Biomedical subjects

David W Busija

Publications and source records attributed to David W Busija.

At least 19 recordsLinked to original sources

PubMed2007

Contribution of poly(ADP-ribose) polymerase to postischemic blood-brain barrier damage in rats.

The nuclear enzyme poly(ADP-ribose) polymerase (PARP) is activated by oxidative stress and plays a significant role in postischemic brain injury. We assessed the contribution of PARP activation to the blood-brain barrier (BBB) disruption and edema formation after ischemia-reperfusion. In male Wistar rats, global cerebral ischemia was achieved by occluding the carotid arteries and lowering arterial blood pressure for 20 mins. The animals were treated with saline or with the PARP inhibitor N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-N, N-dimethylacetamide.HCl (PJ34); (10 mg/kg, i.v.) before ischemia. After 40 mins, 24, and 48 h of reperfusion, the permeability of the cortical BBB was determined after Evans Blue (EB) and Na-fluorescein (NaF) administration. The water content of the brain was also measured. The permeability of the BBB for EB increased after ischemia-reperfusion compared with the nonischemic animals after 24 and 48 h reperfusion but PARP inhibition attenuated this increase at 48 h (nonischemic: 170+/-9, saline: 760+/-95, PJ34: 472+/-61 ng/mg tissue). The extravasation of NaF showed similar changes and PJ34 post-treatment attenuated the permeability increase even at 24 h. PARP inhibition decreased the brain edema seen at 48 h. Because PARP has proinflammatory properties, the neutrophil infiltration of the cortex was determined, which showed lower values after PJ34 treatment. Furthermore, PJ34 treatment decreased the loss of the tight junction protein occludin at 24 and 48 h. The inhibition of PARP activity accompanied by reduced post-ischemic BBB disturbance and decreased edema formation suggests a significant role of this enzyme in the development of cerebral vascular malfunction

Animals↗

PubMed2006

Adaptation of the hypothalamic blood flow to chronic nitric oxide deficiency is independent of vasodilator prostanoids.

The aim of our study was to investigate the adaptation of the hypothalamic circulation to chronic nitric oxide (NO) deficiency in rats. Hypothalamic blood flow (HBF) remained unaltered during chronic oral administration of the NO synthase (NOS) inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME, 1 mg/ml drinking water) although acute NOS blockade by intravenous l-NAME injection (50 mg/kg) induced a dramatic HBF decrease. In chronically NOS blocked animals, however, acute l-NAME administration failed to influence the HBF. Reversal of chronic NOS blockade by intravenous l-arginine infusion evoked significant hypothalamic hyperemia suggesting the appearance of a compensatory vasodilator mechanism in the absence of NO. In order to clarify the potential involvement of vasodilator prostanoids in this adaptation, cyclooxygenase (COX) mRNA and protein levels were determined in the hypothalamus, but none of the known isoenzymes (COX-1, COX-2, COX-3) showed upregulation after chronic NOS blockade. Furthermore, levels of vasodilator prostanoid (PGI(2), PGE(2) and PGD(2)) metabolites were also not elevated. Interestingly, however, hypothalamic levels of vasoconstrictor prostanoids (TXA(2) and PGF(2alpha)) decreased after chronic NOS blockade. COX inhibition by indomethacin but not by diclofenac decreased the HBF in control animals. However, neither indomethacin nor diclofenac induced an altered HBF-response after chronic l-NAME treatment. Although urinary excretion of PGI(2) and PGE(2) metabolites markedly increased during chronic NOS blockade, indicating COX activation in the systemic circulation, we conclude that the adaptation of the hypothalamic circulation to the reduction of NO synthesis is independent of vasodilator prostanoids. Reduced release of vasoconstrictor prostanoids, however, may contribute to the normalization of HBF after chronic loss of NO.

Adaptation, Physiological↗

PubMed2006

Human heart mitochondria do not produce physiologically relevant quantities of nitric oxide.

Previous studies raised the possibility that nitric oxide synthase is present in heart mitochondria (mtNOS) and the existence of such an enzyme became generally accepted. However, original experimental evidence is rather scarce and positive identification of the enzyme is lacking. We aimed to detect an NOS protein in human and mouse heart mitochondria and to measure the level of NO released from the organelles. Western blotting with 7 different anti-NOS antibodies failed to detect a NOS-like protein in mitochondria. Immunoprecipitation or substrate-affinity purification of the samples concentrated NOS in control preparations but not in mitochondria. Release of NO from live respiring human mitochondria was below 2 ppb after 45 min of incubation. In a bioassay system, mitochondrial suspension failed to cause vasodilation of human mammary artery segments. These results indicate that mitochondria do not produce physiologically relevant quantities of NO in the heart and are unlikely to have any physiological importance as NO donors, nor do they contain a recognizable mtNOS enzyme.

