Arachidonic acid pathway alterations in cerebrospinal fluid of dogs with naturally occurring spinal cord injury.

BACKGROUND: Canine intervertebral disc πherniation causes a naturally-occurring spinal cord injury (SCI) that bears critical similarities to human SCI with respect to both injury pathomechanisms and treatment. As such, it has tremendous potential to enhance our understanding of injury biology and the preclinical evaluation of novel therapies. Currently, there is limited understanding of the role of arachidonic acid metabolites in canine SCI. RESULTS: The CSF concentrations of PLA2 and PGE2 were higher in SCI dogs compared to control dogs (p = 0.0370 and 0.0273, respectively), but CSF LCT4 concentration in SCI dogs was significantly lower than that in control dogs (p < 0.0001). Prostaglandin E2 concentration in the CSF was significantly and positively associated with increased severity of SCI at the time of sampling (p = 0.041) and recovery 42 days post-injury (p = 0.006), as measured by ordinal behavioral scores. CONCLUSION: Arachidonic acid metabolism is altered in dogs with SCI, and these data suggest that these AA metabolites reflect injury severity and recovery, paralleling data from other model systems.

Prostaglandin E2 Mediates Cardiorespiratory Disturbances during Infection in Neonates.

OBJECTIVE: To determine whether infection, with associated eicosanoid release, is a main cause of respiratory disruption in neonates, by measuring levels of prostaglandin E2 (PGE2) and its metabolite (PGEM) in cerebrospinal fluid (CSF). STUDY DESIGN: Of 59 eligible infants, 25 preterm infants (mean gestational age, 28 ± 0.5 weeks) and 22 full-term infants (mean gestational age, 40 ± 0.5 weeks) from a level 3 neonatal intensive care unit and the general maternity neonatal ward were enrolled prospectively. Infants with a condition that can cause secondary apnea were excluded. Cardiorespiratory disturbances, such as apnea, bradycardia, and desaturation (ABD) events, were quantified. All infants were subjected to standard laboratory analysis of blood and CSF concentrations of biomarkers, including PGE2 and PGEM, within 24 hours of lumbar puncture, which were correlated with ABD events and culture-verified infections. RESULTS: PGEM levels were highest in infants with culture-verified sepsis and meningitis (P < .01). In infants without culture-verified bacterial infections, PGEM levels were higher in preterm infants compared with term infants (P < .05). The numbers of desaturation events and apnea events in neonates were positively associated with PGE2 levels in CSF (P < .05). CONCLUSION: PGE2 and PGEM are rapidly elevated in CSF during an infectious event and may explain cardiorespiratory disturbances, which are the major presenting symptoms of neonatal infections. PGE2 and PGEM are released during bacterial infections and could serve as biomarkers for sepsis and autonomic dysfunction in neonates.

Cancer-induced anorexia in tumor-bearing mice is dependent on cyclooxygenase-1.

It is well-established that prostaglandins (PGs) affect tumorigenesis, and evidence indicates that PGs also are important for the reduced food intake and body weight loss, the anorexia-cachexia syndrome, in malignant cancer. However, the identity of the PGs and the PG producing cyclooxygenase (COX) species responsible for cancer anorexia-cachexia is unknown. Here, we addressed this issue by transplanting mice with a tumor that elicits anorexia. Meal pattern analysis revealed that the anorexia in the tumor-bearing mice was due to decreased meal frequency. Treatment with a non-selective COX inhibitor attenuated the anorexia, and also tumor growth. When given at manifest anorexia, non-selective COX-inhibitors restored appetite and prevented body weight loss without affecting tumor size. Despite COX-2 induction in the cerebral blood vessels of tumor-bearing mice, a selective COX-2 inhibitor had no effect on the anorexia, whereas selective COX-1 inhibition delayed its onset. Tumor growth was associated with robust increase of PGE(2) levels in plasma - a response blocked both by non-selective COX-inhibition and by selective COX-1 inhibition, but not by COX-2 inhibition. However, there was no increase in PGE(2)-levels in the cerebrospinal fluid. Neutralization of plasma PGE(2) with specific antibodies did not ameliorate the anorexia, and genetic deletion of microsomal PGE synthase-1 (mPGES-1) affected neither anorexia nor tumor growth. Furthermore, tumor-bearing mice lacking EP(4) receptors selectively in the nervous system developed anorexia. These observations suggest that COX-enzymes, most likely COX-1, are involved in cancer-elicited anorexia and weight loss, but that these phenomena occur independently of host mPGES-1, PGE(2) and neuronal EP(4) signaling.

