Anti-Inflammatory and Antipruritic Effects of Remote Ischaemic Postconditioning in a Mouse Model of Experimental Allergic Contact Dermatitis.

Background and Objectives: Allergic contact dermatitis is a common type IV hypersensitivity reaction characterised by redness, itching, oedema and thickening of the skin. It occurs in about 7% of the population and its incidence is increasing. It has been observed that the preconditioning of tissues by exposing them to transient ischemia increases resistance to subsequent permanent ischemia, and this phenomenon is called ischemic preconditioning. It has been shown that conditioning in one organ can also protect other organs. The protective effect of remote ischemic preconditioning is thought to be based on the induction of anti-inflammatory responses. The aim of this project was to investigate the anti-inflammatory and antipruritic effects of remote ischemic postconditioning in a mouse model of experimental allergic contact dermatitis. Methods: Experimental allergic contact dermatitis was induced with 1-fluoro-2,4-dinitrobenzene. Remote ischemic postconditioning was performed at 3 and 25 h after the challenge. Ear thickness and number of scratches 24 and 48 h after challenge, as well as cytokine levels and the infiltration of mast cells, neutrophils, CD4+ and CD8+ T lymphocytes in serum and ear tissue at 48 h were measured to determine the effect of RIPsC. Results: Remote ischemic postconditioning decreased ear thickness, one of the symptoms of allergic contact dermatitis (p < 0.0001). It had no significant effect on the number of scratches. It reduced serum IL-17 levels (p < 0.01). It alleviated local inflammation by suppressing CD8+ T lymphocyte and neutrophil infiltration. Conclusions: It was concluded that remote ischemic postconditioning may alleviate the symptoms of allergic contact dermatitis by suppressing CD8+ T lymphocyte and neutrophil infiltration and reducing IL-17 secretion.

The role of endocannabinoid system and TRPV1 receptors in the antidepressant and anxiolytic effects of dipyrone in chronic unpredictable mild stress in mice.

Although dipyrone is a widely used analgesic and antipyretic, its mechanism of action is not fully clarified. Recent studies have drawn attention to its central effects and its relationship with the endocannabinoid system. The endocannabinoid system plays important roles in processes such as anxiety, depression, fear, and learning-memory. In this study, we aimed to investigate whether endocannabinoid levels change in the amygdala in chronic unpredictable mild stress model in mice and whether cannabinoid and TRPV1 receptors mediate antidepressant and anxiolytic effects of dipyrone. Mice were submitted to chronic unpredictable mild stress protocol of 6-weeks, then behavioral test were performed. In the first part of the study, dipyrone was injected at doses of 150, 300, and 600 mg/kg (i.p.) during behavioral tests. In the second part, the CB1 antagonist AM 251 (1 mg/kg, i.p.), the CB2 antagonist AM630 (1 mg/kg, i.p.), and the TRPV1 antagonist capsazepine (3 mg/kg, i.p.) were administered alone or in combination with 300 mg/kg dipyrone to observe if these receptors mediate dipyrone effects. Endocannabinoid and N-acylethanolamines levels were measured by LC-MS/MS in amygdala. Our results showed that there were no changes in AEA, 2-AG, PEA, OAE levels in the amygdala in mice exposed to chronic unpredictable mild stress model; dipyrone exerted antidepressant and anxiolytic effects at doses of 300 and 600 mg/kg; its anxiolytic effect appears to be mediated via CB1 receptors, whereas TRPV1 receptors seems to mediate its antidepressant action.

Non-opioid Analgesics and the Endocannabinoid System

Non-steroidal anti-inflammatory drugs produce antinociceptive effects mainly through peripheral cyclooxygenase inhibition. In opposition to the classical non-steroidal anti-inflammatory drugs, paracetamol and dipyrone exert weak anti-inflammatory activity, their antinociceptive effects appearing to be mostly due to mechanisms other than peripheral cyclooxygenase inhibition. In this review, we classify classical non-steroidal anti-inflammatory drugs, paracetamol and dipyrone as "non-opioid analgesics" and discuss the mechanisms mediating participation of the endocannabinoid system in their antinociceptive effects. Non-opioid analgesics and their metabolites may activate cannabinoid receptors, as well as elevate endocannabinoid levels through different mechanisms: reduction of endocannabinoid degradation via fatty acid amide hydrolase and/or cyclooxygenase-2 inhibition, mobilization of arachidonic acid for the biosynthesis of endocannabinoids due to cyclooxygenase inhibition, inhibition of endocannabinoid cellular uptake directly or through the inhibition of nitric oxide synthase production, and induction of endocannabinoid release.

