Brain Barrier In Mice Research Articles

Walnut-derived peptides cross the blood–brain barrier and ameliorate Aβ-induced hypersynchronous neural network activity

Walnut peptides exhibit promising neuroprotective effects; however, they must be absorbed in their intact form through the gastrointestinal tract into the bloodstream and brain. In this study, the effects of the walnut peptide TWLPLPR (TW-7) were evaluated in mice, including its absorption and distribution ability to cross the blood–brain barrier, and inhibitory effects on hyperactivity of primary hippocampal neurons. TW-7 was stable in plasma, and the peptide retention rate was 88.19 ± 0.70 % after 48 h. In vitro imaging indicated that TW-7 was distributed in the brain, liver, lungs, and kidneys of mice after gavage, and an immunofluorescence analysis indicated that TW-7 could accumulate in mouse brain parenchyma; in addition, TW-7 reached its maximum concentration (5.36 ± 1.59 µg/mL) in plasma 2 h after gavage, and reached its peak concentration (0.95 ± 0.19 µg/g) in brain tissue 4 h after gavage. Microelectrode array and immunofluorescence analyses confirmed that TW-7 ameliorates the overexcitation of primary hippocampal neurons induced by Aβ25–35 through inhibiting the excessive release of glutamate and protecting synaptic structure and function. These results suggest that TW-7 can penetrate the blood–brain barrier in mice and positively affect the electrophysiological activity of neurons. More broadly, these findings provide a theoretical basis for the development and application of walnut peptide-based functional food for Alzheimer’s disease intervention.

A novel determination method of quaternary ammonium oxime reactivators and their blood–brain barrier permeability evaluation by surface‐enhanced Raman spectrometry

The quaternary ammonium oxime reactivators are a class of important reactivators for nerve agents poisoning, and their sensitive and specific analysis in biomedical samples meets many challenges due to their highly polar properties. In present paper, a novel determination method based on surface-enhanced Raman spectrometry (SERS) was developed for series of quaternary ammonium oxime reactivators. The self-cleaning effect of iodine anion on the surface of porous shell-insulated nanoparticles and the electrostatic adsorption effect were proved to be effective to remove the strong interference of protein and other coexisting substances, significantly improve the response intensity and fingerprint feature of Raman peaks. The analysis of five important quaternary ammonium oxime reactivators (PAM-Cl, TMB-4, MMB-4, HI-6, LüH6) was achieved in biomedical samples, which had the merit of simple sample pretreatment, rapid speed, high sensitivity and fingerprint peak characteristics. The detection limits reached values of as low as 0.5 ng·ml-1 for dipyridyl quaternary ammonium oxime reactivators. The method has been successfully used for blood concentration monitoring in vivo and evaluation of the liposomes drug delivery ability to penetrate the blood-brain barrier in mice.

A Novel Oral Arginase 1/2 Inhibitor Enhances the Antitumor Effect of PD-1 Inhibition in Murine Experimental Gliomas by Altering the Immunosuppressive Environment.