PGE-metabolite levels in CSF correlate to HIE score and outcome after perinatal asphyxia.

AIM: Acute anoxic exposure rapidly increases prostaglandin E2 (PGE2 ) production and release in neonatal mice brains. We hypothesize that PGE2 is released in human cerebrospinal fluid (CSF) during perinatal asphyxia and that it might be used as a biomarker for perinatal asphyxia. METHODS: In full-term infants with lumbar puncture performed within 72 h of birth (n = 35), CSF was analysed for prostaglandin E2 metabolite (PGEM) using an enzyme immunoassay. Term infants with suspected but unverified infections were used as controls (n = 11). Hypoxic-ischaemic encephalopathy (HIE) was classified as mild, moderate or severe (HIE I-III). Neurological assessment of surviving patients was performed at 18 months of age. RESULTS: Prostaglandin E2 metabolite levels correlated to a low Apgar score at 5 min (p < 0.01) and 10 min (p < 0.01), a low pH (p < 0.001) and HIE score (p < 0.05). The HIE-III cases (n = 7) had significantly higher PGEM levels compared with both controls and the HIE-I group (n = 8). Irrespective of HIE grade, patients with adverse or fatal outcome had higher PGEM values compared with controls and asphyxiated infants with normal outcome (p < 0.05). CONCLUSIONS: PGE2 is released during anoxic events in newborn infants, and PGEM may be useful as a biomarker for estimating degree of insult and predicting long-term outcome after perinatal asphyxia.

Febrile response induced by cecal ligation and puncture (CLP) in rats: involvement of prostaglandin E2 and cytokines.

The purpose of the present study was to better understand the events involved in the febrile response induced by cecal ligation and puncture (CLP), a complex infectious process. To this end, we conducted in vivo experiments in rats examining (1) fever development, (2) bacterial number in the infection focus and in blood, (3) peripheral and hypothalamic synthesis of cytokines, (4) hypothalamic and cerebrospinal fluid (CSF) synthesis of prostaglandin E(2) (PGE(2)), (5) the effect of anti-IL-6 antibody on fever, and (6) the effect of celecoxib on fever and hypothalamic synthesis of PGE(2) after CLP induction. We found that CLP promotes fever and animal death depending on the number of punctures. The peak of CLP-induced fever overlapped with the maximal increase in the number of bacteria in the infectious focus and blood, which occurred at 6 and 12 h. The peak of the febrile response also coincided with increased amounts of interleukin (IL)-1ß, IL-6 and IL-10 in the peritoneal exudate and serum; IL-6 in the hypothalamus and PGE(2) in the CSF and predominantly in the hypothalamus. Moreover, intracerebroventricularly injected anti-IL-6 antibody reduced the febrile response while celecoxib reduced the fever and PGE(2) amount in the hypothalamus induced by CLP. Tumor necrosis factor (TNF)-α peaked at 3 h at all sites studied. Conversely, IL-10 concentration decreased in the hypothalamus. These findings show that the peak of CLP-induced fever is accompanied by an increase of bacteria in peritoneal fluid (local infection) and blood; local synthesis of pyrogenic (IL-1ß, IL-6) and antipyretic (IL-10) cytokines and central production of IL-6 and PGE(2), suggesting that these last are the central mediators of this response.

Comparison of a bupivacaine peripheral nerve block and systemic ketoprofen on peripheral inflammation and hyperalgesia in rats.

