Repetitive systemic morphine alters activity‐dependent plasticity of schaffer–collateral–CA1 pyramidal cell synapses: Involvement of adenosine A1 receptors and adenosine deaminase

The effectiveness of O‐pulse stimulation (TPS) for the reversal of O‐pattern primed bursts (PB)‐induced long‐term potentiation (LTP) were examined at the Schaffer–collateral–CA1 pyramidal cell synapses of hippocampal slices derived from rats chronically treated with morphine (M‐T). The results showed that slices derived from both control and M‐T rats had normal field excitatory postsynaptic potential (fEPSP)‐LTP, whereas PS‐LTP in slices from M‐T rats was significantly greater than that from control slices. When morphine was applied in vitro to slices derived from rats chronically treated with morphine, the augmentation of PS‐LTP was not seen. TPS given 30 min after LTP induction failed to reverse the fEPSP‐ or PS‐LTP in both groups of slices. However, TPS delivered in the presence of long‐term in vitro morphine caused the PS‐LTP reversal. This effect was blocked by the adenosine A1 receptor (A1R) antagonist CPX (200 nM) and furthermore was enhanced by the adenosine deaminase (ADA) inhibitor EHNA (10 μM). Interestingly, TPS given 30 min after LTP induction in the presence of EHNA (10 μM) can reverse LTP in morphine‐exposed control slices in vitro. These results suggest adaptive changes in the hippocampus area CA1 in particular in adenosine system following repetitive systemic morphine. Chronic in vivo morphine increases A1R and reduces ADA activity in the hippocampus. Consequently, adenosine can accumulate because of a stimulus train‐induced activity pattern in CA1 area and takes the opportunity to work as an inhibitory neuromodulator and also to enable CA1 to cope with chronic morphine. In addition, adaptive mechanisms are differentially working in the dendrite layer rather than the somatic layer of hippocampal CA1. © 2014 Wiley Periodicals, Inc.     

Adenosine A1 and A2A receptors of hippocampal CA1 region have opposite effects on piriform cortex kindled seizures in rats.

In this study the role of adenosine A1 and A2A receptors of the hippocampal CA1 region on piriform cortex-kindled seizures was investigated in rats. Animals were kindled by daily electrical stimulation of piriform cortex. In fully kindled rats, N6-cyclohexyladenosine (CHA; a selective A1 receptor agonist), 1,3-dimethyl-8-cyclopenthylxanthine (CPT; a selective A1 receptor antagonist), CGS21680 hydrochloride (CGS, a selective A2A receptor agonist) and, ZM241385 (ZM, a selective A2A receptor antagonist) were microinfused bilaterally into the hippocampal CA1 region. Rats were stimulated and seizure parameters were measured. Obtained results showed that microinjection of CHA (10 and 100 microM) decreased the afterdischarge duration (ADD), stage 5 seizure duration (S5D) and seizure duration (SD), and significantly increased the latency to stage 4 (S4L). Intra-hippocampal CPT increased ADD at the dose of 20 microM. Pretreatment of rats with CPT (10 microM) before CHA (10 microM), significantly reduced the effect of CHA on seizure parameters. On the other hand, microinjection of CGS (200 and 500 microM) increased ADD, but of ZM had no effect on seizure parameters. Pretreatment of rats with ZM (50 microM) before CGS (500 microM), significantly reduced the effect of CGS on seizure parameters. The results suggest that the facilitatory role of the hippocampal CA1 region in relaying or spreading of piriform cortex kindled seizures is decreased by the activation of adenosine A1 receptors and increased by A2A receptors.     

Diagnostic and prognostic role of ascitic fluid calprotectin level: six-month outcome findings in cirrhotic patients

Abstract

Aim

To assess the role of ascites calprotectin in early detection of SBP in patients with cirrhosis and to investigate its prognostic value in determination of the 6-month outcome.

Methods and material: In this cross-sectional study, patients with liver cirrhosis who were consecutively referred to Imam Reza hospital, tertiary referral center in the northwest of Iran, underwent abdominal paracentesis. The samples were collected for measurement of calprotectin, albumin, total protein, WBCs, and PMNs.     

