OBJECTIVETo study the effects of swimming exercise on the expression of apelin and its receptor (APJ) system in pulmonary tissues of rats with pulmonary hypertension induced by hypoxia.

METHODSForty-five male SD rats were randomly divided into control group, hypoxia group (seven-week) and swimming group (four-week swimming group after three-week hypoxia). The animal model of hypoxic pulmonary hypertension was established by exposing the rats to isobaric hypoxic chamber (8 h/d, 6 d/w). The rats of swimming group swam 60 min/day, 7 d/week for 4 weeks after three-week hypoxia. The mean pulmonary arterial pressure (mPAP) and the mean carotid arterial pressure (mCAP) were measured by either right or left cardiac catheterization, and the weight ratio of right ventricule/left ventricle plus septum [RV/(LV + S)] were calculated. The Masson's trichrome stained lung specimens were used by light microscope to examine the vessel wall area/total area (WA/TA), vessel cavity area/total area (CA/TA) and media thickness of pulmonary arterioles (PAMT). Meanwhile, apelin/ APJ expressions were determined by Western blot and immunohistochemistry.

RESULTS(1) mPAP and RV/(LV + S) of hypoxia group were higher than those of control group by 73.6% and 31.2% (P < 0.01), and mPAP and RV/(LV + S) of swimming group were lower than those of hypoxia group by 21.1%and 8.9 % (P < 0.05), respectively. (2) Masson's trichrome staining revealed that WA/TA and PAMT of hypoxia group were higher than those of control group by 70.8% and 102%. However, WA/TA and PAMT of swimming group were lower than those of hypoxia group by 24.8% and 40.1% (all P < 0.01), respectively. CA/TA of hypoxia group was lower than that of control group by 15.1%, and CA/TA of swimming group was lower than that of hypoxia group by 10.3% (all P < 0.01). (3) Compared with control group, hypoxia group showed up-regulated apelin expression and down-regulated APJ expression in pulmonary tissues (all P < 0.01). Compared with hypoxia group, swimming group showed decreased apelin expression and elevated APJ expression in pulmonary tissues (all P < 0.01). (4) Apelin localized mainly in intracytoplasm of inflammatory cell and tunica adventitia of vessel, and APJ were in vascular intima and tunica externa and plasmalemma of inflammatory cell.

CONCLUSIONThe improving effect of swimming exercise on hypoxic pulmonary hypertension in rats could be mediated by regulating the pulmonary apelin/APJ system.

Animals ; Apelin ; Apelin Receptors ; Hypertension, Pulmonary ; metabolism ; Hypoxia ; metabolism ; Intercellular Signaling Peptides and Proteins ; metabolism ; Male ; Physical Conditioning, Animal ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; metabolism ; Swimming

OBJECTIVETo observe the change of apelin and its receptor (APJ) in the lung tissue of rats with pulmonary hypertension induced by monocrotaline and to explore its significance.

METHODSTwenty-five male SD rats were randomly divided into control group (n = 10) and monocrotaline group (n = 15). On the twenty-first day after the rats were intraperitoneally injected 60 mg/kg monocrotaline for monocrotaline group or equal volume vehicle for control group, the mean pulmonary artery pressure was measured by right heart catheterization. Histopathological study of lung tissue was done with hematoxylin-eosin (HE) and Masson's trichrome staining. The concentration of apelin in the plasma was measured by radioimmunoassay. The expressions of apelin/APJ proteins and genes in lung tissue were measured respectively by Western blot and reverse transcription polymerase chain reaction (RT-PCR).

RESULTSThe mean pulmonary arterial pressure, right ventricular hypertrophy, pulmonary vascular remodeling index, content of apelin protein in lung tissue of monocrotaline group were higher than those in control group. APJ protein and gene expression in monocrotaline group were significantly lower than those in control group (P < 0.01, P < 0.05), but apelin gene expression in the lung tissue between the two groups had no significant difference.

CONCLUSIONEndogenous apelin/APJ dysfunction may play an important role in the development of pulmonary hypertension induced by monocrotaline.

