Lithium inhibits NF-κB nuclear translocation and modulate ...
P3-351: Cyclooxygenase-derived prostanoids modulate α-secretase activity
1
P3-349 COGNITIVE TRAINING INCREASES PLATELET PLA 2 ACTIVITY IN HEALTHY ELDERLY SUBJECTS Leda L. Talib, Monica S. Yassuda, Breno S. O. Diniz, Orestes V. Forlenza, Wagner F. Gattaz, Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil. Contact e-mail: [email protected] Background: Phospholipases A 2 (PLA 2 ) are ubiquitous enzymes involved in membrane fatty acid metabolism and intracellular signalling. Recent studies have shown that PLA 2 subtypes are implicated in the modulation of pathways related to memory acquisition and retrieval. Methods: We in- cluded 23 cognitively unimpaired older individuals were selected to this study divided in the experimental and control groups (EG and CG, respec- tively). The EG underwent a four-session memory training intervention and the CG completed the same evaluation as EG and received standard outpatient care only. Pre and pos-test measures included prose and list recall, WAIS-III digit symbol, strategy use measures, and PLA 2 group activity. The PLA 2 group activity was determined by radio-enzymatic assay. Results: After cognitive training, patients in the EG group had significant increase in cPLA 2 , sPLA 2 , total PLA 2 activity, and significant decrease in iPLA 2 activity (see table). Conclusions: Our results suggest that memory training may have a modulating effect on biological systems associated with cognitive functions and neurodegenerative diseases. P3-350 OVERACTIVATION OF GLYCOGEN SYNTHASE KINASE-3 BY INHIBITION OF PHOSPHOINOSITOL-3 KINASE AND PROTEIN KINASE C DECREASES ACh LEVEL IN NUCLEUS BASALIS OF MEYNERT AND FRONTAL CORTEX THROUGH DIFFERENT MECHANISMS IN RATS Yue Wang 1,2 , Li Zhao 1 , Qing Tian 1,2 , Xia Jiang 1 , Juan Zeng 1 , Jian-zhi Wang 1,2 , 1 Department of Pathophysiology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China; 2 Hubei Provincial Key Laboratory of Neurological Diseases, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD), the most common type of de- mentia in the elderly, is characterized by intracellular neurofibrillary tan- gles, cholinergic dysfunction and memory deficit. It has been reported that glycogen synthase kinase-3 (GSK-3) is the key kinase among protein kinases which can phosphorylate tau in the AD brain. We activated GSK-3 and induced a series of AD-like pathological alterations in rats by ventric- ular injection of Wortmannin (WT, PI3-K inhibitor) and GF-109203X (GFX, PKC inhibitor) at 24h-48h. It has been developed that GSK-3 may affect cholinergic function and inhibit protein expression, so we explored the relationship between GSK-3 activation and cholinergic function and underlying mechanisms.Methods: We used lateral ventricular injection of WT plus GFX to activate cerebral GSK-3 in rats. Then we detected acetylcholine (ACh) level by microdialysis and high performance liquid chromatography. Expression of relative protein level was detected by western blotting. Transcription level of choline acetyltransferase (ChAT) was detected by reverse transcription polymerase chain reaction. Distribu- tion of relative protein level was detected by immunohistochemistry, dou- ble-labeling immunofluorescence and Bielschowsky’s silver staining. Nissl staining was used for neuronal identification. Results: Ventricular injection of WT and GFX decreased ACh levels in nucleus basalis of Meynert (NBM) and frontal cortex at 24h-72h and the phosphorylation level of GSK-3 at Ser9 at 24h-48h. Ventricular injection of WT and GFX decreased ChAT expression and induced transport deficit of ChAT in NBM, but only induced transport deficit of ChAT in frontal cortex. Decreased ChAT expression in NBM is due to the inhibition of its transcription by NF- B/ p52 in nucleus. Conclusions: GSK-3 overactivation can result in decreased ACh level in NBM and frontal cortex. The decreased ACh level in NBM is due to reduced ChAT expression and transport deficit. But the decreased ACh level in frontal cortex is only due to ChAT transport deficit. Addi- tionally, we found GSK-3 overactivation can inhibit ChAT expression through NF- B/p52 signal pathway activation. The ACh regulation