Thyroid hormone–sympathetic interaction and adaptive thermogenesis are thyroid hormone receptor isoform–specific

In newborns and small mammals, cold-induced adaptive (or nonshivering) thermogenesis is produced primarily in brown adipose tissue (BAT). Heat production is stimulated by the sympathetic nervous system, but it has an absolute requirement for thyroid hormone. We used the thyroid hormone receptor-beta--selective (TR-beta--selective) ligand, GC-1, to determine by a pharmacological approach whether adaptive thermogenesis was TR isoform--specific. Hypothyroid mice were treated for 10 days with varying doses of T3 or GC-1. The level of uncoupling protein 1 (UCP1), the key thermogenic protein in BAT, was restored by either T3 or GC-1 treatment. However, whereas interscapular BAT in T3-treated mice showed a 3.0 degrees C elevation upon infusion of norepinephrine, indicating normal thermogenesis, the temperature did not increase (<0.5 degrees C) in GC-1--treated mice. When exposed to cold (4 degrees C), GC-1--treated mice also failed to maintain core body temperature and had reduced stimulation of BAT UCP1 mRNA, indicating impaired adrenergic responsiveness. Brown adipocytes isolated from hypothyroid mice replaced with T3, but not from those replaced with GC-1, had normal cAMP production in response to adrenergic stimulation in vitro. We conclude that two distinct thyroid-dependent pathways, stimulation of UCP1 and augmentation of adrenergic responsiveness, are mediated by different TR isoforms in the same tissue.     

Induction of rat uncoupling protein-2 gene treated with tumour necrosis factor alpha in vivo

BACKGROUND: The cytokine tumour necrosis factor (TNF) alpha has been reported to induce metabolic abnormalities such as anorexia and thermogenesis. To investigate functional modulators of uncoupling protein-2 (UCP2) gene expression, we examined the effects of TNF-alpha on UCP2 mRNA expression in rats. METHODS: Mature male Wistar King A (WKA) rats at 10-11 weeks of age were treated with recombinant human TNF-alpha at a dose of 0.6 nmol 100 g-1 body weight by intraperitoneal administration. RESULTS: TNF-alpha treatment induced an increase in UCP2 mRNA expression in broadly distributed tissues including brown adipose tissue (BAT), white adipose tissue (WAT) and skeletal muscle, and an elevation of ob gene mRNA expression in WAT. After the TNF-alpha treatment, an increase in plasma leptin concentration occurred in an ob gene-dependent manner, accompanied by an anorectic effect. CONCLUSION: The present results provide evidence for a new regulatory loop involving TNF-alpha and UCP2, and add novel insights into the regulatory mechanisms of energy homeostasis.     

Bofutsushosan, an Oriental Herbal Medicine, Attenuates the Weight Gain of White Adipose Tissue and the Increased Size of Adipocytes Associated with the Increase in Their Expression of Uncoupling Protein 1 in High-Fat Diet-Fed Male KK/Ta mice

Bofutsushosan (BOF), an oriental herbal medicine, has been used as an anti-obesity drug in overweight patients. In the present study, to evaluate the anti-obesity and anti-diabetic effects of BOF, we investigated the effects of BOF on the white adipose tissue (WAT) weight, the size of adipocytes, adiponectin expression, and oral glucose tolerance test results in high-fat diet-fed male KK/Ta mice. In addition, the mRNA expression levels of uncoupling protein 1 (UCP1) and UCP2 mRNA in WAT and brown adipose tissue (BAT) were measured. 6-week-old KK/Ta mice were divided into four groups and fed a purified powdered basal diet (the BD group), a purified high-fat (HF) powdered diet containing suet powder at 37.5 g/100 g diet (the HF group), a high-fat diet plus 1.0% bofutsushosan (BOF) treatment (the HF + BOF group), or a high-fat diet plus 1.0% daisaikoto (DAI) treatment (the HF + DAI group) for 4 weeks. The weight of WAT and the size of adipocytes were increased in the HF group compared with those in the BD group, and these increases in the HF group were significantly inhibited in the HF + BOF group, but not affected in the HF + DAI group. There were no statistically significant differences in plasma levels and tissue mRNA levels of adiponectin among the four groups. There were no significant differences in UCP1 mRNA expression of BAT among the four groups. The expression of UCP1 mRNA in WAT was found in the HF + BOF group, but little expression was seen in the WAT of the BD, HF, or HF + DAI groups. The elevated plasma glucose levels and responses after the glucose loading in the HF group tended to decrease in the HF + BOF group. These results suggest that BOF decreases the weight and size gains of WAT along with up-regulating UCP1 mRNA in WAT in high-fat diet-fed mice.     

