Eperisone Hydrochloride, a Muscle Relaxant, Is a Potent P2X7 Receptor Antagonist

Eperisone Hydrochloride was launched in Japan in 1983 and has been used to improve muscle tone and treat spastic paralysis (Originator: Eisai Co., Ltd.). However, its biochemical mechanism of action is unknown. SB Drug Discovery was used to evaluate purinergic P2X (P2X) receptor antagonism using fluorescence. In this study, we discovered that its target protein is the P2X7 receptor. Also, P2X receptor subtype selectivity was high. This finding demonstrates the (Eperisone-P2X7-pain linkage), the validity of P2X7 as a drug target, and the possibility of drug repositioning of Eperisone Hydrochloride.

Moxifloxacin and gemifloxacin mediates its antispasmodic profile via ATP-sensitive potassium channels: An in-vitro bioassay study

Moxifloxacin and gemifloxacin were tested on isolated rabbits' jejunal preparations as little is known about its effects on gastrointestinal tissues. Moxifloxacin and gemifloxacin were tested in concentrations 0.01-10μg/mL for possible effect(s) on isolated rabbits' jejunal preparations. The drugs were applied on spontaneous, on low K⁺ (20mM)-induced contractions and on high K⁺ (80mM)-induced contractions. Response was plotted as % of its respective controls. EC50 for Moxifloxacin and Gemifloxacin on spontaneous (without Glibenclamide) contractions are 2.83±0.5μg/mL and 1.11±0.2μg/mL, respectively. Moxifloxacin and Gemifloxacin relaxed the low K+ (20mM) -induced contractions, which were inhibited in presence of Glibenclamide (3μM). Our result indicates that the relaxant activity of Moxifloxacin and Gemifloxacin is mediated possibly through activation of ATP-sensitive potassium channels (KATP). The relaxant effect of Moxifloxacin and Gemifloxacin is predominantly mediated by activation of ATP-Sensitive potassium channels (K_ATP), which could be cause of one of relaxing mechanisms.

Calcium ions trigger the exposure of phosphatidylserine on the surface of necrotic cells

Intracellular Ca²⁺ level is under strict regulation through calcium channels and storage pools including the endoplasmic reticulum (ER). Mutations in certain ion channel subunits, which cause mis-regulated Ca²⁺ influx, induce the excitotoxic necrosis of neurons. In the nematode Caenorhabditis elegans, dominant mutations in the DEG/ENaC sodium channel subunit MEC-4 induce six mechanosensory (touch) neurons to undergo excitotoxic necrosis. These necrotic neurons are subsequently engulfed and digested by neighboring hypodermal cells. We previously reported that necrotic touch neurons actively expose phosphatidylserine (PS), an “eat-me” signal, to attract engulfing cells. However, the upstream signal that triggers PS externalization remained elusive. Here we report that a robust and transient increase of cytoplasmic Ca²⁺ level occurs prior to the exposure of PS on necrotic touch neurons. Inhibiting the release of Ca²⁺ from the ER, either pharmacologically or genetically, specifically impairs PS exposure on necrotic but not apoptotic cells. On the contrary, inhibiting the reuptake of cytoplasmic Ca²⁺ into the ER induces ectopic necrosis and PS exposure. Remarkably, PS exposure occurs independently of other necrosis events. Furthermore, unlike in mutants of DEG/ENaC channels, in dominant mutants of deg-3 and trp-4, which encode Ca²⁺ channels, PS exposure on necrotic neurons does not rely on the ER Ca²⁺ pool. Our findings indicate that high levels of cytoplasmic Ca²⁺ are necessary and sufficient for PS exposure. They further reveal two Ca²⁺-dependent, necrosis-specific pathways that promote PS exposure, a “two-step” pathway initiated by a modest influx of Ca²⁺ and further boosted by the release of Ca²⁺ from the ER, and another, ER-independent, pathway. Moreover, we found that ANOH-1, the worm homolog of mammalian phospholipid scramblase TMEM16F, is necessary for efficient PS exposure in thapsgargin-treated worms and trp-4 mutants, like in mec-4 mutants. We propose that both the ER-mediated and ER-independent Ca²⁺ pathways promote PS externalization through activating ANOH-1.

Necrosis is a type of cell death that exhibits distinct morphological features such as cell and organelle swelling. Necrotic cells expose phosphatidylserine (PS)–a type of phospholipid—on their outer surfaces. Receptor molecules on phagocytes detect PS on necrotic cells and subsequently initiate the engulfment process. As necrosis is associated with stroke, cancer, neurodegenerative diseases, and heart diseases, studying necrotic cell clearance has important medical relevance. In the model organism the nematode C. elegans, we previously identified membrane proteins that promote the exposure of PS on necrotic cell surfaces by studying neurons that are induced to undergo necrosis by dominant mutations in ion channels. Here, in C. elegans, we have discovered that the necrotic insults trigger an increase of the cytoplasmic calcium ion (Ca²⁺), which in turn promotes PS externalization on necrotic cell surfaces. Furthermore, we have identified two different mechanisms that increase cytoplasmic Ca²⁺ levels, one dependent on the Ca²⁺ contribution from the endoplasmic reticulum (ER), the other independent of the ER. The Ca²⁺ signal targets ANOH-1, a worm homolog of mammalian proteins capable of externalizing PS, for promoting PS exposure on necrotic cells. Our findings reveal novel upstream regulatory mechanisms that promote necrotic cell clearance in animals.

Cholinergic Chemotransmission and Anesthetic Drug Effects at the Carotid Bodies

General anesthesia is obtained by administration of potent hypnotics, analgesics and muscle relaxants. Apart from their intended effects (loss of consciousness, pain relief and muscle relaxation), these agents profoundly affect the control of breathing, in part by an effect within the peripheral chemoreflex loop that originates at the carotid bodies. This review assesses the role of cholinergic chemotransmission in the peripheral chemoreflex loop and the mechanisms through which muscle relaxants and hypnotics interfere with peripheral chemosensitivity. Additionally, consequences for clinical practice are discussed.

Analysis of Drug Effects on iPSC Cardiomyocytes with Machine Learning

Patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) offer an attractive experimental platform to investigate cardiac diseases and therapeutic outcome. In this study, iPSC-CMs were utilized to study their calcium transient signals and drug effects by means of machine learning, a central part of artificial intelligence. Drug effects were assessed in six iPSC-lines carrying different mutations causing catecholaminergic polymorphic ventricular tachycardia (CPVT), a highly malignant inherited arrhythmogenic disorder. The antiarrhythmic effect of dantrolene, an inhibitor of sarcoplasmic calcium release, was studied in iPSC-CMs after adrenaline, an adrenergic agonist, stimulation by machine learning analysis of calcium transient signals. First, beats of transient signals were identified with our peak recognition algorithm previously developed. Then 12 peak variables were computed for every identified peak of a signal and by means of this data signals were classified into different classes corresponding to those affected by adrenaline or, thereafter, affected by a drug, dantrolene. The best classification accuracy was approximately 79% indicating that machine learning methods can be utilized in analysis of iPSC-CM drug effects. In the future, data analysis of iPSC-CM drug effects together with machine learning methods can create a very valuable and efficient platform to individualize medication in addition to drug screening and cardiotoxicity studies.

