Netrin-1 and multiple sclerosis: a new biomarker for neuroinflammation?

BACKGROUND AND PURPOSE: Netrin-1, an axon guidance protein, reduces serum levels of pro-inflammatory mediators and stabilizes the blood-brain barrier limiting the entrance of immune cells into the central nervous system. The aim was to investigate its presence in the experimental autoimmune encephalomyelitis (EAE) model and in multiple sclerosis (MS) patients with and without clinical activity. METHODS: Netrin-1 levels were evaluated in EAE mouse tissues. Afterwards, serum netrin-1 was cross-sectionally quantified in 90 patients with different MS phenotypes and 30 control subjects. An additional group of 10 relapsing-remitting MS (RRMS) patients was longitudinally evaluated throughout a relapse (RRMSr) with an interval of 60 days. Tumour necrosis factor α (TNFα), a reference inflammatory cytokine, and netrin-1 were quantified by enzyme-linked immunosorbent assay. RESULTS: Experimental autoimmune encephalomyelitis mice showed significantly lower netrin-1 levels and higher TNFα amounts in sera, spinal cord and cerebella than healthy control mice. MS patients showed significantly lower serum netrin-1 levels than controls (511.62 ± 209.30 and 748.32 ± 103.24 pg/ml, respectively; P ≤ 0.005). The lowest protein levels were found in RRMSr, remaining significantly lower throughout the relapse. TNFα serum concentrations were higher in MS patients compared to controls, and negatively correlated with netrin-1 levels (r = -0.3734, P ≤ 0.0001). CONCLUSIONS: Netrin-1 decreased in EAE and in MS patients, mainly during relapse, suggesting an anti-inflammatory role of netrin-1. Further research should be performed in a larger cohort of patients to validate netrin-1 as a biomarker of MS inflammatory activity.

Oleanolic acid modulates the immune-inflammatory response in mice with experimental autoimmune myocarditis and protects from cardiac injury. Therapeutic implications for the human disease.

Myocarditis and dilated cardiomyopathy (DCM) are inflammatory diseases of the myocardium, for which appropriate treatment remains a major clinical challenge. Oleanolic acid (OA), a natural triterpene widely distributed in food and medicinal plants, possesses a large range of biological effects with beneficial properties for health and disease prevention. Several experimental approaches have shown its cardioprotective actions, and OA has recently been proven effective for treating Th1 cell-mediated inflammatory diseases; however, its effect on inflammatory heart disorders, including myocarditis, has not yet been addressed. Therefore, the present study was undertaken to determine the effectiveness of OA in prevention and treatment of experimental autoimmune myocarditis (EAM). The utility of OA was evaluated in vivo through their administration to cardiac α-myosin (MyHc-α614-629)-immunized BALB/c mice from day 0 or day 21 post-immunization to the end of the experiment, and in vitro through their addition to stimulated-cardiac cells. Prophylactic and therapeutic administration of OA dramatically decreased disease severity: the heart weight/body weight ratio as well as plasma levels of brain natriuretic peptide and myosin-specific autoantibodies production were significantly reduced in OA-treated EAM animals, compared with untreated ones. Histological heart analysis showed that OA-treatment diminished cell infiltration, fibrosis and dystrophic calcifications. OA also decreased proliferation of cardiac fibroblast in vitro and attenuated calcium and collagen deposition induced by relevant cytokines of active myocarditis. Furthermore, in OA-treated EAM mice the number of Treg cells and the production of IL-10 and IL-35 were markedly increased, while proinflammatory and profibrotic cytokines were significantly reduced. We demonstrate that OA ameliorates both developing and established EAM by promoting an antiinflammatory cytokine profile and by interfering with the generation of cardiac-specific autoantibodies, as well as through direct protective effects on cardiac cells. Therefore, we envision this natural product as novel helpful tool for intervention in inflammatory cardiomyopathies including myocarditis.

[Patient participation through active listening. About the remodeling of an extractions service]. / Participación del paciente a través de la escucha activa. A propósito de la remodelación de un servicio de extracciones.

