Effect of pitavastatin against expression of S100beta protein in the gerbil hippocampus after transient cerebral ischaemia

Neuroprotective effects of a traditional herbal prescription on transient cerebral global ischemia in gerbils

AIM OF THE STUDY

Kyung-Ok-Ko (KOK), a traditional herbal prescription composed of Rehmannia glutinosa var. purpurae, Panax ginseng, Poria cocos, Lycium chinense, Aquillaria agallocha and honey, has been used to treat age-related symptoms, such as amnesia or dementia, and has been shown to ameliorate scopolamine-induced memory impairment in mice. However, the effects of KOK on transient cerebral global ischemia-induced brain damage are unclear.

MATERIALS AND METHODS

Transient cerebral global ischemia was induced by occluding the bilateral common carotid artery for 5 min followed by reperfusion for 7 days. KOK (0.25, 0.5, 1, or 2 g/kg) was administered orally immediately after reperfusion and once a day over the next 7 days. Y-maze or novel object recognition tasks were to analyze learning and memory capabilities at 4 or 5 days after reperfusion, respectively. Histochemistry and immunohistochemistry were used for evaluation of the effect of KOK on neuronal degeneration.

RESULTS

Histochemical studies showed that KOK increased the number of viable cells detected by Nissl staining and decreased the number of degenerated neuronal cells detected by Fluoro-Jade B staining in the hippocampal CA1 region. In the immunohistochemical study, the sub-chronic KOK administration attenuated the ischemia-induced activation of microglia and astrocytes and the increase of cytokine IL-1β (P<0.05). In addition, KOK administration significantly attenuated the ischemia-induced cognitive impairments observed in the Y-maze and novel object recognition tasks (P<0.05).

CONCLUSION

These findings suggest that the neuroprotective effects of KOK may be mediated by its anti-inflammatory activities, resulting in the attenuation of memory impairment.

Tei index for prenatal diagnosis of acute fetal hypoxia due to intermittent umbilical cord occlusion in an animal model

OBJECTIVE

To study the effectiveness of the pulsatility index for veins of ductus venosus (DV-PIV) and the Tei index in a prospective assessment of fetal hypoxic-ischemic brain damage in a near-term ovine fetus model with intermittent umbilical cord occlusion (UCO).

METHODS

Twelve fetal sheep were studied with umbilical cord occlusion performed in the experimental group animals by complete inflation of an occluder cuff for 90 s, every 30 min for approximately 2.5 h. Fetal arterial blood was sampled at 5 min before the first umbilical cord occlusions, approximately 60 s of the first umbilical cord occlusions, and 3 min after each occlusion for blood gas, pH, neuron-specific enolase (NSE) and S100B. Doppler measurements and Doppler echocardiographic examinations were performed 5 min before the first umbilical cord occlusions and 3 min after each successive occlusion.

RESULTS

In experimental group animals, UCO caused a large decline in arterial PaO(2) (to approximately 7.70 mmHg, p < 0.01), a modest decline in pH (to approximately 7.24, p < 0.01), and a modest rise in PaCO(2) (to approximately 53.31 mmHg, p < 0.01), with a return more or less to baseline after occluder release. and there was significant change as compared with the control animals (all p < 0.01) with cumulative changes in responses to repetitive cord occlusions. The DV-PIV waveforms, right ventricle (RV) and LV Tei indices, the serum levels of NSE and S100B increased with cord occlusions (all p < 0.05), and were significantly higher than the control animals (all p < 0.05) with a cumulative changes in responses to repetitive cord occlusions. RV and LV Tei indices were significantly correlated with PaO(2) (r = - 0.684, p < 0.01 and r = - 0.725, p < 0.01), PaCO(2) (r = 0.682, p < 0.01 and r = 0.780, p < 0.01), pH (r = - 0.538, p < 0.01 and r = - 0.681, p < 0.01), NSE (r = 0.653, p < 0.01 and r = 0.687, p < 0.01), and S100B (r = 0.606, p < 0.01 and r = 0.640, p < 0.01). Significant but weaker correlations were also present between DV-PIV and the parameters considered.

CONCLUSION

Umbilical cord occlusion during the latter part of the pregnancy, enough to cause significant hypoxemia and acidosis, results in a significant increase of DV-PIV, RV and LV Tei indices, and the serum levels of NSE and S100B. There was a strong correlation between the RV and LV Tei indices and blood gas, pH, and NSE, S100B with hypoxia. Therefore, the Tei index might be an easy and useful quantitative parameter for assessing fetal hypoxic ischemia.

