Effect of Serum Leptin on Weight Gain Induced by Olanzapine in Female Patients with Schizophrenia

Background

Olanzapine (OLZ) treatment is associated with a high risk of weight gain, and may cause abnormalities in glycolipid metabolism. Therefore, the underlying mechanism of OLZ-related weight gain is needed to clarify but not yet been adequately determined. In recent years, adipocytokines such as leptin, adiponectin, and tumor necrosis factor (TNF)-α, which play important roles in energy homeostasis, have been suggested as biomarkers of weight gain. Here, we determined if baseline plasma concentrations of leptin, adiponectin, and TNF-α predict weight gain following OLZ treatment.

Methods

We recruited 31 schizophrenia outpatients (12 men and 19 women, 28.8 ± 10.2 years old) that were unmedicated or on another antipsychotic monotherapy medication. Baseline body mass index (BMI) and plasma levels of leptin, adiponectin, and TNF-α were obtained. All patients started or were switched to OLZ monotherapy for a maximum of 1 year. BMI was also obtained at the endpoint.

Results

Mean BMI change following OLZ treatment was 2.1 ± 2.7 kg/m². BMI change from baseline to endpoint negatively-correlated with baseline leptin levels in female patients (r = −0.514, P = 0.024), but not male patients. Baseline adiponectin or TNF-α levels were not correlated with BMI change.

Conclusion

Baseline plasma leptin can have an effect on subsequent weight gain following OLZ treatment in female patients with schizophrenia.     

Preventing Olanzapine-Induced Weight Gain Using Betahistine: A Study in a Rat Model with Chronic Olanzapine Treatment

Olanzapine is the one of first line antipsychotic drug for schizophrenia and other serious mental illness. However, it is associated with troublesome metabolic side-effects, particularly body weight gain and obesity. The antagonistic affinity to histamine H₁ receptors (H₁R) of antipsychotic drugs has been identified as one of the main contributors to weight gain/obesity side-effects. Our previous study showed that a short term (2 weeks) combination treatment of betahistine (an H₁R agonist and H₃R antagonist) and olanzapine (O+B) reduced (−45%) body weight gain induced by olanzapine in drug-naïve rats. A key issue is that clinical patients suffering with schizophrenia, bipolar disease and other mental disorders often face chronic, even life-time, antipsychotic treatment, in which they have often had previous antipsychotic exposure. Therefore, we investigated the effects of chronic O+B co-treatment in controlling body weight in female rats with chronic and repeated exposure of olanzapine. The results showed that co-administration of olanzapine (3 mg/kg, t.i.d.) and betahistine (9.6 mg/kg, t.i.d.) significantly reduced (−51.4%) weight gain induced by olanzapine. Co-treatment of O+B also led to a decrease in feeding efficiency, liver and fat mass. Consistently, the olanzapine-only treatment increased hypothalamic H₁R protein levels, as well as hypothalamic pAMPKα, AMPKα and NPY protein levels, while reducing the hypothalamic POMC, and UCP₁ and PGC-1α protein levels in brown adipose tissue (BAT). The olanzapine induced changes in hypothalamic H₁R, pAMPKα, BAT UCP₁ and PGC-1α could be reversed by co-treatment of O+B. These results supported further clinical trials to test the effectiveness of co-treatment of O+B for controlling weight gain/obesity side-effects in schizophrenia with chronic antipsychotic treatment.     

Inhibition of Connexin 26 by the AMP-Activated Protein Kinase

Connexins provide intercellular connections that allow passage of ions and small organic molecules. They clamp the cell membrane potential and cellular ion composition to that of neighboring cells. The cell membrane potential and ion composition of an energy-depleted cell could thus be maintained despite its compromised Na⁺/K⁺ activity. By the same token, however, the breakdown of ion gradients in that cell imposes an additional challenge to the neighboring cells, which may jeopardize their survival. Thus, timely closure of connexins may be critically important for the survival of those cells. Energy depletion stimulates the AMP-activated protein kinase (AMPK), a serine/threonine kinase that senses energy depletion and stimulates several cellular mechanisms to enhance energy production and to limit energy utilization. The present study explored whether AMPK regulates connexin 26. To this end, cRNA encoding connexin 26 was injected into Xenopus oocytes with and without additional injection of wild-type AMPK (α1β1γ1), of the constitutively active ^γR70QAMPK (α1β1γ1[R70Q]) or of the inactive mutant ^αK45RAMPK (α1[K45R]β1γ1). Connexin 26 activity was determined in dual-electrode voltage-clamp experiments. Moreover, connexin 26 abundance was determined in the oocyte cell membrane by chemiluminescence and confocal microscopy. As a result, connexin 26-mediated current and connexin 26 protein abundance were significantly decreased by coexpression of ^γR70QAMPK and, to a lower extent, by wild-type AMPK but not by ^αK45RAMPK. In conclusion, AMPK is a potent regulator of connexin 26.     

