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Pharmaceuticals (Basel, Switzerland) Nov 2023Cleomin, a 1,3-oxazolidine-2-thione, was recently isolated from , a species traditionally used for treating painful conditions. Reports about the pharmacological...
Cleomin, a 1,3-oxazolidine-2-thione, was recently isolated from , a species traditionally used for treating painful conditions. Reports about the pharmacological activities of cleomin are lacking. Here, the antinociceptive effects of cleomin were investigated using mice models of pain, namely the formalin, the cold plate, and the tail flick tests. Motor integrity was assessed in the rota-rod test. Antagonism assays and in silico docking analyses were performed to investigate the putative mechanisms of action. Cleomin (12.5-25 mg/kg), at doses that did not induce motor impairment, induced dose-dependent antinociception in both early and late phases of the formalin test and reduced nociceptive behaviors in both the cold plate and tail flick tests. Pretreatments with phaclofen and atropine attenuated the antinociceptive effects of cleomin, implicating the involvement of GABA and muscarinic receptors. In silico docking studies suggested satisfactory coupling between cleomin and GABA and M receptors, hence corroborating their role in cleomin's activity. Pretreatments with naloxone, yohimbine, bicuculline, and methysergide did not affect the antinociception of cleomin. In silico pharmacokinetics prediction showed a good drug ability profile of cleomin. In conclusion, cleomin promoted antinociception mediated by GABA and muscarinic receptors. These findings support further investigation of the analgesic potential of cleomin.
PubMed: 38004413
DOI: 10.3390/ph16111547 -
Bioinformation 2023Paclitaxel is a widely used cancer chemotherapeutic agent for many solid tumors; but peripheral neuropathy is a major limitation for its clinical use. Studies have...
Paclitaxel is a widely used cancer chemotherapeutic agent for many solid tumors; but peripheral neuropathy is a major limitation for its clinical use. Studies have demonstrated the usefulness of flavone derivatives in chemotherapy induced peripheral neuropathy. The present study evaluates the anti-neuropathic effect of 3', 4'-dihydroxyflavone on paclitaxel-induced peripheral neuropathy and the underlying mechanisms. Paclitaxel was administered to mice in a single dose of 10 mg/kg, i.p.The neuropathic behavioural parameters such as mechanical allodynia, cold allodynia and thermal hyperalgesia were assessed 24 h later. The test compound 3', 4'-dihydroxyflavone (50,100 or 200 mg/kg,s.c) was administered 30 min prior to the assessment of behavioral parameters. The possible mechanisms involving K channels, adenosine and GABA receptors were explored by employing suitable interacting drugs. Molecular docking studies to predict the binding interactions of 3', 4'-dihydroxyflavone at the above targets were also carried out. The test compound 3', 4'-dihydroxyflavoneexhibited a significant reduction in paw withdrawal response score in both mechanical and cold allodynia and also increased the tail flick response time in thermal hyperalgesia due to paclitaxel-induced neuropathy. The anti-neuropathic effect of 3', 4'-dihydroxyflavonewas significantly reversed by pre-treatment with glibenclamide, caffeine or bicuculline revealing the involvement of K channels, adenosine and GABA receptors respectively. Furthermore, the molecular docking studies indicated a favourable binding affinity and good H-bond interaction of 3', 4'-dihydroxyflavone at these targets. The findings of the present study suggests that, 3', 4'-dihydroxyflavone has anti-neuropathic effect against paclitaxel-induced peripheral neuropathy through mechanisms that involve K channels, adenosine (A) and GABA (α subunit) receptors.
PubMed: 37885774
DOI: 10.6026/97320630019754 -
Journal of Pharmaceutical Analysis Sep 2023Nonalcoholic fatty liver disease (NAFLD) has developed into the most common chronic liver disease and can lead to liver cancer. Our laboratory previously developed a...