BACKGROUND AND OBJECTIVE: Local anaesthetics via a nerve block can attenuate inflammation. However, their effects have never been compared with the anti-inflammatory effects of systemic NSAIDs. The aim of this study was to compare the effects of bupivacaine via sciatic block with a systemic NSAID on oedema and hyperalgesia and on indices of systemic inflammation as measured by cytokines and prostaglandin E2 production in a model of peripheral inflammation in rats. METHODS: Rats (n=56) randomly received three injections: a left subcutaneous hind paw injection (carrageenan or physiological saline); a left sciatic block (bupivacaine or physiological saline); and a systemic injection (ketoprofen or physiological saline). Six hours later, local oedema, thermal and mechanical hyperalgesia as well as cerebrospinal fluid prostaglandin E2 concentration and tumour necrosis factor-alpha and interleukin 1beta-stimulated production in whole blood cultures were measured. RESULTS: A sciatic block with bupivacaine as well as a systemic injection of NSAID significantly decreased the oedema and the thermal and mechanical hyperalgesia induced by carrageenan. Oedema was decreased by approximately 12%, and thermal and mechanical thresholds were increased by three-fold to fourfold and 1.5-2-fold, respectively. They both inhibited the increased production of prostaglandin E2 in cerebrospinal fluid and tumour necrosis factor-alpha and interleukin 1beta in stimulated whole blood induced by carrageenan. There was no further benefit of the combination of a sciatic block and systemic NSAID. CONCLUSION: In the current study, a bupivacaine block alone achieved the same anti-inflammatory effect as systemic NSAID or as when the same block is combined with a NSAID.

Elevated cerebrospinal fluid levels of prostaglandin E2 and 15-(S)-hydroxyeicosatetraenoic acid in multiple sclerosis.

OBJECTIVE: To test the hypothesis that the arachodinic acid metabolites prostaglandin E2 (PGE2) and 15-(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) in cerebrospinal fluid (CSF) are elevated and reflect neuroinflammation and degenerative changes in multiple sclerosis (MS). PATIENTS AND METHODS: We measured PGE2 and 15(S)-HETE concentrations, as well as markers of axonal and astroglial injury in CSF from 46 MS patients, 46 healthy siblings and 50 controls. RESULTS: We found elevated levels of both PGE2 and 15(S)-HETE in MS compared with the control and sibling groups. Siblings had lower PGE2 levels and higher 15(S)-HETE levels than controls. There were no correlations between either PGE2 or 15(S)-HETE and clinical scores of MS severity or biochemical markers of axonal or astroglial injury. CONCLUSION: These data suggest no direct involvement of PGE2 and 15(S)-HETE in the MS disease process. Rather, the elevated levels reflect a general up-regulation of arachidonic acid metabolism and neuroinflammation.

Central gene transfer of interleukin-10 reduces hypothalamic inflammation and evidence of heart failure in rats after myocardial infarction.

The expression of proinflammatory cytokines increases in hypothalamus of rats with myocardial infarction (MI) and heart failure. We used central gene transfer of human interleukin (IL)-10, a potent antiinflammatory cytokine, to counter the effects of brain proinflammatory cytokines and examine their functional significance. Sprague-Dawley rats underwent coronary ligation to induce MI or sham surgery (SHAM). One week later, adenoviral vectors encoding human IL-10 (AdIL-10) or beta-galactosidase (betaGal) were injected (30 microL over 30 minutes) into lateral ventricle. One week after injection, there was abundant expression of human IL-10 in the brain of MI+AdIL-10 and SHAM+AdIL-10 rats. Compared with SHAM+betaGal, MI+betaGal had increased (P<0.05) IL-1beta and cyclooxygenase-2 mRNA and protein and nuclear factor kappaB activity in the hypothalamus, cyclooxygenase-2 fluorescence in perivascular cells of the paraventricular nucleus of hypothalamus, prostaglandin E(2) in cerebrospinal fluid, and Fra-like activity (indicating neuronal excitation) in paraventricular nucleus. Plasma norepinephrine levels, lung/body weight, right ventricle/body weight, and left ventricular end-diastolic pressure were increased and maximal left ventricular dP/dt was decreased. All of these findings were ameliorated in MI rats treated with AdIL-10. Hypothalamic tumor necrosis factor-alpha and circulating tumor necrosis factor-alpha and IL-1beta levels, also increased in MI+betaGal, were not affected by AdIL-10 treatment. Rat native IL-10 was not affected by MI or AdIL-10. AdIL-10 had no effects on SHAM rats. The results demonstrate that cardiovascular and autonomic mechanisms leading to heart failure after MI can be modulated by manipulating the balance between proinflammatory and antiinflammatory cytokines in the brain.

