Adipose tissue is now regarded as an active endocrine organ which can secrete various cytokines. Adipocyte-derived cytokines are termed adipocytokines (adipocytes+cytokine). Adipocytokines can affect vascular systems to prevent or exacerbate obesity-related vascular complications, including diabetes-related vascular dysfunction, hypertension, and atherosclerosis. However, their basic vascular functions remain to be fully determined. In this manuscript, I summarize our recent findings on the vascular effects of 5 newly identified adipocytokines (omentin, visfatin, nesfatin, vaspin, and chemerin), with a special focus on 1) vascular contractile reactivity, and 2) vascular inflammatory response/injury. These novel adipocytokines may be important future targets for the development of drugs and therapy for treating metabolic vascular disorders.
Increased oxidative stress is known to accelerate age-related pathologies. Beta-cryptoxanthin (β-CRX, (3R)-β,β-caroten-3-ol) is a potent antioxidant that is highly rich in Satsuma mandarin orange (mandarin), which is the most popular fruit in Japan. We investigated the antioxidative and anti-aging effects of β-CRX and mandarin using senescence-accelerated mice (SAMP10), which were characterized by a short lifespan, high generation of superoxide anions in the brain and poor learning ability with aging. β-CRX (0.5—5.0 μg/ml) or mandarin juice (3.8—38.0%) was added to drinking water of SAMP10 one to 12 months of age. β-CRX was dose-dependently incorporated into the cerebral cortex and the contents were similar to the concentration of β-CRX in the human frontal lobe. These mice also had higher learning ability. The level of DNA oxidative damage was significantly lower in the cerebral cortex of mice that ingested β-CRX and mandarin than control mice. In addition, the mice that ingested β-CRX (>1.5 μg/ml) and mandarin (>11.3%) exhibited a higher survival when 12 month-old, the presenile age of SAMP10, than control mice. These results suggest that β-CRX is incorporated into the brain and has an important antioxidative role and anti-aging effect.
A novel steroid compound, (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11), was found to be a partial agonist of the androgen receptor (AR) in an androgen responsive element (ARE)-luciferase reporter assay. YK11 accelerates nuclear translocation of AR. Furthermore, YK11 does not induce amino/carboxyl-terminal (N/C) interaction and prevents 5-α-dihydrotestosterone (DHT)-mediated N/C interaction. Thus, YK11 activates AR without causing N/C interaction, which may in turn be responsible for the partially agonistic nature of YK11 observed in the ARE-luciferase reporter system. YK11 acts as a gene-selective agonist of AR in MDA-MB 453 cells. The effect of YK11 on gene expression relative to that of androgen agonist varies depending on the gene context. YK11 activated the reporter gene by inducing the translocation of the AR into the nuclear compartment, where its amino-terminal domain (NTD) functions as a constitutive activator of AR target genes. Our results suggest that YK11 might act as selective androgen receptor modulator (SARM).
FXYD3, a regulator of Na, K-ATPase, was identified as an mRNA overexpressed in murine breast cancers induced by neu oncogene, which had inactivated transforming growth factor (TGF)-β signaling due to the defect of TGF-β receptor I (TβRI) expression. To elucidate whether the expression of FXYD3 mRNA was regulated by TGF-β signaling, we used a normal human mammary epithelial cell line, MCF-10A which responds to TGF-β and tumor necrosis factor (TNF)-α, followed by induction of epithelial-to-mesenchymal transition (EMT). Here, we showed that FXYD3 at plasma membrane in epithelial state of MCF-10A cells was decreased by treatment of TGF-β and TNF-α. The repression of FXYD3 mRNA induced by TGF-β and TNF-α in MCF-10A cells was abolished by TβRI inhibitor or Smad3 inhibitor, but not by small interfering RNA (siRNA) for Smad2. In addition, expression level of FXYD3 mRNA was up-regulated by the silencing of ZEB1/δEF1 transcriptional repressor which was a down-stream target gene of TGF-β and an inducer of EMT. On the other hand, expression level and cellular localization of E-cadherin and N-cadherin were not changed by siRNA for FXYD3 in MCF-10A and human breast cancer MCF-7 cells. These results suggest that FXYD3 is a target gene of TGF-β signaling through ZEB1/δEF1, but is not directly involved in EMT.