Effects of hippocampal histone acetylation and HDAC inhibition on spatial learning and memory in the Morris water maze in rats.

In recent years, it has been pointed out that epigenetic changes affect learning and memory formation. Particularly, it has been shown that histone acetylation and DNA methylation work in concert to regulate learning and memory formation. We aimed to examine whether acetylation of H2B within the rat hippocampus alters by trainings in the Morris water maze test. Male, 2-3 months old, Sprague Dawley rats were trained in Morris water maze task. Animals were given four trials per day for five consecutive days to locate a hidden platform. On the sixth day, the platform was removed and the animals were swum for 60 s. The effects of sodium butyrate, histone deacetylase inhibitor, were tested on normal and scopolamine-induced memory-impaired rats. The histone deacetylase inhibitor, sodium butyrate, increased histone H2B acetylation in normal rats. Sodium butyrate had no effect on learning and memory performance of normal rats; however, it partially ameliorated learning and memory disruption induced by scopolamine. So, the histone deacetylase inhibitors can be new treatment agent for cognitive disorders.

Endocannabinoid and N-acylethanolamide levels in rat brain and spinal cord following systemic dipyrone and paracetamol administration.

The cannabinoid system has been suspected to play a role in the mechanisms of action of dipyrone and paracetamol. Our purpose was to measure the local endocannabinoid and N-acylethanolamide levels in the brain and spinal cord of rats following dipyrone and paracetamol administration. Nociception was assessed 1, 5, and 12 h following drug injections in Wistar rats, using tail-flick and hot-plate tests. The antinociceptive effects of dipyrone (150, 300, and 600 mg/kg, i.p.) and paracetamol (30, 100, and 300 mg/kg, i.p.) were observed. After administration of the highest doses of dipyrone and paracetamol, endocannabinoid (N-arachidonoylethanolamide (AEA), 2-arachidonoylglycerol (2-AG)) and N-acylethanolamide (palmitoylethanolamide (PEA), oleoylethanolamide (OEA)) levels were measured in the periaqueductal gray (PAG), rostral ventromedial medulla (RVM), and spinal cords of rats using tandem mass spectrometry with liquid chromatography. Increased 2-AG levels were observed in the PAG and the RVM 12 h after paracetamol injection; dipyrone exerted no action on 2-AG levels. Analgesic administrations led to a reduction in AEA levels in the RVM and spinal cord; similar decreases in PEA and OEA levels were observed in the RVM and the spinal cord. Dipyrone and paracetamol administrations appear to exert complicated effects on endocannabinoid and N-acylethanolamide levels in rats.

Effects of in vitro Amitriptyline, Fluoxetine, Tranylcypromine and Venlafaxine on Saphenous Vein Grafts.

OBJECTIVE: In this study, we aimed to examine the effects of amitriptyline, fluoxetine, tranylcypromine and venlafaxine on saphenous vein grafts in coronary artery bypass graft surgeries. METHODS: 59 patients (40 males and 19 females; mean age 65.1 years, distribution: 45-84 years) who had coronary artery bypass graft surgery between February 2014 and May 2016 were included in the study. After the saphenous vein grafts with intact and denuded endothelium were precontracted with 3×10-6M phenylephrine, amitriptyline, fluoxetine and tranylcypromine were cumulatively added to isolated organ baths in the range of 10-11-3x10-5M, while venlafaxine was added in the range of 10-9-3×10-5M. Then, the antidepressant-induced relaxation responses were recorded isometrically. RESULTS: While the relaxation response of amitriptyline at -6.42 (Log M) was 74.6%, the response at -6.32 (Log M) was 75.5%. While the relaxation response at -6.46 (Log M) of fluoxetine was 68.02%, the response at -6.02 (Log M) was 72.12%. While the relaxation response of tranylcypromine at -7.53 (Log M) was 61.13%, the response at -7.23 (Log M) was 65.53%. While the relaxation response of venlafaxine at -6.21 (Log M) was 29.98%, the response at -5.90 (Log M) was 32.96%. CONCLUSION: The maximum relaxation at minimum and maximum therapeutic concentrations was obtained with amitriptyline, fluoxetine and tranylcypromine, and the minimum relaxation was obtained with venlafaxine. The relaxation responses were independent of the endothelium.

