Brain Tissue Concentrations Research Articles

Increased inflammation in BA21 brain tissue from African Americans with Alzheimer's disease.

Chronic neuroinflammation is strongly associated with AD and altered peripheral and central levels of chemokines and cytokines have been frequently described in those with AD. Given the increasing evidence of ethnicity-related differences in AD, it was of interest to determine if those altered chemokine and cytokine levels are ethnicity-related. Because African Americans exhibit a higher incidence of AD and increased symptom severity, we explored chemokine and cytokine concentrations in post-mortem brain tissue from the BA21 region of African Americans and Caucasians with AD using multiplex assays. IL-1β, MIG, TRAIL, and FADD levels were significantly increased in African Americans while levels of IL-3 and IL-8 were significantly decreased. Those effects did not interact with gender; however, overall levels of CCL25, CCL26 and CX3CL1 were significantly decreased in women. The NLRP3 inflammasome is thought to be critically involved in AD. Increased activation of this inflammasome in African Americans is consistent with the current results.

Changes in cytokine and chemokine profiles in mouse serum and brain, and in human neural cells, upon tick-borne encephalitis virus infection

BackgroundTick-borne encephalitis (TBE) is a severe neuropathological disorder caused by tick-borne encephalitis virus (TBEV). Brain TBEV infection is characterized by extensive pathological neuroinflammation. The mechanism by which TBEV causes CNS destruction remains unclear, but growing evidence suggests that it involves both direct neuronal damage by the virus infection and indirect damage caused by the immune response. Here, we aimed to examine the TBEV-infection-induced innate immune response in mice and in human neural cells. We also compared cytokine/chemokine communication between naïve and infected neuronal cells and astrocytes.MethodsWe used a multiplexed Luminex system to measure multiple cytokines/chemokines and growth factors in mouse serum samples and brain tissue, and in human neuroblastoma cells (SK-N-SH) and primary cortical astrocytes (HBCA), which were infected with the highly pathogenic TBEV strain Hypr. We also investigated changes in cytokine/chemokine production in naïve HBCA cells treated with virus-free supernatants from TBEV-infected SK-N-SH cells and in naïve SK-N-SH cells treated with virus-free supernatants from TBEV-infected HBCA cells. Additionally, a plaque assay was performed to assess how cytokine/chemokine treatment influenced viral growth following TBEV infection.ResultsTBEV-infected mice exhibited time-dependent increases in serum and brain tissue concentrations of multiple cytokines/chemokines (mainly CXCL10/IP-10, and also CXCL1, G-CSF, IL-6, and others). TBEV-infected SK-N-SH cells exhibited increased production of IL-8 and RANTES and downregulated MCP-1 and HGF. TBEV infection of HBCA cells activated production of a broad spectrum of pro-inflammatory cytokines, chemokines, and growth factors (mainly IL-6, IL-8, CXCL10, RANTES, and G-CSF) and downregulated the expression of VEGF. Treatment of SK-N-SH with supernatants from infected HBCA induced expression of a variety of chemokines and pro-inflammatory cytokines, reduced SK-N-SH mortality after TBEV infection, and decreased virus growth in these cells. Treatment of HBCA with supernatants from infected SK-N-SH had little effect on cytokine/chemokine/growth factor expression but reduced TBEV growth in these cells after infection.ConclusionsOur results indicated that both neurons and astrocytes are potential sources of pro-inflammatory cytokines in TBEV-infected brain tissue. Infected/activated astrocytes produce cytokines/chemokines that stimulate the innate neuronal immune response, limiting virus replication, and increasing survival of infected neurons.

The effects of abamectin on oxidative stress and gene expression in rat liver and brain tissues: Modulation by sesame oil and ascorbic acid