Pitavastatin prevents NMDA-induced retinal ganglion cell death by suppressing leukocyte recruitment

Excitotoxicity is a major cause of retinal ganglion cell (RGC) death during ischemic diseases such as vessel occlusion and diabetic retinopathy. However, the underlying mechanisms are not well understood. Statins, inhibitors of the HMG-CoA reductase, have neuroprotective effects in addition to their original role in lowering cholesterol. We hypothesize that pitavastatin, a recently introduced potent statin, is protective against N-methyl-d-aspartic acid (NMDA)-induced RGC death. Pitavastatin, administered by gavage, abolished NMDA-induced loss of RGCs. To elucidate the mechanisms underlying the neuroprotective effect of pitavastatin, we investigated its impact on inflammation. NMDA increased the expression of interleukin-1beta and TNF-alpha, and endothelial adhesion molecules, including ICAM-1, and induced leukocyte accumulation in the retinal vessels. Pitavastatin significantly reduced NMDA-induced leukocyte accumulation and up-regulation of endothelial adhesion molecules, whereas cytokine expression was unaffected. Systemic blockade of ICAM-1 in wild-type mice or absence of CD18 in gene-deficient (CD18(-/-)) mice significantly suppressed NMDA-induced leukocyte accumulation and RGC death. These findings suggest a novel and causative role for inflammatory leukocyte recruitment in NMDA-induced excitotoxicity. Furthermore, we show the novel neuroprotective effect of statins against excitotoxicity-induced RGC death. Statins or other anti-inflammatory agents may thus have therapeutic benefits in excitotoxicity-associated neuronal diseases through blockade of leukocyte recruitment.

Postischemic Alterations of BDNF, NGF, HSP 70 and Ubiquitin Immunoreactivity in the Gerbil Hippocampus: Pharmacological Approach

1. We investigated the immunohistochemical alterations of BDNF, NGF, HSP 70 and ubiquitin in the hippocampus 1 h to 14 days after transient cerebral ischemia in gerbils. We also examined the effect of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor pitavastatin against the changes of BDNF, NGF, HSP 70 and ubiquitin in the hippocampus after cerebral ischemia in the hippocampus after ischemia. 2. The transient cerebral ischemia was carried out by clamping the carotid arteries with aneurismal clips for 5 min. 3. In the present study, the alteration of HSP 70 and ubiquitin immunoreactivity in the hippocampal CA1 sector was more pronounced than that of BDNF and NGF immunoreactivity after transient cerebral ischemia. In double-labeled immunostainings, BDNF, NGF and ubiquitin immunostaining was observed both in GFAP-positive astrocytes and MRF-1-positive microglia in the hippocampal CA1 sector after ischemia. Furthermore, prophylactic treatment with pitavastatin prevented the damage of neurons with neurotrophic factor and stress proteins in the hippocampal CA1 sector after ischemia. 4. These findings suggest that the expression of stress protein including HSP 70 and ubiquitin may play a key role in the protection against the hippocampal CA1 neuronal damage after transient cerebral ischemia in comparison with the expression of neurotrophic factor such as BDNF and NGF. The present findings also suggest that the glial BDNF, NGF and ubiquitin may play some role for helping surviving neurons after ischemia. Furthermore, our present study indicates that prophylactic treatment with pitavastatin can prevent the damage of neurons with neurotrophic factor and stress proteins in the hippocampal CA1 sector after transient cerebral ischemia. Thus our study provides further valuable information for the pathogenesis after transient cerebral ischemia.

Time dependent alterations of co-localization of S100β and GFAP in the MPTP-treated mice

S100beta is a calcium-binding peptide produced by astrocytes. This protein is expressed at high levels in brain and is known as a marker of brain damage. However, little is known about the role of S100beta protein during neuronal damage caused by MPTP. To determine exactly changes of expression of S100beta protein in relation to changes of glial cells, we investigated immunohistochemically the expression of S100beta protein using MPTP-treated mice. The present study showed that tyrosine hydroxylase (TH) immunoreactivity was decreased in the striatum and substantia nigra from 5 h and 1 day after MPTP treatment, respectively. Thereafter, a severe reduction in TH immunoreactivity was observed in the striatum and substantia nigra 1, 3 and 7 days after MPTP treatment. In our double-labeled immunostaining, the number of S100-positive/GFAP-negative cells decreased from 1 day up to 7 days after MPTP treatment. In contrast, the number of double-labeled S100/GFAP-immnoreactive cells increased from 1 day up to 7 days after MPTP treatment. The number of S100beta-positive/GFAP-negative cells also decreased 3 and 7 days after MPTP treatment. In contrast, the number of double-labeled S100beta/GFAP-immunoreactive cells increased from 1 day up to 7 days after MPTP treatment. The present study demonstrates that S100beta/GFAP-positive cells may play some role in the pathogenesis of MPTP-induced dopaminergic neurodegeneration in the striatum. The present results also suggest the presence of the S100beta protein in a subpopulation of GFAP-negative astrocytes in the striatum after MPTP treatment. These results suggest that the modulation of astrocytic activation may offer a novel therapeutic strategy of Parkinson's disease.