Intracellular conversion of thyroxine to triiodothyronine is required for the optimal thermogenic function of brown adipose tissue.

The effect of thyroxine (T4) and triiodothyronine (T3) on the expression of uncoupling protein (UCP) in rat brown adipose tissue (BAT) has been examined. Thyroidectomized rats have a threefold reduction in basal UCP levels. When exposed to cold, they become hypothermic and show a fivefold lower response of UCP than euthyroid controls. T3 augments the basal levels and the response of UCP and its mRNA to cold in a dose-dependent manner. However, to normalize the response of UCP, T3 has to be given in a dosage that produces systemic hyperthyroidism. Mere T3 replacement corrects the systemic hypothyroidism but not the hypothermia or the low levels of UCP. In contrast, replacement doses of T4 prevent the hypothermia and correct the UCP level. Both effects of T4 are blocked by preventing T4 to T3 conversion in BAT. Thus, the optimal UCP response to cold and protection against hypothermia require a high BAT T3 concentration, which is attained from euthyroid levels of T4 via the activation of the BAT T4 5'deiodinase during cold exposure, but not from euthyroid plasma T3 levels.     

The type 2 iodothyronine deiodinase is essential for adaptive thermogenesis in brown adipose tissue

Type 2 iodothyronine deiodinase (D2) is a selenoenzyme, the product of the recently cloned cAMP-dependent Dio2 gene, which increases 10- to 50-fold during cold stress only in brown adipose tissue (BAT). Here we report that despite a normal plasma 3,5,3'-triiodothyronine (T3) concentration, cold-exposed mice with targeted disruption of the Dio2 gene (Dio2(-/-)) become hypothermic due to impaired BAT thermogenesis and survive by compensatory shivering with consequent acute weight loss. This occurs despite normal basal mitochondrial uncoupling protein 1 (UCP1) concentration. In Dio2(-/-) brown adipocytes, the acute norepinephrine-, CL316,243-, or forskolin-induced increases in lipolysis, UCP1 mRNA, and O(2) consumption are all reduced due to impaired cAMP generation. These hypothyroid-like abnormalities are completely reversed by a single injection of T3 14 hours earlier. Recent studies suggest that UCP1 is primarily dependent on thyroid hormone receptor beta (TR beta) while the normal sympathetic response of brown adipocytes requires TR alpha. Intracellularly generated T3 may be required to saturate the TR alpha, which has an approximately fourfold lower T3-binding affinity than does TR beta. Thus, D2 is an essential component in the thyroid-sympathetic synergism required for thermal homeostasis in small mammals.     

Is acute morphine hyperthermia of unrestrained rats due to selective activation of brown adipose tissue thermogenesis?

Experiments were conducted to determine if the hyperthermia after acute morphine sulfate (MS) administration was due to selective activation of brown adipose tissue (BAT) thermogenesis. Interscapular BAT temperature (TIBAT) and core (rectal) temperature (TR) were measured concurrently in groups of unrestrained, male Sprague-Dawley rats kept at 21.0 degrees C before and after i.p. (0.75, 2.0 or 10.0 mg/kg) or intracerebroventricular injections (200 ng- greater than 5 ul) of MS or sterile saline. TRS and TIBATS increased 0.6-1.0 degree C after i.p. intracerebroventricular injections of MS but the time course and magnitude of the changes in TIBATS from mean preinjections readings were not different from the increases in TRS. By contrast, isoproterenol HCl (0.5 mg/kg i.p.), known to activate BAT heat production, given to rats kept at 4 or 21 degrees C raised the TIBATS significantly above changes seen in TRS. Rats given MS in which the capacity for brown fat heat production had been increased previously (cold adaptation) or decreased (fasting or bilateral denervation) again evoked increases in TIBAT and TRS that were not significantly different from one another or from the response of warm-adapted, normophagic controls. Furthermore, oxygen uptakes were reduced after MS compared to oxygen uptakes after saline injections. [3H]Guanosine diphosphate binding to interscapular BAT mitochondria isolated from rats sacrificed at peak morphine hyperthermia (greater than 1.0 degree C) was not different from that of saline control animals. The results indicate clearly that the hyperthermia occurring in unrestrained rats after acute central or peripheral opiate administration is not due to selective activation of BAT thermogenesis.     