Glioblastomas (GBM) are the common and aggressive primary brain tumors that are incurable by conventional therapies. Immunotherapy with immune checkpoint inhibitors is not effective in GBM patients due to the highly immunosuppressive tumor microenvironment (TME) restraining the infiltration and activation of cytotoxic T cells. Clinical and experimental studies showed the upregulation of expression of the arginase 1 and 2 (ARG1 and ARG2, respectively) in murine and human GBMs. The elevated arginase activity leads to the depletion of L-arginine, an amino-acid required for the proliferation of T lymphocytes and natural killer cells. Inhibition of ARG1/2 in the TME may unblock T cell proliferation and activate effective antitumor responses. To explore the antitumor potential of ARG1/2 inhibition, we analyzed bulk and single-cell RNA sequencing (scRNA-seq) data from human and murine gliomas. We found the upregulation of ARG1/2 expression in GBMs, both in tumor cells and in tumor infiltrating microglia and monocytes/macrophages. We employed selective arginase inhibitors to evaluate if ARG1/2 inhibition in vitro and in vivo exerts the antitumor effects. A novel, selective ARG1/2 inhibitor - OAT-1746 blocked microglia-dependent invasion of U87-MG and LN18 glioma cells in a Matrigel invasion assay better than reference compounds, without affecting the cell viability. OAT-1746 effectively crossed the blood brain barrier in mice and increased arginine levels in the brains of GL261 glioma bearing mice. We evaluated its antitumor efficacy against GL261 intracranial gliomas as a monotherapy and in combination with the PD-1 inhibition. The oral treatment with OAT-1746 did not affect the immune composition of TME, it induced profound transcriptomic changes in CD11b+ cells immunosorted from tumor-bearing brains as demonstrated by RNA sequencing analyses. Treatment with OAT-1746 modified the TME resulting in reduced glioma growth and increased antitumor effects of the anti-PD-1 antibody. Our findings provide the evidence that inhibition of ARG1/2 activity in tumor cells and myeloid cells in the TME unblocks antitumor responses in myeloid cells and NK cells, and improves the efficacy of the PD-1 inhibition.

The S1 protein of SARS-CoV-2 crosses the blood-brain barrier in mice.

It is unclear whether SARS-CoV-2, which causes COVID-19, can enter the brain. SARS-CoV-2 binds to cells via the S1 subunit of its spike protein. We show that intravenously injected radioiodinated S1 (I-S1) readily crossed the blood-brain barrier (BBB) in male mice, was taken up by brain regions and entered the parenchymal brain space. I-S1 was also taken up by lung, spleen, kidney, and liver. Intranasally administered I-S1 also entered the brain, though at ~10 times lower levels than after intravenous administration. APOE genotype and sex did not affect whole-brain I-S1 uptake, but had variable effects on uptake by the olfactory bulb, liver, spleen, and kidney. I-S1 uptake in the hippocampus and olfactory bulb was reduced by lipopolysaccharide-induced inflammation. Mechanistic studies indicated that I-S1 crosses the BBB by adsorptive transcytosis, and that murine angiotensin-converting enzyme-2 is involved in brain and lung uptake, but not in kidney, liver, or spleen uptake.

New imidazopyridines with phosphodiesterase 4 and 7 inhibitory activity and their efficacy in animal models of inflammatory and autoimmune diseases.

Herein, we describe the rapid synthesis of a focused library of trisubstituted imidazo[4,5-b]pyridines and imidazo[4,5-c]pyridines from 2,4-dichloro-3-nitropyridine using the combination of solution-phase/solid-phase chemistry as new potential anti-inflammatory agents in the treatment of autoimmune diseases. Structure-activity relationship studies, followed by the structure optimization, provided hit compounds (17 and 28) which inhibited phosphodiesterase 4 (PDE4) with IC50 values comparable to rolipram and displayed different inhibitory potency against phosphodiesterase 7 (PDE7). Among them, compound 17 showed a beneficial effect in all the studied animal models of inflammatory and autoimmune diseases (concanavalin A-induced hepatitis, lipopolysaccharide-induced endotoxemia, collagen-induced arthritis, and MOG35-55-induced encephalomyelitis). In addition, compound 17 showed a favorable pharmacokinetic profile after intraperitoneal administration; it was characterized by a fast absorption from the peritoneal cavity and a relatively long terminal half-life in rats. It was found to penetrate brain barrier in mice. The performed experiments sheds light on the impact of PDE7A inhibition for the efficacy of PDE4 inhibitors in these disease conditions.