The roles of OmpC and OmpF in acidic resistance (AR) were examined. When ompC and ompF were deleted, AR was decreased. The decreased level of AR seen in the mutant that was deficient in ompC and ompF was elevated by the addition of glutamate, but not by the addition of arginine or lysine. The expression levels of adiA and cadB were diminished by the deletion of ompC and ompF, and the conversion of arginine to agmatine and lysine to cadaverine by intact cells were reduced in the mutant. The expression of gadA/gadB was not affected by the deletion of ompC and ompF. These results suggest that the transport of arginine, lysine, and their decarboxylated products through OmpC and/or OmpF is essential for the survival of Escherichia coli cells under extremely acidic conditions.
Escherichia coli has three major K+ uptake systems, Trk, Kup, and Kdp, which have been studied extensively at near neutral pH. However, the function of these transporters under acidic conditions is not well understood, although growth and survival under acidic conditions are important for bacterial pathogenesis. In this study, we examined the expression and activity of Kdp under acidic conditions and found that the transport activity of Kdp is decreased at low pH and that the expression of kdp is regulated by the internal K+ concentration in a pH-independent manner. Consequently, the low activity of Kdp was compensated for by the induction of its elevated expression by low K+ accumulation via Kdp at acidic pH.
We evaluated the capability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to discriminate twelve Escherichia strains: E. blattae, E. fergusonii, E. hermanii and nine E. coli, whose ribosomal RNA (rRNA) gene sequence homologies are in the range of 96—100%. Similarities obtained by MALDI-TOF MS were found to be 78—92% among the E. coli strains, and 74% between E. coli and E. fergusonii. E. blattae and E. hermanii showed only 32% similarity when compared to the other species. Thus, MALDI-TOF MS provides capability of distinguishing bacterial species or even strains possessing highly conserved rRNA gene sequences.
The protective effects of cyclic dipeptides in alcoholic beverages were investigated in the perfused guinea-pig hearts subjected to ischemia and reperfusion. Subsequently, in order to determine the importance of cyclic dipeptide structure, the effects of cyclo(L-Leu-L-Tyr) (cLY) were compared with those of the newly synthesized non-cyclic dipeptides, L-Leu-L-Tyr (LY) and L-Tyr-L-Leu (YL). After reperfusion, pressure recovery (%) in the left ventricle reached a peak of over 90% in the presence of cLY (10−6 M and 10−5 M) (control: 22.9%). The recovery by LY and YL was significantly lower than that by cLY, and ATP levels simultaneously monitored using 31P-NMR were already lower during the ischemic end period than those observed with cLY treatment. In perfused mitochondrial preparations, cLY significantly inhibited mitochondrial Ca2+ ([Ca2+]m) elevation in a similar way to that of the mitochondrial permeability transition pore (MPTP) inhibitor cyclosporin A. In vitro electron paramagnetic resonance (EPR) revealed that the active oxygen radicals quenching activity of cLY was greater than those of non-cyclic dipeptides. cLY inhibited caspase-3-induced apoptosis. The cyclic dipeptide structure inhibits opening of the MPTP by preventing [Ca2+]m overload-induced apoptosis related to mitochondrial active oxygen radical accumulation in ischemia-reperfusion hearts.
Hepatic stellate cells (HSCs), activated during liver injury, are defined as the most important target in the therapy of hepatic fibrosis. In the present study, we evaluated the effect of Rosmarinic acid (RosA) on the proliferation and apoptosis in activated hepatic stellate cells (HSC-T6), which is useful to decrease this cell population. The proliferation of HSC-T6 was significantly inhibited after treated with various concentrations of RosA for different times. Flow cytometric analyses and transmission electron microscope (TEM) observations revealed that HSC-T6 treated with RosA underwent apoptosis in a time dependent manner and displayed typical apoptotic features in the cells. The phosphorylation in signal transducer and activator of transcription protein-3 (STAT3), which regulates cell survival, proliferation and differentiation in a variety of tissues, was markedly decreased as the result of Western blot assay and correlated with downregulation of CyclinD1 and B cell lymphoma/leukemia-2 (Bcl-2). In conclusion, these results suggested that RosA was able to inhibit proliferation and induce apoptosis in HSC-T6, partly due to the inhibition of phosphorylation in STAT3, which contributed to the reversal of hepatic fibrosis.
