Pharmacodynamic of cyclooxygenase inhibitors in humans

We provide comprehensive knowledge on the differential regulation of expression and catalysis of cyclooxygenase (COX)-1 and COX-2 in health and disease which represents an essential requirement to read out the clinical consequences of selective and nonselective inhibition of COX-isozymes in humans. Furthermore, we describe the pharmacodynamic and pharmacokinetic characteristics of major traditional nonsteroidal anti-inflammatory drugs (tNSAIDs) and coxibs (selective COX-2 inhibitors) which play a prime role in their efficacy and toxicity. Important information derived from our pharmacological studies has clarified that nonselective COX inhibitors should be considered the tNSAIDs with a balanced inhibitory effect on both COX-isozymes (exemplified by ibuprofen and naproxen). In contrast, the tNSAIDs meloxicam, nimesulide and diclofenac (which are from 18- to 29-fold more potent towards COX-2 in vitro) and coxibs (i.e. celecoxib, valdecoxib, rofecoxib, etoricoxib and lumiracoxib, which are from 30- to 433-fold more potent towards COX-2 in vitro) should be comprised into the cluster of COX-2 inhibitors. However, the dose and frequency of administration together with individual responses will drive the degree of COX-2 inhibition and selectivity achieved in vivo. The results of clinical pharmacology of COX inhibitors support the concept that the inhibition of platelet COX-1 may translate into an increased incidence of serious upper gastrointestinal bleeding but this effect on platelet COX-1 may mitigate the cardiovascular hazard associated with the profound inhibition of COX-2-dependent prostacyclin (PGI2).     

Mucosal damage induced by preferential COX-1 and COX-2 inhibitors: role of prostaglandins and inflammatory response

Nonsteroidal anti-inflammatory drugs (NSAID) are well known to induce gastric mucosal damage including bleeding, ulceration and perforation in humans and animals too. These effects are related with the inhibition of the enzyme cyclooxygenase, which is the main established mechanism of action for these drugs. Fasted rats were given piroxicam, preferential COX-1 inhibitor (10-20 mg/kg) or meloxicam, preferential COX-2 inhibitor (7.5-15 mg/kg) orally. Six or nine hours (h) later, respectively, the stomach was excised, the severity of the damage assessed and myeloperoxidase (MPO) activity measured, as well as prostaglandin PGE(2) content. Furthermore, in order to assess the effects of these oxicams over previously damaged gastric mucosa, 1 ml of 0.6 N HCl was administered p.o. followed, 1 h after, of the correspondent dose of each NSAID, and the same parameters were determined. Oral administration of both drugs dose-dependently caused acute gastric haemorrhage erosions. Myeloperoxidase activity was significantly increased by piroxicam administration. In addition, PGE(2) content was significantly reduced. The association between the administration of the acid and NSAID caused a worsening of the damage and, while myeloperoxidase activity did not modify by both piroxicam and meloxicam, PGE(2) levels were reduced. These results suggest that the PG derived from both COX-1 and COX-2 pathway plays a beneficial role in the gastroprotection, and thus caution should be exercise in the clinical use of preferential COX-2 inhibitors.     

Effects of a local anaesthetic and NSAID in castration of piglets,on the acute pain responses,growth and mortality