XQ-1H regulates Wnt/GSK3β/β-catenin pathway and ameliorates the integrity of blood brain barrier in mice with acute ischemic stroke

10-O-(N, N-dimethylaminoethyl) ginkgolide B methanesulfonate (XQ-1H), a novel analog of ginkgolide B, has been preliminarily recognized to show bioactivities against ischemia-induced injury. However, the underlying mechanism still remains to be fully elucidated. The aim of this study was to investigate the effect of XQ-1H against cerebral ischemia/reperfusion injury (CIRI) from the perspective of blood brain barrier (BBB) protection, and explore whether the underlying mechanism is associated with Wnt/GSK3β/β-catenin signaling pathway activation. The therapeutic effects of XQ-1H were evaluated in mice subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) and in immortalized mouse cerebral endothelial cells (bEnd.3) challenged by oxygen and glucose deprivation/reoxygenation (OGD/R). Results showed that treatment with XQ-1H improved neurological behavior, reduced brain infarction volume, diminished edema, and attenuated the disruption of BBB in vivo. In vitro, XQ-1H increased cell viability and maintained the barrier function of bEnd.3 monolayer after OGD/R. Moreover, the protection of XQ-1H was accompanied with activation of Wnt/GSK3β/β-catenin pathway and upregulation of tight junction proteins. Notably, the protection of XQ-1H was abolished by Wnt/GSK3β/β-catenin inhibitor XAV939 or β-catenin siRNA, indicating XQ-1H exerted protection in a Wnt/GSK3β/β-catenin dependent profile. In summary, XQ-1H attenuated brain injury and maintained BBB integrity after CIRI, and the possible underlying mechanism may be related to the activation of Wnt/GSK3β/β-catenin pathway and upregulation of tight junction proteins.

Striatal Acetylcholine Helps to Preserve Functional Outcomes in a Mouse Model of Stroke

Acetylcholine (ACh) has been suggested to facilitate plasticity and improve functional recovery after different types of brain lesions. Interestingly, numerous studies have shown that striatal cholinergic interneurons are relatively resistant to acute ischemic insults, but whether ACh released by these neurons enhances functional recovery after stroke is unknown. We investigated the role of endogenous striatal ACh in stroke lesion volume and functional outcomes following middle cerebral artery occlusion to induce focal ischemia in striatum-selective vesicular acetylcholine transporter-deficient mice (stVAChT-KO). As transporter expression is almost completely eliminated in the striatum of stVAChT-KO mice, ACh release is nearly abolished in this area. Conversely, in other brain areas, VAChT expression and ACh release are preserved. Our results demonstrate a larger infarct size after ischemic insult in stVAChT-KO mice, with more pronounced functional impairments and increased mortality than in littermate controls. These changes are associated with increased activation of GSK-3, decreased levels of β-catenin, and a higher permeability of the blood–brain barrier in mice with loss of VAChT in striatum neurons. These results support a framework in which endogenous ACh secretion originating from cholinergic interneurons in the striatum helps to protect brain tissue against ischemia-induced damage and facilitates brain recovery by supporting blood–brain barrier function.

Chromogranin A derived peptide CGA47-66 inhibits hyper-permeability of blood brain barrier in mice with sepsis

