Effect of Astragalus polysaccharides on expression of TNF-α, IL-1ß and NFATc4 in a rat model of experimental colitis.

AIM: Astragalus membranaceus is a Chinese medicinal herb and has been shown to improve hapten-induced experimental colitis. One of its major components is polysaccharides. We investigated the effect of Astragalus polysaccharides (APS) on expression of TNF-α, IL-1ß and NFATc4 in a rat model of experimental colitis. METHODS: The experimental colitis model was induced by TNBS. Forty five rats were divided into five groups (n=9): Normal control group, receiving ethanol vehicle with no TNBS during induction and IP saline injection during treatment; TNBS colitis model group (TNBS+IP saline), receiving only IP saline vehicle treatment; APS low dose group (TNBS+L-APS), receiving APS 100mg/kg; APS high dose group (TNBS+H-APS), receiving APS 200mg/kg; and positive control group (TNBS+Dexm), receiving dexamethasone 0.3mg/kg. The clinical features, macroscopic and microscopic scores were assessed. The expressions of TNF-α, IL-1ß and NFATc4 were measured by real-time PCR and ELISA assays. RESULTS: Compared to normal control rats, TNBS+IP saline had significant weight loss, increased macroscopic and microscopic scores, higher disease activity index (DAI) up-regulation of TNF-α, IL-1ß and NFATc4 mRNA expression and up-regulation of TNF-α and IL-1ß protein expression. Compared to TNBS+IP saline, treatment with APS or dexamethasone significantly reduced DAI, partially but significantly prevented TNBS colitis-induced weight loss and improved both macroscopic and microscopic scores; high dose APS or dexamethasone significantly down-regulated TNF-α and IL-1ß expressions (both mRNA and protein) and up-regulated NFATc4 mRNA and protein expression. The effect of high dose APS and dexamethasone is comparable. CONCLUSIONS: APS significantly improved experimental TNBS-induced colitis in rats through regulation of TNF-α, IL-1ß and NFATc4 expression.

The phosphodiesterase-4 inhibitor rolipram reverses Aß-induced cognitive impairment and neuroinflammatory and apoptotic responses in rats.

ß-amyloid (Aß) peptides play an important role in cognition deficits, neuroinflammation, and apoptosis observed in Alzheimer's disease (AD). Activation of cyclic AMP (cAMP) signalling enhances memory and inhibits inflammatory and apoptotic responses. However, it is not known whether inhibition of phosphodiesterase-4 (PDE4), a critical controller of intracellular cAMP concentrations, affects AD-associated neuroinflammatory and apoptotic responses and whether these responses contribute to deficits of memory mediated by cAMP signalling. We addressed these issues using memory tests and neurochemical measures. Specifically, rats microinfused with aggregated Aß25-35 (10 µg/side) into bilateral CA1 subregions displayed deficits in learning ability and memory, as evidenced by decreases in escape latency during acquisition trials and exploratory activities in the probe trial in the water-maze task and 24-h retention in the passive avoidance test. These effects were reversed by rolipram (0.1, 0.25 and 0.5 mg/kg.d i.p.), a prototypic PDE4 inhibitor, in a dose-dependent manner. Interestingly, Aß25-35-treated rats also displayed decreases in expression of phosphorylated cAMP response-element binding protein (pCREB) and Bcl-2, but increases in expression of NF-κB p65 and Bax in the hippocampus; these effects were also reversed by rolipram in a dose-dependent manner. Similar neurochemical results were observed by replacing Aß25-35 with Aß1-42, a full-length amyloid peptide that quickly forms toxic oligomers. These results suggest that PDE4 inhibitors such as rolipram may reverse Aß-induced memory deficits at least in part via the attenuation of neuronal inflammation and apoptosis mediated by cAMP/CREB signalling. PDE4 could be a target for treatment of memory loss associated with AD.

Prevention of cerebral ischemia-induced memory deficits by inhibition of phosphodiesterase-4 in rats.

