Novel strategies to reverse chemoresistance in colorectal cancer.

Colorectal cancer (CRC) is a common gastrointestinal malignancy with high morbidity and fatality. Chemotherapy, as traditional therapy for CRC, has exerted well antitumor effect and greatly improved the survival of CRC patients. Nevertheless, chemoresistance is one of the major problems during chemotherapy for CRC and significantly limits the efficacy of the treatment and influences the prognosis of patients. To overcome chemoresistance in CRC, many strategies are being investigated. Here, we review the common and novel measures to combat the resistance, including drug repurposing (nonsteroidal anti-inflammatory drugs, metformin, dichloroacetate, enalapril, ivermectin, bazedoxifene, melatonin, and S-adenosylmethionine), gene therapy (ribozymes, RNAi, CRISPR/Cas9, epigenetic therapy, antisense oligonucleotides, and noncoding RNAs), protein inhibitor (EFGR inhibitor, S1PR2 inhibitor, and DNA methyltransferase inhibitor), natural herbal compounds (polyphenols, terpenoids, quinones, alkaloids, and sterols), new drug delivery system (nanocarriers, liposomes, exosomes, and hydrogels), and combination therapy. These common or novel strategies for the reversal of chemoresistance promise to improve the treatment of CRC.

Interactions between Candida albicans and the resident microbiota.

Candida albicans is a prevalent, opportunistic human fungal pathogen. It usually dwells in the human body as a commensal, however, once in its pathogenic state, it causes diseases ranging from debilitating superficial to life-threatening systemic infections. The switch from harmless colonizer to virulent pathogen is, in most cases, due to perturbation of the fungus-host-microbiota interplay. In this review, we focused on the interactions between C. albicans and the host microbiota in the mouth, gut, blood, and vagina. We also highlighted important future research directions. We expect that the evaluation of these interplays will help better our understanding of the etiology of fungal infections and shed new light on the therapeutic approaches.

[Involvement of PI 3 K/Akt/mTOR Signaling in Protective Effects of Moxibustion for Premature Ovarian Failure in Rats].

OBJECTIVE: To study the protective effect of moxibustion for tripterygium-induced premature ovarian failure (POF) and its underlying mechanisms in rats. METHODS: Forty-five female SD rats were randomly divided into normal control, POF model and moxibustion groups (n＝15/group). The POF model was induced by intragastric administration of Triptolide (40 mg/kg), once daily for 6 weeks. From the 4th week after modeling, moxibustion was given at "Guanyuan" (CV 4) and bilateral "Sanyinjiao" (SP 6) for 10 min, once daily for 3 weeks. Pathological changes of ovary tissues were determined by hematoxylin-eosin (HE) staining. The serum estradiol (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), interleukin-6 (IL-6) and interleukin-1 ß (IL-1 ß) contents were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of phosphatidyl inositol 3- kinase (PI 3 K), protein kinase B (Akt) and mammalian target of rapamycin (mTOR) proteins of the ovarian tissue were detected by Western blot. RESULTS: After modeling, HE staining showed that the numbers of ovarian follicles and follicular granulocytes and corpora luteum layers were decreased, and the number of corpora atretica was increased in the model group. The content of serum E2 was markedly decreased and those of serum LH, FSH, IL-6 and IL-1 ß were markedly increased in the model group (P<0.01), and the expression levels of ovarian p-PI 3 K, p-Akt and p-mTOR were markedly increased after modeling relevant to the control group (P<0.01). Following moxibustion, the pathological damage of ovarian tissue was improved, the contents of serum LH, FSH, IL-6, IL-1 ß, and the levels of p-PI 3 K, p-Akt and p-mTOR proteins in the ovarian tissue were significantly decreased (P<0.05, P<0.01), and the content of serum E2 was markedly increased (P<0.05) in comparison with the model group. CONCLUSION: Moxibustion can improve POF in POF rats, which may be related to its actions in inhibiting PI 3 K/Akt/mTOR signaling, down-regulating serum IL-6, IL-1 ß, and regulating serum hormones.

Acute liver failure enhances oral plasma exposure of zidovudine in rats by downregulation of hepatic UGT2B7 and intestinal P-gp.