To explore the effect of chromofungin (CHR), a chromogranin A (CGA) derived peptide CGA47-66, on hyper-permeability of blood brain barrier in septic mice. 120 healthy male C57BL/6 mice were randomly divided into groups, with 12 mice in each group. Seventy-two mice were used for dynamic observation of the contents of water and Evan blue (EB) in brain tissue after being treated with lipopolysaccharide (LPS). Another 48 mice were divided into normal saline control group (NS group), LPS induced sepsis model group (LPS group), low-dose CHR pretreatment group (CL+LPS group), and high-dose CHR pretreatment group (CH+LPS group). The septic model was reproduced by intraperitoneal injection of 10 mg/kg LPS 0.1 mL, and the mice in NS group was given equal volume of normal saline. The mice in CL+LPS group and CH+LPS group were intraperitoneally injected with 15.5 μg/kg and 77.5 μg/kg CHR 10 minutes before LPS injection. Six hours after LPS injection, 4 mL/kg of 2% EB was injected via caudal vein, the contents of water and EB in brain tissue were determined, and EB immune fluorescence in brain tissue was determined to assess the changes in permeability of blood brain barrier. Brain pathology was observed with hematoxylin and eosin (HE) staining. With the extension of time after LPS injection, the contents of water and EB in brain tissue were gradually increased, and the time of difference with statistical significance appeared earlier when compared with that of control group in the contents of water than that in EB contents (3 hours and 6 hours, respectively). The contents of water and EB in brain tissue in LPS group were significantly increased as compared with NS group [water content: (79.77±0.62)% vs. (78.28±0.44)%, P < 0.01; EB content (μg/g): 13.87±4.50 vs. 7.13±1.76, P < 0.05]. CHR pretreatment with either of two dosages could reverse the increase in water and EB contents in brain tissue induced by LPS, and the effect was more significant in CH+LPS group [water content: (78.15±0.73)% vs. (79.77±0.62)%, EB (μg/g): 7.09±2.59 vs. 13.87±4.50, both P < 0.05]. It was shown by EB fluorescence observation that the fluorescence signal displayed only in the meninges in NS group, and EB fluorescence was widely distributed in brain parenchyma in LPS group, indicating that the EB leakage in LPS group was more marked than that of NS group. In CHR pretreatment groups, EB fluorescence was decreased in brain parenchyma, indicating that EB leakage was significantly less marked, while it was more obvious in high dose CHR group. It was shown by HE staining that cerebral blood vessel structure was intact in NS group, and the gap around blood vessel was not significant increased. On the other hand, brain structure in LPS group appeared loose, with widening of small perivascular spaces and obvious edema. Brain edema in CHR pretreatment groups was improved as compared with that of the LPS group, and it was more apparent in high dose CHR group. LPS induced change in blood brain barrier permeability in mice in a time-dependent manner. Exogenous CGA derived peptides CHR can inhibit LPS induced hyper-permeability of blood brain barrier in septic mice, thus reduces brain edema, protects the brain tissue, and the effect is more obvious with a high dose of CHR (77.5 μg/kg).

Elevated permeability of the blood–brain barrier in mice intratracheally administered porcine pancreatic elastase

Chronic obstructive pulmonary disease (COPD) shows progressive, irreversible airflow limitation induced by emphysema and lung inflammation. The aim of the present study was to determine if COPD conditions induce blood–brain barrier (BBB) dysfunction. We found that the intratracheal administration of porcine pancreatic elastase (PPE; 3 U) induced alveolar enlargement, increased neutrophil number in bronchoalveolar lavage fluid, and decreased blood oxygen saturation in mice at 21 days after inhalation. In parallel with these lung damages, BBB permeability to sodium fluorescein and Evans blue albumin was markedly increased. Our findings demonstrate that COPD conditions are associated with risk for BBB impairment.

Nicotine pre-exposure reduces stroke-induced glucose transporter-1 activity at the blood-brain barrier in mice.

