratridine, which interferes with sodium channel activity, and by oligomycin and rotenone (O/R), which affect mitochondrial function. Conclusions: The block of calcium and sodium channels and the neuroprotective effects against oxidative stress make the PpVα peptide scaffold an attractive template for developing agents that has significant clinical potential in several areas, such as the treatment of neurological diseases (epilepsy, multiple sclerosis, and neurodegenerative diseases), neuroprotection in acute events (stroke and traumatic brain or spinal cord injuries), the management of neuropathic pain, the prevention of ischemic damage, and psychiatric disorders (anxiety and bipolar disorder). Full article

Background: Burning Mouth Syndrome (BMS) is a nociplastic pain condition characterized by altered central nervous system pain processing, significantly impacting patient quality of life. Pharmacological management often involves amitriptyline (monotherapy) and aripiprazole (for refractory cases) in Japan. However, the therapeutic efficacy of these drugs in BMS frequently exhibits a non-sigmoid (U-shaped or bell-shaped) dose–response relationship, indicating a clinically effective dose that is often considerably lower than those used for their primary indications and challenging conventional pharmacological assumptions. Method: This paper synthesizes existing pharmacological knowledge to elucidate the mechanisms underlying the non-dose-dependent actions of amitriptyline and aripiprazole in BMS. It focuses on their specific interactions with key neurotransmitter systems and receptors, particularly N-methyl-D-aspartate (NMDA) receptors and dopamine D2 receptors, to explain the observed non-linear dose–response and the importance of identifying a personalized therapeutic window. Result: Amitriptyline demonstrates efficacy in BMS at low doses (e.g., 25 mg), primarily through its action as an NMDA receptor antagonist via calcium-dependent desensitization and open-channel block, addressing central sensitization. Its effects are distinct from its antidepressant actions, and the “serotonin paradox” highlights the complexity of serotonin’s role in pain. Aripiprazole, utilized for refractory BMS, acts as a dopamine D2 receptor partial agonist, leading to a non-linear dose–response where sustained therapeutic effect is observed at specific low doses (e.g., 1.7–1.8 mg/day). This non-linearity is attributed to partial agonism, alongside interactions with serotonin 5-HT1A and 5-HT2A receptors. The general non-dose-dependency for both drugs is further explained by phenomena such as multiple binding sites with differing affinities, receptor desensitization/downregulation, activation of counter-regulatory mechanisms, and hormesis. Discussion: The observed non-linear dose–response curves for amitriptyline and aripiprazole in BMS underscore the inadequacy of a “one-size-fits-all” treatment approach. This necessitates a shift towards personalized medicine, which considers individual patient factors including pharmacogenomics, comorbidities, age, organ function, and psychological/social profiles. The true “personalized therapeutic window” is a balance between achieving significant pain relief and minimizing adverse effects, emphasizing careful titration and patient-centered care. Conclusions: The pharmacological actions of amitriptyline and aripiprazole in BMS are not linearly dose-dependent, but rather exhibit a personalized therapeutic window driven by complex interactions with NMDA and D2 receptors and adaptive physiological responses. This intricate pharmacological landscape mandates a personalized medicine approach to optimize treatment outcomes, improve patient adherence, and enhance the quality of life for individuals suffering from this challenging nociplastic pain condition. Full article

Although opioids are effective in treating pain, they cause serious side effects. The use of regional anesthesia, although effective in the perioperative period, may not be suitable if mobility and lack of numbness is desired. Hence, there is a clear need for novel pain therapies. Low-voltage activated (T-type) calcium channels (Ca_V3.2 isoform) could be a promising therapeutic target for the development of novel pain therapies. Indeed, our published findings suggest that novel neuroactive steroid (NAS) analogs that modulate the activity of Ca_V3.2 channels have unique anti-nociceptive properties. However, the concern with current NASs appears to be their hypnotic/sedative properties, thus potentially hindering the future development of NASs for novel pain therapies. Hence, we developed a new line of NASs that are effective blockers of neuronal Ca_V3.2 channels in pain pathways while having more favorable pharmacodynamic properties, i.e., lack of sedative/hypnotic side effects. We present two promising novel analogs of NASs—B372 ((3β,5α,17β)-3-Hydroxyandrostan-17-carbonitrile) and YX23 ((3β,5α,17β)-3-Methoxyestran-17-ol). Using an in vitro approach, we show that B372 and YX23 are effective in blocking Ca_V3.2 channels. Using an in vivo approach, we show that they are effective anti-nociceptives in wild-type but not Ca_V3.2 knock-out mice. Importantly, we show that they lack sedative/hypnotic effects. Full article