Animals↗

PubMed2006

Myocardial preconditioning against ischemia-reperfusion injury is abolished in Zucker obese rats with insulin resistance.

Insulin resistance (IR) precedes the onset of Type 2 diabetes, but its impact on preconditioning against myocardial ischemia-reperfusion injury is unexplored. We examined the effects of diazoxide and ischemic preconditioning (IPC; 5-min ischemia and 5-min reperfusion) on ischemia (30 min)-reperfusion (240 min) injury in young IR Zucker obese (ZO) and lean (ZL) rats. ZO hearts developed larger infarcts than ZL hearts (infarct size: 57.3 +/- 3% in ZO vs. 39.2 +/- 3.2% in ZL; P < 0.05) and also failed to respond to cardioprotection by IPC or diazoxide (47.2 +/- 4.3% and 52.5 +/- 5.8%, respectively; P = not significant). In contrast, IPC and diazoxide treatment reduced the infarct size in ZL hearts (12.7 +/- 2% and 16.3 +/- 6.7%, respectively; P < 0.05). The mitochondrial ATP-activated potassium channel (K(ATP)) antagonist 5-hydroxydecanoic acid inhibited IPC and diazoxide-induced preconditioning in ZL hearts, whereas it had no effect on ZO hearts. Diazoxide elicited reduced depolarization of isolated mitochondria from ZO hearts compared with ZL (73 +/- 9% in ZL vs. 39 +/- 9% in ZO; P < 0.05). Diazoxide also failed to enhance superoxide generation in isolated mitochondria from ZO compared with ZL hearts. Electron micrographs of ZO hearts revealed a decreased number of mitochondria accompanied by swelling, disorganized cristae, and vacuolation. Immunoblots of mitochondrial protein showed a modest increase in manganese superoxide dismutase in ZO hearts. Thus obesity accompanied by IR is associated with the inability to precondition against ischemic cardiac injury, which is mediated by enhanced mitochondrial oxidative stress and impaired activation of mitochondrial K(ATP).

Animals↗

PubMed2006

The mitochondrial K(ATP) channel opener BMS-191095 reduces neuronal damage after transient focal cerebral ischemia in rats.

Activation of mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels protects the brain against ischemic or chemical challenge. Unfortunately, the prototype mitoK(ATP) channel opener, diazoxide, has mitoK(ATP) channel-independent actions. We examined the effects of BMS-191095, a novel selective mitoK(ATP) channel opener, on transient ischemia induced by middle cerebral artery occlusion (MCAO) in rats. Male Wister rats were subjected to 90 mins of MCAO. BMS-191095 (25 microg; estimated brain concentration of 40 micromol/L) or vehicle was infused intraventricularly before the onset of ischemia. In addition, the effects of BMS-191095 on plasma and mitochondrial membrane potentials and reactive oxygen species (ROS) production in cultured neurons were examined. Finally, we determined the effects of BMS-191095 on cerebral blood flow (CBF) and potassium currents in cerebrovascular myocytes. Treatment with BMS-191095 24 h before the onset of ischemia reduced total infarct volume by 32% and cortical infarct volume by 38%. However, BMS-191095 administered 30 or 60 mins before MCAO had no effect. The protective effects of BMS-191095 were prevented by co-treatment with 5-hydroxydecanoate (5-HD), a mitoK(ATP) channel antagonist. In cultured neurons, BMS-191095 (40 micromol/L) depolarized the mitochondria without affecting ROS levels, and this effect was inhibited by 5-HD. BMS-191095, similar to the vehicle, caused an unexplained but modest reduction in the CBF. Importantly, BMS-191095 did not affect either the potassium currents in cerebrovascular myocytes or the plasma membrane potential of neurons. Thus, BMS-191095 afforded protection against cerebral ischemia by delayed preconditioning via selective opening of mitoK(ATP) channels and without ROS generation.

Animals↗

PubMed2006

Adrenomedullin 2 protects rat cerebral endothelial cells from oxidative damage in vitro.