The present work was designed to assess the modulatory effects of sesame oil (SO) and ascorbic acid (AA) on abamectin (ABM)-induced oxidative stress and altered gene expression of hepatic cytochrome P450 2E1 (CYP-2E1), p38 MAPK, and caspase-3 and cerebral P-glycoprotein (Abcb1a receptor). Male rats were distributed into five groups (6 rats/group), receiving distilled water, ABM 2 mg/kg bwt 1/5 LD50 orally for 5 days, ABM + AA 100 mg/kg bwt orally, ABM + SO 5 ml/kg bwt orally, or ABM + SO + AA at the aforementioned doses. Nineteen compounds were identified in the SO sample by GC–MS analysis, including tetradecane,2,6,10-trimethyl, octadecane, 1-hexadecanol,2-methyl, and octadecane,6-methyl. Abamectin significantly upregulated the hepatic CYP-2E1 expression with excess generation of oxidative radicals, as evident by the significant depletion of reduced glutathione and elevation of malondialdehyde concentration (p ≤ 0.05) in rat liver and brain tissues. Further, ABM significantly increased TNF-α concentration, the expression of caspase-3 and p38 MAPK in the liver, as well as p-glycoprotein and GABA-A receptor in the brain. These results were in line with the observed histopathological changes. Sesame oil and/or AA supplementation alleviated ABM-induced cell damage by modulating all tested parameters. In conclusion, ABM induces oxidative stress and increases the expression of CYP-2E1, caspase-3, and p38 MAPK in the liver, as well as P-gp and GABA-A receptor in the brain. These effects could be ameliorated by SO and AA, alone and in combination, probably due to their anti-oxidant, anti-apoptotic, and gene-regulating activities.

The Molecular Mechanism of Sirt1 Signaling Pathway in Brain Injury of Newborn Rats Exposed to Hyperoxia

The aim of the study was to investigate the changes in the reactive oxygen species (ROS), Sirt1, p53 and acetylated p53 in brain tissue of newborn rats exposed to hyperoxia to clarify the role of Sirt1 signaling pathway in brain injury. Neonate rats were randomly divided into normoxic group and hyperoxic group. Rats in the normoxic group were exposed to room air while the rats in the hyperoxic group were put in a hyperoxic chamber (80 ± 5% oxygen) for 1 to 14 d. Data, including weight growth, the water content of brain tissue, hematoxyline and eosin (H&E) and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (Tunel) stain, ROS expression, the relative expression of Sirt1 mRNA and p53 mRNA, and the protein relative expression of Sirt1, p53 and acetylated p53 were analyzed at 1, 7 and 14 d after exposure. A reduced body weight and increased water content were observed in the brain tissue of hyperoxic group compared to normoxic group. HE staining and Tunel staining of brain tissue suggested that cell damaged after hyperoxic exposure. RT-PCR and Western blot results showed that the expression of Sirt1 in the hyperoxic group was lower than that in the normoxic group while the expression of p53 was higher than that in the normoxic group. In addition, Western blot data indicated acetylated p53 expression was higher in the hyperoxic group. Hyperoxic exposure can lead to brain injury in newborn Sprague-Dawley (SD) rats. These events might be regulated by the Sirt1 pathway, which downregulated the deacetylation of p53.

Effect of Silencing Information Regulator on Rat Cerebral Venous Thrombosis Through Regulating Vascular Endothelial Growth Factor

Cerebral venous thrombosis (CVST) can cause severe dysfunction and even death. Silencing information regulator (SIRT1) involves in neurodegenerative diseases. However, whether SIRT1 participates in CVST is unclear. SD rats were divided into 3 groups, control group; CVST group and SIRT1 group (transfected with AAV-SIRT1 plasmid) followed by analysis of brain tissue SIRT1 and VEGF expression by Real time PCR, neurological deficit scores and brain tissue water content. Brain vascular endothelial cells (bVECs) were cultured and divided into NC group, SIRT1 group and si-SIRT1 group followed by analysis of cell proliferation by MTT assay, Caspase 3 activity, SIRT1 expression by Real time PCR and Western blot and VEGF expression and secretion by Real time PCR and ELISA. SIRT1 expression was decreased and VEGF expression was increased, along with increased score of neurological deficit and water content of brain tissue in CVST rats. Transfection of AAV-SIRT1 plasmid up-regulated SIRT1 expression in CVST rats, inhibited VEGF expression, improved neurological deficit score and brain tissue water content (P < 0.05). Overexpression of SIRT1 in bVECs significantly decreased cell proliferation, elevated Caspase 3 activity, and decreased VEGF expression and secretion, compared to NC group (P < 0.05). Knockdown of SIRT1 expression in bVECs reversed the above changes (P < 0.05). SIRT1 expression is decreased in CVST rats and up-regulation of SIRT1 can inhibit VEGF expression and improve neurological function. SIRT1 can inhibit the proliferation of bVECs and regulate cerebral venous thrombosis by regulating VEGF.

