A partir de paramètres électriques comme le courant de court-circuit, la tension transépithéliale et la conductance, il est possible d'étudier des phénomènes de transports électrogéniques à travers un tissu biologique. Ces mesures peuvent contribuer à l’étude d’une molécule en fonction de sa traversée et de son action sur les propriétés de l’épithélium, de son mécanisme de transport, de sa relation concentration-passage ou encore de ses effets comparés à des molécules de référence. Le travail réalisé porte sur la conception d’un système automatisé permettant de mesurer ces trois paramètres électriques. Le principe de base utilisé est celui de la chambre d’Ussing. Il consiste à monter un tissu biologique entre deux demi-chambres pour isoler ses cotés muqueux et séreux et à mesurer ses paramètres électriques par l’intermédiaire d’électrodes de courant et de référence. L’étude a abouti à la réalisation d’une chambre d’Ussing modifiée pour optimiser la circulation de la solution physiologique et homogénéiser la densité de courant électrique traversant le tissu biologique. Des électrodes en acier inoxydable ont également été étudiées pour démontrer leur utilisation possible dans la chambre. Le principe de mesure retenu est fondé sur un correcteur défini d’après une fonction de transfert simplifiée du système. Une modélisation plus précise des interfaces et de différents tissus a été réalisée par impédancemétrie et a été utilisée pour la simulation et la calibration du correcteur. Les résultats obtenus ont été confrontés à un système de référence et permettent d’envisager par la méthode proposée une utilisation améliorée des chambres d’Ussing. / With electrical parameters such as the short circuit current, the transepithelial voltage and the conductance it is possible to study electrogenic transport across biological barriers. These measurements can be useful for the study of a molecule on the basis of its crossing behavior and its action on the epithelium properties, its dose effect relationship and its comparison with known molecules. The purpose of this work was to achieve an automated device which can measure these three electrical parameters. The used measurement principle is based on the Ussing’s chamber. This principle consists in mounting a biological tissue between two half chambers in order to isolate its mucosal side from its serous side and to measure its electrical parameters using working electrodes and reference electrodes. The study led to the design of a modified Ussing’s chamber which improves the fluid flow and the electric current density through the biological tissue. Stainless steel electrodes have been also studied in order to demonstrate their potential use in the chamber. The measurement principle is based on a controller synthesized from a simplified transfer function model. A more accurate model of the interfaces with various tissues was carried out by impedance spectroscopy and was used for the controller’s simulation and calibration. The results were checked with a reference system and allow to consider the proposed method as an improvement of the Ussing’s chamber.

La connaissance des modalités d’absorption trans-épithéliale des molécules actives est un préalable indispensable à leur formulation rationnelle. Parmi les diverses méthodes in vitro disponibles, la technique de la chambre de perméation d’Ussing se distingue non seulement par une relative facilité de mise en œuvre, mais surtout la possibilité de déterminer de manière fiable les modalités de passage des molécules d'intérêt au travers de l'épithélium digestif (transport actif/passif, voies paracellulaire/transcellulaire, transports d’efflux, effets du métabolisme), ainsi que les caractéristiques électrophysiologiques et la viabilité du tissu.Nous présentons tout d'abord les principes généraux de la technique, les paramètres électriques utilisés en vue de l’interprétation des données physiologiques. Enfin, nous