Anticonvulsant effects of phencynonate hydrochloride and other anticholinergic drugs in soman poisoning: neurochemical mechanisms

Neurotoxicity evoked by organophosphates and available countermeasures

Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABA_AR by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved.

Phencynonate hydrochloride exerts antidepressant effects by regulating the dendritic spine density and altering glutamate receptor expression

Phencynonate hydrochloride (PCH) is a drug that crosses the blood-brain barrier. Cellular experiments confirmed that PCH protects against glutamate toxicity and causes only weak central inhibition and limited side effects. As shown in our previous studies, PCH alleviates depression-like behaviours induced by chronic unpredictable mild stress (CUMS). Here we administered PCH at three different doses (4, 8 and 16 mg/kg) to male rats for two continuous days after CUMS and conducted behavioural tests to assess the dose-dependent antidepressant effects of PCH and its effects on the neuroplasticity in the hippocampus and medial prefrontal cortex (mPFC). Meanwhile, we measured the spine density and expression of related proteins to illustrate the mechanism of PCH. PCH treatment (8 mg/kg) significantly alleviated depression-like behaviours induced by CUMS. All doses of PCH treatment reversed the spine loss in prelimbic and CA3 regions induced by CUMS. Kalirin-7 expression was decreased in the hippocampus and mPFC of the CUMS group. The expression of the NR1 and NR2B subunits in the hippocampus, and NR2B in mPFC are increased by CUMS. PCH treatment (8 and 16 mg/kg) reversed all of these changes of Kalirin-7 in PFC and hippocampus, as well as NR1 and NR2B expression in the hippocampus. PCH is expected to be developed as a new type of rapid antidepressant. Its antidepressant effect may be closely related to the modulation of dendritic spine density in the prelimbic and CA3 regions and the regulation of Kalilin-7 and N-methyl-D-aspartic acid receptor levels in the hippocampus.

TRPV4 Regulates Soman-Induced Status Epilepticus and Secondary Brain Injury via NMDA Receptor and NLRP3 Inflammasome

Nerve agents are used in civil wars and terrorist attacks, posing a threat to public safety. Acute exposure to nerve agents such as soman (GD) causes serious brain damage, leading to death due to intense seizures induced by acetylcholinesterase inhibition and neuronal injury resulting from increased excitatory amino-acid levels and neuroinflammation. However, data on the anticonvulsant and neuroprotective efficacies of currently-used countermeasures are limited. Here, we evaluated the potential effects of transient receptor vanilloid 4 (TRPV4) in the treatment of soman-induced status epilepticus (SE) and secondary brain injury. We demonstrated that TRPV4 expression was markedly up-regulated in rat hippocampus after soman-induced seizures. Administration of the TRPV4 antagonist GSK2193874 prior to soman exposure significantly decreased the mortality rate in rats and reduced SE intensity. TRPV4-knockout mice also showed lower incidence of seizures and higher survival rates than wild-type mice following soman exposure. Further in vivo and in vitro experiments demonstrated that blocking TRPV4 prevented NMDA receptor-mediated glutamate excitotoxicity. The protein levels of the NLRP3 inflammasome complex and its downstream cytokines IL-1β and IL-18 increased in soman-exposed rat hippocampus. However, TRPV4 inhibition or deletion markedly reversed the activation of the NLRP3 inflammasome pathway. In conclusion, our study suggests that the blockade of TRPV4 protects against soman exposure and reduces brain injury following SE by decreasing NMDA receptor-mediated excitotoxicity and NLRP3-mediated neuroinflammation. To our knowledge, this is the first study regarding the "dual-switch" function of TRPV4 in the treatment of soman intoxication.

Penehyclidine hydrochloride alleviates lipopolysaccharide‑induced acute respiratory distress syndrome in cells via regulating autophagy‑related pathway

Acute progressive hypoxic respiratory failure caused by various predisposing factors is known as acute respiratory distress syndrome (ARDS). Although penehyclidine hydrochloride (PHC), an anticholinergic drug, is widely applied in clinical practice, the specific mechanisms underlying PHC in the treatment of ARDS are not completely understood. In the present study, BEAS-2B cells were treated with 10 ng/ml lipopolysaccharide (LPS) to establish an ARDS cell model and a rat model of acute lung injury (ALI). The influences of PHC and/or autophagy inhibitor (3-methyladenine (3-MA)) on the morphology, autophagy, proliferation and apoptosis of cells and tissues were evaluated using hematoxylin and eosin staining, Cell Counting Kit-8 assays, Hoechst staining, TUNEL staining, flow cytometry, immunofluorescence assays, ELISAs and scanning electron microscopy. The expression levels of apoptosis- and autophagy-related proteins were measured via western blotting. The results indicated that PHC enhanced proliferation and autophagy, and decreased apoptosis and the inflammatory response in LPS-induced BEAS-2B cells and ALI model rats. In addition, 3-MA reversed the effects of PHC on proliferation, inflammation, apoptosis and autophagy in LPS-induced BEAS-2B cells. Therefore, the present study suggested that PHC demonstrated a protective effect in LPS-induced ARDS by regulating an autophagy-related pathway.