The present study addresses the questions whether on-farm use of local anaesthesia with lidocaine leads to a reduction in pain responses during castration, and whether the non-steroidal anti-inflammatory drug meloxicam improves technical performance after castration of piglets. Five treatments were included in the study: (1) castration without anaesthesia or analgesia (CAST), (2) castration after local anaesthesia with lidocaine (LIDO), (3) castration after administration of meloxicam (MELO), (4) castration after lidocaine and meloxicam (L + M) and (5) sham castration (SHAM). To reduce litter influences, each treatment was present in each of the 32 litters (n = 32 per treatment). During castration, vocalizations were recorded continuously. Blood samples were collected 15 min before and 20 min after castration for determination of plasma levels of total cortisol, glucose, lactate and creatine kinase (CK). Mortality was registered and piglets were weighed several times to calculate growth. Several aspects of vocalizations during castration showed consistent and significantly different levels in CAST compared with LIDO, L + M and SHAM. CAST piglets squealed longer, louder and higher. Vocalizations of MELO piglets most resembled those of CAST. An increase in cortisol was seen in all treatments. However, in SHAM piglets this increase was significantly lower than in the other treatments. LIDO piglets showed a significantly smaller increase in plasma cortisol levels compared with CAST and MELO. L + M piglets differed significantly only from the SHAM group. Lactate levels differed significantly between LIDO and MELO, the level in LIDO being decreased after castration. In the other treatments an increase was measured. No treatment effects were found in plasma glucose and CK levels, nor in growth and mortality of the piglets. In conclusion, on the basis of vocalizations and plasma cortisol, local anaesthesia with lidocaine reduces pain responses in piglets during castration. A positive effect of meloxicam on technical performance was not found.     

Effects of meloxicam (Metacam®) on post-farrowing sow behaviour and piglet performance

Farrowing is an intrinsically risky process for both the sow and the piglets that can cause welfare and economic problems. The effects of the non-steroidal anti-inflammatory drug meloxicam on post-farrowing behaviour of sows, and the performance of piglets were investigated. A total of 48 sows were randomly allocated at the day of farrowing (day 0) into two homogeneous groups regarding parity, and treated with either meloxicam or saline solution as placebo. For each sow, number of position changes, total time lying and standing or sitting, feed intake and rectal temperature (RT) were recorded during 3 days after farrowing. Piglets were individually weighed at farrowing and at weaning. The number of position changes did not show significant differences between treatments (P = 0.79). Sows spent significantly less time lying during day +3 after farrowing in the meloxicam group than in the placebo group (P = 0.04). Feed intake and RT showed a parity effect (P < 0.001 in both cases); however, no treatment effect was observed (P = 0.67 and P = 0.47, respectively). Pre-weaning mortality rate in piglets was not affected by treatment. In litters from multiparous sows, piglets of low birth weight (defined as percentile 15: BW <1180 g) had an average daily gain significantly higher in the meloxicam group than in the placebo group (196.6 ± 7.2 v. 166.6 ± 9.1 g/day; P = 0.03). Although the administration of meloxicam 90 min after farrowing showed a positive effect on the total time lying of the sows, additional investigations are required to better qualify relevant indicators of pain following farrowing in sows and to specify the analgesic effects of meloxicam on piglet performance.     

Effects of Oxicam Inhibitors of Cyclooxygenase on Oxidative Stress Generation in Rat Gastric Mucosa. A Comparative Study

The aim of this study was to compare the effects of two nonsteroidal anti-inflammatory drugs (NSAID), members of the same family with a different cyclooxygenase (COX) inhibition selectivity, meloxicam, preferent COX-2 inhibitor, and piroxicam, preferent COX-1 inhibitor, on oxygen radical generation in rat gastric mucosa. Therefore, the activity of oxidative stress-related enzymes such as xanthine oxidase (XO), superoxide dismutase (SOD) and glutathione (GSH) homeostasis were studied in rats. Gastric prostaglandins (PG) were also assessed as a measure of COX-1 inhibition. Both oxicams produced a similar extent of the gastric mucosal damage and a significant decrease in PGE 2 synthesis, however only piroxicam induced an increase of both myeloperoxidase (MPO) activity and tumor necrosis factor (TNF)- &#102 content in the gastric mucosa, indicating that neutrophil-derived free radicals were involved in gastric injury. Furthermore, both compounds reduced SOD activity and increased XO activity in gastric mucosa. Our results also revealed modifications in GSH metabolism: although glutathione peroxidase (GSH-px) activity was unaffected by meloxicam or piroxicam administration, both glutathione reductase (GSSG-rd) activity and total GSH content were significantly decreased after dosing. These results suggest that under our experimental conditions, meloxicam, preferential COX-2 inhibitor causes rates of gastric lesion in rats comparable to those seen with the traditional NSAID piroxicam, preferential COX-1 inhibitor. In addition to suppression of systemic COX activity, oxygen radicals, probably derived via the XO, and neutrophils play an important role in the production of damage induced by both oxicams. Moreover, the decrease in SOD activity and changes in glutathione homeostasis in gastric mucosa may also contribute to pathogenesis of meloxicam- or piroxicam-induced gastropathy.     