Endoscopic findings in a mass screening program for gastric cancer in a high risk region - Guilan province of Iran

Background & Objectives: Gastric cancer is a leading cause of cancer-related deaths in both sexes in Iran. Thisstudy was designed to assess upper GI endoscopic findings among people > 50 years targeted in a mass screeningprogram in a hot-point region. Methods: Based on the pilot results in Guilan Cancer Registry study (GCRS),one of the high point regions for GC –Lashtenesha- was selected. The target population was called mainly usingtwo methods: in rural regions, by house-house direct referral and in urban areas using public media. Upper GIendoscopy was performed by trained endoscopists. All participants underwent biopsies for rapid urea test (RUT)from the antrum and also further biopsies from five defined points of stomach for detection of precancerouslesions. In cases of visible gross lesions, more diagnostic biopsies were taken and submitted for histopathologicevaluation. Results: Of 1,394 initial participants, finally 1,382 persons (702 women, 680 men) with a mean age of61.7±9.0 years (range: 50-87 years) underwent upper GI endoscopy. H. pylori infection based on the RUT waspositive in 66.6%. Gastric adenocarcinoma and squamous cell carcinoma of esophagus were detected in seven(0.5%) and one (0.07%) persons, respectively. A remarkable proportion of studied participants were found tohave esophageal hiatal hernia (38.4%). Asymptomatic gastric masses found in 1.1% (15) of cases which weremostly located in antrum (33.3%), cardia (20.0%) and prepyloric area (20.0%). Gastric and duodenal ulcerswere found in 5.9% (82) and 6.9% (96) of the screened population. Conclusion: Upper endoscopy screening is aneffective technique for early detection of GC especially in high risk populations. Further studies are required toevaluate cost effectiveness, cost benefit and mortality and morbidity of this method among high and moderaterisk population before recommending this method for the GC surveillance program at the national level.     

In vivo sodium salicylate causes tolerance to acute morphine exposure and alters the ability of high frequency stimulation to induce long-term potentiation in hippocampus area CA1

Effects of morphine on synaptic transmission and plasticity in the hippocampus area CA1 following in vivo sodium salicylate and the potential molecular mechanism were investigated. Population spikes (PS) were recorded from stratum pylamidale of area CA1 following stimulation of Schaffer collaterals in slices taken from control and sodium salicylate injected rats. To induce long term potentiation (LTP), a 100Hz tetanic stimulation was used. Acute in vitro morphine increased baseline PS amplitude in control slices but not in slices taken from sodium salicylate treated rats. In vivo chronic salicylate did slightly decrease and/or destabilize LTP of CA1 synaptic transmission. We also found that mRNA of NR2A subunit of NMDA receptor was reduced in the hippocampus of sodium salicylate treated rats as compared to control ones. Following LTP induction, the mRNA of NR2A and PP1 (protein phosphatase 1) in slices taken from salicylate-treated rats were more than those of control ones. After long-term exposure to in vitro morphine, high frequency stimulation (HFS) decreased NR2A mRNA level significantly in sodium salicylate treated slices. It is concluded that in vivo sodium salicylate causes tolerance to excitatory effect of morphine and changes the ability of HFS to induce PS LTP in the hippocampus area CA1 in vitro. These changes in synaptic response may be due to alterations in NR2A and PP1 expression.     

Efficacy of topical phenytoin on chemotherapy-induced oral mucositis; a pilot study

Background and the Purpose of the Study

Oral mucositis is one of the most common complications of malignancy chemotherapy. As yet, no absolute treatment has been demonstrated to be effective for chemotherapy-induced oral mucositis. This study evaluates the effectiveness of phenytoin mouthwash as a wound healing agent, on the basis of stimulating effects on fibroblast proliferation.

Materials and Methods

In this multicenter, randomized, placebo-controlled clinical trial; twelve patients received phenytoin mouthwash (0.5%) or placebo for about two weeks. Oral pain severity was scored on the daily basis using a VAS (visual analogue scale) of 10 centimeters. National Cancer Institute (NCI) scale was used to grade the intensity of mucositis. To determine the effect of treatment, a quality of life questionnaire, consisting of 35 queries, was filled out for all patients. Statistical analyses of data was performed using Mann-Whitney test.