Increased uncoupling protein-2 and -3 mRNA expression during fasting in obese and lean humans.

Uncoupling protein-2 and -3 (UCP2 and UCP3) are mitochondrial proteins that show high sequence homology with the brown adipocyte-specific UCP1. UCP1 induces heat production by uncoupling respiration from ATP synthesis. UCP2 is widely expressed in human tissues, whereas UCP3 expression seems restricted to skeletal muscle, an important site of thermogenesis in humans. We have investigated the regulation of UCP2 and UCP3 gene expression in skeletal muscle and adipose tissue from lean and obese humans. UCP2 and -3 mRNA levels were not correlated with body mass index (BMI) in skeletal muscle, but a positive correlation (r = 0.55, P < 0.01, n = 22) was found between UCP2 mRNA level in adipose tissue and BMI. The effect of fasting was investigated in eight lean and six obese subjects maintained on a hypocaloric diet (1,045 kJ/d) for 5 d. Calorie restriction induced a similar 2-2.5-fold increase in UCP2 and -3 mRNA levels in lean and obese subjects. To study the effect of insulin on UCP gene expression, six lean and five obese subjects underwent a 3-h euglycemic hyperinsulinemic clamp. Insulin infusion did not modify UCP2 and -3 mRNA levels. In conclusion, the similar induction of gene expression observed during fasting in lean and obese subjects shows that there is no major alteration of UCP2 and -3 gene regulation in adipose tissue and skeletal muscle of obese subjects. The increase in UCP2 and -3 mRNA levels suggests a role for these proteins in the metabolic adaptation to fasting.     

Roles of norepinephrine, free Fatty acids, thyroid status, and skeletal muscle uncoupling protein 3 expression in sympathomimetic-induced thermogenesis

Thyroid hormone (TH) plays a fundamental role in thermoregulation, yet the molecular mediators of its effects are not fully defined. Recently, skeletal muscle (SKM) uncoupling protein (UCP) 3 was shown to be an important mediator of the thermogenic effects of the widely abused sympathomimetic agents 3,4-methylenedioxymethamphetamine (MDMA; Ecstasy) and methamphetamine. Expression of UCP3 is regulated by TH. Activation of UCP3 is indirectly regulated by norepinephrine (NE) and is dependent upon the availability of free fatty acids (FFAs). We hypothesized that UCP3 may be a molecular link between TH and hyperthermia, requiring increased levels of both NE and FFAs to accomplish the thermogenic effect. Here, we demonstrate that MDMA (40 mg/kg s.c.) significantly increases plasma FFA levels 30 min after treatment. Pharmacologically increasing NE levels through the inhibition of phenylethanolamine N-methyltransferase with +/-2,3-dichloro-alpha-methylbenzylamine potentiated the hyperthermic effects of a 20 mg/kg dose of MDMA. Using Western blots and regression analysis, we further illustrated that chronic hyperthyroidism in rats potentiates the hyperthermic effects of MDMA and increases levels of SKM UCP3 protein in a linear fashion according to levels of circulating plasma TH. Conversely, chronic hypothyroidism results in a hypothermic response to MDMA that is directly proportionate to decreased UCP3 expression. Acute TH supplementation did not change the skeletal muscle UCP3 expression levels or temperature responses to MDMA. These findings suggest that, although MDMA-induced hyperthermia appears to result from increased NE and FFA levels, susceptibility is ultimately determined by TH regulation of UCP3-dependent thermogenesis.     

Pharmacokinetics of intraperitoneal piperacillin/tazobactam in patients on peritoneal dialysis with and without pseudomonas peritonitis.