Effects of oxicam inhibitors of cyclooxygenase on oxidative stress generation in rat gastric mucosa. A comparative study

The aim of this study was to compare the effects of two nonsteroidal anti-inflammatory drugs (NSAID), members of the same family with a different cyclooxygenase (COX) inhibition selectivity, meloxicam, preferent COX-2 inhibitor, and piroxicam, preferent COX-1 inhibitor, on oxygen radical generation in rat gastric mucosa. Therefore, the activity of oxidative stress-related enzymes such as xanthine oxidase (XO), superoxide dismutase (SOD) and glutathione (GSH) homeostasis were studied in rats. Gastric prostaglandins (PG) were also assessed as a measure of COX-1 inhibition. Both oxicams produced a similar extent of the gastric mucosal damage and a significant decrease in PGE2 synthesis, however only piroxicam induced an increase of both myeloperoxidase (MPO) activity and tumor necrosis factor (TNF)-alpha content in the gastric mucosa, indicating that neutrophil-derived free radicals were involved in gastric injury. Furthermore, both compounds reduced SOD activity and increased XO activity in gastric mucosa. Our results also revealed modifications in GSH metabolism: although glutathione peroxidase (GSH-px) activity was unaffected by meloxicam or piroxicam administration, both glutathione reductase (GSSG-rd) activity and total GSH content were significantly decreased after dosing. These results suggest that under our experimental conditions, meloxicam, preferential COX-2 inhibitor causes rates of gastric lesion in rats comparable to those seen with the traditional NSAID piroxicam, preferential COX-1 inhibitor. In addition to suppression of systemic COX activity, oxygen radicals, probably derived via the XO, and neutrophils play an important role in the production of damage induced by both oxicams. Moreover, the decrease in SOD activity and changes in glutathione homeostasis in gastric mucosa may also contribute to pathogenesis of meloxicam- or piroxicam-induced gastropathy.     

Oxicams Bind in a Novel Mode to the Cyclooxygenase Active Site via a Two-water-mediated H-bonding Network

Oxicams are widely used nonsteroidal anti-inflammatory drugs (NSAIDs), but little is known about the molecular basis of the interaction with their target enzymes, the cyclooxygenases (COX). Isoxicam is a nonselective inhibitor of COX-1 and COX-2 whereas meloxicam displays some selectivity for COX-2. Here we report crystal complexes of COX-2 with isoxicam and meloxicam at 2.0 and 2.45 angstroms, respectively, and a crystal complex of COX-1 with meloxicam at 2.4 angstroms. These structures reveal that the oxicams bind to the active site of COX-2 using a binding pose not seen with other NSAIDs through two highly coordinated water molecules. The 4-hydroxyl group on the thiazine ring partners with Ser-530 via hydrogen bonding, and the heteroatom of the carboxamide ring of the oxicam scaffold interacts with Tyr-385 and Ser-530 through a highly coordinated water molecule. The nitrogen atom of the thiazine and the oxygen atom of the carboxamide bind to Arg-120 and Tyr-355 via another highly ordered water molecule. The rotation of Leu-531 in the structure opens a novel binding pocket, which is not utilized for the binding of other NSAIDs. In addition, a detailed study of meloxicam·COX-2 interactions revealed that mutation of Val-434 to Ile significantly reduces inhibition by meloxicam due to subtle changes around Phe-518, giving rise to the preferential inhibition of COX-2 over COX-1.     