Penehyclidine hydrochloride protects against anoxia/reoxygenation injury in cardiomyocytes through ATP-sensitive potassium channels, and the Akt/GSK-3β and Akt/mTOR signaling pathways

Penehyclidine hydrochloride (PHC) can protect against myocardial ischemia/reperfusion (I/R) injury. However, the possible mechanisms of PHC in anoxia/reoxygenation (A/R)-induced injury in H9c2 cells remain unclear. In the present study, H9c2 cells were pretreated with PI3K/Akt inhibitor LY294002, ATP-sensitive K⁺ (KATP) channel blocker 5-hydroxydecanoate (5-HD), PHC, or KATP channel opener diazoxide (DZ) before subjecting to A/R injury. Cell viability and cell apoptosis were determined by cell counting kit-8 assay and annexin V/PI assay, respectively. Myocardial injury was evaluated by measuring creatine kinase (CK) and lactate dehydrogenase (LDH) activities. Intracellular Ca²⁺ levels, reactive oxygen species (ROS) generation, mitochondrial membrane potential (ΔΨ_m ), and mitochondrial permeability transition pore (mPTP) were measured. The levels of cytoplasmic/mitochondrial cytochrome c (Cyt-C), Bax, Bcl-2, cleaved caspase-3, KATP channel subunits (Kir6.2 and SUR2A), and the members of the Akt/GSK-3β and Akt/mTOR signaling pathways were determined by western blotting. We found that PHC preconditioning alleviated A/R-induced cell injury by increasing cell viability, reducing CK and LDH activities, and inhibiting cell apoptosis. In addition, PHC preconditioning ameliorated intracellular Ca²⁺ overload and ROS production, accompanied by inhibition of both mPTP opening and Cyt-C release into cytoplasm, and maintenance of ΔΨ_m . Moreover, PHC preconditioning activated mitochondrial KATP channels, and modulated the Akt/GSK-3β and Akt/mTOR signaling pathways. Similar effects were observed upon treatment with DZ. Pretreatment with LY294002 or 5-HD blocked the beneficial effects of PHC. These results suggest that the protective effects of PHC preconditioning on A/R injury may be related to mitochondrial KATP channels, as well as the Akt/GSK-3β and Akt/mTOR signaling pathways.

Comparative effects of scopolamine and phencynonate on organophosphorus nerve agent-induced seizure activity, neuropathology and lethality

The efficacy of anticonvulsant therapies to stop seizure activities following organophosphorus nerve agents (NAs) has been documented as being time-dependent. We utilized the guinea pig NA-seizure model to compare the effectiveness of phencynonate (PCH) and scopolamine (SCP) when given at the early (at time of seizure onset) or late (40 min after seizure onset) phase of seizure progression. PCH possesses both anticholinergic and anti-NMDA activities, while SCP is a purely anti-muscarinic compound. Animals with cortical electrodes were pretreated with pyridostigmine bromide 30 min prior to exposure to a 2.0 x LD₅₀ subcutaneous dose of a NA (GA, GB, GD, GF, VR, or VX), followed one min later with atropine sulfate and 2-PAM. At either early or late phase, animals were treated with either PCH or SCP and the 24-h anticonvulsant ED₅₀ doses were determined. When administered at seizure onset, PCH, and SCP were both effective at terminating seizure activity against all NAs, with ED₅₀ values for SCP generally being lower. At the 40 min time, ED₅₀ values were obtained following GA, GD, GF, and VR challenges for SCP, but ED₅₀ value was obtained only following GD for PCH, indicating a superior efficacy of SCP. When seizure activity was controlled, a significant improvement in weight loss, neuropathology, and survival was observed, regardless of treatment or NA. Overall, these results demonstrate the differing efficacies of these two similarly structured anticholinergic compounds with delayed administration and warrant further investigation into the timing and mechanisms of the seizure maintenance phase in different animal models.

Penehyclidine effects the angiogenic potential of pulmonary microvascular endothelial cells

The present study sought to determine the pharmacological effects of penehyclidine, an anticholinergic agent, on the angiogenic capacity of pulmonary microvascular endothelial cells (PMVECs). In vitro Matrigel network formation assay, cell proliferation assay, cell-matrix adhesion assay, and wound-healing assay were performed in PMVECs with or without exposure to penehyclidine or, in some cases, glycopyrrolate or acetylcholine, over a concentration range. In addition, the phosphorylation state of Akt and ERK, as well as the endogenous level of mTOR and RICTOR were examined in PMVECs by Western blot following the cells exposure to penehyclidine or, for some proteins, glycopyrrolate or acetylcholine. Finally, Western blot for Akt phosphorylation and in vitro Matrigel network formation assay were performed in PMVECs following their exposure to penehyclidine with or without phosphoinositide 3-kinase (PI3K) inhibitor LY294002 or mTOR inhibitor torin-1. We found that, in PMVECs, penehyclidine affected the network formation and cell migration, but not proliferation or cell-matrix adhesion, in a concentration-specific manner, i.e., penehyclidine increased the network formation and cell migration at lower concentrations but increased these processes at higher concentrations. Coincidentally, we observed that penehyclidine concentration-specifically affected the phosphorylation state of Akt in PMVECs, i.e., increased Akt phosphorylation at lower concentrations and decreased it at higher concentrations. In contrast, glycopyrrolate was found straightly to decrease network formation and Akt phosphorylation in a concentration-dependent manner. Further, we demonstrated that PI3K or mTOR blockade abolished both the enhanced network formation and the increased Akt phosphorylation by penehyclidine. Hence, penehyclidine may differentially alter the angiogenic capacity of PMVECs through affecting the Akt signaling pathway downstream of PI3K and mTOR. Findings from this study suggest a unique pharmacological feature of penehyclidine, which may imply its clinical and therapeutic value in modulating angiogenesis.

Mechanism of penehyclidine hydrochloride on a dysmenorrhea rat model

Primary dysmenorrhea affects the quality of life in young women, particularly school and work performance. This study investigated the mechanisms of penehyclidine hydrochloride (PHC) efficacy on a rat model of primary dysmenorrhea. The model was induced by injecting both estradiol benzoate and oxytocin. Different doses of PHC were administrated intraperitoneally following estradiol benzoate administration. Writhing scores were assessed, and pathological changes of the uterus were observed via hematoxylin and eosin staining. Western blot and real-time PCR were used to evaluate the expression level of the M₃ receptor, both TLR₃ and TLR₄ in uterine tissue, and the level of Ca²⁺ was measured in uterine tissues. Writhing scores significantly decreased in the PHC treatment group compared to model, and PHC alleviated the occurrence of edema or necrosis in the uteri compared to model group. PHC can decrease the M₃ receptor, TLR₃ , TLR₄ expression, and the Ca²⁺ level compared to the model group. PHC is a potential candidate for the future treatment of primary dysmenorrhea due to its ability to attenuate muscarinic receptors and TLRs. Preclinical Research & Development.