Effects of in vitro amitriptyline, fluoxetine, tranylcypromine and venlafaxine on saphenous vein grafts

Abstract Objective: In this study, we aimed to examine the effects of amitriptyline, fluoxetine, tranylcypromine and venlafaxine on saphenous vein grafts in coronary artery bypass graft surgeries. Methods: 59 patients (40 males and 19 females; mean age 65.1 years, distribution: 45-84 years) who had coronary artery bypass graft surgery between February 2014 and May 2016 were included in the study. After the saphenous vein grafts with intact and denuded endothelium were precontracted with 3×10-6M phenylephrine, amitriptyline, fluoxetine and tranylcypromine were cumulatively added to isolated organ baths in the range of 10-11-3x10-5M, while venlafaxine was added in the range of 10-9-3×10-5M. Then, the antidepressant-induced relaxation responses were recorded isometrically. Results: While the relaxation response of amitriptyline at -6.42 (Log M) was 74.6%, the response at -6.32 (Log M) was 75.5%. While the relaxation response at -6.46 (Log M) of fluoxetine was 68.02%, the response at -6.02 (Log M) was 72.12%. While the relaxation response of tranylcypromine at -7.53 (Log M) was 61.13%, the response at -7.23 (Log M) was 65.53%. While the relaxation response of venlafaxine at -6.21 (Log M) was 29.98%, the response at -5.90 (Log M) was 32.96%. Conclusion: The maximum relaxation at minimum and maximum therapeutic concentrations was obtained with amitriptyline, fluoxetine and tranylcypromine, and the minimum relaxation was obtained with venlafaxine. The relaxation responses were independent of the endothelium.

Descending serotonergic and noradrenergic systems do not regulate the antipruritic effects of cannabinoids.

BACKGROUND: For centuries, cannabinoids have been known to be effective in pain states. Itch and pain are two sensations sharing a lot in common. OBJECTIVE: The goal of this research was to observe whether the cannabinoid agonist WIN 55,212-2 reduces serotonin-induced scratching behaviour and whether neurotoxic destruction of descending serotonergic and noradrenergic pathways mediate the antipruritic effect of WIN 55,212-2. Material and methods Scratching behaviour was induced by intradermal injection of serotonin (50 µg/50 µl/mouse) to Balb/c mice. The neurotoxins 5,7-dihydroxytryptamine (5,7-DHT, 50 µg/mouse) and 6-hydroxydopamine (6-OHDA, 20 µg/mouse) are applied intrathecally to deplete serotonin and noradrenaline in the spinal cord. WIN 55,212-2 (1, 3, 10 mg/kg, i.p.) dose-dependently attenuated serotonin-induced scratches. Neurotoxic destruction of neither the serotonergic nor the noradrenergic systems by 5,7-DHT and 6-OHDA, respectively, had any effect on the antipruritic action of WIN 55,212-2. CONCLUSION: Our findings indicate that cannabinoids dose-dependently reduce serotonin-induced scratching behaviour and neurotoxic destruction of descending inhibitory pathways does not mediate this antipruritic effect.

Hemodynamic effects of atrial natriuretic peptide in ischemia-repertusion injury that occurs after exercise.

