Effects of the Agents Influencing the Serotonergic and Cannabinoid Systems on Memory in the Avoidance Test in Mice

Adult male albino mice in a shuttle box system were used for examination of learning for avoidance behavior and its deactivation. We measured the step-through latency in the acquisition of the task (STLa) before injections of the drugs tested (fluoxetine and URB597 (a serotonin reuptake inhibitor, SSRI, and an agent preventing decomposition of endocannabinoids, respectively) and the respective latency 24 h later after injections of these agents (STLr); total time spent in the dark compartment (TDC) was also measured in these situations. In mice that received fluoxetine (5, 10, and 20 mg/kg), the STLr were longer than those in the control, and the difference was significant at 10 mg/kg. Injections of URB597 decreased the STLr and, at medium and high doses (0.3 and 1.0 mg/kg), provided significant differences. All doses of fluoxetine led to significant decreases in the TDC values, while injections of URB597 increased this index (at 0.3 and 1.0 mg/kg, the shifts were significant). Combined injections of fluoxetine and URB597 (5 + 0.1, 10 + 0.3, and 20 + 1.0 mg/kg) increased the STLr values and decreased TDC values to the levels comparable with those at isolated injections of fluoxetine in the respective doses. Thus, fluoxetine improved memory, while URB597 impaired it; fluoxetine is capable of nullifying negative effects of URB597.У дорослих білих мишей-самців досліджували навчання поведінці уникання та деактивацію цього процесу в системі із човниковою камерою. Виміряли латентні періоди перетину межі при навчанні дó ін’єкції тестованих агентів – флуоксетину (інгібітора зворотного захоплення серотоніну, SSRS) та URB597 (речовини, що перешкоджає декомпозиції ендоканабіноїдів) і після таких ін’єкцій (STLa і STLr) відповідно; визначали також загальний час, проведений у темному компартменті в даних ситуаціях (TDC). У мишей, які отримували флуоксетин (5, 10 або 20 мг/кг), STLr ставали більшими, ніж у контролі, причому в разі використання 10 мг/кг різниця середніх була вірогідною. Ін’єкції URB597 зменшували значення TDC, і при середніх і високих дозах (0.3 і 1.0 мг/кг) відмінності перевищували рівень вірогідності. Флуоксетин у всіх дозах зумовлював істотне зменшення значень TDC, а ін’єкції URB597 збільшували цей показник (при 0.3 та 1.0 мг/кг зрушення були вірогідними). Комбіновані ін’єкції флуоксетину та URB597 (5 + 0.1, 10 + 0.3 і 20 + + 1.0 мг/кг) призводили до збільшення значень STLr і зменшення TDC до рівнів, порівнянних із тими, які спостерігалися в умовах ізольованих уведень флуоксетину у відповідних дозах. Таким чином, флуоксетин покращував пам’ять, тоді як URB597 порушував її; флуоксетин має здатність нейтралізувати негативні ефекти URB597

Reduction–oxidation (redox) system in radiation-induced normal tissue injury: molecular mechanisms and implications in radiation therapeutics

Every year, millions of cancer patients undergo radiation therapy for treating and destroying abnormal cell growths within normal cell environmental conditions. Thus, ionizing radiation can have positive therapeutic effects on cancer cells as well as post-detrimental effects on surrounding normal tissues. Previous studies in the past years have proposed that the reduction and oxidation metabolism in cells changes in response to ionizing radiation and has a key role in radiation toxicity to normal tissue. Free radicals generated from ionizing radiation result in upregulation of cyclooxygenases (COXs), nitric oxide synthase (NOSs), lipoxygenases (LOXs) as well as nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), and their effected changes in mitochondrial functions are markedly noticeable. Each of these enzymes is diversely expressed in multiple cells, tissues and organs in a specific manner. Overproduction of reactive oxygen radicals (ROS), reactive hydroxyl radical (ROH) and reactive nitrogen radicals (RNS) in multiple cellular environments in the affected nucleus, cell membranes, cytosol and mitochondria, and other organelles, can specifically affect the sensitive and modifying enzymes of the redox system and repair proteins that play a pivotal role in both early and late effects of radiation. In recent years, ionizing radiation has been known to affect the redox functions and metabolism of NADPH oxidases (NOXs) as well as having destabilizing and detrimental effects on directly and indirectly affected cells, tissues and organs. More noteworthy, chronic free radical production may continue for years, increasing the risk of carcinogenesis and other oxidative stress-driven degenerative diseases as well as pathologies, in addition to late effect complications of organ fibrosis. Hence, knowledge about the mechanisms of chronic oxidative damage and injury in affected cells, tissues and organs following exposure to ionizing radiation may help in the development of treatment and management strategies of complications associated with radiotherapy (RT) or radiation accident victims. Thus, this medically relevant phenomenon may lead to the discovery of potential antioxidants and inhibitors with promising results in targeting and modulating the ROS/NO-sensitive enzymes in irradiated tissues and organ injury systems

