Prevention of resveratrol on spatial memory loss of mice induced by calyculin A / 中国病理生理杂志

AIM:To explore the preventive effect of resveratrol on spatial memory loss of the mice induced by intralateroventricular injection of calyculin A (CA).METHODS:Kunming mice of 2 months (n=44) were divided into saline control group, CA group, low-dose resveratrol group and high-dose resveratrol group.The mice in control group and CA group were intraperitoneally injected with equal volume of saline for 21 d, while the mice in low-dose resveratrol group and high-dose resveratrol group were intraperitoneally injected with resveratrol at 5 mg/kg and 10 mg/kg, respectively.At 22 d, CA (4 μL) was injected into the lateral ventricles in CA group, low-dose resveratrol group and high-dose resveratrol group.Morris water maze test was applied to examine the changes of learning and memory abilities of the mice at 27 d.The Golgi staining was used to observe the morphological changes of dendrites and dendritic spines.The hippocampal tissues were homogenated to detect SOD activity.RESULTS:Low-dose resveratrol significantly decreased the escape latency delay induced by CA.Low-dose resveratrol attenuated the decreases in the number of dendrites and the density of dendritic spines of neurons in hippocampal CA1 region induced by CA.High-dose resveratrol but not low-dose resveratrol attenuated the decreased SOD activity induced by CA.CONCLUSION:Resveratrol at low dose attenuates memory loss in the mice induced by CA though preventing dendrite injury.

lnhibiton of JNK phosphorylation involved in melatonin′s protection of calyculin A-induced tau hyperphosphorylation / 中国药理学与毒理学杂志

OBJECTlVE To explore the mechanisms of tau hyperphosphorylation induced by calyculin A ( CA) in neuroblastoma cells and the effect of melatonin. METHODS N2a cells were treated with CA 5 nmol·L-1 , or CA with melatonin 50 μmol·L-1 , or CA with vitamin E ( Vit E ) 50 μmol·L-1 for 12 h. The level of tau phosphorylation at Ser422 ( recognized by R145d antibody) site and the level of phosphorylated c-Jun N-terminal kinases ( p-JNK ) and phosphorylated mitogen-activated protein kinase kinase 4 ( p-MKK4 ) were detected with immunoblotting, the level of malondialdehyde ( MDA ) was assayed with fluorimetry, and the activity of p38-mitogen activated protein kinase ( p38MAPK ) was assayed by radioimmunobloting. RESULTS CA treatment increased the level of phosphorylated tau at Ser422 site (1.70±0.19, 1.0, P<0.01), and melatonin attenuated the effect of CA (0.98±0.12, 1.70± 0.19, P<0.01). ln addition, CA treatment increased the level of MDA (μmol·g-1 protein:0.241±0.006, 0.141±0.006, P<0.01) and melatonin antagonized the increase of MDA induced by CA (μmol·g-1 protein:0.172±0.004, 0.193±0.005, 0.241±0.006, P<0.01) . CA treatment increased the level of p-JNK (1.91±0.27, 1, P<0.01) and p-MKK4 (1.81±0.09, 1, P<0.01) and melatonin antagonized the effect of CA induced increase of p-JNK (1.11±0.15, 1.91±0.27, P<0.01) and p-MKK4 (1.14±0.06, 1.81±0.09, P<0.01) without changing the level or activity of p38MAPK. Both JNK inhibitor ( SP600125 ) and MKK4/JNK transduction pathway inhibitor antagonized CA induced tau phosphorylation at Ser422 site and JNK phosphorylation. CONCLUSlON lnhibiton of JNK phosphorylation is possibly involved in the protection of melatonin on CA-induced tau hyperphosphorylation at Ser422 site.

Calyculin A modulates activation of the NADPH-oxidase in Me2SO-differentiated HL-60 cells

Human promyelocytic leukemia cells (HL-60) have been used as a model system in which to study the effects of protein phosphatase inhibitors on NADPH-oxidase activation. Since O2- is generated by NADPH-oxidase, we examined the effect of calyculin A pretreatment on oxidase activation in response to various agonists. When Me2SO-differentiated HL-60 cells were treated with calyculin A prior to the addition of phorbol 12-myristate 13-acetate (PMA), O2- production was inhibited; however, calyculin A enhanced O2- production by N-formyl-methionyl-leucyl-phenylalanine (FMLP). The decreased O2- production seen with calyculin A pretreatment followed by PMA may be due to diminished translocation of the p47-phox and p67-phox, cytosolic components of the oxidase, and inhibition of arachidonic acid release. Interestingly calyculin A pretreatment followed by either agonist significantly enhanced mitogen-activated-protein kinase (MAPK) activity. The differential effects of pretreatment with calyculin A on subsequent oxidase stimulation elicited by FMLP or PMA provide further evidence for substantial heterogeneity in the activation of the respiratory burst.

Effect of melatonin on calyculin A-induced tau hyperphosphorylation / 西安交通大学学报(医学版)

Objective To investigate the in vivo effect of melatonin(Mel) on calyculin A(CA)-induced tau hyperphosphorylation in neuroblastoma cells(N2awt).Methods We treated N2awt cells with CA or CA and 50 ?mol/L Mel,detected the level of tau phosphorylation with immunofluorescence,and assayed the activities of GSK3 and the ratio of GSK-3? phosphorylated at Ser9 site to total GSK-3?.Results CA treatment led to tau hyperphosphorylation accompanied with the increased activity of GSK-3 and the decreased ratio of GSK-3? phosphorylated at Ser9 site to total GSK-3?.When the cells were incubated simultaneously with CA and 50 ?mol/L Mel,the CA-induced tau hyperphosphorylation,GSK-3 activation and the ratio of GSK-3? phosphorylated at Ser9 site to total GSK-3? decrease were attenuated.Conclusion Melatonin protects neuroblastoma cells from CA-induced tau hyperphosphorylation.Its protection may be related to the regulation of GSK-3 activity and the ratio of GSK-3? phosphorylated at Ser9 site to total GSK-3? increase.

Effect of melatonin on calyculin A-induced neurofilament hyperphosphorylation / 西安交通大学学报(医学版)

Objective To investigate the in vivo effect of melatonin on calyculin A-induced neurofilament(NF) hyperphosphorylation in neuroblastma cells(N2awt).Methods N2awt cells were treated with CA or CA and different concentration melatonin or CA and vitamin E,the levels of neurofilament phosphorylation and the level of PP-2A were detected,and the activities of PP-2A were assayed.Results Calyculin A treatment led to neurofilament hyperphosphorylation by decreasing the level and activity of PP-2A.Both melatonin and vitamin E had protective effect on calyculin A-induced neurofilament hyperphosphorylation,although melatonin increased the activity of PP-2A while vitamin E did not.Morever,melatonin partially attenuated the decreasing of PP-2A level. Conclusion Melatonin protects neuroblastma cells from CA-induced neurofilament hyperphosphorylation through the regulation of PP-2A level and the increase of PP-2A activity.