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Ketamine has been used clinically as an analgesic and anesthetic since 1970. Recently, it has been concerned due to its rapid and effective antidepressant effect. However, the psychiatric adverse reactions caused by ketamine such as addiction and hallucination limit its clinical application, yet the mechanism of the adverse reactions is still unclear. At present, it is generally believed that the pharmacological effects of ketamine are mainly mediated by N-methyl-D-aspartate acid (NMDA) receptors, but increasing numbers of research evidences suggest that the opioid receptor also play an important role in the pharmacological effects of ketamine. This review, based on the relevant literature published publicly in the past 20 years, summarizes the mechanisms of opioid receptors in the pharmacological effects of ketamine, such as anesthesia, analgesia, anti-depressant, anti-addiction and addiction, providing reference for revealing the mechanism of ketamine, and making beneficial exploration for solving the clinical side effects of ketamine.
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The serotonin 2A receptor(5-HT
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Aim To investigate the potential protein post-translational modifications of psychedelic-induced Head-twith response and underling mechanism. Methods Psychedelics LSD, DOM, or Psilocin was administered to rats by intraperitoneal injection to induce head-twitch response, then the most effective dosage was identified to create animal models of head-twitch behavior. Western blot was performed in detecting the protein phosphorylation, acetylation, and ubiquitination in prefrontal cortex of SD rats after 10 min or 30 min injection. Results LSD (0.025 mg • kg~, i. p.), DOM (3 mg•kg
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Classic serotonergic hallucinogens(also known as psychedelics)are powerful psychoactive substances that can induce profound alterations of human consciousness,emotion,and cognition. It is generally believed that the main target of psychedelics for their hallucinogenic effect is 5-hydroxytryptamine 2A receptor(5-HT
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OBJECTIVE The present study was aimed to investigate the role of Wnt/β-catenin sig-naling in spinal VGLUT2 regulation and neuropathic pain. METHODS To elucidate the association be-tween VGLUT2 and neuropathic pain,we determined the expression and distribution characteristics of VGLUT2 in mice subjected to spared nerve injury(SNI),and then observed the effects of two VGLUT2 targeting shRNAs on mechanical allodynia and glutamate release.The effects of Wnt/β-catenin signal-ing on VGLUT2 expression and pain behavior were investigated by using Wnt agonist,Wnt1,and Wnt/β-catenin pathway inhibitor XAV939 in SNI mice.RESULTS SNI surgery induced significant up-regula-tion of VGLUT2 on postoperative days 7,14,and 21.Double immunofluorescence labeling of VGLUT2 with NeuN,MAP2,Iba-1,or GFAP showed that VGLUT2 was mainly expressed in neurons in the dor-sal horn of the spinal cord after SNI(NeuN,MAP2).Intrathecal administration of VGLUT2 shRNAs be-fore or after SNI surgery significantly decreased mechanical allodynia and glutamate release. Mean-while,Wnt1/β-catenin signaling increased significantly after SNI surgery.Over-expression of β-catenin in PC12 cells increased VGLUT2 protein level,intrathecal administration of Wnt agonist or Wnt1 signifi-cantly increased VGLUT2 protein expression in spinal cord, while Wnt/β-catenin pathway inhibitor XAV939 decreased VGLUT2 expression in PC12 cells and spinal cord.Additionally,intrathecal admin-istration of XAV939 7 days after SNI significantly attenuated mechanical allodynia in mice, which was in accordance with down-regulation of VGLUT2 protein levels.VGLUT2 shRNAs significantly attenuat-ed Wnt agonist or Wnt1 induced mechanical allodynia. CONCLUSION Wnt1/β-catenin signaling path-way up-regu-lates the spinal VGLUT2 expression,and this regulation is involved in neuropathic pain behavior.
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OBJECTIVE To explore the mechanism of Gαiand Gβγsubunits on dexmedetomidine (DMED)-induced sedation.METHODS Kunming mice were randomly placed into three groups(DMED group, DMED+dbcAMP/rolipram/gallein/M119 group, dbcAMP/rolipram/gallein/M119 group) to explore the regulation of dbcAMP/rolipram/gallein/M119 on DMED-induced sedation by establishing loss of righting reflex (LORR) model. DbcAMP/rolipram was intracerebroventricular injected and gallein/M119 was intraperitoneal injected 15 min before DMED intravenous injection. In CHO-α2A-AR cells, after administration of DMED/gallein/M119, the regulation on the cAMP accumulation stimulated by Forskolin (FSK) was detected, so was the intracellular calcium ion concentration ([Ca2+]i. The levels of pERK/pCREB were detected by Western Blot to explore the key signal molecules involved in DMED-induced sedation. RESULTS The ED50of DMED-induced LORR (200.0 nmol·kg-1) was increased to 375.0 or 433.3 nmol·kg-1by pre-treatment with cAMP analog dbcAMP(50 nmol/5μl per mouse)or phosphodies-terase 4 inhibitor rolipram(100 nmol/5μl per mouse).In addition,the ED50of DMED-induced LORR was decreased to 113.6 or 136.5 nmol·kg-1when pre-treated with Gβγsubunits inhibitor M119(100 mg·kg-1) or gallein(100 mg·kg-1)respectively.Administration of dbcAMP,rolipram,gallein or M119 alone had little effect on LORR of mice.Gallein(10 μmol·L-1)significantly inhibited forskolin-stimulated cAMP accumu-lation in CHO-α2A-AR cells.Compared with Gβγsubunits inhibitors or DMED alone,[Ca2+]iand pERK1/2 significantly increased after co-administration of Gβγsubunits inhibitors with DMED.DbcAMP(5 μmol·L-1) or rolipram (5 μmol·L- 1) alone had little effect on ERK1/2 phosphorylation, but decreased DMED-induced ERK1/2 phosphorylation after co-administration with DMED. Gβγsubunit inhibitors treatment increased DMED-induced phosphorylation of CREB, whereas dbcAMP or rolipram had little effect on pCREB induced by DMED.CONCLUSION Gβγsubunits might inhibit DMED-induced sedation through cAMP and pERK1/2 pathway,which was opposite to Gαisubuint.
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OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hyp-notics.To explore the mechanism of LCX001 on protection against respiratory depression,a novel AMPA receptor modulator LCX001,synthesized by our Institute of Medicinal Chemistry,is expected to relieve suppressed respiration. METHODS LCX001 was tested to alleviate respiratory depression triggered by opioid(fentanyl and TH-030418),propofol and pentobarbital in the plethysmography recording.The acetic acid writhing and hot-plate tests were conducted to evaluate analgesic effect of LCX001.Binding assay and whole-cell recording were used to analyze the property of LCX001 on positive modulation. The function of AMPA receptors were determined by location of receptors in the membrane and state of channel opening, and both processes were impressed by AMPA receptor regulatory proteins. Ac-cording to the theory,the effect of LCX001 on the expression of stargazin was measured firstly by west-ern blotting. The variation of receptor surface location was observed by live cell imaging. The regula-tion on neuronal Ca2+and cell function was investigated intensively by Ca2+imaging to clarify mecha-nism of LCX001. RESULTS LCX001 effectively rescued and prevented opioid (fentanyl and TH-030418), propofol, and pentobarbital-induced respiratory depression by strengthening respiratory fre-quency and minute ventilation in rats. The acetic acid writhing test and hot-plate test revealed potent anti-nociceptive efficacy of LCX001,in contrast to some ampakines that did not affect analgesia. Fur-thermore,LCX001 potentiated[3H]AMPA and L-glutamate binding affinity to AMPA receptors,and facili-tated glutamate-evoked inward currents in HEK293 cells stably expressing GluA2(R).Importantly,appli-cation of LCX001 generated a significant increase in GluA2(R) surface expression in a mechanism of stargazin up-regulation,and restrained opioid-induced abnormal intracellular Ca2+load,which might par-ticipate in breathing modulation. CONCLUSION The novel pharmacological effect and potential new mechanism of LCX001 might promote ampakines to be a therapeutic option for protection against respi-ratory depression.
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Aim To establish a cell model which stably co-ex-press human kappa opioid receptor (hKOR) and enhanced green fluorescent protein ( EGFP) labeled catalytic domain of cAMP-dependent protein kinase A(PKAcat) fusion protein (PKAcat-EGFP) in Chinese hamster ovary(CHO) cells, laying the foun-dation for the high-throughput screening of hKOR drugs and drug molecular mechanisms in vitro. Methods Hygromycin B resist-ant hKOR recombinant plasmid [ pcDNA3.1/Hygro ( + ) -hKOR] was transfected into CHO cells stably expressing PKA-cat-EGFP by a lipofectin based method. Transfected cells were selected in culture medium containing hygromycin B. The posi-tive clones were selected by PKA redistribution assay. Z’ factor was used for evaluation and validation the reliability of the cell model. PKA redistribution assay and LANCE cAMP 384 Kit were used to test the function of the receptors in selected clone. Results CHO-PKAcat-EGFP/hKOR-13 cell model exhibited stable response in PKA redistribution assay and LANCE cAMP 384 Kit. Treated with 100 nmol·L-1U-50488 for 30 min, the average value of Z’ factor was 0.596, proving the reliability of the cell model. The hKOR expression in cell model remained stable after a few generations. Conclusion The CHO-PKAcat-EGFP/hKOR-13 cell model with stable co-expression of hKOR and PKAcat-EGFP has been successfully established.
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<p><b>OBJECTIVE</b>To investigate the protective effects of tea polyphenols (TP) against myocardial ischemia/reperfusion (IR) injuries and explore the possible mechanisms.</p><p><b>METHODS</b>Langendorff-perfused rat hearts were subjected to ischemia for 30 min followed by reperfusion for another 30 min. Myocardial function indices were measured by a left ventricular cannula via a pressure transducer connected to the polygraph in isolated Langendorff hearts and energy metabolism was measured using (31)P nuclear magnetic resonance (NMR) spectroscopy. Whole-cell atch-clamp technique was used to record calcium inward current (I(Ca-L)) in cultured rat cardiac myocytes.</p><p><b>RESULTS</b>Compared with the control hearts, the ex vivo rat hearts with 2.5 mg/L TP treatment showed significantly increased left ventricular developed pressure (LVDP), maximal rise rate of LVDP (+dp/d(tmax)), maximal fall rate of LVDP (-dp/dt(max)), and coronary flow (CF) (P<0.05). During both cardiac ischemia and reperfusion phase, ATP and PCr levels were elevated significantly in TP-treated hearts compared with those in the control hearts (P<0.05). In cultured rat cardiac myocytes, ICa-L was remarkably decreased by TP at the doses of 2.5 and 5.0 mg/L (P<0.01).</p><p><b>CONCLUSION</b>Our results support a possible protective role of TP against myocardial IR injury by improving myocardial energy metabolism and inhibiting I(Ca-L) in the cardiac myocytes.</p>
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Animals , Rats , Calcium , Metabolism , Calcium Channels , Metabolism , Cells, Cultured , Energy Metabolism , Heart , In Vitro Techniques , Myocardial Reperfusion Injury , Myocardium , Metabolism , Myocytes, Cardiac , Metabolism , Polyphenols , Pharmacology , Tea , ChemistryABSTRACT
Schizophrenia, described as the worst disease affecting mankind, is a severe and disabling mental disorder. Schizophrenia is characterized by complicated symptoms and still lacks a diagnostic neuropathology, so developing schizophrenia animal models which have quantifiable measures tested in a similar fashion in both humans and animals will play a key role in new therapeutic approaches. According to the symptoms of cognitive impairment and emotional disorder, the N-methyl-d-aspartate (NMDA)-receptor antagonist MK-801 was applied to induce schizophrenia-like behavior in mice. Locomotor activity and prepulse inhibition (PPI) were selected as indices and the effect of clozapine was also investigated in this model. The results showed that compared with the normal group, MK-801-treated mice exhibited significantly increased locomotor activity and impaired PPI, and pre-exposure to clozapine could ameliorate the abnormality and make it back to normal level. These findings suggest that the model we established could be a useful tool for antipsychotic drug screening.
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Animals , Male , Mice , Antipsychotic Agents , Pharmacology , Clozapine , Pharmacology , Disease Models, Animal , Dizocilpine Maleate , Inhibition, Psychological , Motor Activity , Receptors, N-Methyl-D-Aspartate , SchizophreniaABSTRACT
Objective:To study the antimalarial mechanism of benflumetol (B). Methods: Flow cytometry (FCM) was used to analyze the effects of B and chloroquine (CQ) on DNA content of Plasmodium berghei and pH value of the lysosome of malarial parasites. Results: DNA content of the plasmodia not treated with any drugs was not changed in 24 hours,while benflumetol could decrease the DNA content: the DNA content began to decrease 2 h after the drug administration and reached the minimum by 16 h, but somewhat increased at 24 h after administration. The pH in the lysosome increased 1 h and restored premedication level 4 h after benflumetol administration. Chloroquine had the same effects on DNA and lysosome pH of malarial parasites.Conclusions: The antimalarial mechanism of benflumetol is directly related to its effect to inhibit the synthesis of DNA.