HIV infection is often associated with liver failure, which alters the pharmacokinetics of many drugs. In this study we investigated whether acute liver failure (ALF) altered the pharmacokinetics of the first-line anti-HIV agent zidovudine (AZT), a P-gp/BCRP substrate, in rats. ALF was induced in rats by injecting thioacetamide (TAA, 300 mg·kg-1·d-1, ip) for 2 days. On the second day after the last injection of TAA, the pharmacokinetics of AZT was investigated following both oral (20 mg/kg) and intravenous (10 mg/kg) administration. ALF significantly increased the plasma concentrations of AZT after both oral and intravenous doses of AZT, but without affecting the urinary excretion of AZT. AZT metabolism was studied in rat hepatic microsomes in vitro, which revealed that hepatic UGT2B7 was the main enzyme responsible for the formation of AZT O-glucuronide (GAZT); ALF markedly impaired AZT metabolism in hepatic microsomes, which was associated with the significantly decreased hepatic UGT2B7 expression. Intestinal absorption of AZT was further studied in rats via in situ single-pass intestinal perfusion. Intestinal P-gp function and intestinal integrity were assessed with rhodamine 123 and FD-70, respectively. We found that ALF significantly downregulated intestinal P-gp expression, and had a smaller effect on intestinal BCRP. Further studies showed that ALF significantly increased the intestinal absorption of both rhodamine 123 and AZT without altering intestinal integrity, thus confirming an impairment of intestinal P-gp function. In conclusion, ALF significantly increases the oral plasma exposure of AZT in rats, a result partly attributed to the impaired function and expression of hepatic UGT2B7 and intestinal P-gp.

Evaluating antithrombotic activity of HY023016 on rat hypercoagulable model.

The generation of thrombus is not considered as an isolated progression without other pathologic processes, which may also enhance procoagulant state. The purpose of this study was to assess whether HY023016, a novel dabigatran prodrug and an oral direct thrombin inhibitor, or dabigatran etexilate, another thrombin inhibitor can improve the state of whole blood hypercoagulability in vitro/vivo. By using whole blood flow cytometry we explored the effects of HY023016 and dabigatran etexilate on thrombin and ADP-induced human platelet-leukocyte aggregation generated in vitro. With the method of continuous infusion of thrombin intravenous, we successfully established a rat hypercoagulable model and evaluated the effect of HY023016 or dabigatran etexilate in vivo. HY023016 was able to inhibit thrombin- or ADP-induced platelet P-selectin or CD40L expression, leukocyte CD11b expression and formation of platelet-leukocyte aggregates in dose-dependent manner. Dabigatran etexilate was unable to affect ADP-induced platelet P-selectin or CD40L expression, leukocyte CD11b expression and formation of platelet-leukocyte aggregates. Based on rat hypercoagulable model, dabigatran etexilate could reverse thrombin-induced circulatory system hypercoagulable state in a concentration-dependent manner. Dabigatran etexilate also inhibited electrical stimulation induced formation of arterial thrombus in rat under hypercoagulable state, and extracorporal circulation-induced formation of thrombus in dose-dependent manner. Compared with dabigatran etexilate, HY023016 showed nearly equal or even better antithrombotic activity, regardless of reversing the cycle of rat hypercoagulable state or inhibiting platelet-leukocyte aggregation. In surrmary, HY023016 could effectively improve hypercoagulable state of circulatory system.

Chronic administration of caderofloxacin, a new fluoroquinolone, increases hepatic CYP2E1 expression and activity in rats.

AIM: Caderofloxacin is a new fluoroquinolone that is under phase III clinical trials in China. Here we examined the effects of caderofloxacin on rat hepatic cytochrome P450 (CYP450) isoforms as well as the potential of caderofloxacin interacting with co-administered drugs. METHODS: Male rats were treated with caderofloxacin (9 mg/kg, ig) once or twice daily for 14 consecutive days. The effects of caderofloxacin on CYP3A, 2D6, 2C19, 1A2, 2E1 and 2C9 were evaluated using a "cocktail" of 6 probes (midazolam, dextromethorphan, omeprazole, theophylline, chlorzoxazone and diclofenac) injected on d 0 (prior to caderofloxacin exposure) and d 15 (after caderofloxacin exposure). Hepatic microsomes from the caderofloxacin-treated rats were used to assess CYP2E1 activity and chlorzoxazone metabolism. The expression of CYP2E1 mRNA and protein in hepatic microsomes was analyzed with RT-PCR and Western blotting, respectively. RESULTS: Fourteen-day administration of caderofloxacin significantly increased the activity of hepatic CYP2E1, leading to enhanced metabolism of chlorzoxazone. In vitro microsomal study confirmed that CYP2E1 was a major metabolic enzyme involved in chlorzoxazone metabolism, and the 14-d administration of caderofloxacin significantly increased the activity of CYP2E1 in hepatic microsomes, resulting in increased formation of 6-hydroxychlorzoxazone. Furthermore, the 14-d administration of caderofloxacin significantly increased the expression of CYP2E1 mRNA and protein in liver microsomes, which was consistent with the pharmacokinetic results. CONCLUSION: Fourteen-day administration of caderofloxacin can induce the expression and activity of hepatic CYP2E1 in rats. When caderofloxacin is administered, a potential drug-drug interaction mediated by CYP2E1 induction should be considered.