CSF profiles of angiogenic and inflammatory factors depend on the respiratory status of ALS patients.

Our objective was to assess the regulation of the hypoxia response of angiogenic and inflammatory factors from 76 cerebrospinal fluids (CSF) of sporadic amyotrophic lateral sclerosis (ALS) patients with different respiratory status. We first analysed the hypoxia response capacity by measuring CSF levels of angiogenin (ANG), VEGF, angiopoietin-2 (ANG-2) and PGE-2 in 40 ALS patients according to their hypoxaemia level and compared it with 40 neurological controls. We then compared the ANG, VEGF, EPO and ANG-2 CSF levels of 36 other ALS patients, divided into three groups with either 1) normoxaemia, 2) intermittent desaturation in the absence of hypoxaemia, or 3) chronic hypoxaemia with or without desaturation. We demonstrated a lack of up-regulation of both ANG and VEGF during hypoxaemia in ALS, compared with hypoxaemic controls. In contrast, PGE-2 and ANG-2 levels were increased in both hypoxaemic ALS patients and controls. ANG and VEGF levels did not increase in patients with long disease durations and with intermittent or chronic hypoxaemia. ANG-2 and EPO levels were up-regulated early in intermittent hypoxaemia and late in chronic hypoxaemia, respectively. Our results suggest alteration of the HIF-1alpha-mediated response to hypoxia during sporadic ALS, whereas the NFK-B pathway seems early activated.

Comparison of the effects of intrathecal administration of levobupivacaine and lidocaine on the prostaglandin E2 and glutamate increases in cerebrospinal fluid: a microdialysis study in freely moving rats.

BACKGROUND: Bupivacaine has a lower incidence of transient neurological symptoms than lidocaine after intrathecal (i.t.) injection. The increased toxic potential of lidocaine does not support its use in the clinical setting and could be related to augmented levels of spinal prostaglandin E(2) (PGE(2)). We tested whether levobupivacaine leads to lower PGE(2) levels than lidocaine. Moreover, we compared the release of PGE(2) and glutamate after i.t. injections of levobupivacaine or lidocaine. METHODS: Rats were anaesthetized for implantation of an i.t. dialysis catheter. This allowed sampling dialysates of cerebrospinal fluid (CSF) for measuring PGE(2) and glutamate levels. The microdialysis setting included baseline sampling and was followed by an i.t. injection of levobupivacaine 250 microg, 100 microg, or saline. PGE(2) and glutamate levels in CSF were analysed for 4 h. In addition, the residual effect of a second i.t. injection on, respectively, of PGE(2) and glutamate changes was compared after injection of either 250 or 100 microg levobupivacaine, 1000 or 400 microg lidocaine, or saline. RESULTS: Prolonged spinal PGE(2) increases lasting 50-120 min were observed after levobupivacaine injection. Higher PGE(2) concentrations were observed after the second lidocaine 1000 microg injection. Glutamate release after the second injection did not vary between the local anaesthetic groups. CONCLUSIONS: Spinal PGE(2) levels are similarly increased after i.t. levobupivacaine injection of 250 and 100 microg. A higher PGE(2) response was observed after a second i.t. injection in the animals receiving 1000 microg lidocaine than those receiving 400 mg lidocaine or either dose of levobupivacaine.

