The kynurenine metabolic pathway involves in a cascade of enzyme reaction generated multiple biologically-active compounds.These metabolites are called"kynurenines" which participate in diverse pathophysiological processes,particularly in the central nervous system.The kynurenines have important physiological functions.For example.quinolinic acid is an Nmethyl-D-aspartate(NMDA)receptor agonist.and it can be largely accumulated in the central nervous system in many infectious nervous system diseases,resulting in neuronal excitotoxicity and death.Kynurenic acid antagonizes excitatory glutamate receptors to reduce excitotoxicityinduced neuronal death.This article reviews the related researches of the effects of kynurenine metabolic pathway on the central nervous system.

ObjectiveTo investigate the protein expression of ERK1/2,p-ERK1/2,HIF-1α and α-enolase in hypertrophic cardiomyocytes induced by ET-1 and explore the regulation mechanism of overexpression of α-enolase in hypertrophic cardiomyocytes.MethodsET-1-induced abnormal cardiomyocytes were used as model of cardiac hypertrophy.Cellsurface area, [<'3>H]-leucine incorporation and the actin staining were measured to determine the extent of hypertrophy. Cultured cardiomyocytes were divided into 4 groups at random, control group, PD98059 treated group, ET-1 treated group and PD980594- ET-1 treated group. The protein expressions of ERK1/2, p-ERK1/2,HIF-1α and α-enolase were detected by immunoblotting analysis.ResultsCompared with the control group , cell surface area and [<'3>H] leucine incorporation were increased in ET-1 treated group ((1350.7±107.5)μtm<'2> vs. (896.1±70. 2)μtm<'2> , P<0.05; (1387.9±14.8) dpm vs. (787.7±10.2)dpm,P<0.013. Actin staining showed that ET-1-treated cardiomyoeytes had more intense actin staining and clear cross-striations than did control group, which suggested that myocardial cell hypertrophy could be induced by ET-1 in WKY neonatal cardiomyocytes. After MEK 1/2 inhibitor PD98059 was used, the cell surface area and [<'3>H] leucine incorporation were decreased in PD980594-ET-1 treated group compared with ET-1 treated group[(907.0±92.5)μm<'2> vs. (1350.7±107.5)μm<'2>;(841.5±10. 5)dpm vs. (1387.9±14.8)dpm, both P<0.05], which suggested that myocardial cell hypertrophy could be regulated by ERK1/2 signal pathway. Immunoblotting analysis showed that the protein expressions of p-ERK1/2, HIF-1α and α-enolase increased after ET-1 treatment,while PD98059 as an inhibitor of the upstream kinase of ERK1/2 was used, the protein expressions of HIF-1α and α-enolase were partially inhibited.ConclusionsET-1 induces hypertrophic cardiomyocytes through ERK1/2 phosphorylation in cultured neonatal rat cardiac myocytes.ERK1/2 and HIF-1α signal pathway may play an important role in the overexpression of α-enolase in the hypertrophic cardiomyocytes.

Objective To evaluate the relationship between hepatocyte growth factor (HGF) and myocardial fibrosis in the process of hypertension, and the therapeutic effect of losartan, an angiotension Ⅱ (Ang Ⅱ ) receptor antagonist. Methods Spontaneously hypertensive rats (SHR)were used as experimental model of myocardial fibrosis, and Wistar-Kyoto (WKY) rats were selected as control group. The therapeutic group was given losartan. Cardiac collagen was detected by Masson staining and HGF was determined by immunohistochemistry. All the pictures were analysed by Leica Qwin image disposal and analysis system. Results The cardiac collagen volume fraction (CVF) in SHR increased with aging and had a negative correlation with myocardium HGF. Losartan therapy increased the myocardium HGF expression but decreased the CVF. Conclusions Myocardium HGF may play a robe in hypertensive myocardial fibrosis due to its anti-fibotic effect reducing. Ang 1I AT1 receptor antagonist attenuates cardiac fibrosis by increasing myocardium HGF expression.