Dantrolene Ameliorates Impaired Neurogenesis and Synaptogenesis in Induced Pluripotent Stem Cell Lines Derived from Patients with Alzheimer's Disease

BACKGROUND

Overactivation of ryanodine receptors and the resulting impaired calcium homeostasis contribute to Alzheimer's disease-related pathophysiology. This study hypothesized that exposing neuronal progenitors derived from induced pluripotent stems cells of patients with Alzheimer's disease to dantrolene will increase survival, proliferation, neurogenesis, and synaptogenesis.

METHODS

Induced pluripotent stem cells obtained from skin fibroblast of healthy subjects and patients with familial and sporadic Alzheimer's disease were used. Biochemical and immunohistochemical methods were applied to determine the effects of dantrolene on the viability, proliferation, differentiation, and calcium dynamics of these cells.

RESULTS

Dantrolene promoted cell viability and proliferation in these two cell lines. Compared with the control, differentiation into basal forebrain cholinergic neurons significantly decreased by 10.7% (32.9 ± 3.6% vs. 22.2 ± 2.6%, N = 5, P = 0.004) and 9.2% (32.9 ± 3.6% vs. 23.7 ± 3.1%, N = 5, P = 0.017) in cell lines from sporadic and familial Alzheimer's patients, respectively, which were abolished by dantrolene. Synapse density was significantly decreased in cortical neurons generated from stem cells of sporadic Alzheimer's disease by 58.2% (237.0 ± 28.4 vs. 99.0 ± 16.6 arbitrary units, N = 4, P = 0.001) or familial Alzheimer's disease by 52.3% (237.0 ± 28.4 vs.113.0 ± 34.9 vs. arbitrary units, N = 5, P = 0.001), which was inhibited by dantrolene in the familial cell line. Compared with the control, adenosine triphosphate (30 µM) significantly increased higher peak elevation of cytosolic calcium concentrations in the cell line from sporadic Alzheimer's patients (84.1 ± 27.0% vs. 140.4 ± 40.2%, N = 5, P = 0.049), which was abolished by the pretreatment of dantrolene. Dantrolene inhibited the decrease of lysosomal vacuolar-type H-ATPase and the impairment of autophagy activity in these two cell lines from Alzheimer's disease patients.

CONCLUSIONS

Dantrolene ameliorated the impairment of neurogenesis and synaptogenesis, in association with restoring intracellular Ca homeostasis and physiologic autophagy, cell survival, and proliferation in induced pluripotent stem cells and their derived neurons from sporadic and familial Alzheimer's disease patients.

Methanol Extract of Dicranopteris linearis Leaves Attenuate Pain via the Modulation of Opioid/NO-Mediated Pathway

Dicranopteris linearis leaf has been reported to exert antinociceptive activity. The present study elucidates the possible mechanisms of antinociception modulated by the methanol extract of D. linearis leaves (MEDL) using various mouse models. The extract (25, 150, and 300 mg/kg) was administered orally to mice for 30 min priot to subjection to the acetic acid-induced writhing-, hot plate- or formalin-test to establish the antinociceptive profile of MEDL. The most effective dose was then used in the elucidation of possible mechanisms of action stage. The extract was also subjected to the phytochemical analyses. The results confirmed that MEDL exerted significant (p < 0.05) antinociceptive activity in those pain models as well as the capsaicin-, glutamate-, bradykinin- and phorbol 12-myristate 13-acetate (PMA)-induced paw licking model. Pretreatment with naloxone (a non-selective opioid antagonist) significantly (p < 0.05) reversed MEDL effect on thermal nociception. Only l-arginine (a nitric oxide (NO) donor) but not N(ω)-nitro-l-arginine methyl ester (l-NAME; a NO inhibitor) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; a specific soluble guanylyl cyclase inhibitor) significantly (p < 0.05) modified MEDL effect on the writhing test. Several polyphenolics and volatile antinociceptive compounds were detected in MEDL. In conclusion, MEDL exerted the opioid/NO-mediated antinociceptive activity, thus, justify D. linearis as a potential source for new analgesic agents development.

Effect of methanol extract of Trigonella foenum-graecum L. seeds on anxiety, sedation and motor coordination

Currently available anxiolytics cause numerous adverse effects and show craving and tolerance during long term treatment. Currently traditional medicines have been re-evaluated widely through work on various plant species. Numerous plants in traditional system show pharmacological activity with unlimited prospective for therapeutic use. Hence we planned to evaluate the effect of methanol extract of T. foenum-graecum L. seeds on anxiety, sedation and motor coordination in mice at different doses following 15 days of oral feeding. Effect on anxiety was assessed by Hole board test and Light and Dark transition models.Phenobarbitone induced sleeping time and Rota rod test were performed to assess effect on sedation and motor coordination. In Hole board test, T. foenum-graecum L. seeds decreased the number of head dips in mice at all the three doses. In Light and Dark transition model, T. foenum-graecum L. seeds increased the period spent in the light box and the number of moves among the two compartments at 100 and 200 mg/kg as compared to control animals. In phenobarbitone induced sleeping time, T. foenum-graecum L. seeds did not reveal any sedative effect. In Rota rod test, extract exhibited significant skeletal muscle relaxant effect at 200 mg/kg (at 90 min) as compared to the control animals. Results of our study shows significant antianxiety effects of T. foenum-graecum L. seeds and may also recommend improved adverse effect profile as compared to diazepam.

Synthesis, Computational and Pharmacological Evaluation of N-(2-benzoyl- 4-chlorophenyl)-2-(4-(Substituted Phenyl) Piperazin-1-yl) Acetamides as CNS Agents

BACKGROUND

A series of new N-(2-benzoyl-4-chlorophenyl)-2-(4-(substituted phenyl) piperazin-1-yl) acetamides (3a-j) have been synthesized by the chloroacetylation of 2-amino-5- chlorbenzophenone which was further reacted with substituted phenylpiperazine.

MATERIAL

The chemical structures of the compounds were confirmed on the basis of their TLC, IR, 1HNMR, 13CNMR and by elemental analysis. The physicochemical similarity of the target compounds with respect to standard drug diazepam was assessed by calculating from a set of physicochemical properties using software programs.

CONCLUSION

Molecular docking studies revealed that the target compounds correctly dock into the binding pocket of the GABAA receptor, while their bioavailability/drug-likeness was predicted to be acceptable but requires future optimization. The anxiolytic and skeletal muscle relaxant activity of the target compounds (3a-j) were evaluated in albino mice. Among them, compound 3h showed potent anxiolytic and skeletal muscle relaxant activity.

Nociception-specific blink reflex: pharmacology in healthy volunteers

BACKGROUND

The physiology and pharmacology of activation or perception of activation of pain-coding trigeminovascular afferents in humans is fundamental to understanding the biology of headache and developing new treatments.

METHODS

The blink reflex was elicited using a concentric electrode and recorded in four separate sessions, at baseline and two minutes after administration of ramped doses of diazepam (final dose 0.07 mg/kg), fentanyl (final dose 1.11 μg/kg), ketamine (final dose 0.084 mg/kg) and 0.9 % saline solution. The AUC (area under the curve, μV*ms) and the latency (ms) of the ipsi- and contralateral R2 component of the blink reflex were calculated by PC-based offline analysis. Immediately after each block of blink reflex recordings certain psychometric parameters were assessed.

