Involvement of the Restoration of Cerebral Blood Flow and Maintenance of eNOS Expression in the Prophylactic Protective Effect of the Novel Ferulic Acid Derivative FAD012 against Ischemia/Reperfusion Injuries in Rats.

Tissue plasminogen activator, aiming to restore cerebral blood flow (CBF), has been used for acute ischemic strokes in clinics; however, its narrow therapeutic time window remains a serious concern. To develop novel prophylactic drugs to alleviate cerebral ischemia/reperfusion injuries, ferulic acid derivative 012 (FAD012) was synthesized and showed comparable antioxidant properties to ferulic acid (FA) and probably possesses the potent ability to cross the blood-brain barrier. A more potent cytoprotective effect of FAD012 against H2O2-induced cytotoxicity in PC12 cells was also observed. In vivo toxicity was not observed in rats given a long-term oral administration of FAD012, indicating its good tolerability. A one-week-course oral administration of FAD012 significantly alleviated middle cerebral artery occlusion (MCAO)-induced cerebral ischemia/reperfusion injuries in rats, accompanied by the restoration of CBF and endothelial nitrogen oxide synthetase (eNOS) expression. Treatment with FAD012 significantly restored the cell viability and eNOS expression damaged by H2O2, used to mimic MCAO-triggered oxidative stress, in rat brain microvascular endothelial cells. Our findings suggested that FAD012 protected the viability of vascular endothelium and maintained eNOS expression, ultimately contributing to the restoration of CBF, and may provide a rationale for the development of FAD012 into an effective prophylactic drug for patients at high risk of stroke.

Enhanced Cytotoxic Effects of Arenite in Combination with Active Bufadienolide Compounds against Human Glioblastoma Cell Line U-87.

The cytotoxicity of a trivalent arsenic derivative (arsenite, AsIII) combined with arenobufagin or gamabufotalin was evaluated in human U-87 glioblastoma cells. Synergistic cytotoxicity with upregulated intracellular arsenic levels was observed, when treated with AsIII combined with arenobufagin instead of gamabufotalin. Apoptosis and the activation of caspase-9/-8/-3 were induced by AsIII and further strengthened by arenobufagin. The magnitude of increase in the activities of caspase-9/-3 was much greater than that of caspase-8, suggesting that the intrinsic pathway played a much more important role in the apoptosis. An increase in the number of necrotic cells, enhanced LDH leakage, and intensified G2/M phase arrest were observed. A remarkable increase in the expression level of γH2AX, a DNA damage marker, was induced by AsIII+arenobufagin. Concomitantly, the activation of autophagy was observed, suggesting that autophagic cell death associated with DNA damage was partially attributed to the cytotoxicity of AsIII+arenobufagin. Suppression of Notch signaling was confirmed in the combined regimen-treated cells, suggesting that inactivation of Jagged1/Notch signaling would probably contribute to the synergistic cytotoxic effect of AsIII+arenobufagin. Given that both AsIII and arenobufagin are capable of penetrating into the blood-brain barrier, our findings may provide fundamental insight into the clinical application of the combined regimen for glioblastoma.

Effects of hot­water extracts from 26 herbs on α­glucosidase activity.

α­glucosidase is a key enzyme that plays a role in glucose absorption in the gastrointestinal tract, and the inhibition of its activity induces the prevention of postprandial hyperglycemia. Several α­glucosidase inhibitors have been used as medicines for type 2 diabetes, but a similar effect is observed in natural resources, including traditional herbs and their phytochemicals. To identify the presence of the α­glucosidase inhibitory activity in herbs, in which various functional effects have been known to occur, the present study investigated the effects of hot­water extracts of 26 types of herbs on α­glucosidase activity in an in vitro assay. The results indicated significant increases in the inhibition of α­glucosidase activity in 1,000 µg/ml olive (P<0.01), white willow (P<0.01) and red rooibos hot­water extracts. Furthermore, ≥50% inhibition of α­glucosidase activity was determined to be significant in 1,000 µg/ml coltsfoot, green tea and bearberry hot­water extracts. In addition, the effects of bearberry, green tea and coltsfoot hot­water extracts on α­glucosidase activity in vivo were evaluated according to the blood glucose levels (BGLs) in maltose and glucose load model rats. It was indicated that the administration of these three herb extracts significantly reduced the increasing BGLs after maltose loading until 0.5 h compared with the control group. However, only coltsfoot extract significantly reduced the increasing BGLs after glucose loading until 0.5 h compared with the control group. Thus, the present results may facilitate the understanding of a novel functionality in traditional herbs, which could be useful for the prevention of disease onset and progression, such as in hyperglycemia and type 2 diabetes.

