Intestinal Permeability and Oral Absorption of Selected Drugs Are Reduced in a Mouse Model of Familial Alzheimer's Disease.

Compared with the significant number of studies reporting altered abundance and function of drug transporters at the blood-brain barrier (BBB) in Alzheimer's disease (AD), the impact of AD on the abundance of intestinal drug transporters and the subsequent effects on oral drug absorption have received little attention. We have reported the altered abundance of some small intestinal drug transporters in a familial mouse model of AD; however, whether this leads to altered oral drug absorption is unknown. The current study examined plasma concentrations of caffeine and diazepam (markers for transcellular passive transport), digoxin (P-glycoprotein substrate), and valsartan (multidrug resistance-associated protein 2 substrate) following oral administration to 8-10 month old female wild-type (WT) and APPswe/PSEN1dE9 (APP/PS1) transgenic mice, a commonly used mouse model of familial AD. The plasma exposure of valsartan and digoxin was significantly (p < 0.05) lower in APP/PS1 animals compared with WT mice, whereas the plasma concentrations of the passive transcellular markers caffeine and diazepam did not significantly differ between the two genotypes. To assess whether the reduced oral absorption of valsartan and digoxin was due to decreased intestinal transport, the ex vivo transport of the previously mentioned drugs and mannitol (a marker of paracellular transport) across the jejunum of WT and APP/PS1 mice was assessed over 120 min. In line with the in vivo absorption studies, the permeability of caffeine and diazepam did not significantly differ between WT and APP/PS1 mice. The permeability of 3H-digoxin through the APP/PS1 mouse jejunum was lower than that measured through the WT jejunum; the average amount (relative to dose applied) permeating the tissue over 120 min was 0.22 ± 0.11% (mean ± SD) for the APP/PS1 jejunum and 0.85 ± 0.3% for the WT jejunum. A 1.9-fold reduction in the average amount of valsartan permeating the jejunum of APP/PS1 mice relative to that of WT mice was also detected. Although no apparent morphological alterations were observed in the jejunal tissue of APP/PS1 mice, the permeability of 14C-mannitol across the jejunum from APP/PS1 mice was lower than that across the WT jejunum (Papp= 10.7 ± 3.7 × 10-6 and 6.0 ± 3.4 × 10-6 cm/s, respectively), suggesting tightened paracellular junctions in APP/PS1 mice. These studies are the first to demonstrate, in APP/PS1 mice, reduced intestinal permeability and the absorption of drugs commonly prescribed to people with AD for their comorbidities. If these findings translate to people with AD, then modified dosing regimens may be necessary for selected drugs to ensure that their plasma concentrations remain in the effective range.

Efflux transporters and tight junction expression changes in human gastrointestinal cell lines cultured in defined medium vs serum supplemented medium.

AIMS: Many gastrointestinal cell lines including Caco-2, LS174T and RKO require foetal calf serum (FCS) in culture medium. However, when isolating secreted product from conditioned medium (CM), after cell exposure to a trigger, it is better to remove FCS in the culture medium for identification of secreted products of interest. However, it is unknown whether defined medium adversely affects active efflux protein expression and tight junction formation. MATERIALS AND METHODS: Using different gastrointestinal cell lines chosen with different levels of efflux transporter expression, fully defined components, such as using transferrin, insulin, selenium and ethanolamine without FCS or with a reduced percentage of FCS (2%) were tested as an optimal choice for cell growth. In addition to morphological characteristics, the expression of the ABC efflux transporters, ABCB1 (P-glycoprotein [P-gp]), ABCC2 (multidrug resistance associated protein 2), ABCG2 (breast cancer resistance protein) and occludin was determined. KEY FINDINGS: The cells required a minimum of 2% FCS for expression of transporters. Fully defined medium with no serum adversely affected the expression of transporters, especially P-gp. An important characteristic of Caco-2 cells is its ability to form tight junctions. Caco-2 did not form adequate tight junctions without 10% FCS added in the medium, as evidenced by low TEER values and reduced occluding immunohistochemistry. SIGNIFICANCE: FCS is required for efflux protein expression and tight junction generation. Nevertheless, it is possible to use 5 fold less FCS which assists with low molecular weight secretion isolation. Passage number also contributes significantly to the presence of these transporters.

Anti-mumps virus activity by extracts of Mimosa pudica, a unique Indian medicinal plant.

Mumps is an acute and self-limiting disease characterized by parotitis, however in some cases it leads to aseptic meningitis, deafness, encephalitis and orchitis, which is a serious health concern. MMR vaccination was successful in eradicating the disease however, recent reports question the efficacy of MMR vaccine and countless outbreaks are observed in vaccinated populations throughout the world. Lack of specific treatment methods for mumps infection and inefficiency of MMR vaccine in vaccinated populations accentuates the need for the development of novel drugs to control mumps virus mediated serious infections. It was with this backdrop of information that the anti-mumps virus activity of Mimosa pudica was evaluated. Suspected mumps cases were collected to isolate a standard mumps virus by systematic laboratory testing which included IgM antibody assays, virus isolation, RT-PCR and phylogenetic analysis. The virus was quantified by TCID50 assay and anti-mumps virus property was evaluated by CPE reduction assay and cytotoxicity of the extract was measured by MTT assay and phytochemical analysis was done by gas chromatography-mass spectroscopy. The RT-PCR and phylogenetic tree analysis of the SH gene sequence of the clinical isolate showed it to be mumps virus genotype C. 150 µg/ml concentration of M. pudica completely inhibited mumps virus and the drug was found to be non-toxic up to 2 mg/ml. M. pudica was thus found to be a potent inhibitor of MuV.