Animals ; Apelin ; Apelin Receptors ; Hypertension, Pulmonary ; chemically induced ; metabolism ; Intercellular Signaling Peptides and Proteins ; metabolism ; Lung ; metabolism ; Male ; Monocrotaline ; adverse effects ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; metabolism

OBJECTIVE: To interpret the pharmacology of quercetin in treatment of atherosclerosis (AS). METHODS: Fourteen apolipoprotein E-deficient (ApoE^-/-) mice were divided into 2 groups by a random number table: an AS model (ApoE^-/-) group and a quercetin treatment group (7 in each). Seven age-matched C57 mice were used as controls (n=7). Quercetin [20 mg/(kg·d)] was administered to the quercetin group intragastrically for 8 weeks for pharmacodynamic evaluation. Besides morphological observation, the distribution of CD11b, F4/80, sirtuin 1 (Sirt1) and P21 was assayed by immunohistochemistry and immunofluorescence to evaluate macrophage infiltration and tissue senescence. Ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MSC/MS) was performed to study the pharmacology of quercetin against AS. Then, simultaneous administration of an apelin receptor antagonist (ML221) with quercetin was conducted to verify the possible targets of quercetin. Key proteins in apelin signaling pathway, such as angiotensin domain type 1 receptor-associated proteins (APJ), AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), tissue plasminogen activator (TPA), uncoupling protein 1 (UCP1) and angiotensin II receptor 1 (AT1R), were assayed by Western blot. RESULTS: Quercetin administration decreased lipid deposition in arterial lumen and improved the morphology of ApoE^-/- aortas in vivo. Quercetin decreased the densities of CD11b, F4/80 and P21 in the aorta and increased the level of serum apelin and the densities of APJ and Sirt1 in the aorta in ApoE^-/- mice (all P<0.05). Plasma metabolite profiling identified 118 differential metabolites and showed that quercetin affected mainly glycerophospholipids and fatty acyls. Bioinformatics analysis suggested that the apelin signaling pathway was one of the main pathways. Quercetin treatment increased the protein expressions of APJ, AMPK, PGC-1α, TPA and UCP1, while decreased the AT1R level (all P<0.05). After the apelin pathway was blocked by ML221, the effect of quercetin was abated significantly, confirming that quercetin attenuated AS by modulating the apelin signaling pathway (all P<0.05). CONCLUSION Quercetin alleviated AS lesions by up-regulation the apelin signaling pathway.
Mice ; Animals ; Apelin ; Tissue Plasminogen Activator/metabolism* ; Quercetin/therapeutic use* ; AMP-Activated Protein Kinases/metabolism* ; Sirtuin 1/metabolism* ; Signal Transduction/physiology* ; Atherosclerosis/metabolism* ; Apolipoproteins E

OBJECTIVETo explore the effect of puerarin combined with felodipine on the mRNA and protein expression of apelin and APJ in renal tissue of renovascular hypertensive rat.

METHODSixty-two Sprague-Dawley rats were used, of which 8 rats were randomly chosen as sham-operation group. The remaining rats were made for the rat model with renovascular hypertension. The renovascular hypertensive rats were randomly divided into 5 groups as follows: 4 groups which were treated with felodipine (0.8 mg x kg(-1) x d(-1)), puerarin (50 mg x kg(-1) x d(-1)), puerarin combined with felodipine (puerarin 25 mg x kg(-1) x d(-1) + felodipine 0.4 mg x kg(-1) x d(-1)) or captopril combined with felodipine (captopril 15 mg x kg(-1) x d(-1) x felodipine 0.4 mg x kg(-1) x d(-1)), and 1 group which was treated with distilled water. Drugs or distilled water were administered for 8 weeks. The expression of apelin and APJ mRNA and protein in ischemic and non-ischemic kidneys was assessed by RT-PCR or Western blot.

RESULTCompared with sham-operation group, the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys in model group was increased significantly (P < 0.01); the expression of APJ mRNA and protein in ischemic kidneys had no significance, while that in non-ischemic kidneys was decreased (P < 0. 01). Compared with model group, the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys was decreased significantly in all drug-treated groups (P < 0.01); while that of APJ mRNA and protein in non-ischemic kidneys was upregulated (P < 0.01). Compared with felodipine group, the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys was decreased (P < 0.01 or P < 0.05) in the group treated with both puerarin and felodipine; and the expression of APJ mRNA and protein in ischemic kidneys did not reach significant level, however, that was upregulated in non-ischemic kidneys (P < 0.01 or P < 0.05).

