Sirtinol attenuates hepatic injury and pro-inflammatory cytokine production following trauma-hemorrhage in male Sprague-Dawley rats.

BACKGROUND: Although studies have demonstrated that sirtinol administration following adverse circulatory conditions is known to be protective, the mechanism by which sirtinol produces the salutary effects remains unknown. We hypothesized that sirtinol administration in male rats following trauma-hemorrhage decreases cytokine production and protects against hepatic injury. METHODS: Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure 40 mmHg for 90 min, then resuscitation). A single dose of sirtinol (1 mg/kg of body weight) or vehicle was administered intravenously during resuscitation. Twenty-four hours thereafter, tissue myeloperoxidase (MPO) activity (a marker of neutrophil sequestration), cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-3, intercellular adhesion molecule (ICAM)-1, and interleukin (IL)-6 levels in the liver and plasma alanine aminotransferase (ALT) concentrations were measured (n=6 Sprague-Dawley rats/group). RESULTS: Trauma-hemorrhage increased hepatic MPO activity, CINC-1, CINC-3, ICAM-1, and IL-6 levels and plasma ALT concentrations. These parameters were significantly improved in the sirtinol-treated rats subjected to trauma-hemorrhage. CONCLUSION: The salutary effects of sirtinol administration on attenuation of hepatic injury following trauma-hemorrhage are, at least in part, related to reduction of pro-inflammatory mediators.

Mouse spinal cord compression injury is reduced by either activation of the adenosine A2A receptor on bone marrow-derived cells or deletion of the A2A receptor on non-bone marrow-derived cells.

Activation of the adenosine A(2A) receptor (A(2A)R) at the time of reperfusion has been shown to reduce ischemia-reperfusion injury in peripheral tissues and spinal cord. In this study we show that treating mice with the A(2A)R agonist, 4-{3-[6-amino-9-(5-cyclopropylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-piperidine-1-carboxylic acid methyl ester for four days beginning before or just after the onset of reperfusion after compression-induced spinal cord injury rapidly (within 1 day) and persistently (>42 days) reduces locomotor dysfunction and spinal cord demyelination. Protection is abolished in knockout/wild type bone marrow chimera mice selectively lacking the A(2A)R only on bone marrow-derived cells but retaining receptors on other tissues including blood vessels. Paradoxically, reduced spinal cord injury is also noted in A(2A)R -/- mice, and in wild type/knockout bone marrow chimera mice selectively lacking the A(2A)R on non-bone marrow-derived cells, or in mice treated with the A(2A) antagonist, 4-(2-[7-amino-2-[2-furyl][1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl-amino]ethyl)phenol. The greatest protection is seen in knockout/wild type bone marrow chimera mice treated with 4-{3-[6-amino-9-(5-cyclopropylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-piperidine-1-carboxylic acid methyl ester, i.e. by activating the A(2A)R in mice expressing the receptor only in bone marrow-derived cells. The data suggest that inflammatory bone marrow-derived cells are the primary targets of A(2A) agonist-mediated protection. We conclude that A(2A) agonists or other interventions that inhibit inflammation during and after spinal cord ischemia may be effective in reducing spinal cord injury in patients, but excessive or prolonged stimulation of the A(2A)R may be counterproductive. It may be possible to devise strategies to produce optimal spinal cord protection by exploiting temporal differences in A(2A)R-mediated responses.

Altered nociception and morphine tolerance in neuropeptide FF receptor type 2 over-expressing mice.