AMP-Activated Protein Kinase Is Required for the Macropinocytic Internalization of Ebolavirus

Identification of host factors that are needed for Zaire Ebolavirus (EBOV) entry provides insights into the mechanism(s) of filovirus uptake, and these factors may serve as potential antiviral targets. In order to identify novel host genes and pathways involved in EBOV entry, gene array findings in the National Cancer Institute''s NCI-60 panel of human tumor cell lines were correlated with permissivity for EBOV glycoprotein (GP)-mediated entry. We found that the gene encoding the γ2 subunit of AMP-activated protein kinase (AMPK) strongly correlated with EBOV transduction in the tumor panel. The AMPK inhibitor compound C inhibited infectious EBOV replication in Vero cells and diminished EBOV GP-dependent, but not Lassa fever virus GPC-dependent, entry into a variety of cell lines in a dose-dependent manner. Compound C also prevented EBOV GP-mediated infection of primary human macrophages, a major target of filoviral replication in vivo. Consistent with a role for AMPK in filovirus entry, time-of-addition studies demonstrated that compound C abrogated infection when it was added at early time points but became progressively less effective when added later. Compound C prevented EBOV pseudovirion internalization at 37°C as cell-bound particles remained susceptible to trypsin digestion in the presence of the inhibitor but not in its absence. Mouse embryonic fibroblasts lacking the AMPKα1 and AMPKα2 catalytic subunits were significantly less permissive to EBOV GP-mediated infection than their wild-type counterparts, likely due to decreased macropinocytic uptake. In total, these findings implicate AMPK in macropinocytic events needed for EBOV GP-dependent entry and identify a novel cellular target for new filoviral antivirals.     

祛湿化瘀方通过调节AMPK活性改善高脂饮食诱导的实验性脂肪肝肝脏脂肪代谢

目的：研究祛湿化瘀方对高脂饮食诱导的大鼠脂肪肝AMPK蛋白活性及其相关脂肪代谢靶蛋白活性的影响,以探讨该方防治实验性脂肪肝的作用机制。方法：采用高脂饲料饮食诱导大鼠脂肪肝模型,造模大鼠给予高脂饮食4周后,按随机数字表随机分为模型组及祛湿化瘀方组,分别灌胃给予饮用水及中药祛湿化瘀方4周。实验8周末取材后观察：1）肝组织三酰甘油（Triglyceride,TG）、游离脂肪酸（Free Fatty Acid,FFA）含量,2）肝组织病理变化（HE染色、油红染色）,3）肝组织腺苷酸活化的蛋白激酶（AMP-Activated K inase,AMPK）及磷酸化AMPK、肝组织总蛋白及核蛋白固醇调节元件结合蛋白-1 c（Sterol Regulatory Element Binding Protein-1 c、SREBP-1 c）、肝组织总蛋白及核蛋白碳水化合物反应元件结合蛋白（Carbohydrate Response Element Binding Protein、ChREBP）含量、肝组织乙酰辅酶A羧化酶（Acety1 CoA Carboxylase,ACCa-se）及磷酸化ACC蛋白含量,4）肝组织AMPKα1、AMPKα2、SREBP-1、ACCα、SREBP-1 c及ChREBP基因表达水平。结果：1）模型组肝组织TG、FFA含量显著升高,肝组织出现明显大泡样脂肪变性;模型组肝组织AMPK蛋白磷酸化水平降低、核蛋白SREBP-1与ChREBP表达增加、ACC蛋白磷酸化水平降低蛋白活性升高。2）祛湿化瘀方组肝组织TG、FFA含量较模型组显著降低,肝组织炎症及脂肪变性程度减轻;祛湿化瘀方能显著升高肝组织AMPK、ACC蛋白磷酸化水平、降低核蛋白SREBP-1及ChREBP含量。结论：祛湿化瘀方通过调节AMPK活性及其相关靶蛋白活性改善高脂饮食诱导的大鼠脂肪肝肝脂肪代谢,这可能是该方有效防治实验性脂肪肝的重要作用机制之一。     