Neuroprotective effect of arundic acid, an astrocyte-modulating agent, in mouse brain against MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) neurotoxicity

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes the damage of dopaminergic neurons as seen in Parkinson's disease. Oxidative stress has been as one of several pathogenic hypotheses for Parkinson's disease. Here we investigated whether arundic acid, an astrocyte-modulating agent, can protect against alterations of nitric oxide synthase (NOS) and superoxide dismutase (SOD) expression on MPTP neurotoxicity in mice, utilizing an immunohistochemistry. For this purpose, anti-tyrosine hydroxylase (TH) antibody, anti-dopamine transporter (DAT) antibody, anti-Cu/Zn-SOD antibody, anti-Mn-SOD antibody, anti-nNOS antibody, anti-eNOS antibody and anti-iNOS antibody were used. The present study showed that the arundic acid had a protective effect against MPTP-induced neuronal damage in the striatum and substantia nigra of mice. The protective effect may be, at least in part, caused by the reductions of the levels of reactive nitrogen (RNS) and oxygen species (ROS) against MPTP neurotoxicity. These results suggest that the pharmacological modulation of astrocyte may offer a novel therapeutic strategy for the treatment of Parkinson's disease. Furthermore, our results provide further evidence that a combination of nNOS inhibitors, iNOS inhibitors and free radical scavengers may be effective in the treatment of neurodegenerative diseases. Thus our present results provide valuable information for the pathogenesis of degeneration of the nigrostriatal dopaminergic neuronal pathway.

Alterations of interneurons of the gerbil hippocampus after transient cerebral ischemia: effect of pitavastatin

We investigated the immunohistochemical alterations of parvalbumin (PV)-expressing interneurons in the hippocampus after transient cerebral ischemia in gerbils in comparison with neuronal nitric oxide synthase (nNOS)-expressing interneurons. We also examined the effect of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor pitavastatin against the damage of neurons and interneurons in the hippocampus after cerebral ischemia. Severe neuronal damage was observed in the hippocampal CA1 pyramidal neurons 5 and 14 days after ischemia. The PV immunoreactivity was unchanged up to 2 days after ischemia. At 5 and 14 days after ischemia, in contrast, a conspicuous reduction of PV immunoreactivity was observed in interneurons of the hippocampal CA1 sector. Furthermore, a significant decrease of PV immunoreactivity was found in interneurons of the hippocampal CA3 sector. No damage of nNOS-immunopositive interneurons was detected in the gerbil hippocampus up to 1 day after ischemia. Thereafter, a decrease of nNOS immunoreactive interneurons was found in the hippocampal CA1 sector up to 14 days after ischemia. Pitavastatin significantly prevented the neuronal cell loss in the hippocampal CA1 sector 5 days after ischemia. Our immunohistochemical study also showed that pitavastatin prevented significant decrease of PV- and nNOS-positive interneurons in the hippocampus after ischemia. Double-labeled immunostainings showed that PV immunoreactivity was not found in nNOS-immunopositive interneurons of the brain. The present study demonstrates that cerebral ischemia can cause a loss of both PV- and nNOS-immunoreactive interneurons in the hippocampal CA1 sector. Our findings also show that the damage to nNOS-immunopositive interneurons may precede the neuronal cell loss in the hippocampal CA1 sector after ischemia and nNOS-positive interneurons may play some role in the pathogenesis of cerebral ischemic diseases. Furthermore, our present study indicates that pitavastatin can prevent the damage of interneurons in the hippocampus after cerebral ischemia. Thus, our study provides valuable information for the pathogenesis after cerebral ischemia.

Statins and stroke

Inhibitors of HMG-CoA reductase (statins) are potent cholesterol-lowering drugs. Large clinical trials have shown that statins reduce the incidence of cerebrovascular events, which might be surprising because cholesterol is not an established risk factor for stroke. In addition to their cholesterol-lowering properties, statins exert a number of pleiotropic, vasculoprotective actions that include improvement of endothelial function, increased nitric oxide (NO) bioavailability, antioxidant properties, inhibition of inflammatory responses, immunomodulatory actions, regulation of progenitor cells, and stabilization of atherosclerotic plaques. In fact, statins augment cerebral blood flow and confer significant protection in animal models of stroke partly via mechanisms related to the upregulation of endothelial nitric oxide synthase. Retrospective clinical evidence suggests that long-term statin administration may not only reduce stroke risk but also improve outcome. Early secondary prevention trials are underway to test the hypothesis that statin treatment initiated immediately after an event improves short-term outcome. Lastly, recent evidence suggests that sudden discontinuation of statin treatment leads to a rebound effect with downregulation of NO production. Withdrawal of statin treatment may impair vascular function and increase morbidity and mortality in patients with vascular disease.