Aim To investigate the effects of angiotensin Ⅱ(AngⅡ),AT1 receptor antagonist losartan and AT2 receptor antagonist PD123177 on protein synthesis rate and AT1 receptor mRNA expression in cultured neonatal rat cardi ac myocytes. 　Methods The protein synthesis rate in cultured cardiac myocytes w as determined by the3H-leucine incorporation,AT1 receptor mRNA expressi on of cardiac myocytes was assessed by reverse transcription-polymerase chain reaction(RT-PCR). 　Results AngⅡ increased the 　3H-leucine incorporation in cultured cardiac myocytes in a dose dependent manner,losartan but not PD12317 7 could significantly inhibit AngⅡ induced protein synthesis,;AT1 receptor mRNA expression was upregulated after AngⅡ,and inhibited by losartan,but not PD123177. 　Conclusion AngⅡ can induce cardiac myocytes hypertrophy via upregulating AT1 receptor,and AT1 receptor antagonist can decrease AT1 rec eptor expression,reduce cardiac myocytes hypertrophy.

Objective To screen the mutation in P and 7 subunit of epithelial sodium channel (ENaC) gene in the relatives of a patient diagnosed as Liddle's syndrome. Methods In a family of three generations, seven family members were affected with hypertension, among them a girl aged 14 years was diagnosed as Laddie's syndrome and her mother and maternal grandsire died of stroke at thirty-eight years. Peripheral blood samples were collected from all living members of the family and total genomic DNA was prepared for genetic analysis. Polymerase chain reaction (PCR) was used for amplifying the final exon of the ? ENaC (codon 513-638) and ? ENaC (codon 524-631 )gene. PCR products were purified and subjected to direct DNA sequencing. Results Genetic analysis of the ? ENaC gene revealed a missense mutation of CCC (Pro) to TCC (Ser)at codon 616 in the index case and two other family members. In these three family members, a new variant of GAC (Asp) to CAC(His) at codon 632 was found, which was linked with 616 (Ser) . This variant was not detected by direct sequencing the final exon of ? ENaC gene in 150 unrelated subjects. Through clinical examinations and biochemical measurement, thSese two mutation carriers' biochemical characteristics were all concordant with Liddle's syndrome. Neither mutation could be detected in other members of this family. The mutation TGG(Trp)573TAG(Term) of ? ENaC gene could not be found in this family either. Conclusions (1) Screening for specific mutations of ENaC in relatives of patients affected with Liddle's syndrome can be used to identify previously unrecognized cases within families. (2) A new missense mutation in the ? ENaC gene is found in this family.

Objective:To explore the alteration of brain‐derived neurotrophic factor (BDNF) signaling and the influ‐ence of irbesartan on it in hippocampus of angiotensin‐converting enzyme 2 (ACE2) knock‐out (KO) mice . Meth‐ods:The 10~11‐week ACE2 KO (Ace2/y ) mice received daily treatment with angiotensin II (Ang II) type 1 (AT1) receptor blocker irbesartan (50 mg/kg) or placebo for two weeks. The wild‐type mice (WT ,Ace2+ /y ) were regarded as normal control. Western blotting method was used to measure levels of BDNF and extracellular signal regulated kinase 1/2 (ERK1/2) in the mice hippocampus. Radioimmunoassay was used to measure plasma Ang level in mice . Results :Compared with normal WT control mice ,there were significant down‐regulations of BDNF protein expres‐sion [ (1 ± 0.16) vs .(0.54 ± 0.16)] in hippocampus and plasma Ang‐ (1‐7) level [ (55.6 ± 7.5) pg/ml vs .(42.8 ± 5.8) pg/ml] ,and significant rise in ERK1/2 phosphorylation [ (1 ± 0.28) vs .(1.79 ± 0.29)] in ACE2 KO mice (P<0.01 all). After irbesartan treatment ,there were significant rise in BDNF protein expression (0.88 ± 0.13) in hippocampus and plasma Ang‐ (1‐7) level [(59.4 ± 8.4) pg/ml] ,and significant reduction in ERK1/2 phosphoryla‐tion level (1.33 ± 0.19) in ACE2 KO mice (P<0.05 or <0.01) .Conclusion:There are BDNF protein expression down‐regulation and enhanced ERK1/2 phosphorylation in hippocampus of ACE2 KO mice. AT1 receptor blockade irbesartan can improve Ang‐ (1‐7 ) level and hippocampus BDNF expression , while reducing hippocampus ERK phosphorylation signal in ACE2 KO mice ,suggesting that AT1 receptor blockade possesses certain brain protective effect.