共济失调蛋白2结合蛋白1基因多态性与奥氮平所致体重增加的关联研究

目的:既往研究表明,共济失调蛋白2结合蛋白1(A2BP1)基因多态性可能与精神分裂症、孤独症及肥胖等复杂疾病关联,但目前尚无相关文献提示A2BP1基因多态性与抗精神病药所致体重增加的关联.本研究拟探讨A2BP1基因多态性与奥氮平治疗精神分裂症所致体重增加的关联.方法:本研究共入组350例精神分裂症患者,其中完成奥氮平(治疗剂量5～20 mg/d)治疗8周者为328例.采用阳性与阴性症状量表(PANSS)减分率评估药物疗效;分别于治疗前和治疗8周后测量并记录患者的清晨空腹体重并计算治疗前后体重增加率(％).提取患者外周血DNA,采用DNA测序基因分析方法,在328例汉族精神分裂症患者中,检测A2BP1基因4个单核苷酸多态性(SNP)位点(rs8048076,rs1478697,rs10500331,rs4786847)的基因型,并采用数量性状位点分析方法(QTL)探索A2BP1基因多态性与奥氮平治疗所致体重增加率的关联.结果:A2BP1基因rs8048076 (T=3.237;P=0.0012)及rs1478697 (T=2.956;P=0.0032)位点与奥氮平治疗精神分裂症8周后所致体重增加率关联(P＜0.05),经多重检验Bonferroni校正后仍有统计学意义;而rs10500331 (T=-0.293;P=0.769)与rs4786847(T=0.666; P=-0.505)在本样本中与奥氮平所致体重增加的关联无统计学意义(P＞0.05).结论:本研究结果提示在中国汉族人群中,A2BP1基因多态性可能与奥氮平治疗精神分裂症患者所致体重增加副反应关联,如能进一步验证及机制探索,则有望在精神科个体化治疗方面对药物所致体重增加的预测与防治提供线索依据.     

Energy-Dependent Modulation of Glucagon-Like Signaling in Drosophila via the AMP-Activated Protein Kinase

Adipokinetic hormone (AKH) is the equivalent of mammalian glucagon, as it is the primary insect hormone that causes energy mobilization. In Drosophila, current knowledge of the mechanisms regulating AKH signaling is limited. Here, we report that AMP-activated protein kinase (AMPK) is critical for normal AKH secretion during periods of metabolic challenges. Reduction of AMPK in AKH cells causes a suite of behavioral and physiological phenotypes resembling AKH cell ablations. Specifically, reduced AMPK function increases life span during starvation and delays starvation-induced hyperactivity. Neither AKH cell survival nor gene expression is significantly impacted by reduced AMPK function. AKH immunolabeling was significantly higher in animals with reduced AMPK function; this result is paralleled by genetic inhibition of synaptic release, suggesting that AMPK promotes AKH secretion. We observed reduced secretion in AKH cells bearing AMPK mutations employing a specific secretion reporter, confirming that AMPK functions in AKH secretion. Live-cell imaging of wild-type AKH neuroendocrine cells shows heightened excitability under reduced sugar levels, and this response was delayed and reduced in AMPK-deficient backgrounds. Furthermore, AMPK activation in AKH cells increases intracellular calcium levels in constant high sugar levels, suggesting that the underlying mechanism of AMPK action is modification of ionic currents. These results demonstrate that AMPK signaling is a critical feature that regulates AKH secretion, and, ultimately, metabolic homeostasis. The significance of these findings is that AMPK is important in the regulation of glucagon signaling, suggesting that the organization of metabolic networks is highly conserved and that AMPK plays a prominent role in these networks.     

The AMP-Activated Protein Kinase Is Involved in the Regulation of Ketone Body Production by Astrocytes

