Injury In Aged Rats Research Articles

Alleviating Acute Lung Injury Induced by Lipopolysaccharide: Dayuan Yin Suppresses Inflammation and Oxidative Stress in Elderly Male Rats.

The occurrence of acute lung injury (ALI) caused by lipopolysaccharide (LPS) is prevalent and perilous among older individuals. Inflammation and oxidative stress are vital factors in the progression of ALI in this population. Dayuan Yin (DYY) is a classic Chinese herbal formula used for treating pulmonary diseases. Therefore，this situation can be well simulated by selecting suitable aged rats and induced by LPS, which is helpful to evaluate the role of DYY. The objective of this study is to assess the therapeutic efficacy of DYY in reducing pulmonary inflammation and oxidative stress injury in aged rats induced by LPS. In elderly male Sprague Dawley (SD) rats, the ALI model was induced by injecting LPS into the peritoneal cavity. The therapeutic effect of the DYY group was evaluated after 3 days of oral administration. Lung tissue damage was assessed using hematoxylin-eosin staining and the lung wet/dry (W/D) ratio. Inflammatory reaction in lung tissue was analyzed by counting inflammatory agents, measuring total protein (TP), and examining the concentration of inflammatory components in bronchoalveolar lavage fluid (BALF). Lung oxidative stress was assessed by measuring malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), and superoxide dismutase (SOD) levels in BALF. The impact of DYY on the phosphorylation of PI3K, AKT, and NF-κBp65 protein was analyzed using Western Blot (WB). The administration of DYY exhibited a dose-dependent reduction in the severity of lung injury caused by LPS, leading to a reversal of the LPS-induced lung W/D ratio. Furthermore, DYY treatment resulted in decreased levels of leukocytes, eosinophils, neutrophils, macrophages, lymphocytes, and total protein in BALF. Additionally, DYY significantly inhibited the upregulation of Interleukin -6, Interleukin -10, and Interleukin -1β (IL-6, IL-10, IL-1β) as well as Tumor necrosis factor-α(TNF-α) induced by LPS (P<0.01). The lungs experienced oxidative stress due to LPS, leading to the production of MDA and iNOS, as well as a decrease in SOD activity. DYY reduced oxidative stress in the lungs and inhibited the activation of p-PI3K, p-Akt, and p-NF-κBp65, with a greater effect at higher doses. In a dose-dependent manner, DYY suppresses the inflammatory response and oxidative stress in the lung tissue of elderly rats, thereby reducing ALI caused by LPS. This effect may be attributed to the inhibition of the PI3K/AKT/NF-κB pathway activation.

Cardioprotective effect of naringin against the ischemia/reperfusion injury of aged rats.

Aging is known as a main risk factor in the development of cardiovascular diseases. Naringin (NRG) is a flavonoid compound derived from citrus fruits. It possesses a wide spectrum of pharmacological properties, including antioxidant anti-inflammatory, and cardioprotective. This investigation aimed to assess the cardioprotective effect of NRG against the ischemia/reperfusion (I/R) injury in aged rats. In this study, D-galactose (D-GAL) at the dose of 150 mg/kg/day for 8 weeks was used to induce aging in rats. Rats were orally gavaged with NRG (40 or 100 mg/kg/day), in co-treatment with D-GAL, for 8 weeks. The Langendorff isolated heart was used to evaluate the effect of NRG on I/R injury in aged rats. NRG treatment diminished myocardial hypertrophy and maximum contracture level in aged animals. During the pre-ischemic phase, reduced heart rate was normalized by NRG. The effects of D-GAL on the left ventricular end diastolic pressure (LVDP), the rate pressure product (RPP), and the minimum and maximum rate of left ventricular pressure (±dp/dt) improved by NRG treatment in the perfusion period. NRG also enhanced post-ischemic recovery of cardiac functional parameters (± dp/dt, and RPP) in isolated hearts. An increase in serum levels of the lactate dehydrogenase (LDH), the creatine kinase-MB (CK-MB), and the tumor necrosis factor-alpha (TNF-α) were reversed by NRG in aged rats. It also normalized the D-GAL-decreased the superoxide dismutase (SOD) activity in the heart tissue. NRG treatment alleviated cardiac injury in aged hearts under conditions of I/R. NRG may improve aging-induced cardiac dysfunction through anti-oxidative and anti-inflammatory mechanisms.

Mitoprotective effect of mesenchymal stem cells-derived conditioned medium in myocardial reperfusion injury of aged rats: role of SIRT-1/PGC-1α/NRF-2 network.