Adrenomedullin 2 (AM2, intermedin) is a recently identified new member of the calcitonin gene-related peptide family. We examined whether AM2 can attenuate the increased blood-brain barrier permeability and cerebral endothelial cell (CEC) death induced by oxidative stress in vitro. Hydrogen peroxide (H(2)O(2), 0.5 mM) induced a continuous decrease of the transendothelial electrical resistance (TEER) and resulted in intercellular gap formations in rat CECs co-cultured with astrocytes. AM2 induced cAMP and nitric oxide production, increased TEER, enhanced peripheral localization of F-actin bands, and attenuated the increased permeability induced by H(2)O(2). AM2 treatment preserved mitochondrial membrane potential and improved CEC viability in H(2)O(2) treated cultures. These effects of AM2 were similar to those what were reported for adrenomedullin. These results suggest that AM2 protects CECs against oxidative injury in vitro.

Adrenomedullin↗

PubMed2006

Kynurenic acid attenuates NMDA-induced pial arteriolar dilation in newborn pigs.

The excitatory amino acid glutamate is a potent vasodilator in the central nervous system. Glutamate-induced vasodilation is mediated primarily by N-methyl-D-aspartate (NMDA) and AMPA/kainate (KAIN) receptors. We have now tested whether two metabolites of the kynurenine pathway of tryptophan degradation acting at the NMDA receptor, the antagonist kynurenic acid (KYNA) and the agonist quinolinic acid (QUIN), are capable of modulating the dilation of pial arterioles. The closed cranial window technique was used, and changes in vessel diameter ( approximately 100 microm) were analyzed in anesthetized newborn piglets. Topical application of NMDA (10(-4) M) or KAIN (5 x 10(-5) M) resulted in marked vasodilation (44 +/- 5% and 39 +/- 4%, respectively). Neither KYNA nor QUIN (both at 10(-5) to 10(-3) M) affected the vessel diameter when applied alone. Co-application of KYNA dose-dependently reduced the vasodilation caused by 10(-4) M NMDA and also attenuated the KAIN-induced response. Ten minutes of global cerebral ischemia did not modify the interaction between KAIN and KYNA. In contrast, KYNA did not affect vasodilation to hypercapnia, elicited by the inhalation of 10% CO2. Moreover, endogenous levels of KYNA and QUIN in the cerebral cortex, hippocampus and thalamus were found to be essentially unchanged during the early reperfusion period (0.5-2 h) following an episode of cerebral ischemia. Our data are relevant for the use of drugs that target the kynurenine pathway for therapeutic interventions in cerebrovascular diseases.

Analysis of Variance↗

PubMed2006

Mitochondria produce reactive nitrogen species via an arginine-independent pathway.

We measured the contribution of mitochondrial nitric oxide synthase (mtNOS) and respiratory chain enzymes to reactive nitrogen species (RNS) production. Diaminofluorescein (DAF) was applied for the assessment of RNS production in isolated mouse brain, heart and liver mitochondria and also in a cultured neuroblastoma cell line by confocal microscopy and flow cytometry. Mitochondria produced RNS, which was inhibited by catalysts of peroxynitrite decomposition but not by nitric oxide (NO) synthase inhibitors. Disrupting the organelles or withdrawing respiratory substrates markedly reduced RNS production. Inhibition of complex I abolished the DAF signal, which was restored by complex II substrates. Inhibition of the respiratory complexes downstream from the ubiquinone/ubiquinol cycle or dissipating the proton gradient had no effect on DAF fluorescence. We conclude that mitochondria from brain, heart and liver are capable of significant RNS production via the respiratory chain rather than through an arginine-dependent mtNOS.

Animals↗

PubMed2006

Transient glucose and amino acid deprivation induces delayed preconditioning in cultured rat cortical neurons.

Several studies have demonstrated that glucose deprivation, combined either with anoxia or with the inhibition of oxidative phosphorylation, leads to the development of ischemic tolerance in neurons. The aim of our experiments was to investigate whether similar effects could be achieved by transient energy deprivation without either anoxia or the inhibition of the electron transfer chain. Preconditioning was carried out by incubating primary rat cortical neuronal cultures for 3, 6 or 9 h in a glucose- and amino acid-free balanced salt solution supplemented with B27 in normoxic conditions. After 24 h, neuronal cultures were exposed to oxygen-glucose deprivation, glutamate or hydrogen peroxide. Cell viability was measured 24 h after the lethal insults. Potential mechanisms that can influence free radical production were also examined. Energy deprivation protected neuronal cells against lethal stimuli (e.g. cell survival after oxygen-glucose deprivation was 33.1 +/- 0.52% in the untreated group and 80.1 +/- 1.27% in the 9-h energy deprivation group), reduced mitochondrial membrane potential, decreased free radical formation, attenuated the intracellular free calcium surge upon glutamate receptor stimulation, and resulted in an elevated level of GSH. Our findings show that transient energy deprivation induces delayed preconditioning and prevents oxidative injuries and neuronal cell death.

