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Li-Ping Liu,
Tian-Hua Yan,
Li-Ying Jiang,
Wei Hu,
Meng Hu,
Chao Wang,
Qian Zhang,
Yan Long,
Jiang-Qing Wang, Yong-Qi Li,
Mei Hu,
Hao Hong
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ABSTRACT: Aim:To examine the effects of pioglitazone, a PPARγ agonist, on memory performance and brain amyloidogenesis in streptozotocin (STZ)-induced diabetic mice.Methods:ICR male mice were injected with STZ (150 mg/kg, iv) to induce experimental diabetes. Pioglitazone (9 and 18 mg·kg(-1)·d(-1), po) was administered for 6 weeks. Passive avoidance and Morris water maze (MWM) tests were used to evaluate cognitive function. The blood glucose and serum insulin levels were detected using the glucose oxidase method and an ELISA assay, respectively. β-amyloid (Aβ), β-amyloid precursor protein (APP), β-amyloid precursor protein cleaving enzyme 1 (BACE1), NF-κB p65, the receptor for advanced glycation end products (RAGE) and PPARγ in the brains were analyzed using Western blotting assays.Results:The STZ-induced diabetic mice characterized by hyperglycemia and hypoinsulinemia performed poorly in both the passive avoidance and MWM tests, accompanied by increased Aβ1-40/Aβ1-42, APP, BACE1, NF-κB p65 and RAGE levels and decreased PPARγ level in the hippocampus and cortex. Chronic pioglitazone treatment significantly ameliorated the memory deficits and amyloidogenesis of STZ-induced diabetic mice, and suppressed expression of APP, BACE1, RAGE and NF-κB p65, and activated PPARγ in the hippocampus and cortex. However, pioglitazone did not significantly affect blood glucose and insulin levels.Conclusion:Pioglitazone ameliorates memory deficits in STZ-induced diabetic mice by reducing brain Aβ level via activation of PPARγ, which is independent of its effects on blood glucose and insulin levels. The results suggest that pioglitazone may be used for treating the cognitive dysfunction in type 1 diabetes mellitus.
Acta Pharmacologica Sinica 03/2013; · 1.95 Impact Factor
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ABSTRACT: Although the pathogenesis of sporadic Alzheimer's disease (AD) is not clearly understood, neuroinflammation has been known to play a role in the pathogenesis of AD. To investigate a functional link between the neuroinflammation and AD, the effect of leukotriene D4 (LTD4), an inflammatory lipid mediator, was studied on amyloid-β generation in vitro. Application of LTD4 to cell monolayers at concentrations up to 40 nM LTD4 caused increases in the Aβ releases. Concentrations ⩾ 40 nM LTD4 decreased neuronal viability. Application of 20 nM LTD4 caused a significant increase in Aβ generation, as assessed by ELISA or Western blotting, without significant cytotoxicity. At this concentration, exposure of neurons to LTD4 for 24 h produced maximal effect in the Aβ generation, and significant increases in the expressions of cysteinyl leukotriene 1 receptor (CysLT(1)R) and activity of β- orγ-secretase with complete abrogation by the selective CysLT(1)R antagonist pranlukast. Exposure of neurons to LTD4 for 1 h showed activation of NF-κB pathway, by assessing the levels of p65 or phospho-p65 in the nucleus, and either CysLT(1)R antagonist pranlukast or NF-κB inhibitor PDTC prevented the nuclear translocation of p65 and the consequent phosphorylation. PDTC also inhibited LTD4-induced elevations of β- or γ-secretase activity and Aβ generation in vitro. Overall, our data show for the first time that LTD4 causes Aβ production by enhancement of β- or γ-secretase resulting from activation of CysLT(1)R-mediated NF-κB signaling pathway. These findings provide a novel pathologic link between neuroinflammation and AD.