The aged myocardium experiences various forms of stress that cause reduction of its tolerance to injury induced by ischemia/reperfusion (I/R). Developing effective cardioprotective modalities to prevent the amplification of I/R injury during aging is under focus of investigation. Mesenchymal stem cells (MSCs) have the ability to regenerate infarcted myocardium mostly by producing multiple secretory factors. This study aimed to explore the mechanisms of mitoprotection by MSCs-conditioned medium (CM) in myocardial I/R injury of aged rats. Male Wistar rats (n = 72, 400-450g, 22-24months old) were randomized into groups with/without I/R and/or MSCs-CM treatment. To establish myocardial I/R injury, the method of LAD occlusion and re-opening was employed. MSCs-CM was administered intramyocardially (150μl) at the onset of reperfusion in recipient group. After 24h reperfusion, myocardial infarct size, LDH level, mitochondrial functional endpoints, expression of mitochondrial biogenesis-associated genes, and the levels of pro-inflammatory cytokines were evaluated. After 28days reperfusion, echocardiographic assessment of cardiac function was performed. MSCs-CM treatment improved myocardial function and decreased infarct size and LDH level in aged I/R rats (P < .05 to P < .001). It also decreased mitochondrial ROS formation, enhanced mitochondrial membrane potential and ATP content, upregulated mitochondrial biogenesis-related genes including SIRT-1, PGC-1α, and NRF-2, and lessened TNF-α, IL-1β, and IL-6 levels (P < .05 to P < .01). MSCs-CM treatment attenuated myocardial I/R injury in aged rats, in part by improving mitochondrial function and biogenesis and restraining inflammatory reaction. the upregulation of SIRT-1/PGC-1α/NRF-2 profiles is a possible target for the mitoprotective effects of MSCs-CM following I/R injury during aging.

Mitochondria-targeted combination treatment strategy counteracts myocardial reperfusion injury of aged rats by modulating autophagy and inflammatory response.

Aging, as a recognized risk factor for ischemic heart disease, interferes with protective mechanisms and abolishes the optimal effectiveness of cardioprotective interventions, leading to the loss of cardioprotection following myocardial ischemia/reperfusion (I/R) injury. This study was designed to explore the possible interaction of aging with cardioprotection induced by combination therapy with coenzyme Q10 (CoQ10) and mitochondrial transplantation in myocardial I/R injury of aged rats. Male Wistar rats (n = 72, 400-450g, 22-24 months old) were randomized into groups with/without I/R and/or CoQ10 and mitochondrial transplantation, alone or in a combinational mode. An in vivo model of myocardial I/R injury was established by left anterior descending coronary artery occlusion and re-opening. Mitochondria were isolated from donor rats and injected intramyocardially (150µl of the mitochondrial suspension containing 2 × 105±0.3 × 105 mitochondria) at the onset of reperfusion in recipient groups. CoQ10 (20mg/kg/day) was injected intramuscularly for 7 days before I/R operation. Lastly, myocardial function, cTn-I level, expression of autophagy-associated proteins (Beclin1, p62, and LC3-II/LC3-I), and the levels of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) were assessed. Co-application of CoQ10 and mitotherapy concomitantly improved myocardial function and decreased cTn-I level in aged reperfused hearts (P < .001). This combination therapy also modulated autophagic activity and decreased pro-inflammatory cytokines (P < .01 to P < .001). This combinational approach induced noticeable cardioprotection in comparison with monotherapies-received groups. We found that combination of CoQ10 and mitochondrial transplantation attenuated myocardial I/R injury in aged rats, in part by modulating autophagy and inflammatory response, hence, appears to restore aging-related loss of cardioprotection in aged patients.

The Protective Effect and Mechanism of Baicalin on Postoperative Cognitive Function and Nerves in Aged Rats

To explore the effect of baicalin on cognitive function and nerves after splenectomy in aged rats is the main objective of the study. Aged rats were randomly divided into a sham operation group, a model group (to construct a splenectomy surgical model) and a baicalin treatment group (baicalin was given after the model was constructed). The pathological conditions like interleukin-6, tumor necrosis factor alpha, interleukin-1 beta content; brain detection by terminal deoxynucleotidyl transferase dUTP nick end labeling method apoptosis of tissue cell; western blot method was used to detect the expression of related proteins and real-time fluorescence quantitative polymerase chain reaction method was used to detect the messenger ribonucleic acid levels of related genes. Compared with the control group, the brain tissue cell apoptosis increased and the expression of inflammatory factors increased in the model group; compared with the model group, the brain tissue apoptosis of the baicalin treatment group decreased, the expression of Ki67 positive cells increased and the inflammation-related factor interleukin-6, tumor necrosis factor alpha, interleukin-1 beta levels were significantly decreased, N-methyl D-aspartate receptor subtype 2B, phosphorylated-extracellular signal-regulated kinase, phosphorylated-cAMP response element-binding protein expressions were significantly increased. Baicalin can improve postoperative cognitive dysfunction and nerve injury in aged rats after splenectomy by improving the pathological state of brain tissue, attenuating the inflammatory response and promoting apoptosis of brain tissue.