BACKGROUND: The neuropeptide FF system is thought to act as an anti-opioid modulator and plays a role in nociception, morphine antinociception and dependence. Two receptor subtypes, NPFFR1 and NPFFR2, have been identified, but their respective roles in these processes remain uncertain. METHODS: In the present study, the role of NPFFR2 was investigated using transgenic mice over-expressing NPFFR2 in addition to a NPFFR2 agonist AC-263093. RESULTS: NPFFR2 Tg mice exhibited increased sensitivity to both mechanical and thermal noxious stimuli compared to the WT mice, while the antinociceptive effects of morphine at three different doses (6.25, 12.5 and 25 mg/kg, s.c.) were similar in both strains. The development of tolerance to morphine antinociception after chronic morphine treatment (12.5 mg/kg, s.c.; twice daily × 5 days) was attenuated in NPFFR2 Tg mice when compared to WT mice. Similarly, WT mice receiving AC-263093 pretreatment (2.5 mg/kg, i.p.) showed attenuated morphine tolerance compared to vehicle controls. Most naloxone-precipitated morphine withdrawal symptoms were not attenuated in NPFFR2 Tg mice, with the exception of wet dog shake that was significantly reduced. Both NPFFR2 Tg and WT mice displayed similar degree of morphine rewarding. CONCLUSIONS: Our results suggest that neuropeptide FF R2 is mainly involved in the modulation of nociception and tolerance to morphine antinociception.

ATP sensitive potassium channel and myocardial preconditioning.

KATP channels play an important role in physiology and pathophysiology of many tissues. As in the pancreatic beta cells, they couple the change of blood glucose with insulin release. The data coming from Baukrowitz et al. and Shyng and Nichols gave the possible answers to the two old enigmas of KATP channels, i.e., different ATP sensitivity reported in the same tissue and how the channel opened under intracellular millimolar ATP concentration, in which they showed the lipids and lipid metabolites are essential for KATP channel regulation by altering ATP sensitivity. This new information rises several further considerations. How does PIP2 reduce the sensitivity of the channel to ATP? In order to clarify the possibility of direct competing or allosteric effect on the ATP binding site, competitive binding assay should be performed. Since the PIP2 theory seems to be the key event to determine the ATP sensitivity and thus control the channel open probability, then what is the resting concentration of PIP2 in the cell membrane? Is it sufficient to account for the difference in the ATP sensitivity of the intact cell and excised patch from different tissues? Quantitative studies either immunoblotting by PIP2 antibody or fluorescence-labeled lipid assay-may obtain some basic but useful data for further studies to answer these questions. Furthermore, the ATPi mediated restoration of activity was inhibited by antibodies against PIP2. The dualistic behavior of KATP channels to intracellular NDPs should be reexamined with respect to PIP2. The vast majority of preconditioning studies has been performed in intact animals in which myocardial infarct size was used as the end point to define the cardio-protective effect of ischemic PC. These results suggest a key role for the KATP channel as both a trigger and as an end effector of both acute and delayed ischemic PC. The persistent activation of KATP channels during the early reperfusion phase is essential for a smooth and full recovery of contractile function, as well as for maintenance of electrical stability in heart that has been exposed to ischemia. Though activate adenosine A1 receptor coupled with Gi protein can open the KATP channels, adenosine is quickly released during ischemia and exerts potent coronary vasodilatation to maintain coronary blood flow through A2 receptors. This adenosine-induced coronary vasodilatation could be coupled with KATP channels based on the evidence of the augmentation effect of KCOs. Nitric oxide may also play some role in both first and second window of myocardial protection. It is possible that rapid and reversible phosphorylation and activation of constitutive expressed myocardial NOS or by direct KATP channel phosphorylation and activation leads to the first window of myocardial protection. This hypothesis can be further investigated either by using site direct mutagenesis of iNOS or KATP channel, or by applying the dominant negative iNOS in the cell ischemic model, or by building the adenosine or iNOS knock-out mice to study the relationship of these possible mechanisms. Recently, Kontos further showed that KCOs need L-lysine or L-arginine to dilate cerebral arterioles. This suggests that there may be an amino acid binding site inside the KATP channel and nitric oxide can open the KATP channel either by direct acting on the channel protein or by modulating the affinity of the amino acid binding site for L-lysine or L-arginine. Other KATP channel openers in need of additional characterization are the Type III KCOs (nicorandiol). They open the KATP channel only in the presence of elevated intracellular NDPs, which may make them specifically target to the ischemic region, because the intracellular NDP increases mostly in ischemic region. It is possible that type III KCOs can selectively improve blood flow to ischemic areas without diverting blood away to non-ischemic region, and prevents the "steal phenomenon". (ABSTRACT TRUNCATED)

Intravenous tenoxicam reduces dose and side effects of PCA morphine in patients after thoracic endoscopic sympathectomy.