Pleiotropic effects and pharmacological properties of penehyclidine hydrochloride

Background

Penehyclidine hydrochloride (PHC) is an anticholinergic drug manufactured in China. It is used widely in clinics as a reversal agent in cases of organic phosphorus poisoning and as a preanesthetic medication. Compared with other anticholinergic agents, PHC confers substantial advantages. Here, in this review, we focus on its important clinical effects for organic phosphorus poisoning, preanesthetic medication, and the protective effects on certain visceral organs.

Materials and methods

Our bibliographic sources include the PubMed and China National Knowledge Infrastructure (CNKI) databases, updated in March 2018. To assess the data in detail, we used the search terms “penehyclidine hydrochloride,” “preanesthetic medication,” and “organic phosphorus.” Papers were restricted to those published in the English and Chinese languages, and to “paper” and “review” as the document type.

Results

PHC can effectively antagonize the symptoms of central and peripheral poisoning caused by organophosphorus poisoning. As a preanesthetic medication, it can not only effectively reduce mucus secretion and vascular infiltration but can also relax airway smooth muscles, dilate bronchioles in pulmonary conditions such as bronchiectasis, and increase pulmonary dynamic compliance. It can also prevent reflexive actions of the vagus nerve caused by excessive acetylcholine release such as abnormal airway contraction. Furthermore, it can strengthen sedation, bidirectionally regulate heart rate, and effectively inhibit respiratory secretions. In recent studies, PHC was shown to also have protective effects on various organs, such as the heart, lungs, brain, kidneys, intestines, and liver.

Conclusion

PHC has beneficial pharmacological properties used in the treatment of organophosphorus poisoning and as a preanesthetic medication for its few side effects. It also has protective effects on multiple organs, suggesting that PHC has extensive clinical application value which is worth further research. This review should be of help to those intending to research these topics further.

Regulation of VDAC1 contributes to the cardioprotective effects of penehyclidine hydrochloride during myocardial ischemia/reperfusion

Penehyclidine hydrochloride (PHC) preconditioning can alleviate myocardial ischemia/reperfusion (I/R) injury and inhibits the upregulation of voltage-dependent anion channel 1 (VDAC1) during I/R. To validate that VDAC1 is a bona fide target of PHC for the protection against myocardial I/R injury, VDAC1 expression construct was delivered by lentiviruses into rat left ventricular myocardium before PHC preconditioning and myocardial I/R. Overexpression of VDAC1 exacerbated cardiac dysfunction and myocardial injury following I/R, and abolished the cardioprotective effect of PHC during I/R injury. Moreover, VDAC1 overexpression with myocardial I/R further increased cytochrome c release from mitochondria to cytoplasm, elevated the levels of cleaved caspase-3 and Bax, and decreased the level of Bcl-2 as compared with I/R alone, and PHC-mediated inhibition of mitochondria-dependent apoptosis during myocardial I/R was abolished by VDAC1 overexpression. In addition, VDAC1 was overexpressed in H9c2 cardiomyocytes undergoing anoxia/reoxygenation (A/R) with or without PHC pretreatment. The in vitro results showed that overexpression of VDAC1 further reduced mitochondrial membrane potential, increased mitochondrial membrane permeability and enhanced mitochondria-dependent apoptosis in H9c2 cells after A/R, and VDAC1 overexpression abrogated the protective effect of PHC on the mitochondrial function and integrity during A/R. In conclusion, exogenous overexpression of VDAC1 during myocardial I/R inhibits the cardioprotective effects of PHC. These effects may be associated with the suppression of VDAC1 expression.

Penehyclidine hydrochloride inhibits TLR4 signaling and inflammation, and attenuates blunt chest trauma and hemorrhagic shock-induced acute lung injury in rats

Blunt chest trauma with hemorrhagic shock (THS) frequently induces pulmonary inflammation that leads to acute lung injury (ALI). Penehyclidine hydrochloride (PHC) possesses anti‑inflammatory properties that may attenuate the systemic inflammatory response. The present study aimed to evaluate the molecular mechanism of PHC in modifying THS‑induced ALI in rats. Rats underwent either THS or a sham procedure. At 6 h subsequent to blunt chest trauma, arterial blood was drawn for blood gas and pro‑inflammatory factors analyses, and lung tissue samples were collected to examine pulmonary histopathological alterations, the wet/dry weight ratio, myeloperoxidase activity, and the protein expression levels of Toll-like receptor 4 (TLR4), phosphorylated (p‑)p38 mitogen‑activated protein kinase (MAPK), nuclear factor (NF)‑κB and activator protein‑1 (AP‑1). THS caused significant reductions in heart rate and mean arterial blood pressure, and was associated with significant increases in tumor necrosis factor‑α, interleukin (IL)‑6, IL‑1β, p‑p38MAPK, NF‑κB and AP‑1 activation, in addition to TLR4 expression, in the lung. PHC effectively attenuated THS‑induced ALI, and inhibited TLR4 expression, reduced the activation of p‑p38MAPK, NF‑κB and AP‑1, and downregulated the expression of pro‑inflammatory mediators. In conclusion, the results of the present study demonstrated that PHC may exert an anti‑inflammatory effect and attenuate THS‑induced ALI by inhibiting the TLR4 signaling pathway. These preclinical findings may offer a novel therapeutic strategy to restrict TLR4 overactivation in ALI.