BACKGROUND AND OBJECTIVE: From listening to patients there arises the possibility of improving both the care and the health infrastructure that users frequent. Our purpose of study was to explore the perception of users about the means and the care received involved in a hospital service through active listening, and to evaluate the satisfaction perceived after the opening of the renovated area. METHODS: A mixed methodology evaluative investigation was carried out within the context of the Extraction Service of the Costa del Sol Hospital, using qualitative methodology to assess the perception of users, and quantitative methodology through a satisfaction survey to identify the change after remodeling of the area. RESULTS: Through a qualitative approach, improvements have been identified in terms of the internal and external infrastructure of the center, highlighting the need to personalize spaces depending on the profile of the patient attended. In evaluating the impact after remodeling the area, patients have a higher overall satisfaction both from the healthcare professionals who attend them and from the healthcare center. CONCLUSIONS: Through the use of a mixed methodology, useful information has been incorporated for a project to improve a hospital infrastructure, and a subsequent evaluation of the positive impact on the satisfaction perceived by users after remodeling.

Occupancy of platelet receptors for platelet-activating factor in patients with septicemia.

The possible involvement of platelet-activating factor (PAF) in the pathogenesis of endotoxemia, was investigated by using a binding assay to patients' platelets, complemented with the extraction and chemical characterization of PAF obtained from patients' platelets. Platelets from 12 human volunteers had 281 +/- 63 freely accessible high affinity binding sites (PAF-receptors) per platelet; whereas this number was of 49 +/- 37 PAF-receptors per platelet, n = 14 samples, P less than 0.01, in a group of 13 patients with positive blood culture. A group of patients with respiratory or cardiovascular disturbances and negative blood culture had 253 +/- 74, accessible receptors per platelet (n = 19 samples from 16 patients, P less than 0.01 as compared to septic patients, which was not significantly different when compared to control individuals). Patients with sepsis possessed significant amounts of PAF associated to their platelets, whereas this mediator could not be isolated from platelets of patients with respiratory or cardiovascular disturbances and negative blood culture, nor from platelets of control individuals. PAF was also assayed in whole blood samples and found at high concentrations in sepsis patients. These data indicate that occupancy of PAF receptors in combination with high amounts of platelet-associated PAF, is a common finding in patients with sepsis.

Cytosolic phospholipase A2 and the distinct transcriptional programs of astrocytoma cells.

Astrocytes constitute the most abundant cell type in the nervous system. Under physiological conditions, they respond to the stimuli to which neurons are also responsive. The use of astrocytoma cell lines with well-defined morphological and functional markers has been helpful for addressing the mechanisms of signal transduction that operate in the nervous system. On the basis of the effects produced by agonists of different types of receptor (muscarinic ACh receptors, thrombin receptors, phospholipases A2 receptors and tumor necrosis factor alpha receptors), several different transcriptional programs that involve the MAP kinase-cytosolic phospholipase A2 system and the transcription factor NF-kappaB have been described.

Modulation of lyso-platelet-activating factor: acetyl-CoA acetyltransferase from rat splenic microsomes. The role of calcium ions.

The enzyme lyso-platelet-activating factor: acetyl-CoA acetyltransferase (EC 2.3.1.67) was assayed in microsomal fractions from rat spleens. The addition of micromolar Ca2+ rapidly enhanced acetyltransferase activity and this activation was reversed by the addition of EGTA in excess of Ca2+. The effect of Ca2+ was on the apparent Km of the enzyme for the substrate acetyl-CoA without showing any significant effect on the Vmax of the acetylation reaction. When microsomes were isolated in the presence of 5 mM EGTA, to remove endogenous calmodulin, the same enhancing effect of Ca2+ on the acetylation reaction was observed. The addition of exogenous calmodulin to this preparation had no effect on the enzyme activity. Preincubation of spleen microsomes with the calmodulin inhibitor trifluoperazine decreased acetyltransferase in both the presence and the absence of Ca2+, indicating an effect of this drug independently of calmodulin. The addition of Mg-ATP to the assay mixture also had no effect on the acetylation reaction. These data suggest that Ca2+ modulates acetyltransferase activity from rat spleen microsomes by a mechanism that seems to be independent of calmodulin or protein phosphorylation.

Red wine intake but not other alcoholic beverages increases total antioxidant capacity and improves pro-inflammatory profile after an oral fat diet in healthy volunteers.