The possible role of the AMP-activated protein kinase (AMPK), a highly conserved stress-activated kinase, in the regulation of ketone body production by astrocytes was studied. AMPK activity in rat cortical astrocytes was three times higher than in rat cortical neurons. AMPK in astrocytes was shown to be functionally active. Thus, incubation of astrocytes with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a cell-permeable activator of AMPK, stimulated both ketogenesis from palmitate and carnitine palmitoyltransferase I. This was concomitant to a decrease of intracellular malonyl-CoA levels and an inhibition of acetyl-CoA carboxylase/fatty acid synthesis and 3-hydroxy-3-methylglutaryl-CoA reductase/cholesterol synthesis. Moreover, in microdialysis experiments AICAR was shown to stimulate brain ketogenesis markedly. The effect of chemical hypoxia on AMPK and the ketogenic pathway was studied subsequently. Incubation of astrocytes with azide led to a remarkable drop of fatty acid beta-oxidation. However, activation of AMPK during hypoxia compensated the depression of beta-oxidation, thereby sustaining ketone body production. This effect seemed to rely on the cascade hypoxia --> increase of the AMP/ATP ratio --> AMPK stimulation --> acetyl-CoA carboxylase inhibition --> decrease of malonyl-CoA concentration --> carnitine palmitoyltransferase I deinhibition --> enhanced ketogenesis. Furthermore, incubation of neurons with azide blunted lactate oxidation, but not 3-hydroxybutyrate oxidation. Results show that (a) AMPK plays an active role in the regulation of ketone body production by astrocytes, and (b) ketone bodies produced by astrocytes during hypoxia might be a substrate for neuronal oxidative metabolism.     

The Antipsychotic Olanzapine Interacts with the Gut Microbiome to Cause Weight Gain in Mouse

The second-generation antipsychotic olanzapine is effective in reducing psychotic symptoms but can cause extreme weight gain in human patients. We investigated the role of the gut microbiota in this adverse drug effect using a mouse model. First, we used germ-free C57BL/6J mice to demonstrate that gut bacteria are necessary and sufficient for weight gain caused by oral delivery of olanzapine. Second, we surveyed fecal microbiota before, during, and after treatment and found that olanzapine potentiated a shift towards an “obesogenic” bacterial profile. Finally, we demonstrated that olanzapine has antimicrobial activity in vitro against resident enteric bacterial strains. These results collectively provide strong evidence for a mechanism underlying olanzapine-induced weight gain in mouse and a hypothesis for clinical translation in human patients.     

A Pharmacological Activator of AMP-Activated Protein Kinase Protects Hypoxic Neurons in a Concentration-Dependent Manner

5′adenosine monophosphate-dependent protein kinase (AMPK) is a member of metabolite-sensing kinase family which plays an important role in intracellular energy metabolism, particularly in the hypoxic neurons process. However, the effect of AMPK activation on hypoxic neurons remains controversial. In the present study, we report that the effect of AMPK activation induced by pretreatment with 5-aminoimidazole-4-carboxamide-1-b-4-ribofuranoside (AICAR) in neurons using the hypoxic model in vitro. The level of AMPK activation, the neuronal viability, and the levels of two important cytoskeleton proteins were analyzed during the oxygen deprivation. The AMPK activation was increased with the elevation of the AICAR concentration in hypoxic neurons. Moreover, the AMPK activation induced by AICAR protected neurons against death from hypoxic deprivation and that strongly depended on the extent of the AMPK activation. The AMPK activation at specific range protects hypoxic neurons, but the protective effect of AMPK activation disappeared when the AMPK was over-activated by AICAR. The result from an AMPK inhibitor, Compound C, in hypoxic neurons further proves the neuroprotective effect of AICAR.     

Different Mechanisms of β-Adrenoceptor Down-Regulation by Chronic Imipramine and Electroconvulsive Treatment: Possible Role for Protein Kinase C

The aim of this study was to find out how protein kinase C (PKC) is involved in down-regulation of the beta-adrenoceptor in cortical slices of rats subjected to antidepressant treatments. The responses of the cyclic AMP generating system to forskolin, isoproterenol, and noradrenaline were tested in the absence and presence of a PKC activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). The antidepressive treatments applied were chronic administration of imipramine and electroconvulsive shock. The potentiating effect of the phorbol ester on cyclic AMP response to isoproterenol was retained in imipramine-treated animals and even accentuated in rats subjected to electroconvulsive treatment; the TPA effect on noradrenaline-induced cyclic AMP response was blunted in rats receiving imipramine, but augmented in those receiving electroconvulsive treatment. In imipramine-treated rats the beta-down-regulation was still evident in the presence of TPA; after electroconvulsive treatment the phorbol ester-induced potentiation was so high that no significant beta-down-regulation could be observed. No procedure affected the response to forskolin. The beta-down-regulation that develops during chronic imipramine treatment differs from that caused by chronic electroconvulsive treatment; in both cases it is not related to the direct effect on adenylate cyclase.     