The importance of brain PGE2 inhibition versus paw PGE2 inhibition as a mechanism for the separation of analgesic and antipyretic effects of lornoxicam in rats with paw inflammation.

OBJECTIVES: Lornoxicam is a non-selective cyclooxygenase inhibitor that exhibits strong analgesic and anti-inflammatory effects but a weak antipyretic effect in rat models. Our aim was to investigate the mechanism of separation of potencies or analgesic and antipyretic effects of lornoxicam in relation to its effect on prostaglandin E2 (PGE2) production in the inflammatory paw and the brain. METHODS: A model of acute or chronic paw inflammation was induced by Freund's complete adjuvant injection into the rat paw. Lornoxicam (0.01-1 mg/kg), celecoxib (0.3-30 mg/kg) or loxoprofen (0.3-30 mg/kg) was administered orally to the rats and the analgesic and antipyretic effects were compared. The paw hyperalgesia was assessed using the Randall-Selitto test or the flexion test. Dorsal subcutaneous body temperature was measured as indicator of pyresis. After the measurement of activities, the rats were sacrificed and the PGE2 content in the paw exudate, cerebrospinal fluid or brain hypothalamus was measured by enzyme-immunoassay. KEY FINDINGS: In a chronic model of arthritis, lornoxicam, celecoxib and loxoprofen reduced hyperalgesia with an effective dose that provides 50% inhibition (ED50) of 0.083, 3.9 and 4.3 mg/kg respectively, whereas the effective dose of these drugs in pyresis was 0.58, 0.31 and 0.71 mg/kg respectively. These drugs significantly reduced the PGE2 level in paw exudate and the cerebrospinal fluid. In acute oedematous rats, lornoxicam 0.16 mg/kg, celecoxib 4 mg/kg and loxoprofen 2.4 mg/kg significantly reduced hyperalgesia to a similar extent. On the other hand, lornoxicam did not affect the elevated body temperature, whereas celecoxib and loxoprofen significantly reduced the pyrexia to almost the normal level. These drugs significantly reduced the PGE2 level in inflamed paw exudate lo almost the normal level. On the other hand, lornoxicam did not change PGE2 level in the brain hypothalamus, whereas celecoxib and loxoprofen strongly decreased it. CONCLUSIONS: Lornoxicam exhibits strong analgesic but weak antipyretic effects in rats with paw inflammation. Such a separation of effects is related to its efficacy in the reduction of PGE2 levels in the paw and brain hypothalamus.

Novel Biochemical Insights in the Cerebrospinal Fluid of Patients with Neurosyphilis Based on a Metabonomics Study.

Neurosyphilis is a chronic central nervous system infectious disease caused by Treponema pallidum. Our aim was to study the metabolic profiling in the cerebrospinal fluid of neurosyphilis patients and identify specific potential biomarkers. Fifteen cerebrospinal fluid samples from neurosyphilis patients and 14 non-neurosyphilis samples were analyzed by liquid chromatography-mass spectrometer (LC-MS). The LC-MS data were preprocessed by supervised pattern recognition to obtain diagnostic models. Both orthogonal projections to a latent structures discriminant analysis (OPLS-DA) and a t test were used to obtain specific metabolites for neurosyphilis. LC-MS data showed that the metabolites in cerebrospinal fluid (CSF) from neurosyphilis are different from the non-neurosyphilis group. The OPLS-DA model parameters R2Y and Q2Y are both more than 0.7 and indicated a satisfactory diagnostic performance. Bilirubin, L-histidine, prostaglandin E2, alpha-kamlolenic acid, and butyryl-L-carnitine and palmitoyl-L-carnitine were identified as novel potential biomarkers for neurosyphilis. The metabolic study of CSF may provide a new way to explore the pathogenesis of neurosyphilis.

Cytokine-induced neutrophil chemoattractant (CINC)-1 induces fever by a prostaglandin-dependent mechanism in rats.