Protective Effects of Ferulic Acid against Chronic Cerebral Hypoperfusion-Induced Swallowing Dysfunction in Rats.

Ferulic acid (FA), a phenolic phytochemical, has been reported to exert antioxidative and neuroprotective effects. In this study, we investigated the protective effects of FA against the dysfunction of the swallowing reflex induced by ligation of bilateral common carotid arteries (2VO) in rats. In 2VO rats, topical administration of water or citric acid to the pharyngolaryngeal region evoked a diminished number of swallowing events with prolonged latency compared to sham-operated control rats. 2VO rats had an increased level of superoxide anion radical, and decreased dopamine and tyrosine hydroxylase enzyme levels in the striatum, suggesting that 2VO augmented cerebral oxidative stress and impaired the striatal dopaminergic system. Furthermore, substance P (SP) expression in the laryngopharyngeal mucosa, which is believed to be positively regulated by dopaminergic signaling in the basal ganglia, was decreased in 2VO rats. Oral treatment with FA (30 mg/kg) for 3 weeks (from one week before 2VO to two weeks after) improved the swallowing reflex and maintained levels of striatal dopamine and laryngopharyngeal SP expression in 2VO rats. These results suggest that FA maintains the swallowing reflex by protecting the dopamine-SP system against ischemia-induced oxidative damage in 2VO rats.

Effects of Etanercept against Transient Cerebral Ischemia in Diabetic Rats.

Diabetes mellitus is known to exacerbate acute cerebral ischemic injury. Previous studies have demonstrated that infarction volumes caused by transient cerebral ischemia were greater in diabetic rats than in nondiabetic rats. Tumor necrosis factor-α (TNF-α) is a proinflammatory protein produced in the brain in response to cerebral ischemia that promotes apoptosis. Etanercept (ETN), a recombinant TNF receptor (p75)-Fc fusion protein, competitively inhibits TNF-α. Therefore, we evaluated the neuroprotective effects of chronic or acute treatment with ETN on cerebral injury caused by middle cerebral artery occlusion/reperfusion (MCAO/Re) in rats with streptozotocin-induced diabetes. Furthermore, we evaluated the effects of ETN against the apoptosis and myeloperoxidase activity. Single administration of ETN before MCAO significantly suppressed exacerbation of cerebral damage in nondiabetic rats, as assessed by infarct volume. In contrast, the diabetic state markedly aggravated MCAO/Re-induced cerebral damage despite ETN treatment within 24 h before MCAO. However, the damage was improved by repeated administration of ETN at 900 µg/kg/daily in rats in an induced diabetic state. These results suggested that repeated administration of ETN can prevent exacerbation of cerebral ischemic injury in the diabetic state and is mainly attributed to anti-inflammatory effects.

Chronic Treatment with a Water-Soluble Extract from the Culture Medium of Ganoderma lucidum Mycelia Prevents Apoptosis and Necroptosis in Hypoxia/Ischemia-Induced Injury of Type 2 Diabetic Mouse Brain.

Type 2 diabetes mellitus has been known to increase systemic oxidative stress by chronic hyperglycemia and visceral obesity and aggravate cerebral ischemic injury. On the basis of our previous study regarding a water-soluble extract from the culture medium of Ganoderma lucidum mycelia (designed as MAK), which exerts antioxidative and neuroprotective effects, the present study was conducted to evaluate the preventive effects of MAK on apoptosis and necroptosis (a programmed necrosis) induced by hypoxia/ischemia (H/I) in type 2 diabetic KKAy mice. H/I was induced by a combination of unilateral common carotid artery ligation with hypoxia (8% O2 for 20 min) and subsequent reoxygenation. Pretreatment with MAK (1 g/kg, p.o.) for a week significantly reduced H/I-induced neurological deficits and brain infarction volume assessed at 24 h of reoxygenation. Histochemical analysis showed that MAK significantly suppressed superoxide production, neuronal cell death, and vacuolation in the ischemic penumbra, which was accompanied by a decrease in the numbers of TUNEL- or cleaved caspase-3-positive cells. Furthermore, MAK decreased the expression of receptor-interacting protein kinase 3 mRNA and protein, a key molecule for necroptosis. These results suggest that MAK confers resistance to apoptotic and necroptotic cell death and relieves H/I-induced cerebral ischemic injury in type 2 diabetic mice.