OBJECTIVE: The objective of this study was to assess the pharmacokinetics of intraperitoneal (IP) administration of the antibiotic combination piperacillin/tazobactam (PIP/TAZ) to patients on chronic ambulatory peritoneal dialysis (CAPD) with and without pseudomonas peritonitis. DESIGN: Open-labeled study. SETTING: The study was carried out in the CAPD unit of Assaf Harofeh Medical Center, Zerifin, Israel. PATIENTS AND METHODS: Six patients participated in the study, 4 had pseudomonas peritonitis, all were given an IP loading dose of 4 g/0.5 g PIP/TAZ. Twenty-four hours after the initial dose, a maintenance dose of 0.5 g/0.0625 g PIP/TAZ was administered with each dialysate exchange for a period of 1 week. The patients without peritonitis received only the loading dose. High performance liquid chromatography was used to determine the concentrations of PIPITAZ in plasma obtained at 0, 30, 60, 90, 120, 360, 480, 600, 720, and 1440 minutes after administration. Samples of the dialysate fluid for determination of PIP/TAZ concentration were collected at 6,10,14, 24, and 72, 120, and 168 hours. RESULTS: After the loading dose, the highest plasma PIP concentration (Cmax) was 51.6 t 21.25 Lig/mL and appeared at 1.5 = 0.45 hours (t,,a). During the maintenance period plasma PIP concentration was 5.2 t 4.75 Lg/mL. Tazobactam was detected in the plasma of 1 patient only. The concentration of TAZ in the dialysate fluid during the maintenance period was 2.3 t 0.5 ig/mL. CONCLUSIONS: Piperacillin administered IP at 4 g reached plasma concentrations comparable to intravenous administration and considered therapeutic (above the MIC90 for Pseudomonas aeruginosa) in CAPD patients with or without peritonitis.The maintenance dose, however, should be augmented. Tazobactam could not be detected in the plasma of most patients and the therapeutic implications of IP administration of TAZ cannot be directly correlated to intravenous administration.     

p62 Links β-adrenergic input to mitochondrial function and thermogenesis

The scaffold protein p62 (sequestosome 1; SQSTM1) is an emerging key molecular link among the metabolic, immune, and proliferative processes of the cell. Here, we report that adipocyte-specific, but not CNS-, liver-, muscle-, or myeloid-specific p62-deficient mice are obese and exhibit a decreased metabolic rate caused by impaired nonshivering thermogenesis. Our results show that p62 regulates energy metabolism via control of mitochondrial function in brown adipose tissue (BAT). Accordingly, adipocyte-specific p62 deficiency led to impaired mitochondrial function, causing BAT to become unresponsive to β-adrenergic stimuli. Ablation of p62 leads to decreased activation of p38 targets, affecting signaling molecules that control mitochondrial function, such as ATF2, CREB, PGC1α, DIO2, NRF1, CYTC, COX2, ATP5β, and UCP1. p62 ablation in HIB1B and BAT primary cells demonstrated that p62 controls thermogenesis in a cell-autonomous manner, independently of brown adipocyte development or differentiation. Together, our data identify p62 as a novel regulator of mitochondrial function and brown fat thermogenesis.     

Histamine induces the expression of uncoupling protein 2 (UCP2) and acid-binding protein (aP2) in white adipocytes.