Interaction of nitric oxide synthase and mitochondrial ATP-sensitive potassium channels in protective impacts of combination therapy with irisin-preconditioning and melatonin-postconditioning in myocardial ischemia/reperfusion in aging

ObjectivesThe main challenge for cardioprotection in patients with cardiac ischemia–reperfusion (I/R) damage is the existence of negatively-acting multiple risk factors such as aging. This work aimed to evaluate the efficacy of combined therapy with irisin and melatonin on cardiac I/R injury in aged rats by focusing on the involvement of mitochondrial ATP-sensitive potassium (mitoKATP) channels, and the eNOS/NO pathway. MethodsMale aged Wistar rats (78 rats, 400–450 g) were experienced LAD ligation for 30 min followed by 3 h or 2 weeks reperfusion. Irisin (0.5 mg/kg/day) was administered for one week before ischemic insult. Melatonin (20 mg/kg) was administered 10 min before the onset of reperfusion. The releases of CK and LDH, mitochondrial function, inflammatory and apoptosis responses, the expression of eNOS, the levels of NO, cardiac function, and infarct size (IS) were evaluated. ResultsCombined therapy with irisin and melatonin significantly improved heart function, reduced IS, and limited the releases of CK and LDH (P < 0.01 for all). This combined therapy improved mitochondrial function, decreased inflammatory cytokines and apoptosis response, and increased eNOS/NO activity (P < 0.05 for all). Monotherapies had no significant impacts. Inhibition of mitoKATP channels and eNOS enzyme by 5HD and L-NAME, respectively, reversed the cardioprotective effects of combination therapy (P < 0.05), however, the effect of 5HD was more potent as compared to L-NAME (P < 0.05). ConclusionsIt can be suggested that combined therapy with irisin and melatonin can be proposed as a potential candidate to mitigate the I/R severity of aged hearts via activation of mitoKATP channels partly through the eNOS/NO signaling pathway.

Pretreatment with nicotinamide mononucleotide increases the effect of ischaemic postconditioning on cardioprotection and mitochondrial function following ex vivo myocardial reperfusion injury in aged rats.

The present study aims to evaluate the combined effect of ischaemic postconditioning (IPostC) and nicotinamide mononucleotide (NMN) on cardioprotection and mitochondrial function in aged rats subjected to myocardial ischaemia-reperfusion (IR) injury. Sixty aged Wistar rats were randomly divided into fivegroups (n=12), including sham, control, NMN, IPostC, and NMN+IPostC. Regional ischaemia was induced by 30-min occlusion of the left anterior descending coronary artery (LAD) followed by 60-min reperfusion. IPostC was applied at the onset of reperfusion, by six cycles of 10-s reperfusion/ischaemia. NMN (100mg/kg) was intraperitoneally injected every other day for 28days before IR. Myocardial haemodynamics and infarct size (IS) were measured, and the left ventricles samples were harvested to assess cardiac mitochondrial function. The results showed that all treatments reduced lactate dehydrogenase release compared to those of the control group. IPostC alone failed to reduce IS and myocardial function. However, NMN and combined therapy could significantly improve myocardial function and decrease the IS compared to the control animals. Moreover, the effects of combined therapy on the decrease of IS, mitochondrial reactive oxygen species (ROS), and improvement of mitochondrial membrane potential (MMP) were greater than those of stand-alone treatments. These results demonstrated that cardioprotection by combined therapy with NMN+IPostC was superior to individual treatments, and pretreatment of aged rats with NMN was able to correct the failure of IPostC in protecting the hearts of aged rats against IR injury.

Modeling chronic cervical spinal cord injury in aged rats for cell therapy studies

With an expanding elderly population, an increasing number of older adults will experience spinal cord injury (SCI) and might be candidates for cell-based therapies, yet there is a paucity of research in this age group. The objective of the present study was to analyze how aged rats tolerate behavioral testing, surgical procedures, post-operative complications, intra-spinal cell transplantation and immunosuppression, and to examine the effectiveness of human iPSC-derived Neural Progenitor Cells (IMR90-hiPSC-NPCs) in a model of SCI. We performed behavioral tests in rats before and after inducing cervical hemi-contusions at C4 level with a fourth-generation Ohio State University Injury Device. Four weeks later, we injected IMR90-hiPSC-NPCs in animals that were immunosuppressed by daily cyclosporine injection. Four weeks after injection we analyzed locomotor behavior and mortality, and histologically assessed the survival of transplanted human NPCs. As rats aged, their success at completing behavioral tests decreased. In addition, we observed high mortality rates during behavioral training (41.2%), after cervical injury (63.2%) and after cell injection (50%). Histological analysis revealed that injected cells survived and remained at and around the grafted site and did not cause tumors. No locomotor improvement was observed in animals four weeks after IMR90-hiPSC-NPC transplantation. Our results show that elderly rats are highly vulnerable to interventions, and thus large groups of animals must be initially established to study the potential efficacy of cell-based therapies in age-related chronic myelopathies.