BACKGROUND: Among surgical modalities for treatment of palmar hyperhidrosis, endoscopic sympathectomy is the most popular choice in recent years. After surgery, the major complaint was anterior chest pain. This study was conducted to evaluate the analgesic efficacy and side effects of tenoxicam (a thienothiazine derivative) in combination with patient-controlled analgesia (PCA) using morphine in patients who received thoracic endoscopic sympathectomy. METHODS: Forty-one ASA class I patients who underwent endoscopic sympathectomy (T2 and T3 ganglia) were randomly divided into two groups. Operation was conducted under general anesthesia with single lumen endotracheal intubation. No narcotic was given during the operation except for fentanyl (3 micrograms/kg) during induction. After surgery, patients in group I received PCA morphine only and patients in group II received PCA morphine plus tenoxicam (20 mg, i.v.) immediately for pain relief. In addition, rescue analgesia with intramuscular meperidine (1 mg/kg) was available to each patient every 4 h prn. The intensity of pain was assessed with VAS pain score every 4 h for 24 h. The frequency of demand and doses of delivered PCA morphine were recorded. RESULTS: Results showed no statistically significant difference between groups in respect of age, body height, body weight and pain scores. However, based upon similar qualitative pain relief, patients in group II revealed less demand for analgesic, less doses of morphine requirement and less side effects. CONCLUSIONS: Tenoxicam may be an effective adjuvant to PCA morphine for postoperative pain control. This combination reduces the total consumption of PCA morphine with less side effects.

A3 adenosine receptor activation triggers phosphorylation of protein kinase B and protects rat basophilic leukemia 2H3 mast cells from apoptosis.

Adenosine accumulates to high levels in inflamed or ischemic tissues and activates A3 adenosine receptors (ARs) on mast cells to trigger degranulation. Here we show that stimulation of rat basophilic leukemia (RBL)-2H3 mast-like cells with the A3 AR agonists N6-(3-iodo)benzyl-5'-N-methylcarboxamidodoadenosine (IB-MECA; 10 nM) or inosine (10 microM) stimulates phosphorylation of protein kinase B (Akt). IB-MECA (1 microM) also causes a >50% reduction in apoptosis caused by exposure of RBL-2H3 cells to UV light. Akt phosphorylation is not stimulated by 100 nM N6-cyclopentyladenosine (A1-selective) or CGS21680 (A2A-selective) and is absent in cells pretreated with wortmannin or pertussis toxin. The KI values of the AR antagonists BW-1433 and 8-sulfophenyltheophylline (8-SPT) were determined in radioligand binding assays for all four subtypes of rat ARs: BW-1433 (A1, 5.8 +/- 1.0 nM; A2A, 240 +/- 37; A2B, 30 +/- 10; A3, 12,300 +/- 3, 700); 8-SPT (A1, 3.2 +/- 1.2 microM; A2A, 57 +/- 4; A2), 2.2 +/- 0.8; A3, >100). BW-1433 and the A3-selective antagonist MRS1523 (5 microM), but not 8-SPT (100 microM), block IB-MECA-induced protection from apoptosis, confirming the A3 AR as the mediator of the antiapoptotic response. The data suggest that adenosine and inosine activate Gi-coupled A3 ARs to protect mast cells from apoptosis by a pathway involving the betagamma subunits of Gi, phosphatidylinositol 3-kinase beta, and Akt. We speculate that activation of A3 ARs on mast cells or other cells that express A3 ARs (e.g., eosinophils) may facilitate their survival and accumulation in inflamed tissues.