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Aim:Potassium 2-(1-hydroxypentyl)-benzoate (dl-PHPB) is a new drug candidate for ischemic stroke. The aim of this study was to investigate the effects of dl-PHPB on memory deficits and long-term potentiation (LTP) impairment in animal models of Alzheimer's disease.Methods:The expression of NMDA receptor subunits GluN1 and GluN2B in the hippocampus and cortex of APP/PS1 transgenic mice were detected using Western blot analysis. Memory deficits of the mice were evaluated with the passive avoidance test. LTP impairment was studied in the dentate region of Aβ1-42-injected rats and APP/PS1 transgenic mice.Results:APP/PS1 transgenic mice showed significantly lower levels of GluN1 and p-GluN2B in hippocampus, and chronic administration of dl-PHPB (100 mg·kg−1·d−1, po) reversed the downregulation of p-GluN2B, but did not change GluN1 level in the hippocampus. Furthermore, chronic administration of dl-PHPB reversed the memory deficits in APP/PS1 transgenic mice. In the dentate region of normal rats, injection of dl-PHPB (100 μmol/L, icv) did not change the basal synaptic transmission, but significantly enhanced the high-frequency stimulation (HFS)-induced LTP, which was completely prevented by pre-injection of APV (150 μmol/L, icv). Chronic administration of dl-PHPB (100 mg·kg−1·d−1, po) reversed LTP impairment in Aβ1-42-injected normal rats and APP/PS1 transgenic mice.Conclusion:Chronic administration of dl-PHPB improves learning and memory and promotes LTP in the animal models of Alzheimer's disease, possibly via increasing p-GluN2B expression in the hippocampus. [ABSTRACT FROM AUTHOR]

Aim:To investigate the reverse mode function of Na+/Ca2+ exchangers NCX1.1 and NCX1.5 expressed in CHO cells as well as their modulations by PKC and PKA.Methods:CHO-K1 cells were transfected with pcDNA3.1 (+) plasmid carrying cDNA of rat cardiac NCX1.1 and brain NCX1.5. The expression of NCX1.1 and NCX1.5 was examined using Western blot analysis. The intracellular Ca2+ level ([Ca2+]i) was measured using Ca2+ imaging. Whole-cell NCX currents were recorded using patch-clamp technique. Reverse mode NCX activity was elicited by perfusion with Na+-free medium. Ca2+ paradox was induced by Ca2+-free EBSS medium, followed by Ca2+-containing solution (1.8 or 3.8 mmol/L CaCl2).Results:The protein levels of NCX1.1 and NCX1.5 expressed in CHO cells had no significant difference. The reverse modes of NCX1.1 and NCX1.5 in CHO cells exhibited a transient increase of [Ca2+]i, which was followed by a Ca2+ level plateau at higher external Ca2+ concentrations. In contrast, the wild type CHO cells showed a steady increase of [Ca2+]i at higher external Ca2+ concentrations. The PKC activator PMA (0.3-10 μmol/L) and PKA activator 8-Br-cAMP (10-100 μmol/L) significantly enhanced the reverse mode activity of NCX1.1 and NCX1.5 in CHO cells. NCX1.1 was 2.4-fold more sensitive to PKC activation than NCX1.5, whereas the sensitivity of the two NCX isoforms to PKA activation had no difference. Both PKC- and PKA-enhanced NCX reverse mode activities in CHO cells were suppressed by NCX inhibitor KB-R7943 (30 μmol/L).Conclusion:Both NCX1.1 and NCX1.5 are functional in regulating and maintaining stable [Ca2+]i in CHO cells and differentially regulated by PKA and PKC. The two NCX isoforms might be useful drug targets for heart and brain protection. [ABSTRACT FROM AUTHOR]

Aim: To study the effects of presenilin-1 (PS-1), presenilin-2 (PS-2), and amyloid beta-protein precursor (APP695) on delayed rectifier potassium channels (IK) in the cultured rat hippocampal neurons., Methods: PS-1, PS-2, and APP695 were transfected into the cultured rat hippocampal neurons by transient transfection techniques. The IK current was observed by the whole cell patch-clamp techniques., Results: IK was increased in cultured rat hippocampal neurons, after transient transfection of PS-1, PS-2, and APP695. IK amplitudes and densities were significantly increased from (1689 +/- 412) pA, (48 +/- 18) pA/pF (mock cells, GFP alone, n=17) to (5565 +/- 1403) pA, (252 +/- 107) pA/pF (PS-1/GFP, n=22, P<0.01), (3804 +/- 1651) pA, (120 +/- 58) pA/pF (PS-2/GFP, n=16, P<0.01), and (4978 +/- 904) pA, (218 +/- 70) pA/pF (APP695, n=22, P<0.01). But PS-1, PS-2, and APP695 did not alter the activation curve of IK (P>0.05)., Conclusion: Overexpression of PS-1, PS-2, and APP695 increased IK in the cultured rat hippocampal neurons. The upregulation of IK may be related to neuronal apoptosis after PS-1, PS-2, and APP695 were transfected.

Aim: To investigate the effects of 3-n-butylphthalide (NBP) on apoptosis induced by transient focal cerebral ischemia in rats, compare the action potency of s-(-)-, r-(+)- and (+/-)-NBP, and clarify the enantiomer that played a main role., Methods: DNA fragmentation was detected by the terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) assay and gel electrophoresis. The expression of cytochrome c and caspase-3 protein was observed by Western blot analysis and immunohistochemistry. Middle cerebral artery was occluded for 2 h., Results: Significant DNA fragmentation was detected at 24 h after reperfusion. This response was inhibited by s-(-)-NBP (5, 10 mg/kg i.p.). s-(-)-NBP 10 mg/kg almost completely inhibited DNA fragmentation, whereas r-(+)- NBP 10 mg/kg showed less effect. (+/-)-NBP (20 mg/kg) showed an inhibitory effect between that of s-(-)-NBP (10 mg/kg) and r-(+)-NBP (10 mg/kg). During the apoptotic process, cytochrome c was released into the cytosol and caspase-3 was activated. This effect was markedly inhibited by s-(-)-NBP, and the action potency of r-(+)- and (+/-)-NBP on the changes of cytochrome c and caspase-3 protein was similar to that on DNA fragmentation., Conclusion: NBP, especially its s-(-)-enantiomer, could potently reduce the release of cytochrome c, decrease the activation of caspase-3, and inhibit DNA fragmentation after transient focal cerebral ischemia. Our findings on the beneficial effects of NBP on cerebral ischemia-induced apoptosis might have important implications for the study and treatment of ischemic cerebrovascular diseases.