Melatonin Attenuates Upregulation of Duox1 and Duox2 and Protects against Lung Injury following Chest Irradiation in Rats

Objective: The Lung is one of the most radiosensitive organs of the body. The infiltration of macrophages and lymphocytes into the lung is mediated via the stimulation of T-helper 2 cytokines such as IL-4 and IL-13, which play a key role in the development of fibrosis. It is likely that these cytokines induce chronic oxidative damage and inflammation through the upregulation of Duox1 and Duox2, which can increase the risk of late effects of ionizing radiation (IR) such as fibrosis and carcinogenesis. In the present study, we aimed to evaluate the possible increase of IL-4 and IL-13 levels, as well as their downstream genes such as IL4ra1, IL13ra2, Duox1, and Duox2. Materials and Methods: In this experimental animal study, male rats were divided into 4 groups: i. Control, ii. Melatonin-treated, iii. Radiation, and iv. Melatonin (100 mg/kg) plus radiation. Rats were irradiated with 15 Gy 60Co gamma rays and then sacrificed after 67 days. The expressions of IL4ra1, IL13ra2, Duox1, and Duox2, as well as the levels of IL-4 and IL-13, were evaluated. The histopathological changes such as the infiltration of inflammatory cells, edema, and fibrosis were also examined. Moreover, the protective effect of melatonin on these parameters was also determined. Results: Results showed a 1.5-fold increase in the level of IL-4, a 5-fold increase in the expression of IL4ra1, and a 3-fold increase in the expressions of Duox1 and Duox2. However, results showed no change for IL-13 and no detectable expression of IL13ra2. This was associated with increased infiltration of macrophages, lymphocytes, and mast cells. Melatonin treatment before irradiation completely reversed these changes. Conclusion: This study has shown the upregulation of IL-4-IL4ra1-Duox2 signaling pathway following lung irradiation. It is possible that melatonin protects against IR-induced lung injury via the downregulation of this pathway and attenuation of inflammatory cells infiltration. © 2019 Royan Institute (ACECR). All rights reserved

Targeting of inflammation for radiation protection and mitigation

Background: Inflammation is the response of the immune system that guards the body against several harmful stimuli in normal conditions. However, in response to ionizing radiation that leads to a massive cell death and DNA aberrations, this phenomenon causes various side effects in normal tissues. Inflammation is involved in various side effects such as gastrointestinal toxicity, mucositis, skin reactions, nervous system damage, pneumonitis, fibrosis and so on. Discussion: Observations have proposed that inflammatory mediators are involved in the toxic effect of ionizing radiation on non-irradiated cells via a phenomenon named bystander effect. Inflammation in both irradiated and non-irradiated cells can trigger genomic instability, leading to increased risk of carcinogenesis. Targeting the inflammatory mediators has been an interesting idea for improving the therapeutic ratio throughout the reduction of normal tissue injury as well as an increase in tumor response to radiotherapy. Conclusion: So far, various targets have been proposed for the amelioration of radiation toxicity in radiotherapy. Of different targets, NF-κB, COX-2, some of NADPH Oxidase subfamilies, TGF-β, p38 and the renin-angiotensin system have shown promising results. Interestingly, inhibition of these targets can help sensitize the tumor cells to the radiation treatment with some mechanisms such as suppression of angiogenesis and tumor growth as well as induction of apoptosis. In this review, we focus on recent advances on promising studies for targeting the inflammatory mediators in radiotherapy. © 2018 Bentham Science Publishers

COX-2 in radiotherapy: A potential target for radioprotection and radiosensitization

Background: Each year, millions of people die from cancer. Radiotherapy is one of the main treatment strategies for cancer patients. Despite the beneficial roles of treatment with radiation, several side effects may threaten normal tissues of patients in the years after treatment. Discussion: Moreover, high incidences of second primary cancers may reduce therapeutic ratio of radiotherapy. The search for appropriate targets of radiosensitization of tumor cells as well as radioprotection of normal tissues is one of the most interesting aims in radiobiology. Cyclooxygenase-2 (COX-2), as an inflammatory mediator has attracted interests for both aims. COX-2 activity is associated with ROS production and inflammatory signs in normal tissues. These effects further amplify radiation toxicity in irradiated cells as well as adjacent cells through a phenomenon known as Bystander effect. Increased COX-2 expression in distant non-irradiated tissues causes oxidative DNA damage and elevated cancer risk. Moreover, in tumors, the activation of this enzyme can increase resistance of malignant cells to radiotherapy. Hence, the inhibition of COX-2 has been proposed for better therapeutic response and amelioration of normal tissues. Celecoxib is one of the most studied COX-2 inhibitor for radiosensitization and radioprotection, while some other inhibitors have shown interesting results. Conclusion: In this review, we describe the role of COX-2 in radiation normal tissue injury as well as irradiated bystander and non-targeted cells. In addition, mechanisms of COX-2 induced tumor resistance to radiotherapy and the potential role of COX-2 inhibition are discussed. © 2018 Bentham Science Publishers