Inhibition of phosphodiesterase-4 (PDE4) by rolipram, a prototypical PDE4 inhibitor, reverses memory impairment produced pharmacologically or genetically. Comparably, much less is known about the effect of rolipram on cerebral ischemia-induced memory deficits. The objective of this study was to determine the effects of rolipram on ischemia-induced memory deficit, neuronal damage, and alteration of PDE4 activity in the hippocampus. Memory was examined using Morris water-maze and step-through passive avoidance tests in rats subjected to global cerebral ischemia with or without repeated treatment with rolipram (0.3 or 1 mg/kg, i.p.); neuronal damage in the hippocampus and PDE4 activity in hippocampal tissues were determined using Nissl staining and HPLC, respectively. In the water-maze test, cerebral ischemia significantly increased the escape latency to reach the platform during acquisition training and decreased the exploration time in the target quadrant in the probe trial test; these were blocked by rolipram in a dose-dependent manner. Rolipram also reduced the distracted platform searches induced by cerebral ischemia. In the passive avoidance test, ischemia decreased the 24-h latency to the dark compartment, which was also blocked by rolipram treatment. In addition, Nissl staining revealed ischemia-induced neuron loss in hippocampal CA1; this was blocked by rolipram. Further, cerebral ischemia led to increases in activity of PDE, primarily PDE4, in the hippocampus, which also was antagonized by rolipram. These results suggest that rolipram prevents cerebral ischemia-induced memory deficits via inhibition of increased PDE4 activity and attenuation of hippocampal, neuronal damages induced by ischemia. PDE4 may be a target for treatment of cognitive disorders associated with cerebral ischemia.

Promotion of ß-amyloid production by C-reactive protein and its implications in the early pathogenesis of Alzheimer's disease.

C-reactive protein (CRP) and ß-amyloid protein (Aß) are involved in the development of Alzheimer's disease (AD). However, the relationship between CRP and Aß production is unclear. In vitro and in vivo experiments were performed to investigate the association of CRP with Aß production. Using the rat adrenal pheochromocytoma cell line (PC12 cells) to mimic neurons, cytotoxicity was evaluated by cell viability and supernatant lactate dehydrogenase (LDH) activity. The levels of amyloid precursor protein (APP), beta-site APP cleaving enzyme (BACE-1), and presenilins (PS-1 and PS-2) were investigated using real-time polymerase chain reaction and Western blotting analysis. Aß1-42 was measured by enzyme-linked immunosorbent assay. The relevance of CRP and Aß as well as potential mechanisms were studied using APP/PS1 transgenic (Tg) mice. Treatment with 0.5-4.0 µM CRP for 48 h decreased cell viability and increased LDH leakage in PC12 cells. Incubation with CRP at a sub-toxic concentration of 0.2 µM increased the mRNA levels of APP, BACE-1, PS-1, and PS-2, as well as Aß1-42 production. CRP inhibitor reversed the CRP-induced upregulations of the mRNA levels of APP, BACE-1, PS-1, and PS-2, and the protein levels of APP, BACE-1, PS-1, and Aß1-42, but did not reversed Aß1-42 cytotoxicity. The cerebral levels of CRP and Aß1-42 in APP/PS1 Tg mice were positively correlated, accompanied with the elevated mRNA expressions of serum amyloid P component (SAP), complement component 1q (C1q), and tumor necrosis factor-α (TNF-α). These results suggest that CRP cytotoxicity is associated with Aß formation and Aß-related markers expressions; CRP and Aß were relevant in early-stage AD; CRP may be an important trigger in AD pathogenesis.

[Effects of piperphentonamine hydrochloride on cognitive deficits in rats induced by cerebral ischemia-reperfusion].