BackgroundWith growing electronic cigarette usage in both the smoking and nonsmoking population, rigorous studies are needed to investigate the effects of nicotine on biological systems to determine long-term health consequences. We have previously shown that nicotine exerts specific neurovascular effects that influence blood brain barrier (BBB) function in response to stroke. In this study, we investigated the effects of nicotine on carrier-mediated glucose transport into ischemic brain. Specifically, the present study investigates glucose transporter-1 (GLUT1) function and expression at the BBB in a focal brain ischemia model of mice pre-exposed to nicotine.MethodsNicotine was administrated subcutaneously by osmotic pump at the dose of 4.5 mg/kg/day for 1, 7, or 14 days to reflect the plasma levels seen in smokers. Ischemic-reperfusion (IR) injury was induced by 1 h transient middle cerebral artery occlusion (tMCAO) and 24 h reperfusion. Glucose transport was estimated using an in situ brain perfusion technique with radiolabeled glucose and brain vascular GLUT1 expression was detected with immunofluorescence.ResultsThe nicotine pre-exposure (1, 7 & 14 day) resulted in significant reduction in D-glucose influx rate (Kin) across the BBB, with a 49% reduction in 14 day nicotine-infused animals. We observed a 41% increase in carrier-mediated glucose transport across the BBB in saline-infused tMCAO animals compared to saline-infused sham animals. Interestingly, in the tMCAO group of animals pre-exposed to nicotine for 14 days had significantly attenuated increased glucose transport by 80% and 38% compared to saline-infused tMCAO and sham animals respectively. Furthermore, immunofluorescence studies of GLUT1 protein expression in the brain microvascular endothelium confirmed that GLUT1 was also induced in saline-infused tMCAO animals and this protein expression induction was reduced significantly (P < 0.01) with 14 day nicotine pre-exposure in tMCAO animals.ConclusionsNicotine pre-exposure reduced the IR-enhanced GLUT1 transporter function and expression at the BBB in a focal brain ischemia mouse model. These studies suggest that nicotine exposure prior to stroke could create an enhanced glucose deprived state at the neurovascular unit (NVU) and could provide an additional vulnerability to enhanced stroke injury.

Nanoformulation of antiretroviral drugs enhances their penetration across the blood brain barrier in mice

Eradication of virus by sanctuary sites is a main goal in HIV management. The central nervous system (CNS) is a classic model of sanctuary where viral replication occurs despite a complete viral suppression in peripheral blood. In recent years, nanotechnologies have provided a great promise in the eradication of HIV from the CNS. We hereby demonstrate for the first time that the structurally complex antiretroviral drug enfuvirtide (Enf), which normally is unable to penetrate the cerebrospinal fluid, is allowed to cross the blood brain barrier (BBB) in mice by conjugation with a nanoconstruct. Iron oxide nanoparticles coated with an amphiphilic polymer increase Enf translocation across the BBB in both in vitro and in vivo models. The mechanism involves the uptake of nanoconjugated-Enf in the endothelial cells, the nanocomplex dissociation and the release of the peptide, which is eventually excreted by the cells in the brain parenchyma. From the Clinical EditorDespite the success of cocktail therapy of antiretroviral drugs, the complete eradication of HIV remains elusive, due to existence of viral sanctuary sites. The authors showed in this study that an antiretroviral drug complexed with iron oxide nanoparticles and coated with PMA amphiphilic polymer crosses the blood brain barrier. Furthermore, there was significant anti-viral activity. The results would aid further drug designs to eradicate HIV.

Activation of AMPK improves lipopolysaccharide-induced dysfunction of the blood–brain barrier in mice

Primary objective: Lipopolysaccharide (LPS) is known to alter the integrity of the blood–brain barrier (BBB) in sepsis, although the underlying mechanism remains unknown. The aim of this study was to elucidate the molecular mechanisms underlying disruption of the BBB in LPS-induced sepsis.Research design: Both in vitro and in vivo experiments were designed to test the role of AMP-activated protein kinase (AMPK) in LPS-induced BBB dysfunction.Methods and procedures: Human brain microvascular endothelial cells (HBMECs) were cultured. The protein expressions were detected by western blot. BBB integrity was determined by Evans Blue.Main outcomes and results: LPS (1 μg ml−1) dramatically increased the permeability of the BBB and the ROS productions, as well as reducing the expression levels of occludin and claudin-5 in cultured HBMECs. Inhibition of NAD(P)H oxidase by apocynin or up-regulation of AMPK reversed the LPS-induced abnormities in HBMECs. In LPS-induced sepsis in mice, it was found that LPS dramatically increased NAD(P)H oxidase protein expressions and ROS productions in the brain and disrupted BBB function assayed by Evans blue staining, which were abolished by AICAR treatment.Conclusions: It is concluded that AMPK activation improves the functions of the BBB impaired by LPS through suppression of NAD(P)H oxidase-derived ROS in mice.