by GSK-3 can act as the interpretation of GSK-3 induced spatial memory deficit in rats. The results supply more proof that GSK-3 can act as a good therapy target in Alzheimer’s disease. P3-351 CYCLOOXYGENASE-DERIVED PROSTANOIDS MODULATE -SECRETASE ACTIVITY Valery N. Yermalitsky, John A. Oates, Olivier Boutaud, Vanderbilt University, Nashville, TN, USA. Contact e-mail: [email protected] Background: The amyloid precursor protein (APP) is processed by two exclusive proteolytic pathways that are initiated by the - and the -secre- tases. Down regulation of the -secretase activity is associated with in- creased levels of -secretase products in brain, including amyloid , and decreased levels of sAPP, the product of -secretase. Such decrease of protease activity is associated with aging in humans and with oxidative stress. Methods: Using human platelets we have obtained evidence that sAPP release is highly regulated by the interplay of several prostaglandin receptors. Results: Secretion of sAPP has been analyzed in human platelets in response to various agonists. Activation of the thromboxane (TP) receptor with a specific agonist U46,619 gave the same response as arachidonic acid (AA), suggesting that the effect of the fatty acid was mediated by thromboxane A2. The maximal effect was obtained with 500 nM of TP receptor agonist or 7.5 M of AA. We showed that the effect of AA was antagonized by SQ29,548, a specific antagonist of the TP receptor, in a dose-dependent manner, confirming that this effect of AA was medi- ated through the TP receptor. We obtained results indicating that carba- prostacyclin (CP), a stable analog of prostacyclin, antagonized in a dose- dependent manner the effect of U46,619. We found that at low nanomolar concentrations, PGE2 potentiates the effect of a sub-efficacious concen- tration of AA on sAPP release from human platelet. We observed that when platelets were activated simultaneously with both U46,619 and AA, the secretion of sAPP was inhibited by AA in a dose-dependent manner. We have shown previously that oxidation of AA by prostaglandin H2 synthase-1 in human platelet leads to formation of very reactive -ketoal- dehydes, levuglandins and that they form covalent adducts with lysine residues. Accordingly, we showed that levuglandin prevents cleavage of a fluorescent substrate of -secretase by purified ADAM10. Conclusions: These results indicate that prostanoid receptors can either stimulate or inhibit -secretase activity and that modification of the APP by levuglan- dins could prevent its cleavage by -secretase. This evidence provides support for a new paradigm for the participation of cyclooxygenases in the development of Alzheimer’s disease. T624 Poster Presentations P3:
Transcript of P3-351: Cyclooxygenase-derived prostanoids modulate α-secretase activity
P3-349 COGNITIVE TRAINING INCREASES PLATELETPLA2 ACTIVITY IN HEALTHY ELDERLYSUBJECTS
Leda L. Talib, Monica S. Yassuda, Breno S. O. Diniz,Orestes V. Forlenza, Wagner F. Gattaz, Institute of Psychiatry, Facultyof Medicine, University of Sao Paulo, Sao Paulo, Brazil. Contacte-mail: [email protected]
Background: Phospholipases A2 (PLA2) are ubiquitous enzymes involvedin membrane fatty acid metabolism and intracellular signalling. Recentstudies have shown that PLA2 subtypes are implicated in the modulation ofpathways related to memory acquisition and retrieval. Methods: We in-cluded 23 cognitively unimpaired older individuals were selected to thisstudy divided in the experimental and control groups (EG and CG, respec-tively). The EG underwent a four-session memory training intervention andthe CG completed the same evaluation as EG and received standardoutpatient care only. Pre and pos-test measures included prose and listrecall, WAIS-III digit symbol, strategy use measures, and PLA2 groupactivity. The PLA2 group activity was determined by radio-enzymaticassay. Results: After cognitive training, patients in the EG group hadsignificant increase in cPLA2, sPLA2, total PLA2 activity, and significantdecrease in iPLA2 activity (see table). Conclusions: Our results suggestthat memory training may have a modulating effect on biological systemsassociated with cognitive functions and neurodegenerative diseases.
