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Biomedical subjects

Fang Wang

Publications and source records attributed to Fang Wang.

At least 253 records · Page 14Linked to original sources
PubMed2003

[Protective effects of 1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino) propane hydrochloride(DDPH) on brain ischemia injury in rats].

AIM: To study the effects of 1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino) propane hydrochloride(DDPH) on brain ischemia injury in rats. METHODS: By using the middle cerebral artery occlusion (MCAO) induced by nylon surgical thread inserted through the internal carotid artery into the anterior cerebral artery in rats, the effects of DDPH on neuron defects(ND) and infarct size(IS) were investigated. Using incomplete cerebral ischemia in rats, the effects of DDPH on superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in brain tissue and pathological changes in rats were studied. RESULTS: DDPH at the dose of 10 mg.kg-1 i.p. 30 min before ischemia decreased the ND 3 h after ischemia. The IS declined 24 h after ischemia as well. Meanwhile, DDPH was found to increase SOD activity and reduce the MDA content, as well as mitigate pathological damage, of neuron after brain ischemia in rats. CONCLUSION: DDPH showed protective effects on brain ischemia, probably related to its properties of calcium antagonistic effect and increasing the activity of superoxide dismutases.

Animals↗
PubMed2003

[SARS-associated coronavirus gene fragments were detected from a suspected pediatric SARS patient].

UNLABELLED: A Special "Fever and Cough" Clinic was set up at the Children's Hospital Affiliated to Capital Institute of Pediatrics for children with symptoms of fever and cough in late April when the severe acute respiratory syndrome (SARS) epidemic was at its peak in Beijing to separate the children with fever from others during their visit to the Outpatient Department. OBJECTIVE: For patients with fever, normal or low count of white blood cell and with suspected pneumonia suggested by X-ray, it was urgent to determine the etiological agents of the diseases before they were admitted to the hospital. METHODS: Throat swabs or nasopharyngeal aspirate specimens were collected from those patients and common respiratory virus antigens including influenza virus A and B, respiratory syncytial virus, adenovirus, parainfluenza virus types I, II, and III were tested by indirect immunofluorescent assay. The patients with atypical pneumonia diagnosed by X-ray and evidences of common respiratory virus infection were admitted to the regular ward for children with respiratory diseases. Children with pneumonia demonstrated by X-ray and negative for common respiratory viruses were admitted to the isolated ward for suspected SARS patients for the first step and further viral etiological studies were requested. RT-PCR was performed for those patients to detect gene fragments of human metapneumovirus (HMPV), rhinovirus (RhV) and enterovirus (EV) in their specimens. Nested RT-PCR was also developed to detect SARS coronavirus gene fragment from the specimens. Primer sequences for SARS virus detection with the PCR were selected according to the primer sequences published online by WHO on April 18, 2003. All the primers derived from the sequence at the 1b frame of coronavirus replicase gene and products with a size of 368 or 348 bp were expected with 2 different primer pairs. RESULTS: Amplicons with the sizes of 368 bp and 348 bp were obtained from a throat swab specimen collected from a 17 years old girl, who was admitted to the isolated ward because of high fever (39.5 degrees C) for 7 days, cough for 2 days, low WBC count, and pneumonia shown by X-ray when she visited the "Fever and Cough" Clinic, and without known history of contact with probable SARS patient. Antigens for the common respiratory viruses were all negative, RT-PCR for HMPV, RhV and EV were also negative while RT-PCR with different primer pairs for SARS virus were all positive which indicated that SARS coronavirus gene fragments were amplified from the specimen from this girl. The amplified fragment with a size of 368 bp was sequenced and the sequence was compared with those in the GenBank. The sequence shared 100% homology with the sequences from 1b frame of replicase genes from all 17 of SARS coronaviruses published in the GenBank so far, and shared very low homology with 2 reference strains of human coronavirus as well as other animal coronaviruses. The serum collected before her discharge from the hospital (19 days after the onset of the disease) showed SARS specific IgM and IgG antibodies. CONCLUSION: These data indicate that the patient was a confirmed case of SARS. It is of great importance to differentiate SARS patients from those infected with common respiratory viruses during SARS epidemic, especially for pediatric patients, because most of the patients visiting the outpatient department present with the symptoms of fever, cough and normal WBC count. The data mentioned above indicate that antigen and gene detections for those common respiratory viruses are useful methods for the differentiation to avoid the spread of SARS.