Control of Glycolytic Flux by AMP-Activated Protein Kinase in Tumor Cells Adapted to Low pH

Tumor cells grow in nutrient- and oxygen-deprived microenvironments and adapt to the suboptimal growth conditions by altering their metabolic pathways. This adaptation process commonly results in a tumor phenotype that displays a high rate of aerobic glycolysis and aggressive tumor characteristics. The glucose regulatory molecule, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), is a bifunctional enzyme that is central to glycolytic flux and is downstream of the metabolic stress sensor AMP-activated protein kinase (AMPK), which has been suggested to modulate glycolysis and possibly activate isoforms of PFKFB, specifically PFKFB3 expressed in tumor cells. Our results demonstrated that long-term low pH exposure induced AMPK activation, which resulted in the up-regulation of PFKFB3 and an increase in its serine residue phosphorylation. Pharmacologic activation of AMPK resulted in an increase in PFKFB3 as well as an increase in glucose consumption, whereas in contrast, inhibition of AMPK resulted in the down-regulation of PFKFB3 and decreased glycolysis. PFKFB3 overexpression in DB-1 tumor cells induced a high rate of glycolysis and inhibited oxygen consumption, confirming its role in controlling glycolytic flux. These results show that low pH is a physiological stress that can promote a glycolytic phenotype commonly associated with tumorigenesis. The implications are that the tumor microenviroment contributes to tumor growth and treatment resistance.     

Ox-LDL和天然LDL诱导人动脉平滑肌细胞增殖中蛋白激酶A作用的初步研究

汪浩川等研究表明一定量Ｏｘ－ＬＤＬ能刺激培养人动脉ＳＭＣ细胞的增殖［１］,Ｄｅｊａｇｅｒ等采用交叉抑制实验证明兔ＳＭＣ细胞膜上有能结合Ｏｘ－ＬＤＬ的清道夫受体［２］,因此Ｏｘ－ＬＤＬ诱导培养人ＳＭＣ细胞增殖可能是Ｏｘ－ＬＤＬ作用于ＳＭＣ膜清道夫受体后...     

Glucagon-Like Peptide 1 (GLP-1) Can Reverse AMP-Activated Protein Kinase (AMPK) and S6 Kinase (P70S6K) Activities Induced by Fluctuations in Glucose Levels in Hypothalamic Areas Involved in Feeding Behaviour

The anorexigenic peptide, glucagon-like peptide-1 (GLP-1), reduces glucose metabolism in the human hypothalamus and brain stem. The brain activity of metabolic sensors such as AMP-activated protein kinase (AMPK) responds to changes in glucose levels. The mammalian target of rapamycin (mTOR) and its downstream target, p70S6 kinase (p70S6K), integrate nutrient and hormonal signals. The hypothalamic mTOR/p70S6K pathway has been implicated in the control of feeding and the regulation of energy balances. Therefore, we investigated the coordinated effects of glucose and GLP-1 on the expression and activity of AMPK and p70S6K in the areas involved in the control of feeding. The effect of GLP-1 on the expression and activities of AMPK and p70S6K was studied in hypothalamic slice explants exposed to low- and high-glucose concentrations by quantitative real-time RT-PCR and by the quantification of active-phosphorylated protein levels by immunoblot. In vivo, the effects of exendin-4 on hypothalamic AMPK and p70S6K activation were analysed in male obese Zucker and lean controls 1 h after exendin-4 injection to rats fasted for 48 h or after re-feeding for 2–4 h. High-glucose levels decreased the expression of Ampk in the lateral hypothalamus and treatment with GLP-1 reversed this effect. GLP-1 treatment inhibited the activities of AMPK and p70S6K when the activation of these protein kinases was maximum in both the ventromedial and lateral hypothalamic areas. Furthermore, in vivo s.c. administration of exendin-4 modulated AMPK and p70S6K activities in those areas, in both fasted and re-fed obese Zucker and lean control rats.     