Reduction�oxidation (redox) system in radiation-induced normal tissue injury: molecular mechanisms and implications in radiation therapeutics

Abstract Every year, millions of cancer patients undergo radiation therapy for treating and destroying abnormal cell growths within normal cell environmental conditions. Thus, ionizing radiation can have positive therapeutic effects on cancer cells as well as post-detrimental effects on surrounding normal tissues. Previous studies in the past years have proposed that the reduction and oxidation metabolism in cells changes in response to ionizing radiation and has a key role in radiation toxicity to normal tissue. Free radicals generated from ionizing radiation result in upregulation of cyclooxygenases (COXs), nitric oxide synthase (NOSs), lipoxygenases (LOXs) as well as nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), and their effected changes in mitochondrial functions are markedly noticeable. Each of these enzymes is diversely expressed in multiple cells, tissues and organs in a specific manner. Overproduction of reactive oxygen radicals (ROS), reactive hydroxyl radical (ROH) and reactive nitrogen radicals (RNS) in multiple cellular environments in the affected nucleus, cell membranes, cytosol and mitochondria, and other organelles, can specifically affect the sensitive and modifying enzymes of the redox system and repair proteins that play a pivotal role in both early and late effects of radiation. In recent years, ionizing radiation has been known to affect the redox functions and metabolism of NADPH oxidases (NOXs) as well as having destabilizing and detrimental effects on directly and indirectly affected cells, tissues and organs. More noteworthy, chronic free radical production may continue for years, increasing the risk of carcinogenesis and other oxidative stress-driven degenerative diseases as well as pathologies, in addition to late effect complications of organ fibrosis. Hence, knowledge about the mechanisms of chronic oxidative damage and injury in affected cells, tissues and organs following exposure to ionizing radiation may help in the development of treatment and management strategies of complications associated with radiotherapy (RT) or radiation accident victims. Thus, this medically relevant phenomenon may lead to the discovery of potential antioxidants and inhibitors with promising results in targeting and modulating the ROS/NO-sensitive enzymes in irradiated tissues and organ injury systems. Keywords Radiation Redox Normal tissue injury Inflammation NADPH oxidas

Stem Cell Tracing Through MR Molecular Imaging

Abstract Stem cell therapy opens a new window in medicine to overcome several diseases that remain incurable. It appears such diseases as cardiovascular disorders, brain injury, multiple sclerosis, urinary system diseases, cartilage lesions and diabetes are curable with stem cell transplantation. However, some questions related to stem cell therapy have remained unanswered. Stem cell imaging allows approval of appropriated strategies such as selection of the type and dose of stem cell, and also mode of cell delivery before being tested in clinical trials. MRI as a non-invasive imaging modality provides proper conditions for this aim. So far, different contrast agents such as superparamagnetic or paramagnetic nanoparticles, ultrasmall superparamagnetic nanoparticles, fluorine, gadolinium and some types of reporter genes have been used for imaging of stem cells. The core subject of these studies is to investigate the survival and differentiation of stem cells, contrast agent’s toxicity and long term following of transplanted cells. The promising results of in vivo and some clinical trial studies may raise hope for clinical stem cells imaging with MRI. Keywords: Stem cell, MRI, Molecular imaging, Regenerative medicine, Cell therap

Metformin protects against radiation-induced heart injury and attenuates the upregulation of dual oxidase genes following Rat's chest irradiation