Adolescent↗
PubMed2003

[Human metapneumovirus may associate with acute respiratory infections in hospitalized pediatric patients in Beijing, China].

OBJECTIVE: A new respiratory virus, human metapneumovirus (HMPV) was recently identified by scientists in the Netherlands first and then in a few other countries. To investigate if this newly discovered virus is associated with the acute respiratory infections in pediatric patients in Beijing, tests were developed to detect HPMV gene fragments from nasopharyngeal aspirates collected from infants and young children hospitalized for acute respiratory infections from November 2002 to March 2003. METHODS: The HMPV was screened by reverse transcription-polymerase chain reaction (RT-PCR). RNAs were extracted by Trizol from 247 specimens which had been determined as negative for conventional respiratory viruses including RSV, influenza A and B, parainfluenza I, II, III and adenovirus by indirect immunofluorescence test as well as virus isolation. The HMPV RNAs were detected by reverse transcription tests using random primer and M-MLV reverse transcriptase followed by PCR using the primers designed from the published sequence of the N protein-encoding gene from the first HMPV identified in the Netherlands. PCR products were visualized by 1.2% agarose gel electrophoresis. Selected positive PCR products were sequenced and the sequences of the nucleotides and deduced amino acids were compared with those in the GenBank. RESULTS: Among those 247 specimens negative for common respiratory viruses, 74 (30.0%) showed the predicted 213 bp PCR products in agarose gel. Most of clinical diagnoses for these 58 patients were pneumonia (36, 48.6%), bronchiolitis (21, 28.4%), and bronchitis and asthma in some patients. Nearly 90 percent of positive specimens were from patients under 2 years of age. Ten out of 74 amplicons were randomly selected for sequence analysis. When compared with the sequences in the GenBank, the nucleotide sequences of these 10 amplicons shared high homology only with those of HMPVs. The nucleotide sequence identities of these 10 samples with those from the Netherlands and Canada were 87% - 99%. When compared with the nucleotide sequence from the first reported strain by Van den Hoogen (strain HMPV 00-1), the sequence identities of these 10 fragments ranged from 88.7% to 99.1%. Among the 10 amplicons from the specimens, the nucleotide identities were 87.3% - 100%. One of the 10 amplicons (No. 1816) shared lower identity with others (87.3% - 89.7%), whereas the other 9 shared higher identities (95.8% - 100%) with each other. The comparison of amino acids showed that these 10 amplicons showed high homology (95.8% - 100%). Again, amplicon No.1816 shared lower homology (95.8% - 97.2%) with others, whereas the other 9 shared higher homology (98.6% - 100%). The amino acid homology between No.1816 and HMPV 00-1 was 95.8%, whereas that of the other 9 with HMPV 00-1 was 98.6% - 100%. CONCLUSION: These data suggested that some of acute respiratory infections in pediatric patients in Beijing area are related to the newly identified human metapneumovirus. The HMPV circulating in Beijing may have different genotypes.

Acute Disease↗
PubMed2003

[Effect of ouabain on the aortic rings of guinea pig and its interactions with Ca2+, norepinephrine].

AIM: To observe the effects of ouabain on vascular smooth muscle (VSM) of the guinea pig and its interactions with Ca2+ and norepinephrine (NE). METHODS: Using isolated thoracic aortic ring of the guinea pig, the degrees of contractile activity of drugs were recorded. RESULTS: Ouabain showed a direct contractile effect in a concentration-dependent manner on thoracic aortic ring of guinea pig. Ouabain shifted the NE dose-response curve to the left without changing in the maxium response. Ouabain shifted the CaCl2 dose-response curve to the left and upward, increased the maximum response to Ca2+; In Ca(2+)-free medium, the ouabain induced contraction was abolished, an increase in extracellular Ca2+ restored the response; nifedipine and verapamil abolished the ouabain induced contraction. CONCLUSION: The ouabain induced contraction is mainly dependent on the extracellular Ca2+ concentration, independent on the presence of endothelia of aorta, suggesting that Ca2+ antagonist may treat the hypertension induced by ouabain. Ouabain, NE and CaCl2 have synergetic contractile effects, suggesting that the synergetic contractile effects of ouabain and NE may contribute to the generation and development of hypertension.

Animals↗
PubMed2003

[Experimental studies on the apoptosis of HL-60 cells induced by Brucea javanica oil emulsion].