Synergistic anti-inflammatory interaction between meloxicam and aminoguanidine hydrochloride in carrageenan-induced acute inflammation in rats

Interaction studies with inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) inhibitor have been conducted to assess the nature of interaction and the possible therapeutic advantage. The interaction between meloxicam--a selective COX-2 inhibitor--and aminoguanidine hydrochloride--a selective iNOS inhibitor-- was examined in carrageenan-induced paw edema in rats. Appropriate statistical method was applied to detect the nature of anti-inflammatory interaction. Different doses of meloxicam (1, 3, 10 and 30 mg/kg) or aminoguanidine hydrochloride (10, 30, 100 and 300 mg/kg) were administered orally to adult male albino rats. Higher doses of meloxicam (3, 10 and 30 mg/kg) showed statistically significant anti-inflammatory effect. However, aminoguanidine hydrochloride did not show any anti-inflammatory activity. Combination of sub-threshold dose of meloxicam (1 mg/kg) with increasing doses of aminoguanidine hydrochloride (30, 100 and 300 mg/kg) resulted in synergistic anti-inflammatory effect. Combined therapy with sub-threshold dose of aminoguanidine hydrochloride (30 mg/kg) with increasing doses of meloxicam (1, 3, 10 and 30 mg/kg) also resulted in synergistic anti-inflammatory effect. The possible mechanism of interaction could be the stimulation of COX-2 activity by nitric oxide (NO) by combining with heme component. These results suggest that co-administration of meloxicam and aminoguanidine hydrochloride may be an alternative in clinical control of inflammation.     

Renal effect of meloxicam versus ketoprofen in anaesthetized pseudo-normovolaemic piglets

Due to renal COX-2 constitutive expression, meloxicam is presumably deleterious for kidney function in critical situations. The present study investigates the influence of intravenous meloxicam on renal parameters and compares it with a nonselective COX inhibitor, ketoprofen. Piglets (n = 6 in each group) were treated with ketoprofen (2 mg.kg(-1)), meloxicam (0.2 mg.kg(-1)), or saline at the beginning of anaesthesia. Under intravenous anaesthesia, pigs were instrumented for cardiovascular, respiratory, and renal function evaluation, including urinary flow (UF), glomerular filtration rate (GFR), and renal blood flow (RBF). After baseline data collection (U0), data collection consisted of six 20-minute periods (U1 to U6). In all groups, the time course of cardiovascular and respiratory parameters remained within normal ranges. A small decrease in cardiac output and an increase in mean systemic arterial blood pressure (p = 0.002) occurred in all groups. In the placebo group, a similar decrease was observed for RBF and cardiac output, with troughs of -10.1% +/- 6.8%, and -12.9% +/- 3.2%, respectively. GFR and UF, however, remained stable over time in this group. Ketoprofen significantly decreased UF (-29.3% +/- 5.5% max at U3), with similar decreases in GFR and RBF. Meloxicam induced a transient (at U2) and small decrease in UF with no difference, at any time point, with the placebo group. The renal effects of meloxicam appear minimal and transient in anaesthetized piglets. This study demonstrates the safety of meloxicam for preemptive surgical analgesia under conditions of normovolaemia. Fluid therapy appears recommended to prevent any renal dysfunction.     

Aspirin induces platelet receptor shedding via ADAM17 (TACE)

Aspirin is effective in the therapy of cardiovascular diseases, because it causes acetylation of cyclooxygenase 1 (COX-1) leading to irreversible inhibition of platelets. Additional mechanisms can be suspected, because patients treated with other platelet COX inhibitors such as indomethacin do not display an increased bleeding tendency as observed for aspirin-treated patients. Recently, aspirin and other anti-inflammatory drugs were shown to induce shedding of L-selectin in neutrophils in a metalloproteinase-dependent manner. Therefore, we investigated the effects of aspirin on the von Willebrand Factor receptor complex glycoprotein (GP) Ib-V-IX, whose lack or dysfunction causes bleeding in patients. As quantified by fluorescence-activated cell sorting analysis in whole blood, aspirin, but not its metabolite salicylic acid, induced dose-dependent shedding of human and murine GPIbalpha and GPV from the platelet surface, whereas other glycoproteins remained unaffected by this treatment. Biotinylated fragments of GPV were detected by immunoprecipitation in the supernatant of washed mouse platelets, and the expression level of GPIbalpha was decreased in these platelets as measured by Western blot analysis. Although shedding occurred normally in COX-1-deficient murine platelets, shedding was completely blocked by a broad-range metalloproteinase inhibitor and, more importantly, in mouse platelets expressing an inactive form of ADAM17. Shed fragments of GPIbalpha and GPV were elevated in the plasma of aspirin-injected mice compared with animals injected with control buffer. These data demonstrate that aspirin at high concentrations induces shedding of GPIbalpha and GPV by an ADAM17-dependent mechanism and that this process can occur in vivo.     