CONCLUSIONPuerarin downregulates the expression of apelin mRNA and protein in ischemic and non-ischemic kidneys, and upregulates that of APJ mRNA and protein in non-ischemic kidneys. Combination of puerarin and felodipine enhances the above-mentioned effects and shows no significant difference versus the combination of felodipine and captopril. The results suggest that puerarin regulates blood pressure and protects target organ through apelin/APJ pathway and that puerarin has synergetic effects with CCB.

Animals ; Antihypertensive Agents ; pharmacology ; Apelin ; Apelin Receptors ; Blotting, Western ; Captopril ; pharmacology ; Drug Synergism ; Felodipine ; pharmacology ; Gene Expression ; drug effects ; Hypertension, Renovascular ; genetics ; metabolism ; Intercellular Signaling Peptides and Proteins ; genetics ; metabolism ; Ischemia ; Isoflavones ; pharmacology ; Kidney ; blood supply ; drug effects ; metabolism ; Male ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Vasodilator Agents ; pharmacology

OBJECTIVETo investigate whether ginsenoside-Rb1 (Gs-Rb1) inhibits the apoptosis of hypoxia cardiomyocytes by up-regulating apelin-APJ system and whether the system is affected by hypoxia-induced factor 1α (Hif-1α).

METHODSNeonatal rat cardiomyocytes were randomly divided into 6 groups: a control group, a simple CoCl group, a simple Gs-Rb1 group, a CoCl and Gs-Rb1 hypoxia group, a CoCl and 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) group, a CoCl and YC-1 group and a Gs-Rb1 group, in which YC-1 inhibits the synthesis and accelerates the degradation of Hif-1a. The concentration of CoCl, Gs-Rb1 and YC-1 was 500 μmol/L, 200 μmol/L and 5 μmol/L, respectively; the apoptosis ratio was analyzed with a flow cytometer; and apelin, APJ and Hif-1α were assayed with immunocytochemistry, Western blot assays and reverse transcription polymerase chain reaction (RT-PCR).

RESULTS(1) The anti-apoptosis effect of Gs-Rb1 on hypoxia cardiomyocytes was significantly inhibited by YC-1; (2) Hypoxia significantly up-graded the expression of mRNA and protein of apelin; this effect was further reinforced by Gs-Rb1 and significantly inhibited by YC-1; (3) Gs-Rb1 further strengthened the expression of APJ mRNA and APJ proteins once hypoxia occurred, which was significantly inhibited by YC-1; (4) Gs-Rb1 significantly increased the expression of Hif-1α, which was completely abolished by YC-1; (5) There was a negative relationship between AR and apelin (or APJ, including mRNA and protein), a positive correlation between apelin (or APJ) protein and Hif-1a protein, in hypoxia cardiomyocytes.

CONCLUSIONThe apelin-APJ system plays an important role in the anti-apoptosis effect of Gs-Rb1 on hypoxia neonatal cardiomyocytes, which was partly adjusted by Hif-1α.

Animals ; Animals, Newborn ; Apelin ; Apelin Receptors ; Cell Hypoxia ; drug effects ; Ginsenosides ; pharmacology ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Immunohistochemistry ; Intercellular Signaling Peptides and Proteins ; genetics ; metabolism ; Myocytes, Cardiac ; cytology ; drug effects ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats, Wistar ; Receptors, G-Protein-Coupled ; metabolism

OBJECTIVETo examine the change of puerarin on the expression of apelin and its receptor of the two-kidney, one-clip (2K1C) rats.

METHODTirty male Sprague-Dawley rats were randomly divided into normal control group (C), model group (M) and puerarin group (P). The mean of carotid arterial pressure (mCAP), mean of left ventricular end diastolic pressure (LVEDP), and the weight ratio of left ventricular mass (left ventricle plus septum) to bodyweight (LVM/BW) were measured to evaluate the model of 2K1C renal hypertension. The concentrations of apelin in the plasma and left ventricle (LV) were measured with radioimmunoassay. Apelin mRNA and APJ mRNA expressed in the LV were examined by reverse transcription-polymerase chain reaction (RT-PCR). The peptides of apelin and APJ expressed in the LV were detected with immunohistochemistry (IHC).

