Gap analysis of future employee and employer on soft skills

BACKGROUND: Soft skills have become more necessary than ever in today’s labour market, and their development has become an increasingly key area for companies’ HR departments. Employees with the soft skills required for a given job can perform the tasks assigned to them more efficiently and successfully, therefore all those involved in the process can consider the completion of the task as a positive experience. By strengthening the employees’ soft skills, companies can improve their corporate culture, their market performance and thus their competitiveness. METHODS: The authors conducted a multi-year research in Hungary, the first part of which was a quantitative study to analyse the soft skills of young people leaving school, their awareness of employers’ expectations and the opportunities and tools they consider useful for developing these skills. The second part of the research involved the other side, i.e. the employers, to assess their expectations of the prospective employees’ soft skills and to explore the development opportunities that employers provide to strengthen these skills. RESULTS: The results of the two questionnaire surveys confirmed that both sides are aware of the soft skills needed in the labour market, although the market participants are not always in agreement about these needs. However, the development of skills, even though they enhance the market competitiveness of the employee and the employer, is not really in line with market expectations.

Cerebral microcirculatory responses of insulin-resistant rats are preserved to physiological and pharmacological stimuli

OBJECTIVE

Previously, we have shown that IR impairs the vascular reactivity of the major cerebral arteries of ZO rats prior to the occurrence of Type-II diabetes mellitus. However, the functional state of the microcirculation in the cerebral cortex is still being explored.

METHODS

We tested the local CoBF responses of 11-13-week-old ZO (n = 31) and control ZL (n = 32) rats to several stimuli measured by LDF using a closed cranial window setup.

RESULTS

The topical application of 1-100 μm bradykinin elicited the same degree of CoBF elevation in both ZL and ZO groups. There was no significant difference in the incidence, latency, and amplitude of the NMDA-induced CSD-related hyperemia between the ZO and ZL groups. Hypercapnic CoBF response to 5% carbon-dioxide ventilation did not significantly change in the ZO compared with the ZL. Topical bicuculline-induced cortical seizure was accompanied by the same increase of CoBF in both the ZO and ZL at all bicuculline doses.

CONCLUSIONS

CoBF responses of the microcirculation are preserved in the early period of the metabolic syndrome, which creates an opportunity for intervention to prevent and restore the function of the major cerebral vascular beds.

Depolarization of mitochondria in endothelial cells promotes cerebral artery vasodilation by activation of nitric oxide synthase

OBJECTIVE

Mitochondrial depolarization after ATP-sensitive potassium channel activation has been shown to induce cerebral vasodilation by the generation of calcium sparks in smooth muscle. It is unclear, however, whether mitochondrial depolarization in endothelial cells is capable of promoting vasodilation by releasing vasoactive factors. Therefore, we studied the effect of endothelial mitochondrial depolarization by mitochondrial ATP-sensitive potassium channel activators, BMS-191095 (BMS) and diazoxide, on endothelium-dependent vasodilation.

APPROACH AND RESULTS

Diameter studies in isolated rat cerebral arteries showed BMS- and diazoxide-induced vasodilations that were diminished by endothelial denudation. Mitochondrial depolarization-induced vasodilation was reduced by inhibition of mitochondrial ATP-sensitive potassium channels, phosphoinositide-3 kinase, or nitric oxide synthase. Scavenging of reactive oxygen species, however, diminished vasodilation induced by diazoxide, but not by BMS. Fluorescence studies in cultured rat brain microvascular endothelial cells showed that BMS elicited mitochondrial depolarization and enhanced nitric oxide production; diazoxide exhibited largely similar effects, but unlike BMS, increased mitochondrial reactive oxygen species production. Measurements of intracellular calcium ([Ca(2+)]i) in cultured rat brain microvascular endothelial cells and arteries showed that both diazoxide and BMS increased endothelial [Ca(2+)]i. Western blot analyses revealed increased phosphorylation of protein kinase B and endothelial nitric oxide synthase (eNOS) by BMS and diazoxide. Increased phosphorylation of eNOS by diazoxide was abolished by phosphoinositide-3 kinase inhibition. Electron spin resonance spectroscopy confirmed vascular nitric oxide generation in response to diazoxide and BMS.