Drug combinations have more potential advantage of greater analgesia than monotherapy. By the combination of analgesics with different mechanism, potency of analgesia can be maximized while the incidence of adverse effects is minimized. This study was aimed to assess a possible interaction in the antinociceptive effects between tramadol (T) and propacetamol (P) when administered in combination against nociceptive effects induced by physical or chemical injury in mice and rats. Three series of experiments were performed. The first was to determine effects of P and T alone or in combination in the acetic acid (AA)-induced writhing test in mice. Combination of T/P (3.9/67.5, 7.8/135, 15.6/271 mg/kg, intraperitoneally (i.p.)) elicited dose-dependent antinociception. The second determined whether the antinociceptive effects of the drugs observed in a test of persistent chemical pain could be seen in a test of acute thermal pain and the back-paw licking response was tested on the hot plate. The back-paw licking latency at different times after drugs obtained with the combination (16/270, 32/540 mg/kg, i.p. T/P) was longer than the respective values obtained with the individual agents. The third was designed to compare the antinociceptive effects between the drugs, either alone or in combination in the rat tail-flicks test. Combination of T/P (5.5/96, 11/192 mg/kg i.p.) both showed effects of higher potency than T and P, respectively. The data obtained confirmed that propacetamol is able to enhance the antinociceptive activity of tramadol.
Neuroimaging evidence showed structural and/or functional abnormalities existing in the central nervous system, especially the hippocampus, in chronic fatigue syndrome (CFS) patients. However, its pathophysiologic mechanisms are unclear in part due to the lack of an applicable animal model. We established a chronic fatigue murine model by six repeated injections of Brucella abortus antigen to mice, which was manifested as reduced daily running activity and hippocampal atrophy. Thereafter, resveratrol, a polyphenolic activator of sirtuin 1, was used for treatment in this model. Daily running activity was increased by more than 20%, and the hippocampus was enlarged after 4-week resveratrol therapy. Furthermore, resveratrol inhibited neuronal apoptosis and expression of hippocampal acetylated p53 in the fatigue mice. Resveratrol also improved neurogenesis and expression of brain-derived neurotrophic factor mRNA in the hippocamous. We concluded that repeated injection of B. abortus antigen could induce hypoactivity and hippocampal atrophy in mice. Resveratrol may be effective for improving fatigue symptoms and enlarging the atrophic hippocampus by repressing apoptosis and promoting neurogenesis.
The effect of naringin, a bioflavanoid, with potent antioxidant activity was studied on kainic acid (KA)-induced seizures, cognitive deficit and oxidative stress. Rats were administered KA (10 mg/kg intraperitoneally (i.p.)) and observed for behavioral changes and incidence and latency of convulsions over 4 h. The rats were thereafter sacrificed and oxidative stress parameters like malondialdehyde (MDA) and glutathione (GSH) were estimated in the brain. The level of proinflammatory cytokine, tumor necrosis factor (TNF)-α was also determined in the rat brain. It was observed that pretreatment with naringin (20, 40, 80 mg/kg, i.p.) significantly (p<0.001) increased the latency of seizures as compared to the vehicle treated-KA group. Naringin (40, 80 mg/kg) also significantly prevented the increase in MDA and fall in GSH levels due to KA. In addition, naringin dose-dependently attenuated the KA-induced increase in the TNF-α levels of brain. The pretreatment with naringin also significantly increased retention latency in the passive avoidance task. This shows that naringin reduced the cognitive deficit induced by KA. The results of our study suggest that naringin has therapeutic potential since it suppresses KA-induced seizures, cognitive impairment and oxidative stress in the brain. These neuroprotective effects are a result of its antioxidant and anti-inflammatory activity.
An overdose of acetaminophen (APAP) causes liver injury both in experimental animals and humans. N-Acetylcysteine (NAC) is clinically used as an antidote for APAP intoxication, and it is thought to act by providing cysteine as a precursor of glutathione, which traps a reactive metabolite of APAP. Other hepatoprotective mechanisms of NAC have also been suggested. Here, we examined the effects of thiol compounds with different abilities to restore hepatic glutathione, on hepatotoxicity of APAP and furosemide in mice. Overnight-fasted male CD-1 mice were given APAP or furosemide intraperitoneally. NAC, cysteine, glutathione, or glutathione-monoethyl ester was administered concomitantly with APAP or furosemide. All thiol compounds used in this study effectively protected mice against APAP-induced liver injury. Only glutathione-monoethyl ester completely prevented APAP-induced early hepatic glutathione depletion. Cysteine also significantly restored hepatic glutathione levels. NAC partially restored glutathione levels. Exogenous glutathione had no effect on hepatic glutathione loss. NAC and glutathione highly stimulated the hepatic expression of cytokines, particularly interleukin-6, which might be involved in the alleviation of APAP hepatotoxicity. Furosemide-induced liver injury, which does not accompany hepatic glutathione depletion, was also attenuated by NAC and exogenous glutathione, supporting their protective mechanisms other than replenishment of glutathione. In conclusion, exogenous thiols could alleviate drug-induced liver injury. NAC and glutathione might exert their effects, at least partially, via mechanisms that are independent of increasing hepatic glutathione, but probably act through cytokine-mediated and anti-inflammatory mechanisms.