Of cytokine receptor scissors, grasping bacterial hands, and movement across the blood-brain barrier.

Of cytokine receptor scissors, grasping bacterial hands, and movement across the blood-brain barrier.

OAT3-Mediated Extrusion of the 99mTc-ECD Metabolite in the Mouse Brain

After administration of the (99m)Tc complex with N,N'-1,2-ethylenediylbis-L-cysteine diethyl ester ((99m)Tc-ECD), a brain perfusion imaging agent, the radioactive metabolite is trapped in primate brain, but not in mouse and rat. Here, we investigate the involvement of metabolite extrusion by organic anion transporter 3 (OAT3), which is highly expressed at the blood-brain barrier in mice, in this species difference. The efflux rate of radioactivity in the cerebrum of Oat3(-/-) mice at later phase was 20% of that of control mice. Thus, organic anion transporters in mouse brain would be involved in the low brain retention of radioactivity after (99m)Tc-ECD administration.

A Long Shot? Could neurodegenerative disease be caused by a cyanobacterial toxin?

A Long Shot? Could neurodegenerative disease be caused by a cyanobacterial toxin?

Effect of Rosiglitazone, a PPAR‐γ Ligand on Haloperidol‐Induced Catalepsy

Rosiglitazone (Ros) is a commonly prescribed insulin-sensitizing drug with a selective agonistic activity on the peroxisome proliferator-activated receptor-gamma (PPAR-γ). Rosiglitazone, currently approved for use in type II diabetes, was recently shown to cross the blood–brain barrier in mice, suggesting that it might be suitable for testing neuroprotective effects of PPAR-γ agonists in the CNS. Moreover, the presence of PPAR-γ has been detected both in neuronal and glial cells 1. By binding to DNA on promoter regions, PPAR-γ can regulate the expression of several genes, including inflammatory cytokines, TNF-α, COX, iNOS. Furthermore, Ros attenuated the striatal dopaminergic neurodegeneration by anti-inflammatory mechanism, which is relevant to the cataleptic state 2. The aim of this study was therefore to investigate the effect of the Ros on motor symptoms in an animal model of haloperidol (HAL)-induced catalepsy. Adult male Swiss albino mice (25–30 g) that were obtained from Himachal Institute of Pharmacy, Paonta Sahib (H.P), India, were used. The study was approved by the Institutional Animal Ethics Committee. The mice were maintained at 27°C with 12:12 h light-dark cycle for a period of 7 days prior to the study. They were fed with standard rat chow and water ad libitum. The animals were divided into six groups (n = 6). Group I served as control receiving normal saline, Group II served as negative control receiving HAL 2 mg/kg, Group III served as standard receiving Scopolamine 1.0 mg/kg + HAL 2 mg/kg. Group IV and V received Ros 25 and 50 mg/kg + HAL 2 mg/kg, while Group VI received Ros 50 mg/kg alone. All the drugs were administered orally for 15 days except HAL. Haloperidol was given to the appropriate groups on fifth, tenth, and fifteenth day. The Scopolamine or the Ros was given 30 min prior to the administration of the HAL, according to the individual groups. Catalepsy was assessed by means of a standard bar test on every fifth, tenth, and fifteenth day of the drug treatment, as shown in Table 1. The time duration for which the mouse sustained an imposed position with both the front limbs extended and resting on a 4-cm-high wooden bar (1.0 cm diameter) was measured. The end point of the catalepsy was considered to occur when the mice removed both the front limbs from the bar or if the mice moved its head in an exploratory manner. A cut-off time of 300 seconds was applied. All the observations were made between 14.00 and 16.00 h. The maintenance of the imposed posture for a minimum of 20 seconds was considered to be cataleptic. However, the highest time duration of immobility was noted for all animals. On the fifteenth day, cervical dislocation method was used to sacrifice the animals after recording the immobility score. The assay of super oxide dismutase enzyme (SOD) estimates the ability of the enzyme to inhibit the auto-oxidation of pyrogallol. The units of the SOD enzyme were expressed in milligrams of the total protein 3, 4. The brain isolated from the individual mouse was homogenized (20 w/v) in 10 mM phosphate buffer solution with a pH of 7.8. The homogenate was centrifuged, and 0.1 mL of the homogenate (1:10 dilution) was used for the determination. Table 1 shows that the administration of Scopolamine and both doses of the Ros showed significantly (P < 0.05 and P < 0.01) lower cataleptic scores than in the control group in a dose and time-dependent manner. An elevated SOD activity in the mice brain was observed in the HAL-treated group. The scopolamine and Ros (25 and 50 mg/kg) showed a significant (P < 0.01 and P < 0.001) reduction in SOD activity at both doses with a maximum reduction observed with 50 mg/kg Ros group. Previous studies demonstrated that HAL produced cataleptic effects by mediating the dopamine receptors localized postsynaptically on striatal neurons 5. Super oxide dismutase enzyme is a main factor in oxygen toxicity, constituting as an essential defense against the latter. Reduction in antioxidant enzyme is observed in the presence of free radical quenching agent. Haloperidol administration increases the oxidative stress in the brain tissue 6. The increase in SOD in this study confirms the above hypothesis. This study reveals that the Ros-treated groups significantly in comparison with the scopolamine group reduce (P < 0.05, P < 0.01 and P < 0.001) both oxidative stress and the catalepsy score induced by HAL. This study establishes Ros as a beneficial adjuvant in the treatment of drug-induced extra pyramidal side effects and related disorders. The authors declare no conflict of interest.