Effects of chronic administration with nilvadipine against immunohistochemical changes related to aging in the mouse hippocampus

We investigated the effect of Ca2+ antagonist nilvadipine on age-related immunohistochemical alterations in ubiquitin and S100beta protein of the hippocampal CA1 sector in mice using 8-, 18-, 40-, and 59-week-old mice. No significant changes in the number of neuronal cells were observed in the hippocampal CA1 sector up to 59 weeks after birth. The administration of nilvadipine did not affect the number of the hippocampal CA1 cells of 40-week-old mice. Age-dependent increases in ubiquitin immunoreactivity were observed in the hippocampal CA1 neurons up to 59 weeks after birth. The administration of nilvadipine prevented dose-dependently the increases in the number of ubiquitin-immunoreactive neurons in the hippocampal CA1 sector of 40-week-old mice. S100,beta immunoreactivity was unchanged in the hippocampal CA1 sector up to 40 weeks after birth. In 59-week-old mice, the level of staining of S100beta-immunoreactive cells increased significantly in the hippocampal CA1 sector. The administration of nilvadipine decreased dose-dependently the number of S 100beta-immunoreactive cells in the hippocampal CA1 sector of 40-week-old mice. The present study demonstrates that age-related increases in ubiquitin system may play a pivotal role in protecting neuronal cell damage during aging. In contrast, our results suggest that expression of S 100beta protein in the hippocampal CA1 sector may play an exacerbating factor in some neuronal cells damaged by aging. Our results also demonstrate that nilvadipine, a dihydropyridine-type calcium channel blocker, can prevent dose-dependently the increases in the ubiquitin immunoreactive neurons and decrease the number of S100beta immunoreactive cells in the hippocampal CA1 neurons of aged mice. These results suggest that nilvadipine may offer a new approach for the treatment of neuronal dysfunction in aged humans.

HMG CoA reductase inhibitors reduce ischemic brain injury of Wistar rats through decreasing oxidative stress on neurons

Statins possess neuroprotective effect against ischemic damage, but how they protect neurons is not exactly made clear. We speculated that anti-oxidative property of statins is implicated, and investigated statins' influences on the oxidative neuronal damage in the brain after ischemia. After 14 days of atorvastatin, pitavastatin, simvastatin, or vehicle administration, 90 min of middle cerebral artery occlusion was imposed on Wistar rats. The production of 4-hydroxynonenal (HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), both of which are oxidative stress markers, as well as infarction formation were investigated at 1 day after the reperfusion. In the vehicle group, massive infarction was confirmed and HNE and 8-OHdG are robustly produced. In the statins-treated group, the infarction was smaller and the HNE and 8-OHdG production was less prominent than the vehicle group. Among the statins investigated, simvastatin was most effective for reducing oxidative stress and infarction volume, which may be brought by its highly lipophilic property. Reduction of oxidative stress by statins may be one main reason in ameliorating ischemic brain damage in rats.

Biphasic Effect of HMG-CoA Reductase Inhibitor, Pitavastatin, on Vascular Endothelial Cells and Angiogenesis

BACKGROUND

HMG-CoA reductase inhibitors (statins) have pleiotropic effects beyond their cholesterol-lowering effect. However, consensus on the effect of statins on endothelial cells and angiogenesis has not yet been reached.

METHODS AND RESULTS

The effects of pitavastatin on the migration, proliferation and viability of human epidermal microvessel endothelial cells (HMVECs) were examined using scratch assay, chemotaxis chamber, bromodeoxyuridine incorporation, trypan blue dye exclusion test, and nuclear DNA staining. Pitavastatin enhanced the migration, proliferation and viability of HMVECs at a low concentration (0.01 micromol/L) but inhibited them at high concentration (1 micromol/L). The inhibitory effect on cell viability by high concentration of pitavastatin was recovered by geranylgeranyl pyrophosphate, but the effect on migration and proliferation was not. The cell activating effect of a low concentration of pitavastatin was reversed by both farnesyl pyrophosphate and geranylgeranyl pyrophosphate. A quail chorioallantoic membrane assay showed that high concentration (1 micromol/L) of pitavastatin reduced fibroblast growth factor-2-induced angiogenesis, whereas low concentration (0.3 micromol/L) tended to increase angiogenesis.

CONCLUSION

Pitavastatin has a biphasic effect on HMVECs and on angiogenesis through at least 2 different pathways that include the mevalonate pathway.