proposons une méthodologie pour l'évaluation du passage transmembranaire des molécules actives.La partie expérimentale du travail a eu pour objectif d'évaluer l'apport de cette approche du modèle lorsqu'il s'agit de mesurer l'impact des formulations des molécules d'intérêt (solutions, ou dispersions colloïdales) sur le flux d'absorption. Ainsi, dans un premier temps nous avons démontré pour deux molécules modèles, le paracétamol et la vitamine C, que la nature des solutions physiologiques mises en œuvre pouvaient avoir un effet important sur le fonctionnement électrophysiologique de la membrane, en modifiant notamment sa conductance, son intégrité et par voie de conséquence modifiant profondément la perméabilité transépithéliale. Dans un second temps, dans le cadre de travaux menés en collaboration, nous avons utilisé le modèle d’Ussing pour caractériser l'absorption des molécules d'intérêt lorsque celles-ci sont préalablement associées à divers systèmes colloïdaux. D'une part, nous avons ainsi montré que l'association du resvératrol, une molécule très hydrophobe, à des microémulsions permettait d'augmenter d'un facteur x6 à x11 le passage du transresvératrol par rapport au resvératrol natif. D'autre part, nous avons également montré que l'association d'une héparine de bas poids moléculaire, très hydrophile et naturellement très peu absorbée, mais associée à des nanoparticules de squalène permettait d’augmenter considérablement le flux d'absorption. En conclusion, l'ensemble de nos travaux montre l'intérêt du modèle d’Ussing lorsqu'on souhaite détailler les mécanismes physico-chimiques et biologiques par lesquels les nanoparticules sont susceptibles d'améliorer le passage digestif de molécules naturellement mal absorbées / One has to have the knowledge of the transepithelial absorption method for active molecules, as it is a necessity for rational formulation. Among various in vitro methods, the Ussing chamber technique stands out not only by its relative ease to implement, but mostly through the practical arrangements of the molecules through the digestive epithelium (active/passive transport, paracellular/transcellular, transport efflux, metabolic effects) and electrophysiological characteristics and viability of the tissue.Firstly, we will present the general principles of the technique, the electrical parameters used for the interpretation of physiological data. Eventually, we will suggest a methodology for evaluating the transmembrane passage of active molecules.The experimental part of the work is aimed to evaluate the contribution of this model approach when it comes to measuring the impact of the formulations of molecules (solutions or colloidal dispersions) on the flow of absorption.So initially we worked around with two molecule models, paracetamol and vitamin C, as the nature of physiological solutions implemented could have a significant effect on the electrophysiological function of the membrane, it could change its conductance, and therefore change its transepithelial permeability.Secondly, concerning the collaborative work, we used the Ussing model to characterize the absorption of molecules when they were previously associated with various colloidal systems. On the one hand, we have shown that the combination of resveratrol, a very hydrophobic molecule, has microemulsions which allow an increase by a factor from x6 to x11, the passage of transresveratrol compared to native resveratrol. Additionally, we also showed that the combination of heparin, a lower molecular weight, extremely hydrophilic and poorly absorbed, but when associated with squalene nanoparticles, makes it possible to significantly increase the absorption flow.As a conclusion, all our work shows through Ussing chamber model, that when one wants to detail the physico-chemical and biological mechanisms, the nanoparticles can indeed improve the digestive passage, for those molecules which are poorly absorbed naturally.