Intracerebroventricular administration of cigarette smoke condensate induced generalized seizures reduced by muscarinic receptor antagonist in rats

Tobacco smoking is considered the greatest risk factor for early death caused by noncommunicable diseases. Currently, there are more than one billion tobacco smokers in the world predisposed to many diseases including heart attack, stroke, cancer, and premature birth or birth defects related to the consumption of cigarettes. However, studies on the association between tobacco smoking and seizures or epilepsy are insufficient and not well documented. In the present study, the authors examined the convulsive effects of the intracerebroventricular administration of cigarette smoke condensate (CSC, 2μl/Rat) in rats and compared it with the intensity of seizures in the kainic acid (KA)-induced seizure model of epilepsy. The role of the cholinergic system was also investigated by testing the effect of the muscarinic acetylcholine receptors (mAChRs) antagonist atropine (2ml/kg) on CSC-induced seizures. The results indicate that a central injection of CSC produces an epileptic behavior similar to that induced by KA, the similarities include the following parameters: time latency of seizures, latency and duration of tonic-clonic seizures, duration of seizures, survival, and tonic-clonic rate. However, a pretreatment with atropine reduced seizures and all their parameters.

Protective effects of scopolamine and penehyclidine hydrochloride on acute cerebral ischemia-reperfusion injury after cardiopulmonary resuscitation and effects on cytokines

The objective of this study was to investigate the protective effects of scopolamine and penehyclidine hydrochloride on acute cerebral ischemia-reperfusion injury after cardiopulmonary resuscitation, and the effect on cytokine levels. Eighty patients with cardiac arrest admitted to our hospital from June 2011 to December 2015 were recruited and randomly divided into two groups (n=40 each). Following cardiopulmonary resuscitation, scopolamine was administered in the control group, whereas penehyclidine hydrochloride was administered in the observation group. After intervention, the following medical indicators were compared between the groups: Intracranial pressure, cerebral oxygen partial pressure, cerebral perfusion pressure, assessment of the balance of cerebral oxygen supply and demand, levels of neuron-specific enolase (NSE) and blood lactic acid, levels of oxidative stress markers, and levels of inflammatory-related factors. Additionally, the areas of brain tissue edema and National Institutes of Health Stroke Scale (NIHSS) scores before and after intervention were compared. Rescue success rates of the groups were recorded. After intervention, the following indicators were lower in the observation group than in the control group: Intracranial pressure (p<0.05), levels of NSE (p<0.05), levels of blood lactic acid (p<0.05), levels of malondialdehyde (p<0.05), and levels of interleukin 6 (IL-6), tumor necrosis factor-α, IL-1, and hs-CRP (p<0.05). However, the following indicators were higher in the observation group than in the control group: Cerebral oxygen partial pressure, cerebral perfusion pressure (p<0.05), levels of CaO₂, CjvO₂, and CERO₂ (p>0.05), and levels of superoxide dismutase and glutathione peroxidase (p<0.05). Additionally, the areas of brain tissue edema after intervention were smaller in the observation group than those before intervention and those after intervention in the control group (p<0.05). Similarly, the NIHSS scores after intervention in the observation group were lower than those before intervention and those after intervention in the control group (p<0.05). Rescue success rate was significantly higher in observation group than in control group (p<0.05). In conclusion, administration of penehyclidine following cardiopulmonary resuscitation can effectively improve cerebral perfusion pressure, lower intracranial pressure, reduce brain tissue edema and inflammation, and improve neurological function.

Penehyclidine hydrochloride post-conditioning reduces ischemia/reperfusion-induced cardiomyocyte apoptosis in rats

Ischemic heart disease is a major cause of mortality and disability worldwide. Timely reperfusion is currently the most effective method of treating ischemic heart disease; however, abrupt reperfusion may cause ischemia/reperfusion (I/R) injury. Apoptosis serves an important role in the progression of myocardial I/R injury and it has been demonstrated that the mitochondria are the center of regulation for apoptosis. Penehyclidine hydrochloride (PHC) is used during surgery and has recently been identified as a new type of anticholinergic drug. It has been demonstrated in vivo that pretreatment with PHC reduces myocardial apoptosis in rat hearts. The present study aimed to investigate the effects of PHC post-conditioning on myocardial cell apoptosis in a rat model of myocardial I/R and to determine whether the mitochondria-induced pathway was activated. Male Wistar rats were evenly and randomly categorized into 4 experimental groups as follows: i) Sham group; ii) I/R group; iii) PHC+sham group; and iv) PHC+I/R group. A PHC (1 mg/kg) post-conditioning approach (5 min before reperfusion) was used in addition to I/R in the PHC-treated groups. Following 3 h reperfusion, flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed to measure myocardial cell apoptosis. A JC-1 staining method was performed to measure the mitochondrial membrane potential of myocardial cells. The expression of Bax, Bcl-2, voltage dependent anion-selective channel protein 1 (VDAC1), cytosol cytochrome c (cyt-c) and cleaved caspase-3 was analyzed using western blotting. PHC post-conditioning significantly reduced apoptosis in cardiomyocytes, significantly downregulated the expression of Bax, VDAC1, cytosol cytochrome c and cleaved caspase-3 but significantly upregulated the expression of Bcl-2. PHC post-conditioning also restored the mitochondrial membrane potential. Thus, the present study demonstrated that PHC post-conditioning protects cardiomyocytes against apoptosis in the rat model of myocardial I/R by inhibiting the mitochondria-induced intrinsic pathway.

Penehyclidine hydrochloride preconditioning provides cardiac protection in a rat model of myocardial ischemia/reperfusion injury via the mechanism of mitochondrial dynamics mechanism

To investigate that penehyclidine hydrochloride (PHC) plays a cardiac protection role in myocardial ischemia/reperfusion injury (IRI) through mitochondrial dynamics mechanism. Rat model of myocardial I/R injury was established by the ligation of left anterior descending coronary artery for 30min followed by 3h perfusion. Before I/R, the rats were pretreated with or without PHC. Cardiac function was measured by echocardiography. The activities/levels of myocardial enzymes, oxidants and antioxidant enzymes were detected. Evans blue/TTC double staining was performed to assess infarct size. Cell apoptosis was evaluated by TUNEL assay. Western blot and real time fluorescent quantitative PCR was performed to analyze the expression of Drp₁, Mfn₁, Mfn₂. Meanwhile, the rats were given a single injection of PHC before I/R. The effects of PHC on myocardial infarct and cardiac function were investigated after 7 days post-reperfusion. Our results showed that PHC pretreatment improved imbalance of mitochondrial dynamics induced by oxidative stressor in IRI. PHC preconditioning alleviated apoptotic rate of cell by improving the imbalance of mitochondrial dynamics in IRI. Meanwhile, we showed that PHC remarkably improved cardiac function, myocardial injury by decreasing infarct size and attenuated levels of myocardial enzyme. Additionally, PHC also exerted long-term cardiac protection in a rat model of I/R injury by decreasing infarct size and improving cardiac function. These results suggested that PHC could efficiently protect the rats against I/R-induced myocardial injury via the mechanism of mitochondrial dynamics.