CONCLUSIONS

Pharmacological depolarization of endothelial mitochondria promotes activation of eNOS by dual pathways involving increased [Ca(2+)]i as well as by phosphoinositide-3 kinase-protein kinase B-induced eNOS phosphorylation. Both mitochondrial reactive oxygen species-dependent and -independent mechanisms mediate activation of eNOS by endothelial mitochondrial depolarization.

N-methyl-D-aspartate induces cortical hyperemia through cortical spreading depression-dependent and -independent mechanisms in rats

OBJECTIVE

N-methyl-d-aspartate (NMDA) is a powerful cerebrovascular dilator in vivo. Cortical spreading depression (CSD) has recently been shown to contribute to the pial arteriolar dilation in mice. Our main aim was to examine the participation of CSD in the overall cerebrovascular response to NMDA in the rat.

METHODS

Anesthetized Wistar rats (eight weeks old) were equipped with a closed cranial window to allow topical application of NMDA (10(-5)-10(-3) M) to the parietal cortex. Cortical blood flow (CoBF) under and outside the cranial window was simultaneously monitored by using a two-channel laser-Doppler flowmeter. CSDs were detected by recording the changes in the cortical DC potential.

RESULTS

Concentrations of 10(-4) and 10(-3) M of NMDA evoked single CSDs associated with rapid, transient hyperemia, followed by a sustained, but reduced, increase in CoBF. The latency and magnitude of the CoBF responses were dose dependent. The higher dose resulted in shorter latency (100+/-5* vs. 146+/-11 seconds, *P<0.05; mean+/-standard error of the mean) and larger overall flow response (77+/-12* vs. 28+/-3% from baseline) under, but not outside, the cranial window.

CONCLUSIONS

NMDA elicits dose-dependent increases in CoBF that are composed of CSD-dependent and -independent components in rats.

Cerebrovascular responses to insulin in rats

Effects of insulin on cerebral arteries have never been examined. Therefore, we determined cerebrovascular actions of insulin in rats. Both PCR and immunoblot studies identified insulin receptor expression in cerebral arteries and in cultured cerebral microvascular endothelial cells (CMVECs). Diameter measurements (% change) of isolated rat cerebral arteries showed a biphasic dose response to insulin with an initial vasoconstriction at 0.1 ng/mL (-9.7%+/-1.6%), followed by vasodilation at 1 to 100 ng/mL (31.9%+/-1.4%). Insulin also increased cortical blood flow in vivo (30%+/-8% at 120 ng/mL) when applied topically. Removal of reactive oxygen species (ROS) abolished the vasoconstriction to insulin. Endothelial denudation, inhibition of K(+) channels, and nitric oxide (NO) synthase, all diminished insulin-induced vasodilation. Inhibition of cytochrome P450 enhanced vasodilation in endothelium-intact arteries, but promoted vasoconstriction after endothelial denudation. Inhibition of cyclooxygenase abolished vasoconstriction and enhanced vasodilation to insulin in all arteries. Inhibition of endothelin type A receptors enhanced vasodilation, whereas endothelin type B receptor blockade diminished vasodilation. Insulin treatment in vitro increased Akt phosphorylation in cerebral arteries and CMVECs. Fluorescence studies of CMVECs showed that insulin increased intracellular calcium and enhanced the generation of NO and ROS. Thus, cerebrovascular responses to insulin were mediated by complex mechanisms originating in both the endothelium and smooth muscle.

Rosuvastatin induces delayed preconditioning against L-glutamate excitotoxicity in cultured cortical neurons

We tested whether rosuvastatin (RST) protected against excitotoxic neuronal cell death in rat primary cortical neuronal cultures. L-glutamate (200 microM, 1h) reduced neuronal viability (% of naive controls, mean+/-SEM, n=8-32, *p<0.05) from 100+/-2% to 60+/-1%*, but pretreatment with RST (0.5 microM, 3 days) increased survival to 88+/-2%*. RST-induced neuroprotection was not affected by co-application with mevalonate (10 microM), although the same dose of mevalonate fully prevented the neurotoxic effects of a high dose (20 microM) of RST. RST (0.5 microM) pretreatment did not affect mitochondrial membrane potential or superoxide anion levels in quiescent neurons. However, RST pretreatment blunted elevations in free intracellular Ca(2+) and reduced increases in superoxide anion levels following glutamate exposure. Manganese superoxide dismutase (SOD), copper-zinc SOD, catalase, and reduced glutathione levels were unaffected by RST pretreatment. In contrast, acute, one time RST application did not affect either baseline or L-glutamate-induced increases in superoxide levels. In summary, three-day RST pretreatment induces resistance to the excitotoxic effect of L-glutamate in cultured neurons apparently by a mechanism that is independent of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibition. The delayed neuroprotection by RST against excitotoxicity does not involve sustained mitochondrial depolarization or superoxide anion production as initiating events, although it is associated with reduced Ca(2+) influx and superoxide anion production upon L-glutamate challenge.