Hydrogen Sulfide Prevents Mesenteric Adipose Tissue Damage, Endothelial Dysfunction, and Redox Imbalance From High Fructose Diet-Induced Injury in Aged Rats.

A high fructose diet (HFD) and advanced age are key factors for the gradual loss of physiological integrity of adipose tissue. Endogenous hydrogen sulfide (H2S) has beneficial effects on cytoprotection and redox balance. But its interactive effects on age-related damage of mesenteric vessels and connective and adipose tissues (MA) during HFD which could be the base of the development of effective physiological-based therapeutic strategy are unknown. The aim of study was to investigate age- and HFD-induced mesenteric cellular changes and activities of enzymes in H2S synthesis and to test the effects of sodium hydrosulfide (NaHS) which is considered an H2S donor on them. Adult and aged male rats on a standard diet (SD) or 4-week HFD were exposed to acute water-immersion restraint stress (WIRS) for evaluation of mesenteric subcellular and cellular adaptive responses by electron microscopy. The effects of exogenous NaHS (5.6 mg/kg/day for 9 days) versus vehicle on mesentery changes were investigated. Serum glucose level, thiobarbituric acid reactive substances (TBARS), and activities of cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS), thiosulfate-dithiol sulfurtransferase (TST), and sulfite oxidase (SO) were examined by spectrophotometry. In both adult and aged SD groups, treatment with NaHS protected mesenteric cells after WIRS. In both groups, the treatment with NaHS also protected MA mitochondria, microvascular endothelial and sub-endothelial structures, and fibroblasts versus the vehicle-treated group that had signs of damage. HFD increased MA injury and mitochondrial changes in both aged and adult rats. HFD-associated malfunction is characterized by low activities of CSE, CBS, TST, SO, and increased TBARS. Finally, we demonstrated that pretreatment with NaHS inhibited MA and mitochondria alterations in aged rats exposed to HFD and WIRS, lowered TBARS, and enhanced H2S enzyme activities in contrast to the vehicle-treated group. Mitochondrial integrity alterations, endothelial damage, and redox imbalance are key factors for rat mesenteric adipose tissue damage during advanced age. These alterations and MA hypertrophic changes retain the central for HFD-induced damage. Moreover, H2S signaling contributes to MA and mitochondria redox balance that is crucial for advanced age and HFD injury. The future study of H2S donors’ effects on mesenteric cells is fundamental to define novel therapeutic strategies against metabolic changes.

Complement Inhibition Attenuates Early Erythrolysis in the Hematoma and Brain Injury in Aged Rats.

Background and Purpose- Early erythrolysis in the hematoma contributes to brain injury after intracerebral hemorrhage (ICH). This study investigated the effects of N-acetylheparin, a complement inhibitor, and aurin tricarboxylic acid, a membrane attack complex inhibitor, on early erythrolysis, brain iron deposition, and brain injury in aged rats. Methods- There were 3 parts in the study. First, aged (18 months old) male Fischer 344 rats had an ICH. The time course of erythrolysis in the hematoma was determined by T2* weighted magnetic resonance imaging, and the expression of CD163 was examined. Second, aged rats had an ICH with N-acetylheparin or vehicle. Rats were euthanized at days 1, 3, and 28 after magnetic resonance imaging (T2-, T2*-weighted, and T2* array) and behavioral tests. Brains were used for immunohistochemistry. Third, aged rats had an ICH with avaurin tricarboxylic acid or vehicle. The rats had magnetic resonance imaging and behavioral tests and were euthanized at day 3. Brains were used for immunohistochemistry. Results- Early erythrolysis occurred within the clot in aged F344 rats. There were increased numbers of CD163-positive cells after ICH. Almost all perihematomal CD163-positive cells were microglia/macrophages, while positive neurons were found more distant from the hematoma. Coinjection of N-acetylheparin attenuated erythrolysis, iron accumulation, CD163 expression, microglia activation, brain swelling, and neuronal death in the acute phase, as well as reducing brain atrophy and neurological deficits in the chronic phase. Coinjection of aurin tricarboxylic acid also reduced erythrolysis and ICH-induced brain injury. Conclusions- Inhibiting complement activation resulted in less erythrolysis and brain injury after ICH.

The adaptogenic anti-ageing potential of resveratrol against heat stress-mediated liver injury in aged rats: Role of HSP70 and NF-kB signalling.