RESULTS

There was an effect due to DRUG on the ipsilateral (F 3,60 = 7.3, P < 0.001) AUC as well as on the contralateral (F 3,60 = 6.02, P < 0.001) AUC across the study. A significant decrement in comparison to placebo was observed only for diazepam, affecting the ipsilateral AUC. The scores of alertness, calmness, contentedness, reaction time and precision were not affected by the DRUG across the sessions.

CONCLUSION

Previous studies suggest central, rather than peripheral changes in nociceptive trigeminal transmission in migraine. This study demonstrates a robust effect of benzodiazepine receptor modulation of the nociception specific blink reflex (nBR) without any μ-opiate or glutamate NMDA receptor component. The nociception specific blink reflex offers a reproducible, quantifiable method of assessment of trigeminal nociceptive system in humans that can be used to dissect pharmacology relevant to primary headache disorders.

Mouth rinsing and ingestion of a bitter-tasting solution increases corticomotor excitability in male competitive cyclists

PURPOSE

Recently, we have shown that the combination of mouth rinsing and ingesting a bitter-tasting quinine solution immediately prior to the performance of a maximal 30-s cycling sprint significantly improves mean and peak power output. This ergogenic effect was proposed to be related to the activation of the corticomotor pathway by afferent taste signals originating from bitter taste receptors in the oral cavity. The aim of the present study was to use single-pulse transcranial magnetic stimulation to investigate whether mouth rinsing and ingestion of a bitter quinine solution increases corticomotor excitability.

METHODS

A series of 10 motor-evoked potentials (MEPs) were recorded from the relaxed first dorsal interosseus muscle in 16 male competitive cyclists immediately before and after they rinsed their mouth for 10 s and then ingested either a 2 mM bitter quinine solution or plain water.

RESULTS

Mean MEP amplitude was significantly increased in response to quinine administration by 16% (p < 0.05), with no evidence of a time-dependent effect over the 10 pulses. Mean MEP amplitude also increased by 10% in response to water administration (p < 0.05), though this increase was significantly smaller than the response to quinine (p < 0.05).

CONCLUSIONS

We conclude that the activation of bitter taste receptors in the oral cavity and upper gastrointestinal tract has the capacity to increase corticomotor excitability in male competitive cyclists.

Sevoflurane inhibits nuclear factor-κB activation in lipopolysaccharide-induced acute inflammatory lung injury via toll-like receptor 4 signaling

Background

Infection is a common cause of acute lung injury (ALI). This study was aimed to explore whether Toll-like receptors 4 (TLR₄) of airway smooth muscle cells (ASMCs) play a role in lipopolysaccharide (LPS)-induced airway hyperresponsiveness and potential mechanisms.

Methods

In vivo: A sensitizing dose of LPS (50 µg) was administered i.p. to female mice before anesthesia with either 3% sevoflurane or phenobarbital i.p. After stabilization, the mice were challenged with 5 µg of intratracheal LPS to mimic inflammatory attack. The effects of sevoflurane were assessed by measurement of airway responsiveness to methacholine, histological examination, and IL-1, IL-6, TNF-α levels in bronchoalveolar lavage fluid (BALF). Protein and gene expression of TLR₄ and NF-κB were also assessed. In vitro: After pre-sensitization of ASMCs and ASM segments for 24h, levels of TLR₄ and NF-κB proteins in cultured ASMCs were measured after continuous LPS exposure for 1, 3, 5, 12 and 24h in presence or absence of sevoflurane. Constrictor and relaxant responsiveness of ASM was measured 24 h afterwards.

Results

The mRNA and protein levels of NF-κB and TLR₄ in ASM were increased and maintained at high level after LPS challenge throughout 24h observation period, both in vivo and in vitro. Sevoflurane reduced LPS-induced airway hyperresponsiveness, lung inflammatory cell infiltration and proinflammatory cytokines release in BALF as well as maximal isometric contractile force of ASM segments to acetylcholine, but it increased maximal relaxation response to isoproterenol. Treatment with specific NF-κB inhibitor produced similar protections as sevoflurane, including decreased expressions of TLR₄ and NF-κB in cultured ASMCs and improved pharmacodynamic responsiveness of ASM to ACh and isoproterenol.

Conclusions

This study demonstrates the crucial role of TLR₄ activation in ASMCs during ALI in response to LPS. Sevoflurane exerts direct relaxant and anti-inflammatory effects in vivo and in vitro via inhibition of TLR₄/NF-κB pathway.

Effects of methylprednisolone, dantrolene, and their combination on experimental spinal cord injury

This study aimed to evaluate the effect of methylprednisolone sodium succinate, dantrolene sodium, and their combination on experimental spinal cord injury. We used 25 rats (Rattus norvegicus) that were divided into five groups. The negative control group (NC) consisted of animals without spinal cord trauma. In the groups with spinal cord trauma, the positive control group (PC) was given no treatment, the MS group was treated with methylprednisolone, the MS/DS group was treated with methylprednisolone and dantrolene, and the DS group was treated with dantrolene alone. The animals' motor function was evaluated daily, as measured with the open field test. Eight days after surgery, the animals were euthanized for spinal cord collection. Descriptive morphological evaluation, anti-NeuN immunohistochemistry, TUNEL, and anti-Bax immunofluorescence were performed. There was no significant difference between the PC, MS, MS/DS and DS groups with respect to BBB scores, neuronal and glial staining, or Bax expression (P < 0.05). Therefore, we conclude that methylprednisolone sodium succinate, dantrolene sodium, or the combination of these drugs did not reduce neuronal and glial loss, intrinsic pathway apoptosis, or promote functional recovery.

[Aqueous and salt solutions of quinine of low concentrations: self-organization, physicochemical properties and actions on the electrical characteristics of neurons]

Self-organization, the physicochemical properties of aqueous and salt solutions of quinine and the effects of salt quinine solutions in a wide range of concentrations (1 x 10(-22) - 1 x 10(-3) M) on the electrical characteristics of the edible snail's identified neurons were studied. Similar non-monotonic concentration dependencies of physicochemical properties of aqueous and salt quinine solutions at low concentrations are obtained. This allows of predicting the occurrence of biological effects at low concentrations of quinine solutions. Intrinsic (within 5% of the interval) changes in membrane potential, the amplitude and duration of the neuron action potential under the influence of quinine salt solutions at concentrations of quinine of 1 x 10(-20), 1 x 10(-18), 1 x 10(-10) M are found. For these concentrations the extreme values of specific conductivity and pH are shown.

[Influence of mydocalm on the degree of intra-abdominal hypertension and local blood circulation in the intestinal wall in experiment]

The effect of mydocalm (tolperison, 5 mg/kg single dose) on the dynamics of intra-abdominal hypertension (IAH), blood circulation regulation, and oxygen balance in the tissues of intestinal wall were studied in acute experiments on rabbits. Using a special stand of original design, the initial IAH level was modeled at 200 mm H2O with the subsequent stopping of further receipt of liquid during 3 hours in an elastic container in the abdominal cavity. During 3-h observation without drug administration, no changes in IAH due to the tone of muscles of the frontal abdominal wall takes place, but there is progressive deceleration of local blood flow (-35.33 + 0.99%, p < 0.01), suppressed dilation (-20.02 + 0.54%, p < 0.01) and constriction (-60.45 + 1.17%, p < 0.01) reactivity of vessels, and decreased oxygen tension (-47.18 + 0.75%, p < 0.01) in the intestinal wall at the end of experiment. The introduction of mydocalm reduces the tone of muscles of the frontal abdominal wall, which leads to a decrease in IAH (maximum effect after 1.5 hours, -20.81 + 0.84%, p < 0.01) and prevents decrease in the local blood flow (-26.77 + 0.41%, p < 0.01), suppression of dilation (-16.51 + 0.34%, p < 0.01) and constriction (-37.85 + 0.61%, p < 0.01) reactivity of vessels, and reduction in oxygen tension (-36.60 + 1.18%, p < 0.01) at the end of experiment. The administration of mydocalm can extend the limits of application of a conservative therapy for patients with IAH and to improve the results.