Cardioprotective time-window of Penehyclidine hydrochloride postconditioning: A rat study

Pharmacological postconditioning offers a clinical perspective for all patients with ischemic heart disease. Penehyclidine hydrochloride (PHC) is a new type of anticholinergic drug. We previously reported that PHC preconditioning protects against I/R injury in rat hearts in vivo. Ischemic heart disease often occurs suddenly, so postconditioning is more significant than preconditioning. However, studies evaluating myocardial protective effects of PHC postconditioning are unavailable. We explored the effects and time-window of cardioprotection of PHC postconditioning in myocardial I/R injury. PHC was administered by intravenous at various times (t = -5, 0, 5, 10, 15, or 30min) after the onset of reperfusion in addition to I/R rat. We observed five different indicators including infarct size, inflammatory response, myocardial enzyme, oxidative stress, and Ca²⁺ overload to quantify the effect of cardioprotection. Evans blue and TTC staining were used to measure myocardial infarct size. The expression of NF-κ B and IκB-α was analyzed using Western blot. ELISA was conducted to detect inflammatory and anti-inflammatory mediators. The Ca²⁺ level was determined using assay kit. PHC postconditioning (from -5 to 10min after the onset of reperfusion) significantly reduced infarct size, downregulated NF-κ B expression, and decreased the release of inflammatory mediators, while significantly upregulating IκB-α expression and increasing the release of anti-inflammatory mediators. All PHC postconditioning groups significantly reduced Ca²⁺ level. PHC postconditioning is cardioprotective over a larger time-window (from -5 to 10min after the onset of reperfusion). The probable mechanism is inhibition of NF-кB regulated inflammatory response pathway.

Penehyclidine Hydrochloride Pretreatment Ameliorates Rhabdomyolysis-Induced AKI by Activating the Nrf2/HO-1 Pathway and Alleviating [corrected] Endoplasmic Reticulum Stress in Rats. The

Acute kidney injury (AKI) is one of the most severe complications of rhabdomyolysis (RM). The underlying mechanisms and potential preventions need to be investigated. Penehyclidine hydrochloride (PHC) was reported to ameliorate renal ischemia-reperfusion injury, but the effect of PHC on RM-reduced AKI is unknown. In this study, we established a rat model of RM-induced AKI using an intramuscular glycerol injection in the hind limbs. Rats were pretreated with PHC before the glycerol injection, and the heme oxygenase-1 (HO-1) inhibitor ZnPP was introduced to evaluate the effect of HO-1 on RM-induced AKI. PHC pretreatment ameliorated the pathological renal injury and renal dysfunction, and decreased the renal apoptosis rate in RM-induced AKI. PHC significantly up-regulated HO-1 expression, increased HO-1 enzymatic activity and decreased the accumulation of myoglobin in renal tissues. This effect was partly inhibited by ZnPP. PHC pretreatment also effectively up-regulated nuclear factor erythroid 2-related factor 2 (Nrf2) and down-regulated glucose regulated protein 78 (GRP78) and caspase-12 at both the gene and protein levels. These results suggest that the protective effects of PHC pretreatment on RM-induced AKI occur at least in part through activating the Nrf2/HO-1 pathway and alleviating endoplasmic reticulum stress (ERS) in rat renal tissues.

Penehyclidine Hydrochloride Preconditioning Provides Cardioprotection in a Rat Model of Myocardial Ischemia/Reperfusion Injury

To investigate the impacts and related mechanisms of penehyclidine hydrochloride (PHC) on ischemia/reperfusion (I/R)-induced myocardial injury. A rat model of myocardial I/R injury was established by the ligation of left anterior descending coronary artery for 30 min followed by 3 h perfusion. Before I/R, the rats were pretreated with or without PHC. Cardiac function was measured by echocardiography. The activities/levels of myocardial enzymes, oxidants and antioxidant enzymes were detected. Evans blue/TTC double staining was performed to assess infarct size. Cardiomyocyte apoptosis was evaluated by TUNEL assay. The release of inflammatory cytokines and inflammatory mediators was detected by ELISA. Western blot was performed to analyze the expression of COX-2, IκB, p-IκB and NF-κB. Meanwhile, the rats were given a single injection of H-PHC before I/R. The effects of PHC on myocardial infarct and cardiac function were investigated after 7 days post-reperfusion. We found that PHC remarkably improved cardiac function, alleviated myocardial injury by decreasing myocardial enzyme levels and attenuated oxidative stress in a dose-dependent manner. Additionally, PHC preconditioning significantly reduced infarct size and the apoptotic rate of cardiomyocytes. Administration of PHC significantly decreased serum TNF-α, IL-1β, IL-6 and PGE₂ levels and myocardium COX-2 level. Meanwhile, the expression levels of p-IκB and NF-κB were downregulated, while IκB expression was upregulated. H-PHC also exerted long-term cardioprotection in a rat model of I/R injury by decreasing infarct size and improving cardiac function. These results suggest that PHC can efficiently protect the rats against I/R-induced myocardial injury.