PPARγ agonists regulate bidirectional transport of amyloid-ß across the blood-brain barrier and hippocampus plasticity in db/db mice.

BACKGROUND AND PURPOSE: There is emerging evidence suggesting that abnormal transport of amyloid-ß (Aß) across the blood-brain barrier (BBB) is involved in diabetes-associated cognitive decline. We investigated whether PPARγ agonists restore Aß transport across the BBB and hippocampal plasticity in db/db mice. EXPERIMENTAL APPROACH: Efflux and influx of Aß across the BBB were determined by stereotaxic intra-cerebral or i.a. infusion of [(125) I]-Aß1-40 respectively. Receptor for advanced glycation end products (RAGE) and low-density lipoprotein receptor-related protein 1 (LRP1), which are involved in Aß influx and efflux, PPARγ and NF-κB p65 at the BBB, as well as hippocampal Aß, caspase-3, Bax and Bcl-2 were assayed by Western blot, immunohistochemistry and RT-PCR. In vivo, hippocampal LTP was recorded, and Morris water maze and Y-maze tasks were performed. KEY RESULTS: Treatment with PPARγ agonists, rosiglitazone (0.8 mg·kg(-1) ) and pioglitazone (9.0 mg·kg(-1) ), for 6 weeks significantly increased Aß efflux and decreased Aß influx across the BBB in db/db mice. Concomitantly, they decreased hippocampal Aß1-40 and Aß1-42 , suppressed neuronal apoptosis, as indicated by decreased caspase-3 activity and increased ratio of Bcl-2/Bax, and increased hippocampal plasticity, characterized by an enhanced in vivo LTP and better performance in behavioural tests. Furthermore, the PPARγ agonists induced the expression of LRP1 gene by activation of PPARγ and suppressed RAGE gene expression by inactivation of NF-κB signalling at the BBB of db/db mice. CONCLUSIONS AND IMPLICATIONS: PPARγ agonists modify abnormal Aß transport across the BBB and this is accompanied by amelioration of ß-amyloidosis and an improvement in hippocampal plasticity in diabetic mice.

Antidiabetic drugs restore abnormal transport of amyloid-ß across the blood-brain barrier and memory impairment in db/db mice.

Previous studies have shown significant changes in amyloid-ß (Aß) transport across the blood-brain barrier (BBB) under diabetic conditions with hypoinsulinemia, which is involved in diabetes-associated cognitive impairment. Present study employed db/db mice with hyperinsulinemia to investigate changes in Aß transport across the BBB, hippocampal synaptic plasticity, and restorative effects of antidiabetic drugs. Our results showed that db/db mice exhibited similar changes in Aß transport across the BBB to that of insulin-deficient mice. Chronic treatment of db/db mice with antidiabetic drugs such as metformin, glibenclamide and insulin glargine significantly decreased Aß influx across the BBB determined by intra-arterial infusion of (125)I-Aß(1-40), and expression of the receptor for advanced glycation end products (RAGE) participating in Aß influx. Insulin glargine, but not, metformin or glibenclamide increased Aß efflux across the BBB determined by stereotaxic intra-cerebral infusion of (125)I-Aß(1-40), and expression of the low-density lipoprotein receptor related protein 1 (LRP1) participating in Aß efflux. Moreover, treatment with these drugs significantly decreased hippocampal Aß(1-40) or Aß(1-42) and inhibited neuronal apoptosis. The drugs also ameliorated memory impairment confirmed by improved performance on behavioral tasks. However, insulin glargine or glibenclamide, but not metformin, restored hippocampal synaptic plasticity characterized by enhancing in vivo long-term potentiation (LTP). Further study found that these three drugs significantly restrained NF-κB, but only insulin glargine enhanced peroxisome proliferator-activated receptor γ (PPARγ) activity at the BBB in db/db mice. Our data indicate that the antidiabetic drugs can partially restore abnormal Aß transport across the BBB and memory impairment under diabetic context.