INTRODUCTION: Different alcoholic beverages exert different effects on inflammation and oxidative stress but these results are controversial and scanty in some aspects. We analyze the effect of different alcoholic beverages after a fat-enriched diet on lipid profile, inflammatory factors and oxidative stress in healthy people in a controlled environment. METHODS: We have performed a cross-over design in five different weeks. Sixteen healthy volunteers have received the same oral fat-enriched diet (1486kcal/m(2)) and a daily total amount of 16g/m(2) of alcohol, of different beverages (red wine, vodka, brandy or rum) and equivalent caloric intakes as sugar with water in the control group. We have measured the levels of serum lipids, high sensitivity C-reactive protein (hsCRP), tumor necrosis factor α (TNFα), interleukin 6 (IL-6), soluble phospholipase A2 (sPLA2), lipid peroxidation (LPO) and total antioxidant capacity (TAC). RESULTS: Red wine intake was associated with decreased of mean concentrations of hsCRP, TNFα and IL-6 induced by fat-enriched diet (p<0.05); nevertheless, sPLA2 concentrations were not significantly modified. After a fat-enriched diet added with red wine, TAC increased as compared to the same diet supplemented with rum, brandy, vodka or the control (water with sugar) (p<0.05). CONCLUSIONS: Moderate red wine intake, but not other alcoholic beverages, decreased pro-inflammatory factors and increased total antioxidant capacity despite a fat-enriched diet intake in healthy young volunteers.

Effect of 4-trifluoromethyl derivatives of salicylate on nuclear factor kappaB-dependent transcription in human astrocytoma cells.

1. The effect of two derivatives of salicylate, 2-hydroxy-4-trifluoromethylbenzoic acid (HTB) and 2-acetoxy-4-trifluoromethylbenzoic acid (triflusal), on the expression of several proteins displaying pro-inflammatory activities the regulation of which is associated to the transcription factor NF-kappaB, was assayed in the human astrocytoma cell line 1321N1. 2. Tumour necrosis factor-alpha (TNF-alpha) activated NF-kappaB as judged from both the appearance of kappaB-binding activity in the nuclear extracts, the degradation of IkappaB proteins in the cell lysates, and the activation of IkappaB kinases using an immunocomplex kinase assay with glutathione S-transferase (GST)-IkappaB proteins as substrates. 3. HTB up to 3 mM did not inhibit the nuclear translocation of NK-kappaB/Rel proteins as judged from electrophoretic mobility-shift assays; however, HTB inhibited the degradation of IkappaBbeta without significantly affecting the degradation of both IkappaBalpha and IkappaBepsilon. 4. In keeping with their inhibitory effect on IkappaBbeta degradation in the cell lysates, both HTB and triflusal inhibited the phosphorylation of GST-IkappaBbeta elicited by TNF-alpha, without affecting the phosphorylation of GST-IkappaBalpha. 5. The effect of both HTB and triflusal on kappaB-dependent trans-activation was studied by assaying the expression of both cyclo-oxygenase-2 (COX-2) and vascular cell adhesion molecule-1 (VCAM-1). HTB and triflusal inhibited in a dose-dependent manner the expression of COX-2 and VCAM-1 mRNA and the induction of COX-2 protein at therapeutically relevant concentrations. 6. These findings show the complexity of the biochemical mechanisms underlying the activation of NF-kappaB in the different cell types and extend the anti-inflammatory effects of HTB and triflusal to neural cells.

Antiepileptic drugs and atypical evolution of idiopathic partial epilepsy.

Six patients with classic benign epilepsy of childhood with centrotemporal spikes, treated with carbamazepine (four patients) or sodium valproate (two patients) evolved atypically because the epileptic disorder, diffusion of the electroencephalographic (EEG) discharges during wakefulness, and continuous spike-and-wave during slow sleep associated with severe neuropsychologic abnormalities worsened. These features appeared after a seizure-free interval varying for 2 weeks to 1 year 6 months after initiating therapy and remitted when the previous anticonvulsant drug was discontinued and either substituted with another drug or the patient was left without any treatment. Once the initial antiepileptic drug was discontinued and after a period roughly proportional to the duration of the clinical-EEG complication, the evolution of the patients' seizures was not unusual for this type of epilepsy, with patients eventually becoming free of both seizures and medication and reaching normal school achievement. The clinical complications cannot be attributed solely to the drugs. It must also be related to the underlying substract (i.e., the specific epileptic syndrome involved) that in some patients becomes susceptible to atypical evolution when either product is administered.

Synthesis of platelet-activating factor from human polymorphonuclear leukocytes: regulation and pharmacological approaches.