Development and validation of an improved HPLC-MS/MS method for comparative pharmacokinetics of penehyclidine hydrochloride following a single intravenous or intramuscular injection

Penehyclidine hydrochloride (PHC) is an anticholinergic drug with both antimuscarinic and antinicotinic activity. In order to compare the pharmacokinetics of two administration routes (intravenous injection (i.v.) and intramuscular injection (i.m.)) of PHC, an improved High Performance Liquid Chromatography Tandem Mass Spectrometry (HPLC-MS/MS) bioanalytical method was developed for the quantification of PHC in plasma and urine using verapamil as the internal standard (I.S.). Chromatography was performed using a Thermo Hypersil GOLD column (30mm×2.1mm, 3μm), with a gradient elution of 1‰ formic acid-10mmol/L ammonium acetate and acetonitrile at 0.3mL/min. Detection and quantitation were performed by electrospray ionization (ESI) and multiple reaction monitoring (MRM) in the positive ion mode. The most intense [M+H](+) MRM transition of PHC at m/z 316.2→128.3 was used for PHC quantitation, and the transition at m/z 454.6→303.2 was used to monitor I.S. The lower limit of quantification (LLOQ) was 0.05 ng/mL. The intraday precision was <6.71% and the interday precision was <11.69%. The pharmacokinetic parameters of i.v. and i.m. administration routes were as follows (i.v. vs i.m.): t1/2 15.73 vs 17.24h, Tmax 0.06 vs 0.26h, AUC0-t 69.35 vs 67.90hng/mL, AUC0-inf 78.24 vs 79.67hng/mL, Cmax 37.5 vs 9.1ng/mL, Ae0-24h 22.7 vs 25.21μg. There were no significant differences between parameters t1/2 and AUC (P>0.05), but significant differences were observed in Cmax, Tmax and Ae0-24h between the two administration routes (P<0.05). The mean absolute bioavailability of the i.m. administration route was 98.4% (95% confidence interval, 93.4-103.6%). Safety results showed that PHC appeared to be well tolerated in both i.v. and i.m. administration routes and pharmacokinetic results showed that PHC was nearly completely absorbed via i.m. administration route.

Neuroprotective effect of penehyclidine hydrochloride on focal cerebral ischemia-reperfusion injury

Penehyclidine hydrochloride can promote microcirculation and reduce vascular permeability. However, the role of penehyclidine hydrochloride in cerebral ischemia-reperfusion injury remains unclear. In this study, in vivo middle cerebral artery occlusion models were established in experimental rats, and penehyclidine hydrochloride pretreatment was given via intravenous injection prior to model establishment. Tetrazolium chloride, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling and immunohistochemical staining showed that, penehyclidine hydrochloride pretreatment markedly attenuated neuronal histopathological changes in the cortex, hippocampus and striatum, reduced infarction size, increased the expression level of Bcl-2, decreased the expression level of caspase-3, and inhibited neuronal apoptosis in rats with cerebral ischemia-reperfusion injury. Xanthine oxidase and thiobarbituric acid chromogenic results showed that penehyclidine hydrochloride upregulated the activity of superoxide dismutase and downregulated the concentration of malondialdehyde in the ischemic cerebral cortex and hippocampus, as well as reduced the concentration of extracellular excitatory amino acids in rats with cerebral ischemia-reperfusion injury. In addition, penehyclidine hydrochloride inhibited the expression level of the NR1 subunit in hippocampal nerve cells in vitro following oxygen-glucose deprivation, as detected by PCR. Experimental findings indicate that penehyclidine hydrochloride attenuates neuronal apoptosis and oxidative stress injury after focal cerebral ischemia-reperfusion, thus exerting a neuroprotective effect.

Effect of penehyclidine hydrochloride on β-arrestin-1 expression in lipopolysaccharide-induced human pulmonary microvascular endothelial cells

β-arrestins are expressed proteins that were first described, and are well-known, as negative regulators of G protein-coupled receptor signaling. Penehyclidine hydrochloride (PHC) is a new anti-cholinergic drug that can inhibit biomembrane lipid peroxidation, and decrease cytokines and oxyradicals. However, to date, no reports on the effects of PHC on β-arrestin-1 in cells have been published. The aim of this study was to investigate the effect of PHC on β-arrestin-1 expression in lipopolysaccharide (LPS)-induced human pulmonary microvascular endothelial cells (HPMEC). Cultured HPMEC were pretreated with PHC, followed by LPS treatment. Muscarinic receptor mRNAs were assayed by real-time quantitative PCR. Cell viability was assayed by the methyl thiazolyl tetrazolium (MTT) conversion test. The dose and time effects of PHC on β-arrestin-1 expression in LPS-induced HPMEC were determined by Western blot analysis. Cell malondialdehyde (MDA) level and superoxide dismutase (SOD) activity were measured. It was found that the M3 receptor was the one most highly expressed, and was activated 5 min after LPS challenge. Furthermore, 2 μg/mL PHC significantly upregulated expression of β-arrestin-1 within 10 to 15 min. Compared with the control group, MDA levels in cells were remarkably increased and SOD activities were significantly decreased in LPS pretreated cells, while PHC markedly decreased MDA levels and increased SOD activities. We conclude that PHC attenuated ROS injury by upregulating β-arrestin-1 expression, thereby implicating a mechanism by which PHC may exert its protective effects against LPS-induced pulmonary microvascular endothelial cell injury.