We used molecular docking as a computational tool to predict the binding affinities and interactions of quercetin 3-O-malonylglucoside (Q3MG) with vascular target proteins. First, the proteins 1M9M (human endothelial nitric oxide synthase; eNOS) and 6ND0 (human large-conductance voltage- and calcium-activated K⁺ channels; BK_Ca) were downloaded from the Protein Data Bank and submitted to molecular docking studies, revealing Q3MG binding affinities for both proteins. The vascular effect of Q3MG was investigated in the perfused mesenteric vascular beds (MVBs) of spontaneously hypertensive rats. In preparations with functional endothelium, Q3MG dose-dependently reduced the perfusion pressure in MVBs. Removal of the endothelium or inhibition of the nitric oxide synthase enzyme by L-NAME blocked the vasodilation induced by Q3MG. Perfusion with a physiological solution containing high KCl or the use of a non-selective blocker of K⁺ channels, as well as perfusion with iberiotoxin, completely abolished the vasodilatory effects of Q3MG. The data obtained suggest that the vascular effects of Q3MG involve the activation of the NO/cGMP pathway followed by the opening of BK_Ca. Full article

Background/Objectives: Haloxylon griffithii is a medicinal plant possessing therapeutic effects in disorders associated with the gastrointestinal (GIT) system. This research aims to study the pharmacological activity of Haloxylon griffithii in a multidimensional manner, involving phytochemistry screening and in vitro and in vivo experiments. Methods: The whole dried plant was extracted with 80% methanol and further fractionation using solvents of increasing polarity. GC-MS analysis was performed on the crude extract to discover volatile compounds. The spasmolytic/spasmogenic effect was assessed in isolated rabbit jejunum using spontaneous and K⁺-induced contractions, as well as contractions induced by increasing concentrations of calcium ions in depolarized tissue. Antidiarrheal activity was evaluated in Swiss albino rats/mice (n = 6/group) using castor oil-induced diarrhea and peristaltic index models. In silico ADMET screening was conducted via SwissADME and pkCSM. Results: The GC-MS profiling of H. griffithii revealed the presence of 59 phytochemicals and a rare azulene derivative and constituents, including α-santonin and hexadecanoic acid esters, with favorable pharmacokinetic profiles, as predicted using SwissADME and pkCSM computational tools. The in vitro and in vivo experiments revealed the significant calcium channel blocking activity in non-polar fractions (n-hexane and ethyl acetate), while the polar extracts (ethanolic, aqueous) exhibited cholinergic effects, indicating a dual mode of action. Conclusions: This was a first-time demonstration of both antidiarrheal and smooth muscle-relaxant activity in H. griffithii, supported by GC-MS profiling and pharmacological assay. The findings lend scientific credibility to the traditional use of the plant in community healthcare, while also reinforcing the need for further pharmacological and clinical studies to explore its potential in drug development. Full article

Background: Transient receptor potential vanilloid subtype 4 (TRPV4) is a Ca²⁺-permeable non-selective cation channel that is involved in the development of cough hypersensitivity. Purinergic 2 receptors (P2X) belong to a class of adenosine triphosphate (ATP)-gated non-selective cation channels that also play an important role in cough hypersensitivity. Nevertheless, little is known about the interaction between them for cough hypersensitivity. The present study was designed to clarify the roles of TRPV4 and ATP-P2X receptors in cough hypersensitivity, and to explore the possible involvement of ATP-P2X receptors in the development of cough hypersensitivity mediated by TRPV4. Design and Method: This study aims to establish a guinea pig model of citric acid-induced enhanced cough to confirm the effects of the TRPV4-mediated purinergic signaling pathway on cough sensitivity by testing the number of coughs, the release of ATP, and the expressions of P2X and TRPV4 receptors in the tracheal carina and vagal ganglion; recording the activity of cellular currents with the whole-cell patch clamp technique; and detecting changes in intracellular calcium flow in the vagus nerve cells. Results: The number of coughs in the TRPV4 agonist GSK1016790A-treated control group was elevated compared with that in the control group, whereas the number of coughs in the TRPV4 antagonist HC067047-treated model group was significantly reduced compared with that in the chronic cough group. When the individuals in the chronic cough group were treated with A317491, PSB12062, and A804598 (P2X3,4,7 antagonists), the number of coughs was significantly decreased. This suggests that TRPV4 and P2X3, P2X4, and P2X7 receptors have an effect on cough hyper-responsiveness in guinea pigs with chronic cough. Enzyme-linked immunosorbent assay results suggested that TRPV4 antagonist and P2X3,4,7 antagonist could differentially reduce the levels of inflammatory factor SP and CGRP in alveolar lavage fluid, and TRPV4 antagonist could reduce the ATP content in the alveolar lavage fluid of guinea pigs in the model. Western blot and immunohistochemistry results showed that, in the tracheal carina and vagal ganglion, the TRPV4 and P2X3,4,7 expression was elevated in the chronic cough group compared with the control group, and could be significantly inhibited by TRPV4 antagonist. Vagus ganglion neurons were isolated, cultured, identified, and subjected to whole-cell membrane clamp assay. When ATP was given extracellularly, a significant inward current was recorded in the examined cells of individuals in the chronic cough and control groups, and the inward current induced by ATP was higher in the chronic cough group relative to the control group. This inward current (I_ATP) was differentially blocked by P2X3, P2X4, and P2X7 antagonists. Further studies revealed that TRPV4 agonists potentiated ATP-activated currents, and the potentiated currents could still be inhibited by P2X3, P2X4, and P2X7 receptor antagonists, whereas TRPV4 inhibitors partially blocked ATP-activated currents. It is suggested that TRPV4 affects P2X3, P2X4, and P2X7 receptor-mediated ATP-activated currents. Calcium imaging also showed that TRPV4 agonists induced different degrees of calcium inward currents in the vagal neurons of the chronic cough and the control group, and the calcium inward currents were more significant in the model group. Conclusions: The TRPV4-mediated purinergic signaling pathway was identified to be involved in the development of cough hypersensitivity in guinea pigs with chronic cough; i.e., TRPV4 can lead to the release of airway epithelial ATP, which can stimulate P2X receptors on the cough receptor, and further activate the sensory afferent nerves in the peripheral airway, leading to increased cough sensitivity. Full article

The healing process involves cell migration, which is sustained by an electrical potential difference that emerges between the edges of skin wounds and the center of the wound. The electrical potential in cells’ membranes is responsible for their migration in an electric field. The differences in the transmembrane electrochemical gradient generate this potential. The concomitant blockade of potassium and calcium channels by amiodarone at a medium dosage favored wound healing, but the effect was less intense than in the case of the selective blocking of potassium channels. According to this suggestion, blocking calcium channels might have a partial effect on blocking potassium channels. Given that nimodipine inhibits both L-type and T-type calcium channels, we aimed to investigate which of these calcium channels are involved in wound healing. Hence, we performed an experimental study in which nimodipine was used in three concentrations: 200 nM, which blocks only L-type calcium channels, 1000 nM, which blocks both L-type and T-type calcium channels, and 10,000 nM, which blocks calcium channels and activates CB1 cannabinoid receptors, respectively. The present research is a continuation of previous studies conducted by us, aimed to propose new perspectives on wound treatment. In conclusion, the blocking of calcium channels favored wound healing under our experimental conditions, but this happened only by simultaneously blocking the L-type and T-type calcium channels, because only the medium nimodipine concentration had a statistically significant effect. Full article

Background: Apigenin (4′,5,7-trihydroxyflavone), a flavonoid with potential cardiovascular benefits, has unclear mechanisms of action. This study investigates its effects on vascular function in Spontaneously Hypertensive Rats (SHRs). Methods: Mesenteric vascular beds (MVBs) were isolated from SHRs and perfused with increasing doses of apigenin after pre-contraction with phenylephrine. To explore the mechanisms, different MVBs were pre-perfused with antagonists and inhibitors, including indomethacin, L-NAME, and potassium channel blockers (tetraethylammonium, a non-specific potassium channel blocker; glibenclamide, an ATP-sensitive potassium channel blocker; 4-aminopyridine, a voltage-gated potassium channel blocker; charybdotoxin a selective intermediate-conductance calcium-activated potassium channel blocker; and apamin, a selective small-conductance calcium-activated potassium channel blocker). Results: Apigenin induced a dose-dependent reduction in perfusion pressure in MVBs with intact endothelium, an effect abolished by endothelium removal. L-NAME reduced apigenin-induced vasodilation by approximately 40%. The vasodilatory effect was blocked by potassium chloride and tetraethylammonium. The inhibition of small and intermediate calcium-activated potassium channels with charybdotoxin and apamin reduced apigenin-induced vasodilation by 50%, and a combination of these blockers with L-NAME completely inhibited the effect. Conclusions: Apigenin promotes vasodilation in resistance arteries through endothelial nitric oxide and calcium-activated potassium channels. These findings suggest that apigenin could have therapeutic potential in cardiovascular disease, warranting further clinical research. Full article

Cystic fibrosis (CF) is a genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, resulting in defective chloride ion channels. This leads to thick, dehydrated mucus that severely disrupts mucociliary clearance in the respiratory system and triggers infection that eventually is the cause of death of CF patients. Current therapeutic strategies primarily focus on restoring CFTR function, blocking epithelial sodium channels to prevent mucus dehydration, or directly targeting mucus to reduce its viscosity. Among the ion channels expressed in ciliated bronchial epithelial cells, the transient receptor potential vanilloid 4 (TRPV4) channel emerges as a significant channel in CF pathogenesis. Activation of TRPV4 channels affects the regulation of airway surface liquid by modulating sodium absorption and intracellular calcium levels, which indirectly influences CFTR activity. TRPV4 is also involved in the regulatory volume decrease (RVD) process and enhances inflammatory responses in CF patients. Here, we combine current findings on TRPV4 channel modulation as a promising therapeutic approach for CF. Although limited studies have directly explored TRPV4 in CF, emerging evidence indicates that TRPV4 activation can significantly impact key pathological processes in the disease. Further investigation into TRPV4 modulators could lead to innovative treatments that alleviate severe respiratory complications and improve outcomes for CF patients. Full article

Neurotransmission is critical for brain function, allowing neurons to communicate through neurotransmitters and neuropeptides. RVD-hemopressin (RVD-Hp), a novel peptide identified in noradrenergic neurons, modulates cannabinoid receptors CB1 and CB2. Unlike hemopressin (Hp), which induces anxiogenic behaviors via transient receptor potential vanilloid 1 (TRPV1) activation, RVD-Hp counteracts these effects, suggesting that it may block TRPV1. This study investigates RVD-Hp’s role as a TRPV1 channel blocker using HEK293 cells expressing TRPV1-GFP. Calcium imaging and patch-clamp recordings demonstrated that RVD-Hp reduces TRPV1-mediated calcium influx and TRPV1 ion currents. Molecular docking and dynamics simulations indicated that RVD-Hp interacts with TRPV1’s selectivity filter, forming stable hydrogen bonds and van der Waals contacts, thus preventing ion permeation. These findings highlight RVD-Hp’s potential as a therapeutic agent for conditions involving TRPV1 activation, such as pain and anxiety. Full article