Anti-inflammatory activity of Camellia japonica oil

Camellia japonica oil (CJ oil) has been used traditionally in East Asia to nourish and soothe the skin as well as help restore the elasticity of skin. CJ oil has also been used on all types of bleeding instances. However, little is known about its anti-inflammatory effects. Therefore, the anti-inflammatory effects of CJ oil and its mechanisms of action were investigated. CJ oil inhibited LPS-induced production of NO, PGE(2), and TNF-α in RAW264.7 cells. In addition, expression of COX-2 and iNOS genes was reduced. To evaluate the mechanism of the anti-inflammatory activity of CJ oil, LPS-induced activation of AP-1 and NF-κB promoters was found to be significantly reduced by CJ oil. LPS-induced phosphorylation of IκBα, ERK, p38, and JNK was also attenuated. Our results indicate that CJ oil exerts anti-inflammatory effects by downregulating the expression of iNOS and COX-2 genes through inhibition of NF-κB and AP-1 signaling. [BMB reports 2012; 45(3): 177-182].     

Synthesis, biological evaluation and molecular docking studies of stellatin derivatives as cyclooxygenase (COX-1, COX-2) inhibitors and anti-inflammatory agents

Stellatin (4), isolated from Dysophylla stellata is a cyclooxygenase (COX) inhibitor. The present study reports the synthesis and biological evaluation of new stellatin derivatives for COX-1, COX-2 inhibitory and anti-inflammatory activities. Eight derivatives showed more pronounced COX-2 inhibition than stellatin and, 17 and 21 exhibited the highest COX-2 inhibition. They also exhibited the significant anti-inflammatory activity in TPA-induced mouse ear edema assay and their anti-inflammatory effects were more than that of stellatin and indomethacin at 0.5 mg/ear. The derivatives were further evaluated for antioxidant activity wherein 16 and 17 showed potent free radical scavenging activity against DPPH and ABTS radicals. Molecular docking study revealed the binding orientations of stellatin and its derivatives into the active sites of COX-1 and COX-2 and thereby helps to design the potent inhibitors.     

Impact of Transmammary-Delivered Meloxicam on Biomarkers of Pain and Distress in Piglets after Castration and Tail Docking

To investigate a novel route for providing analgesia to processed piglets via transmammary drug delivery, meloxicam was administered orally to sows after farrowing. The objectives of the study were to demonstrate meloxicam transfer from sows to piglets via milk and to describe the analgesic effects in piglets after processing through assessment of pain biomarkers and infrared thermography (IRT). Ten sows received either meloxicam (30 mg/kg) (n = 5) or whey protein (placebo) (n = 5) in their daily feedings, starting four days after farrowing and continuing for three consecutive days. During this period, blood and milk samples were collected at 12-hour intervals. On Day 5 after farrowing, three boars and three gilts from each litter were castrated or sham castrated, tail docked, and administered an iron injection. Piglet blood samples were collected immediately before processing and at predetermined times over an 84-hour period. IRT images were captured at each piglet blood collection point. Plasma was tested to confirm meloxicam concentrations using a validated high-performance liquid chromatography-mass spectrometry method. Meloxicam was detected in all piglets nursing on medicated sows at each time point, and the mean (± standard error of the mean) meloxicam concentration at castration was 568.9±105.8 ng/mL. Furthermore, ex-vivo prostaglandin E₂ (PGE₂) synthesis inhibition was greater in piglets from treated sows compared to controls (p = 0.0059). There was a time-by-treatment interaction for plasma cortisol (p = 0.0009), with meloxicam-treated piglets demonstrating lower cortisol concentrations than control piglets for 10 hours after castration. No differences in mean plasma substance P concentrations between treatment groups were observed (p = 0.67). Lower cranial skin temperatures on IRT were observed in placebo compared to meloxicam-treated piglets (p = 0.015). This study demonstrates the successful transfer of meloxicam from sows to piglets through milk and corresponding analgesia after processing, as evidenced by a decrease in cortisol and PGE₂ levels and maintenance of cranial skin temperature.     