Adenosine Triphosphate↗

PubMed2005

Graft derived cells with double nuclei in the penumbral region of experimental brain trauma.

Recent in vitro studies showed that stem cells might fuse with mature cells or each other; however, there is no in vivo evidence for this phenomenon in the cerebral cortex. Our goal was to find evidence for cell fusion in a model of traumatic brain injury followed by grafting of embryonic cortical cells. Cold lesion protocol was applied to induce lesion of the motor cortex in adult male rats. Six days later we grafted a suspension of freshly isolated rat brain cortical cells of early embryonic stage (E14) into the penumbra area of the lesion. The grafted cell nuclei were labelled with bromodeoxyuridine (BrDU). Six days after transplantation 4,328 BrDU positive cells were observed in nine animals. 89.5% of these cells had cytoplasmic staining probably representing dead or phagocyted grafted cells. Ten percent of surviving BrDU positive cells had only one BrDU positive nucleus and negative cytoplasm, while 0.5% had two distinct nuclei, one was unlabelled and one was BrDU positive. These cells were similar in appearance and size to the astrocytes in the vicinity and expressed the astocyte specific glial fibrillaly acidic protein. Thus, these cells showed a possible sign of cell fusion in the penumbral region of the injured brain.

Animals↗

PubMed2005

Urotensin-II is a nitric oxide-dependent vasodilator in the pial arteries of the newborn pig.

Urotensin-II (UT-II) is a small circular peptide and is described as the most potent endogenous vasoconstrictor in various vascular beds. However, the in vivo effects of UT-II can be either vasoconstriction or vasodilation depending on the species and the tissue investigated. The present study sought to characterize the vasoactive effect of UT-II in the piglet cerebral circulation in vivo. Pial arteries of 99 +/- 6 microm were visualized with intravital microscopy through a closed cranial window in anesthetized newborn piglets. Topical application of UT-II elicited a weak dose-dependent vasodilation of the arteries (0.001 microM: 3 +/- 3 microm, 0.1 microM: 10 +/- 5 microm, 10 microM: 14 +/- 7 microm). Smaller arteries with an initial diameter below 100 microm showed minimal or no vasodilation, while larger arteries between 100 and 120 microm had a pronounced dose-dependent effect. Systemic application of 15 mg/kg Nomega-nitro-L-arginine-methyl ester (L-NAME) completely inhibited the vasodilation. We conclude that UT-II, in contrast to most other vascular beds, is a weak NO-dependent vasodilator in the piglet pial vasculature.

Administration, Topical↗

PubMed2005

Impaired endothelin-induced vasoconstriction in coronary arteries of Zucker obese rats is associated with uncoupling of [Ca2+]i signaling.

Although insulin resistance (IR) is a major risk factor for coronary artery disease, little is known about the regulation of coronary vascular tone in IR by endothelin-1 (ET-1). We examined ET-1 and PGF(2alpha)-induced vasoconstriction in isolated small coronary arteries (SCAs; approximately 250 microM) of Zucker obese (ZO) rats and control Zucker lean (ZL) rats. ET-1 response was assessed in the absence and presence of endothelin type A (ET(A); BQ-123), type B (ET(B); BQ-788), or both receptor inhibitors. ZO arteries displayed reduced contraction to ET-1 compared with ZL arteries. In contrast, PGF(2alpha) elicited similar vasoconstriction in both groups. ET(A) inhibition diminished the ET-1 response in both groups. ET(B) inhibition alone or in combination with ET(A) blockade, however, restored the ET-1 response in ZO arteries to the level of ZL arteries. Similarly, inhibition of endothelial nitric oxide (NO) synthase with N(omega)-nitro-l-arginine methyl ester (l-NAME) enhanced the contraction to ET-1 and abolished the difference between ZO and ZL arteries. In vascular smooth muscle cells from ZO, ET-1-induced elevation of myoplasmic intracellular free calcium concentration ([Ca2+]i) (measured by fluo-4 AM fluorescence), and maximal contractions were diminished compared with ZL, both in the presence and absence of l-NAME. However, increases in [Ca2+]i elicited similar contractions of the vascular smooth muscle cells in both groups. Analysis of protein and total RNA from SCA of ZO and ZL revealed equal expression of ET-1 and the ET(A) and ET(B) receptors. Thus coronary arteries from ZO rats exhibit reduced ET-1-induced vasoconstriction resulting from increased ET(B)-mediated generation of NO and diminished elevation of myoplasmic [Ca2+]i.