Study of the transcytosis of an anti-transferrin receptor antibody with a Fab′ cargo across the blood–brain barrier in mice

One strategy used to transport pharmacologically active substances across the blood–brain barrier (BBB) is to link the substance to a molecule capable of crossing the BBB using a receptor-mediated transcellular transport system in brain capillary endothelial cells. The transferrin receptor (TfR) is related to a transcytosis process in these cells, and the 8D3 antibody, directed against mouse TfR, is able to induce a receptor response. In this work, the potential of 8D3 to carry molecules across the BBB was investigated. This antibody (either unlabeled or FITC-labeled) was intravenously administered to ICR-CD1 mice. Immunocomplexes (ICs) consisting of 8D3 antibody (carrier) and Fab′ fragments (simulated cargo), in some cases directly fluorolabeled with FITC, were also administered to ICR-CD1 mice. At different time-points of recirculation, the IC components were studied using immunohistochemical procedures and fluorescence resonance energy transfer (FRET). The results suggested that 8D3 alone or in an IC with Fab′ fragments entered the endothelial cells. FRET analysis indicated that the colocalization of their fluorescent signals inside the endothelial cells decreased with time, indicating that ICs can be processed and Fab′ fragments probably separated from 8D3. However, neither 8D3 alone nor the IC components crossed the BBB.

Oxidative Damage of Brain Induced by Nano-CdSeS in Mice

In this experiment, the oxidative damage of nano-CdSeS in mice brains was performed. 20 male Kunming mice were divided into 4 groups and 3 experimental groups were exposed to different doses of nano-CdSeS (0.1 mg/mL, 0.2 mg/mL and 0.4 mg/mL) by intravenous administration while the control used saline solution instead. Three days later, the enzymatic activity of superoxide dismutase (SOD), the content of malondialdehyde (MDA) and the damage degree of DNA were determined to assess the oxidative damage in brain tissues. Our results showed that in the experimental groups, SOD activity was inhibited and MDA content was increased as the doses rising, at the same time, tail moment and tail DNA% increased significantly when comparing with the control. And these results exhibited a certain doses-dependency relations. From results above, it demonstrated that oxidative damage of brain induced by nano-CdSeS which enter into blood–brain barrier in mice.