Effects of aescin on cytochrome P450 enzymes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Aescin, the main active component found in extracts of horse chestnut (Aesculus hippocastanum) seed a traditional medicinal herb, is a mixture of triterpene saponins. It has been shown to be effective in inflammatory, chronic venous and edematous treatment conditions in vitro and in vivo, and is broadly used to treat chronic venous insufficiency. The purpose of this study was to find out whether aescin influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo; the influence on the levels of CYP mRNA was also studied.

MATERIALS AND METHODS

A cocktail solution at a dose of 5mL/kg, which contained phenacetin (20mg/kg), tolbutamide (5mg/kg), chlorzoxazone (20mg/kg) and midazolam (10mg/kg), was given as oral administration to rats treated with a single dose or multiple doses of intravenous aescin via the caudal vein. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0. In addition, real-time RT-PCR was performed to determine the effects of aescin on the mRNA expression of CYP1A2, CYP2C9, CYP2E1 and CYP3A4 in rat liver.

RESULTS

Treatment with a single dose or multiple doses of aescin had inductive effects on rat CYP1A2, while CYP2C9 and CYP3A4 enzyme activities were inhibited. Moreover, aescin has no inductive or inhibitory effect on the activity of CYP2E1. The mRNA expression results were in accordance with the pharmacokinetic results.

CONCLUSIONS

Aescin can either inhibit or induce activities of CYP1A2, CYP2C9 and CYP3A4. Therefore, caution is needed when aescin is co-administration with some CYP1A2, CYP2C9 or CYP3A4 substrates in clinic, which may result in treatment failure and herb-drug interactions.

Possible involvement of AMPK in acute exercise-induced expression of monocarboxylate transporters MCT1 and MCT4 mRNA in fast-twitch skeletal muscle

OBJECTIVE

The regulatory mechanisms responsible for acute exercise-induced expression of monocarboxylate transporters MCT1 and MCT4 mRNA in skeletal muscle remain unclear. 5'-adenosine-activated protein kinase (AMPK) is a key signaling molecule that regulates gene expression at the mRNA level. We examined whether AMPK activation is involved in acute exercise-induced expression of MCT1 and MCT4 mRNA in fast-twitch muscle.

MATERIALS/METHODS

Male Sprague-Dawley rats were subjected to an acute bout of either 5min high-intensity intermittent swimming (HIS) or 6-h low-intensity prolonged swimming (LIS). The effects of acute exercise on the phosphorylation of AMPK (p-AMPK), calcium/calmodulin pendent kinase II (p-CaMKII), p38 mitogen-activated protein kinase (p-p38MAPK), and MCTs mRNA were analyzed in vivo. To observe the direct effects of AMPK activation on MCTs mRNA, the effects of 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR), caffeine, and dantrolene were analyzed in vitro using an isolated muscle incubation model.

RESULTS

The p-AMPK increased in response to both HIS and LIS, although the p-CaMKII and p-p38MAPK were increased only following HIS. Irrespective of exercise intensity, MCT1 and MCT4 mRNA was also transiently upregulated by both HIS and LIS. Direct exposure of the epitrochlearis muscle to 0.5mmol/L AICAR or 1mmol/L caffeine, which activated p-AMPK increased both MCT1 and MCT4 mRNA levels. When pAMPK was inhibited by dantrolene, neither MCT1 nor MCT4 mRNA was increased.

CONCLUSION

These results suggest that acute exercise-induced increases in MCT1 and MCT4 mRNA expression may be possibly mediated by AMPK activation, at least in part in fast-twitch muscle.

Tripeptidyl peptidase II regulates sperm function by modulating intracellular Ca(2+) stores via the ryanodine receptor

Recent studies have identified Ca²⁺ stores in sperm cells; however, it is not clear whether these Ca²⁺ stores are functional and how they are mobilized. Here, in vitro and in vivo, we determined that tripeptidyl peptidase II antagonists strongly activated the cAMP/PKA signaling pathway that drives sperm capacitation-associated protein tyrosine phosphorylation. We demonstrated that in the absence of Ca²⁺, TPIII antagonists elevated the intracellular Ca²⁺ levels in sperm, resulting in a marked improvement in sperm movement, capacitation, acrosome reaction, and the in vitro fertilizing ability. This antagonist-induced release of intracellular Ca²⁺ could be blocked by the inhibitors of ryanodine receptors (RyRs) which are the main intracellular Ca²⁺ channels responsible for releasing stored Ca²⁺. Consistent with these results, indirect immunofluorescence assay using anti-RyR antibodies further validated the presence of RyR₃ in the acrosomal region of mature sperm. Thus, TPPII can regulate sperm maturation by modulating intracellular Ca²⁺ stores via the type 3 RyR.

Interleukin-6 prevents NMDA-induced neuronal death via Gp130 signaling-dependent IP3R inhibition

OBJECTIVE

To reveal the involvement of inositol 1,4,5-trisphosphate receptors (IP3R) and ryanodine receptors (RyR) in IL-6 prevention from neuronal apoptosis and necrosis induced by N-methyl-D-aspartate (NMDA).

METHODS

Cerebellar granule neurons (CGNs) from 8-day-old rats were exposed to IL-6 for 8 days and then stimulated with NMDA for 30 min. The 2-aminoethoxydiphenyl borate (2-APB) and dantrolene (DAN) were used to antagonize IP3R and RyR, respectively. Anti-gp130 monoclonal antibody (mAb) was employed to neutralize gp130, a 130-kDa signal-transducing β-subunit of IL-6 receptor complex. Neuronal apoptosis and necrosis were determined by TUNEL, fluorometric caspase-3 enzyme activity, annexin V-FITC/PI staining and ELISA. Western blot and real-time PCR measured IP3R1 and RyR2 expression, respectively.

RESULTS

IL-6 prevented the elevation of TUNEL-positive cells and caspase-3 expression and activity, and also suppressed the increase in annexin V-FITC/PI-positive cells and DNA- and histone-associated nucleosomes in cultured CGNs evoked by NMDA. These anti-apoptotic and anti-necrotic effects of IL-6 were larger on DAN-treated cells than on 2-APB-exposed neurons, since 2-APB treatment alone significantly inhibited the neuronal apoptosis and necrosis but DAN exposure alone did not alter the apoptosis and necrosis induced by NMDA. In support of these results, IL-6 downregulated IP3R1 but did not affect RyR2 expression. All these IL-6 effects were blocked by anti-gp130 mAb.

CONCLUSION

IL-6 prevention from NMDA-triggered Ca2+-induced Ca2+ release-mediated apoptosis and necrosis in CGNs depends on the inhibition of IP3R channel opening and expression rather than on RyR activity. IL-6 receptor-coupled gp130 signaling mediates this neuroprotection of IL-6 resistance to neuronal apoptosis and necrosis.