OBJECTIVE: To investigate the inducing effect of Brucea javanica on the apoptpsis of HL-60 cells. METHOD: HL-60 cells were treated with Brucea javanica 1:100, 1:40, 1:20 (v/v) respectively for 6 h and DNA agarose gel electrophoresis, flow cytometry, fluorescence microscope, electron microscope were used to observe the apoptosis inducing effect of Brucea javanica. RESULT: DNA ladder was seen in the 1:40 group. The apoptosis cell percentages of 1:40 and 1:20 group were 86.8% and 97% respectively. Cells of 1:40 group showed obvious apoptosis character under fluorescence microscope. Cells were induced apoptosis in 1:20 and 1:40 Brucea javanica under electron microscope. CONCLUSION: 1:20 and 1:40 Brucea Javanica showed obvious apoptosis inducing effect of HL-60.

Antineoplastic Agents, Phytogenic↗
PubMed2003

[In-vivo dynamic changes of antigen presenting cells infected with recombinant attenuated Salmonella typhimurium expressing green fluorescent protein].

AIM: To clarify in-vivo early dynamic changes of antigen-presenting cells (APCs) infected with recombinant attenuated Salmonella typhimurium. METHODS: BALB/c mice were orally infected with recombinant attenuated Salmonella typhimurium expressing green fluorescent protein (GFP) X4550 (pYAGFP). Peritoneal macrophages were taken out 3 days after infection, cultured for 24 hours, and observed under the fluorescent microscope. Moreover, BALB/c mice were also infected intravenously with X4550 (pYAGFP) and low density cells (LDCs) were isolated and prepared from mouse spleen and liver 3,6 and 12 hours after infection. Infection rates of macrophages and dendritic cells (DCs) were analyzed by flow cytometry. RESULTS: About 50% peritoneal macrophages were X4550 (pYAGFP) positive. Infection rates of macrophages in spleen and liver were about 20%-40%. As for the DCs, the infection rates in spleen and liver were about 4%-10% and 10%-20%, respectively. CONCLUSION: Recombinant attenuated Salmonella can be captured by APCs in-vivo in early infection, which provides a precondition for inducing effective immune responses.

Animals↗
PubMed2003

[Cloning and characterization of cDNAs of cardiotoxin-like protein in Bungarus multicinctus venom gland].

The venom of elapid snakes contains a number of small proteins that display a broad spectrum of pharmacological activities. In study on the neurotoxin from the venom gland of Bungarus multicinctus, five cDNA sequences (MNCTL1-a,MNCTL1-b,MNCTL1-c,MNCTL1-d and MNCTL2) encoding two novel proteins were obtained from the total RNA by reverse transcription-polymerase chain reaction. Among them, four sequences (MNCTL1-b,MNCTL1-c,MNCTL1-d and MNCTL2) are at the length of 505 bp, composing of a 32 bp 5'-untranslational region,a 212 bp 3'-untranslational region, and a 261 bp open reading frame which encodes a 20 amino acids of signal peptide and a 65 amino acids of mature peptide. But the sequence of MNCTL1-a has only 481 bp because of a 24 bp deletion in 3'-untranslational region. Comparison between cDNA sequences obtained here and that of cardiotoxin-like protein reported by Chang previously shows a homological value above 95.8%. Computer simulation based on deduced amino acid sequences reveals that both proteins encoded by these cDNAs and cardiotoxin-like protein share similar molecular characters, suggesting their functional similarity. This result implies that multicopy genes existing in the genome of Bungarus multicinctus encode cardiotoxin-like proteins.

English Abstract↗
PubMed2003

[Studies of enzymatic synthesis of biodiesel].

Biodiesel, an alternative diesel fuel, fatty acid alkyl ester, is made from renewable biological sources such as vegetable oils and animal fats. Two processes for biodiesel synthesis, enzymatic lipase catalytic esterification from fatty acid and transesterification from oils and fats, was investigated. The effects of various lipases, enzyme amount and purity, solvent, water absorbent, inhibition of short chains alcohol, specificity of substrate, molar ratio of substrate on esterification were studied in detail. The esterification degree with the optimal parameter and process can reach up to 92%. The purity of biodiesel obtained by separation and purification is up to 98%, and the half-life of the immobilized lipase for the esterification process can be up to 360hr, Moreover, the preliminary studies of the transesterification including the amount of methanol and mode of adding methanol into reaction system were made. The transesterification degree with adding methanol stepwise can reach 83%.