AIM:To investigate regulatory roles of Apelin in adventitial remodeling and fibrosis in rats with transverse aortic constriction ( TAC) .METHODS:The male Sprague-Dawley rats with TAC were randomized to daily deliver either pyroglutamyl Apelin-13 ( 50μg/kg) or saline for 4 weeks.RESULTS:Histomorphometric analysis by HE and Masson Trichrome staining revealed increased medi -al and adventitial thicknesses , especially in the adventitia , in ascending aortas in rats with TAC when compared with the sham-operated rats.Downregulation of APJ receptor and elevations in phosphorylated mTOR and ERK 1/2 levels were observed in rats with TAC . There are marked increases in heart weight ( HW) , HW/body weight ratio , and aortic fibrosis in rats with TAC .The pressure over-load-mediated pathological adventitial remodeling was strikingly rescued by Apelin-13, associated with attenuation of aortic fibrosis and reduced mRNA expression of TGF-β1, fibronectin and collagen I .CONCLUSION:Our results demonstrate the importance of Apelin-13 in amelioration of aortic adventitial remodeling and fibrosis in rats with TAC via modulation of the mTOR /ERK signaling , thus indi-cating potential therapeutic strategies by enhancing Apelin /APJ action for preventing pressure overload-and fibrosis-associated cardio-vascular disorders .

Objective To study whether SGK1 is involved in the phenotypic transformation in adventitial fibroblasts (AF).Methods Vascular AF were separated from the thoracic aortas of SD rats.The AF not stimulated with TGF-β1 were divided into blank group,control group 1 and control group 2.The AF induced with 2.5,5.0,10.0 and 15.0 ng/ml TGF-β1 were divided into groups A-D.The AF pretreated with 50 μmol/1 EMD638683 and SB203580 were divided into inhibitor group 1 and inhibitor group 2.The AF stimulated with 5 ng/ml TGF-β1 were divided into stimulation group 1 and stimulation group 2.The expression of SGK1,α-SMA and collagen Ⅰ was detected by Western blot.Results The expression of SGK1 was significantly higher in groups AC than in blank group.The expression of α-SMA was significantly higher in groups B-D than in controlgroup (P＜0.05).The α-SMA and collage Ⅰ expression levels were significantly higher in stimulation group 1 than in control group 1,and were significantly lower in inhibitor group 1 than in stimulation group 1 (P＜0.05).The SGK1 expression level was significantly higher in stimulation group 2 than in control group 2 and was significantly lower in inhibitor group 2 than in stimulation group 2 (P＜0.05).Conclusion SGK1 participates in TGF-β1-induced phenotypic transformation via p38 MAPK and is thus involved in vascular remodeling.

Objective: To verify whether the enzymatic activity of kynureninase (KYNU) could be changed by the Arg188Gln (G/A) mutation. Methods: The total RNA of human hepatic tissue was extracted and the KYNU gene cDNA was amplified by RT-PCR. Primers were designed according to the sequences around the site Arg188Gln of KYNU gene and the Arg188Gln (G/A) mutant KYNU cDNA was generated by site-directed mutagenesis. Both the wild-type and mutant-type KYNU genes were subcloned into pcDNA vectors and the recombinant plasmids were constructed. After being transfected into human embryonic kidney 293 (HEK293) cells, the expression of KYNU recombinant plasmids were assessed by Western blot. The enzymatic activities of KYNU were detected by high performance liquid chromatography (HPLC). Results: The KYNU enzyme activities were expressed in both wild and mutant HEK293 cells. Michaelis constants (Km) of the wild and mutant KYNU were (9.833±0.513) μmol/L and (29.900±0.265) μmol/L, respectively (P<0.05). The maximum velocities (Vmax) of the wild and mutant KYNU were (0.700±0.096) nmol·mg^-1·min^-1 and (0.084±0.003) nmol·mg^-1·min^-1, respectively (P<0.05). Conclusion: Arg188Gln (G/A) mutation can decrease the enzymatic activity of KYNU.
Arginine ; genetics ; Enzyme Activation ; genetics ; HEK293 Cells ; Humans ; Hydrolases ; genetics ; metabolism ; Mutation ; Plasmids