Ruminal acidosis is a persisting digestive disorder in modern ruminant production; however, the susceptibility of cows to ruminal acidosis differs among cows fed a common diet. The overall objective of this research was to evaluate factors affecting the susceptibility of cows to ruminal acidosis. This research demonstrated that feeding sucrose in replacement for corn grain to Holstein cows in early lactation does not increase the risk for ruminal acidosis and may actually increase ruminal pH. However, regardless of dietary treatment, cows in early lactation were at risk for ruminal acidosis. In Study 2, diets differing in the forage-to-concentrate ratio were fed to Holstein cows to evaluate changes in the in vivo rate of short-chain fatty acid absorption (SCFA) and the expression of genes coding for transporters and enzymes involved in the absorption and metabolism of SCFA in ruminal tissue. Contrary to the hypothesis, the fractional rate of absorption and expression of genes involved in SCFA absorption and metabolism were not affected by the forage-to-concentrate ratio. Considerable variation among individual cows for the severity of ruminal acidosis was detected for cows on the diet containing the low forage-to-concentrate ratio. To determine the cause of this variation, a ruminal pH measurement system was developed to accurately and precisely measure ruminal pH in non-cannulated small ruminants. Sheep were then subjected to a ruminal acidosis challenge model in vivo, and the absorption of acetate and butyrate across the isolated ruminal epithelia was measured in vitro in Ussing chambers. The results of this study demonstrated that differences in the severity of ruminal pH depression among animals could largely iv be accounted for by differences in the absorptive capability of the ruminal epithelium. In summary, although ruminal acidosis is a common digestive disorder in dairy production systems, variation in the susceptibility to ruminal acidosis is common. The cause for much of this variation is due to differences in the absorptive capacity of the ruminal epithelia. / Animal Science

Short chain fatty acids (SCFA) synthesized in the rumen from carbohydrate fermentation are an essential energy source for ruminants. Current literature supports that SCFA are absorbed across the rumen epithelium via passive diffusion or protein-mediated transport, however, the rate and degree to which these pathways adapt to a change in diet fermentability is unknown. Furthermore, Na+ flux is partially determined by SCFA absorption, and thus is a key indicator of functional changes in the rumen epithelium. The objectives of this study were to determine the time required for a change in SCFA and Na+ absorption across the bovine rumen epithelium and to evaluate the rate and degree to which absorption pathways adapt to an increase in diet fermentability relative to changes in surface area. Twenty-five weaned Holstein steer calves were blocked by body weight and randomly assigned to either the control diet (CON; 91.5% hay and 8.5% vitamin/mineral supplement) or a moderately fermentable diet (50% hay; 41.5% barley grain, and 8.5% vitamin/mineral supplement) fed for 3 (G3), 7 (G7), 14 (G14), or 21 d (G21). All calves were fed at 2.25% BW at 0800 h. Reticular pH was recorded every 5 min for 48 h prior to killing (1000 h). Ruminal tissue was collected for Ussing chamber, barrier function, surface area measurements, and gene expression. Net 22Na+ flux (JNET-Na; 80 kBq/15 mL), the rate and pathway of mucosal to serosal 3H-acetate (JMS-acetate; 37 kBq/15 mL) and 14C-butyrate (JMS-butyrate; 74 kBq/15 mL) flux, and serosal to mucosal flux of 3H-mannitol (JSM-mannitol; 74 KBq/15 mL) and tissue conductance were measured. Half of the chambers assigned to measure JMS-acetate and JMS-butyrate were further assigned to 1 of 2 acetate and butyrate concentration treatments: 10 mM (Low) and 50 mM (High). Furthermore, JSM-mannitol flux was also measured during an acidotic and hyperosmotic challenge (CHAL) and recovery (REC) to measure barrier function of ruminal tissue. Mean reticular pH, which was positively correlated with ruminal pH (R2 = 0.5477), decreased from 6.90 for CON to 6.59 for G7 then increased. Net Na+ flux increased 125% within 7 d. Total JMS-acetate and JMS-butyrate increased from CON to G21, where passive diffusion was the primary SCFA absorption pathway. Total JMS-acetate and JMS-butyrate were greater when incubated in High vs. Low. Effective surface area of the ruminal epithelium was not affected by dietary treatment. Increased JSM-mannitol, tissue conductance, and increased expression of IL-1β and TLR2 (tendencies) with increased days fed the moderate grain diet indicated reduced rumen epithelium barrier function. Furthermore, the CHAL treatment reduced barrier function, which was not reversible during REC. This study indicates that a moderate increase in diet fermentability increases rumen epithelium absorptive function in the absence of increased SA, but reduces barrier function. Data from this study also suggests that absorption and barrier function follow different timelines, posing a challenge for ruminant diet adaptation to moderately to highly fermentable diets.

No description available.