OBJECTIVE: To investigate the effect of piperphentonamine hydrochloride (PPTA) on cognitive deficits induced by ischemia-reperfusion and explore the possible mechanisms. METHODS: SD rats were randomly divided into sham-operated group, ischemia-reperfusion group (with saline injection), PPTA-treated groups (2.5, 5, 10 mg/kg) and edaravone-treated group (6 mg/kg). Cerebral ischemia-reperfusion injury was induced by middle cerebral artery occlusion, and the agents were administrated 1 h after ischemia. At 24 h after ischemia, step-through passive avoidance test was carried out, and 24 h later IL-1ß, TNF-α, caspase-3 and HSP-70 mRNA expressions in the ischemic brain tissues were measured with RT-PCR. RESULTS: In the step-through passive avoidance test, the rats in the ischemia-reperfusion group showed significantly shorter latency and more error times than those in the sham group, and these behavioral changes were improved significantly by treatments with PPTA and edaravone. Cerebral ischemia-reperfusion caused significantly increased expressions of IL-1ß, TNF-α, caspase-3 and HSP-70 mRNA, and these changes were obviously reversed by PPTA, but not by edaravone. CONCLUSIONS: PPTA can reverse cognitive deficits induced by cerebral ischemia-reperfusion probably by decreasing the inflammatory responses and cell apoptosis in the brain, suggesting its potential as a new therapeutic agent for improving the cognitive function following cerebral ischemia-reperfusion.

[Protective effect of polydatin on a PC12 cell model of oxygen-glucose deprivation].

OBJECTIVE: To evaluate the protective effect of polydatin on a PC12 cell model of oxygen and glucose deprivation (OGD). METHODS: A pheochromocytoma cell injury model was induced by OGD to simulate the cerebral ischemic changes. The protective effects of polydatin were investigated in this model. RESULTS: Polydatin treatment significantly enhanced the cell viability and reduced the levels of lactate dehydrogenase, nitric oxide and the malondialdehyde of the pheochromocytoma cells as compared with the OGD group. Polydatin also increased the activity of superoxide dismutase in the cells. CONCLUSION: Polydatin offers protective effect against OGD-induced injury in pheochromocytoma cells.

Antidepressant effect of the extracts from Fructus Akebiae.

Fructus Akebiae is a common ingredient in many traditional Chinese medicine complex prescriptions for the treatment of mental disorders. Previous studies indicate that the main chemical compositions of Fructus Akebiae are triterpenoid saponins with hederagenin as their sapogenin. In the present study, we enriched hederagenin from the extracts of Fructus Akebiae with a purity of approximately 70%. Using behavioral tests sensitive to antidepressant drugs, we demonstrated that acute and sub-chronic administration of the extracts of Fructus Akebiae produced antidepressant-like effects, as evidenced by decreases in the duration of immobility in forced swim and tail suspension tests in mice and reversal of chronic unpredicted mild stress-induced inhibition of sucrose consumption in rats. In addition, the extracts decreased the levels of plasma adrenocorticotrophic hormone and serum corticosterone in rats exposed to chronic unpredicted mild stress. Both behavioral and biochemical effects of the extracts were mimicked by the proven antidepressant escitalopram. These results suggest that the extracts of Fructus Akebiae exert antidepressant activity. Administration of the extracts may be beneficial for patients with depressive disorders.

Inhibition of phosphodiesterase-4 reverses memory deficits produced by Aß25-35 or Aß1-40 peptide in rats.

RATIONALE: Cyclic AMP signaling plays an important role in memory loss associated with Alzheimer's disease (AD). However, little is known about whether inhibition of phosphodiesterase-4 (PDE4), which increases intracellular cAMP, reverses ß-amyloid peptide (Aß)-induced memory deficits. OBJECTIVE: Experiments were performed to demonstrate the effect of the PDE4 inhibitor rolipram on memory impairment produced by Aß1-40 (Aß40) or its core fragment Aß25-35. METHODS: We tested memory using Morris water-maze and passive avoidance tasks and examined expression of phosphorylated cAMP response-element binding protein (pCREB) in the hippocampus in rats treated with Aß25-35 or Aß40 into bilateral CA1 subregions, with or without rolipram administration. RESULTS: Aß25-35 (10 µg/side) increased escape latency during acquisition training and decreased swimming time and distance in the target quadrant in the water-maze probe trial; it also decreased 24-h retention in the passive avoidance paradigm. All these were reversed by chronic administration of rolipram (0.5 mg/kg). Similarly, Aß40 (4 µg/side) produced memory impairment, as demonstrated by decreased retention in passive avoidance; this was also reversed by repeated treatment with rolipram. In addition, rolipram blocked extinction of memory during the 32-day testing period in the passive avoidance test. Further, Aß40 decreased pCREB expression in the hippocampus, which was also reversed by rolipram; the changes in pCREB were highly correlated with those in memory. CONCLUSIONS: These results suggest that the PDE4 inhibitor rolipram reverses cognitive deficits associated with AD most likely via increased cAMP/CREB signaling in the hippocampus; PDE4 could be a target for drugs that improve cognition in AD.