Biofuels↗
PubMed2002

Purification, characterization and preliminary crystallographic studies of a PR-10 protein from Pachyrrhizus erosus seeds.

A 16 kDa protein SPE16 was purified from the seeds of Pachyrrhizus erosus. Its N-terminal amino-acid sequence showed significant sequence homology to pathogenesis-related proteins from the PR-10 family. An activity assay indicated that SPE16 possesses ribonuclease activity as do some other PR-10 proteins. SPE16 crystals were obtained by the hanging-drop vapour-diffusion method. The space group is P2(1)2(1)2(1), with unit-cell parameters a = 53.36, b = 63.70, c = 72.96 A.

Amino Acid Sequence↗
PubMed2002

Phenotypic and genotypic features of Alport syndrome in Chinese children.

Chinese Alport syndrome (AS) was analyzed in 44 unrelated patients who were screened for mutations in the COL4A5 gene by polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis or PCR direct sequencing in 30 of the 44 patients. The clinical data showed that all patients had hematuria; 25 of 29 male patients (86%) and 9 of 15 female patients (60%) had proteinuria; 11 of 29 male patients (38%) and 1 of 15 female patients (7%) had nephrotic-level proteinuria; 10 of 21 male patients examined (48%) and 1 of 12 female patients examined (8%) had hearing abnormalities. Renal function remained normal despite hearing abnormalities, and ocular lesions occurred in 10%. Among 30 of 44 patients who had a family history of end-stage renal disease (ESRD), 80% (24/30) belonged to X-linked juvenile kindreds, and 20% (6/30) patients to adult kindreds. Of the 44 patients, 14 did not have a family history of ESRD, while 11 of 14 patients diagnosed with X-linked AS did. DNA analysis revealed four missense mutations, two silent mutations, one substitution, and one in-frame deletion. PCR along with Southern hybridization analysis revealed a large deletion of the paired COL4A5 and COL4A6 genes. Chinese AS patients were characterized clinically with hematuria, heavy proteinuria, and more juvenile forms. Mutations in these patients were usually small mutations, while a large deletion involving the 5' part of both COL4A5 and COL4A6 genes was identified.

Adolescent↗
PubMed2002

Probing the molecular basis for potent and selective protein-tyrosine phosphatase 1B inhibition.

Protein-tyrosine phosphatases (PTPs) are important for the control of proper cellular tyrosine phosphorylation. Despite the large number of PTPs encoded in the human genome and the emerging roles played by PTPs in human diseases, a detailed understanding of the role played by PTPs in normal physiology and in pathogenic conditions has been hampered by the absence of PTP-specific inhibitors. Such inhibitors could serve as useful tools for determining the physiological functions of PTPs and may constitute valuable therapeutics in the treatment of several human diseases. However, because of the highly conserved nature of the active site, it has been difficult to develop selective PTP inhibitors. By taking an approach to tether together two small ligands that can interact simultaneously with the active site and a unique proximal noncatalytic site, we have recently acquired Compound 2 (see Fig. 1), the most potent and selective PTP1B inhibitor identified to date, which exhibits several orders of magnitude selectivity in favor of PTP1B against a panel of PTPs. We describe an evaluation of the interaction between 2 and its analogs with PTP1B and its site-directed mutants selected based on hydrogen/deuterium exchange of PTP1B backbone amides in the presence and absence of 2. We have established the binding mode of Compound 2 and identified 12 PTP1B residues that are important for the potency and selectivity of Compound 2. Although many of the residues important for Compound 2 binding are not unique to PTP1B, the combinations of all contact residues differ between PTP isozymes, which suggest that the binding surface defined by these residues in individual PTPs determines inhibitor selectivity. Our results provide structural information toward understanding of the molecular basis for potent and selective PTP1B inhibition and further establish the feasibility of acquiring potent, yet highly selective, PTP inhibitory agents.

Amino Acid Sequence↗
PubMed2002

Unusual effect of column temperature on chromatographic enantioseparation of dihydropyrimidinone acid and methyl ester on amylose chiral stationary phase.