Background: Several environmental risk factors have been implicated in the pathogenesis ofinflammatory bowel disease (IBD) and might cause an altered barrier function, a hallmark ofIBD. Recent evidence suggests that patients with late-onset ulcerative colitis (UC) have anincreased serum level of perfluoroalkyl substances (PFAS), one of the major chemical groupscontaminating our diet. A potential route via which PFAS might contribute to the disease is bydisrupting the intestinal barrier. However, whether intake of PFAS dose induce an increasedintestinal permeability is still unknown. Aim: The aim of the thesis is to investigate the effect of in vivo exposure toperfluorooctanesulfonic acid (PFOA) in mice on colon barrier function. The hypothesis is thatlong time exposure to PFOA contributes to the development of late-onset ulcerative colitis bydisrupting the intestinal barrier. Methods: This controlled laboratory study used 7 mice exposed to PFOA in vivo via thedrinking water for 3 weeks and a control group of 9 mice for reference. Colon tissue from themice were excised for assessing intestinal permeability using the Ussing chamber method.FITCH-dextran was used as a macromolecular probe in the Ussing chamber to investigate themucosal-serosal flux across the intestinal mucosa to see macromolecular permeability andelectrophysiological parameters were assessed to investigate tight junction permeability,stimulated secretory response to Carbachol and active ion transport. Results: Although there were no statistically significant results between the PFOA treated groupand the control group, a trend of increased secretory response to Carbachol was observed in thePFOA group compared to the controls. Conclusion: The study demonstrates that in vivo exposure to PFOA does not induce an alteredintestinal barrier in terms of electrophysiological parameters and macromolecular flux. Futureexperiments are needed with a larger population and potentially genetically predisposed mice.Key

Le mitotane ou o,p'-DDD est un dérivé organochloré très peu soluble dans l'eau. Il est utilisé dans le traitement du cancer corticosurrénalien métastasé ou inopérable (Lysodren®). En thérapeutique, il est nécessaire d'utiliser de fortes doses pour atteindre généralement au bout de trois mois, la mitotanémie efficace. Cela entraine le plus souvent, des effets indésirables gastroduodénaux et neuromusculaires, qui rendent les patients très peu compliants.L'objectif principal de cette thèse est de mettre au point, d'évaluer et de comparer les différentes formulations de mitotane afin d'améliorer la biodisponibilité du mitotane par rapport à la forme conventionnelle Lysodren®. Dans cette optique, le but recherché en clinique humaine serait de concevoir une forme galénique pouvant permettre d'utiliser de faibles doses journalières afin d'éviter les effets indésirables liés à la toxicité cumulative du mitotane. Pour cela, dans le but d'augmenter sa solubilité et de le rendre plus biodisponible, nous avons encapsulé le mitotane sous formes de particules polymériques et de microémulsions.Nous avons préparé des nanocapsules à partir de polymères biodégradables (la poly-epsilon-caprolactone) (PCL) et d'une association de PCL et de polymères non biodégradables (L'Eudragit® RL). Nous avons également préparé des microparticules de PCL et des systèmes autoémulsionnants ou SMEDDS.L'évaluation des caractéristiques physico-chimiques des particules montre des diamètres de 300 nm pour les nanocapsules et pour les microparticules, des diamètres variant de 40 à 76 µm. Le potentiel zêta est négatif pour les particules de PCL et positif pour celles associant les polymères PCL et RL. Pour les microémulsions, les diagrammes pseudoternaires