Neurochemistry International 01/2013; · 2.86 Impact Factor
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Su-Su Tang,
Xiao-Yun Wang,
Hao Hong,
Yan Long, Yong-Qi Li,
Li-Ying Jiang,
Han-Ting Zhang,
Li-Ping Liu,
Ming-Xing Miao,
Mei Hu,
Ting-Ting Zhang,
Wei Hu,
Hui Ji,
Feng-Ying Ye
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ABSTRACT: Amyloid plaques in the extracellular parenchyma mainly consist of Amyloid-β peptides (Aβ), 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 LTD4 produced memory impairment, formation of Aβ1-40 and Aβ1-42, increased the expression of cysteinyl leukotriene receptor 1 (CysLT(1)R) accompanied with accumulation of amyloid precursor protein (APP), significant increases in activity and expression of β-secretase (BACE), and increase of γ-secretase activity as well as activation of NF-κB in the hippocampus and cortex of mouse brains. These effects were blocked by pranlukast, a CysLT(1)R antagonist. α-secretase had no significant change in these processes. Our results indicate that LTD4 signaling via the CysLT(1)R increased Aβ peptide burden, possibly via effects on the APP levels, β- and γ-secretase activity mediated by NF-κB pathways. 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.
Neuropharmacology 09/2012; · 4.81 Impact Factor
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ABSTRACT: To examine the effects of Panax notoginseng saponins (PNS), the main active components of Panax notoginseng, on ovariectomy-induced osteoporosis in rats. A total of 72 six-month-old female rats were randomly assigned to sham-operated group and five ovariectomized (OVX) groups: OVX with distilled water (5 ml/kg/day, p.o.), OVX with graded doses of PNS (75, 150, 300 mg/kg/day, p.o.), and OVX with nilestriol (1 mg/kg/week, p.o.). Animals were sacrificed after a 13-week treatment course. Compared with the OVX group, PNS administration prevented OVX-induced decrease in bone mineral density (BMD) of lumbar vertebrae and total femur, and significantly increased bone structural biomechanical properties. Improvements of BMD and biomechanical properties were accompanied by the beneficial changes of PNS on trabecular microarchitecture in the tibial metaphysis. PNS at the highest dose significantly prevent decrease in trabecular bone volume over bone total volume, trabecular number, trabecular thickness, connectivity density, and increase in trabecular separation and structure model index in OVX rats. The bone-modulating effects of PNS may be due to the increased bone formation and decreased bone resorption, as was evidenced by the elevated level of serum alkaline phosphatase and decreased level of urinary deoxypyridinoline. PNS treatment is able to enhance BMD, bone strength, and prevent the deterioration of trabecular microarchitecture without hyperplastic effect on uterus. Therefore, PNS might be a potential alternative medicine for the prevention and treatment of postmenopausal osteoporosis.
Journal of Natural Medicines 04/2010; 64(3):336-45. · 1.39 Impact Factor
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ABSTRACT: Glutathione (GSH) depletion has been implicated in the pathogenesis of neurological diseases. During GSH depletion, cells of the blood-brain barrier are subjected to chronic oxidative stress. Using an in-vivo system, we have investigated whether glutathione depletion changed expression of P-glycoprotein at the blood-brain barrier in rats.
Diethyl maleate was intraperitoneally injected to induce GSH depletion in rats. P-glycoprotein expression at the blood-brain barrier was examined by Western blotting and RT-PCR, and its function was assessed by measuring the brain-to-plasma concentration ratios (Kp values) of rhodamine 123 (Rh123). Evans Blue dye was used as a blood-brain barrier indicator for examining the extravasation from the blood to the brain.
Four hours after treatment of rats with diethyl maleate, the brain GSH content significantly reduced. The mdr1a mRNA expression at the blood-brain barrier was upregulated, whereas no significant change in mdr1b mRNA expression was found. The P-glycoprotein level was significantly increased compared with control rats. At the same time, the Kp values of Rh123 suggested that function of P-glycoprotein was significantly enhanced at the blood-brain barrier in rats with GSH depletion induced by diethyl maleate. No significant difference of the Evans Blue dye concentration in the brain cortex was found between GSH depletion rats and control rats. Treatment of rats with N-acetylcysteine decreased P-glycoprotein upregulation induced by diethyl maleate.
The oxidative stress induced by GSH depletion played a positive role in the regulation of function and expression of P-glycoprotein at the blood-brain barrier in rats.