Orally administrated ascorbic acid suppresses neuronal damage and modifies expression of SVCT2 and GLUT1 in the brain of diabetic rats with cerebral ischemia-reperfusion.

Diabetes mellitus is known to exacerbate cerebral ischemic injury. In the present study, we investigated antiapoptotic and anti-inflammatory effects of oral supplementation of ascorbic acid (AA) on cerebral injury caused by middle cerebral artery occlusion and reperfusion (MCAO/Re) in rats with streptozotocin-induced diabetes. We also evaluated the effects of AA on expression of sodium-dependent vitamin C transporter 2 (SVCT2) and glucose transporter 1 (GLUT1) after MCAO/Re in the brain. The diabetic state markedly aggravated MCAO/Re-induced cerebral damage, as assessed by infarct volume and edema. Pretreatment with AA (100 mg/kg, p.o.) for two weeks significantly suppressed the exacerbation of damage in the brain of diabetic rats. AA also suppressed the production of superoxide radical, activation of caspase-3, and expression of proinflammatory cytokines (tumor necrosis factor-α and interleukin-1ß) in the ischemic penumbra. Immunohistochemical staining revealed that expression of SVCT2 was upregulated primarily in neurons and capillary endothelial cells after MCAO/Re in the nondiabetic cortex, accompanied by an increase in total AA (AA + dehydroascorbic acid) in the tissue, and that these responses were suppressed in the diabetic rats. AA supplementation to the diabetic rats restored these responses to the levels of the nondiabetic rats. Furthermore, AA markedly upregulated the basal expression of GLUT1 in endothelial cells of nondiabetic and diabetic cortex, which did not affect total AA levels in the cortex. These results suggest that daily intake of AA attenuates the exacerbation of cerebral ischemic injury in a diabetic state, which may be attributed to anti-apoptotic and anti-inflammatory effects via the improvement of augmented oxidative stress in the brain. AA supplementation may protect endothelial function against the exacerbated ischemic oxidative injury in the diabetic state and improve AA transport through SVCT2 in the cortex.

Antidepressant-like effects of a water-soluble extract from the culture medium of Ganoderma lucidum mycelia in rats.

BACKGROUND: Ganoderma lucidum is a popular medicinal mushroom used for promoting health and longevity in Asian countries. Previously, we reported that a water-soluble extract from a culture medium of Ganoderma lucidum mycelia (MAK) exerts antioxidative and cerebroprotective effects against ischemia-reperfusion injury in vivo. Here, we evaluated the antidepressant and anxiolytic activities of MAK in rats. METHODS: MAK (0.3 or 1 g/kg, p.o.) was administered in the experimental animals 60 min before the forced swimming, open-field, elevated plus-maze, contextual fear-conditioning, and head twitch tests. Additionally, the mechanisms involved in the antidepressant-like action of MAK were investigated by the serotonin precursor 5-hydroxy-L-tryptophan (5-HTP)- or 5-HT2A agonist (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI)-induced head twitch responses. RESULTS: Treatment with MAK (1 g/kg) exhibited antidepressant-like effects in the forced swimming test, attenuated freezing behavior in the contextual fear-conditioning test, and decreased the number of head twitches induced by DOI, but not with 5-HTP. No significant response was observed in locomotion or anxiety-like behavior, when the animals were evaluated in the open-field or elevated plus-maze test, respectively. CONCLUSIONS: These data suggest that MAK has antidepressant-like potential, which is most likely due to the antagonism of 5-HT2A receptors, and possesses anxiolytic-like effects toward memory-dependent and/or stress-induced anxiety in rats.

Regulation of CMV promoter-driven exogenous gene expression with doxorubicin in genetically modified cells.