BACKGROUND: The aim of the present study was to investigate whether histamine induces up-regulated expression of uncoupling protein 2 (UCP2) and fat acid-binding protein (aP2) in white adipocytes (differentiated 3T3-L1 cells). METHODS: Differentiation of 3T3-L1 preadipocytes to adipocytes was induced by the addition of 5 microg/mL insulin, 1 micromol/L dexamethasone, 10 mmol/L 1-isobutyl-3-methylxanthine, 1% dimethylsulfoxide, and 10% fetal bovine serum in Dulbecco's modification of Eagle's medium. Total RNA from differentiated 3T3-L1 cells was extracted and semi-quantitative RT-PCR was performed to determine the levels of UCP2 and aP2 mRNA. The expression level of UCP2 protein was determined by Western blot analysis. RESULTS: Histamine at a concentration of 30 micromol/L significantly increased the expression of UCP2 mRNA and UCP2 protein, and expression levels reached a peak value. There were significant differences in the expression levels of UCP2 mRNA and UCP2 protein in adipocytes treated with 30 micromol/L histamine at various time points within 48 h, and their levels reached a peak value after 6 h of incubation. In addition, histamine increased the expression level of aP2 mRNA in adipocytes. Expression of aP2 mRNA in adipocytes reached the highest value at a concentration of 20 micromol/L histamine after 6-h incubation. Finally, we found that diphenhydramine (a H1 receptor antagonist) significantly decreased expression levels of UCP2 mRNA and protein, as well as aP2 mRNA. There were significant differences in expression levels of UCP2 and aP2 mRNA in adipocytes treated at concentrations of 20 micromol/L histamine and diphenhydramine, respectively. CONCLUSIONS: These data reveal that histamine up-regulated the expression of UCP2 and aP2 in vitro in white adipocytes.     

汉防己甲素干预K562细胞mdr1基因表达的研究

目的 观察汉防己甲素(TTD)对阿霉素诱导的K562细胞mdr1基因表达的影响,并初步探讨其机制.方法 采用MTT法观察TTD对K562细胞的毒性作用,以0.6μg/ml阿霉素单独作用或0.6μg/ml阿霉素联合不同浓度的TTD(0.5、1.0、2.0μg/ml)作用于K562细胞,用RT-PCR法检测mdr1 mRNA、NF-kB mRNA水平,用流式细胞术检测P-gP的表达情况,用胞内罗丹明123(Rho123)积聚试验检测P-gP的功能.结果 空白对照K562细胞未见明显mdr1 mRNA及P-gP表达(水平分别为0.171±0.012、7.85±0.15),细胞内Rho123平均荧光强度(反映P-gP功能)为711.9±63.6,NF-kBmRNA水平为0.783±0.090;0.6μg/ml阿霉素作用24 h后mdr1 mRNA、P-gP、NF-kB mRNA表达上调为0.428±0.012、73.68±1.84、1.075±0.047,细胞内Rho123平均荧光强度下降为347.8±60.6(P值均＜0.05);2.0μg/ml TTD预作用24 h再与0.6 μg/ml阿霉素联合作用24 h能显著抑制阿霉素诱导的mdr1 mRNA、P-gp表达及功能、NF-kB mRNA的上调(分别为0.148±0.006、7.18 ±0.38、799.7±45.8、0.627±0.098)(P＜0.05),而0.5、1.0μg/TTD无明显影响.结论 TTD以浓度依赖性的方式干预阿霉素诱导的mdr1 mRNA、P-gp表达和P-gp功能的上调,其机制可能与TTD抑制了阿霉素诱导的NF-kB的表达有关.     

阿霉素对K562细胞Gfi-1表达的影响及其与相关凋亡基因关系的研究

本研究探讨阿霉素体外作用于K562细胞的细胞效应及癌基因Gfi-1和相关凋亡基因表达变化的机制。用不同浓度的阿霉素作用于K562细胞24小时,然后应用DNA电泳和流式细胞术检测K562细胞凋亡;用RT-PCR、流式细胞术检测Gfi-1、Bcl-2、bax基因和蛋白表达的变化。结果表明：当阿霉素浓度在0、0.5、2.0mg/L作用K562细胞24小时,细胞凋亡增加,可见典型的DNA断裂电泳条带;同时,当ADM浓度自0.5增为2.0mg/L时,Gfi-1表达减少,bax表达增加;Bcl-2表达在ADM0.5-2.0mg/L之间变化不明显,mRNA及蛋白水平均无统计学差异;当阿霉素浓度大于2.0mg/L时,细胞凋亡率并不增加,而是下降,且出现细胞坏死。结论：一定浓度阿霉素能诱导K562细胞凋亡,细胞凋亡率表达的变化与阿霉素浓度呈一定的量效依赖关系,阿霉素诱导K562细胞凋亡可能与抑制Gfi-1基因的表达和激活bax基因的表达有一定的关系。     