Journal of Pharmacy and Pharmacology 07/2009; 61(6):819-24. · 2.17 Impact Factor
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Sisi Chen,
Hao Xie,
Jing Wu,
Hao Hong,
Jianwen Jin,
Jinbo Fang,
Ji Huang,
Ying Zhou Fu,
Hui Ji, Yong Qi Li,
Yan Long,
Yuan Zheng Xia
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ABSTRACT: Clinical and animal studies have revealed significant cognitive impairment in type II diabetic subjects. However, whether there is a relationship between insulin resistance and cognitive function is poorly understood. In the present study, we used a high fat diet to induce insulin resistance (IR) in rats, insulin sensitivity index (ISI) (= FINS x FPG/22.5) to assess the extent of insulin resistance and the Morris Water Maze Task to judge cognitive function. The relationship between insulin sensitivity index and cognitive function was determined by analysing the correlation between ISI and the time rat spent in targeted quadrant, as well as between ISI and the times the rat swam across the very point where a platform was previously placed, using Pearson's method. Perfect negative correlation between ISI and cognitive function existed when ISI fell within a certain range, which indicates that insulin resistance is associated with cognitive function impairment in some cases where ISI might be an indicator.
Pharmazie 07/2009; 64(6):410-4. · 1.01 Impact Factor
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ABSTRACT: Deposition of amyloid-beta peptide (Abeta) in the brain of diabetes is poorly understood. The receptor for advanced glycation end products (RAGE) at the blood-brain barrier (BBB) is critical for regulation of Abeta homeostasis in the brain. In this studies, we used streptozotocin-induced diabetic mice to observe the expression of RAGE at the BBB by Western blot and immunocytochemical analysis, and the in vivo blood-to-brain influx transport of (125)I-Abeta(1-) (40) using the permeability surface area product (PS) and brain capillary uptake. In the diabetic mice with hyperglycemia (>16.0 mmol/L) at 6 weeks, RAGE expression at the BBB was significantly upregulated, no significant changes of RAGE levels were found at 1 and 3 weeks after diabetes induction. The data of PS and brain capillary uptake for Abeta showed significant RAGE-dependent transport of Abeta across the BBB and substantial RAGE-dependent brain capillary uptake at 6 weeks after diabetes induction. We conclude that the upregulation of RAGE at the BBB contributes to cerebral Abeta deposition in the diabetes.
Synapse 04/2009; 63(8):636-42. · 2.94 Impact Factor
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Hao Hong,
Li Ping Liu,
Jian Ming Liao,
Tong Sheng Wang,
Feng Ying Ye,
Jing Wu,
Ying Yu Wang,
Ying Wang, Yong Qi Li,
Yan Long,
Yuan Zheng Xia
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ABSTRACT: Deposition of amyloid-beta peptide (Abeta) in the diabetic brain is poorly understood. Low-density lipoprotein receptor related protein 1(LRP1) at the blood-brain barrier (BBB) is critical for regulation of Abeta homeostasis in the brain. In this study, we used streptozotocin-induced diabetic mice to observe the expression of LRP1 at the BBB by Western blot and immunocytochemical analysis, and to study in vivo brain-to-blood efflux transport of 125I-Abeta1-40 using brain clearance studies. In the diabetic mice with hyperglycemia (>16.0 mmol/l) at 6 weeks, LRP1 expression at the BBB was significantly downregulated; no significant changes of LRP1 levels were found at 1 and 3 weeks after diabetes induction. The data of brain clearance studies for Abeta showed significant decrease in LRP1-dependent transport of Abeta across the BBB at 6 weeks after diabetes induction, while no significant changes of LRP1-dependent transport of Abeta across the BBB at 1 or 3 weeks after diabetes induction were apparent. We conclude that the downregulation of LRP1 at the BBB contributes to cerebral Abeta deposition in diabetes mellitus.
Neuropharmacology 04/2009; 56(6-7):1054-9. · 4.81 Impact Factor
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ABSTRACT: Approximately 50% of hypertensive patients are postmenopausal women; therefore, any antihypertensive therapy must not adversely affect bone loss in this population. Recently, however, concern has been raised that use of angiotensin AT1 receptor antagonists may increase the tendency to develop postmenopausal osteoporosis by decreasing transforming growth factor-beta1 (TGF-beta1), which has been implicated in bone mass maintenance. In the present study, we selected telmisartan and valsartan as representatives of angiotensin AT1 receptor antagonists and used ovariectomized (OVX) rats as a model of human postmenopausal osteoporosis. After 3 months treatment with telmisartan (5 mg/kg daily) or valsartan (10 mg/kg daily), OVX rats showed no signs of adverse effects on bone mineral density of the lumbar vertebrae (L1-L5) or the total femur, nor did treatment affect serum levels of osteocalcin and osteoclast-derived tartrate-resistant acid phosphatase (TRACP-5b). Bone TGF-beta1 content remained unchanged, although treatment with telmisartan and valsartan significantly reduced serum TGF-beta1 levels (p < 0.05). In conclusion, chronic treatment with angiotensin AT1 receptor antagonists reduced serum but not bone TGF-beta1 levels and did not accelerate ovariectomy-induced bone loss in rats.