Vestibular-mediated synaptic inputs and pathways to sympathetic preganglionic neurons in the neonatal mouse

To assess when vestibulosympathetic projections become functional postnatally, and to establish a preparation in which vestibulosympathetic circuitry can be characterized more precisely, we used an optical approach to record VIIIth nerve-evoked synaptic inputs to thoracic sympathetic preganglionic neurons (SPNs) in newborn mice. Stimulation of the VIIIth nerve was performed in an isolated brainstem-spinal cord preparation after retrogradely labelling with the fluorescent calcium indicator Calcium Green 1-conjugated dextran amine, the SPNs and the somatic motoneurons (MNs) in the thoracic (T) segments T2, 4, 6, 8, 10 and 12. Synaptically mediated calcium responses could be visualized and recorded in individual SPNs and MNs, and analysed with respect to latency, temporal pattern, magnitude and synaptic pharmacology. VIIIth nerve stimulation evoked responses in all SPNs and MNs investigated. The SPN responses had onset latencies from 90 to 200 ms, compared with much shorter latencies in MNs, and were completely abolished by mephenesin, a drug that preferentially reduces polysynaptic over monosynaptic transmission. Bicuculline and picrotoxin, but not strychnine, increased the magnitudes of the SPN responses without changing the onset latencies, suggesting a convergence of concomitant excitatory and inhibitory synaptic inputs. Lesions strategically placed to test the involvement of direct vestibulospinal pathways versus indirect pathways within the brainstem showed that vestibulosympathetic inputs in the neonate are mediated predominantly, if not exclusively, by the latter. Thus, already at birth, synaptic connections in the vestibulosympathetic reflex are functional and require the involvement of the ventrolateral medulla as in adult mammals.

HOCl causes necrotic cell death in human monocyte derived macrophages through calcium dependent calpain activation

The abundance of dead macrophages in close proximity to HOCl-modified proteins in advanced atherosclerotic plaques implicates HOCl in the killing of macrophages and the formation of the necrotic core region. The mechanism of HOCl mediated death of macrophages was unknown, so using human monocyte derived macrophages (HMDM) we here have shown that HOCl causes a rapid necrotic cell death characterized by loss of MTT reduction, cellular ATP and cell lysis without caspase-3 activation in HMDM cells. The HOCl causes a rise in cytosolic calcium level via the plasma membrane L- and T-type calcium channels and endoplasmic reticulum RyR channel. Blocking of the calcium channels or the addition of calpain inhibitors prevents the HOCl mediated loss of mitochondrial potential, lysosome failure and HMDM cell death. Blocking MPT-pore formation with cyclosporin A also prevents the loss of mitochondrial membrane potential, lysosomal destabilization and HMDM cell death. Blocking the calcium mitochondrial uniporter with ruthenium red also blocks the loss of mitochondrial potential but only at high concentrations. HOCl appears to cause HMDM cell death through destabilization of cytosolic calcium control resulting in the failure of both the mitochondria and lysosomes.

Effects of Chlorpromazine, Promazine, Diethazine, Reserpine, Hydroxyzine, and Morphine upon Some mono- and Polysynaptic Motor Reflexes

The effects of chlorpromazine, promazine, diethazine, reserpine, hydroxyzine and morphine on some mono- and polysynaptic motor reflexes have been investigated in intact, spinal and decerebrate cats and rabbits. Chlorpromazine, promazine, reserpine and hydroxyzine selectively depress the monosynaptic spinal reflexes (knee jerk) of the intact animals. Polysynaptic reflexes (linguo-mandibular and crossed extensor) are slightly affected. In both cats and rabbits the brain of which was disconnected from the spinal cord by surgical sections at different levels, the inhibitory action of these drugs disappears. Morphine and diethazine, on the contrary, selectively depress the polysynaptic reflexes (linguo-mandibular) and in a minor degree the monosynaptic ones (knee jerk): this action is retained in spinal animals. These findings are discussed and related to other pharmacological properties of the compounds.

Spasmolytic Esters of N-Substituted α-Aminophenylacetic Acids

A series of alkyl and cycloalkyl esters of α-(2-pyrrolidin-1′-ylethyl- amino-), α-(2-piperidinoethylamino)- and α-(2-diethylaminoethyl- amino)-phenylacetic acid has been synthesised and examined for spasmolytic activity. The isopentyl- and cyclohexyl esters of α-(2-pyrrolidin-1′-ylethylamino)phenylacetic acid are new compounds possessing spasmolytic properties greater than papaverine and, in addition, 1 per cent and 4 per cent respectively of the antimuscarine activity of atropine as measured on the guinea pig ileum.

A Note on the Action of Gallamine on Isolated Rabbit Auricles

The action of gallamine triethiodide on the effects of methacholine and acetylcholine on isolated spontaneously beating rabbit auricles in oxygenated mammalian Ringer's solution at 30° has been investigated. Gallamine blocked the effects of both drugs. The effects of gallamine were similar to those of atropine, but gallamine was weaker and was more readily removed by washing.

Comparison of the therapeutic effectiveness of a dantrolene sodium solution and a novel nanocrystalline suspension of dantrolene sodium in malignant hyperthermia normal and susceptible pigs

BACKGROUND AND OBJECTIVE

Stopping trigger agents and prompt administration of dantrolene are the cornerstones of treatment of malignant hyperthermia. However, significant time is lost in treatment of the condition because of the cumbersome preparation and administration of the commercially available dantrolene sodium for injection. A potential improvement has become available in the form of a novel nanocrystalline dantrolene sodium suspension (DSS), which is 150 times more concentrated (50 mg ml(-1)) than the standard dantrolene sodium solution (0.33 mg ml(-1)). The aims of this study were to measure the effects of DSS on clinical and laboratory variables in malignant hyperthermia normal pigs and to compare the therapeutic management and clinical effectiveness of DSS with standard dantrolene sodium in a fulminant malignant hyperthermia crisis in susceptible pigs. The pig model is a well accepted method of studying the malignant hyperthermia crisis and is an ideal way to evaluate the variables of interest in this study.

METHODS

Seven malignant hyperthermia normal and 10 malignant hyperthermia susceptible pigs were studied. Malignant hyperthermia susceptible pigs (body weight approximately 24 kg) were allocated to a dantrolene sodium group or a DSS group. After induction of anaesthesia, a 22-gauge catheter was placed in an ear vein and trigger-free anaesthesia was performed. After achieving stable conditions, administration of halothane was started with 0.1% and then 0.15%. Halothane was discontinued after the administration of 0.2% (malignant hyperthermia normal pigs) or when a fulminant malignant hyperthermia crisis was achieved (malignant hyperthermia susceptible pigs). After halothane was discontinued, FIO2 was set to 1.0, respiratory minute volume was doubled and sodium bicarbonate 2 mmol kg(-1) was administered. The time required to prepare and administer each formulation was measured. To simulate the administration of the substances under typical clinical conditions for a child weighing approximately 24 kg, dantrolene sodium (5 mg kg(-1)) or DSS (5 mg kg(-1)) was prepared and injected via the intravenous 22-gauge cannula. Bolus administrations of dantrolene sodium or DSS were repeated after 24 min.