Human polymorphonuclears release a platelet-activating factor (PAF-acether) when challenged with various stimuli. PAF-acether is a mediator that is synthesized during cell activation in a process in which a phospholipase A2 and an acetyltransferase take part. These enzymes are finely regulated and accordingly PAF-acether release may be modulated. The authors have studied some of the transductory mechanisms which are triggered during cell stimulation and the effect of their pharmacological modulation on PAF-acether release. Theophylline, methylisobutylxanthine and dipyridamole, which block phosphodiesterase of cyclic nucleotides, induce a dose-dependent inhibition of PAF-acether release without affecting phagocytic uptake. Polyamines (dansylcadaverine, rimantadine and amantadine) reduced PAF-acether release and the phagocytic process in an order of potency similar to their ability to inhibit phospholipid methylation and the cholinephosphotransferase pathway. The calmodulin antagonist trifluoperazine induced a dose-dependent inhibition of PAF-acether release and acetyltransferase at concentrations from 10(-4) to 10(-5) M. Hence it appears that modulation of PAF-acether release can be obtained by different pharmacological blockades: phosphodiesterase of cyclic nucleotides, phospholipid metabolism and calcium-calmodulin.

[Bronchogenic carcinoma and human immunodeficiency virus infection]. / Carcinoma broncogénico e infección por el virus de la inmunodeficiencia humana.

The coexistence of bronchogenic carcinoma and human immunodeficiency virus is unusual. Patients are usually young former smokers and histopathologic type is most often adenocarcinoma. We describe two cases of bronchogenic carcinoma in HIV positive individuals.

[Opercular epileptic syndrome: an unusual form of benign partial epilepsy in childhood]. / El síndrome opercular epiléptico: una forma peculiar de epilepsia parcial benigna de la infancia con paroxismos rolándicos.

INTRODUCTION: Functional opercular syndrome in childhood is an exceptional form of presentation of benign partial epilepsy with centro-temporal rolandic spikes (BECRS). CLINICAL CASES: We studied the evolution of four patients, three of them followed for more than 15 years. Two were siblings, and their father suffered from BECRS with permanent language problems (verbal dyspraxia) and difficulty of protunding his tongue in adulthood. A third patient suffered benign familial neonatal convulsions (BFNC). In all four patients the actual illness begun as a BECRS with opercular troubles as an ictal phenomena. At about four years of age, the opercular disfunction became evident, with severe drooling, facial hypomobility and speech disturbance which waxed and vanished along weeks, months or years, apparently not ictal. Antiepileptic drugs not only were unable to control this situation but also, some of them, like carbamazepine, even worsened the opercular disfunction, increased the number of seizures and enhanced the neuropsychologic disfunction. Only clobazam could achieve the control on opercular disfunction. After 16 years, no further treatment was needed for all patients. There were some permanent sequelae, as speech and orolingual dyspraxia and different neuropsychologic problems. CONCLUSION: Of noteworth the best performance was attained by the patient treated with clobazam on monotherapy.

[Alterations of nuclear maturity in spermatozoids of males with antecedents of cryptorchidism]. / Alteraciones de la madurez nuclear en espermatozoides de varones con antecedentes de criptorquidia.

The association between infertility and cryptorchidism is an accepted fact, usually attributed to the oligozoosperm, asthenozoosperm or teratozoosperm presented in ejaculation products of males with this antecedent. The nuclear maturity in a sample of men with antecedents of cryptorchidism have been studied and these results have been compared to those of a control group. The results of this work show the deficient transformation of nuclear proteins to protamines in males with antecedents of cryptorchidism compared to the control group, due to the remaining of immature histones. Alterations of nuclear maturity able to contribute to the subfertility of these men were found in spermatozoids of adult males with antecedents of cryptorchidism.