Immediate neuronal preconditioning by NS1619

The objectives of our present experiments were to determine whether the BK(Ca) channel agonist NS1619 is able to induce immediate preconditioning in cultured rat cortical neurons and to elucidate the role of BK(Ca) channels in the initiation of immediate preconditioning. NS1619 depolarized mitochondria and increased reactive oxygen species (ROS) generation, but neither of these effects was inhibited by BK(Ca) channel antagonists. NS1619 also activated the extracellular signal-regulated kinase signaling pathways. One-hour treatment with NS1619 induced immediate protection against glutamate excitotoxicity (viability 24 h after glutamate exposure: control, 58.45+/-0.95%; NS1619 50 microM, 78.99+/-0.90%; NS1619 100 microM, 86.89+/-1.20%; NS1619 150 microM, 93.23+/-1.23%; mean+/-SEM; p<0.05 vs. control; n=16-32). Eliminating ROS during the preconditioning phase effectively blocked the development of cytoprotection. In contrast, the BK(Ca) channel blockers iberiotoxin and paxilline, the phosphoinositide 3-kinase inhibitor wortmannin, the protein kinase C blocker chelerythrine, and the mitogen activated protein kinase antagonist PD98059 were unable to antagonize the immediate neuroprotective effect. Finally, preconditioning with NS1619 reduced the calcium load and ROS surge upon glutamate exposure and increased superoxide dismutase activity. Our results indicate that NS1619 is an effective inducer of immediate neuronal preconditioning, but the neuroprotective effect is independent of the activation of BK(Ca) channels.

Neuroprotective effect of adenoviral catalase gene transfer in cortical neuronal cultures

Reduced availability of reactive oxygen species is a key component of neuroprotection against various toxic stimuli. Recently we showed that the hydrogen peroxide scavenger catalase plays a central role in delayed preconditioning induced by the mitochondrial ATP-sensitive potassium channel opener BMS-191095. The purpose of the experiments discussed here was to investigate the neuroprotective effect of catalase in vitro using a recombinant adenoviral catalase gene transfer protocol. To induce catalase overexpression, cultured rat cortical neurons were infected with the adenoviral vector Ad5CMVcatalase and control cells were incubated with Ad5CMVntLacZ for 24 h. Gene transfer effectively increased catalase protein levels and activity, but did not influence other antioxidants tested. Ad5CMVcatalase, with up to 10 plaque forming units (pfu) per neuron, did not affect cell viability under control conditions and did not protect against glutamate excitotoxicity or oxygen-glucose deprivation. In contrast, catalase overexpression conferred a dose-dependent protection against exposure to hydrogen peroxide (viability: control, 33.02+/-1.09%; LacZ 10 pfu/cell, 32.85+/-1.51%; catalase 1 pfu/cell, 62.09+/-4.17%*; catalase 2 pfu/cell, 98.71+/-3.35%*; catalase 10 pfu/cell, 99.68+/-1.99%*; *p<0.05 vs. control; mean+/-SEM). Finally, the protection could be antagonized using the catalase inhibitor 3-aminotriazole. Our results support the view that enhancing cellular antioxidant capacity may play a crucial role in neuroprotective strategies.

Rosuvastatin induces delayed preconditioning against oxygen-glucose deprivation in cultured cortical neurons