Falcarindiol is a diacetylenic natural product containing unique carbon–carbon triple bonds. Mice were orally administrated falcarindiol (100 mg/kg), and drug-metabolizing and antioxidant enzymes were monitored in several tissues of mice. Treatment with falcarindiol was found to increase glutathione S-transferase (GST) and NAD(P)H: quinone oxidoreductase 1 activities in liver, small intestine, kidney, and lung. No changes were observed in cytochrome P450 (CYP) 1A known to activate procarcinogens. Western blot analysis revealed that various GST subunits including GSTA4, which plays an important role in the detoxification of alkenals produced from lipid peroxides, were induced in liver, small intestine, and kidney of falcarindiol-treated mice. Additionally, we investigated the protective effects of falcarindiol against hepatotoxicity induced by carbon tetrachloride (CCl4) and the mechanism of its hepatoprotective effect. Pretreatment with falcarindiol prior to the administration of CCl4 significantly suppressed both an increase in serum alanine transaminase/aspartate transaminase (ALT/AST) activity and an increase in hepatic thiobarbituric acid reactive substance levels without affecting CCl4-mediated degradation of CYP2E1. Formation of hexanoyl–lysine and 4-hydroxy-2(E)-nonenal–histidine adducts, lipid peroxidation biomarkers, in homogenates from the liver of CCl4-treated mice was decreased in the group of mice pretreated with falcarindiol. These results suggest that the protective effects of falcarindiol against CCl4 toxicity might, in part, be explained by anti-lipid peroxidation activity associated with the induction of the GSTs including GSTA4.
Sorafenib and sunitinib is a small molecule inhibitor of certain receptor tyrosine kinases, and have improved outcomes for patients with advanced renal cell carcinoma. Inhibitory concentration of 50% cell growth of sorafenib significantly rose to 6.4-fold in a multidrug resistance protein 2 (MRP2) transfected cell line versus control cell line. The concentration of sorafenib was significantly decreased to 74% of control cells after 3 h treatment. In contrast, a tyrosine kinase inhibitor sunitinib did not show alteration of inhibitory concentration of 50% cell growth and accumulation into the cells of MRP2 transfected cells. The present study suggest that sorafenib is a substrate for MRP2, suggesting that MRP2 may implicate drug resistance to sorafenib.
P-glycoprotein (P-gp), a drug efflux transporter, affects the pharmacokinetics of a wide range of substrate drugs. Our previous study clearly revealed that intestinal P-gp expression levels were decreased via an inducible nitric oxide synthase (iNOS)-mediated mechanism in the early phases of diabetes. Here, we focused on changes in ileal P-gp expression and the influences of NOS on the P-gp expression levels in the later phase of diabetic condition using streptozotocin (STZ)-induced diabetic mice. The ileal P-gp expression and activity was analyzed by Western blot analysis and by in situ closed loop method, respectively. In STZ-treated mice, ileal P-gp expression levels and activity significantly decreased on the 9th day after STZ administration. Interestingly, the decrease of P-gp function was recovered to the control level on 15th day in same conditioned mice. In addition, the recovery of P-gp expression levels was completely suppressed by a non-selective NOS inhibitor. These results indicate that the diabetic condition-induced decline of P-gp expression levels was temporary, and both decline- and recovery-process of intestinal P-gp expression levels are mediated by NOS. Furthermore, this study shows the bidirectional effect of NOS on regulation of intestinal P-gp expression.