Animals↗

PubMed2005

Effects of LPS stimulation on the expression of prostaglandin carriers in the cells of the blood-brain and blood-cerebrospinal fluid barriers.

Prostaglandins produced in cerebral endothelial cells (CECs) are the final signal transduction mediators from the periphery to the brain during fever response. However, prostaglandins are organic anions at physiological pH, and they enter cells poorly using simple diffusion. Several transporters have been described that specifically transport prostaglandins across cell membranes. We examined the expression of the two principal prostaglandin carriers, prostaglandin transporter (PGT), and multidrug resistance-associated protein 4 (MRP4) in cells of the blood-brain barrier and in choroid epithelial cells in vitro as well as in vivo in rat brain in control conditions and after lipopolysaccharide (LPS) challenge. We detected PGT in primary cultures of rat CECs, astrocytes, pericytes, and choroid epithelial cells. LPS stimulation had no effect on the expression level of PGT in these cells; however, after LPS stimulation the polarized, dominantly luminal, expression pattern of PGT significantly changed. MRP4 is also expressed in CECs, and its level was not influenced by LPS treatment. In rat brain, PGT was highly expressed in the supraoptic and paraventricular nuclei of the hypothalamus, in the ependymal cell layer of the third ventricle, and in the choroid plexus. LPS treatment increased the expression of PGT in the supraoptic and paraventricular nuclei. Our results suggest that PGT and MRP4 likely play a role in transporting prostaglandins through the blood-brain and blood-cerebrospinal fluid barriers and may be involved in the maintenance of prostaglandin homeostasis in the brain and in the initiation of fever response.

Animals↗

PubMed2005

Rosuvastatin improves cerebrovascular function in Zucker obese rats by inhibiting NAD(P)H oxidase-dependent superoxide production.

Insulin-resistance induces cerebrovascular dysfunction and increases the risk for stroke. We investigated whether rosuvastatin (RSV), a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, can reverse reduced cerebrovascular responsiveness in insulin-resistant rats. Dilator responses of the basilar artery (BA) were examined after 1-day or 4-wk RSV (2 mg.kg(-1).day(-1)) treatment in anesthetized 12-wk-old insulin-resistant Zucker obese (ZO) and lean (ZL) rats by using a cranial window preparation. Vehicle-treated ZO rats had significantly higher fasting insulin, total cholesterol (TC), and triglyceride (TG) levels compared with ZL rats. In addition, in the ZO rats, dilator responses of the BA to acetylcholine, iloprost, cromakalim, and potassium chloride were significantly reduced when compared with ZL rats. One-day RSV treatment improved dilator responses of the ZO BAs without altering lipid levels. Four-week RSV treatment lowered both TC and TG by 30% and also improved dilator responses of the ZO BAs, although without additional effects compared with the 1-day RSV treatment. NAD(P)H oxidase-dependent superoxide production was significantly higher in the cerebral arteries of vehicle-treated ZO rats compared with ZL rats, but both 1-day and 4-wk RSV treatments normalized elevated superoxide levels in the ZO arteries. These findings demonstrate that RSV improves cerebrovascular function in insulin-resistance independently from its lipid-lowering effect by the inhibition of NAD(P)H oxidase.

Animals↗

PubMed2005

Cortical spreading depression (CSD)-induced tolerance to transient focal cerebral ischemia in halothane anesthetized rats is affected by anesthetic level but not ATP-sensitive potassium channels.