RESULTCompared with C group, the mCAP, LVEDP and LVM/BW of M group were higher 36.58%, 333.8% and 20.24%, respectively (P<0.05, P<0.01, P<0.01). Compared with M group, LVEDP and LVM/BW of P group were lower 65.24% and 13.12%, respectively (both P<0.05). However mCAP was of no significant difference between these two groups. The levels of apelin-36 in the plasma and LV of M group were respectively higher 18.56% and 207.38% than those of C group (both P<0.05), while ones of P group were lower 24.21% and 49.40% than those of M group (both P<0.05). The expressions of apelin mRNA and APJ mRNA at left ventricle tissues of 2K1C rats were higher 77.66% and 119.00% (both P<0.05) than those of C group. The ones of P group were lower 27.40% and 45.66% than those of M group (both P<0.01). The IHC results indicate that the expressions of apelin and APJ peptides at left ventricle tissues of 2K1C rats were higher 129.51% and 154.1% (both P<0.01) than those of C group, respectively. Whereas the ones of P group were lower 65.36% and 62.87% than those of M group (both P<0.01).

CONCLUSIONThrough regulating apelin/APJ system puerarin has protective effect on the development of left ventricular hypertrophy by renal hypertension.

Animals ; Apelin ; Apelin Receptors ; Carrier Proteins ; genetics ; metabolism ; Gene Expression ; drug effects ; Hypertension, Renal ; drug therapy ; metabolism ; physiopathology ; Hypertrophy, Left Ventricular ; prevention & control ; Immunohistochemistry ; Intercellular Signaling Peptides and Proteins ; Isoflavones ; therapeutic use ; Male ; Radioimmunoassay ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

Objective: To investigate the effect and mechanism of sacubitril/valsartan on left ventricular remodeling and cardiac function in rats with heart failure. Methods: A total of 46 SPF-grade male Wistar rats weighed 300-350 g were acclimatized to the laboratory for 7 days. Rats were then divided into 4 groups: the heart failure group (n=12, intraperitoneal injection of adriamycin hydrochloride 2.5 mg/kg once a week for 6 consecutive weeks, establishing a model of heart failure); heart failure+sacubitril/valsartan group (treatment group, n=12, intragastric administration with sacubitril/valsartan 1 week before the first injection of adriamycin, at a dose of 60 mg·kg^-1·d^-1 for 7 weeks); heart failure+sacubitril/valsartan+APJ antagonist F13A group (F13A group, n=12, adriamycin and sacubitril/valsartan, intraperitoneal injection of 100 μg·kg^-1·d^-1 APJ antagonist F13A for 7 weeks) and control group (n=10, intraperitoneal injection of equal volume of normal saline). One week after the last injection of adriamycin or saline, transthoracic echocardiography was performed to detect the cardiac structure and function, and then the rats were executed, blood and left ventricular specimens were obtained for further analysis. Hematoxylin-eosin staining and Masson trichrome staining were performed to analyze the left ventricular pathological change and myocardial fibrosis. TUNEL staining was performed to detect cardiomyocyte apoptosis. mRNA expression of left ventricular myocardial apelin and APJ was detected by RT-qRCR. ELISA was performed to detect plasma apelin-12 concentration. The protein expression of left ventricular myocardial apelin and APJ was detected by Western blot. Results: Seven rats survived in the heart failure group, 10 in the treatment group, and 8 in the F13A group. Echocardiography showed that the left ventricular end-diastolic diameter (LVEDD) and the left ventricular end-systolic diameter (LVESD) were higher (both P<0.05), while the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were lower in the heart failure group than in the control group (both P<0.05). Compared with the heart failure group, rats in the treatment group were featured with lower LVEDD and LVESD (both P<0.05), higher LVEF and LVFS (both P<0.05), these beneficial effects were reversed in rats assigned to F13A group (all P<0.05 vs. treatment group). The results of HE staining showed that the cardiomyocytes of rats in the control group were arranged neatly and densely structured, the cardiomyocytes in the heart failure group were arranged in disorder, distorted and the gap between cells was increased, the cardiomyocytes in the treatment group were slightly neat and dense, and cardiomyocytes in the F13A group were featured similarly as the heart failure group. Masson staining showed that there were small amount of collagen fibers in the left ventricular myocardial interstitium of the control group, while left ventricular myocardial fibrosis was significantly increased, and collagen volume fraction (CVF) was significantly higher in the heart failure group than that of the control group (P<0.05). Compared with the heart failure group, the left ventricular myocardial fibrosis and the CVF were reduced in the treatment group (both P<0.05), these effects were reversed in the F13A group (all P<0.05 vs. treatment group). TUNEL staining showed that the apoptosis index (AI) of cardiomyocytes in rats was higher in the heart failure group compared with the control group (P<0.05), which was reduced in the treatment group (P<0.05 vs. heart failure group), this effect again was reversed in the F13A group (P<0.05 vs. treatment group). The results of RT-qPCR and Western blot showed that the mRNA and protein levels of apelin and APJ in left ventricular myocardial tissue of rats were downregulated in heart failure group (all P<0.05) compared with the control group. Compared with the heart failure group, the mRNA and protein levels of apelin and APJ were upregulated in the treatment group (all P<0.05), these effects were reversed in the F13A group (all P<0.05 vs. treatment group). ELISA test showed that the plasma apelin concentration of rats was lower in the heart failure group compared with the control group (P<0.05); compared with the heart failure group, the plasma apelin concentration of rats was higher in the treatment group (P<0.05), this effect was reversed in the F13A group (P<0.05 vs. treatment group). Conclusion: Sacubitril/valsartan can partially reverse left ventricular remodeling and improve cardiac function in rats with heart failure through modulating Apelin/APJ pathways.
Aminobutyrates/pharmacology* ; Animals ; Apelin/metabolism* ; Biphenyl Compounds ; Collagen/metabolism* ; Doxorubicin/pharmacology* ; Fibrosis ; Heart Failure/pathology* ; Male ; Myocytes, Cardiac/pathology* ; RNA, Messenger/metabolism* ; Rats ; Rats, Wistar ; Valsartan/pharmacology* ; Ventricular Function, Left/drug effects* ; Ventricular Remodeling