Nonalcoholic fatty liver disease (NAFLD) has developed into the most common chronic liver disease and can lead to liver cancer. Our laboratory previously developed a novel prescription for NAFLD, "Eight Zhes Decoction" (EZD), which has shown good curative effects in clinical practice. However, the pharmacodynamic material basis and mechanism have not yet been revealed. A strategy integrating lipidomics, network pharmacology and pharmacokinetics was used to reveal the active components and mechanisms of EZD against NAFLD. The histopathological results showed that EZD attenuated the degrees of collagen deposition and steatosis in the livers of nonalcoholic steatofibrosis model mice. Furthermore, glycerophospholipid metabolism, arachidonic acid metabolism, glycerolipid metabolism and linoleic acid metabolism with phospholipase A2 group IVA (PLA2G4A) and cytochrome P450 as the core targets and 12,13--epoxyoctadecenoic acid, 12()-hydroxyeicosatetraenoic acid, leukotriene B4, prostaglandin E2, phosphatidylcholines (PCs) and triacylglycerols (TGs) as the main lipids were found to be involved in the treatment of NAFLD by EZD. Importantly, naringenin, artemetin, canadine, and bicuculline were identified as the active ingredients of EZD against NAFLD; in particular, naringenin reduces PC consumption by inhibiting the expression of PLA2G4A and thus promotes sufficient synthesis of very-low-density lipoprotein to transport excess TGs in the liver. This research provides valuable data and theoretical support for the application of EZD against NAFLD.
PubMed: 37842659
DOI: 10.1016/j.jpha.2023.05.012 -
Metabolism: Clinical and Experimental Jan 2024Growing evidence demonstrates the role of the striatal dopamine system in the regulation of glucose metabolism. Treatment with dopamine antagonists is associated with...
BACKGROUND
Growing evidence demonstrates the role of the striatal dopamine system in the regulation of glucose metabolism. Treatment with dopamine antagonists is associated with insulin resistance and hyperglycemia, while dopamine agonists are used in treatment of type 2 diabetes. The mechanism underlying striatal dopamine effects in glucose metabolism, however is not fully understood. Here, we provide mechanistic insights into the role of nucleus accumbens shell (sNAc) dopaminergic signaling in systemic glucose metabolism.
METHODS
Endogenous glucose production (EGP), blood glucose and mRNA expression in the lateral hypothalamic area (LHA) in male Wistar rats were measured following infusion of vanoxerine (VNX, dopamine reuptake inhibitor) in the sNAc. Thereafter, we analyzed projections from sNAc Drd1-expressing neurons to LHA using D1-Cre male Long-Evans rats, Cre-dependent viral tracers and fluorescence immunohistochemistry. Brain slice electrophysiology in adult mice was used to study spontaneous excitatory postsynaptic currents of sNAc Drd1-expressing neurons following VNX application. Finally, we assessed whether GABAergic LHA activity and hepatic vagal innervation were required for the effect of sNAc-VNX on glucose metabolism by combining infusion of sNAc-VNX with LHA-bicuculline, performing vagal recordings and combining infusion of sNAc-VNX with hepatic vagal denervation.
RESULTS
VNX infusion in the sNAc strongly decreased endogenous glucose production, prevented glucose increases over time, reduced Slc17A6 and Hcrt mRNA in LHA, and increased vagal activity. Furthermore, sNAc Drd1-expressing neurons increased spontaneous firing following VNX application, and viral tracing of sNAc Drd1-expressing neurons revealed direct projections to LHA with on average 67 % of orexin cells directly targeted by sNAc Drd1-expressing neurons. Importantly, the sNAc-VNX-induced effect on glucose metabolism was dependent on GABAergic signaling in the LHA and on intact hepatic vagal innervation.
CONCLUSIONS
We show that sNAc dopaminergic signaling modulates hepatic glucose metabolism through GABAergic inputs to glutamatergic LHA cells and hepatic vagal innervation. This demonstrates that striatal control of glucose metabolism involves a dopaminergic sNAc-LHA-liver axis and provides a potential explanation for the effects of dopamine agonists and antagonists on glucose metabolism.