Heat stress (HS) is a major international problem which has attracted a considerable attention due to its oxidative tissue effects and high morbidity and mortality rates, especially among elderly people. Discovering an effective antioxidant is pivotal for overcoming HS-induced injury. Therefore, the aim of this study was to estimate the hepatic protective effects of orally supplemented resveratrol (RES) against HS-mediated liver injury in young and old male Wistar albino rats. Compared to control rats, RES administered orally at a dose of 20 mg/kg BW for 21 successive days efficiently ameliorated HS-induced oxidative damage by significantly increasing (P ≤ 0.05) the level of reduced glutathione and glutathione peroxidase, and decreasing the levels of malondialdehyde and TNF-α in hepatic tissue of both young and aged rats. However, level of NF-κB was downregulated significantly in aged rats rather than young rats. Moreover, RES significantly decreased (P ≤ 0.05) the serum levels of aspartate transaminase and alkaline phosphatase in both ages of rats compared to their corresponding HS-stressed rats. Furthermore, RES upregulated the immunohistochemical expression of caspase 3 and heat shock protein 70 in young and aged rats, however it was more pronounced in young one. In addition, RES administration moderately normalized (P ≤ 0.0001) the harmful effects of HS on the hepatic architecture of both young and aged rats. In conclusion, this study reveals for the first time that RES exerts promising hepato-ameliorative effects against HS-induced oxidative stress in the young and aged rats via its antioxidant, anti-inflammatory, and anti-apoptotic effect, as well as via its inhibitory effect against the NF-κB signalling in a cellular system.

Paradoxical effect of testosterone supplementation therapy on cardiac ischemia/reperfusion injury in aged rats

Aging is followed by numerous physiological limitations that reduce health span, particularly cardiovascular and metabolic disorders. Testosterone supplementation therapy (TST) has been widely used in the treatment of aging dysfunctions in either adult or aged patients, although recent evidence have suggested that the incidence of myocardial infarction might be increased in elderly patients. So far, though, the effects of TST in the progression of cardiac ischemia/reperfusion (IR) injury in aged hearts remain unclear. Male aged (23–24 months old) and adult (6 months old) Wistar rats were treated with placebo (Old + Placebo n = 5 / Adult + Placebo n = 5) or TST (Old + TST n = 7 / Adult + TST n = 5) for 30 days. After euthanasia, artificially-perfused isolated rat hearts were submitted to IR. Cardiac expression levels of genes encoding α and β myosin heavy chain (MHC), ryanodine receptor (RyR), brain-natriuretic peptide (BNP), sarcoplasmic reticulum Ca2+ ATPase 2a (SERCA2a), glucose-regulated protein 78 kDa (GRP78), eukaryotic initiation factor 2α (eIF2α), C/EBP-homologous protein (CHOP), caspase 3 and B cell lymphoma 2 (Bcl-2) were accessed by qRT-PCR. Protein levels of CHOP, p-Akt, and p-glycogen synthase kinase 3β (p-GSK-3β) were measured by Western Blot. Compared to placebo-treated aged rats, Old + TST group exhibited increased heart weight and up-regulation of αMHC mRNA expression levels, whereas βMHC mRNA expression (p < 0.05). During reperfusion, left ventricular developed pressure, dP/dt+, dP/dt-, and cardiac contractile function index were increased in Old + TST rat hearts (p < 0.05), whereas infarct size was increased (p < 0.05) in comparison with Old + Placebo group. p-Akt levels of Old + TST rat hearts were decreased when compared to Old + Placebo group. Conversely, TST did not promote significant effects in adult rat hearts. Taken together, these findings suggest that myocardial stunning and infarct size of aged hearts were distinctly affected by TST.

Roflumilast promotes memory recovery and attenuates white matter injury in aged rats subjected to chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) has been associated with aging-related vascular dementia, including Alzheimer's disease. It can be induced by the four-vessel occlusion/internal carotid artery (4VO/ICA) model in aged rats, resulting in persistent memory deficits, white matter injury, and significant neuronal loss in the hippocampus and cerebral cortex. The phosphodiesterase type 4 inhibitor (PDE4-I) roflumilast has been reported to have pro-cognitive effects in several behavioral paradigms. The present study evaluated the effects of repeated roflumilast treatment in aged rats that were subjected to CCH. After surgery, roflumilast (0.003 and 0.01 mg/kg) was administered intraperitoneally once per day for 29 days. Memory performance was assessed in the aversive radial maze (AvRM) 7, 14, and 21 days after CCH. The effects of roflumilast on hippocampal neurodegeneration and white matter injury were investigated using Nissl and Kluver-Barrera staining, respectively. Western blot and RT-qPCR were used to explore microglial polarization using M1 (Iba-1 and iNOS) and M2 (Arginase-1) markers. Chronic cerebral hypoperfusion caused persistent memory deficits, hippocampal neurodegeneration, and vacuolization and fiber disarrangement in white matter. Repeated roflumilast treatment restored CCH-induced cognitive impairments in aged rats but in the absence of the rescue of hippocampal neurons. Attenuation of white matter injury was detected in the optic tract in aged CCH rats that were treated with roflumilast. In vitro, roflumilast increased Arg-1 gene expression in myelin-laden primary microglia. The present data suggest that roflumilast might be useful for the treatment of cognitive sequelae associated with CCH.