ont permis le choix d'une association comportant du Capryol®, Tween® 20 et Crémophor® EL (33, 33, 33%). Les microémulsions ont un diamètre d'environ 40 nm. Les profils de libération in vitro du mitotane montrent une cinétique rapide et une quantité de mitotane libérée plus importante pour les microémulsions et les formes particulaires par rapport à la forme conventionnelle Lysodren®.De même, la réalisation de la pharmacocinétique à dose unique de 100 mg/kg chez des lapins montre des biodisponibilités relatives de 339% plus importantes pour les microémulsions, 195% pour les nanocapsules et 187% pour les microparticules. La quantification du mitotane absorbé dans des modèles Caco-2 montre une absorption complète du mitotane au bout de 4h lorsque le mitotane est formulé sous forme de microémulsions. Pour les microparticules et les nanocapsules, 50 et 45% de la dose initiale ont été respectivement absorbées par les cellules Caco-2. Cette évaluation sur le modèle Caco-2 a également confirmé le faible taux de passage de la poudre de mitotane (10%). Enfin, la réalisation des études de passage sur des coupes de jéjunum de rat en chambre de Ussing confirme que la quantité de mitotane qui a diffusé à travers la membrane jéjunale à partir des microémulsions est 5 fois supérieure à celle obtenue à partir de la poudre de mitotane.En conclusion, les microémulsions présentent un intérêt comme forme orale pour améliorer la biodisponibilité du mitotane. Elles ont pour avantage de multiplier la biodisponibilité par un facteur 3 chez le lapin et sont de fabrication peu coûteuse. Elles constituent une réelle alternative à la forme conventionnelle Lysodren® disponible actuellement sur le marché européen / Mitotane or o, p'-DDD is a organochlorine drug, very slightly soluble in water. It is used in the treatment of non resectable and metastasized adrenocortical carcinoma (Lysodren®). In therapy, to achieve therapeutic plasma level, high cumulative doses of mitotane were usually used during 3-5 months. This regimen causes gastrointestinal and neuromuscular side effects and make patients to be less compliants.The main objective of this work is to developp differents formulations of mitotane in order to improve the relative bioavailability when compared with conventional form Lysodren®. To shorten this equilibration time and reduce side effects, it's necessary to develop a new formulation. In order to increase mitotane solubility and make it more bioavailable, we encapsulated mitotane in polymeric particles and microemulsions.We prepared nanocapsules with biodegradable polymers (poly-epsilon-caprolactone) (PCL) and an association of PCL and non-biodegradable polymers (Eudragit®RL). We have also prepared PCL microparticles and a Self Microemulsifying Drug Delivery System or SMEDDS.Nanocapsules and microparticles diameters were respectively 300 nm and 40 to 76 µm. The zeta potential is negative for PCL particles wheras particles combining PCL and Eudragit®RL polymers exhibited positive zêta potential. For microemulsions, we investigated by constructing ternary phase diagrams and choosing the optimal formulation consisted of a mixture of Capryol®, Tween® 20 and Cremophor® EL (33, 33, 33%) with an emulsion diameter of 40 nm. The release of mitotane from SMEDDS and particles was higher and faster than from the conventional form Lysodren®.Pharmacokinetics after single-dose of oral mitotane formulations (100 mg/kg) in rabbits showed a 339% increase of relative bioavailability with microemulsions, 195% with the nanocapsules and 187% with the microparticles. Caco-2 cell culture showed a complete absorption of mitotane after 4h with microemulsions. For microparticles and nanocapsules, 50 and 45% of the initial dose, were respectively absorbed by Caco-2 cells. Caco-2 cells evaluation confirmed the low absorption of the mitotane powder (10%). Finally, Ussing chamber showed that microemulsions pass through the intestinal barrier 5 times higher than a solution of mitotane. In conclusion, microemulsions showed improvement of bioavailability of mitotane by a factor 3 in rabbits and could allow cost effective production. Microemulsions are a real alternative to Lysodren® which is currently available on the European market