Radiation-induced heart toxicity is one of the serious side effects after a radiation disaster or radiotherapy for patients with chest cancers, leading to a reduction in the quality of life of the patients. Evidence has shown that infiltration of inflammatory cells plays a key role in the development of functional damages to the heart via chronic upregulation of some pro-fibrotic and pro-inflammatory cytokines. These changes are associated with continuous free radical production and increased stiffness of heart muscle. IL-4 and IL-13 are two important pro-fibrotic cytokines which contribute to the side effects of ionizing radiation exposure. Recent studies have proposed that IL-4 through upregulation of DUOX2, and IL-13 via stimulation of DUOX1 gene expression, are involved in the development of radiation late effects. In the present study, we aimed to detect changes in the expression of these pathways following irradiation of rat's heart. Furthermore, we evaluated the possible protective effect of metformin on the development of these abnormal changes. 20 male rats were divided into 4 groups (control, radiation, metformin treated, metformin + radiation). These rats were irradiated with 15 Gy 60 Co gamma rays, and sacrificed after 10 weeks for evaluation of the changes in the expression of IL4R1, IL-13R2a, DUOX1 and DUOX2. In addition, the levels of IL-4 and IL-13 cytokines, as well as infiltration of macrophages and lymphocytes were detected. Results showed an upregulation of both DUOX1 and DUOX2 pathways in the presence of metformin, while the level of IL-13 did not show any significant change. This was associated with infiltration of macrophages and lymphocytes. Also, treatment with metformin could significantly attenuate accumulation of inflammatory cells, and upregulate these pathways. Therefore, suppression of dual oxidase genes by metformin may be a contributory factor to its protective effect. © 2018, Babol University of Medical Sciences

Metformin protects against radiation-induced pneumonitis and fibrosis and attenuates upregulation of dual oxidase genes expression

Purpose: Lung tissue is one of the most sensitive organs to ionizing radiation (IR). Early and late side effects of exposure to IR can limit the radiation doses delivered to tumors that are within or adjacent to this organ. Pneumonitis and fibrosis are the main side effects of radiotherapy for this organ. IL-4 and IL-13 have a key role in the development of pneumonitis and fibrosis. Metformin is a potent anti-fibrosis and redox modulatory agent that has shown radioprotective effects. In this study, we aimed to evaluate possible upregulation of these cytokines and subsequent cascades such as IL4-R1, IL-13R1, Dual oxidase 1 (DUOX1) and DUOX2. In addition, we examined the potential protective effect of metformin in these cytokines and genes, as well as histopathological changes in rat�s lung tissues. Methods: 20 rats were divided into 4 groups: control; metformin treated; radiation + metformin; and radiation. Irradiation was performed with a 60 Co source delivering 15 Gray (Gy) to the chest area. After 10 weeks, rats were sacrificed and their lung tissues were removed for histopathological, real-time PCR and ELISA assays. Results: Irradiation of lung was associated with an increase in IL-4 cytokine level, as well as the expression of IL-4 receptor-a1 (IL4ra1) and DUOX2 genes. However, there was no change in the level of IL-13 and its downstream gene including IL-13 receptor-a2 (IL13ra2). Moreover, histopathological evaluations showed significant infiltration of lymphocytes and macrophages, fibrosis, as well as vascular and alveolar damages. Treatment with metformin caused suppression of upregulated genes and IL-4 cytokine level, associated with amelioration of pathological changes. Conclusion: Results of this study showed remarkable pathological damages, an increase in the levels of IL-4, IL4Ra1 and Duox2, while that of IL-13 decreased. Treatment with metformin showed ability to attenuate upregulation of IL-4�DUOX2 pathway and other pathological damages to the lung after exposure to a high dose of IR. © 2018 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers

Radiation-induced dual oxidase upregulation in rat heart tissues: Protective effect of melatonin

Background: Radiation-induced heart injury can lead to increased risk of heart failure, attack, and ischemia. Some studies proposed IL-4 and IL-13 as two important cytokines that are involved in late effects of ionizing radiation. On the other hand, these cytokines may, through upregulation of Duox1 and Duox2, induce chronic oxidative stress, inflammation, and fibrosis. In this study, we evaluated the upregulation of Duox1 and Duox2 pathways in hearts following chest irradiation in rats and then detected possible attenuation of them by melatonin. Materials and Methods: Twenty male Wistar rats were divided into four groups: (1) control; (2) melatonin treated (100 mg/kg); (3) radiation (15 Gy gamma rays); (4) melatonin treated before irradiation. All rats were sacrificed after 10 weeks and their heart tissues collected for real-time PCR (RT-PCR), ELISA detection of IL-4 and IL-13, as well as histopathological evaluation of macrophages and lymphocytes infiltration. Results: Results showed an upregulation of IL-4, IL4ra1, Duox1, and Duox2. The biggest changes were for IL4ra1 and Duox1. Treatment with melatonin before irradiation could attenuate the upregulation of all genes. Melatonin also caused a reduction in IL-4 as well as reverse infiltration of inflammatory cells. Conclusion: Duox1 and Duox2 may be involved in the late effects of radiation-induced heart injury. Also, via attenuation of these genes, melatonin can offer protection against the toxic effects of radiation on the heart. © 2019 by the authors