Role of Nrf2/ARE signaling pathway in propofol-induced reduction of lung ischemia-reperfusion injury in aged rats

Objective To evaluate the role of nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway in propofol-induced reduction of lung ischemia-reperfusion (I/R) injury in aged rats. Methods Thirty-two clean healthy male Sprague-Dawley rats, aged 18-22 months, weighing 450-600, were divided into 4 groups (n=8 each) using a random number table: sham operation group (group S), I/R group (group I/R), I/R plus propofol group (group I/R+ P) and all-trans retinoic acid (ARTA) plus I/R plus propofol group (group ARTA+ I/R+ P). Lung I/R was induced by occlusion of the right hilum of lung for 60 min followed by 120 min of reperfusion in anesthetized rats.In group ATRA+ I/R+ P, Nrf2/ARE signaling pathway blocker ARTA 6 mg/kg was intraperitoneally injected once a day for 3 consecutive days, and the model of lung I/R injury was established at 2 h after the last administration.In group I/R+ P and group ARTA+ I/R+ P, while the model of lung I/R injury was established, propofol 30 mg·kg-1·h-1 was infused via the caudal vein until 120 min of reperfusion.The rats were sacrificed at 120 min of reperfusion and then the lungs were removed for examination of the pathological changes which were scored and for measurement of wet/dry weight ratio (W/D ratio), superoxide dismutase (SOD) activity (by xanthine oxidase method), malondialdehyde (MDA) content (using thiobarbituric acid method) and expression of Nrf2 and heme oxygenase-l (HO-1) protein (by Western blot). Results Compared with group S, the pathological scores, W/D ratio and MDA content were significantly increased, and the activity of SOD was decreased in I/R and ATRA+ I/R+ P groups, and the expression of Nrf-2 and HO-1 was significantly up-regulated in I/R, I/R+ P and ATRA+ I/R+ P groups (P 0.05). Compared with group I/R+ P, the pathological scores, W/D ratio and MDA content were significantly increased, the activity of SOD was decreased, and the expression of Nrf-2 and HO-1 was down-regulated in group ARTA+ I/R+ P (P<0.05). Conclusion Nrf2/ARE signaling pathway activation is involved in propofol-induced reduction of lung I/R injury in aged rats. Key words: Propofol; Lung; Reperfusion injury; Nuclear factor-E2 related factor 2; Response elements

Minocycline Effects on Intracerebral Hemorrhage-Induced Iron Overload in Aged Rats

Brain iron overload is a key factor causing brain injury after intracerebral hemorrhage (ICH). This study quantified brain iron levels after ICH with magnetic resonance imaging R2* mapping. The effect of minocycline on iron overload and ICH-induced brain injury in aged rats was also determined. Aged (18 months old) male Fischer 344 rats had an intracerebral injection of autologous blood or saline, and brain iron levels were measured by magnetic resonance imaging R2* mapping. Some ICH rats were treated with minocycline or vehicle. The rats were euthanized at days 7 and 28 after ICH, and brains were used for immunohistochemistry and Western blot analyses. Magnetic resonance imaging (T2-weighted, T2* gradient-echo, and R2* mapping) sequences were performed at different time points. ICH-induced brain iron overload in the perihematomal area could be quantified by R2* mapping. Minocycline treatment reduced brain iron accumulation, T2* lesion volume, iron-handling protein upregulation, neuronal cell death, and neurological deficits (P<0.05). Magnetic resonance imaging R2* mapping is a reliable and noninvasive method, which can quantitatively measure brain iron levels after ICH. Minocycline reduced ICH-related perihematomal iron accumulation and brain injury in aged rats.