The regulation of gene expression after the introduction of an exogenous gene is a problematic aspect of gene therapy. The purpose of this study was to use doxorubicin to regulate exogenous gene expression in a vector containing the cytomegalovirus (CMV) promoter. The pQBI25 vector, which encodes the CMV promoter and the cDNA for red-shifted green fluorescent protein (rsGFP), was transfected into a rat skin fibroblast cell line (FR cells). The pEGFP vector, encoding the CMV promoter and enhanced green fluorescent protein (EGFP) cDNA, was transfected into human hepatoma HepG2 cells. FR-pQBI25 cells were then continuously exposed to doxorubicin and methotrexate for 96 and 48 h, respectively; HepG2-pEGFP cells were continuously exposed to doxorubicin for 48 h. The levels of c-fos, c-jun and rsGFP mRNA, as well as the levels of rsGFP protein, in the FR-pQBI25 cells were found to be significantly higher following exposure to doxorubicin. However, the level of rsGFP protein was not changed by exposure to methotrexate. The level of EGFP protein in the HepG2-pEGFP cells was also significantly higher following exposure to doxorubicin. To examine the effect of cessation of doxorubicin exposure, FR-pQBI25 cells that had been exposed to doxorubicin for 48 h were re-plated in fresh medium without doxorubicin for a further 48 h. The increased levels of c-fos, c-jun and rsGFP mRNA and rsGFP protein seen after treatment with doxorubicin had reduced by 48 h after the cessation of exposure to doxorubicin. These findings suggest that CMV-driven exogenous gene expression may be regulated by doxorubicin.

Tissue distribution and hepatic subcellular distribution of perfluorooctanoic acid at low dose are different from those at high dose in rats.

Fate of perfluorooctanoic acid (PFOA) after an intravenous injection to male rats at the dose of 0.041 mg/kg body weight was compared with that at the dose of 16.56 mg/kg body weight. In the liver, 52% and 27% of PFOA dosed was recovered 2 h after an intravenous injection at the low and the high doses, respectively. By contrast, larger proportion of PFOA dosed was distributed to serum, other tissues and carcass at the high dose compared with the low dose. Subcellular distribution of PFOA was determined in the liver. At the dose of 0.041 mg/kg, 45%, 34%, 18% and 3% were distributed to 8000 g pellet, 18000g pellet, 105000g pellet and 105000g supernatant fraction, respectively; 28%, 17%, 13% and 43% of PFOA were distributed to these fractions, respectively, at the dose of 16.56 mg/kg. The higher the concentration of hepatic PFOA was, the more the PFOA was distributed to 105000g supernatant fraction. Biliary excretion index increased as PFOA concentration raised in the liver. These results suggest that PFOA is preferentially taken-up by the liver, and distributed to membrane fractions, especially 18000g pellet, and hardly excreted into bile when exposed at very low dose.

Effects of pioglitazone on stearoyl-CoA desaturase in obese Zucker fa/fa rats.

The effects of a peroxisome proliferator activated receptor gamma (PPARgamma) agonist on hepatic stearoyl-CoA desaturase (SCD) in insulin-resistant and obese Zucker fa/fa rats were studied. The administration of pioglitazone, a PPARgamma agonist, to Zucker obese rats greatly improved their insulin sensitivity. The treatment of Zucker obese rats with pioglitazone did not affect the index of fatty acid desaturation of either serum or liver. Hepatic SCD activity and the mRNA level of SCD1 were not changed by treatment of the rats with pioglitazone. The activity of palmitoly-CoA chain elongase, which is involved in the biosynthesis of oleic acid in concert with SCD, was not significantly altered when Zucker obese rats received pioglitazone. Although neither the activity nor mRNA expression of acyl-CoA oxidase was changed by treatment of Zucker obese rats with pioglitazone, the mRNA expressions of both sterol regulatory element-binding protein-1c and acetyl-CoA carboxylase sensitively responded to the challenge by pioglitazone. These results suggest that the insulin sensitivity of insulin-resistant and obese Zucker fa/fa rats is improved by pioglitazone independently of SCD activity.

Stearoyl-CoA desaturase activity is elevated by the suppression of its degradation by clofibric acid in the liver of rats.

A mechanism by which fibrates control stearoyl-CoA desaturase (SCD) in the liver was studied. Treatment of rats with 2-(4-chlorophenoxy)-2-methylpropionic acid (clofibric acid) or feeding of a fat-free diet markedly elevated hepatic activity of SCD. Both the treatment with clofibric acid and the feeding of the fat-free diet caused an increase in the steady-state level of SCD1 mRNA and enhanced transcriptional rate. The half-lives of SCD for control rats, rats treated with clofibric acid rats, and rats fed the fat-free diet were estimated to be 2.0, 3.9, and 1.9 h, respectively. Activity of palmitoyl-CoA chain elongase (PCE) was increased by both clofibric acid treatment and feeding of the fat-free diet as was observed with SCD. Steady-state level of rat fatty acid elongase 2 mRNA was increased by the treatment with clofibric acid or feeding of fat-free diet, although the transcriptional rate was not altered. Different from SCD, PCE was highly stable and its half-life was not changed by either clofibric acid or fat-free diet. These results strongly suggest that the decreased degradation of SCD is responsible for the increase in its activity in addition to increased transcription of SCD1 in the rats treated with clofibric acid.