OBJECTIVETo investigate the effect of apelin on vasodilatation of isolated pulmonary arterial rings in rats and its relationship to the nitric oxide (NO) pathway, and to observe the difference of vasodilatation between hypoxic rats and normoxic rats.

METHODSThirty-six male Sprague-Dawley (SD) rats were randomly divided into hypoxic group and normoxic group. The effects of accumulated apelin on pulmonary arterial rings preconstricted with norepinephrine (NE) were observed by using tissue organ bath system. After pulmonary arterial rings were pretreated with three methods: removing the endothelium, pretreating with nitric oxide synthase inhibitor L-NAME or soluble guanylatecyclase inhibitor ODQ, the different effect of apelin was observed. In addition, the difference of vasodilatation between hypoxic rats and normal rats were observed.

RESULTS(1) Exposure of intact endothelium pulmonary arterial rings preconstricted by NE to apelin at concentration (0.01 - 100 nmol/L) induced a significant concentration dependent relaxation. The maximal vasorelaxant effect of apelin was 10.62% +/- 2.60%, which was inhibited by removal of the endothelium (P < 0.01), pretreatment with L-NAME (P < 0.01) or ODQ (P < 0.01). (2) Response of pulmonary arterial rings from hypoxic pulmonary hypertension rats was decreased (P < 0.05). Compared to normal rats, at a concentration of 100 nmol/L, the response to apelin on arteries from hypoxic rats decreased 60.45% (P < 0.01). But the values of EC50 were not significantly different (P > 0.05).

CONCLUSIONThese results indicate that apelin relaxes the pulmonary arterial rings of rats in an endothelium dependent manner, which may have a relationship to NO signaling pathway. The response of vasodilatation is decreased in the pulmonary arterial rings from the hypoxic rats.

Animals ; Apelin ; Hypoxia ; physiopathology ; In Vitro Techniques ; Intercellular Signaling Peptides and Proteins ; pharmacology ; Male ; Nitric Oxide ; metabolism ; Pulmonary Artery ; physiopathology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Vasodilation ; drug effects

BACKGROUNDAs two novel adipocytokines, chemerin and apelin play a key role in the pathological process of insulin resistance (IR), glucose metabolism and obesity, researchers have found that the levels of chemerin and apelin changed significantly in type 2 diabetic patients with obesity, however, the underlying mechanism involved remains unclear. The aim of this study was to investigate whether chemerin and apelin play an important role in the pathophysiologic proceeding of diabetes.