P3-350 OVERACTIVATION OF GLYCOGEN SYNTHASEKINASE-3 BY INHIBITION OFPHOSPHOINOSITOL-3 KINASE AND PROTEINKINASE C DECREASES ACh LEVEL IN NUCLEUSBASALIS OF MEYNERT AND FRONTAL CORTEXTHROUGH DIFFERENT MECHANISMS IN RATS
Yue Wang1,2, Li Zhao1, Qing Tian1,2, Xia Jiang1, Juan Zeng1, Jian-zhiWang1,2, 1Department of Pathophysiology, Tongji Medical College ofHuazhong University of Science and Technology, Wuhan, China; 2HubeiProvincial Key Laboratory of Neurological Diseases, Tongji MedicalCollege, Huazhong University of Science and Technology, Wuhan,China. Contact e-mail: [email protected]
Background: Alzheimer’s disease (AD), the most common type of de-mentia in the elderly, is characterized by intracellular neurofibrillary tan-gles, cholinergic dysfunction and memory deficit. It has been reported thatglycogen synthase kinase-3 (GSK-3) is the key kinase among proteinkinases which can phosphorylate tau in the AD brain. We activated GSK-3and induced a series of AD-like pathological alterations in rats by ventric-ular injection of Wortmannin (WT, PI3-K inhibitor) and GF-109203X(GFX, PKC inhibitor) at 24h-48h. It has been developed that GSK-3 may
affect cholinergic function and inhibit protein expression, so we exploredthe relationship between GSK-3 activation and cholinergic function andunderlying mechanisms. Methods: We used lateral ventricular injection ofWT plus GFX to activate cerebral GSK-3 in rats. Then we detectedacetylcholine (ACh) level by microdialysis and high performance liquidchromatography. Expression of relative protein level was detected bywestern blotting. Transcription level of choline acetyltransferase (ChAT)was detected by reverse transcription polymerase chain reaction. Distribu-tion of relative protein level was detected by immunohistochemistry, dou-ble-labeling immunofluorescence and Bielschowsky’s silver staining. Nisslstaining was used for neuronal identification. Results: Ventricular injectionof WT and GFX decreased ACh levels in nucleus basalis of Meynert(NBM) and frontal cortex at 24h-72h and the phosphorylation level ofGSK-3 at Ser9 at 24h-48h. Ventricular injection of WT and GFX decreasedChAT expression and induced transport deficit of ChAT in NBM, but onlyinduced transport deficit of ChAT in frontal cortex. Decreased ChATexpression in NBM is due to the inhibition of its transcription by NF-B/p52 in nucleus. Conclusions: GSK-3 overactivation can result in decreasedACh level in NBM and frontal cortex. The decreased ACh level in NBMis due to reduced ChAT expression and transport deficit. But the decreasedACh level in frontal cortex is only due to ChAT transport deficit. Addi-tionally, we found GSK-3 overactivation can inhibit ChAT expressionthrough NF-B/p52 signal pathway activation. The ACh regulation byGSK-3 can act as the interpretation of GSK-3 induced spatial memorydeficit in rats. The results supply more proof that GSK-3 can act as a goodtherapy target in Alzheimer’s disease.
P3-351 CYCLOOXYGENASE-DERIVED PROSTANOIDSMODULATE �-SECRETASE ACTIVITY
Valery N. Yermalitsky, John A. Oates, Olivier Boutaud, VanderbiltUniversity, Nashville, TN, USA. Contact e-mail:[email protected]
Background: The amyloid precursor protein (APP) is processed by twoexclusive proteolytic pathways that are initiated by the �- and the �-secre-tases. Down regulation of the �-secretase activity is associated with in-creased levels of �-secretase products in brain, including amyloid �, anddecreased levels of sAPP�, the product of �-secretase. Such decrease ofprotease activity is associated with aging in humans and with oxidativestress. Methods: Using human platelets we have obtained evidence thatsAPP� release is highly regulated by the interplay of several prostaglandinreceptors. Results: Secretion of sAPP� has been analyzed in humanplatelets in response to various agonists. Activation of the thromboxane(TP) receptor with a specific agonist U46,619 gave the same response asarachidonic acid (AA), suggesting that the effect of the fatty acid wasmediated by thromboxane A2. The maximal effect was obtained with 500nM of TP receptor agonist or 7.5 �M of AA. We showed that the effect ofAA was antagonized by SQ29,548, a specific antagonist of the TP receptor,in a dose-dependent manner, confirming that this effect of AA was medi-ated through the TP receptor. We obtained results indicating that carba-prostacyclin (CP), a stable analog of prostacyclin, antagonized in a dose-dependent manner the effect of U46,619. We found that at low nanomolarconcentrations, PGE2 potentiates the effect of a sub-efficacious concen-tration of AA on sAPP� release from human platelet. We observed thatwhen platelets were activated simultaneously with both U46,619 and AA,the secretion of sAPP� was inhibited by AA in a dose-dependent manner.We have shown previously that oxidation of AA by prostaglandin H2synthase-1 in human platelet leads to formation of very reactive �-ketoal-dehydes, levuglandins and that they form covalent adducts with lysineresidues. Accordingly, we showed that levuglandin prevents cleavage of afluorescent substrate of �-secretase by purified ADAM10. Conclusions:These results indicate that prostanoid receptors can either stimulate orinhibit �-secretase activity and that modification of the APP by levuglan-dins could prevent its cleavage by �-secretase. This evidence providessupport for a new paradigm for the participation of cyclooxygenases in thedevelopment of Alzheimer’s disease.
T624 Poster Presentations P3:
