Online monitoring of epithelial barrier kinetics and cell detachment during cisplatin-induced toxicity of renal proximal tubule cells.

Real-time and non-invasive assessment of tissue health is crucial for maximizing the potential of microphysiological systems (MPS) for drug-induced nephrotoxicity screening. Although impedance has been widely considered as a measure of the barrier function, it has not been incorporated to detect cell detachment in MPS with top and bottom microfluidic channels separated by a porous membrane. During cell delamination from the porous membrane, the resistance between both channels decreases, while capacitance increases, allowing the detection of such detachment. Previously reported concepts have solely attributed the decrease in the resistance to the distortion of the barrier function, ignoring the resistance and capacitance changes due to cell detachment. Here, we report a two-channel MPS with integrated indium tin oxide (ITO) electrodes capable of measuring impedance in real time. The trans-epithelial electrical resistance (TEER) and tissue reactance (capacitance) were extracted from the impedance profiles. We attributed the anomalous initial increase observed in TEER, upon cisplatin administration, to the distortion of tight junctions. Cell detachment was captured by sudden jumps in capacitance. TEER profiles illuminated the effects of cisplatin and cimetidine treatments in a dose-dependent and polarity-dependent manner. The correspondence between TEER and barrier function was validated for a continuous tissue using the capacitance profiles. These results demonstrate that capacitance can be used as a real-time and non-invasive indicator of confluence and will support the accuracy of the drug-induced cytotoxicity assessed by TEER profiles in the two-channel MPS for the barrier function of a cell monolayer.

Evaluation of Gastroprotective Activity of the Methanolic Extract of Justicia pectoralis Jacq. (Acanthaceae).

INTRODUCTION: Justicia pectoralis Jacq. is traditionally applied in folk medicine in Brazil and in several Latin American countries. The leaves are used in tea form, especially in the treatment of respiratory disorders, acting as an expectorant. It also has activity in gastrointestinal disorders, and it is anti-inflammatory, antioxidant, sedative, and estrogenic, among others. AIMS: To investigate the gastroprotective activity of the methanol extract of the leaves of Justicia pectoralis Jacq. (MEJP) in different experimental models of gastric ulcers. MATERIALS AND METHODS: The adult leaves of Justicia pectoralis Jacq. were collected and cultivated in beds, with an approximate spacing of 40 × 40 cm, organic fertilization, irrigation with potable water and without shelter from light. The MEJP was prepared from the dried and pulverized leaves and concentrated under reduced pressure in a rotary evaporator. For the experimental model of gastric ulcer, Swiss male albino mice were used. The inputs used in the experiment were MEJP at three different concentrations (250, 500 and 1000 mg/kg p.o.), cimetidine (50 mg/kg p.o.), indomethacin (50 mg/kg s.c.) and vehicle (10 mL/kg p.o.). RESULTS: MEJP (250, 500 and 1000 mg/kg p.o.) demonstrated gastroprotective activity, with levels of protection of 45.65%, 44.80% and 40.22%, respectively, compared to the control (vehicle). Compared with cimetidine (48.29%), MEJP showed similar gastroprotective activity. CONCLUSIONS: This study demonstrated the gastroprotective activity of MEJP and contributes to validate the traditional use the species for gastric disorders and provides a pharmacological basis for its clinical potential.

Susceptibility of mouse cochlear hair cells to cisplatin ototoxicity largely depends on sensory mechanoelectrical transduction channels both Ex Vivo and In Vivo.

Cisplatin, a highly effective chemotherapeutic drug for various human cancers, induces irreversible sensorineural hearing loss as a side effect. Currently there are no highly effective clinical strategies for the prevention of cisplatin-induced ototoxicity. Previous studies have indicated that short-term cisplatin ototoxicity primarily affects the outer hair cells of the cochlea. Therefore, preventing the entry of cisplatin into hair cells may be a promising strategy to prevent cisplatin ototoxicity. This study aimed to investigate the entry route of cisplatin into mouse cochlear hair cells. The competitive inhibitor of organic cation transporter 2 (OCT2), cimetidine, and the sensory mechanoelectrical transduction (MET) channel blocker benzamil, demonstrated a protective effect against cisplatin toxicity in hair cells in cochlear explants. Sensory MET-deficient hair cells explanted from Tmc1Δ;Tmc2Δ mice were resistant to cisplatin toxicity. Cimetidine showed an additive protective effect against cisplatin toxicity in sensory MET-deficient hair cells. However, in the apical turn, cimetidine, benzamil, or genetic ablation of sensory MET channels showed limited protective effects, implying the presence of other entry routes for cisplatin to enter the hair cells in the apical turn. Systemic administration of cimetidine failed to protect cochlear hair cells from ototoxicity caused by systemically administered cisplatin. Notably, outer hair cells in MET-deficient mice exhibited no apparent deterioration after systemic administration of cisplatin, whereas the outer hair cells in wild-type mice showed remarkable deterioration. The susceptibility of mouse cochlear hair cells to cisplatin ototoxicity largely depends on the sensory MET channel both ex vivo and in vivo. This result justifies the development of new pharmaceuticals, such as a specific antagonists for sensory MET channels or custom-designed cisplatin analogs which are impermeable to sensory MET channels.

Cimetidine repurposed as a potential immunomodulatory agent against colorectal carcinoma: A systematic review.

OBJECTIVE: To determine the survival benefit and immunomodulatory effects of cimetidine pre-, peri- or post-operatively in patients with colorectal cancer (CRC). METHODS: A systematic review was conducted using PubMed and Cochrane Library to retrieve randomized control trials (RCTs) that investigated the effects of cimetidine on survival and immunomodulation via improvement in tumor infiltrating lymphocytes (TILs) and peripheral blood lymphocytes. The review was carried out in accordance with the extended Preferred Reporting Items for Systematic Reviews and Meta-analyses. RESULTS: Four studies with the total of 267 patients were included in this systematic review. Treatment duration varied from 5 days to 1 year. Two studies reported a significant TIL response in the resected specimens after administering cimetidine, while one RCT showed an escalation of CD3, CD4 and CD57 lymphocytes in peripheral blood compared to the baseline following cimetidine treatment (p < 0.01). Of the three trials that examined the effects of cimetidine on survival, only two studies revealed significant survival benefit while the remaining study only showed a trend towards survival benefit. CONCLUSION: Repurposing of existing drugs like cimetidine has a potential to offer a survival benefit by acting as an immunomodulatory agent in patients undergoing curative resection for CRC. However, the heterogeneity seen in current studies and the evolvement of adjunctive therapies for CRC warrant large-scale, well-designed prospective RCTs to establish the efficacy of cimetidine in CRC.

Effect of Cimetidine on Metformin Pharmacokinetics and Endogenous Metabolite Levels in Rats.

Tubular secretion is a primary mechanism along with glomerular filtration for renal elimination of drugs and toxicants into urine. Organic cation transporters (OCTs) and multidrug and toxic extrusion (MATE) transporters facilitate the active secretion of cationic substrates, including drugs such as metformin and endogenous cations. We hypothesized that administration of cimetidine, an Oct/Mate inhibitor, will result in increased plasma levels and decreased renal clearance of metformin and endogenous Oct/Mate substrates in rats. A paired rat pharmacokinetic study was carried out in which metformin (5 mg/kg, intravenous) was administered as an exogenous substrate of Oct/Mate transporters to six Sprague-Dawley rats with and without cimetidine (100 mg/kg, intraperitoneal). When co-administered with cimetidine, metformin area under the curve increased significantly by 3.2-fold, and its renal clearance reduced significantly by 73%. Untargeted metabolomics was performed to investigate the effect of cimetidine on endogenous metabolome in the blood and urine samples. Over 8,000 features (metabolites) were detected in the blood, which were shortlisted using optimized criteria, i.e., a significant increase (P value < 0.05) in metabolite peak intensity in the cimetidine-treated group, reproducible retention time, and quality of chromatogram peak. The metabolite hits were classified into three groups that can potentially distinguish inhibition of i) extra-renal uptake transport or catabolism, ii) renal Octs, and iii) renal efflux transporters or metabolite formation. The metabolomics approach identified novel putative endogenous substrates of cationic transporters that could be tested as potential biomarkers to predict Oct/Mate transporter mediated drug-drug interactions in the preclinical stages. SIGNIFICANCE STATEMENT: Endogenous substrates of renal transporters in animal models could be used as potential biomarkers to predict renal drug-drug interactions in early drug development. Here we demonstrated that cimetidine, an inhibitor of organic cation transporters (Oct/Mate), could alter the pharmacokinetics of metformin and endogenous cationic substrates in rats. Several putative endogenous metabolites of Oct/Mate transporters were identified using metabolomics approach, which could be tested as potential transporter biomarkers to predict renal drug-drug interaction of Oct/Mate substrates.

Identification of Novel and Early Biomarkers for Cisplatin-induced Nephrotoxicity and the Nephroprotective Role of Cimetidine using a Pharmacometabolomic-based Approach Coupled with In Vitro Toxicodynamic Modeling and Simulation.

Cisplatin is widely used for the treatment of various types of cancer. However, cisplatin-induced nephrotoxicity (CIN) is frequently observed in patients receiving cisplatin therapy which poses a challenge in its clinical utility. Currently used clinical biomarkers for CIN are not adequate for early detection of nephrotoxicity, hence there is a need to identify potential early biomarkers in predicting CIN. In the current study, a combination of in vitro toxicodynamic (TD) modeling and untargeted global metabolomics approach was used to identify novel potential metabolite biomarkers for early detection of CIN. In addition, we investigated the protective role of cimetidine (CIM), an inhibitor of the organic cation transporter 2 (OCT2), in suppressing CIN. We first characterized the time-course of nephrotoxic effects of cisplatin (CIS) and the protective effects of CIM in a human pseudo-immortalized renal proximal tubule epithelial cell line (RPTEC), SA7K cell line. Secondly, we used a mathematical cell-level, in vitro TD modeling approach to quantitatively characterize the time-course effects of CIS and CIM as single agents and combination in SA7K cells. Based on the experimental and modeling results, we selected relevant concentrations of CIS and CIM for our metabolomics study. With the help of PCA (Principal Component Analysis) and PLS-DA (Projection to Latent Structure - Discriminate Analysis) analyses, we confirmed global metabolome changes for different groups (CIS, CIM, CIS+CIM vs control) in SA7K cells. Based on the criterion of a p-value ≤ 0.05 and a fold change ≥ 2 or ≤ 0.5, we identified 20 top metabolites that were significantly changed during the early phase i.e. within first 12 h of CIS treatment. Finally, pathway analysis was conducted that revealed the key metabolic pathways that were most impacted in CIN.

P19-derived neuronal cells express H1, H2, and H3 histamine receptors: a biopharmaceutical approach to evaluate antihistamine agents.

Histamine is a biogenic amine implicated in various biological and pathological processes. Convenient cellular models are needed to screen and develop new antihistamine agents. This report aimed to characterize the response of neurons differentiated from mouse P19 embryonal carcinoma cells to histamine treatment, and to investigate the modulation of this response by antihistamine drugs, vegetal diamine oxidase, and catalase. The exposure of P19 neurons to histamine reduced cell viability to 65% maximally. This effect involves specific histamine receptors, since it was prevented by treatment with desloratadine and cimetidine, respectively, H1 and H2 antagonists, but not by the H3 antagonist ciproxifan. RT-PCR analysis showed that P19 neurons express H1 and H2 receptors, and the H3 receptor, although it seemed not involved in the histamine effect on these cells. The H4 receptor was not expressed. H1 and H2 antagonists as well as vegetal diamine oxidase diminished the intracellular Ca2+ mobilization triggered by histamine. The treatment with vegetal diamine oxidase or catalase protected against mortality and a significant reduction of H2O2 level, generated from the cells under the histamine action, was found upon treatments with desloratadine, cimetidine, vegetal diamine oxidase, or catalase. Overall, the results indicate the expression of functional histamine receptors and open the possibility of using P19 neurons as model system to study the roles of histamine and related drugs in neuronal pathogenesis. This model is less expensive to operate and can be easily implemented by current laboratories of analysis and by Contract Research Organizations.

Drug screening in zebrafish larvae reveals inflammation-related modulators of secondary damage after spinal cord injury in mice.

Prolonged inflammation after spinal cord injury is detrimental to recovery. To find pharmacological modulators of the inflammation response, we designed a rapid drug screening paradigm in larval zebrafish followed by testing of hit compounds in a mouse spinal cord injury model. Methods: We used reduced il-1ß linked green fluorescent protein (GFP) reporter gene expression as a read-out for reduced inflammation in a screen of 1081 compounds in larval zebrafish. Hit drugs were tested in a moderate contusion model in mice for cytokine regulation, and improved tissue preservation and locomotor recovery. Results: Three compounds robustly reduced il-1ß expression in zebrafish. Cimetidine, an over-the-counter H2 receptor antagonist, also reduced the number of pro-inflammatory neutrophils and rescued recovery after injury in a zebrafish mutant with prolonged inflammation. Cimetidine action on il-1ß expression levels was abolished by somatic mutation of H2 receptor hrh2b, suggesting specific action. In mice, systemic treatment with Cimetidine led to significantly improved recovery of locomotor behavior as compared to controls, accompanied by decreased neuronal tissue loss and a shift towards a pro-regenerative profile of cytokine gene expression. Conclusion: Our screen revealed H2 receptor signaling as a promising target for future therapeutic interventions in spinal cord injury. This work highlights the usefulness of the zebrafish model for rapid screening of drug libraries to identify therapeutics to treat mammalian spinal cord injury.

Positron Emission Tomography-Based Pharmacokinetic Analysis To Assess Renal Transporter-Mediated Drug-Drug Interactions of Antimicrobial Drugs.

Transporter-mediated drug-drug interactions (DDIs) are of concern in antimicrobial drug development, as they can have serious safety consequences. We used positron emission tomography (PET) imaging-based pharmacokinetic (PK) analysis to assess the effect of different drugs, which may cause transporter-mediated DDIs, on the tissue distribution and excretion of [18F]ciprofloxacin as a radiolabeled model antimicrobial drug. Mice underwent PET scans after intravenous injection of [18F]ciprofloxacin, without and with pretreatment with either probenecid (150 mg/kg), cimetidine (50 mg/kg), or pyrimethamine (5 mg/kg). A 3-compartment kidney PK model was used to assess the involvement of renal transporters in the examined DDIs. Pretreatment with probenecid and cimetidine significantly decreased the renal clearance (CLrenal) of [18F]ciprofloxacin. The effect of cimetidine (-86%) was greater than that of probenecid (-63%), which contrasted with previously published clinical data. The kidney PK model revealed that the decrease in CLrenal was caused by inhibition of basal uptake transporters and apical efflux transporters in kidney proximal tubule cells. Changes in the urinary excretion of [18F]ciprofloxacin after pretreatment with probenecid and cimetidine resulted in increased blood and organ exposure to [18F]ciprofloxacin. Our results suggest that multiple membrane transporters mediate the tubular secretion of ciprofloxacin, with possible species differences between mice and humans. Concomitant medication inhibiting renal transporters may precipitate DDIs, leading to decreased urinary excretion and increased blood and organ exposure to ciprofloxacin, potentially exacerbating adverse effects. Our study highlights the strength of PET imaging-based PK analysis to assess transporter-mediated DDIs at a whole-body level.

N1 -Methylnicotinamide as Biomarker for MATE-Mediated Renal Drug-Drug Interactions: Impact of Cimetidine, Rifampin, Verapamil, and Probenecid.

N1 -methylnicotinamide (NMN) has been proposed as endogenous biomarker for drug-drug interactions mediated by inhibition of multidrug and toxin extrusion proteins (MATEs) at the renal proximal tubule. We analyzed NMN in plasma and urine samples of two clinical trials investigating a new probe drug cocktail (consisting of digoxin, metformin, furosemide, and rosuvastatin) dedicated to clinically relevant drug transporters. In trial 1, NMN was investigated after single-dose treatment with individual cocktail components or after cocktail treatment. In trial 2, NMN was investigated after treatment with cocktail alone or with cocktail + inhibitor (cimetidine, a MATE inhibitor; or rifampin, verapamil, or probenecid, inhibitors of other transporters). In trial 1, NMN kinetics in plasma and urine were essentially not affected by individual cocktail components or after cocktail treatment. In trial 2, NMN renal clearance from 0 to 12 hours (CLR,0-12 ) geometric mean ratio (GMR) after cocktail + cimetidine vs. cocktail alone was 75% (90% confidence interval (CI): 65-87%). NMN CLR GMR after cocktail + verapamil, + rifampin, or + probenecid vs. cocktail alone was 99% (90% CI: 81-121%), 91% (90% CI: 75-111%), and 107% (90% CI: 91-126%), respectively. Compared with creatinine CLR and creatinine area under the plasma-concentration time curve, NMN CLR was more specific and more sensitive for renal MATE inhibition. Absence of impact of the cocktail on NMN in trial 1 allows for utilization of NMN in studies using this transporter cocktail. Trial 2 data support that NMN CLR is a specific and sensitive marker for MATE-mediated renal drug-drug interactions.

Renal tubular transporter-mediated interactions between mirogabalin and cimetidine in rats.

Cimetidine at a clinical dosage decreased the renal clearance (CLr) of mirogabalin in humans by inhibition of renal secretion. Mirogabalin is a substrate of human OAT1/3, OCT2, MATE1 and/or MATE2-K. To clarify the mechanism behind the above interaction, it was investigated whether cimetidine inhibits the process of mirogabalin uptake at the basolateral side or the process of its efflux at the apical side in rat kidney in vivo.Cimetidine was administered to rats by a constant infusion to achieve an unbound plasma concentration of 7.0 µM and examine its effect on the renal disposition of [14C]metformin, [3H]p-aminohippuric acid (PAH), and [14C]mirogabalin.Cimetidine significantly induced the intrarenal accumulation of radioactivity (Kp, kidney) and decreased the renal clearance (CLr) of [14C]mirogabalin. These effects resulted in significantly decreased total clearance (CLt). Kp, kidney, and CLr of [14C]metformin, except CLt, were also affected, but no parameters of [3H]PAH were affected by cimetidine.These findings clarified that an unbound plasma concentration of cimetidine of 7.0 µM inhibited the apical efflux not the basolateral uptake of [14C]mirogabalin in rat kidney, suggesting that mirogabalin/cimetidine interaction was caused by inhibiting the apical efflux transporter, human MATE1 and/or MATE2-K, not the basolateral uptake transporter, human OCT2, in the kidney.

Characterization of the renal tubular transport of creatinine by activity-based protein profiling and transport kinetics.

Serum creatinine is widely used to adjust the dosing of drugs eliminated by the kidney in patients with renal dysfunction, as it is a readily accessible indicator of kidney function. However, there are many limitations for drug dosage adjustment based on serum creatinine levels, one of which is the limited understanding of creatinine's tubular transport. Thus, we aimed to complement and advance the renal tubular transport of creatinine by activity-based protein profiling (ABPP) and transporter-overexpression technology. Renal tubular transporters were not identified via ABPP due to the low-affinity interaction between transporters and creatinine. The uptake of isotopically labeled d3-creatinine was significantly increased in OCT2-overexpressing cell lines (p<0.01), and the Km and Vmax of d3-creatinine uptake mediated by OCT2 was 3.1 mM and 408 pmol/mg protein/min, respectively. In the OCT2-overexpressing cell lines, the IC50 of creatinine for d3-creatinine uptake was 10.3 mM, and that of the OCT2 inhibitor cimetidine for d3-creatinine uptake was 99.04 µM. Different dosages of creatinine did not affect the renal excretion of d3-creatinine in mice (p>0.05), while cimetidine significantly reduced the renal excretion of d3-creatinine (p<0.01) without affecting the glomerular filtration rate. Molecular docking in silico showed that the OCT2 amino acid GLN242 could form a hydrogen bond of 2.5 Å with creatinine, and there may be a π-π interaction between TYR362 and creatinine. A site mutation experiment demonstrated that TYR362 and GLN242 were important sites for the OCT2-creatinine interaction. These results demonstrate that OCT2 mediates the renal tubular secretion of creatinine with low affinity and is a minor contributor to creatinine secretion.

Cimetidine Does Not Inhibit 5-Aminolevulinic Acid Synthase or Heme Oxygenase Activity: Implications for Treatment of Acute Intermittent Porphyria and Erythropoietic Protoporphyria.

Acute intermittent porphyria (AIP) is characterized by acute neurovisceral attacks that are precipitated by the induction of hepatic 5-aminolevulinic acid synthase 1 (ALAS1). In erythropoietic protoporphyria (EPP), sun exposure leads to skin photosensitivity due to the overproduction of photoreactive porphyrins in bone marrow erythroid cells, where heme synthesis is primarily driven by the ALAS2 isozyme. Cimetidine has been suggested to be effective for the treatment of both AIP and EPP based on limited case reports. It has been proposed that cimetidine acts by inhibiting ALAS activity in liver and bone marrow for AIP and EPP, respectively, while it may also inhibit the hepatic activity of the heme catabolism enzyme, heme oxygenase (HO). Here, we show that cimetidine did not significantly modulate the activity or expression of endogenous ALAS or HO in wildtype mouse livers or bone marrow. Further, cimetidine did not effectively decrease hepatic ALAS activity or expression or plasma concentrations of the putative neurotoxic porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), which were all markedly elevated during an induced acute attack in an AIP mouse model. These results show that cimetidine is not an efficacious treatment for acute attacks and suggest that its potential clinical benefit for EPP is not via ALAS inhibition.

Anti-neoplastic action of Cimetidine/Vitamin C on histamine and the PI3K/AKT/mTOR pathway in Ehrlich breast cancer.

The main focus of our study is to assess the anti-cancer activity of cimetidine and vitamin C via combating the tumor supportive role of mast cell mediators (histamine, VEGF, and TNF-α) within the tumor microenvironment and their effect on the protein kinase A(PKA)/insulin receptor substrate-1(IRS-1)/phosphatidylinositol-3-kinase (PI3K)/serine/threonine kinase-1 (AKT)/mammalian target of rapamycin (mTOR) cue in Ehrlich induced breast cancer in mice. In vitro study was carried out to evaluate the anti-proliferative activity and combination index (CI) of the combined drugs. Moreover, the Ehrlich model was induced in mice via subcutaneous injection of Ehrlich ascites carcinoma cells (EAC) in the mammary fat pad, and then they were left for 9 days to develop obvious solid breast tumor. The combination therapy possessed the best anti-proliferative effect, and a CI < 1 in the MCF7 cell line indicates a synergistic type of drug interaction. Regarding the in vivo study, the combination abated the elevation in the tumor volume, and serum tumor marker carcinoembryonic antigen (CEA) level. The serum vascular endothelial growth factor (VEGF) level and immunohistochemical staining for CD34 as markers of angiogenesis were mitigated. Additionally, it reverted the state of oxidative stress and inflammation. Meanwhile, it caused an increment in apoptosis, which prevents tumor survival. Furthermore, it tackled the elevated histamine and cyclic adenosine monophosphate (cAMP) levels, preventing the activation of the (PKA/IRS-1/PI3K/AKT/mTOR) cue. Finally, we concluded that the synergistic combination provided a promising anti-neoplastic effect via reducing the angiogenesis, oxidative stress, increasing apoptosis,as well as inhibiting the activation of PI3K/AKT/mTOR cue, and suggesting its use as a treatment option for breast cancer.

Targeting organic cation transporters at the blood-brain barrier to treat ischemic stroke in rats.

Drug discovery and development for stroke is challenging as evidenced by few drugs that have advanced beyond a Phase III clinical trial. Memantine is a N-methyl-d-aspartate (NMDA) receptor antagonist that has been shown to be neuroprotective in various preclinical studies. We have identified an endogenous BBB uptake transport system for memantine: organic cation transporters 1 and 2 (Oct1/Oct2). Our goal was to evaluate Oct1/Oct2 as a required BBB mechanism for memantine neuroprotective effects. Male Sprague-Dawley rats (200-250 g) were subjected to middle cerebral artery occlusion (MCAO) for 90 min followed by reperfusion. Memantine (5 mg/kg, i.v.) was administered 2 h following intraluminal suture removal. Specificity of Oct-mediated transport was evaluated using cimetidine (15 mg/kg, i.v.), a competitive Oct1/Oct2 inhibitor. At 2 h post-MCAO, [3H]memantine uptake was increased in ischemic brain tissue. Cimetidine inhibited blood-to-brain uptake of [3H]memantine, which confirmed involvement of an Oct-mediated transport mechanism. Memantine reduced post-MCAO infarction and brain edema progression as well as improved neurological outcomes during post-stroke recovery. All positive effects of memantine were attenuated by co-administration of cimetidine, which demonstrates that Oct1/Oct2 transport is required for memantine to exert neuroprotective effects in ischemic stroke. Furthermore, Oct1/Oct2-mediated transport was shown to be the dominant mechanism for memantine brain uptake in the MCAO model despite a concurrent increase in paracellular "leak." These novel and translational findings provide mechanistic evidence for the critical role of BBB transporters in CNS delivery of stroke therapeutics, information that can help such drugs advance in clinical trials.