EFFECT OF ISCHEMIC PRECONDITIONING ON LIVER ISCHEMIA REPERFUSION INJURY IN AGED RATS

Background: As the criteria for liver donation have been extended to include marginal donors, liver grafts are becoming particularly vulnerable to hepatic ischemia-reperfusion injury (IRI). However, no specific measures have been validated to ameliorate hepatic IRI. Objective: To investigate the effect of ischemic preconditioning on hepatic ischemia/reperfusion (IR) injury in aged rats. Materials and Methods: The present study was performed on 45 aged male Wistar rats, weighing at the start of the study between 350-550 g. Animals were randomly divided into the following equal groups: Group I (Sham-operated control group), Group II (Liver ischemia reperfusion group): Rats were subjected to 1-hour partial liver ischemia followed by 24-hour reperfusion and Group III (ischemic preconditioned group): Rats were subjected to brief period of ischemia and reperfusion, then were subjected to hepatic IR as group II. Blood samples were collected and were subjected to measurement of Liver function tests, i.e. serum ALT, AST, liver malondialdehyde and glutathione peroxidase. Also, histopathological study of rat livers was performed. Results: There were significant decrease in liver weight and liver weight to body weight percent in IR group compared to the sham-operated rats. Upon preconditioning before IR, the liver weights still decreased compared to the sham-operated rats. Liver weight to body weight ratio ameliorated or less decreased in the ratio compared to sham-operated, and significantly increased in the ratio compared to the IR rats. There were significant increases in serum levels of liver enzymes (ALT and AST), at two time points, especially 24 hours after reperfusion as well as significant increase in hepatic MDA level in IR rats. In addition, IR has induced marked liver damage as shown by histopathological examination. Ischemic preconditioning ameliorated liver ischemia reperfusion injury as indicated by marked reduction in the liver enzymes although their levels did not match the levels recorded in the sham-operated rats and hepatic MDA. Hepatic level of GPx showed a significant increase compared to both the sham-operated and IR rats and that was associated with significant improvement of the histopathological examination compared to IR rats. Conclusion: Ischemic preconditioning ameliorated the hepatic injury associated with ischemia reperfusion. However, future work is needed to explain the mechanism by which IPC ameliorate liver IRI.

EFFECT OF ISCHEMIC PRECONDITIONING ON LIVER ISCHEMIA REPERFUSION INJURY IN AGED RATS

Background: As the criteria for liver donation have been extended to include marginal donors, liver grafts are becoming particularly vulnerable to hepatic ischemia-reperfusion injury (IRI). However, no specific measures have been validated to ameliorate hepatic IRI. Objective: To investigate the effect of ischemic preconditioning on hepatic ischemia/reperfusion (IR) injury in aged rats. Materials and Methods: The present study was performed on 45 aged male Wistar rats, weighing at the start of the study between 350-550 g. Animals were randomly divided into the following equal groups: Group I (Sham-operated control group), Group II (Liver ischemia reperfusion group): Rats were subjected to 1-hour partial liver ischemia followed by 24-hour reperfusion and Group III (ischemic preconditioned group): Rats were subjected to brief period of ischemia and reperfusion, then were subjected to hepatic IR as group II. Blood samples were collected and were subjected to measurement of Liver function tests, i.e. serum ALT, AST, liver malondialdehyde and glutathione peroxidase. Also, histopathological study of rat livers was performed. Results: There were significant decrease in liver weight and liver weight to body weight percent in IR group compared to the sham-operated rats. Upon preconditioning before IR, the liver weights still decreased compared to the sham-operated rats. Liver weight to body weight ratio ameliorated or less decreased in the ratio compared to sham-operated, and significantly increased in the ratio compared to the IR rats. There were significant increases in serum levels of liver enzymes (ALT and AST), at two time points, especially 24 hours after reperfusion as well as significant increase in hepatic MDA level in IR rats. In addition, IR has induced marked liver damage as shown by histopathological examination. Ischemic preconditioning ameliorated liver ischemia reperfusion injury as indicated by marked reduction in the liver enzymes although their levels did not match the levels recorded in the sham-operated rats and hepatic MDA. Hepatic level of GPx showed a significant increase compared to both the sham-operated and IR rats and that was associated with significant improvement of the histopathological examination compared to IR rats. Conclusion: Ischemic preconditioning ameliorated the hepatic injury associated with ischemia reperfusion. However, future work is needed to explain the mechanism by which IPC ameliorate liver IRI.

Effect of PUN282987 on global cerebral ischemia-reperfusion injury in aged rats

Objective To evaluate the effect of PUN282987 on global cerebral ischemia-reperfusion (I/R) injury in aged rats. Methods One hundred and twenty pathogen-free healthy male Sprague-Dawley rats, aged 18-22 months, weighing 450-600 g, were divided into 3 groups (n=40 each) using a random number table: sham operation group (group S), global cerebral I/R group (group I/R) and α7 nicotinic acetylcholine receptor (α7nAChR) agonist PNU282987 group (group PUN). The animals were anesthetized with intraperitoneal 10% chloral hydrate 0.4 ml/100g, and global cerebral I/R was produced by 4-vessel occlusion technique in I/R and PUN groups.PUN282987 2.4 mg/kg was injected intraperitoneally before ischemia in group PUN.At 1, 5, 12 and 24 h of reperfusion, 10 rats were randomly selected in each group and then sacrificed, and the brains were removed for detection of the neuronal apoptosis and for determination of the expression of α7nAChR, choline acetyltransferase (ChAT), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the hippocampal CA1 region.Apoptosis rate was calculated. Results Compared with group S, the apoptosis rate was significantly increased, and the expression of α7nAChR, ChAT, TNF-α and IL-1β was up-regulated at each time point in I/R and PUN groups (P<0.05). Compared with group I/R, the apoptosis rate was significantly decreased, the expression of α7nAChR and ChAT was up-regulated, and the expression of TNF-α and IL-1β was down-regulated at each time point in group PUN (P<0.05). Conclusion PUN282987 can reduce global cerebral I/R injury in aged rats. Key words: Reperfusion injury; Brain; Cholinergic agonists; Aged