METHODSThis study enrolled 81 newly diagnosed obese type 2 diabetes mellitus (T2DM) patients (T2DM group, n = 81). All the patients were randomly assigned to DM1 group treated with metformin (n = 41) and DM2 group treated with pioglitazone (n = 40). After hypoglycemic agents treatment, patients under better blood glucose control were chosen to be given antioxidant treatment. Another 79 subjects without T2DM were recruited as normal control group (NC group), including 40 subjects (NC1 group) with normal body mass index (BMI) and 39 obese subjects (NC2 group). Levels of chemerin, apelin, BMI, tumor necrosis factor-α (TNF-α), homeostasis model assessment of IR (HOMA-IR) and 8-isoprotaglandim F2α (8-iso-PGF2α) were examined at baseline and post-treatment. The relationship between chemerin, apelin and BMI, TNF-α, HOMA-IR, 8-iso-PGF2α was analyzed.

RESULTSThe baseline levels of chemerin, apelin, TNF-α, HOMA-IR and 8-iso-PGF2α in T2DM group were significantly higher than normal control group (P < 0.001). All indices mentioned above were significantly decreased after treatment (P < 0.05). In T2DM patients treated with pioglitazone, indices mentioned above except for HOMA-IR, were decreased significantly compared with patients treated with metformin (P < 0.05). After antioxidant treatment using lipoic acid, levels of chemerin, apelin, TNF-α and 8-iso-PGF2α were further significantly decreased (P < 0.05). Correlation analysis showed that the levels of chemerin and apelin correlated positively with BMI, TNF-α, HOMA-IR and 8-iso-PGF2α before and after treatment with hypoglycemic agents (P < 0.01). The levels of chemerin and apelin also had positive correlation with TNF-α and 8-iso-PGF2α after antioxidant treatment (P < 0.05).

CONCLUSIONSThe levels of chemerin and apelin in obese T2DM patients are closely related to IR. The increased levels may be a result of compensatory response to IR, and also may be the causative factor of IR. The levels of chemerin and apelin correlate closely with oxidative stress and inflammation. The two adipokines may be inflammatory factors playing important roles in the initiation and development of obese T2DM. Chemerin and apelin are related to the pathophysiology of IR, oxidative stress and inflammation.

Apelin ; Blood Glucose ; metabolism ; Body Mass Index ; Chemokines ; metabolism ; Diabetes Mellitus, Type 2 ; drug therapy ; immunology ; metabolism ; Dinoprost ; analogs & derivatives ; metabolism ; Humans ; Hypoglycemic Agents ; therapeutic use ; Inflammation ; metabolism ; Intercellular Signaling Peptides and Proteins ; metabolism ; Metformin ; therapeutic use ; Thiazolidinediones ; therapeutic use ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo investigate the effect of nitric oxide (NO) on the expression of apelin receptor mRNA, as well as their correlation, in the caudate nucleus of rat.

METHODSL-Arginine (L-Arg), N(G)-nitro-L-arginine methyl ester (L-NAME) and normal saline (NS) was separately microinjected into rat caudate nucleus. Expressions of neuronal NO synthase (nNOS) mRNA and apelin receptor mRNA were detected by RT-PCR at 4, 8, 12, 24 and 48 h after microinjection, and their correlation was determined.

RESULTSThe expressions of nNOS mRNA and apelin receptor mRNA were both significantly increased after microinjection of L-Arg, but significantly decreased after microinjection of L-NAME compared with the NS control group. The nNOS mRNA had a positive correlation with the expression of apelin receptor mRNA after microinjection of L-Arg and L-NAME.

CONCLUSIONThe activity of NOS in the central nervous system, especially in the caudate nucleus, is one of the key factors for NO to exert many kinds of biological actions, such as modulation of central pain, as a neurotransmitter. The neurobiological action of NO in rat caudate nucleus may be associated with apelin receptors.

Animals ; Apelin Receptors ; Arginine ; pharmacology ; Caudate Nucleus ; drug effects ; metabolism ; Enzyme Inhibitors ; pharmacology ; Gene Expression Regulation ; drug effects ; physiology ; Male ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; physiology ; Nitric Oxide Synthase Type I ; metabolism ; RNA, Messenger ; Rats ; Rats, Wistar ; Receptors, G-Protein-Coupled ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; methods