Neuroaxonal and cellular damage/protection by prostanoid receptor ligands,fatty acid derivatives and associated enzyme inhibitors

Cellular and mitochondrial membrane phospholipids provide the substrate for synthesis and release of prostaglandins in response to certain chemical,mechanical,noxious and other stimuli.Prostaglandin D_(2),prostaglandin E_(2),prostaglandin F_(2)α,prostaglandin I_(2)and thromboxane-A_(2)interact with five major receptors(and their sub-types)to elicit specific downstream cellular and tissue actions.In general,prostaglandins have been associated with pain,inflammation,and edema when they are present at high local concentrations and involved on a chronic basis.However,in acute settings,certain endogenous and exogenous prostaglandins have beneficial effects ranging from mediating muscle contraction/relaxation,providing cellular protection,regulating sleep,and enhancing blood flow,to lowering intraocular pressure to prevent the development of glaucoma,a blinding disease.Several classes of prostaglandins are implicated(or are considered beneficial)in certain central nervous system dysfunctions(e.g.,Alzheimer’s,Parkinson’s,and Huntington’s diseases;amyotrophic lateral sclerosis and multiple sclerosis;stroke,traumatic brain injuries and pain)and in ocular disorders(e.g.,ocular hypertension and glaucoma;allergy and inflammation;edematous retinal disorders).This review endeavors to address the physiological/pathological roles of prostaglandins in the central nervous system and ocular function in health and disease,and provides insights towards the therapeutic utility of some prostaglandin agonists and antagonists,polyunsaturated fatty acids,and cyclooxygenase inhibitors.

Tolerance of neurite outgrowth to Rho kinase inhibitors decreased by cyclooxygenase-2 inhibitor

In this study, PC12 Adh cells and Neuro-2a cells were treated with Rho-associated kinase inhibitors （Y27632 and Fasudil）, a cyclooxygenase-1 selective inhibitor （SC560）, and a cyclooxygenase-2 inhibitor （NS398）. We found that these cells became tolerant to Rho-associated kinase inhibitors, as neurite outgrowth induced by these inhibitors diminished following more than 3 days of exposure in either cell line. The proteins cyclooxygenase-2 and cytosolic prostaglandin E synthetase were upregulated at day 3. NS398 decreased the tolerance to neurite outgrowth induction in both cell lines, whereas SC560 had almost no effect. These findings indicate that cells become tolerant to neurite outgrowth induced by Rho-associated kinase inhibitors, this is at least partly associated with upregulation of proteins involved in the cyclooxygenase-2 pathway, and cyclooxygenases-2 inhibition prevents this tolerance.

Effects of cyclooxygenase 2 inhibitor on growth-associated protein 43 and nerve growth factor expression in dorsal root ganglion during neuropathic pain development