Design, synthesis, and biological evaluation of N-acetyl-2-(or 3-)carboxymethylbenzenesulfonamides as cyclooxygenase isozyme inhibitors

A group of N-acetyl-2-(or 3-)carboxymethylbenzenesulfonamides, possessing either a F or a substituted-phenyl ring substituent (4-F, 2,4-F2, 4-SO2Me, 4-OCHMe2) attached to its C-4 or C-6 position, was prepared using a palladium-catalyzed Suzuki cross-coupling reaction for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. Although N-acetyl-3-carboxymethyl-6-fluorobenzenesulfonamide [14, COX-1 IC50 = 2.26 microM; COX-2 IC50 = 0.012 microM; COX-2 selectivity index (SI) = 188] and N-acetyl-3-carboxymethyl-6-(4-isopropoxyphenyl)benzenesulfonamide (20c, COX-1 IC50 >100 microM; COX-2 IC50 = 0.15 microM; COX-2 SI >667) exhibited potent in vitro COX-2 inhibitory activity and high COX-2 selectivity, both compounds were inactive anti-inflammatory agents in a carrageenan-induced rat paw edema assay. In contrast, the less potent and less selective COX-2 inhibitors N-acetyl-2-carboxymethyl-4-fluorobenzenesulfonamide (12, COX-1 IC50 = 4.25 microM; COX-2 IC50 = 0.978 microM; COX-2 SI = 4.3), N-acetyl-2-carboxymethyl-4-(2,4-difluorophenyl)benzenesulfonamide (17c, COX-1 IC50 = 1.02 microM; COX-2 IC50 = 1.00 microM; COX-2 SI = 1.02), and N-acetyl-3-carboxymethyl-6-(4-methanesulfonylphenyl)benzenesulfonamide (20e, COX-1 IC50 = 0.109 microM; COX-2 IC50 = 1.14 microM; COX-2 SI = 0.095) exhibited moderate anti-inflammatory activity where a 75 mg/kg oral dose reduced inflammation 26%, 14%, and 20%, respectively, at 3 h postdrug administration relative to the reference drug aspirin where a 50 mg/kg oral dose reduced inflammation by 25% at 3 h postdrug administration.     

Acute physiological responses to castration-related pain in piglets: the effect of two local anesthetics with or without meloxicam

Methods to reduce castration-related pain in piglets are still issues of concern and interest for authorities and producers. Our objectives were to estimate the effectiveness of two protocols of local anesthesia (lidocaine and the combination of lidocaine+bupivacaine) as well as the use of meloxicam as a postoperative analgesic in alleviating castration-related pain, measured by acute physiological responses. Eight groups (15 piglets/group) were included in the study: (1) castration without anesthesia or analgesia, without meloxicam (TRAD WITHOUT), (2) castration without anesthesia or analgesia, but with meloxicam (TRAD WITH), (3) handling without meloxicam (SHAM WITHOUT), (4) handling with meloxicam (SHAM WITH), (5) castration after local anesthesia with lidocaine but without meloxicam (LIDO WITHOUT), (6) castration after local anesthesia with lidocaine and meloxicam (LIDO WITH), (7) castration after local anesthesia with lidocaine+bupivacaine without meloxicam (LIDO+BUPI WITHOUT), (8) castration after local anesthesia with lidocaine+bupivacaine and meloxicam (LIDO+BUPI WITH). Acute physiological responses measured included skin surface temperature and serum glucose and cortisol concentrations. On days 4 and 11 post-castration BW was recorded and average daily gain was calculated over this period. Furthermore, piglet mortality was recorded over the 11-day post-castration period. Administration of local anesthetic or meloxicam did not prevent the decrease in skin surface temperature associated with castration. Lidocaine reduced the increase in glucose concentration associated with castration. For castrated pigs, the joint use of lidocaine and meloxicam caused a significant decrease in cortisol concentration; the combination of intratesticular lidocaine and bupivacaine did not seem to be more effective than lidocaine alone. No effect of treatments on mortality and growth were detected.     