Molecular properties and intracellular localization of rat liver nuclear scaffold protein P130.

We examined the molecular basis of rat P130, a nuclear scaffold protein, and its functions. P130 comprising 845 amino acid residues possesses several functional domains and yields an electrophoretically distinctive isoform, P123, by altering its phosphorylation status in association with translocation across the nuclear membrane and from the digitonin-extractable fraction of the nucleus to the nuclear scaffold. The functional domains, NLS, NES, and zinc-finger bearing DNA-binding domains, ZF1 and ZF2, aid these translocations. P130 binds RNA through two RNA-binding domains (RB1 and RB2) similar to those of hnRNPs I and L. Microsome- and polysome-localized P130 and P123 were found in rat liver and Ac2F hepatoma cells. This localization required prior entry of P130 to the nucleus, but did not require RB1 and RB2. Thus, P130 initially purified from rat liver nuclear scaffold has the potential to play a variety of roles in biological events not only in the nuclear scaffold but also in various subcellular compartments. P130 (AB205483) is identical to matrin 3 (M63485 and BC062231), although the primary structure of rat matrin 3 has been revised, since it was first published.

The galectin-3 gene promoter binding proteins in the liver of rats 48-h post-treatment with CCl4.

The present study was undertaken to characterize structure-function relationships of the rat galectin-3 gene promoter especially focusing on the promoter binding proteins included in livers injured with CCl4. Transcription start site determination identified a 66-nucleotide-long exon 1 of this gene. Transient expression analysis using a reporter luciferase gene assigned a region between -161 and -15 to the proximal promoter within the 1-kb region flanking the 5'-end of exon 1. The rat galectin-3 gene promoter possesses a Runx2 binding site and inverted repeats of Sp1 binding motifs in separate regions downstream from -117 as structures resembling those of the mouse galectin-3 gene promoter. The -161/-118 region bound two different proteins. One is a novel protein, a rat version of Purbeta that binds to a guanine nucleotide pair at -145 and -144 to modulate constitutive galectin-3 gene transcription. Southwestern blot analysis using the -161/-118 ligand revealed a signal of a 50-kDa protein in liver nuclear extracts from rats 48-h post-treatment with CCl4, but not in those from Ac2F cells and normal rat livers. The inducible nature of this protein suggested its distinctive role in galectin-3 induction in a liver injured with CCl4. E-box and peroxisome proliferator response element-like motifs reside on separate DNA strands from -140 to -135. Contribution of this segment to the regulation of galectin-3 gene transcription under pathological conditions was suggested, since a DNA ligand with the two motifs simultaneously mutagenized at -136 and -137 was not bound by the 50-kDa protein.

Development-associated myristoylated alanine-rich C kinase substrate phosphorylation in rat brain.

OBJECT: In neuronal cells, myristoylated alanine-rich C kinase substrate (MARCKS), localized to particular areas of the synaptic membrane, is active during brain development. The destination of phosphorylated MARCKS is thought to be the cytoplasm where it is probably inactive. We compared MARCKS phosphorylation in the brains of embryonic, perinatal, and adult rats to determine its possible involvement in neurogenesis. METHODS: We prepared crude and partially purified extracts from various brain regions of rats aged between embryonic day 14 (E14) and 7 weeks after birth and assayed them for MARCKS phosphorylation by immunochemical methods. The isotypes of protein kinase C (PKC) were immunochemically identified in crude brain extracts from embryonic and postnatal rats. Despite negligible MARCKS phosphorylation, E16 brain extracts contained both MARCKS and PKCgamma, delta, epsilon, and lambda. MARCKS and polypeptides were clearly phosphorylated (49 and 45 kDa, respectively) in brain extracts purified on a DE52 column. Embryonic brain extracts manifested a high-molecular-weight activity capable of suppressing polypeptide phosphorylation. This activity was markedly decreased on the day of birth and almost undetectable in the brains of 9-day-old rats. CONCLUSIONS: The embryonic rat brain appears to contain a protein(s) that suppresses the phosphorylation of other proteins including MARCKS. We posit that this inhibitory activity represents a factor(s) that plays a role in the regulation of neurogenesis beginning on the day on which MARCKS appears in the embryonic brain.