Natural triterpenes modulate immune-inflammatory markers of experimental autoimmune encephalomyelitis: therapeutic implications for multiple sclerosis.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory demyelinating diseases that develop as a result of deregulated immune responses causing glial activation and destruction of CNS tissues. Oleanolic acid and erythrodiol are natural triterpenes that display strong anti-inflammatory and immunomodulatory activities. Oleanolic acid beneficially influences the course of established EAE. We now extend our previous observations to erythrodiol and address the efficacy of both compounds to protect against EAE, given under different regimens. EXPERIMENTAL APPROACH: The utility of both triterpenes in disease prevention was evaluated at a clinical and molecular level: in vivo through their prophylactic administration to myelin oligodendrocyte protein-immunized C57BL/6 mice, and in vitro through their addition to stimulated-BV2 microglial cells. KEY RESULTS: These triterpenes protected against EAE by restricting infiltration of inflammatory cells into the CNS and by preventing blood-brain barrier disruption. Triterpene-pretreated EAE-mice exhibited less leptin secretion, and switched cytokine production towards a Th2/regulatory profile, with lower levels of Th1 and Th17 cytokines and higher expression of Th2 cytokines in both serum and spinal cord. Triterpenes also affected the humoral response causing auto-antibody production inhibition. In vitro, triterpenes inhibited ERK and rS6 phosphorylation and reduced the proliferative response, phagocytic properties and synthesis of proinflammatory mediators induced by the addition of inflammatory stimuli to microglia. CONCLUSIONS AND IMPLICATIONS: Both triterpenes restricted the development of the characteristic features of EAE. We envision these natural products as novel helpful tools for intervention in autoimmune and neurodegenerative diseases including MS.

Biosynthesis of platelet-activating factor in human polymorphonuclear leukocytes. Involvement of the cholinephosphotransferase pathway in response to the phorbol esters.

The generation of platelet-activating factor (PAF) in response to complement-coated zymosan particles, ionophore A23187 and 12-O-tetradecanoylphorbol 13-acetate (TPA) was studied in human polymorphonuclear leukocytes (PMN). TPA was an active stimulator of PAF biosynthesis but showed a time course more protracted than that observed in response to other secretagogues. TPA was not found to activate acetyl-CoA:lyso-PAF acetyltransferase activity nor to significantly enhance the incorporation of either [3H] lyso-PAF or [3H]acetate into a lipid fraction co-migrating as PAF. To assess whether TPA could be a secretagogue that promotes the biosynthesis of PAF through the dithiothreitol-insensitive cholinephosphotransferase pathway, this enzymic activity was assayed in homogenates from PMN preincubated in the presence of several secretagogues. None of the agonists was found to enhance this enzyme activity. However, TPA did enhance the incorporation of [methyl-3H]choline and both alkyl- and acetyl-labeled 1-O-hexadecyl-2-acetyl-sn-glycerol into a lipid fraction co-migrating with PAF. This incorporation showed a time course parallel to that of the generation of PAF in response to TPA. Incubation of [methyl-3H]choline-labeled cells in the presence of 1-O-hexadecyl-2-acetyl-sn-glycerol caused an enhanced incorporation of the label into the fraction co-migrating as PAF, and this incorporation was synergistically enhanced by TPA. Pulse-chase experiments with choline showed that TPA caused an early accumulation of choline into phosphatidylcholine and PAF rather than into CDP-choline. The present data indicate that TPA is the only agonist that could initiate the biosynthesis of PAF in human PMN through the cholinephosphotransferase pathway and that this process of biosynthesis is regulated at an enzyme step other than dithiothreitol-insensitive cholinephosphotransferase.

Modulation of acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine (lyso-PAF) acetyltransferase in human polymorphonuclears. The role of cyclic AMP-dependent and phospholipid sensitive, calcium-dependent protein kinases.

In order to characterize the mechanism of activation of the enzyme 1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine:acetyl-CoA acetyltransferase (EC 2.3.1.67) which is the limiting step in the regulation of the synthesis of the potent inflammatory mediator 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; homogenates from human polymorphonuclear leukocytes were incubated in the presence of the catalytic subunit of cyclic AMP-dependent protein kinase and in the presence of a partially purified phospholipid sensitive, calcium-dependent protein kinase (PrKC). The first kinase was found to enhance up to 3-fold acetyltransferase activity in a dose- and time-dependent manner. In homogenates from PMN previously stimulated with complement-coated zymosan particles, the decay of acetyltransferase activity was partially prevented by the addition of soybean trypsin inhibitor and almost completely inhibited when the homogenates were supplemented with inhibitors of alkaline phosphatase such as 50 mM KF and 100 microM paranitrophenylphosphate. Under these conditions it was possible to initiate the decay of acetyltransferase activity by adding an excess of alkaline phosphatase. Preincubation of PMN with 12-O-tetradecanoylphorbol-13-acetate previous or simultaneously to the addition of ionophore A23187 reduced the increase in acetyltransferase produced by ionophore A23187, whereas the generation of superoxide anions was enhanced. Addition of partially purified PrKC to homogenates from ionophore A23187-stimulated PMN, reduced acetyltransferase activity by 63%, whereas only a 16% inhibition was observed on homogenates from resting PMN. These data indicate the modulation of acetyltransferase activity in human polymorphonuclear leukocytes by a phosphorylation-dephosphorylation mechanism linked to cyclic AMP-dependent protein kinase. Phospholipid sensitive, calcium-dependent protein kinase seems not to be involved in the mechanism of activation, but, most probably, in the generation of negative activation signals.