Cyclooxygenase inhibitor blocks rebound response after NO inhalation in an endotoxin model

This study addressed the possible role of cyclooxygenase (COX) and its products in the rebound response to inhaled nitric oxide (INO). Anesthetized, mechanically ventilated piglets were exposed to endotoxin alone, endotoxin combined with INO, or endotoxin with INO plus the COX inhibitor diclofenac (3 mg/kg iv) (n = 8 piglets/group). A control group of healthy pigs (n = 6) was also studied. Measurements were made of blood gases, hemodynamic parameters, lung tissue COX expression, and plasma concentrations of thromboxane B(2) (TxB(2)), PGF(2alpha), and 6-keto-PGF(1alpha). Endotoxin increased lung inducible COX (COX-2) expression and circulating prostanoids concentrations. Inhalation of NO during endotoxemia increased the constitutive COX (COX-1) expression, and the circulating TxB(2) and PGF(2alpha) increased further after INO withdrawal. The combination of COX inhibitor with INO blocked all these changes and eliminated the rebound reaction to INO withdrawal, which otherwise was seen in endotoxemic piglets given INO only. We conclude that the rebound response to INO discontinuation is related to COX products.     

Role of nitric oxide and cyclooxygenase-2 in regulating the renal hemodynamic response to norepinephrine

We have reported that the renal hemodynamic effects of norepinephrine (NE) are modulated by cyclooxygenase-2 (COX-2)-derived metabolites. Our main objective was to examine whether there is an interaction between nitric oxide (NO) and COX-2 in modulating the renal hemodynamic effects of NE. NE was infused at three doses to anesthetized dogs pretreated with vehicle (n = 8), a selective COX-2 inhibitor (nimesulide) (n = 6), an NO synthesis inhibitor [NG-nitro-l-arginine methyl ester; l-NAME] (n = 8), or with nimesulide and l-NAME (n = 5). During NE infusion, PGE2 excretion increased (125%) in the control group and did not change in the l-NAME-treated dogs. The simultaneous inhibition of NO and COX-2 potentiated to a greater extent the NE-induced renal vasoconstriction than inhibition of either NO or COX-2. The NE-induced renal vasoconstriction during NO and COX-2 inhibition was reduced (P < 0.05) by infusing an AT1 receptor antagonist (n = 6). These results suggest that there is an interaction between NO and COX-2 in protecting the renal vasculature from the NE effects and that angiotensin II partly mediates the NE-induced renal vasoconstriction when NO synthesis and COX-2 activity are reduced.     

Experimental arthritis inhibits the insulin-like growth factor-I axis and induces muscle wasting through cyclooxygenase-2 activation