Hippocampal PPARδ Overexpression or Activation Represses Stress-Induced Depressive Behaviors and Enhances Neurogenesis.

BACKGROUND: Emerging data have demonstrated that peroxisome proliferator-activated receptor δ (PPARδ) activation confers a potentially neuroprotective role in some neurodegenerative diseases. However, whether PPARδ is involved in depression is unknown. METHODS: In this study, PPARδ was firstly investigated in the chronic mild stress (CMS) and learned helplessness (LH) models of depression. The changes in depressive behaviors and hippocampal neurogenesis were investigated after PPARδ overexpression by microinfusion of the lentiviral vector, containing the coding sequence of mouse PPARδ (LV-PPARδ), into the bilateral dentate gyri of the hippocampus or PPARδ activation by repeated systemic administration of PPARδ agonist GW0742 (5 or 10mg/kg.d, i.p., for 21 d). RESULTS: We found that both CMS and LH resulted in a significant decrease in the PPARδ expression in the hippocampi of mice, and this change was reversed by treatment with the antidepressant fluoxetine. PPARδ overexpression and PPARδ activation each suppressed the CMS- and LH-induced depressive-like behavior and produced an antidepressive effect. In vivo or in vitro studies also showed that both overexpression and activation of PPARδ enhanced proliferation or differentiation of neural stem cells in the hippocampi of mice. CONCLUSIONS: These results suggest that hippocampal PPARδ upregulation represses stress-induced depressive behaviors, accompanied by enhancement of neurogenesis.

Pretreatment with antiasthmatic drug ibudilast ameliorates Aß 1-42-induced memory impairment and neurotoxicity in mice.

Amyloid-ß peptide (Aß) is thought to be associated with the progressive neuronal death observed in Alzheimer's disease (AD). However, effective neuroprotective approaches against Aß neurotoxicity are unavailable. Here, we investigated possible preventive effects of ibudilast, as a pharmacologic phosphodiesterase inhibitor, currently used for treatment of inflammatory diseases such as asthma, on Aß 1-42-induced neuroinflammatory, apoptotic responses and memory impairment. We found that pretreatment with ibudilast (4 or 12 mg/kg, i.p.) significantly ameliorated impaired spatial learning and memory in intracerebroventricularly (ICV) Aß 1-42-injected mice, as evidenced by decrease in escape latency during acquisition trials and increase in exploratory activities in the probe trial in Morris water maze (MWM) task, and by increase in the number of correct choices and decrease in latency to enter the shock-free compartment in Y-maze test. Further study showed that ibudilast prevented generation of pro-inflammatory cytokines such as NF-κB p65 and TNF-α as well as pro-apoptotic molecule caspase-3 activation and anti-apoptotic protein Bcl-2 downregulation in both hippocampus and cortex of ICV Aß 1-42-injected mice. Taken together, our findings suggest that ibudilast has preventive effects on Aß-induced cognitive impairment via inhibiting neuroinflammatory and apoptotic responses.

Montelukast rescues primary neurons against Aß1-42-induced toxicity through inhibiting CysLT1R-mediated NF-κB signaling.

Amyloid-ß peptide (Aß), which can invoke a cascade of inflammatory responses, is considered to play a causal role in the development and progress of Alzheimer's disease (AD). Montelukast, known as a cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, is currently used for treatment of inflammatory diseases such as asthma. We have previously reported that CysLT1R activation is involved in Aß generation. In this study, we investigated rescuing effect of CysLT1R antagonist montelukast on Aß1-42-induced neurotoxicity in primary neurons. Our data showed that Aß1-42 elicited a marked increase of CysLT1R expression in primary mouse neurons. This increment of CysLT1R expression was accompanied by increases of inflammatory factors such as NF-κB p65, tumor necrosis factor-α (TNFα) and interleukin-1ß (IL-1ß) as well as pro-apoptotic protein Caspase-3 activation and anti-apoptosis protein Bcl-2 reduction. Aß1-42-mediated increase of CysLT1R expression was associated with Aß1-42-induced cytotoxicity as measured by MTT reduction assay and lactate dehydrogenase (LDH) release assay. This observation was confirmed with treatment of montelukast, a selective CysLT1R antagonist, which had significant effect on Aß1-42-induced cytotoxicity. Moreover, blockade of CysLT1R with montelukast reversed Aß1-42-mediated increase of CysLT1R expression, and concomitant changes of the pro-inflammatory factors and the apoptosis-related proteins. The results demonstrate that montelukast rescued neurons against Aß1-42-induced neurotoxicity, neuroinflammation and apoptosis by down-regulating CysLT1R-mediated NF-κB signaling, suggesting that CysLT1R may be a potential target for AD, and its antagonist may have beneficial effects for treatment of AD.