RESULTS

Arterial pH, arterial pCO2, mean arterial pressure and arterial lactate concentration remained stable during the experiment with DSS in malignant hyperthermia normal pigs. A significant decrease in cardiac index and increases in systemic vascular resistance and serum potassium concentration occurred after administration of DSS. In all malignant hyperthermia susceptible animals, the inhaled administration of halothane 0.15% led to a fulminant malignant hyperthermia crisis. The therapeutic regimens with administration of dantrolene sodium or DSS were successful in treating the malignant hyperthermia crisis in all animals. The course of the malignant hyperthermia crisis and the therapeutic effects of dantrolene sodium or DSS were comparable in the two groups. The time needed to prepare DSS for administration was significantly shorter (51 ± 9 s) compared to dantrolene sodium (860 ± 202 s). The time taken to inject DSS (4 ± 2 s) was significantly shorter than for dantrolene sodium (472 ± 51 s).

CONCLUSION

The therapeutic action of DSS in a malignant hyperthermia crisis in pigs was effective and comparable to that of standard dantrolene sodium. However, preparation and administration of DSS were significantly faster, which may offer a clinically significant advantage in the treatment of a fulminant malignant hyperthermia crisis and may result in a reduction in stress for the anaesthesia team.

A phase IV observational multi-centre, open-label study on efficacy and safety of tolperisone 150 mg in patients with painful muscle spasm associated with degenerative or inflammatory diseases of the musculoskeletal system

AIMS

To generate real world clinical data on efficacy and tolerability of tolperisone 150 mg in painful muscle spasms in Indian population.

SETTINGS AND DESIGN

Prospective, open-labelled, non-comparative, multi-centre observational, Post Marketing surveillance study conducted at 174 participating orthopaedic care centres across India

METHODS AND MATERIAL

Nine hundred and twenty adult patients having painful muscle spasm associated with degenerative or inflammatory conditions were enrolled who received tolperisone 150 mg thrice daily orally for 7 days. Assessment of primary efficacy (muscle spasm) was done by (0-3) Likert scale. Adverse events were monitored for safety and global efficacy assessment was done by clinicians and patients at the end of study period.

RESULTS

Significant improvements from baseline (p < 0.0001) in scores for muscle tone, mobility & pain were seen on days 3 & 7. At the end of study there was a significant reduction in scores by more than 80% from baseline. A subgroup analysis revealed no statistical difference in the scores in patients receiving Non-Steroidal AntiInflammatory Drug (NSAID) as compared to those receiving Tolperisone alone suggesting that Tolperisone alone could be offered to patients with painful muscle spasm who are intolerant to NSAIDs or in whom NSAIDs are contraindicated. Tolperisone was well tolerated with no sedation reported by any patient during study period. The incidence of common adverse effects like nausea, gastric irritation was less than 2%.

CONCLUSIONS

Tolperisone is a safe, effective and non sedative alternative in management of acute painful spasm conditions associated with degenerative or inflammatory diseases of the musculoskeletal system. Key Messages: Tolperisone is a skeletal muscle relaxant without concomitant sedation or withdrawal phenomena. In this open-labelled, non-comparative, prospective study tolperisone was proved to be a safe & effective alternative to skeletal muscle relaxants in the management of acute painful spasm conditions associated with degenerative or inflammatory diseases of the musculoskeletal system.

Impaired hippocampal Ca2+ homeostasis and concomitant K+ channel dysfunction in a mouse model of Rett syndrome during anoxia

Methyl-CpG-binding protein 2 (MeCP2) deficiency causes Rett syndrome (RTT), a neurodevelopmental disorder characterized by severe cognitive impairment, synaptic dysfunction, and hyperexcitability. Previously we reported that the hippocampus of MeCP2-deficient mice (Mecp2(-/y)), a mouse model for RTT, is more susceptible to hypoxia. To identify the underlying mechanisms we now focused on the anoxic responses of wildtype (WT) and Mecp2(-/y) CA1 neurons in acute hippocampal slices. Intracellular recordings revealed that Mecp2(-/y) neurons show only reduced or no hyperpolarizations early during cyanide-induced anoxia, suggesting potassium channel (K(+) channel) dysfunction. Blocking adenosine-5'-triphosphate-sensitive K(+) channels (K(ATP-)) and big-conductance Ca(2+)-activated K(+) channels (BK-channels) did not affect the early anoxic hyperpolarization in either genotype. However, blocking Ca(2+) release from the endoplasmic reticulum almost abolished the anoxic hyperpolarizations in Mecp2(-/y) neurons. Single-channel recordings confirmed that neither K(ATP)- nor BK-channels are the sole mediators of the early anoxic hyperpolarization. Instead, anoxia Ca(2+)-dependently activated various small/intermediate-conductance K(+) channels in WT neurons, which was less evident in Mecp2(-/y) neurons. Yet, pharmacologically increasing the Ca(2+) sensitivity of small/intermediate-conductance K(Ca) channels fully restored the anoxic hyperpolarization in Mecp2(-/y) neurons. Furthermore, Ca(2+) imaging unveiled lower intracellular Ca(2+) levels in resting Mecp2(-/y) neurons and reduced anoxic Ca(2+) transients with diminished Ca(2+) release from intracellular stores. In conclusion, the enhanced hypoxia susceptibility of Mecp2(-/y) hippocampus is primarily associated with disturbed Ca(2+) homeostasis and diminished Ca(2+) rises during anoxia. This secondarily attenuates the activation of K(Ca) channels and thereby increases the hypoxia susceptibility of Mecp2(-/y) neuronal networks. Since cytosolic Ca(2+) levels also determine neuronal excitability and synaptic plasticity, Ca(2+) homeostasis may constitute a promising target for pharmacotherapy in RTT.

Anaesthesia for endoscopic sinus surgery

Endoscopic sinus surgery is commonly performed and has a low risk of major complications. Intraoperative bleeding impairs surgical conditions and increases the risk of complications. Remifentanil appears to produce better surgical conditions than other opioid analgesics, and total intravenous anaesthesia with propofol may provide superior conditions to a volatile-based technique. Moderate hypotension with intraoperative beta blockade is associated with better operating conditions than when vasodilating agents are used. Tight control of CO(2) does not affect the surgical view. The use of a laryngeal mask may be associated with improved surgical conditions and a smoother emergence. It provides airway protection equivalent to that provided by an endotracheal tube in well-selected patients, but offers less protection from gastric regurgitation. Post-operatively, multimodal oral analgesia provides good pain relief, while long-acting local anaesthetics have been shown not to improve analgesia.

Assessment of the effect of the use of laser light or dantrolene on facial muscle under occlusal wear: a Raman spectroscopic study in a rodent model

OBJECTIVE

The aim of the present study was to use Raman spectroscopy to measure levels of CaPi in muscles under occlusal wear and treated with laser phototherapy (LPT) or muscle-relaxant therapy or both on rodents.

BACKGROUND

The etiology of temporomandibular disorders is multifactorial. Malocclusion may influence the masticatory muscles, causing fatigue. A major type of fatigue is the metabolic, caused by the increased accumulation of metabolites such as inorganic phosphate. Raman spectroscopy allows nondestructive analysis of the biochemical composition of tissues.