Pharmacokinetics, pharmacodynamics and toxicity of Baicalin liposome on cerebral ischemia reperfusion injury rats via intranasal administration

Baicalin (BA) is a major active component from the traditional Chinese medicine, which has been widely used to treat brain diseases. Previously, the baicalin liposome (BA-LP) was prepared to improve its low bioavailability. However, the existence of the obstacles such as the blood-brian-barrier (BBB) still make it difficult to enter brain effectively. Meanwhile, many reports have shown that drugs can be transported into brain through intranasal administration without the BBB. Therefore, we aim to explore the effect of BA-LP on middle cerebral artery occlusion (MCAO) rats via i.n. administration. The results showed that BA and BA-LP had no obvious impact on mucosa after i.n. administration. And in pharmacokinetics study after i.n. administration, the value of t 1/2 and AUC 0-t in BA-LP group were significantly higher than that of the BA group (p < 0.05), indicating BA-LP could prolong the extension time of BA in vivo and further improve the bioavailability. In the brain biodistribution, the BA-LP group showed a higher BA concentration in brain tissues. Pharmacodynamics studies showed that BA-LP through i.n. administration could significantly improve the neurological deficits, cerebral infarction and brain pathological status in rats with MCAO surgery. Obviously, the BA-LP was more effective after nasal administration than intravenous administration, suggesting the nasal administration is more advantageous route in brain concentration enrichment. In conclusion, BA-LP could be safely used in i.n. administration, which can effectively improve brain targeting effect and thus protect the MCAO rats. Furthermore, successful use of the BA-LP via nasal delivery can provide a model for other drugs with neuroprotective effect and further promote the cure rate of brain diseases.

Lymphatic clearance is the main drainage route of lamotrigine-loaded micelles following delivery to the brain.

This study aimed to investigate the clearance pathways of lamotrigine (LTG)-loaded micelles by intranasal administration and intracerebral injection in the brain and whether nanoparticles can induce the inflammation promoted by interleukin-6 (IL-6), accelerating the phagocytosis of drug particles in the brain and drainage through lymphatics. The drug concentrations in the deep cervical lymph node, superficial cervical lymph node, brain tissues and jugular vein, the pharmacokinetic parameters, and the concentrations of IL-6 in deep cervical lymph node and brain tissues were investigated following UPLC/MS, DAS3.0, ELISA statistically analysed. The AUC0- t of deep cervical lymph node after intranasal and intracerebral injection was 1.93, 2.77, 1.34 times and 3.06, 16.4, 3.34 times higher compared with the superficial cervical lymph node, jugular vein and brain tissue, respectively. After intranasal administration of lamotrigine-loaded micelles for 30min, the IL-6 concentrations in deep cervical lymph node and brain tissue were significantly increased (P<0.05). These results suggested that lamotrigine micelles were primarily cleared from the brain by lymphatics rather than blood clearance. Also, the nanoparticle induced the increase in IL-6 level after entering the brain suggested that nanoparticles might induce the inflammation promoted by IL-6 in the brain, accelerating the clearance of drug particles in the brain and drainage through lymphatics.

Methylsulfonylmethane (MSM): A chemical shift reference for 1 H MRS of human brain.

We investigate the potential of a common dietary supplement, methylsulfonylmethane (MSM), to act as a chemical shift reference for in vivo 1 H MR spectroscopy (MRS). The scope of the investigation is 2-fold: (1) We use high-resolution nuclear MR (NMR) measurements of the chemical shift values of MSM to establish the stability of MSM resonance across the ranges of pH and temperature, and (2) we demonstrate MR properties of MSM in the healthy human brain. The relationship of chemical shift with temperature and pH is examined using high-resolution 1 H NMR (14.1T) spectra of MSM in aqueous solution. MSM concentration in human brain tissue was measured as a function of time, together with the relaxation properties in the brain using 1 H MRS at 3T. The chemical shift of MSM remains stable in the range of the biologically relevant temperatures and pH values. The chemical shift at pH = 7.2 and 37°C was measured to be 3.142 ppm (relative to DSS, a common water-soluble NMR reference compound). Time course in the brain tissue in vivo confirmed an observable MSM signal 10 minutes after oral intake and a stable signal intensity within a ~3-hour window. The chemical and biological properties of MSM-rapid crossing of the blood-brain barrier, water solubility, a singlet resonance resolved from metabolite resonances, chemical shift stability with respect to pH/temperature, and stable temporal presence in the brain-lead us to propose its use as a frequency reference for MRS.