BACKGROUND/AIM: Atrial natriureticpeptide (ANP) is known as a protective agent against ischemia-reperfusion injuryfor cardiomyocytes. We compared the hemodynamic effects of ANP and isatin, which is known as an ANP receptor blocker, in ischemia followed by reperfusion in exercised rat hearts with nonexercised ones. MATERIALS AND METHODS: Isolated hearts were perfused in 4 exercised (E) groups after a running protocol for 5 days and 4 nonexercised (NE) groups. In the first protocol, ANP was added to the perfusion solution before ischemia in an E and NE group. In the second protocol, different doses of isatin (0.1, 10, 100 µM/L) were added to the perfusion solution before ANP in 3 E and 3 NE groups. Left ventricular developed pressure (LVDP) and maximum and minimum rates of change in left ventricular pressure (dP/dtmax and dP/dtmin) were recorded. RESULTS: Higher LVDP and dP/dtmin values were observed in the E group than the NE group following addition of ANP before ischemia. Values of dP/dtmax were higher in the E group at the first minute of reperfusion period. Hemodynamic difference was not observed between groups given the same amount of isatin before ANP. CONCLUSION: This study indicated that higher ANP concentrations before ischemia were more effective on the left ventricle contractility and relaxation functions in the hearts that were exposed to exercise.

The Protective Effect of Curcumin on Ionizing Radiation-induced Cataractogenesis in Rats.

OBJECTIVE: The aim of the study was to determine the protective effect of curcumin against ionizing radiation-induced cataract in the lens of rats. MATERIAL AND METHODS: Rats were divided into six groups. Group 1: Control, Group 2: Dimethyl sulfoxide (DMSO), Group 3: DMSO+curcumin, Group 4: Irradiation, Group 5: Irradiation+DMSO, Group 6: Irradiation+DMSO+curcumin. A 15 Gy total dose was given to 4, 5, 6 groups for radiation damage. Curcumin (100 mg/kg) was dissolved in DMSO and given by intragastric intubation for 28 days. At the end of the experiment, lenses were graded and enucleated. The lenticular activity of the antioxidant enzymes, total antioxidant and glutathione peroxidase (GSH-Px), and the malondialdehyde (MDA) were measured. RESULTS: 100% Cataract was seen in the irradiation group. Cataract rate fell to 40% and was limited at grade 1 and 2 in the curcumin group. In the irradiation group, antioxidant enzyme levels were decreased, MDA levels were increased. There was an increase in antioxidant enzyme levels and a significant decrease in MDA in the group which was given curcumin. CONCLUSION: Curcumin has antioxidant and radioprotective properties and is likely to be a valuable agent for protection against ionizing radiation. Hence, it may be used as an antioxidant and radioprotector against radiation-induced cataractogenesis.

Modulatory role of the endogenous nitric oxide synthase inhibitor, asymmetric dimethylarginine (ADMA), in morphine tolerance and dependence in mice.

Elevated plasma asymmetric dimethylarginine (ADMA) levels have been implicated in many cardiovascular and metabolic disorders. In the current work, we investigated the hypothesis that peripheral ADMA is an important contributor to opioid tolerance and dependence, by determining plasma ADMA levels during the development of tolerance and dependence to morphine in mice. Tolerance to and dependence on morphine were induced by repeated injections of morphine (10 mg/kg, s.c.) twice daily to male mice, divided into groups of 3-, 6-, 9- and 10-day injection duration. The loss of antinociceptive effect of morphine in the tail flick test was used for evaluating the degree of tolerance. Physical dependence was assessed following the administration of a 5 mg/kg dose of naloxone, by counting the occurrence of withdrawal jumps and forepaw tremors for 20 min. At the end of each period, animals were anesthetized and blood samples were collected from carotid artery. The plasma levels of ADMA, symmetric dimethylarginine (SDMA), L: -homoarginine and L: -arginine in morphine-tolerant and -dependent mice were not different from duration-matched control mice. Similarly, no difference was observed in plasma ADMA and the other molecules concentrations between groups of mice with different stages of development of tolerance and dependence. Our results suggest that endogenous plasma ADMA, SDMA, L: -homoarginine and L: -arginine levels remain unchanged during the development of morphine tolerance and dependence, and are not associated with these phenomena.