Dendritic cells activated by cimetidine induce Th1/Th17 polarization in vitro and in vivo.

Dendritic cells (DCs) are powerful antigen presentation cells and the initiator of adaptive immune response. Cimetidine, a widely used drug for gastric ulcers treatment, has significant immunomodulatory ability. However, the effects of cimetidine on DC-mediated T cell activation need to be further explored. In this study, we constructed the in vitro and in vivo model of cimetidine exposure, and our data showed that cimetidine stimulated the maturity of immature DCs, and further enhanced its T cell priming capacity. In vivo, the number of rat splenic CD103+ DC were not altered after cimetidine exposure, but the expression of surface markers CD54, CD11c, and MHC-II of which were up-regulated. Importantly, cimetidine interfered with DC-mediated T cell polarization, which was reflected in the up-regulation of Th1 and Th17 cells and the down-regulation of Th2 and Treg cells in vitro and in vivo. These results indicate that cimetidine can induce DC activation and promote DC mediated pro-inflammatory T cell response while weaken immunosuppressive T cell response.

Cimetidine and Ibuprofen Modulate T Cell Responses in a Mouse Model of Breast Cancer.

Cimetidine and ibuprofen exhibit immunomodulatory effects as an antagonist of histamine H2 receptor, and a cyclooxygenase inhibitor, respectively. Here, the effects of cimetidine and ibuprofen on some effector T cell-related parameters were investigated using a breast cancer (BC) model. BC was established in Balb/c mice using the 4T1 cell line. On day 10 after tumor induction, the BC-bearing mice were classified into four groups and treated with PBS, cimetidine (20 mg/kg), ibuprofen (20 mg/kg) or a combination of "cimetidine + ibuprofen" via intraperitoneal injection (daily from days 11 to 30). The mice were sacrificed on day 31 and the frequency of splenic Th1 and Treg cells, plasma IFN-γ and TGF-ß levels, and intra-tumoral T-bet, GATA3, FOXP3 and RORγt expressions were detected using flowcytometry, ELISA and real-time-PCR, respectively. In untreated cancerous mice, the percentage of splenic Th1 cells and plasma IFN-γ levels were lower (P<0.003 and P<0.01, respectively), whereas the percentage of splenic Treg cells and plasma TGF-ß levels were higher than in healthy mice (P<0.04 and P<0.005, respectively). Treatment of BC-bearing mice with cimetidine, ibuprofen or both drugs promoted the frequency of Th1 cells (P<0.05, P<0.007 and P<0.005, respectively) as well as IFN-γ levels (P<0.004, P<0.0001 and P<0.03, respectively), while reduced the frequencies of Treg cells (P<0.02, P<0.03 and P<0.01, respectively), TGF-ß levels (P<0.006, P<0.02 and P<0.002, respectively), intra-tumoral expression of FOXP3 (P<0.006, P<0.005 and P<0.005, respectively), and intra-tumoral expression of RORγt (P<0.04, P<0.03 and P<0.05, respectively) compared with untreated BC mice. The "cimetidine + ibuprofen"-treated mice displayed greater T-bet expression than the un-treated mice (P<0.006). Cimetidine and/or ibuprofen-treated BC-bearing mice exhibited reduced intra-tumoral expression of GATA3 compared with the untreated BC mice, but the differences were not significant. Cimetidine and ibuprofen correct some effector T cell-related parameters in cancerous mice. Immunotherapeutic potentials cimetidine and ibuprofen in cancers need investigations.

Effect of thallium on phototactic behaviour in Daphnia magna.