Delamanid Central Nervous System Pharmacokinetics in Tuberculous Meningitis in Rabbits and Humans.

Central nervous system tuberculosis (TB) is devastating and affects vulnerable populations. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculous meningitis (TBM) specifically are nearly uniformly fatal, with little information being available to guide the treatment of these patients. Delamanid (DLM), a nitro-dihydro-imidazooxazole, is a new, well-tolerated anti-TB drug with a low MIC (1 to 12 ng/ml) against Mycobacterium tuberculosis It is used for the treatment of pulmonary MDR-TB, but pharmacokinetic (PK) data for DLM in the central nervous system (CNS) of patients with TBM are not available. In the present study, we measured DLM concentrations in the brain and cerebrospinal fluid (CSF) of six rabbits with and without experimentally induced TBM receiving single-dose DLM. We report the steady-state CSF concentrations from three patients receiving DLM as part of multidrug treatment who underwent therapeutic drug monitoring. Drug was quantified using liquid chromatography-tandem mass spectrometry. In rabbits and humans, mean concentrations in CSF (in rabbits, 1.26 ng/ml at 9 h and 0.47 ng/ml at 24 h; in humans, 48 ng/ml at 4 h) were significantly lower than those in plasma (in rabbits, 124 ng/ml at 9 h and 14.5 ng/ml at 24 h; in humans, 726 ng/ml at 4 h), but the estimated free CSF/plasma ratios were generally >1. In rabbits, DLM concentrations in the brain were 5-fold higher than those in plasma (means, 518 ng/ml at 9 h and 74.0 ng/ml at 24 h). All patients with XDR-TBM receiving DLM experienced clinical improvement and survival. Collectively, these results suggest that DLM achieves adequate concentrations in brain tissue. Despite relatively low total CSF drug levels, free drug may be sufficient and DLM may have a role in treating TBM. More studies are needed to develop a fuller understanding of its distribution over time with treatment and clinical effectiveness.

Elimination of glutamate using CRRT for 72 h in patients with post-cardiac arrest syndrome: A randomized clinical pilot trial

AimGlutamine and glutamate are major mediators of secondary brain cell death during post-cardiac arrest syndrome. As there is an equilibrium between brain tissue and plasma concentrations of glutamine and glutamate, their elimination from systemic circulation by extracorporeal blood purification may ultimately lead to reduced secondary cell death in the brain. We hypothesized that systemic glutamine and glutamate can be significantly reduced by continuous venovenous hemodiafiltration (CVVHDF). MethodsThis was a prospective, randomized clinical trial in post cardiac-arrest survivors evaluating standard of care or additional CVVHDF over 72 h immediately after admission. Glutamine and glutamate plasma concentrations were analyzed at eight time points in both groups. Primary endpoint was reduction of glutamine and glutamate plasma concentrations. The trial has been registered at clinical trial.gov (NCT02963298). ResultsIn total, 41 patients were randomized over a period of 12 months (control n = 21, CVVHDF n = 20). The primary aim reduction of glutamine and glutamate plasma concentrations by CVVHDF, was not achieved; both groups-maintained concentrations within a normal range over the study period (glutamate: 4.7–11.1 mg/dL; glutamine: 0.2–3.7 mg/dL). However, post-filter concentrations of glutamine and glutamate in CRRT patients were significantly decreased as compared to pre-filter concentrations (glutamate: pre-filter median 8.85 mg/dL IQR 7.1–9.6; post-filter 0.95 mg/dL IQR 0.5–2; p < 0.001; glutamine: pre-filter 0.7 mg/dL IQR 0.6–1; post-filter 0.2 mg/dL IQR 0–0.2; p < 0.001). ConclusionIn this trial, CVVHDF was not able to statistically significantly lower systemic plasma glutamine and glutamate levels. Post-cardiac arrest patients had plasma glutamine and glutamate levels within the normal range.