Evidence of a role for PAF-acether in the pathophysiology of the shock state.

The pathophysiology of the shock state includes a variety of hemodynamic changes such as systemic hypotension, pulmonary hypertension and increased vascular permeability leading to the extravasation of protein rich plasma. These changes can be initiated by different etiological factors, but many of them have been related to the stimulation of activation systems (complement, kinins, etc.) or to the generation of inflammatory mediators. The purpose of the present study has been to obtain evidence of the involvement of paf-acether in the pathogenesis of the shock state initiated in rat and mouse by Gram-negative bacteria and soluble aggregates of immunoglobulin G. The injection of 1-2 MDa aggregates of immunoglobulin G to normal Sprague-Dawley rats, induced a dose-dependent systemic hypotension which appeared about five minutes after completion of the intravenous challenge. Simultaneously, extravasation of protein-rich plasma occurred as judged from the finding of an increased clearance of 125I-BSA. In similar experiments in mice, a reduction of the vascular volume was observed using 51Cr-labelled homologous red blood cells. Under these conditions, a lipid compound analogous to paf-acether was obtained from the liver and the spleen of these animals. The generation of this compound preceded the development of blood volume depletion and could be suppressed by either quinacrine or depletion of mononuclear phagocytes by total irradiation with 700 rads. The previous treatment of the rats with the compound BN 52021 (a specific antagonist of the paf-acether receptor) at a dose of 5mg/kg, i.v., prevented the appearance of hypotension and extravasation in response to an i.v. challenge with soluble aggregates of immunoglobulin G. Interestingly, the reversal of hypotension was also observed when BN 52021 was infused after the immunoaggregates (5mg/kg). The possible involvement of paf-acether in the hemodynamic changes of Gram-negative sepsis was studied in rats which had received an intraperitoneal inoculation of E. coli. The animals inoculated with the doses of bacteria which produced mortality showed a time- and dose-dependent increase of vascular permeability as judged from the presence of abundant peritoneal exudate and the reduction of the circulating volume. Simultaneously, significant amounts of paf-acether could be obtained from the peritoneal exudate and from the spleen preceding to the development of the circulating volume depletion.(ABSTRACT TRUNCATED AT 400 WORDS)

Thrombin produces phosphorylation of cytosolic phospholipase A2 by a mitogen-activated protein kinase kinase-independent mechanism in the human astrocytoma cell line 1321N1.

The release of [3H]arachidonic acid was studied in the 1321N1 astrocytoma cell line upon stimulation with thrombin. The effect of thrombin was antagonized by hirudin only when both compounds were added simultaneously, which suggests activation of thrombin receptor. Evidence that the cytosolic phospholipase A2 (cPLA2) takes part in thrombin-induced arachidonate release was provided by the finding that thrombin induced retardation of the mobility of cPLA2 in SDS/polyacrylamide gels, which is a feature of the activation of cPLA2 by mitogen-activated protein (MAP) kinases. Thrombin induced activation of two members of the MAP kinase family whose consensus primary sequence appears in cPLA2, namely p42-MAP kinase and c-Jun kinase. However, the activation of c-Jun kinase preceded the phosphorylation of cPLA2 more clearly than the activation of p42-MAK kinase did. Both cPLA2 and c-Jun kinase activation were not affected by PD-98059, a specific inhibitor of MAP kinase kinases, which indeed completely blocked p42-MAP kinase shift. Heat shock, a well-known activator of c-Jun kinase, also phosphorylated cPLA2 but not p42-MAP kinase. These data indicate the existence in astrocytoma cells of a signalling pathway triggered by thrombin receptor stimulation that activates a kinase cascade acting on the Pro-Leu-Ser-Pro consensus primary sequence, activates cPLA2, and associates the release of arachidonate with nuclear signalling pathways.