Thallium (Tl) is a trace metal enriched in wastewaters associated with mining and smelting of base metals. The toxicity of Tl to aquatic biota is poorly understood, particularly with respect to its sublethal effects. In this study, phototactic behavioural responses of naïve (i.e. no previous exposure to Tl) Daphnia magna, a key regulatory freshwater crustacean species, were examined in waters containing Tl. Fed and fasted neonate daphnids (< 24 h old) and fed adults (10-15 days old) showed no significant response at any tested water Tl concentration. However, in fasted adults, an increase in the positive phototactic response (measured as a greater number of daphnids closer to the light source after a 5-min exposure) was seen at Tl concentrations of 917 and 2099 µg L-1, values representative of extreme environmental Tl concentrations. The presence of Tl also decreased the swimming speed of adult Daphnia towards a light source. In the presence of cimetidine, a histamine receptor blocker, the increase in positive phototaxis induced by Tl disappeared, suggesting that Tl acts to perturb the phototaxis response through sensory inhibition. Conversely, although there was a trend towards enhanced activity, Tl had no significant effect on acetylcholinesterase, a marker of locomotor capacity.

Long-term exposure to cimetidine induced gonado-toxicity in male rats: Modulating role of Ocimum gratissimum.

BACKGROUND: Available evidence suggests that cimetidine is a reproductive toxicant that induces sexual and testicular dysfunction. Ocimum gratissimum (OG) is globally consumed for medicinal and nutritional purposes. To determine the modulating role of aqueous leaf extract of Ocimum gratissimum on cimetidine-induced gonado-toxicity, sexually mature male rats were randomized into four groups of six (n=6) rats each. Group A: control given 2ml distilled water. Group B received 500mg/kg body weight (bwt) of OG extract, Group C received 50mg/kg bwt cimetidine, and group D received 50mg/kg bwt of cimetidine+500mg/kg bwt OG extract once daily for 8 weeks via gastric gavage. Parameters tested include sperm parameters, testosterone (TT), luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin, testicular alkaline phosphatase (ALP), acid phosphatase (ACP), lactate dehydrogenase (LDH), protein, cholesterol, glycogen, sexual behavioural parameters, and testicular histology. RESULTS: There were depletions in the seminiferous epithelium, decreased sperm quality, TT, LH, and FSH, testicular enzymes, protein, cholesterol, glycogen, and sexual behaviour increase in animals treated with cimetidine only compared to control. OG restored and improved sexual behaviour and libido as evident from increased frequencies of mount, intromission, ejaculation, and ejaculatory latency. Mount latencies, intromission, post-ejaculation, and prolactin were significantly decreased. The significantly decreased testicular activities of ALP, ACP, LDH and protein, cholesterol, glycogen concentrations, TT, LH and FSH were increased by OG administration. CONCLUSION: Ocimum gratissimum attenuated the deleterious effects of cimetidine on the testis, protected the seminiferous epithelium, restored, and boosted sexual competence, and promoted spermatogenesis.

The Influence of Kidneys Ion Transport Inhibitors on the Pharmacokinetic and Tumor Uptake Behaviors of a HER2-targeted Small Size Radiolabeled Peptide.

BACKGROUND: HER2 over-expression plays a crucial role in the cancer treatment protocol. This study evaluates the effectiveness of organic anion and cation transport inhibitors and substrate on the tumor uptake of 99mTc- HYNIC-(Ser)3-LTVPWY radiotracer in SKOV-3 tumor-bearing nude mice. METHODS: Before the injection of the radiolabeled peptide, SKOV-3 tumor-bearing nude mice were treated with furosemide, cimetidine, para-amino hippuric acid, and saline. The inhibition effects of the organic anion and cation transport inhibitors were compared with the control group. In both treatment and control groups, the tumor and renal accumulation of radiopeptide in mice bearing SKOV-3 tumors were assessed in biodistribution and SPECT imaging studies. RESULTS: The biodistribution and imaging results suggested that all treated groups showed a higher tumor and higher normal tissue radioactivity compared to the control group. According to the tumor imaging study, the furosemidetreated group had slightly better tumor uptake and a higher tumor to muscle uptake ratio than other treatment groups. CONCLUSION: Administration of furosemide (an OAT inhibitor) increased radioactivity accumulation in the kidneys and blood and improved tumor radioactivity uptake. PAH (an anion transporter substrate) and cimetidine (an OCT inhibitor) have a minor effect on the accumulation of radioactivity in the kidneys and the acquired images.