Micafungin concentrations in human brain tissue and cerebrospinal fluid

Micafungin concentrations in human brain tissue and cerebrospinal fluid

Preparation, preliminary pharmacokinetics and brain tissue distribution of Tanshinone IIA and Tetramethylpyrazine composite nanoemulsions

Objective: Tanshinone IIA (TSN) and Tetramethylpyrazine (TMP) were combined in a composite, oil-in-water nanoemulsions (TSN/TMP O/W NEs) was prepared to prolong in vitro and vivo circulation time, and enhance the bioavailability of TSN.Material and methods: Physicochemical characterization of TSN/TMP O/W NEs was characterized systematically. The in vitro dissolution and in vivo pharmacokinetic experiments of TSN/TMP O/W NEs were also evaluated.Result: A formulation was optimized, yielding a 32.5 nm average particle size, an encapsulation efficiency of over 95 %, and were spherical in shape as shown by TEM. TSN/TMP O/W NEs were shown to extend the release and availability in vitro compared to raw compounds. In pharmacokinetic study, the AUC0→∞ and t1/2 of the TSN/TMP O/W NEs were 481.50 mg/L*min and 346.39 min higher than TSN solution, respectively. Brain tissue concentration of TSN was enhanced with TSN/TMP O/W NEs over raw TSN and even TSN O/W NEs.Conclusions: Therefore, nanoemulsions are an effective carrier to increase encapsulation efficiency of drugs, improve bioavailability and brain penetration for TSN – which is further enhanced by pairing with the co-delivery of TMP, providing a promising drug delivery.

Upregulation of reduced folate carrier by vitamin D enhances brain folate uptake in mice lacking folate receptor alpha

Folates are critical for central nervous system function. Folate transport is mediated by 3 major pathways, reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptor alpha (FRα/Folr1), known to be regulated by ligand-activated nuclear receptors. Cerebral folate delivery primarily occurs at the choroid plexus through FRα and PCFT; inactivation of these transport systems can result in very low folate levels in the cerebrospinal fluid causing childhood neurodegenerative disorders. These disorders have devastating effects in young children, and current therapeutic approaches are not sufficiently effective. Our group has previously reported in vitro that functional expression of RFC at the blood-brain barrier (BBB) and its upregulation by the vitamin D nuclear receptor (VDR) could provide an alternative route for brain folate uptake. In this study, we further demonstrated in vivo, using Folr1 knockout (KO) mice, that loss of FRα led to a substantial decrease of folate delivery to the brain and that pretreatment of Folr1 KO mice with the VDR activating ligand, calcitriol (1,25-dihydroxyvitamin D3), resulted in over a 6-fold increase in [13C5]-5-formyltetrahydrofolate ([13C5]-5-formylTHF) concentration in brain tissues, with levels comparable to wild-type animals. Brain-to-plasma concentration ratio of [13C5]-5-formylTHF was also significantly higher in calcitriol-treated Folr1 KO mice (15-fold), indicating a remarkable enhancement in brain folate delivery. These findings demonstrate that augmenting RFC functional expression at the BBB could effectively compensate for the loss of Folr1-mediated folate uptake at the choroid plexus, providing a therapeutic approach for neurometabolic disorders caused by defective brain folate transport.

Effects of astaxanthin onaxonal regeneration via cAMP/PKA signaling pathway in mice with focal cerebral infarction.