Memory deficits and neurochemical changes induced by C-reactive protein in rats: implication in Alzheimer's disease.

RATIONALE: C-reactive protein (CRP), an acute phase protein that is released in response to inflammatory stimuli, is implicated in Alzheimer's disease (AD). However, the role of CRP in memory deficits associated with AD remains unclear. OBJECTIVE: Experiments were carried out to determine whether CRP impaired memory and altered neurochemical measures associated with AD. METHODS: The effects of intra-cerebroventricular administration of CRP or beta-amyloid peptide 25-35 (Abeta(25-35)) on memory performance were evaluated using rat Morris water-maze and step-through passive avoidance tests; the levels of inflammatory cytokines (interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor (TNF-alpha)), endogenous CRP, and markers of the endogenous production of Abeta, including amyloid precursor protein (APP), presenilins (PS-1 and PS-2), and beta-site of APP cleaving enzyme (BACE), were also determined in brain regions using real-time reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting analysis. RESULTS: Treatment with CRP (25.6 microg/rat) or Abeta(25-35) (10 microg/rat) 2 weeks ahead produced impairment of long-term memory in both animal tests. Real-time RT-PCR revealed increases in messenger RNA levels of APP, IL-1beta, IL-6, TNF-alpha, and CRP in the cerebral cortex and hippocampus and those of PS-1 and PS-2 in the cerebral cortex produced by treatment with CRP or Abeta(25-35). Immunoblotting analysis showed that while expression of APP was increased in both the cerebral cortex and the hippocampus, expression of IL-1beta, BACE, and TNF-alpha was increased only in the hippocampus. CONCLUSIONS: The results suggest that CRP contributes to memory loss and early phase of pathogenesis of AD. CRP can be a novel target for therapeutic intervention of AD.

[Effect of nattokinase on restenosis after percutaneous transluminal angioplasty of the abdominal artery in rabbits].

OBJECTIVE: To investigate the effect of nattokinase on intimal hyperplasia in rabbit abdominal artery after balloon injury and explore a novel strategy for the preventing restenosis after percutaneous transluminal angioplasty. METHODS: Fifty-six New Zealand rabbits were randomly divided into 7 groups, namely the solvent control group, model group, natto extract lavage group, refined nattokinse lavage group, intravenous refined nattokinse injection group, clopidogrel group and clopidogrel-aspirin group. Balloon injury was induced by inserting the catheter through the femoral artery into the thoracic aorta of the rabbits. The platelet counts were notad and platelet aggregation was observed, and the abdominal artery was taken for pathological analysis. The expressions of MMP-2 and -9 in the abdominal artery were detected immunohistochemically. RESULTS: There was no significant difference in the platelet counts, platelet aggregation rate or MMP-2 and -9 expression between the model group and the nattokinse-treated groups (P>0.05). The stenosis index in each nattokinse-treated group was significantly greater and the neointimal proliferation index smaller than that of the model group (P<0.01 or 0.05). CONCLUSION: Nattokinse can inhibit restenosis of rabbit abdominal artery after percutaneous transluminal angioplasty, which is independent of its actions on the platelet or MMP-2 and -9 expressions.