Topics: Rats; Male; Mice; Animals; Hypothalamic Area, Lateral; Nucleus Accumbens; Dopamine; Rodentia; Dopamine Agonists; Diabetes Mellitus, Type 2; Rats, Wistar; Rats, Long-Evans; Glucose; Liver; RNA, Messenger
PubMed: 37804881
DOI: 10.1016/j.metabol.2023.155696 -
The Korean Journal of Pain Oct 2023: Hypertonic saline is used for treating chronic pain; however, clinical studies that aid in optimizing therapeutic protocols are lacking. We aimed to determine the...
BACKGROUND
: Hypertonic saline is used for treating chronic pain; however, clinical studies that aid in optimizing therapeutic protocols are lacking. We aimed to determine the concentration of intrathecally injected hypertonic saline at which the effect reaches its peak as well as the underlying γ-aminobutyric acid (GABA) receptor-related antinociceptive mechanism.
METHODS
: Spinal nerve ligation (SNL; left L5 and L6) was performed to induce neuropathic pain in rats weighing 250-300 g. Experiment 1: one week after implanting the intrathecal catheter, 60 rats were assigned randomly to intrathecal injection with 0.45%, 0.9%, 2.5%, 5%, 10%, and 20% NaCl, followed by behavioral testing at baseline and after 30 minutes, 2 hours, 1 day, and 1 week to determine the minimal concentration which produced maximal analgesia. Experiment 2: after determining the optimal intrathecal hypertonic saline concentration, 60 rats were randomly divided into four groups: Sham, hypertonic saline without pretreatment, and hypertonic saline after pretreatment with one of two GABA receptor antagonists (GABA [bicuculline], or GABA [phaclofen]). Behavioral tests were performed at weeks 1 and 3 following each treatment.
RESULTS
: Hypertonic saline at concentrations greater than 5% alleviated SNL-induced mechanical allodynia and had a significant therapeutic effect, while showing a partial time- and dose-dependent antinociceptive effect on thermal and cold hyperalgesia. However, pretreatment with GABA receptor antagonists inhibited the antinociceptive effect of 5% NaCl.
CONCLUSIONS
: This study indicates that the optimal concentration of hypertonic saline for controlling mechanical allodynia in neuropathic pain is 5%, and that its analgesic effect is related to GABA and GABA receptors.
PubMed: 37722756
DOI: 10.3344/kjp.23162 -
The Journal of Experimental Biology Oct 2023Fossorial Damaraland mole-rats (Fukomys damarensis) mount a robust hypoxic metabolic response (HMR) but a blunted hypoxic ventilatory response (HVR) to acute hypoxia....
Fossorial Damaraland mole-rats (Fukomys damarensis) mount a robust hypoxic metabolic response (HMR) but a blunted hypoxic ventilatory response (HVR) to acute hypoxia. Although these reflex physiological responses have been described previously, the underlying signalling pathways are entirely unknown. Of particular interest are contributions from γ-aminobutyric acid (GABA), which is the primary inhibitory neurotransmitter in the nervous system of most adult mammals, and adenosine, the accumulation of which increases during hypoxia as a breakdown product of ATP. Therefore, we hypothesized that GABAergic and/or adenosinergic signalling contributes to the blunted HVR and robust HMR in Damaraland mole-rats. To test this hypothesis, we injected adult animals with saline alone (controls), or 100 mg kg-1 aminophylline or 1 mg kg-1 bicuculline, to block adenosine or GABAA receptors, respectively. We then used respirometry, plethysmography and thermal RFID probes to non-invasively measure metabolic, ventilator and thermoregulatory responses, respectively, to acute hypoxia (1 h in 5 or 7% O2) in awake and freely behaving animals. We found that bicuculline had relatively minor effects on metabolism and thermoregulation but sensitized ventilation such that the HVR became manifest at 7% instead of 5% O2 and was greater in magnitude. Aminophylline increased metabolic rate, ventilation and body temperature in normoxia, and augmented the HMR and HVR. Taken together, these findings indicate that adenosinergic and GABAergic signalling play important roles in mediating the robust HMR and blunted HVR in Damaraland mole-rats.
Topics: Animals; Bicuculline; Aminophylline; Adenosine; Mole Rats; Hypoxia; gamma-Aminobutyric Acid
PubMed: 37694288
DOI: 10.1242/jeb.246186 -
Frontiers in Cellular Neuroscience 2023The paraventricular nucleus of the hypothalamus (PVN) contains premotor neurons involved in the control of sympathetic vasomotor activity. It is known that the...
Frequency-coded patterns of sympathetic vasomotor activity are differentially evoked by the paraventricular nucleus of the hypothalamus in the Goldblatt hypertension model.
INTRODUCTION
The paraventricular nucleus of the hypothalamus (PVN) contains premotor neurons involved in the control of sympathetic vasomotor activity. It is known that the stimulation of specific areas of the PVN can lead to distinct response patterns at different target territories. The underlying mechanisms, however, are still unclear. Recent evidence from sympathetic nerve recording suggests that relevant information is coded in the power distribution of the signal along the frequency range. In the present study, we addressed the hypothesis that the PVN is capable of organizing specific spectral patterns of sympathetic vasomotor activation to distinct territories in both normal and hypertensive animals.
METHODS
To test it, we investigated the territorially differential changes in the frequency parameters of the renal and splanchnic sympathetic nerve activity (rSNA and sSNA, respectively), before and after disinhibition of the PVN by bicuculline microinjection. Subjects were control and Goldblatt rats, a sympathetic overactivity-characterized model of neurogenic hypertension (2K1C). Additionally, considering the importance of angiotensin II type 1 receptors (AT1) in the sympathetic responses triggered by bicuculline in the PVN, we also investigated the impact of angiotensin AT1 receptors blockade in the spectral features of the rSNA and sSNA activity.
RESULTS
The results revealed that each nerve activity (renal and splanchnic) presents its own electrophysiological pattern of frequency-coded rhythm in each group (control, 2K1C, and 2K1C treated with AT1 antagonist losartan) in basal condition and after bicuculline microinjection, but with no significant differences regarding total power comparison among groups. Additionally, the losartan 2K1C treated group showed no decrease in the hypertensive response triggered by bicuculline when compared to the non-treated 2K1C group. However, their spectral patterns of sympathetic nerve activity were different from the other two groups (control and 2K1C), suggesting that the blockade of AT1 receptors does not totally recover the basal levels of neither the autonomic responses nor the electrophysiological patterns in Goldblatt rats, but act on their spectral frequency distribution.
DISCUSSION
The results suggest that the differential responses evoked by the PVN were preferentially coded in frequency, but not in the global power of the vasomotor sympathetic responses, indicating that the PVN is able to independently control the frequency and the power of sympathetic discharges to different territories.
PubMed: 37674868
DOI: 10.3389/fncel.2023.1176634 -
Neuron Nov 2023The neurotransmitter γ-aminobutyric acid (GABA) drives critical inhibitory processes in and beyond the nervous system, partly via ionotropic type-A receptors (GABARs)....
The neurotransmitter γ-aminobutyric acid (GABA) drives critical inhibitory processes in and beyond the nervous system, partly via ionotropic type-A receptors (GABARs). Pharmacological properties of ρ-type GABARs are particularly distinctive, yet the structural basis for their specialization remains unclear. Here, we present cryo-EM structures of a lipid-embedded human ρ1 GABAR, including a partial intracellular domain, under apo, inhibited, and desensitized conditions. An apparent resting state, determined first in the absence of modulators, was recapitulated with the specific inhibitor (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid and blocker picrotoxin and provided a rationale for bicuculline insensitivity. Comparative structures, mutant recordings, and molecular simulations with and without GABA further explained the sensitized but slower activation of ρ1 relative to canonical subtypes. Combining GABA with picrotoxin also captured an apparent uncoupled intermediate state. This work reveals structural mechanisms of gating and modulation with applications to ρ-specific pharmaceutical design and to our biophysical understanding of ligand-gated ion channels.
Topics: Humans; Receptors, GABA-A; Picrotoxin; Ligands; gamma-Aminobutyric Acid; Bicuculline; Binding Sites
PubMed: 37659407
DOI: 10.1016/j.neuron.2023.08.006 -
Foods (Basel, Switzerland) Jul 2023Although Mill (jujube) is used in folk medicine for hypnotic sedative, anxiolytic, and many other purposes, to date, only a few studies have revealed its...