L'objectif de cette thèse était de développer de nouveaux « donneurs de NO » stables en liant du S-nitrosoglutathion (GSNO) à une structure polymérique. Dans une première étape, les polymères ont été liés au glutathion (GSH) : le chitosan-GSH et l'alginate-GSH ont ainsi été préparés par la « méthode des carbodiimides » et dans une deuxième étape, les polymères finaux [SNOC (S-nitrosoglutathione-oligosaccharide-chitosan) et SNA (S-nitrosoglutathione-alginate)] ont été préparés par nitrosation des deux conjugués précédent. La quantité de NO fixée a été déterminée par les méthodes Griess et Saville. L’aptitude des polymères à libérer du NO et à passer la barrière intestinale [SNOC et SNA] a été évaluée dans une chambre d’Ussing. Nous avons obtenu des polymères avec des quantités variables de NO en fonction de la méthode utilisée (159 µmol de NO/g à 525 µmol de NO/g pour le SNOC ; 174 µmol de NO/g à 468 µmol de NO/g pour le SNA). Le SNOC était stable pendant au moins 6h et le SNA pendant au moins 10h. Enfin, nous avons essayé de mettre au point des microparticules de GSH et GSNO par spray drying avec de l’Eudragit ® FS 30D gastro-résistant. La caractérisation des microparticules a été réalisée par microscopie électronique à balayage (SEM), par diffraction X (PXRD) et par spectroscopie infrarouge (FTIR). Les essais de libération in vitro ont été réalisés dans un tampon (pH 1,2, 3, 6, 6,8 et 7,4). Les microparticules étaient chargées négativement avec une taille moyenne allant de 5 à 7 µm. La formulation était stable à pH acide mais a montré une libération rapide à pH basique ; elle pourrait donc servir de système de délivrance du NO au niveau intestinal. / The aim of the thesis was to develop novel and stable NO-donors by linking S-nitrosoglutathione (GSNO) to a polymer backbone. In the first step, chitosan-GSH and alginate-GSH conjugates were prepared by a carbodiimide reaction and in the second step SNOC (S-nitrosoglutathione-oligosaccharide-chitosan) and SNA (S-nitrosoglutathione-alginate) were prepared by the nitrosation of both conjugates respectively. The amount of NO was determined by Griess and Saville methods. Stability and ex vivo experiments of SNOC and SNA were performed in an Ussing chamber through rat intestine. We obtained polymers with different amount of NO (i.e. 159 µmol of NO/g to 525 µmol of NO/g for SNOC; 174 µmol of NO/g to 468 µmol of NO/g for SNA) depending upon the procedure of nitrosation. SNOC was stable for at least 6h and SNA for at least 10h. Also, we aimed to develop spray dried microparticles of GSH and GSNO based on Eudragit® FS 30D polymer. The microparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (PXRD), infrared spectroscopy (FTIR) and in vitro release studies were performed in different pH conditions (pH 1.2, 3, 6, 6.8 and 7.4). The microparticles were negatively charged with mean particle size ranging from 5 to 7 µm. The formulation was stable and was resistant to acidic pH but showed rapid release in basic pH; hence, they can be used as colon specific drug delivery systems for the treatment of Crohn’s disease. We think that these formulations could be used in animal models in the treatment of Crohn’s disease.