To investigate the effect of astaxanthin on the neurological function of the middle cerebral artery occlusion (MCAO) mice and its possible mechanism. The male C57BL/6 mice were selected to establish the model of MCAO via electrocoagulation, and they were randomly divided into 4 groups: the sham operation group (Sham group), the cerebral ischemia model group (MCAO group), the astaxanthin intervention group (gavage with 30 mg/kg astaxanthin for 28 days, twice a day; Ast group), and astaxanthin + H89 group (Ast + H89 group). At 3, 7, 14, and 28 d after the operation, the Rotarod test and the balance beam footstep error test were performed. The brain tissues were taken for immunofluorescence to observe the expression of the growth-associated protein 43 (GAP43) in the cortex around the infarction. The GAP43 protein and mRNA levels in the cortex around the infarction were detected via Western blotting, and the Reverse Transcription-Polymerase Chain Reaction (RT-PCR), the levels of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) in the bilateral cerebral cortex were detected via enzyme-linked immunosorbent assay (ELISA), and the PKAc and phosphorylated-cAMP-response element-binding protein (p-CREB) levels in the bilateral cerebral cortex were detected via Western blotting. Biotin dextran amine (BDA) was injected at 14 d after the operation, and the brain was taken at 28 d. The BDA-labeled neurons or axons were observed in the bilateral cortex via immunohistochemistry and immunofluorescence, and the colocalization of BDA and GAP43 in the cortex around the infarction was observed using double immunofluorescence staining. Compared with those in the MCAO group, the mean residence time in the Rotarod test was significantly increased, and the times of the footstep error on the balance beam were significantly reduced in the Ast group. In the Ast group, the expression of GAP43 in the cortex around the infarction, the GAP43 protein, and the mRNA levels were all significantly elevated. Immunofluorescence showed that in the Ast group, the number of the labeled neurons and axons in the bilateral cortex was slightly larger than that in the other groups, and the number of labeled axonal fibers in the ischemic cortex was significantly increased. The colocalization area of BDA and GAP43 was observed, and it was found that the positive area in the Ast group was significantly larger than that in the MCAO group. The cAMP level was higher in the Ast group and Ast + H89 group at 7, 14, and 28 d after operation, while the PKA level was lower in the Ast + H89 group at 7 and 14 d after operation and higher in the Ast group at 7, 14, and 28 d after operation. The results of the Western blotting manifested that the PKAc and p-CREB levels were upregulated in the Ast group at 7, 14, and 28 d after the operation, and downregulated in the Ast + H89 group at 7, 14, and 28 d after the operation. Astaxanthin activates the cAMP/PKA/CREB signaling pathway by increasing the cAMP concentration in brain tissues, ultimately promoting the axonal regeneration in the cerebral cortex and improving the motor function.

Dexmedetomidine Inhibits Endoplasmic Reticulum Stress Response and Improves Neurological Function After Traumatic Brain Injury in Rats

Dexmedetomidine (DEX) can inhibit neuronal apoptosis. There are multiple secondary lesions following traumatic brain injury (TBI). Our study evaluated the application of DEX in TBI by observing neurological impairment score, brain edema, nerve cells apoptosis, and endoplasmic reticulum stress response (ERS). SD rats were selected to establish TBI model using modified Feeney method and then randomly divided into sham operation group (A), TBI group (B), TBI + DEX group (C), and TBI + DEX + endoplasmic reticulum stress inducer 2-deoxyglucose (2-DG) group (D). The neurological injury severity score (mNSS) was measured on day 1, 3, and 7 after injury. The water content of brain tissue was measured. The pathology of brain tissue was observed on the 7th day after craniocerebral injury. Caspase-12 and IRE-1 were determined by Western blot. Apoptosis was assessed by TUNEL assay. CHOP and Glucose Regulatory Protein 78 (GRP78) expressions were detected by immunohistochemistry (IHC). Compared with group A, mNSS scores, brain water content, and neuronal apoptosis were increased, and caspase-12, IRE-1, CHOP, and GRP78 proteins were upregulated in groups B, C, and D (P &lt; 0.05). Compared to group B, the neurological function was improved, brain water content and neuronal apoptosis were decreased, and caspase-12, IRE-1, CHOP, and GRP78 protein expressions were reduced in group C (P &lt; 0.05). Neurological impairment was aggravated, brain water content and nerve cell apoptosis were increased, and caspase-12, IRE-1, CHOP, and GRP78 protein expressions were upregulated in group D compared to group C (P &lt; 0.05). DEX treatment can alleviate brain edema after TBI and inhibit neuronal apoptosis, which has neuroprotective effects. Its mechanism may be related to ERS after TBI inhibition.

Oxycodone concentrations in the central nervous system and cerebrospinal fluid after epidural administration to the pregnant ewe.