Although Mill (jujube) is used in folk medicine for hypnotic sedative, anxiolytic, and many other purposes, to date, only a few studies have revealed its sleep-promoting effects and related mechanisms. Currently, drugs used for the treatment of sleep disorders have various side effects, so it is essential to develop safe natural materials. Therefore, we evaluated the sleep-enhancing activity and mechanism of action of an aqueous extract of jujube seeds (ZW) fermented with L-32 in rodent models. The starch contained in ZW was removed by enzymatic degradation and fermented with to obtain a fermented product (ZW-FM) with a high γ-aminobutyric acid (GABA) content. To evaluate the sleep-promoting effect of ZW-FM, pentobarbital-induced sleep tests were performed on ICR mice, and electroencephalography analysis was undertaken in Sprague Dawley rats. Additionally, the awakening relief effects of ZW-FM were confirmed in a caffeine-induced insomnia model. Finally, the mechanism of sleep enhancement by ZW-FM was analyzed using GABA receptor type A (GABA) antagonists. The ZW-FM-treated groups (100 and 150 mg/kg) showed increased sleep time, especially the δ-wave time during non-rapid eye movement (NREM) sleep. In addition, the 150 mg/kg ZW-FM treatment group showed decreased sleep latency and increased sleep time in the insomnia model. In particular, NREM sleep time was increased and REM sleep time, which was increased by caffeine treatment, was decreased by ZW-FM treatment. ZW-FM-induced sleep increase was inhibited by the GABA receptor antagonists picrotoxin, bicuculline, and flumazenil, confirming that the increase was the result of a GABAergic mechanism. These results strongly suggest that the increased GABA in water extract from jujube seeds fermented by acts as a sleep-promoting compound and that the sleep-promoting activity is related to GABA receptor binding.
PubMed: 37569133
DOI: 10.3390/foods12152864 -
International Journal of Molecular... Jul 2023Abnormal depolarization of neuronal membranes called paroxysmal depolarization shift (PDS) represents a cellular correlate of interictal spikes. The mechanisms...
Abnormal depolarization of neuronal membranes called paroxysmal depolarization shift (PDS) represents a cellular correlate of interictal spikes. The mechanisms underlying the generation of PDSs or PDS clusters remain obscure. This study aimed to investigate the role of ionotropic glutamate receptors (iGluRs) in the generation of PDS and dependence of the PDS pattern on neuronal membrane potential. We have shown that significant depolarization or hyperpolarization (by more than ±50 mV) of a single neuron does not change the number of individual PDSs in the cluster, indicating the involvement of an external stimulus in PDS induction. Based on this data, we have suggested reliable protocols for stimulating single PDS or PDS clusters. Furthermore, we have found that AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors are necessary for PDS generation since AMPAR antagonist NBQX completely suppresses bicuculline-induced paroxysmal activity. In turn, antagonists of NMDA (N-methyl-D-aspartate) and kainate receptors (D-AP5 and UBP310, respectively) caused a decrease in the amplitude of the first action potential in PDSs and in the amplitude of the oscillations of intracellular Ca concentration occurring alongside the PDS cluster generation. The effects of the NMDAR (NMDA receptor) and KAR (kainate receptor) antagonists indicate that these receptors are involved only in the modulation of paroxysmal activity. We have also shown that agonists of some G-coupled receptors, such as A adenosine (ARs) or cannabinoid receptors (CBRs) (N-cyclohexyladenosine and WIN 55,212-2, respectively), completely suppressed PDS generation, while the AR agonist even prevented it. We hypothesized that the dynamics of extracellular glutamate concentration govern paroxysmal activity. Fine-tuning of neuronal activity via action on G-coupled receptors or iGluRs paves the way for the development of new approaches for epilepsy pharmacotherapy.
Topics: Rats; Animals; Bicuculline; Hippocampus; Receptors, N-Methyl-D-Aspartate; Neurons; Action Potentials; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
PubMed: 37446169
DOI: 10.3390/ijms241310991