BACKGROUND： Inflammatory responses in injured nerves have been recognized as important factors for initially sensitizing nociceptive neurons. Cyclooxygenase （COX） is the rate-limiting enzyme in prostaglandin synthesis, and COX-2 inhibitor is involved in mechanisms of analgesia and anti-inflammation. OBJECTIVE： To investigate the effects of COX-2 inhibitor on thermal and mechanical hyperalgesia, as well as expression of growth associated protein 43 （GAP-43） and nerve growth factor （NGF） in dorsal root ganglion, in a rat model of neuropathic pain due to chronic constriction injury. DESIGN, TIME AND SETTING： A randomized, controlled, comparison study that was performed at the Surgical Department and Pathological Laboratory, Second Affiliated Hospital of Shantou University Medical College from September 2006 to September 2007. MATERIALS： COX-2 inhibitor, Iornoxicam, was purchased from Nycomed Pharmaceutical （Austria）; rabbit anti-GAP-43, and rabbit anti-NGF polyclonal antibodies were purchased from Boster, Wuhan, China. METHODS： A total of 50 adult, Wistar rats were randomly assigned to four groups： normal control （n = 5）, model （n = 15）, normal saline control （n = 15）, and Iornoxicam treatment （n =15）. With exception of the control group, the sciatic nerve of all rats was loosely ligated to establish a model of chronic constriction injury. The model rats were divided into three subgroups according to varying post-operative survival periods： 3, 7 and 14 days （n = 5）, respectively. Rats in the Iornoxicam treatment group were intraperitoneally injected with 1.3 mg/kg lornoxicam every 12 hours throughout the entire experimental procedure. Rats in the normal saline control group were intraperitoneally injected with 1.3 mL/kg saline. MAIN OUTCOME MEASURES： Immunohistochemistry revealed expression of GAP-43 and NGF in the L5 dorsal root ganglions. Mechanical withdrawal threshold and thermal withdrawal latency were used to observe neurological behavioral changes in rats. RESULTS： The relative gray values of GAP-43- and NGF-positive neurons in the model group were remarkably increased compared with the normal control rats （P 〈 0.01）, while the relative gray values in the Iomoxicam treatment group were significantly less than the model and normal saline control groups （P 〈 0.01）. Mechanical withdrawal threshold and thermal withdrawal latency gradually decreased with increasing injury time in the model, normal saline control, and Iornoxicam treatment groups, and were significantly less than the normal control group （P 〈 0.05）. In addition, mechanical withdrawal threshold and thermal withdrawal latency were significantly greater in the Iornoxicam treatment group compared with the model and normal saline control groups （P 〈 0.05）. CONCLUSION： Intraperitoneal injection of the COX-2 inhibitor Iornoxicam attenuated mechanical and thermal hyperalgesia induced by sciatic nerve chronic constriction injury and inhibited the increased expression of GAP-43 and NGF.

Analgesic effect of parecoxib and flurbiprofen axetil for patients undergoing laparoscopic cholecystectomy and their influences on platelet aggregation

It is known that opioids produce postoperative analgesia, while it can also cause, especially in large doses, side effects like nausea, vomiting, constipation, syncope, skin itching, urinary retention and even respiratory inhibition. These factors have all greatly limited its clinical use for treating postoperative pain. Meanwhile, non-steroidal anti-inflammatory drugs （NSAIDs） play an increasingly important role in postoperative analgesia. Some studies suggest that NSAIDS may be neural protective in cerebral ischemic conditions.

Efficacy and safety of perioperative parecoxib for acute postoperative pain treatment in children： a meta-analysis

Perioperative parecoxib administration reduces postoperative pain, opioid consumption, and adverse events in adult patients. However, the efficacy and safety of parecoxib in children remain unclear. This meta-analysis included related published studies to address this concern. Eight databases in the literature until February 2015 were systematically explored to identify randomized controlled trials （RCTs） comparing perioperative parecoxib administration and placebo/standard treatments for acute postoperative pain in children. Primary outcomes were postoperative pain scores and adverse events. The Face, Legs, Activity, Crying, Consolability scale was used to score pain in children younger than 6 years, whereas the Visual Analog Scale was used in children older than 6 years. Secondary outcomes were sedation scores （measured using the Ramsay scale）, agitation scores （measured using the Sedation-Agitation Scale）, and opioid consumption. The methodological quality of RCTs was independently assessed in accordance with the ＂Risk of bias＂ of Cochrane Collaboration. Data were analyzed using Review Manager 5.2. Twelve RCTs involving 994 patients met the inclusion criteria. Compared with children who received placebo treatment, those who received parecoxib demonstrated lower early （2 h） and later （12 h） postoperative pain scores; lower incidence rates of postoperative nausea, vomiting, and agitation; higher early （1 h） postoperative sedation scores; and lower agitation scores. Similarly, children who received parecoxib had lower early （2 h） and later （12 h） postoperative pain scores, lower incidence rates of postoperative nausea and vomiting, and lower early （1 h） postoperative sedation scores compared with those who received standard treatments; however, these children showed no significant difference in agitation scores. Unfortunately, data on the effect of parecoxib on opioid consumption were insufficient. Overall, these results suggested that perioperative parecoxib administration was associated with less acute postoperative pain and fewer adverse events compared with placebo or standard treatments. Parecoxib administration also resulted in less emergence agitation compared with placebo treatment and less excessive sedation concern compared with standard treatments. However, the long-term effects, effects on opioid consumption, and patient satisfaction of parecoxib administration warrant further investigation.