METHODS

The 30 male Wistar rats were randomly divided into three groups: occlusal wear (G-1), occlusal wear + LPT (G-2), and occlusal wear + muscle relaxant (G-3). Ten untreated animals were used for baseline data. Under intraperitoneal general anesthesia, animals of groups 1, 2, and 3 had unilateral amputation of molar cusps to simulate an occlusal-wear situation. The masseter muscle of G-2 received LPT (lambda830 nm, 4 J/cm(2), 40 mW, phi approximately 2 mm) after the procedure and repeated every other day for 14-30 days. Animals of G-3 were treated with a daily injection of dantrolene (2.5 mg/kg in 0.5 ml of H(2)O) beginning 24 h after cusp removal. Animals were killed with an overdose of general anesthetics at days 14 and 30 after cusps removal, and the ipsilateral masseter muscle was excised and divided into two parts. One part was routinely processed and underwent histologic analysis; the other was kept in liquid nitrogen for Raman spectroscopy. The mean value of the intensity of the peak 958 per centimeter was determined.

RESULTS

No morphologic changes were seen. Raman analysis showed significantly less Raman intensity in the laser group at 30 days (p < 0.01).

CONCLUSION

Occlusal wear did not caused morphologic alterations in the masseter muscle but resulted in changes of the levels of CaP(i) that were less compromising when the laser light was used.

[Effect of neurogenic inactivity on posttetanic responses of rat fast muscle]

At a short-term tetanic stimulation of fast muscle in response to subsequent single stimulation there is recorded a temporary increase of the strength of single contractions that returns to the initial background after 6--10 min. This phenomenon is called posttetanic potentiation (PTP) and is recorded only in fast muscles. The goal of the present work was a study of effect of motor innervation on the course of PTP in rat m. extensor digitorum longus (m. Edl). It has been established that the first signs of effect of motor denervation on the PTP course after section of sciatic nerve in the area of popliteal fossa are recorded as early as at the 4th day after denervation and are expressed in a decrease of strength of single contractions after cessation of tetanic stimulation. These changes reach its maximum at the 14--15th day after denervation when effect of PTP in denervation muscle does not appear at all. Pharmacological analysis of the studied phenomenon has shown that dantrolene (10 microM) suppresses amplitude of the single contraction, but does not prevent the appearance of PTP in intact muscle. In the denervation of m. Edl, instead of the appearance of PTP, after a brief slight increase, a gradual decrease of the strength of contraction is recorded. Thus, it can be concluded that no significant PTP changes are present under action of dantrolene. It has been established that after the 10-min muscle incubation in Ringer's solution with caffeine (4 mM), strength of the single contraction in intact and denervated muscles increases by approximately equal value. Tetanization of intact muscle increases strength of the single contraction approximately by 7 % more than this occurs after incubation with caffeine, i. e., this substance reduces the capability of muscle for the appearance of PTP. On denervation muscle, caffeine increases strength of singly contraction, but does not potentiate development of PTP. The obtained data allow concluding about the existence of different mechanisms underlying the pretetatnic contraction and posttetanic potentiation of the single contraction. The main difference between two types of contractions can be recruiting of additional DICR-channels in the process of contraction under conditions of PTP.

Insights on novel biologically active natural products: 7-isopentenyloxycoumarin

7-Isopentenyloxycoumarin is a prenyloxyphenylpropanoid derivative found in low concentration in a restricted number of plant families (Apiaceae, Asteraceae, and Rutaceae). Synthetic schemes were recently developed enabling sufficient quantities of the title coumarin to be obtained in order to evidence its valuable biological effects, mainly as an anti-cancer agent. The aim of this review is to examine the phytochemical and pharmacological properties of this compound.

Functional role of neuroendocrine-specific protein-like 1 in membrane translocation of GLUT4

OBJECTIVE

In skeletal muscles, dantrolene inhibits the exercise-induced membrane translocation of GLUT4. It has been postulated that the inhibitory action of dantrolene on Ca(2+) release from the sarcoplasmic reticulum (SR) causes inhibition of exercise-induced glucose uptake; however, the precise mechanism has not been adequately studied.

RESEARCH DESIGN AND METHODS

We discovered that dantrolene can bind to skeletal-type neuroendocrine-specific protein-like 1 (sk-NSPl1) with photoreactive dantrolene derivatives. In sk-NSPl1-deficient muscles, we examined the change in glucose uptake and the membrane translocation of GLUT4. In addition, we examined the change in blood glucose and also measured the glycogen level in both isolated and in situ skeletal muscles after electrical stimulation using our mutant mouse.

RESULTS

In sk-NSPl1-deficient muscles, exercise-induced glucose uptake was totally abolished with no change in insulin-induced glucose uptake. The Ca(2+) release mechanism and its inhibition by dantrolene were completely preserved in these muscles. The expression of GLUT4 in the mutant muscles also appeared unchanged. Confocal imaging and results using the membrane isolation method showed that exercise/contraction did not enhance GLUT4 translocation in these sk-NSPl1-deficient muscles under conditions of adequate muscle glycogen consumption. The blood glucose level in normal mice was reduced by electrical stimulation of the hind limbs, but that in mutant mice was unchanged.

CONCLUSIONS

sk-NSPl1 is a novel dantrolene receptor that plays an important role in membrane translocation of GLUT4 induced by contraction/exercise. The 23-kDa sk-NSPl1 may also be involved in the regulation of glucose levels in the whole body.

Interactions of Magnolia and Ziziphus extracts with selected central nervous system receptors

ETHNOPHARMACOLOGICAL RELEVANCE

Magnolia officinalis Rehder and Wilson [Magnoliaceae] bark and Ziziphus spinosa (Buhge) Hu ex. Chen. [Fam. Rhamnaceae] seed have a history of use in traditional Asian medicine for mild anxiety, nervousness and sleep-related problems.

AIM OF THE STUDY

To identify pharmacological targets, extracts of Magnolia officinalis (ME), Ziziphus spinosa (ZE), and a proprietary fixed combination (MZE) were tested for affinity with central nervous system receptors associated with relaxation and sleep.

METHODS

In vitro radioligand binding and cellular functional assays were conducted on: adenosine A(1), dopamine (transporter, D(1), D(2S), D(3), D(4.4) and D(5)), serotonin (transporter, 5-HT(1A), 5-HT(1B), 5-HT(4e), 5-HT(6) and 5-HT(7)) and the GABA benzodiazepine receptor.

RESULTS

Interactions were demonstrated with the adenosine A(1) receptor, dopamine transporter and dopamine D(5) receptor (antagonist activity), serotonin receptors (5-HT(1B) and 5-HT(6) antagonist activity) and the GABA benzodiazepine receptor at a concentration of 100 microg/ml or lower. ME had an affinity with adenosine A(1) (K(i) of 9.2+/-1.1 microg/ml) and potentiated the GABA activated chloride current at the benzodiazepine subunits of the GABA receptor (maximum effect at 50 microg/ml). ME had a modest antagonist action with 5-HT(6) and ZE with the 5-HT(1B) receptor.

CONCLUSION

The interactions in the receptor binding models are consistent with the traditional anxiolytic and sleep-inducing activities of Magnolia officinalis bark and Ziziphus spinosa seed.