Cytokine-induced neutrophil chemoattractant-1 (CINC-1), a member of the ELR+CXC subfamily [ELR motif (glutamic acid-leucine-arginine) adjacent to the cysteine-X-cysteine (CXC) motif located at the N-terminus of the protein], is an acute-phase protein and its synthesis is induced by endogenous and exogenous pyrogens. However, there are no studies on the pyrogenic property of CINC-1. Therefore, the present study evaluates whether centrally administered CINC-1 promotes an integrated febrile response along with an increase in the prostaglandin (PG)E2 content of the cerebrospinal fluid (CSF) of rats. The effects of antipyretic drugs on fever and on the PGE2 content of the CSF as well as the effectiveness of a neutralizing anti-CINC-1 antibody on the fever induced by CINC-1 have also been investigated. Intracerebroventricular (i.c.v.) injection of CINC-1 induced a dose-dependent bell-shaped rise on body temperature and increased PGE2 concentration in the CSF of conscious rats. Injected into the preoptic area of the anterior hypothalamus (AH/POA) (i.h.), CINC-1 also induced a dose-dependent bell-shaped increase in body temperature along with a decrease on tail skin temperature. Indomethacin (INDO, 2 mg kg(-1), i.p.) and ibuprofen (IBU, 10 mg kg(-1), i.p.) markedly reduced the fever evoked by i.c.v. injection of CINC-1 (25 ng/site). Orally given celecoxib (5 mg kg(-1), 30 min. before) abolished the fever induced by CINC-1 i.c.v. or i.h. (50 pg) injection. The antipyretic drugs also blocked the PGE(2) increase after CINC-1 i.c.v. injection. Co-injected anti-CINC antibody (10 ng/site) strongly reduced the febrile response induced by CINC-1 (50 pg/site) injected intrahypothalamically. This is the first time that centrally injected CINC-1 has been reported to act directly on the pyrogen-sensitive neurons of AH/POA, promoting a thermoregulatory response that seems to depend on other endogenous pyrogens synthesis and, as seen here, on PGE2.

Intrathecal lidocaine elevates prostaglandin E2 levels in cerebrospinal fluid: a microdialysis study in freely moving rats.

BACKGROUND: In this study, we have investigated whether intrathecal (i.t.) lidocaine administration is accompanied with changes of cerebrospinal fluid (CSF) prostaglandin E(2) (PGE(2)) levels. METHODS: Rats were anaesthetized for i.t. implantation of a triple-lumen spinal loop dialysis catheter. CSF changes in PGE(2) after i.t. injection of saline, 400, or 1000 microg of lidocaine were measured. The impact of i.t. pretreatment with 5 microg MK801 (N-methyl-D-aspartate glutamate antagonist) or 10 microg SC76309A (COX-2 inhibitor) was also investigated. CSF dialysates for measurement of PGE(2) were collected for 4 h. During the whole procedure, motor and sensory blocks were evaluated. A separate group receiving i.t. lidocaine 400 microg (without dialysate sampling) was assessed for mechanical (Von Frey) and radiant heat pain. RESULTS: PGE(2) levels increased to 400% of baseline and remained elevated for 90-120 min after i.t. lidocaine at both doses. Pretreatment with SC76309A and MK801 attenuated this increase. A 40 min period of enhanced pain response was observed after Von Frey filament stimulation during and after sensory and motor block recovery. CONCLUSIONS: I.T. lidocaine (400 or 1000 microg) increases PGE(2) levels in the CSF for 90-120 min along with a transient period of mechanical hyperalgesia after sensory and motor block recovery.

Microsomal prostaglandin E synthase-1 is the central switch during immune-induced pyresis.

We studied the febrile response in mice deficient in microsomal prostaglandin E synthase-1 (mPGES-1), an inducible terminal isomerase expressed in cytokine-sensitive brain endothelial cells. These animals showed no fever and no central prostaglandin (PG) E2 synthesis after peripheral injection of bacterial-wall lipopolysaccharide, but their pyretic capacity in response to centrally administered PGE2 was intact. Our findings identify mPGES-1 as the central switch during immune-induced pyresis and as a target for the treatment of fever and other PGE2-dependent acute phase reactions elicited by the brain.