氯胺酮对大鼠脑缺血后解偶联蛋白2的影响

目的 探讨氧胺酮对大鼠前脑缺血-再灌注(I/R)后海马解偶联蛋白2(uncoupling proteins 2,UCP 2)表达的影响及在脑保护作用中的机制. 方法 45只体质量在250～300 g的雄性Wistar大鼠随机分为3组,每组15只.双侧颈总动脉夹闭加放血降压再回输法建立前脑缺血-再灌注模型,大鼠脑电图出现低幅持续性7 Hz、30～40μV的θ节律为脑缺血模型成功标志.对照组(C组):仅暴露双侧颈总动脉,未放血降压及夹闭双侧颈总动脉;缺血损伤组(1组):放血法使平均动脉压降到(40±5)mmHg时,夹闭双侧颈总动脉10 min,侧脑室内注射生理盐水(1.0 mg/kg);氯胺酮干预组(K组):放血降压、夹闭双侧颈总动脉与Ⅰ组相同,侧脑室内注射氯胺酮(1.0 mg/kg).于再灌注6 h后断头取脑组织,光镜下观察脑组织病理学改变;半定量逆转录.聚合酶链反应(RT-PCR)技术检测海马UCP 2mRNA表达(n=7);免疫组织化学(IH)法检测海马UCP2蛋白表达(n=8).RT-PCR、IH结果应用方差分析(ANOVA)进行统计学分析. 结果 与C组UCP2 mRNA(0,91±0.02)表达比较,Ⅰ组脑I/R后6h UCP2 mRNA(1.06±0.02)和K组脑I/R后6 h UCP2 mRNA(1.18±0.06)表达升高(P<0.05),K组脑I/R后6 h UCP 2 mRNA表达高于Ⅰ组(P<0.05);C组UCP2蛋白少量表达(17.91±5.49),Ⅰ组脑I/R后6 h UCP2蛋白(31.56±4.01)和K组脑I/R后6 h UCP2蛋白(44.61±4.96)表达升高(P<0.05).K组脑I/R后6 h UCP2蛋白表达高于Ⅰ组(P<0.05). 结论 氯胺酮促进大鼠前脑缺血-再灌注(I/R)后海马UCP 2 mRNA和蛋白的表达,可能是其对脑缺血-再灌注损伤保护作用的机制之一.     

Cardiac natriuretic peptides act via p38 MAPK to induce the brown fat thermogenic program in mouse and human adipocytes

The ability of mammals to resist body fat accumulation is linked to their ability to expand the number and activity of "brown adipocytes" within white fat depots. Activation of β-adrenergic receptors (β-ARs) can induce a functional "brown-like" adipocyte phenotype. As cardiac natriuretic peptides (NPs) and β-AR agonists are similarly potent at stimulating lipolysis in human adipocytes, we investigated whether NPs could induce human and mouse adipocytes to acquire brown adipocyte features, including a capacity for thermogenic energy expenditure mediated by uncoupling protein 1 (UCP1). In human adipocytes, atrial NP (ANP) and ventricular NP (BNP) activated PPARγ coactivator-1α (PGC-1α) and UCP1 expression, induced mitochondriogenesis, and increased uncoupled and total respiration. At low concentrations, ANP and β-AR agonists additively enhanced expression of brown fat and mitochondrial markers in a p38 MAPK-dependent manner. Mice exposed to cold temperatures had increased levels of circulating NPs as well as higher expression of NP signaling receptor and lower expression of the NP clearance receptor (Nprc) in brown adipose tissue (BAT) and white adipose tissue (WAT). NPR-C(-/-) mice had markedly smaller WAT and BAT depots but higher expression of thermogenic genes such as Ucp1. Infusion of BNP into mice robustly increased Ucp1 and Pgc-1α expression in WAT and BAT, with corresponding elevation of respiration and energy expenditure. These results suggest that NPs promote "browning" of white adipocytes to increase energy expenditure, defining the heart as a central regulator of adipose tissue biology.     

Interleukin 1 (IL-1) gene expression, synthesis, and effect of specific IL-1 receptor blockade in rabbit immune complex colitis.