An attenuated immune response by Schwann cells and macrophages inhibits nerve regeneration in aged rats

Although peripheral nerves are capable of regeneration, advanced age decreases the potential for functional recovery after injury. The cellular mechanisms for this are not currently understood. Here, we performed sciatic nerve grafting with young (2 months old) and aged (18 months old) Brown-Norway male rats, in which 1 cm nerve grafts from young or aged rats were sutured into nerves of young or aged rats. Axons were allowed to regenerate until the nerve grafts and distal nerves were harvested at 1, 3, and 7 days and 2 and 6 weeks. At 6 weeks, our data suggested that young nerve grafts supported regeneration better than aged nerve grafts. In addition, myelin debris clearance was inhibited in young nerves when grafted into aged rats, but clearance was faster when aged nerves were grafted into young rats. Further analysis revealed that aged macrophages have delayed migration into injured nerve, and macrophages and Schwann cells from aged rats were less phagocytic for myelin debris in vitro. To understand these impairments, expression levels of pro- and anti-inflammatory cytokines were analyzed at 1 day after injury. Based on these levels, there was not a clear polarization to either an M1 or M2 phenotype; however, expression levels of IL-6, IL-10, CCL2 (MCP1), and Arg-1 were decreased in aged nerves. Taken together, both macrophages and Schwann cells had attenuated responses to nerve injury in aged rats, leading to inefficient clearance of debris and impaired axonal regeneration.

Effect of fetal hypothyroidism on tolerance to ischemia–reperfusion injury in aged male rats: Role of nitric oxide

Aging is associated with increased prevalence of cardiovascular disease. Thyroid hormone deficiency during fetal life decreases myocardial tolerance to ischemia-reperfusion (IR) injury in later life. The long-term effects of fetal hypothyroidism (FH) on response to IR injury in aged rats have not been well documented. The aim of this study was therefore to compare the effect of FH on tolerance to IR injury in young and aged male rats and to determine contribution of iNOS (inducible nitric oxide synthase), Bax, and Bcl-2. Pregnant female rats were divided into two groups: The FH group received water containing 0.025% 6-propyl-2-thiouracil during gestation and the controls consumed tap water. Isolated perfused hearts from young (3 months) and aged (12 months) rats were subjected to IR. Hemodynamic parameters, infarct size, and heart NOx (nitrite+nitrate) levels were measured; in addition, mRNA expression of iNOS, Bax, and Bcl-2 and their protein levels in heart were measured. Recovery of post-ischemic LVDP and ±dp/dt were lower and infarct sizes were higher than controls in aged FH rats (68.38 ± 6.7% vs. 50.5 ± 1.7%; P < 0.05). Aged FH rats had higher heart NOx values than controls (74.3 ± 2.6 vs. 47.6 ± 2.5 μmol/L, P < 0.05). After IR, in FH rats, mRNA expression of iNOS and Bax were higher and Bcl-2 was lower in both the young (350 and 240% for iNOS and Bax, respectively and 51% for Bcl-2) and aged rats (504 and 567% for iNOS and Bax, respectively and 67% for Bcl-2). Compared to controls, in FH rats protein levels of iNOS (37% for young and 45% for aged rats) and Bax (94% for young and 118% for aged rats) were higher while for Bcl-2 (36% for young and 62% for aged rats) were lower. After IR, in FH rats, aminoguanidine, a selective iNOS inhibitor, decreased mRNA expression of iNOS and Bax and increased expression of Bcl-2 in both young (65% and 58% for iNOS and Bax, respectively and 152% for Bcl-2) and aged rats (76% and 64% for iNOS and Bax, respectively and 222% for Bcl-2). In addition, in the heart of FH rats, aminoguanidine decreased protein levels of iNOS (47% for young and 60% for aged rats) and Bax (57% for young and 80% for aged rats) and increased protein levels of Bcl-2 (124% for young and 180% for aged rats). In conclusion, thyroid hormone deficiency during fetal life decreases tolerance to IR injury in aged rats; this effect is at least in part, due to increased expression of iNOS and Bax-to-Bcl-2 ratio in the heart and is restored by iNOS inhibition.