We tested whether rosuvastatin (RST) protected against oxygen-glucose deprivation (OGD)-induced cell death in primary rat cortical neuronal cultures. OGD reduced neuronal viability (%naive controls, mean +/- SE, n = 24-96, P < 0.05) to 44 +/- 1%, but 3-day pretreatment with RST (5 microM) increased survival to 82 +/- 2% (P < 0.05). One-day RST treatment was not protective. RST-induced neuroprotection was abolished by mevalonate or geranylgeranyl pyrophosphate (GGPP), but not by cholesterol coapplication. Furthermore, RST-induced decreases in neuronal cholesterol levels were abolished by mevalonate but not by GGPP. Reactive oxygen species (ROS) levels were reduced in RST-preconditioned neurons after OGD, and this effect was also reversed by both mevalonate and GGPP. These data suggested that GGPP, but not cholesterol depletion, were responsible for the induction of neuroprotection. Therefore, we tested whether 3-day treatments with perillic acid, a nonspecific inhibitor of both geranylgeranyl transferase (GGT) GGT 1 and Rab GGT, and the GGT 1-specific inhibitor GGTI-286 would reproduce the effects of RST. Perillic acid, but not GGTI-286, elicited robust neuronal preconditioning against OGD. RST, GGTI-286, and perillic acid all decreased mitochondrial membrane potential and lactate dehydrogenase activity in the cultured neurons, but only RST and perillic acid reduced neuronal ATP and membrane Rab3a protein levels. In conclusion, RST preconditions cultured neurons against OGD via depletion of GGPP, leading to decreased geranylgeranylation of proteins that are probably not isoprenylated by GGT 1. Reduced neuronal ATP levels and ROS production after OGD may be directly involved in the mechanism of neuroprotection.

Cerebromicrovascular endothelial cells are resistant to L-glutamate

Cerebral microvascular endothelial cells (CMVECs) have recently been implicated as targets of excitotoxic injury by l-glutamate (l-glut) or N-methyl-d-aspartate (NMDA) in vitro. However, high levels of l-glut do not compromise the function of the blood-brain barrier in vivo. We sought to determine whether primary cultures of rat and piglet CMVECs or cerebral microvascular pericytes (CMVPCs) are indeed sensitive to l-glut or NMDA. Viability was unaffected by 8-h exposure to 1-10 mM l-glut or NMDA in CMVECs or CMVPCs isolated from both species. Furthermore, neither 1 mM l-glut nor NMDA augmented cell death induced by 12-h oxygen-glucose deprivation in rat CMVECs or by 8-h medium withdrawal in CMVPCs. Additionally, transendothelial electrical resistance of rat CMVEC-astrocyte cocultures or piglet CMVEC cultures were not compromised by up to 24-h exposure to 1 mM l-glut or NMDA. The Ca(2+) ionophore calcimycin (5 microM), but not l-glut (1 mM), increased intracellular Ca(2+) levels in rat CMVECs and CMVPCs assessed with fluo-4 AM fluorescence and confocal microscopy. CMVEC-dependent pial arteriolar vasodilation to hypercapnia and bradykinin was unaffected by intracarotid infusion of l-glut in anesthetized piglets by closed cranial window/intravital microscopy. We conclude that cerebral microvascular cells are insensitive and resistant to glutamatergic stimuli in accordance with their in vivo role as regulators of potentially neurotoxic amino acids across the blood-brain barrier.

Delayed neuronal preconditioning by NS1619 is independent of calcium activated potassium channels

1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS1619), a potent activator of the large conductance Ca2+ activated potassium (BK(Ca)) channel, has been demonstrated to induce preconditioning (PC) in the heart. The aim of our study was to test the delayed PC effect of NS1619 in rat cortical neuronal cultures against oxygen-glucose deprivation, H2O2, or glutamate excitotoxicity. We also investigated its actions on reactive oxygen species (ROS) generation, and on mitochondrial and plasma membrane potentials. Furthermore, we tested the activation of the phosphoinositide 3-kinase (PI3K) signaling pathway, and the effect of NS1619 on caspase-3/7. NS1619 dose-dependently protected the cells against the toxic insults, and the protection was completely blocked by a superoxide dismutase mimetic and a PI3K antagonist, but not by BK(Ca) channel inhibitors. Application of NS1619 increased ROS generation, depolarized isolated mitochondria, hyperpolarized the neuronal cell membrane, and activated the PI3K signaling cascade. However, only the effect on the cell membrane potential was antagonized by BK(Ca) channel blockers. NS1619 inhibited the activation of capase-3/7. In summary, NS1619 is a potent inducer of delayed neuronal PC. However, the neuroprotective effect seems to be independent of cell membrane and mitochondrial BK(Ca) channels. Rather it is the consequence of ROS generation, activation of the PI3K pathway, and inhibition of caspase activation.