Markedly inhibitory effects of Ca2+ on the growth of human tumor cells were attained through the induction of apoptosis in vitro. On the other hand, a good correlation between the growth inhibition effects of Ca2+ and the amounts of phosphatidylserines (PS) in the cell membranes (plasma membranes) was obtained. Furthermore, the decrease of membrane fluidity and the localization of lipid microdomains “lipid rafts” in the cell membranes were observed in the presence of Ca2+. The findings in this study suggest that Ca2+ could induce apoptosis toward tumor cells through the localization of lipid rafts in plasma membranes by the specific interactions between extracellular Ca2+ and PS.
Xiang-Qi-Tang (XQT) is a Chinese herbal formula containing Rhizoma Cyperi, Andrographis paniculata and Astragalus membranaceus. The present study investigated the effects of XQT on the mortality and inflammatory mediators in a chicken model challenged with avian pathogenic Escherichia coli (APEC). To detect the effect of XQT, the chickens were pretreated with the formula 12 h before being challenged with 108 colony forming unit (CFU) of APEC. The results showed that 0.6 g/kg XQT significantly elevated the survival rate of infected chickens. To further investigate the mechanism of decreasing mortality of XQT, we examined plasma inflammatory mediator levels. The levels of tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1) and soluble endothelial protein C receptor (sEPCR) were significantly increased in chickens challenged with APEC alone, whereas chickens pretreated with 0.6 g/kg XQT showed marked decrease of these inflammatory mediator levels during the death peak. Taken together, this study demonstrates that XQT has protective effects in APEC-treated chickens. The action mechanisms of XQT involve anti-inflammation and antithrombotic activity. These findings may contribute to future research on the action mechanisms of this formula, as well as prevention of or therapy for avian colibacillosis.
The prevention and treatment of diabetic complications are considered to be the most important for the general care of diabetic patients. We have been conducting pre-clinical animal experiments related to diabetes using Kangen-karyu, a Chinese prescription, to examine its therapeutic potential. In the present study, we further studied the anti-diabetic mechanism of Kangen-karyu, especially on the regulation of hyperglycemia-induced hepatic oxidative stress and inflammation in db/db mice. Kangen-karyu (100 or 200 mg/kg body weight/day, per os (p.o.) was administered every day for 18 weeks to db/db mice, and its effect was compared with vehicle-treated db/db and m/m mice. The administration of Kangen-karyu decreased the elevated serum and hepatic glucose concentration in db/db mice. The elevated expressions of p22phox and Nox-4 proteins (reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits) were significantly decreased after Kangen-karyu treatments. The oxidative stress-related markers in hepatic tissue (reactive oxygen species, reduced glutathione/oxidized glutathione ratio, and thiobarbituric acid-reactive substance) were also significantly ameliorated by the Kangen-karyu treatments. The db/db mice exhibited the up-regulation of nuclear factor-κBp65, cyclooxygenase-2, and inducible nitric oxide synthase levels in the liver; however, Kangen-karyu treatment significantly reduced those expressions. Taking these into consideration, our findings support the therapeutic evidence for Kangen-karyu ameliorating the development of diabetic hepatic damages via regulating oxidative stress and inflammation.
In an ongoing project directed toward the discovery of novel treatments for diabetic complications from traditional herbal medicines, six galloyl glucoses, 1,2,3-tri-O-galloyl-β-D-glucose (1), 1,2,6-tri-O-galloyl-β-D-glucose (2), 1,2,3,6-tetra-O-galloyl-β-D-glucose (3), 1,2,4,6-tetra-O-galloyl-β-D-glucose (4), 1,2,3,4,6-penta-O-galloyl-β-D-glucose (5), and tellimagrandin II (6), and two phenolic acids, gallic acid 4-O-β-D-glucoside (7) and gallic acid 4-O-β-D-(6′-O-galloyl)-glucoside (8), were isolated from an EtOAc-soluble fraction of the seeds of Cornus officinalis (Cornaceae). The structures of the compounds were identified using physical and spectroscopic methods, as well as by comparison of their data with values reported in the literature. All the isolates were evaluated in vitro for inhibitory activity against the formation of advanced glycation end-products (AGEs) and rat lens aldose reductase (RLAR). Compounds 1—6 were subjected to further bioassay to examine their inhibitory effects on AGE cross-linking. The opacity of lenses was significantly prevented when treated with 3 in an ex vivo experiment.