Interleukin 1 (IL-1) may be a key mediator of inflammation and tissue damage in inflammatory bowel disease (IBD). In rabbits with immune complex-induced colitis, IL-1 alpha and beta mRNA levels were detectable at 4 h, peaked at 12 but were absent at 96 h after the induction of colitis. Colonic IL-1 tissue levels were measured by specific radioimmunoassays. IL-1 alpha was significantly elevated at 4 h (9.4 +/- 1.5 ng/g colon), progressively increased at 48 h (31 +/- 5.8 ng/g) and then decreased by 96 h (11.5 +/- 3.4 ng/g). IL-1 beta levels were 2.0 +/- 0.5 ng/g colon at 4 h, 5.0 +/- 1.6 ng/g at 48 h and undetectable by 96 h. By comparison, colonic levels of PGE2 and LTB4 were unchanged during the first 12 h and did not become elevated until 24 h. IL-1 alpha levels were highly correlated with inflammation (r = 0.885, P less than 0.0001), edema (r = 0.789, P less than 0.0001) and necrosis (r = 0.752, P less than 0.0005). Treatment with a specific IL-1 receptor antagonist (IL-1 ra) before and during the first 33 h after the administration of immune complexes markedly reduced inflammatory cell infiltration index (from 3.2 +/- 0.4 to 1.4 +/- 0.3, P less than 0.02), edema (from 2.2 +/- 0.4 to 0.6 +/- 0.3, P less than 0.01) and necrosis (from 43 +/- 10% to 6.6 +/- 3.2%, P less than 0.03) compared to vehicle-matched colitis animals. These studies demonstrate that (a) IL-1 gene expression and synthesis occur early in the course of immune complex-induced colitis; (b) are significantly elevated for 12 h before the appearance of PGE2 and LTB4; (c) tissue levels of IL-1 correlate with the degree of tissue inflammation and; (d) specific blockade of IL-1 receptors reduces the inflammatory responses associated with experimental colitis.     

缺氧诱导因子-1α对缺氧所致血管平滑肌细胞收缩反应的调控作用

目的探讨缺氧诱导因子-1α（HIF-1α）对缺氧所致血管平滑肌细胞（VSMC）收缩反应的调控作用及其相关机制。方法实验分为正常组、缺氧组和给药组（寡霉素,Oligomycin）。建立Transwell内皮细胞和平滑肌细胞双室联合共培养模型,分别于缺氧后不同时间点（0、0.5、1、2、3、4和6h）测定Transwell各下腔荧光渗透率以反映VSMC对去甲肾上腺素（NE）的收缩反应性;同时利用半定量逆转录-聚合酶链反应（RT-PCR）分析HIF-1α及其可能相关下游分子如内皮型一氧化氮合酶（eNOS）、诱生型一氧化氮合酶（iNOS）、环氧化酶-2（COX-2）、血红素氧化酶-1（HO-1）的mRNA表达变化规律。结果缺氧后VSMC对NE的收缩反应性变化表现为双相变化：早期代偿性增高,于0.5h达高峰,为正常组的1.53倍（P〈0.01）;至缺氧晚期则呈进行性降低,其6h收缩性较正常组降低30%（P〈0.05）。寡霉素处理可完全抑制早期反应性的升高趋势,其0.5h收缩变化为缺氧组同时间点的38.3%,但可不同程度地提高晚期反应性,其6h收缩变化较缺氧组同时间点增加12.8%（P〈0.05）。常氧状态下,联合培养内皮细胞和平滑肌细胞可稳定表达HIF-1α及其相关分子,缺氧后HIF-1αmRNA表达显著增加,于4-6h达到峰值,为正常组的1.62倍（P〈0.01）。iNOS、COX-2及HO-1的mRNA表达亦呈递增并表现为先后激活顺序、分别于2、3和4h达峰值,为正常组的3.23、2.26和2.86倍（P均〈0.01）;给药组则表现为各分子的表达维持在正常范围（P均〉0.05）。结论缺氧应激可引起VSMC对NE收缩反应性双相变化：即早期代偿性增高,晚期进行性下降;阻断HIF-1α可明显削弱该双相变化的幅度。HIF-1α可能通过对eNOS、iNOS、COX-2及HO-1的选择性作用,在缺氧后VSMC收缩反应性的双相变化中发挥重要作用。