Opposing Activity Changes in AMP Deaminase and AMP-Activated Protein Kinase in the Hibernating Ground Squirrel

Hibernating animals develop fatty liver when active in summertime and undergo a switch to a fat oxidation state in the winter. We hypothesized that this switch might be determined by AMP and the dominance of opposing effects: metabolism through AMP deaminase (AMPD2) (summer) and activation of AMP-activated protein kinase (AMPK) (winter). Liver samples were obtained from 13-lined ground squirrels at different times during the year, including summer and multiples stages of winter hibernation, and fat synthesis and β-fatty acid oxidation were evaluated. Changes in fat metabolism were correlated with changes in AMPD2 activity and intrahepatic uric acid (downstream product of AMPD2), as well as changes in AMPK and intrahepatic β-hydroxybutyrate (a marker of fat oxidation). Hepatic fat accumulation occurred during the summer with relatively increased enzymes associated with fat synthesis (FAS, ACL and ACC) and decreased enoyl CoA hydratase (ECH1) and carnitine palmitoyltransferase 1A (CPT1A), rate limiting enzymes of fat oxidation. In summer, AMPD2 activity and intrahepatic uric acid levels were high and hepatic AMPK activity was low. In contrast, the active phosphorylated form of AMPK and β-hydroxybutyrate both increased during winter hibernation. Therefore, changes in AMPD2 and AMPK activity were paralleled with changes in fat synthesis and fat oxidation rates during the summer-winter cycle. These data illuminate the opposing forces of metabolism of AMP by AMPD2 and its availability to activate AMPK as a switch that governs fat metabolism in the liver of hibernating ground squirrel.     

AMP-Activated Protein Kinase Suppresses the In Vitro and In Vivo Proliferation of Hepatocellular Carcinoma

AMP-activated protein kinase (AMPK) is a central metabolic sensor and plays an important role in regulating glucose, lipid and cholesterol metabolism. Therefore, AMPK is a key therapeutic target in diabetes. Recent pilot studies have suggested that diabetes drugs may reduce the risk of cancer by affecting the AMPK pathway. However, the association between AMPK and the proliferation of hepatocellular carcinoma (HCC) is unknown. In this study, we investigated the relationship between AMPK activity and the proliferation of HCC in cell lines, nude mice and human clinic samples. We first investigated the relationship between AMPK activity and cell proliferation in two HCC cell lines, PLC/PRF/5 and HepG2, by two AMPK activators, 5-aminoimidazole-4-carboxamide-1-h-D-ribofuranoside (AICAR) and metformain. AICAR and metformin treatment significantly inhibited the proliferation of HCC cells and induced cell cycle arrest at G1-S checkpoint. We then observed that metformin abrogated the growth of HCC xenografts in nude mice. The clinical pathology of AMPK activity in HCC, including cell proliferation, differential grade, tumor size and microvessel density, was studied by using 30 clinical tissue samples. In HCC tissue samples, phosphorylated AMPK was expressed mainly in cytoplasm. AMPK activity decreased significantly in HCC in comparison with paracancerous liver tissues (P<0.05). AMPK activity was negatively correlated with the level of Ki-67 (a marker of cell proliferation), differential degradation and tumor size (P<0.05), but not with microvessel density, hemorrhage or necrosis in HCC. Our findings suggest that AMPK activity inhibits the proliferation of HCC and AMPK might be an effective target for prevention and treatment of HCC.     

Activation of AMP-Activated Protein Kinase by Adenine Alleviates TNF-Alpha-Induced Inflammation in Human Umbilical Vein Endothelial Cells

The AMP-activated protein kinase (AMPK) signaling system plays a key role in cellular stress by repressing the inflammatory responses induced by the nuclear factor-kappa B (NF-κB) system. Previous studies suggest that the anti-inflammatory role of AMPK involves activation by adenine, but the mechanism that allows adenine to produce these effects has not yet been elucidated. In human umbilical vein endothelial cells (HUVECs), adenine was observed to induce the phosphorylation of AMPK in both a time- and dose-dependent manner as well as its downstream target acetyl Co-A carboxylase (ACC). Adenine also attenuated NF-κB targeting of gene expression in a dose-dependent manner and decreased monocyte adhesion to HUVECs following tumor necrosis factor (TNF-α) treatment. The short hairpin RNA (shRNA) against AMPK α1 in HUVECs attenuated the adenine-induced inhibition of NF-κB activation in response to TNF-α, thereby suggesting that the anti-inflammatory role of adenine is mediated by AMPK. Following the knockdown of adenosyl phosphoribosyl transferase (APRT) in HUVECs, adenine supplementation failed to induce the phosphorylation of AMPK and ACC. Similarly, the expression of a shRNA against APRT nullified the anti-inflammatory effects of adenine in HUVECs. These results suggested that the role of adenine as an AMPK activator is related to catabolism by APRT, which increases the cellular AMP levels to activate AMPK.