The main sites of the analgesic action of oxycodone are the brain and spinal cord. The present study describes the concentrations of oxycodone and its metabolites in the brain and spinal cord after epidural administration to the ewe. Twenty pregnant ewes undergoing laparotomy were randomized into two groups to receive epidural oxycodone: infusion group (n=10, 0.1mg·kg-1 bolus followed by continuous infusion of 0.05mg·kg-1 ·h-1 for five days) or repeated boluses group (n=10, 0.2+2x0.1mg·kg-1 bolus followed by a 0.2mg·kg-1 bolus every 12hours for five days). After five days of oxycodone administration, arterial blood samples were collected, the sheep were killed, and a CSF sample and tissue samples from the cortex, thalamus, cerebellum and spinal cord were obtained for the quantification of oxycodone and its main metabolites. The median plasma and CSF concentrations of oxycodone were 9.0 and 14.2ng·mL-1 after infusion and 0.4 and 1.1ng·mL-1 after repeated boluses. In the infusion group, the cortex, thalamus and cerebellum oxycodone concentrations were 4-8 times higher and in the spinal cord 1310 times higher than in plasma. In the repeated boluses group, brain tissue concentrations were similar in the three areas, and in the spinal cord were 720 times higher than in plasma. Oxymorphone was the main metabolite detected, which accumulated in the brain and spinal cord tissue. In conclusion, first, accumulation of oxycodone and oxymorphone in the CNS was observed, and second, high spinal cord concentrations suggest that epidural oxycodone may provide segmental analgesia.

Cerebrospinal Fluid and Brain Tissue Penetration of Tenofovir, Lamivudine, and Efavirenz in Postmortem Tissues with Cryptococcal Meningitis.

The central nervous system (CNS) is a known HIV reservoir, yet little is known about drug exposure in the brain. Our primary objective was to quantify exposure of three common antiretrovirals in brain tissue and compare exposures to plasma and cerebrospinal fluid (CSF). We also sought to identify pockets of brain most vulnerable to inadequate drug exposures and examine the role of meningitis in drug penetration into the CNS. Tenofovir, lamivudine, and efavirenz concentrations were measured using liquid chromatography and tandem mass spectrometry in plasma and CSF from 14 individuals with HIV, 7 with cryptococcal meningitis. In four individuals (three with meningitis) drug concentrations were also measured in 13 distinct brain tissue regions. In subjects with meningitis, geometric mean ratio (95% confidence interval) of tenofovir CSF to plasma was 66% (7–598%) and 14% (6–31%) in subjects without meningitis. Lamivudine CSF penetration was 100% (25–409%) in subjects with meningitis and 30% (24–37%) in subjects without meningitis. Tenofovir brain tissue concentrations were 36% (14–124%) of plasma and 49% (1–572%) of CSF. Lamivudine brain concentrations were 37% (23–64%) of plasma and 27% (1–104%) of CSF. Efavirenz brain tissue concentrations were 128% (108–179%) of plasma. Tissues collected postmortem provide a unique opportunity to assess drug distribution in tissues difficult to sample in living subjects. CSF is a poor surrogate for drug exposure throughout the CNS. Antiretrovirals differentially penetrate into the CNS and penetration may be enhanced by meningitis.

Effects of the N-methyl-d-aspartate receptor antagonist, MK-801, on spatial memory and influence of the route of administration

The N-methyl-d-aspartate receptor antagonist, MK-801, is widely used to induce memory and learning impairments in preclinical studies. MK-801 is mainly injected intraperitoneally (i.p.) at doses that result in cognitive impairment and induction of motor or sensory disturbances. The aim of this study was to compare the behavioral outcomes when different administration routes (subcutaneous (s.c.) and i.p.) and MK-801 doses (0.01, 0.05, and 0.1 mg/kg) are employed in the Morris water maze (MWM) task. We also assessed the pharmacokinetics of MK-801 in rat blood plasma and its bioavailability in brain tissue.The concentrations of MK-801 in brain tissue and blood plasma were significantly higher after s.c. than i.p. administration. MK-801 administered via the s.c. route at doses of 0.1 and 0.05 mg/kg significantly impaired learning on all training days in the MWM task compared to i.p. administration at the same doses. Memory in the probe trial was significantly impaired after MK-801 administration via both routes at all doses. MK-801 also induced locomotor disturbances after i.p. and s.c. administration at the highest dose (0.1 mg/kg).Our data suggest that s.c. administration leads to higher MK-801 concentrations in brain tissue and blood plasma and evidently impairs spatial learning and memory compared to i.p. administration at the same dose. Knowledge of MK-801 concentrations in the brain and blood and the effects of the compound on memory processes and locomotor activity enable the choice of more targeted routes and doses of administration in preclinical studies.