Results

The average time for complete remission of mucositis in phenytoin-treated group was less than that of the placebo group. The quality of life improved dramatically in the phenytoin group with the healing process being more evident in the first week. Furthermore, reduction in the wound area was greater in the phenytoin group than controls at the end of the first week of treatment. Both groups eventually demonstrated reduction in pain intensity; however no statistically significant difference was observed between two groups.

Conclusion

Phenytoin mouthwash accelerated wound healing and resolution of mucositis and improved life quality impressively.     

Epinephrine inhibits analgesic tolerance to intrathecal administrated morphine and increases the expression of calcium-calmodulin-dependent protein kinase IIalpha

Activation of hypothalamic-pituitary-adrenal (HPA) axis inhibits development of morphine tolerance. Also, the expression of CaMKIIalpha is increased following chronic administration of morphine. In the current study, we tried to examine the effect of epinephrine, on the development of morphine tolerance; and also evaluate the expression of CaMKIIalpha as a molecular index for tolerance development. Analgesic tolerance was induced by intrathecal (i.t.) injection of morphine 15 microg/rat, twice a day for 5 days. To study the effect of epinephrine on development or reversal of morphine tolerance, epinephrine was administrated 20 min before morphine injections. Analgesia was assessed using tail flick test. Gene expression assays were done using RT-PCR. Following 5 days of combined administration of morphine and epinephrine (2, 5 or 10 microg/rat), in day 6, morphine produced potent analgesia. Administration of saline and morphine during days 1-5, caused reduced analgesic effect of morphine on day 6. After tolerance induction during 5 days, co-administration of epinephrine and morphine for another 5 days, significantly reversed the tolerance. Both morphine and epinephrine increased the expression of CaMKIIalpha. The expression of CaMKIIalpha was highly increased following combined administration of epinephrine and morphine. Our results showed the inhibition and reversal of analgesic tolerance to local administrated morphine by epinephrine. We observed the increased expression of CaMKIIalpha without development of morphine tolerance in animals treated with combined epinephrine and morphine.     

Cysteamine pre-treatment reduces pentylenetetrazol-induced plasticity and epileptiform discharge in the CA1 region of rat hippocampal slices

The effects of prior treatment of cysteamine, a somatostatin inhibitor, on pentylenetetrazol (PTZ) induced epileptic and plastic changes in CA1 excitability were examined. Population spikes were evoked by activation of Schaffer collaterals with a range of stimulation intensities. Changes in the population spike and epileptiform amplitudes were used as indices to quantify the effects of PTZ exposure in the control and cysteamine pre-treated slices. Cysteamine pre-treatment decreased baseline CA1 population spike amplitude following high intensity stimulation of Schaffer collaterals. Following PTZ application directly to the slices, cysteamine diminished the increased population spike and epileptiform amplitudes which were normally observed following collateral stimulation. Magnesium-free medium induced epileptiform activity was also significantly reduced with cysteamine pre-treatment. It is concluded that somatostatin may be involved in PTZ-induced epileptic and plastic changes in CA1 excitability.     

The effects of acute restraint stress and dexamethasone on retrieval of long-term memory in rats: an interaction with opiate system

This study investigated whether application of acute restraint stress or dexamethasone, as a glucocorticoid receptor agonist, impaired retrieval of long-term memory and if pretreatment with opiate antagonist naloxone blocked their effects on memory retrieval. Young adult male rats were trained in one trial inhibitory avoidance task (1 mA, 1.5 s footshock). On retention test given 48 h after training, the latency to re-enter dark compartment of the apparatus was recorded. Thirty minutes before retention test, the rats were exposed to a 10 min of restraint stress in a Plexiglass tube or were injected with dexamethasone (1 mg/kg) with or without prior treatment of naloxone (1 or 2 mg/kg). The results showed that both acute restraint stress and dexamethasone impaired retention performance. Both doses of naloxone were effective in blocking the impairing effect of stress, but only higher dose of naloxone blocked dexamethasone-induced impairment. The applied stress increased circulating corticosterone levels as assessed immediately after the retention test, indicating that stress-induced impairment of memory retrieval is mediated, in part, by increased plasma levels of glucocorticoids. These findings further indicate that acute restraint stress and glucocorticoids impair retrieval of long-term memory, and provide evidence for the existence of an interaction between glucocortioids and opiate system on this process.