Respiratory toxicity of buprenorphine results from the blockage of P-glycoprotein-mediated efflux of norbuprenorphine at the blood–brain barrier in mice

Deaths due to asphyxia as well as following acute poisoning with severe respiratory depression have been attributed to buprenorphine in opioid abusers. However, in human and animal studies, buprenorphine exhibited ceiling respiratory effects, whereas its metabolite, norbuprenorphine, was assessed as being a potent respiratory depressor in rodents. Recently, norbuprenorphine, in contrast to buprenorphine, was shown in vitro to be a substrate of human P-glycoprotein, a drug-transporter involved in all steps of pharmacokinetics including transport at the blood-brain barrier. Our objectives were to assess P-glycoprotein involvement in norbuprenorphine transport in vivo and study its role in the modulation of buprenorphine-related respiratory effects in mice. University-affiliated research laboratory, INSERM U705, Paris, France. Wild-type and P-glycoprotein knockout female Friend virus B-type mice. Respiratory effects were studied using plethysmography and the P-glycoprotein role at the blood-brain barrier using in situ brain perfusion. Norbuprenorphine(≥ 1 mg/kg) and to a lesser extent buprenorphine (≥ 10 mg/kg) were responsible for dose-dependent respiratory depression combining increased inspiratory (TI) and expiratory times (TE). PSC833, a powerful P-glycoprotein inhibitor, significantly enhanced buprenorphine-related effects on TI (p < .01) and TE (p < .05) and norbuprenorphine-related effects on minute volume (VE, p < .05), TI, and TE (p < .001). In P-glycoprotein-knockout mice, buprenorphine-related effects on VE (p < .01), TE (p < .001), and TI (p < .05) and norbuprenorphine-related effects on VE (p < .05) and TI (p < .001) were significantly enhanced. Plasma norbuprenorphine concentrations were significantly increased in PSC833-treated mice (p < .001), supporting a P-glycoprotein role in norbuprenorphine pharmacokinetics. Brain norbuprenorphine efflux was significantly reduced in PSC833-treated and P-glycoprotein-knockout mice (p < .001), supporting P-glycoprotein-mediated norbuprenorphine transport at the blood-brain barrier. P-glycoprotein plays a key-protective role in buprenorphine-related respiratory effects, by allowing norbuprenorphine efflux at the blood-brain barrier. Our findings suggest a major role for drug-drug interactions that lead to P-glycoprotein inhibition in buprenorphine-associated fatalities and respiratory depression.

Ameliorative Effects of Syzygium jambolanum Extract and its Poly (lactic-co-glycolic) Acid Nano-encapsulated Form on Arsenic-induced Hyperglycemic Stress: A Multi-parametric Evaluation

In South East Asia, groundwater arsenic contamination has become a great menace. Chronic arsenic intoxication leads to a hyperglycemic condition in animals and man. Because of undesirable side-effects and affordability, orthodox medicine, like insulin, is not preferred by many who like natural products instead. Unfortunately, such natural products mostly lack scientific validation. Therefore, we became interested in assessing the efficacy of the ethanolic seed extract of Syzygium jambolanum (SJ), traditionally used against diabetic conditions. We also formulated poly (lactic-co-glycolic) acid (PLGA)-encapsulated nano-SJ (NSJ) and tested whether the ameliorative potentials of SJ could be enhanced by nano-encapsulation. In this study, we conducted both in vitro (in L6 cells) and in vivo (in mice) experiments to assess the relative efficacy of SJ and NSJ. We characterized the physico-chemical features of NSJ by atomic force microscopy and critically analyzed several bio-markers and signal proteins associated with arsenic-induced stress and hyperglycemia. We also determined the relative ameliorative potentials of SJ and NSJ by using standard protocols. NSJ could cross the blood brain barrier in mice. Overall results suggested that NSJ had a greater potential than that of SJ, indicating the possibility of using NSJ in the future drug design and management of arsenic-induced hyperglycemia and stress.