This paper reports an unusual effect of column temperature on the separation of the enantiomers of dihydropyrimidinone (DHP) acid and its methyl ester on a derivatized amylose stationary phase by normal-phase liquid chromatography. The separation of the DHP acid enantiomers was investigated using both carbamate-derivatized amylose and cellulose stationary phases (Chiralpak AD and Chiralcel OD) with an ethanol-n-hexane (EtOH-n-Hex) mobile phase. On the amylose phase, the van 't Hoff plot of the retention factor of the S-(+)-DHP acid was observed to be non-linear while that of R-(-)-DHP acid was linear. Likewise, the van 't Hoff plot for DHP acid enantioselectivity was non-linear with a transition occurring at approximately 30 degrees C. Furthermore, the van 't Hoff plot for the DHP acid enantioselectivity factor for data taken when heating the column from 5 to 50 degrees C was not superimposable with the same plot prepared with data from the cooling process from 50 to 5 degrees C. This observation suggested that the stationary phase was undergoing a thermally induced irreversible conformational change that altered the separation mechanism between the heating and cooling cycles. Similar phenomena were observed for the separation of the enantiomers of the DHP ester probe compound. The conformational change of the AD phase was shown to depend on the polar component of the mobile phase. When 2-propanol (2-PrOH) was used as the modifier instead of EtOH, the van 't Hoff plots for DHP acid were linear and thermally reversible, suggesting that no such irreversible conformational change occurs with this modifier. Conversely, when the AD phase was pre-conditioned with a more polar methanol (MeOH) or water containing mobile phase, thermal irreversibility of DHP acid enantioselectivity was once again observed. Interestingly, when the stationary phase was changed to its cellulose analogue, the Chiralcel OD, all van 't Hoff plots for the retention and selectivity of DHP acid were thermally reversible for both EtOH-n-Hex and 2-PrOH-n-Hex mobile phases.

Chromatography, Liquid↗
PubMed2002

Organic analysis by ion chromatography. 1. Determination of aromatic amines and aromatic diisocyanates by cation-exchange chromatography with amperometric detection.

A method has been developed for the simultaneous determination of a range of aromatic amines using cation-exchange chromatography performed on a standard ion chromatography column using d.c. amperometric detection. The analytes separated were 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA), aniline, o-toluidine, benzidine, p-chloroaniline, 4,4'-diaminodiphenyl (4,4'-DDP), m-nitroaniline and 1-naphthylamine. A Dionex CS12 column was used with gradient elution from an initial eluent of 5% CH3CN+35 mM H2SO4 to 27% CH3CN+35 mM H2SO4 (at 35 min). Detection limits in the range 2.6-22.6 microg/l were observed for all analytes except m-nitroaniline, for which the detection limit was 201 microg/l. Linear calibrations and good precision were observed and the method was applied to the determination of benzidine, p-chloroaniline and 1-naphthylamine in wastewater samples. Further, the separation was also used (after some modification of the eluent conditions) for the determination of 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6-TDI) and 4,4'-methylenediphenyl diisocyanate (4,4'-MDI) after their hydrolysis to 2,4-TDA, 2,6-TDA and 4,4'-DDP. Detection limits for 2,6- and 2,4-TDI and 4,4'-MDI were 3.8, 8.2, and 11.2 microg/l, respectively. The method was applied to the determination of diisocyanates in air.

Amines↗
PubMed2002

Ana o 1, a cashew (Anacardium occidental) allergen of the vicilin seed storage protein family.

BACKGROUND: The allergens responsible for cashew food allergy have not been well characterized. OBJECTIVES: We initiated a study to clone cDNAs encoding cashew food allergens. METHODS: A cashew cDNA library was screened with human serum for IgE-reactive clones and rabbit IgG anti-cashew extract antisera. Reactive clones were sequenced and expressed, and linear epitopes were identified by means of solid-phase overlapping peptide analysis. Immunoblot inhibition was used to identify the native peptide in cashew extract. RESULTS: Four closely related clones reactive with both human and rabbit antisera were sequenced. Sequence analysis showed that these encode members of the vicilin/sucrose-binding protein family of plant seed storage proteins. Screening of the recombinant protein with sera from 20 patients with cashew allergy and 8 cashew-tolerant patients with allergies to other tree nuts showed that 50% and 25% of sera from patients with cashew allergy and cashew-tolerant subjects, respectively, bound the recombinant protein. The corresponding native allergen protein, designated Ana o 1, was located at approximately 50 kd. Epitope mapping revealed 11 linear IgE-binding epitopes, of which 3 appear to be immunodominant. None of the epitopes were shared in common with those of the peanut vicilin allergen Ara h 1. CONCLUSION: Ana o 1, a vicilin-like protein, is a major food allergen in cashews. Cashew and peanut vicilins do not share linear epitopes.