Vasodilatory prostaglandins in perinatal hypoxic brain damage.

Prostaglandin (PGE2 and PGI2) synthesis was determined in the cerebrospinal fluid (CSF) and serum of 19 hypoxic neonates at the age of 5-96 hours by using Enzyme Linked Immunosorbent Assay (ELISA) method. Control group consisted of 8 children of the same age whose samples were taken due to initial suspicion of neonatal meningitis. The prostaglandin concentrations in CSF were correlated with initial hypoxic-ischemic encephalopathy (HIE) stage and neurological findings of patients at the age of 12 months. The values of PGE2 and PGI2 in the CSF of children with perinatal hypoxia (PNH) were significantly higher than in the children from the control group. The values of PGI2 in serum were significantly higher than in "CSF" of patients with PNH. Although average values of PGE2 and PGI2 in the liquor were higher in children with advanced stage of HIE, the differences between different stages were not statistically significant. We did not find any significant correlation between average concentrations ofprostaglandins and neurological findings of the 12-month-old children.

Influence of plasma protein on the potencies of inhibitors of cyclooxygenase-1 and -2.

It is widely believed that the potencies of nonsteroid anti-inflammatory drugs (NSAIDs) as inhibitors of cyclooxygenase (COX) are influenced by protein binding in the extracellular fluid, since NSAIDs are bound to circulating albumin by well over 95%. This is an important point because the protein concentrations in synovial fluid and the central nervous system, which are sites of NSAID action, are markedly different from those in plasma. Here we have used a modified whole-blood assay to compare the potencies of aspirin, celecoxib, diclofenac, indomethacin, lumiracoxib, meloxicam, naproxen, rofecoxib, sodium salicylate, and SC560 as inhibitors of COX-1 and COX-2 in the presence of differing concentrations of protein. The potencies of diclofenac, naproxen, rofecoxib, and salicylate, but not aspirin, celecoxib, indomethacin, lumiracoxib, meloxicam, or SC560, against COX-1 (human platelets) increased as protein concentrations were reduced. Varying protein concentrations did not affect the potencies of any of the drugs against COX-2, with the exception of sodium salicylate (A549 cells). Clearly, our findings show that the selectivity of inhibitors for COX-1 and COX-2, which are taken to be linked to their efficacy and side effects, may change in different extracellular fluid conditions. In particular, selectivity in one body compartment does not demonstrate selectivity in another. Thus, whole-body safety or toxicity cannot be linked to one definitive measure of COX selectivity.

CCR1 and CCR5 chemokine receptors are involved in fever induced by LPS (E. coli) and RANTES in rats.

This study, besides examining the involvement of CCR1 and CCR5 receptors in the LPS-induced fever (lipopolysaccharide, Escherichia coli) in male Wistar rats, evaluated if RANTES (regulated on activation, normal T cells expressed and secreted) injected into the preoptic area of the anterior hypothalamus (AH/POA) would promote an integrated febrile response via these receptors. Moreover, the effects of selective and non-selective cyclooxygenase blockers on both fever and the level of prostaglandin (PG)E(2) in the cerebrospinal fluid (CSF) after injection of RANTES into the AH/POA were also investigated. Met-RANTES, CCR1 and CCR5 receptor antagonist, reduced LPS-evoked fever dose dependently. RANTES microinjected into the AH/POA increased the rectal temperature of rats dose dependently and caused a significant decrease in the tail skin temperature and an increase (at 2.5 and 5 h) of the levels of PGE(2) in the CSF. Met-RANTES prevented the fever induced by RANTES. Ibuprofen abolished the fever caused by RANTES between 60 min and 2.5 h, and it reduced the temperature until the end of observation period. Celecoxib blocked the RANTES-induced fever, while indomethacin reduced it in the last 60 min of the experimental period. At 2.5 and 5 h all antipyretics brought the CSF PGE(2) level near to the control. These results indicate that CCR1 and CCR5 receptors are involved in the fever induced by systemic LPS and intrahypothalamic RANTES. RANTES promotes an integrated febrile response accompanied by an increase of CSF PGE(2). The inhibitory effects of celecoxib and ibuprofen suggest that PGE(2) was generated via COX-2. As indomethacin dissociates fever and the decrease of PGE(2) level during the RANTES-induced fever, an alternative COX-2-independent pathway or other mechanisms of action of celecoxib and ibuprofen might be considered.