Hepatic organic anion transporters OATP1B1 and OATP1B3 are expressed at the sinusoidal membrane of hepatocytes and contribute to the hepatic uptake of a wide variety of clinically used drugs. To identify the antibiotics that interact with the human organic anion transporters OATP1B1 and OATP1B3, we applied a screening system using fluorescent probes. Twenty-six antibiotics with a variety of mechanisms of action were examined. The screening demonstrated that four antibiotics inhibited OATP1B1-mediated transport and 11 antibiotics inhibited OATP1B3-mediated transport in a concentration-dependent manner. Antibiotics that inhibited OATP1B3-mediated transport tended to exhibit higher affinity than those that inhibited OATP1B1-mediated transport. To clarify whether the antibiotics that interacted with OATP1B1 and/or OATP1B3 were substrates for these transporters, an uptake study was performed. Rifampicin and penicillin were transported by both OATP1B1 and OATP1B3. Moreover, OATP1B3 was involved in the transport of ceftriaxone, cefmetazole, cefoperazone, and cefotaxime. Macrolides were not significantly transported by either transporter. In conclusion, the results demonstrated that our system is a useful method for the rapid screening of transporter–antibiotic interaction, and we found novel substrates. Our results indicate that OATP1B1 and/or OATP1B3 contribute to the transport process of some antibiotics, and that drug–drug interactions associated with these transporters could occur after the administration of antibiotics.
Angiogenesis, a process of construction of new blood capillaries, is crucial for tumor progression and metastasis. Our previous studies demonstrated that a component of green tea, epigallocatechin-3-gallate (EGCG), suppressed angiogenesis and subsequent tumor growth. In this study, to elucidate the detailed mechanism of the anti-angiogenic effect of EGCG and to enhance the antiangiogenic activity of EGCG, we designed and synthesized EGCG derivatives and examined their biological effect and intracellular localization in human umbilical vein endothelial cells (HUVECs). EGCG derivatives aminopentyl dideoxyEGCG and aminopentyl dideoxygallocatechin-3-gallate (cis-APDOEGCG and trans-APDOEGCG) had an enhanced inhibitory effect on the proliferation when used at more than 30 μM. To elucidate antiangiogenic effect of EGCG, we used a 1 μM concentration for subsequent experiments where no effect on proliferation was observed. These EGCG derivatives showed a stronger inhibitory effect on migration, invasion, and tube formation by HUVECs than the non-derivatized EGCG. Furthermore, the derivatives induced a change in the distribution of F-actin and subsequent morphology of the HUVECs. Next, we synthesized fluorescent TokyoGreen-conjugated EGCG derivative (EGCG-TG) and observed the distribution in HUVECs under a confocal laser scanning microscope. Abundant fluorescence was observed in the cells after a 3-h incubation, and was localized in mitochondria as well as in cytoplasm. These results suggest that EGCG was incorporated into the HUVECs, that a portion of it entered into their mitochondria.
The aim of the present work was to confirm the usefulness of the dissolution/permeation system (D/P system) in the estimation of human oral absorption of poorly water-soluble drugs. The D/P system, which can simultaneously evaluate drug absorption processes, dissolution and permeation, can predict the oral absorption of poorly water-soluble drugs in fasted and fed humans, with a correlation between in vivo oral absorption (% of absorbed) and in vitro permeated amount (% of dose/2 h) in the D/P system. The oral absorption (fraction of absorbed dose, %) of poorly water-soluble drugs in the fasted and fed states was predicted using the D/P system. The effect of food on the oral absorption of various drugs estimated by the D/P system significantly correlated with clinical data (correlation coefficient: r2=0.924). Moreover, the proportion of oral absorption of cilostazol was predicted to decrease with an increase in its dose strength, which significantly correlated with in vivo human absorption. Consequently, the D/P system was demonstrated to be a useful in vitro system for prediction of the oral absorption of poorly water-soluble drugs.