Allergens↗
PubMed2002

Functional evidence for retinoid X receptor (RXR) as a nonsilent partner in the thyroid hormone receptor/RXR heterodimer.

Many members of the thyroid hormone/retinoid receptor subfamily (type II nuclear receptors) function as heterodimers with the retinoid X receptor (RXR). In heterodimers which are referred to as permissive, such as peroxisome proliferator activated receptor/RXR, both partners can bind cognate ligands and elicit ligand-dependent transactivation. In contrast, the thyroid hormone receptor (TR)/RXR heterodimer is believed to be nonpermissive, where RXR is thought to be incapable of ligand binding and is often referred to as a silent partner. In this report, we used a sensitive derepression assay system that we developed previously to reexamine the TR/RXR interrelationship. We provide functional evidence suggesting that in a TR/RXR heterodimer, the RXR component can bind its ligand in vivo. Ligand binding by RXR does not appear to directly activate the TR/RXR heterodimer; instead, it leads to a (at least transient or dynamic) dissociation of a cellular inhibitor(s)/corepressor(s) from its TR partner and thus may serve to modulate unliganded TR-mediated repression and/or liganded TR-mediated activation. Our results argue against the current silent-partner model for RXR in the TR/RXR heterodimer and reveal an unexpected aspect of cross regulation between TR and RXR.

Alitretinoin↗
PubMed2002

[Anti-mutagenicity activity of dehydroepiandrosterone].

OBJECTIVE: The chemopreventive activity and mechanism of dehydroepiandrosterone (DHEA) were studied. METHODS: Model of 7, 12-dimethylbenz (alpha) anthracene (DMBA) induced breast carcinoma in Sprague-Dawley rats, uitra-violet (UV)-induced DNA damage and Salmonella mutation assay were used. RESULTS: In DMBA-induced rat mammary tumor model, the rats were orally given daily DHEA for 2 weeks before DMBA and continued for 10 weeks after DMBA administration. The results showed significant inhibition of tumor development by DHEA. The incidence of mammary carcinoma also decreased significantly on daily dose of oral 25 mg/kg DHEA with the mean tumor volume per rat also remarkably reduced by 92%. Moreover, 25 mg/kg DHEA treatment could significantly increase the carcinoma latency for about 3.5 weeks as compared with the control. Using polymerase chain reaction (PCR) assay, in vitro 10(-9) mol/L DHEA showed significant inhibitory effect on UV-induced DNA damage by 90%. In Ames test, DHEA was found to decrease DMBA and benzo (alpha) pyrene-induced TA98 and TA100 His(+) revertants markedly and the number of Salmonella clones were significantly reduced by 53.2% and 73.0% on dose of 5 microgram DHEA/plate. It was also shown that in vitro 10(-7) mol/L DHEA could also effectively inhibit the G-6-PDH activity, which might play an important role in its chemoprophylaxis activities. CONCLUSION: The results strongly prove that DHEA is a potent cancer chemoprophylaxis agent, which exhibits inhibitory potential on mutation and chemical carcinogen in vivo and in vitro.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2002

Hypnotic activity of melatonin: involvement of semicarbazide hydrochloride, blocker of synthetic enzyme for GABA.

AIM: To assess the effect of semicarbazide hydrochloride (SCZ), the blocker of synthetic enzyme for GABA, on the hypnotic activity of melatonin. METHODS: Righting reflex method in mice and electroencephalography (EEG) in rats were used to determine effects of SCZ on sleep and hypnotic activity of melatonin. RESULTS: Melatonin displayed a marked hypnotic activity both in righting reflex experiment and EEG recording. SCZ had no influence on sleep parameters in mice and rats when it was used alone. However, it blocked the sleep-potentiation effect of melatonin in mice. SCZ also inhibited melatonin-induced increase in total sleep time, slow wave sleep time, and paradoxical sleep time, and prevented melatonin-induced decrease in awake time in rats. CONCLUSION: SCZ antagonized the hypnotic activity of melatonin. It is thought that the hypnotic activity of melatonin is mediated by GABAergic system.

Animals↗