Uniaxial cyclic stretch increases glucose uptake into C2C12 myotubes through a signaling pathway independent of insulin-like growth factor I

Insulin-like growth factor I (IGF-I), an autocrine/paracrine growth factor involved in myogenesis, has rapid effects on muscle metabolism. In a manner analogous to insulin and mechanical stimuli such as stretch, IGF-I stimulates glucose transport through recruitment of glucose transporters to surface membranes in skeletal muscles. It is known that IGF-I is secreted from skeletal muscle cells in response to stretch. Therefore, we examined whether IGF-I is involved in the mechanism by which mechanical stretch regulates glucose transport using cultured C2C12 myotubes. IGF-I increased 2-deoxy- D-glucose (2-DG) uptake, and this created an additive effect with mechanical stretch, suggesting that these stimuli enhance glucose transport through different mechanisms. In fact, IGF-I-stimulated 2-DG uptake was not blocked by dantrolene (an inhibitor of Ca (2+)release from sarcoplasmic reticulum), whereas the stretch-stimulated effect was abolished. Conversely, the IGF-I-stimulated 2-DG uptake was prevented by phosphatidylinositol 3-kinase inhibitor wortmannin, which did not prevent the stretch-stimulated 2-DG uptake. In addition, experiments using media conditioned by stretched myotubes indicated that a mechanically induced release of locally acting autocrine/paracrine growth factors was not sufficient for induction of 2-DG uptake. Thus, our results demonstrate that mechanical stretch signaling for glucose transport is independent of the mechanism through which IGF-I increases this transport.

Baclofen reduces ethanol intake in high-alcohol-drinking University of Chile bibulous rats

ABSTRACT Treatment with gamma-aminobutiric acid (GABA(B)) receptor agonist, +/-baclofen, has been shown to reduce ethanol intake in selectively bred Sardinian alcohol-preferring rats. The general goal of the present study was to characterize the high ethanol consumption high-alcohol-drinking University of Chile bibulous (UChB) rats with regard to the anti-alcohol effect of GABA(B) receptor stimulation. UChB rats were treated with the more active enantiomer of baclofen [R(+)-baclofen; at a dose of 1.0, 2.0 or 3.0 mg/kg] administered intraperitoneally once daily for four consecutive days or a single dose. When comparing ethanol and saccharin consumption in a free-choice regimen with unlimited access 24 hours/day, the dose of baclofen required to attenuate ethanol consumption significantly was 1.0 mg/kg administered once a day for three consecutive days while the dose that was sufficient to affect saccharin consumption significantly was 2.0 mg/kg, indicating that baclofen was more potent in reducing ethanol intake by UChB rats than reducing saccharin consumption. The reduction of ethanol or saccharin intake can not be attributed to baclofen-induced motor impairment, since baclofen (1.0, 2.0 or 3.0 mg/kg) did not alter spontaneous locomotor activity in UChB rats. Baclofen dose-dependently suppressed the motor activity stimulated by ethanol administration, a phenomenon mediated by activation of the mesolimbic dopamine system. In conclusion, these results showed that the activation of GABA(B) receptor by R(+)-baclofen reduced ethanol and saccharin consumption, as well as ethanol-induced motor stimulation, implicating the GABA(B) receptor in the neural substrates mediating effects that sustain voluntary ethanol in take in UChB rats.

A practical overview of tizanidine use for spasticity secondary to multiple sclerosis, stroke, and spinal cord injury

OBJECTIVE

Tizanidine is an imidazoline central alpha(2)-adrenoceptor agonist widely used to manage spasticity secondary to conditions such as multiple sclerosis (MS), stroke, and spinal cord injury (SCI). While there is widespread use of tizanidine in clinical practice, little practical information is available to assist prescribers with the effective use of tizanidine for spasticity management. The aim of this review is to provide an up-to-date overview of tizanidine and its use in the management of spasticity associated with acquired (SCI), static (stroke), and progressive neurological (MS) diseases.

SCOPE

An unfiltered literature search of the term 'tizanidine' was undertaken on the Medline database resulting in 311 papers. As the review focused on tizanidine clinical pharmacokinetics, efficacy, and tolerability, with comparisons limited to the oral antispastic agents baclofen, diazepam, and dantrolene, 53 articles were selected for detailed assessment.

FINDINGS

Tizanidine, an alpha(2)-adrenoceptor agonist, is a short-acting drug with larger interpatient variability, and linear pharmacokinetics that is dosage form-dependent. Clinical trials have demonstrated that the efficacy of tizanidine is comparable to that of baclofen or diazepam with global tolerability data favoring tizanidine. A clinical case presentation demonstrated the effective use of tizanidine in combination with baclofen as a logical avenue for improved spasticity control.

CONCLUSIONS

There is a large body of evidence for the effective use of tizanidine monotherapy in the management of spasticity. A case study demonstrates that combination therapy can effectively control spasticity while better managing dose-dependent adverse events, although additional studies need to be performed to confirm these results.

[Analgesia, sedation and relaxation in the child with mechanical ventilation]

The basic concepts of sedation and analgesia and the tools to asses the level of sedation and analgesia are review. The different methods of sedation and the non pharmacological interventions are described. Sedatives, analgesics and muscle relaxants, their pharmacodynamics and pharmacokinetics in children, their indications in specific situations (intubation, pain control, sedation and neuromuscular blocking) are reviewed. The etiology of patient-ventilator asynchrony in ventilated children and how to treat it are analyzed, giving guides of how to adapt sedation to the level of mechanical ventilation therapy. Finally, general recommendations are given for the analgesia and sedation in mechanically ventilated children.

[The use of baclosan in the complex therapy of muscle-tonic and myofascial pain syndromes in patients with dorsopathy]

Baclosan (baclofen), a GABA analogue, has been used in the treatment of 20 patients, aged 20-56 years, with a pain syndrome in dorsopathy of lumbar spine. Baclosan has been administered in the increasing dosages (from 10 mg to 30 mg per day) for 4 weeks in conjunction with traditional therapy (symptomatic pharmacotherapy, physiotherapy, reflexotherapy etc).The control group consisted of 10 patients who received only basic therapy (without baclosan). Patient's status has been measured clinically and with several scales. The results obtained allow to conclude that baclosan exerts a positive effect in the pain syndrome caused by dorsopathy. Its inclusion to the complex therapy reduces both the pain intensity and the degree of muscle-tonic tension as well as improves the motor function and emotional state of patients.

Intramuscular injection of sevoflurane detects malignant hyperthermia predisposition in susceptible pigs

BACKGROUND

The authors hypothesized that intramuscular sevoflurane injection allows diagnostic differentiation between malignant hyperthermia-susceptible (MHS) and -nonsusceptible (MHN) pigs by measurement of intramuscular lactate and carbon dioxide partial pressure (PCO2), and that dantrolene reduces the sevoflurane-induced PCO2 increase.

METHODS

With approval of the local animal care committee, microdialysis probes with attached microtubing for sevoflurane injection were placed in the adductor muscles of nine MHS and six MHN pigs, and PCO2 probes with microtubing were positioned in the triceps muscle of eight MHS and six MHN pigs. After equilibration, sevoflurane boluses at different concentrations and a sevoflurane-dantrolene bolus were injected synchronously. Lactate, pyruvate, and glucose as well as PCO2 were measured spectrophotometrically, and the rate of PCO2 increase was calculated.

RESULTS

Intramuscular sevoflurane injection increased local lactate and PCO2 dose dependently, and significantly higher in MHS than in MHN pigs. Measurement of the rate of PCO2 increase allowed a distinct differentiation between single MHS and MHN pigs. No significant increase in PCO2 was found with sevoflurane and dantrolene.

CONCLUSIONS

Local sevoflurane induces a hypermetabolic reaction measured by PCO2 and lactate increases. The reduced PCO2 increase in MHS after sevoflurane and dantrolene injection is likely to be a result of the sevoflurane-mediated calcium release and its antagonism by dantrolene. Sevoflurane may be useful for a less invasive diagnostic test for malignant hyperthermia in humans.