The conjunctiva has immune-responsive properties to protect the eye from infections. Its innate immune system reacts against external pathogens, such as fungi. The complement factor C5a is an important contributor to the initial immune response. It is known that activation of transient-receptor-potential-vanilloid 1 (TRPV1) and TRP-melastatin 8 (TRPM8) channels is involved in different immune reactions and inflammation in the human body. The aim of this study was to determine if C5a and mucor racemosus e voluminae cellulae (MR) modulate Ca²⁺-signaling through changes in TRPs activity in human conjunctival epithelial cells (HCjECs). Furthermore, crosstalk was examined between C5a and MR in mediating calcium regulation. Intracellular Ca²⁺-concentration ([Ca²⁺]_i) was measured by fluorescence calcium imaging, and whole-cell currents were recorded using the planar-patch-clamp technique. MR was used as a purified extract. Application of C5a (0.05–50 ng/mL) increased both [Ca²⁺]_i and whole-cell currents, which were suppressed by either the TRPV1-blocker AMG 9810 or the TRPM8-blocker AMTB (both 20 µM). The N-terminal peptide C5L2p (20–50 ng/mL) blocked rises in [Ca²⁺]_i induced by C5a. Moreover, the MR-induced rise in Ca²⁺-influx was suppressed by AMG 9810 and AMTB, as well as 0.05 ng/mL C5a. In conclusion, crosstalk between C5a and MR controls human conjunctival cell function through modulating interactions between TRPV1 and TRPM8 channel activity. Full article

Antispasmodic agents are crucial in managing gastrointestinal motility disorders by modulating muscle contractions and reducing symptoms like cramping and diarrhea. This study investigated the antispasmodic potential of different coffee bean extracts, including light coffee (LC), medium coffee (MC), and dark coffee (DC), on ileum contractions induced by potassium chloride (KCl), and elucidated their mechanisms of action using in vitro isolated tissue techniques. The results demonstrated that all coffee extracts reduced spontaneous contractions of rat ileum tissue in a dose-dependent manner. Among these, LC showed the most significant reduction in ileum contractions, particularly at higher concentrations. The key findings reveal that LC at 5 mg/mL significantly reduced CaCl₂-induced contractions in isolated rat ileum tissue, indicating that LC may inhibit calcium influx or interfere with calcium signaling pathways. The presence of nifedipine, propranolol, and N-nitro-L-arginine methyl ester (L-NAME) have been confirmed in their involvement; they block calcium influx and calcium channels and activate β-adrenergic pathways as part of LC’s mechanism of action. The presence of their active compounds, particularly chlorogenic acid and caffeine, likely contributes to the observed antispasmodic effects. These findings suggest that LC exerts its antispasmodic effects by targeting key mechanisms involved in muscle spasms and intestinal motility, providing a potential for managing such conditions. Full article

Globally, breast cancer is a significant cause of mortality. Recent research focused on identifying compounds regulating the transient receptor potential vanilloid 1 (TRPV1) ion channel activity for the possibility of developing cancer therapeutics. In this study, the antiproliferative properties and mechanisms of action through TRPV1 of Maclura pomifera, a dioecious tree native to the south-central USA, have been investigated. Male and female extracts of spring branch tissues and leaves (500 µg/mL) significantly reduced the viability of MCF-7 and T47D cells by 75–80%. M. pomifera extracts induced apoptosis by triggering intracellular calcium overload via TRPV1. Blocking TRPV1 with the capsazepine antagonist and pretreating cells with the BAPTA-AM chelator boosted cell viability, revealing that M. pomifera phytochemicals activate TRPV1. Both male and female M. pomifera extracts initiated apoptosis through multiple pathways, the mitochondrial, ERK-induced, and endoplasmic reticulum-stress-mediated apoptotic pathways, demonstrated by the expression of activated caspase 3, caspase 9, caspase 8, FADD, FAS, ATF4, and CHOP, the overexpression of phosphorylated PERK and ERK proteins, and the reduction of BCL-2 levels. In addition, AKT and pAKT protein expressions were reduced in female M. pomifera-treated cells, revealing that female plant extract also inhibits PI3K/Akt signaling pathways. These results suggest that phytochemicals in M. pomifera extracts could be promising for developing breast cancer therapeutics. Full article