Tacrine and its 7-methoxy derivate; time-change concentration in plasma and brain tissue and basic toxicological profile in rats

The search for tacrine derivatives, as potential Alzheimer´s disease treatment, is still being at the forefront of scientific efforts. 7-MEOTA was found to be a potent, centrally active acetylcholinesterase inhibitor free of the serious side effects observed for tacrine. Unfortunately, a relevant argumentation about pharmacokinetics and potential toxicity is incomplete; information about tacrine derivatives absorption and especially CNS penetration are still rare as well as detailed toxicological profile in vivo. Although the structural changes between these compounds are not so distinctive, differences in plasma profile and CNS targeting were found. The maximum plasma concentration were attained at 18th min (tacrine; 38.20 ± 3.91 ng/ml and 7-MEOTA; 88.22 ± 15.19 ng/ml) after i.m. application in rats. Although the brain profiles seem to be similar; tacrine achieved 19.34 ± 0.71 ng/ml in 27 min and 7-MEOTA 15.80 ± 1.13 ng/ml in 22 min; the tacrine Kp (AUCbrain/AUCplasma) fit 1.20 and was significantly higher than 7-MEOTA Kp 0.10. Administration of tacrine and 7-MEOTA showed only mild elevation of some biochemical markers following single p.o. application in 24 hours and 7 days. Also histopathology revealed only mild-to-moderate changes following repeated p.o. administration for 14 days. It seems that small change in tacrine molecule leads to lower ability to penetrate through the biological barriers. The explanation that lower p.o. acute toxicity of 7-MEOTA depends only on differences in metabolic pathways may be now revised to newly described differences in pharmacokinetic and toxicological profiles.

DL-3-n-butylphthalide protects the blood-brain barrier against ischemia/hypoxia injury via upregulation of tight junction proteins.

Background:The increased permeability of the blood-brain barrier (BBB) induced by ischemia/hypoxia is generally correlated with alteration of tight junctions (TJs). DL-3-n-butylphthalide (NBP) has been shown to exert neuroprotective effects after ischemic injury. However, few studies have assessed the correlation between NBP and TJs. This study aimed to investigate the potential effect of NBP on the TJ proteins claudin-5, zonula occludens-1 (ZO-1), and occludin during brain ischemia.Methods:A chronic cerebral hypoperfusion (CCH) Sprague-Dawley rat model was established, and NBP (20, 40, or 80 mg/kg, gavage, once a day) treatment was performed for 14 days. NBP (0.1 or 1.0 μmol/L) pre-treatment was applied to an in vitro hypoxia microvascular endothelial cell model (1% O2, 24 h). BBB permeability was assessed by performing the Evans blue assay. The expressions and localization of claudin-5, ZO-1, occludin, phosphorylated/total protein kinase B (p-Akt/Akt), phosphorylated/total glycogen synthase kinase 3β (GSK-3β)/GSK-3β, and β-catenin/β-actin were evaluated by Western blotting or immunofluorescence. Reactive oxygen species (ROS) generation was measured by flow cytometry analysis. TJ ultrastructure was observed by transmission electron microscopy.Results:In CCH rats, treatment with 40 and 80 mg/kg NBP decreased the Evans blue content in brain tissue (9.0 ± 0.9 μg/g vs. 12.3 ± 1.9 μg/g, P = 0.005; 6.7 ± 0.6 μg/g vs. 12.3 ± 1.9 μg/g, P < 0.01), increased the expression of claudin-5 (0.79 ± 0.08 vs. 0.41 ± 0.06, P < 0.01; 0.97 ± 0.07 vs. 0.41 ± 0.06, P < 0.01), and elevated the ZO-1 protein level (P < 0.05) in brain microvascular segments in a dose-dependent manner in comparison with the corresponding values in the model group. There was no significant difference in occludin expression (P > 0.05). In the hypoxia cell model, NBP pre-treatment improved TJ ultrastructure, decreased intracellular ROS level, and increased the expression of claudin-5 (P < 0.01) and ZO-1 (P < 0.01) in comparison with the corresponding values in the hypoxia group. NBP treatment also elevated the relative expression levels of p-Akt/Akt, p-GSK-3β/GSK-3β, and β-catenin/β-actin in comparison with the corresponding values in the hypoxia group (all P < 0.05).Conclusion:NBP improves the barrier function of BBB against ischemic injury by upregulating the expression of TJ proteins, possibly by reducing oxidative stress and activating the Akt/GSK-3β/β-catenin signaling pathway.