Increased tumor necrosis factor-alpha and prostaglandin E2 concentrations in the cerebrospinal fluid of rats with inflammatory hyperalgesia: the effects of analgesic drugs.

BACKGROUND: We examined the changes in cerebrospinal fluid (CSF) concentrations of prostaglandin E2 (PGE2) and tumor necrosis factor-alpha (TNF-alpha) after intraplantar administration of complete Freund's adjuvant (CFA) in rats. In addition, we investigated whether different analgesic drugs orally administered at antihyperalgesic doses were able to prevent the changes in PGE2 and TNF-alpha spinal levels associated with hindpaw inflammation. METHODS: The Randall-Selitto paw-withdrawal test was used to measure inflammatory hyperalgesia. Tramadol (7.5 mg/kg), paracetamol (65 mg/kg), tramadol plus paracetamol and nimesulide (5 mg/kg) were administered orally twice a day, starting from the first day after the CFA injection. PGE2 in the CSF was measured by enzyme immunoassay, and TNF-alpha by ELISA. Behavioral and biochemical parameters were measured on Day 7 after intraplantar injection of CFA or saline. RESULTS: Withdrawal thresholds to mechanical stimuli decreased markedly in the CFA-treated paw. In these animals the quantification of proinflammatory mediators in the CSF revealed a significant increase in both PGE2 and TNF-alpha concentrations. All the pharmacological treatments prevented the development of the hyperalgesia as well as the PGE2 increase in the CSF. Conversely, a prevention of the increase in TNF-alpha levels was observed only in rats treated with nimesulide or tramadol and paracetamol in combination. CONCLUSIONS: Our results demonstrate that peripheral inflammatory hyperalgesia is associated with significant changes of proinflammatory mediators in the CSF. It is important to note, however, that spinal PGE2 and TNF-alpha proved to be differently affected by pharmacological treatments able to fully abolish the hyperalgesia.

Endotoxin fever in granulocytopenic rats: evidence that brain cyclooxygenase-2 is more important than circulating prostaglandin E(2).

PGE(2) is a recognized mediator of many fevers, and cyclooxygenase (COX) is the major therapeutic target for antipyretic therapy. The source, as well as the site of action of PGE(2), as an endogenous pyrogen, is widely accepted as being central, but PGE(2) in the circulation, possibly from leukocytes, may also contribute to the development of fever. However, bacterial infections are important causes of high fever in patients receiving myelosuppressive chemotherapy, and such fevers persist despite the use of COX inhibitors. In the study reported here, the febrile response to bacterial LPS was measured in rats made leukopenic by cyclophosphamide. A striking increase in LPS fever occurred in these granulocytopenic rats when compared with febrile responses in normal animals. Unlike LPS fever in normal rats, fever in granulocytopenic rats was neither accompanied by an increase in blood PGE(2) nor inhibited by ibuprofen. Both leukopenic and normal rats showed LPS-induced COX-2-immunoreactivity in cells associated with brain blood vessels. Furthermore, LPS induced an increase of PGE(2) in cerebrospinal fluid. Induction of COX-2-expression and PGE(2) production was inhibited by ibuprofen in normal but not in leukopenic rats. Although the results presented are, in part, confirmatory, they add new information to this field and open a number of important questions as yet unresolved. Overall, the present results indicate that, in contrast to immunocompetent rats, leukocytes and/or other mechanisms other than PGE(2) are implicated in the mechanisms restricting and reducing the enhanced febrile response to endotoxin in immunosuppressed hosts.