Gabapentin (GBP) was originally developed as a potential agonist for Gamma-Amino-Butyric-Acid (GABA) receptors, aiming to inhibit the activation of pain-signaling neurons. Contrary to initial expectations, it does not bind to GABA receptors. Instead, it exhibits several distinct pharmacological activities, including: (1) binding to the alpha-2-delta protein subunit of voltage-gated calcium channels in the central nervous system, thereby blocking the excitatory influx of calcium; (2) reducing the expression and phosphorylation of CaMKII via modulation of ERK1/2 phosphorylation; (3) inhibiting glutamate release and interfering with the activation of NMDA receptors; (4) enhancing GABA synthesis; (5) increasing cell-surface expression of δGABA_A receptors, contributing to its antinociceptive, anticonvulsant, and anxiolytic-like effects. Additionally, GBP displays (6) inhibition of NF-kB activation and subsequent production of inflammatory cytokines, and (7) stimulation of the purinergic adenosine A1 receptor, which supports its anti-inflammatory and wound-healing properties. Initially approved for treating seizures and postherpetic neuralgia, GBP is now broadly used for various conditions, including psychiatric disorders, acute and chronic neuropathic pain, and sleep disturbances. Recently, as an eye drop formulation, it has also been explored as a therapeutic option for ocular surface discomfort in conditions such as dry eye, neurotrophic keratitis, corneal ulcers, and neuropathic ocular pain. This review aims to summarize the evidence supporting the molecular effects of GBP, with a special emphasis on its applications in ocular surface diseases. Full article

Ultrasound-guided regional anaesthesia with real-time visualization of anatomical structures and needle trajectory has become the standard method for accurately achieving nerve block procedures. Nevertheless, ultrasound is particularly limited in accurately detecting the needle tip in tissues with complex echogenicity. Fat-filled circumneural fascial tissue provides a barrier to local anaesthetic diffusion. Injection during gentle needle nerve contact is more likely to spread under the circumneurium (halo sign). On the other hand, excessive force may cause hematoma or activate the piezo ion channels and intraneural calcium release. Therefore, it is vital to understand the mechanics of needle–tissue interaction for optimizing the procedural outcomes and patients’ safety. We hypothesised that continuous fluid infusion would reduce the needle force applied on the nerve compared to that of bolus injection. Thus, the primary objective of this study was to compare the forces associated with the bolus injection and continuous infusion techniques on the sciatic nerves of fresh lamb legs ex vivo. A needle combining pressure and force was inserted into six legs of lambs ex vivo using a motor stage at a constant velocity and imaged with a linear transducer. Saline injections were block randomised to bolus injection or infusion in the muscle upon gently touching and indenting of the epineurium at nine sites on six sciatic nerves at three angles (30°, 45° and 60°) in each location. The bolus was delivered over 6 s and infused for over 60 s. The result showed less force was generated during the infusion technique when gently touching the epineurium than that of the bolus technique, with p = 0.004, with significant differences observed at a 60° angle (0.49 N, p = 0.001). The injection pressure was also lower when light epineurium touches were applied (9.6 kPa, p = 0.02) and at 60° (8.9 kPa). The time to peak pressure varied across the insertion angles (p < 0.001), with the shortest time at 60° (6.53 s). This study explores future applications by emphasizing the significance of understanding needle–tissue interaction mechanics. This understanding is crucial for optimizing the procedural outcomes and enhancing patients’ safety in ultrasound-guided regional anaesthesia administration. Specifically, continuous infusion demonstrated a notable reduction in needle force compared to that of the bolus injection, especially during gentle epineurium contact. Full article