Canadian Journal of Physiology and Pharmacology 02/2009; 87(1):51-5. · 1.95 Impact Factor
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ABSTRACT: Angiotensin converting enzyme (ACE) inhibitors usually cause severe coughing and intolerance while antagonists for angiotensin AT(1) receptor do not stimulate the production of nitric oxide (NO). NO has been shown to regulate arterial hypertension and insulin resistance. Hence, new hybrids of antagonist for angiotensin AT(1) receptor and a NO donor may have potent anti-hypertensive effect and regulate glucose metabolism and insulin resistance. Herein, the effects of [6-(nitrooxymethyl)pyridin-2-yl] methyl 4'-[1-(1,7'-dimethyl-2'-propyl-1H,3'H-2,5'-bibenzo[d]imidazol-3'-yl)ethyl] biphenyl-2-carboxylate (WB1106), a novel NO-releasing derivative of telmisartan newly synthesized, on the vasocontraction, hypertension and diet-induced insulin resistance were examined in vitro using rat aortic strips and in normotensive and spontaneous hypertension rats (SHR rats). Apparently, WB1106 induced the vasorelaxation of contracted rat aortic strips in a dose- and time-dependent manner, which depended on the activity of guanylate cyclase, a characteristic of NO-related function. Furthermore, WB1106 reduced the contractile and blood pressure responses to angiotensin II, which relied on the release of telmisartan. Moreover, treatment with WB1106 significantly reduced the blood pressure with similar potency to telmitarsan and increased the contents of cGMP in SHR rats. Therefore, WB1106 possesses both the angiotensin AT(1) receptor antagonist activity of telmisartan and the NO-releasing property of a 'slow NO donor'. Importantly, in contrast to equimolar telmisartan, treatment with WB1106 significantly attenuated body weight gains and improved glucose tolerance in high-fat and carbohydrate-fed rats, reflecting a synergistic effect of NO and telmisartan. Potentially, WB1106 may be a potent anti-hypertensive drug for treatment of hypertension and diabetes-related cardiovascular diseases in the clinic.
European Journal of Pharmacology 01/2008; 577(1-3):100-8. · 2.52 Impact Factor
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ABSTRACT: The favorable metabolic effects of telmisartan are supposedly related to the changes in carbohydrate and lipid metabolism driven by peroxisome proliferators-activated receptor-gamma (PPARgamma). The fatty acid translocase CD36 is one of the PPARgamma targets that mediate these actions. We studied the metabolic effects of telmisartan in the NIH-derived strain of spontaneously hypertensive rats (SHR/NIH), which harbors a deletion mutation in CD36, in comparison to the original SHRs (SHR/Izm), which express wild-type CD36. In SHR/Izm, administration of telmisartan was associated with significantly lower serum levels of free fatty acids (42%), triglycerides (29%), glucose (11%), insulin (31%), and lower hepatic triglyceride (17%) levels, as well as larger epididymal fat pads (1.19-fold) than in SHR/NIH. Additionally, insulin-stimulated glucose incorporation into epididymal fat tissues was significantly augmented in SHR/Izm (1.33-fold) compared with SHR/NIH. In the epididymal fat pads of SHR/Izm treated with telmisartan, CD36 mRNA transcript (1.55-fold) and protein expression (1.37-fold) were also significantly enhanced. However, after 4 weeks of treatment with telmisartan, in SHR/NIH only serum free fatty acid levels were slightly reduced (20%). Overall, these results showed marked discrepancies in the metabolic actions of telmisartan in SHR/Izm and SHR/NIH and further supported the involvement of CD36 in the actions of this drug, suggesting that this pharmacogenetic interaction may be of particular importance in CD36-deficient patients.
Archiv für Experimentelle Pathologie und Pharmakologie 08/2006; 373(4):264-70. · 2.65 Impact Factor