Telmisartan treatment ameliorates memory deficits in streptozotocin-induced diabetic mice via attenuating cerebral amyloidosis.

Telmisartan, an angiotensin II type 1-receptor blocker (ARBs), has been reported to exert beneficial effects on the central nervous system (CNS). However, the effect of telmisartan on cognitive impairment associated with type 1 diabetes is not well known. Here, we examined the possibility that telmisartan could improve memory function in a type 1 diabetic mouse model, streptozotocin (STZ)-induced diabetic mice. STZ-induced diabetic mice subjected to the Morris Water Maze (MWM) task exhibited a significant decline of spatial learning and memory. Oral administration of telmisartan at two nonhypotensive doses (0.7 or 0.35 mg/kg) significantly improved memory deficits in STZ-induced diabetic mice. Telmisartan treatment markedly reduced Aß42, APP, BACE1, RAGE, and NF-κB p65 of the hippocampus and cortex, but did not beneficially affect hyperglycemia and hypoinsulinemia in the STZ-induced diabetic mice compared with untreated diabetic mice. Taken together, our findings suggest that telmisartan ameliorates memory deficits in type 1 diabetic mice, at least partly because of attenuation of amyloidosis in the brain.

Montelukast targeting the cysteinyl leukotriene receptor 1 ameliorates Aß1-42-induced memory impairment and neuroinflammatory and apoptotic responses in mice.

Montelukast, known as a cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, is currently used for treatment of inflammatory diseases such as asthma. Here, we investigated effects of montelukast on neuroinflammatory, apoptotic responses, and memory performance following intracerebral infusions of amyloid-ß (Aß). The data demonstrated that intracerebroventrical infusions of aggregated Aß1-42 (410 pmol/mouse) produced deficits in learning ability and memory, as evidenced by increase in escape latency during acquisition trials and decreases in exploratory activities in the probe trial in Morris water maze (MWM) task, and by decrease in the number of correct choices and increase in latency to enter the shock-free compartment in Y-maze test, and caused significant increases in pro-inflammatory cytokines such as NF-κB p65, TNF-α and IL-1ß as well as pro-apoptotic molecule caspase-3 activation and anti-apoptotic protein Bcl-2 downregulation in hippocampus and cortex. Interestingly, this treatment resulted in upregulation of protein or mRNA of CysLT1R in both hippocampus and cortex. Blockade of CysLT1R by repeated treatment with montelukast (1 or 2 mg/kg, ig, 4 weeks) reduced Aß1-42-induced CysLT1R expression and also suppressed Aß1-42-induced increments of NF-κB p65, TNF-α, IL-1ß and caspase-3 activation, and Bcl-2 downregulation in the hippocampus and cortex. Correspondingly, montelukast treatment significantly improved Aß1-42-induced memory impairment in mice, but had little effect on normal mice. Our results show that montelukast may ameliorate Aß1-42-induced memory impairment via inhibiting neuroinflammation and apoptosis mediated by CysLT1R signaling, suggesting that CysLT1R antagonism represents a novel treatment strategy for Alzheimer's disease.

Protective effect of pranlukast on Aß1₋42-induced cognitive deficits associated with downregulation of cysteinyl leukotriene receptor 1.