A novel muscarinic antagonist R2HBJJ inhibits non-small cell lung cancer cell growth and arrests the cell cycle in G0/G1

Lung cancers express the cholinergic autocrine loop, which facilitates the progression of cancer cells. The antagonists of mAChRs have been demonstrated to depress the growth of small cell lung cancers (SCLCs). In this study we intended to investigate the growth inhibitory effect of R2HBJJ, a novel muscarinic antagonist, on non-small cell lung cancer (NSCLC) cells and the possible mechanisms. The competitive binding assay revealed that R2HBJJ had a high affinity to M3 and M1 AChRs. R2HBJJ presented a strong anticholinergic activity on carbachol-induced contraction of guinea-pig trachea. R2HBJJ markedly suppressed the growth of NSCLC cells, such as H1299, H460 and H157. In H1299 cells, both R2HBJJ and its leading compound R2-PHC displayed significant anti-proliferative activity as M3 receptor antagonist darifenacin. Exogenous replenish of ACh could attenuate R2HBJJ-induced growth inhibition. Silencing M3 receptor or ChAT by specific-siRNAs resulted in a growth inhibition of 55.5% and 37.9% on H1299 cells 96 h post transfection, respectively. Further studies revealed that treatment with R2HBJJ arrested the cell cycle in G0/G1 by down-regulation of cyclin D1-CDK4/6-Rb. Therefore, the current study reveals that NSCLC cells express an autocrine and paracrine cholinergic system which stimulates the growth of NSCLC cells. R2HBJJ, as a novel mAChRs antagonist, can block the local cholinergic loop by antagonizing predominantly M3 receptors and inhibit NSCLC cell growth, which suggest that M3 receptor antagonist might be a potential chemotherapeutic regimen for NSCLC.

Penehyclidine hydrochloride: a potential drug for treating COPD by attenuating Toll-like receptors

Background

The aim of this review was to evaluate and summarize the available scientific information on penehyclidine hydrochloride (PHC) for the treatment of chronic obstructive pulmonary disease (COPD) as a result of its ability to attenuate Toll-like receptors. Penehyclidine hydrochloride is an anticholinergic drug manufactured in China, with both antimuscarinic and antinicotinic activity. PHC is used widely in the clinic as a reversal agent in cases of organic phosphorus poisoning and soman poisoning, but also may also have an important role as a bronchodilator in the treatment of obstructive airway disease, including asthma and, in particular, COPD.

Methods

Our bibliographic sources included the CAPLUS, MEDLINE, REGISTRY, CASREACT, CHEMLIST, CHEMCATS, and CNKI databases, updated to September 2012. In order to assess the data in detail, we used the search terms “penehyclidine hydrochloride,” “COPD,” “muscarinic receptor,” and “toll-like receptors.” Papers were restricted to those published in the English and Chinese languages, and to “paper” and “review” as the document type. Patents were also reviewed.

Results

Our survey mainly yielded the results of research on PHC and the mechanisms of COPD. COPD is a preventable and treatable disease with some significant extrapulmonary manifestations that may contribute to its severity in some patients. Recently, it has been shown that muscarinic receptors may interact with Toll-like receptors. Basic and clinical studies of the relationship between the mechanism of action and the effects of PHC in the respiratory tract have been studied by a number of laboratories and institutions. The main advantages of PHC are that it has few M₂ receptor-associated cardiovascular side effects and attenuates Toll-like receptors.

Conclusion

PHC may be a promising candidate agent in the treatment of COPD in the future because of its ability to attenuate Toll-like receptors. This review should be of help to those intending to research this topic further.

The effect of dorsal hippocampal administration of nicotinic and muscarinic cholinergic ligands on pentylenetetrazol-induced generalized seizures in rats

In the present study, the effects of intrahippocampal injections of cholinergic ligands on pentylenetetrazol (PTZ)-induced seizures were investigated in rats. The rats were assigned to 1 of the following 9 groups: saline, nicotine (0.5 or 1 μg), atropine (0.25 or 1 μg), oxotremorine-M (0.1 or 1 μg), or mecamylamine (2 or 8 μg). Cholinergic ligands were administered via intrahippocampal infusion 30 min before seizure induction (intraperitoneal injection of 80 mg/kg PTZ). Results show that antagonists caused nonsignificant increases in the latency of tonic-clonic seizures, significant decreases in the duration of tonic-clonic seizures, significant decreases in the latency of death, and increases in mortality rate. Agonists led to increases in the duration of tonic-clonic seizures, decreases in the latency of death, and decreases in mortality rate. These results provide compelling evidence that cholinergic ligands show modulatory effects on a PTZ model of acute seizure in the rat hippocampus.

Structural elucidation of in vivo metabolites of phencynonate and its analogue thiencynonate in rats by HPLC-ESI-MSn

The structural elucidation of the metabolites of phencynonate and its analogue thiencynonate in rats was performed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS(n)) in positive ion mode, by comparing their changes in molecular masses (DeltaM), retention times and spectral patterns with those of the parent drug. Phencynonate and thiencynonate were easily biotransformed in vivo by the pathways of N-demethylated, oxidative, hydroxylated and methoxylated to form seventeen metabolites that retained the some features of the two parent molecules. These metabolites included ten phencynonate metabolites (N-demethyphencynonate monoxide, N-demethyhydroxy phencynonate, phencynonate monoxide, hydroxyphencynonate, phencynonate dioxide, methoxyphencynonate, dihydroxyphencynonate, dihydroxyphencynonate, hydroxymethoxy phencynonate, trihydroxyphencynonate) and seven thiencynonate metabolites (N-demethy thiencynonate, N-demethythiencynonate monoxide, N-demethyhydroxythiencynonate, thiencynonate monoxide, hydroxythiencynonate, hydroxythiencynonate monoxide, dihydroxy thiencynonate). The described method has wide applicability to rapidly screen and provide structural information of these metabolites. The identifications of precise structures of these metabolites need to be confirmed by other techniques such as the (1)H and (13)C NMR.