P-Glycoprotein is one of the most important transporters in the ATP binding cassette transporter. Moreover, it is well known that the efficacy of immunosuppressants, which are used after organ transplantation, is controlled by P-glycoprotein (P-gp). We investigated how ischemia/reperfusion (I/R), which occurs after transplantation, influences the expression level and function of P-gp. To clarify the influence of intestinal I/R on the localization of P-gp, an intestinal ischemia model was produced using a spring scale and surgical sutures for 1 h, followed by reperfusion for 24 h. The expression levels of mRNA and protein of P-gp were examined. The protein expression levels of P-gp in ileal homogenate and the brush border membrane (BBM) were significantly decreased until 3 h after reperfusion. While the protein expression level of P-gp in homogenate showed a tendency to increase, that in the BBM continued to significantly decrease until 24 h after reperfusion. In contrast, the protein expression level of P-gp in the basolateral membrane (BLM) increased significantly until 24 h after reperfusion. While no significant change in multidrug resistance (mdr)-1a mRNA was found, the levels of mdr-1b and mdr-2 significantly increased during intestinal I/R. In addition, the levels of inflammatory cytokines mRNA and nitric oxide (NO) also significantly increased. It was shown that mdr-1b and mdr-2 mRNA strongly participate in the recovery of P-gp protein level after intestinal I/R. We detected the abnormal localization of P-gp in the ileal membrane during intestinal I/R, suggesting NO and/or inflammatory cytokines participate in the abnormal localization of P-gp.
Bupropion is an atypical antidepressant that is biotransformed in humans to its major active metabolite hydroxybupropion by cytochrome P450 2B6 (CYP2B6). Co-administration of bupropion with an inhibitor of CYP2B6 can result in a serious drug interaction, leading to bupropion related adverse effects (e.g. seizures). The antiplatelet agent ticlopidine has been identified as a potent in vitro inhibitor of bupropion hydroxylation, however it is unknown if it interacts in vivo in rodents. In this study we investigated the potential pharmacokinetic (PK) drug interaction between bupropion and ticlopidine in mice. Using a destructive sampling design, male CF-1 mice were administered ticlopidine 1.0 mg/kg daily for 5 d, followed by single-dose bupropion 50 mg/kg. Bupropion and hydroxybupropion levels were measured by HPLC-UV in plasma and brain tissues at 30, 60, 90, 120 and 180 min post-dose, and compared between treatment groups. There was a strong trend in both plasma and brain data towards greater bupropion levels and smaller hydroxybupropion levels in ticlopidine treated mice. Analysis of variance indicated statistical differences (p<0.05) at many time points. The variance associated with the area under the curve was calculated using Bailer's method and significant differences were found between treatment groups. Taken together, the concentration time point statistical analysis followed by PK modeling demonstrate a significant PK drug interaction between bupropion and ticlopidine. To our knowledge, this is the first study to document an in vivo drug interaction between these drugs in mice. Our findings support future in vivo drug interaction studies in mice between bupropion and CYP2B6 inhibitors.
The aim of this study was to determine whether a spermine (SPM)-induced increase in gastrointestinal absorption of an allergen leads to an anaphylactic response in sensitized mice. First, we examined the enhancing effect of SPM on the gastrointestinal absorption of ovalbumin (OVA) in an in situ jejunum loop study in rats and an in vivo oral absorption study in mice. Second, we investigated whether enhancement of gastrointestinal absorption of OVA caused by SPM induces an anaphylactic response in mice sensitized to OVA. In the in situ jejunum loop study in rats, a significant amount of immune-reactive OVA was detected in the plasma after co-administration of OVA and SPM. Oral co-administration of OVA and SPM to mice in vivo also increased plasma OVA concentrations in an SPM dose-dependent manner. Furthermore, in sensitized mice, a significant increase in plasma histamine levels occurred along with the increase in plasma OVA levels after co-administration of OVA with SPM. This finding suggests that an SPM-induced increase in gastrointestinal absorption of OVA leads to an anaphylactic response. These results indicate that excess oral ingestion of SPM may have widespread health effects, including the induction of food allergies, via modulation of the function of the gastrointestinal epithelial barrier.
Dimeric cinnamoylamide derivatives were synthetized and tested as inhibitors of tyrosinase activity and melanin formation. The most active dimeric cinnamoylamide derivatives was dimeric compound of p-coumaric acid (compound 1) that inhibited tyrosinase activity more efficiently than p-coumaric acid. It also inhibited melanin production by B16 melanoma cell line and normal human melanocytes more efficiently than kojic acid. We next investigated the potential mutagenic and skin sensitization effect of compound 1. Compound 1 was found to induce no mutagenic activity, no irritation and no delayed contact hypersensitivity at the maximum concentration of 10%. In vitro percutaneous absorption studies exhibited that compound 1 could diffuse across the skin till its site of action. All these results lead us to propose that compound 1 may be a safe and effective candidate for treating skin hyperpigmentation related disorders.