Deposition of extracellular amyloid-ß (Aß) peptide is one of the pathological hallmarks of Alzheimer's disease (AD). Accumulation of Aß is thought to associate with cognition deficits, neuroinflammation and apoptosis observed in AD. However, effective neuroprotective approaches against Aß neurotoxicity are unavailable. In the present study, we analysed the effects of pranlukast, a selective cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, on the impairment of learning and memory formation induced by Aß and the probable underlying electrophysiological and molecular mechanisms. We found that bilateral intrahippocampal injection of Aß1₋42 resulted in a significant decline of spatial learning and memory of mice in the Morris water maze (MWM) and Y-maze tests, together with a serious depression of in vivo hippocampal long-term potentiation (LTP) in the CA1 region of the mice. Importantly, this treatment caused significant increases in CysLT1R expression and subsequent NF-κB signaling, caspase-3 activation and Bcl-2 downregulation in the hippocampus or prefrontal cortex. Oral administration of pranlukast at 0.4 or 0.8 mg/kg for 4 wk significantly reversed Aß1₋42-induced impairments of cognitive function and hippocampal LTP in mice. Furthermore, pranlukast reversed Aß1₋42-induced CysLT1R upregulation, and markedly suppressed the Aß1₋42-triggered NF-κB pathway, caspase-3 activation and Bcl-2 downregulation in the hippocampus and prefrontal cortex in mice. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay confirmed its presence in the brain after oral administration of pranlukast in mice. These data disclose novel findings about the therapeutic potential of pranlukast, revealing a previously unknown therapeutic possibility to treat memory deficits associated with AD.

Fructus Gardenia Extract ameliorates oxonate-induced hyperuricemia with renal dysfunction in mice by regulating organic ion transporters and mOIT3.

The potent anti-hyperuricemia activities of Fructus Gardenia Extract (FGE) have been well reported. The aim of this study was to evaluate the uricosuric and nephro-protective effects of FGE and explore its possible mechanisms of action in oxonate-induced hyperuricemic mice. FGE was orally administered to hyperuricemic and normal mice for 1 week. Serum and urinary levels of uric acid, creatinine and blood urea nitrogen (BUN), and fractional excretion of uric acid (FEUA) were measured. The mRNA and protein levels of mouse urate transporter 1 (mURAT1), glucose transporter 9 (mGLUT9), ATP-binding cassette, subfamily G, 2 (mABCG2), organic anion transporter 1 (mOAT1), mOAT3, oncoprotein induced transcript 3 (mOIT3), organic cation/carnitine transporters in the kidney were analyzed. Simultaneously, Tamm-Horsfall glycoprotein (THP) levels in urine and kidney were detected. FGE significantly reduced serum urate levels and increased urinary urate levels and FEUA in hyperuricemic mice. It could also effectively reverse oxonate-induced alterations in renal mURAT1, mGLUT9, mOAT1 and mOIT3 expressions, as well as THP levels, resulting in the enhancement of renal uric acid excretion. Moreover, FGE decreased serum creatinine and BUN levels, and up-regulated expression of organic cation/carnitine transporters, improving renal dysfunction in this model. Furthermore, FGE decreased renal mABCG2 expressions in hyperuricemic mice, contributing to its beneficial actions. However, further investigation is needed in clinical trials of FGE and its bioactive components.

Leukotriene D4 induces cognitive impairment through enhancement of CysLT1 R-mediated amyloid-ß generation in mice.

Amyloid plaques in the extracellular parenchyma mainly consist of amyloid-ß peptides (Aß), one of the pathological hallmarks in Alzheimer's disease (AD). In the present study, we examined neuroinflammation, amyloidogenesis, and memory performance following intracerebral infusions of leukotriene D4 (LTD4) in mice. The results demonstrated that intracerebral infusions of LTD4 (1 ng/mouse) produced memory impairment as determined by Morris water maze test and Y-maze test in mice, and caused the accumulation of Aß1-40 and Aß1-42 in the hippocampus and cortex through increased activity of ß- and γ-secretases accompanied with increased expression of amyloid precursor protein (APP). LTD4 also induced expression of cysteinyl leukotriene receptor 1 (CysLT(1)R) and NF-κB p65 in the hippocampus and cortex. Pretreatment with pranlukast (1.5 ng/mouse, intracerebroventricularly), a CysLT(1)R antagonist, blocked LTD4-induced amyloidogenesis, memory deficits. Pranlukast (0.6 µM) also prevented LTD4 (20 nM)-induced amyloidogenesis in the cultured neurons in vitro. Moreover, LTD4-induced increases in CysLT(1)R and NF-κB p65 in the brain were also attenuated by pranlukast. These results suggest that LTD4 increases Aß peptide burden via activation of CysLT(1)R, which further affects APP levels and activity of ß- and γ-secretases via the NF-κB pathway. Our findings identify CysLT(1)R signaling as a novel proinflammatory and proamyloidogenic pathway, and suggest a rationale for development of therapeutics targeting the CysLT(1)R in neuroinflammatory diseases such as AD.