Chronic arthritis induces cachexia associated with an inhibition of the growth hormone (GH)-insulin-like growth factor-I (IGF-I) system and an activation of the E3 ubiquitin-ligating enzymes muscle atrophy F-box (MAFbx) and muscle Ring finger 1 (MuRF1) in the skeletal muscle. The aim of this work was to study the role of cyclooxygenase (COX)-2 in chronic arthritis-induced cachexia. Arthritis was induced in rats by Freund's adjuvant injection, and the effects of two COX inhibitors (indomethacin, a nonspecific inhibitor, and meloxicam, a selective COX-2 inhibitor on pituitary GH and on liver and serum IGF-I levels) were tested. Arthritis decreased body weight gain and GH and liver IGF-I gene expression. In the arthritic rats, both inhibitors, indomethacin and meloxicam, prevented the inhibitory effect of arthritis on body weight gain. Indomethacin and meloxicam administration to arthritic rats increased pituitary GH and liver IGF-I mRNA as well as serum levels of IGF-I. These data suggest that induction of COX-2 during chronic inflammation is involved in the inhibition of the GH-IGF-I axis and in the body weight loss. In the gastrocnemius muscle, arthritis increased the gene expression of tumor necrosis factor (TNF)-alpha, the E3 ubiquitin-ligating enzymes MAFbx and MuRF1, as well as of IGF-I and IGF-binding protein-5 (IGFBP-5). Inhibition of COX-2 by meloxicam administration increased gastrocnemius weight and decreased MAFbx, MuRF1, TNF-alpha, and IGFBP-5 gene expression. In summary, our data indicate that chronic arthritis-induced cachexia and muscle wasting are mediated by the COX-2 pathway resulting in a decreased GH-IGF-I secretion and increased expression of MAFbx and MuRF1 mRNA.     

Design, synthesis, and biological evaluation of substituted 2-alkylthio-1,5-diarylimidazoles as selective COX-2 inhibitors

A new type of 1-aryl-5-(4-methylsulfonylphenyl)imidazoles, possessing C-2 alkylthio (SMe or SEt) substituents, were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo anti-inflammatory activity. The compound, 1-(4-bromophenyl)-5-(4-methylsulfonylphenyl)-2-methylthioimidazole (11g), was the most potent and selective COX-2 inhibitor (COX-2 IC50=0.43 microM with no inhibition of COX-1 up to 25 microM) relative to the reference drug celecoxib (COX-2 IC50=0.21 microM with no inhibition of COX-1 up to 25 microM) and also showed very good anti-inflammatory activity compared to celecoxib in carrageenan-induced rat paw edema assay.     

Effects of the polymorphisms of Mx1, BAT2 and CXCL12 genes on immunological traits in pigs

It is necessary that genetic markers or biomarkers can be used to predict resistance towards a wide range of infectious diseases. In the present study, we estimated the potential markers and measured their relationship with heritabilities of a wide range of immune traits. Polymorphisms in exon 13 of Mx1, intron 25 of BAT2 and intron 3 of CXCL12 were identified by sequencing, and the genotypes were analyzed by PCR-RFLP in a resource population composed of 352 pure breed Landrace piglets at days 0, 17 and 32 after birth. Associations of single-nucleotide polymorphisms (SNPs) in these genes with a variety of immunological traits and antibody levels for pig reproduction and porcine respiratory syndrome virus (PRRSV), pseudorabies virus (PRV) and classical swine fever virus (CSFV) were performed. The performance of GG genotype of BAT2 on hemoglobin concentration (HBG) and hematocrit (HCT) of piglets at day 0 was significantly higher than that of the AA and AG individuals. For Mx1, compared with CT genotype, the pigs with TT or CC generated more PRRS antibody at day 0. The piglets with CT genotype had highly significant difference of PRV antibody from those with CC and TT genotypes at day 0. And the piglets with CC genotype had higher level red blood cell count (RBC), hemoglobin concentration (HBG) and hematocrit (HCT) than those with CT and TT genotypes at day 17. For the C7462G SNP in the intron 3 of CXCL12, the PRV antibody level of piglets with the CG genotype were higher than that of piglets with CC and GG genotypes at day 17, and the mean corpuscular volume (MCV) of GG piglets were larger than that of CC and CG individuals at day 0. At the locus 7331?bp in the intron 3 of CXCL12, there were significantly differences of mean corpuscular hemoglobin concentrations (MCHC) at day 0 and white blood cell count (WBC) at day 32, which showed the trend GG or AG>AA, AA>AG or GG, respectively. The pigs with AA or GG genotype had more platelet distribution width (PDW), mean platelet volume (MPV) and platelet-large cell ratio (PLR) at day 17 than those with AG. The results of this study indicated that polymorphisms in Mx1, BAT2 and CXCL12 genes were significantly associated with the immunological traits in Landrace piglets and had potential application value for marker-assisted selection of pig breeding with disease resistance.