Nerve agent exposure elicits site-specific changes in protein phosphorylation in mouse brain

Organophosphorus (OP) compounds cause toxic symptoms, including convulsions, coma, and death, as the result of irreversible inhibition of acetylcholinesterase (AChE). The development of effective treatments to block these effects and attenuate long-term cognitive and motor disabilities that result from OP intoxication is hampered by a limited understanding of the CNS pathways responsible for these actions. We employed a candidate method (called CNSProfile) to identify changes in the phosphorylation state of key neuronal phosphoproteins evoked by the OP compound, diisopropyl fluorophosphate (DFP). Focused microwave fixation was used to preserve the phosphorylation state of phosphoproteins in brains of DFP-treated mice; hippocampus and striatum were analyzed by immunoblotting with a panel of phospho-specific antibodies. DFP exposure elicited comparable effects on phosphorylation of brain phosphoproteins in both C57BL/6 and FVB mice. DFP treatment significantly altered phosphorylation at regulatory residues on glutamate receptors, including Serine897 (S897) of the NR1 NMDA receptor. NR1 phosphorylation was bi-directionally regulated after DFP in striatum versus hippocampus. NR1 phosphorylation was reduced in striatum, but elevated in hippocampus, compared with controls. DARPP-32 phosphorylation in striatum was selectively increased at the Cdk5 kinase substrate, Threonine75 (T75). Phencynonate hydrochloride, a muscarinic cholinergic antagonist, prevented seizure-like behaviors and the observed changes in phosphorylation induced by DFP. The data reveal region-specific effects of nerve agent exposure on intracellular signaling pathways that correlate with seizure-like behavior and which are reversed by the muscarinic receptor blockade. This approach identifies specific targets for nerve agents, including substrates for Cdk5 kinase, which may be the basis for new anti-convulsant therapies.

Characterization of the effect of penehyclidine hydrochloride on muscarinic receptor subtypes mediating the contraction of guinea-pig isolated gastrointestinal smooth muscle

Objectives

The aim was to characterize the effect of penehyclidine hydrochloride, which mediates the relaxation of guinea-pig isolated gastrointestinal smooth muscle, on muscarinic receptor subtypes.

Methods

Radioimmune assay was used to determine cAMP levels in isolated guinea-pig gastrointestinal smooth muscle to compare the selective effects of penehyclidine hydrochloride on muscarinic receptor subtypes.

Key findings

The results indicated that the relaxing effect of penehyclidine hydro-chloride on isolated gastrointestinal smooth muscle contraction induced by acetylcholine was stronger than that of atropine (based on PA2 values). In the radioimmune assay, penehyclidine hydrochloride increased the cAMP content in isolated guinea-pig stomach smooth muscle and decreased the cAMP content in isolated guinea-pig intestinal smooth muscle, but the difference was not statistically significant at a dose of 10 μmol/1.

Conclusions

The results suggest that penehyclidine hydrochloride has little or no effect on M2 receptor subtypes in guinea-pig gastrointestinal smooth muscle.

Underlying mechanism of penehyclidine hydrochloride on isolated rat uterus

We investigated the underlying mechanisms of penehyclidine hydrochloride (PHC), a novel selective anticholinergic drug on isolated rat uterus. The method of radio-immunity assay was further employed to determine cyclic adenosine mono phosphate (cAMP) levels in isolated rat uterus for comparing with selective effect on muscarinic receptor subtypes. In the assay, PHC could decrease the content of cAMP in isolated rat uterus, but the difference was not statistically significant at dose of 10 mumol/L. In conclusion, our results suggested that PHC has no or poor effect on M(2) receptor subtypes in isolated rat uterus.

Protective effects of penehyclidine hydrochloride on septic mice and its mechanism

Anticholinergics can have protective effects against septic shock. Penehyclidine hydrochloride (PHC) is a novel anticholinergic agent exhibiting few cardiovascular side effects. This work explored the protective effects of PHC on septic mice and its mechanism. Mice were randomly divided into four groups: sham control, cecal ligation and puncture (CLP), CLP/0.3 mg/kg PHC, and CLP/0.45 mg/kg PHC, with 10 mice in each. One hour before surgery, PHC-treated mice received an intraperitoneal injection of PHC and an equal volume of saline in the other two groups. Blood plasma and tissue samples were collected at 12 h after surgery. Serum TNF-alpha, histopathology, superoxide dismutase (SOD), malondialdehyde (MDA), and expression of iNOS in lung and hepatic tissues were examined. Another 40 mice were randomly assigned to four equal groups to observe survival status during 96 h after operation. Treatment of 0.45 mg/kg PHC markedly decreased TNF-alpha, MDA content, and iNOS mRNA expression, and enhanced SOD activity (P < 0.05 and P < 0.01). Treatment of 0.45 mg/kg PHC might have a protective effect against sepsis. Its action mechanisms are probably involved in the inhibition of inflammatory factor production and suppression of iNOS mRNA expression and lipidperoxidation.

Protection against soman-induced neuropathology and respiratory failure: A comparison of the efficacy of diazepam and avizafone in guinea pig

The purpose of this study was to compare the efficacy of diazepam and the pro-diazepam avizafone in preventing the severity of soman-induced pathology in guinea pig. Survival, respiration and seizures of experimental animals were investigated with on-line monitoring of respiratory and EEG parameters. Guinea pigs were pretreated with pyridostigmine (0.1mg/kg i.m.) and 30 min later challenged with 1 or 2 LD50 soman. One minute after intoxication they were treated with atropine (3 or 33.8 mg/kg), pralidoxime chloride (32 mg/kg) and either diazepam (2 mg/kg), avizafone (3.5 mg/kg) or saline solution. The highest dose of atropine (33.8 mg/kg) gave a protective effect in groups treated without anticonvulsants by reducing the severity of clinical signs and death within 24 h but also by decreasing seizure occurrence and brain injuries. When injected at the similar molar dose of 7 micromoles/kg, the protection of anticonvulsants against soman neurotoxicity was higher with the atropine/pralidoxime/avizafone combination than with atropine/pralidoxime/diazepam. Indeed, when atropine was used at the lowest dose, avizafone was found to prevent early mortality and seizures occurrence with better efficacy than diazepam. On the other hand, when added to the therapy, the both anticonvulsants did not prevent the moderate EEG depression (reduction of amplitude by 30-52%) observed under 2 LD50 soman. Moreover, the number of animals suffering from respiratory distress (defined as a decrease of minute ventilation of more than 20% from the baseline value) was enhanced when diazepam or avizafone were used in the therapy. This effect was dependent on the atropine dose and the nature of the anticonvulsant. The beneficial effects of the different therapeutics tested were assessed and compared to the previous data obtained with the same therapies against sarin and from the pharmacokinetics properties of the atropine/diazepam mixture.