Systemic administration of diazoxide induces delayed preconditioning against transient focal cerebral ischemia in rats

Diazoxide is the prototypical opener of mitochondrial ATP-sensitive potassium channels (mitoK(ATP)) and protects neurons in vivo and in vitro against chemical and anoxic stresses. While we have previously shown that diazoxide administration induces acute preconditioning against transient cerebral ischemia in rats, the potential for delayed preconditioning of diazoxide has not been examined. The purpose of this study was to determine whether diazoxide promotes delayed preconditioning following 90 min of middle cerebral artery occlusion (MCAO) in male Wistar rats. Diazoxide (10 mg/kg) or vehicle was injected intraperitoneally 24 h before MCAO. Infarct volumes were measured 72 h after reperfusion. In animals anesthetized with halothane, treatment with diazoxide exhibited a 35% reduction (48.3+/-3.0% to 31.3+/-4.8%) and 18% reduction (35.1+/-2.2% to 28.9+/-2.1%) in cortical and subcortical infarct volumes, respectively. Administration of the mitoK(ATP) blocker 5-hydroxydecanoate attenuated this beneficial effect. In contrast, diazoxide did not induce delayed preconditioning in isoflurane-anesthetized rats. These findings support the concept that diazoxide produces delayed preconditioning via mitoK(ATP) activation but that physiological status can affect induction of preconditioning.

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

Neuronal preconditioning with the antianginal drug, bepridil

It has recently been shown that the antianginal drug bepridil (BEP) activates mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels and thus confers cardioprotection. Our aim was to investigate whether BEP could induce preconditioning in cultured rat cortical neurons. Although BEP depolarized isolated and in situ mitochondria and increased reactive oxygen species generation, no acute protection was observed. However, a 3-day BEP-treatment elicited dose-dependent delayed neuroprotection against 180 min of oxygen-glucose deprivation (cell viability: untreated, 52.5 +/- 0.85%; BEP 1 micromol/L, 59.6 +/- 1.53%*; BEP 2.5 micromol/L, 71.9 +/- 1.23%*; BEP 5 micromol/L, 95.3 +/- 0.89%*; mean +/- SEM; *p < 0.05 vs. untreated) and 60 min of glutamate excitotoxicity (200 micromol/L; cell viability: untreated, 54.1 +/- 0.69%; BEP 1 micromol/L, 61.2 +/- 1.19%*; BEP 2.5 micromol/L, 78.1 +/- 1.67%*; BEP 5 micromol/L, 91.2 +/- 1.20%*; mean +/- SEM; *p < 0.05 vs. untreated), and inhibited the reactive oxygen species surge upon glutamate exposure. The protection was antagonized with co-application of the superoxide dismutase mimetic M40401, but not with reduced glutathione, catalase, or with the mitoK(ATP) blocker 5-hydroxydecanoate. Furthermore, BEP treatment resulted in increased levels of phosphorylated protein kinase C, manganese-dependent superoxide dismutase, glutathione peroxidase, and Bcl-2. Our results indicate that BEP induces delayed neuronal preconditioning which is dependent on superoxide generation but perhaps not on direct mitoK(ATP) activation.

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.

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.

Pituitary adenylate cyclase-activating polypeptide inhibits the cyclooxygenase pathway of rat cerebral microvessels

The presence of nerve endings containing pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) around cerebral microvessels suggests that these peptides have regulatory roles in the cerebral microcirculation. Prostanoids synthesized by the cerebrovascular endothelium have a determining role in the regulation of the brain circulation. In the present study, the effects of PACAP and VIP on the cyclooxygenase pathway of cerebral microvessels were investigated. The isolated microvessels were incubated with 1-14C-arachidonic acid and different concentrations of the peptides. The prostanoids formed were separated by means of overpressure thin-layer chromatography, and were quantitatively determined by liquid scintillation. Higher concentrations (10-7 and 10-6 mol L-1) of PACAP significantly inhibited the activity of the cyclooxygenase pathway, whereas VIP had no significant effect on it. As regards the cyclooxygenase metabolites, the syntheses of thromboxane A2 and prostaglandin D2 were inhibited significantly. PACAP and VIP are known to increase the intracellular cAMP level in the cerebral microvessels and in the present experiments the protein kinase A inhibitor H-89 attenuated the effect of PACAP on prostanoid synthesis. It is concluded that the cyclooxygenase pathway of rat cerebral microvessels is more sensitive to PACAP than to VIP. The inhibitory effect of PACAP on prostanoid synthesis is mediated via a cAMP-dependent pathway. By inhibiting the formation of vasoactive prostanoids, PACAP can decrease the vasoreactivity of the microvessels.