<p>Polyacryl starch microparticles have been developed as a new mucosal vaccine adjuvant intended for use in oral vaccination. The main objectives of this thesis were to evaluate the efficacy of these polyacryl starch microparticles and to study their uptake through mucosal tissues. Secreted or surface components of <i>Salmonella enterica</i> serovar Enteritidis were used in free form or were conjugated to or mixed with the microparticles in vaccination studies in mice in order to find components suitable for use in a future combination vaccine against enteric bacteria such as enterotoxigenic <i>Escherichia coli</i>.</p><p>The immune response elicited using secreted proteins from <i>S. enterica</i> serovar Enteritidis was shown to be mainly directed against flagella-related antigens and partly by LPS. Flagellin was purified and used in C3H/HeJ mice that do not respond to LPS. Strong immune responses were observed even when the flagellin was given orally alone. Recombinant <i>Salmonella</i> atypical fimbriae (SafB/D) complexes, a conserved structure within <i>Salmonella</i> species, were also studied and shown to be immunogenic after administration both subcutaneously and nasally, but not orally. Oral challenge using live bacteria, showed that mice orally immunised with the secreted antigens, resulted in a lower degree of infection than that seen in non-vaccinated mice. Similarly, mice that had been immunised with purified free flagellin had a lower degree of infection than untreated mice. However, with mice, immunised with SafB/D complexes plus rCTB, only the subcutaneous route resulted in a lower degree of infection than seen in untreated mice. The polyacryl starch microparticles were effective as an adjuvant with secreted proteins, but did not potentiate the immune response in the study using flagellin. </p><p>Confocal laser-scanning and transmission electron microscopy demonstrated that the microparticles were taken up by pig respiratory nasal mucosa mounted in horizontal Ussing chambers. Although anticytokeratin 18 stained mucus-producing cells, M cells were not seen in the studied area. </p><p>Changing the route of administration of the microparticles conjugated with serum albumin can cause differences in the IgG-subclass ratios. The mucosal immune response measured as specific s-IgA levels, was induced by oral but not parenteral immunisation.</p>

A. A study of Stichodactyla helianthus toxin’s potential to penetrate the buccal mucosa Introduction:  Buccal mucosa is an alternative route for drug administration and has advantages over other conventional routes by avoiding both enzymes in the gastro intestinal system and the hepatic first passage mechanism. Stichodactyla helianthus toxin (ShK) is a peptide toxin that blocks potassium channels in T lymphocytes and could be a future treatment for autoimmune diseases when finding a suitable way of administration. Aim:  The purpose of this part of the study was to develop a robust and reproducible assay for identification and quantification of ShK. The method was then employed for a proof of principle study; determining the concentration of ShK following an in vitro permeability experiment, to evaluate the potential of ShK penetrating the buccal mucosa in porcine tissue.  Materials and Methods:  An HPLC method was developed and validated. A piece of porcine buccal mucosa was used as a membrane because of its similarities with human buccal mucosa, and cinched in between a modified Ussing Chamber consisting of a donor and a receptor chamber. Samples were withdrawn from the receptor chamber to determine the amount of ShK that had penetrated the membrane. Results: The HPLC method developed for quantification of ShK demonstrated high accuracy and precision. No concentrations of ShK were able to be quantified from the receptor chambers. Conclusions:  A robust assay for quantification of ShK was developed but the results from the experiment indicated that ShK could not penetrate the buccal mucosa membrane. B. An investigation of the permeability alterations in the blood-brain barrier associated with Alzheimer’s disease   Introduction:  The blood brain barrier (BBB) protects the brain from potential dangerous substances by different barrier properties such as tight junctions and efflux transporters such as P-glycoprotein. Previous studies have showed that the barrier functions may be altered in Alzheimer’s disease and thereby increase the exposure to substances that are normally excluded from the brain parenchyma. This could be an issue regarding safety and toxicity of medications used among Alzheimer patients. Aim:  The aim of this part of the study was to investigate the difference in brain uptake of verapamil, digoxin, loperamide, propanolol, diazepam and sucrose between 3xTg-AD mice and wild type control mice. Materials and Methods: Female 3xTg-AD mice and control mice of the age 11.5-13.5 months were used. In Situ brain perfusion with radiolabeled substances (n=5-12) was performed and the brain uptake ratio of the substances was compared and statistically analyzed.  Results: No difference in the vascular volume was found when comparing 3xTg-AD with control mice. The ratio of diazepam was observed to be higher in the cortex and propranolol higher in the hippocampus, of 3xTg-AD mice. The uptake ratio of verapamil was higher in both the hippocampus and cortex of 3xTg-AD mice whereas digoxin appeared to be lower in the cortex of 3xTg-AD mice. There was no difference in uptake ratio of loperamide between 3xTg-AD and control mice. Conclusions:  This study in addition to previously executed studies in our laboratory, showed that the membrane thickness is age dependent in 3xTg-AD and that further studies needs to be conducted on the expression of P-glycoprotein in the BBB in 3xTg-AD and control mice.