We investigated the participation of ATP-sensitive potassium (K(ATP)) channels, adenosine A1 receptors, and the effects of different levels of halothane anesthesia in the development of CSD-induced ischemic tolerance. To elicit CSD, 0.5 M KCl was applied for 2 h to the right hemisphere of halothane anesthetized male Wistar rats. The inhalation concentration of halothane during CSD was maintained at 0.5% (n = 8), 1.0% (n = 8), or 2.0% (n = 8). For control animals, saline was applied instead of KCl (n = 8). To inhibit K(ATP) channels or adenosine A1 receptors, glibenclamide (0.1 mg/kg icv; n = 8), 5-hydroxydeconaoate (5-HD; 100 mg/kg ip; n = 12), or 8-Cyclopentyl-1, 3-dipropylxanthine (DPCPX) (1.0 mg/kg ip; n = 8) was applied before preconditioning during 1.0% halothane anesthesia. Temporary occlusion (120 min) of the right middle cerebral artery was induced 4 days after preconditioning and the infarct volume was measured. Preconditioning elicited under 1.0% halothane reduced cortical infarct volume from 277 +/- 15 mm3 in the control group to 159 +/- 14 mm3 in the CSD group (mean +/- SEM, P < 0.05). In contrast, CSD induced during inhalation of 0.5% or 2.0% halothane did not confer ischemic tolerance. The reduction in infarct area with CSD during inhalation of 1% halothane was not changed in animals treated with glibenclamide or 5-HD or DPCPX. These results uncover a crucial role of halothane level but not of K(ATP) channels or adenosine A1 receptors in the preconditioning effects of CSD.

ATP-Binding Cassette Transporters↗

PubMed2005

Insulin resistance does not impair contractile responses of cerebral arteries.

Insulin resistance (IR) impairs endothelium-mediated vasodilation in cerebral arteries as well as K+ channel function in vascular smooth muscle. Peripheral arteries also show an impaired endothelium-dependent vasodilation in IR and concomitantly show an enhanced contractile response to endothelin-1 (ET-1). However, the contractile responses of the cerebral arteries in IR have not been examined systematically. This study examined the contractile responses of pressurized isolated middle cerebral arteries (MCAs) in fructose-fed IR and control rats. IR MCAs showed no difference in pressure-mediated (80 mmHg) vasoconstriction compared to controls, either in time to develop spontaneous tone (control: 61+/-3 min, n=30; IR: 63+/-2 min, n=26) or in the degree of that tone (control: 60 min: 33+/-2%, n=22 vs. IR 60 min: 34+/-3%, n=17). MCAs treated with ET-1 (10(-8.5) M) constrict similarly in control (53+/-3%, n=14) and IR (53+/-3%, n=14) arteries. Constrictor responses to U46619 (10(-6) M) are also similar in control (48+/-9%, n=8) and IR (42+/-5%, n=6) MCAs as are responses to extraluminal uridine 5'-triphosphate (UTP; 10(-4.5) M) (control: 35+/-7%, n=11 vs. IR: 38+/-3%, n=10). These findings demonstrate that constrictor responses remain intact in IR despite a selective impairment of dilator responses and endothelial and vascular smooth muscle K+ channel function in cerebral arteries. Thus, it appears that the increased susceptibility to cerebrovascular abnormalities associated with IR and diabetes (including cerebral ischemia, stroke, vertebrobasilar transient ischemic attacks) is not due to an enhanced vasoreactivity to constrictor agents.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2005

Autocrine peptide mediators of cerebral endothelial cells and their role in the regulation of blood-brain barrier.

A unique feature of cerebral endothelial cells (CECs) is the formation of the blood-brain barrier (BBB), which contributes to the stability of the brain microenvironment. CECs are capable of producing several substances mediating endothelium-dependent vasorelaxation or vasoconstriction, regulating BBB permeability, and participating in the regulation of cell-cell interactions during inflammatory and immunological processes. The chemical nature of these mediators produced by CECs ranges from gaseous anorganic molecules (e.g. nitric oxide) through lipid mediators (e.g. prostaglandins) to peptides. Peptide mediators are a large and diverse family of bioactive molecules which can elicit multiple effects on cerebral endothelial functions. In this review, we summarize current knowledge of peptide mediators produced by CECs, such as adrenomedullin, angiotensin, endothelin and several others and their role in the regulation of BBB functions.

Animals↗

PubMed2005

Adrenomedullin protects rat cerebral endothelial cells from oxidant damage in vitro.

Increased permeability and reduced cerebral endothelial cell (CEC) viability induced by oxidative stress are the hallmarks of the blood-brain barrier disruption. In our experiments hydrogen peroxide (H2O2, 0.5 mM) induced a continuous decrease of the transendothelial electrical resistance (TEER) and resulted in intercellular gap formations in cultured rat CECs. Adrenomedullin (AM) increased TEER, enhanced peripheral localization of F-actin bands and attenuated the increased permeability induced by H2O2. Furthermore, AM treatment preserved mitochondrial membrane potential, attenuated cytochrome c release, and consequently improved CEC viability in H2O2 treated cultures. These results suggest that AM treatment protects CECs against oxidative injury.

Actins↗