Altered expression of iron regulatory proteins with aging is associated with transient hepatic iron accumulation after environmental heat stress

Hepatic Macrophage Abundance and Phenotype in Aging and Liver Iron Accumulation

Liver macrophages serve important roles in iron homeostasis through phagocytosis of effete erythrocytes and the export of iron into the circulation. Conversely, intracellular iron can alter macrophage phenotype. Aging increases hepatic macrophage number and nonparenchymal iron, yet it is unknown whether age-related iron accumulation alters macrophage number or phenotype. To evaluate macrophages in a physiological model of iron loading that mimicked biological aging, young (6 mo) Fischer 344 rats were given one injection of iron dextran (15 mg/kg), and macrophage number and phenotype were evaluated via immunohistochemistry. A separate group of old (24 mo) rats was treated with 200 mg/kg deferoxamine every 12 h for 4 days. Iron administration to young rats resulted in iron concentrations that matched the values and pattern of tissue iron deposition observed in aged animals; however, iron did not alter macrophage number or phenotype. Aging resulted in significantly greater numbers of M1 (CD68⁺) and M2 (CD163⁺) macrophages in the liver, but neither macrophage number nor phenotype were affected by deferoxamine. Double-staining experiments demonstrated that both M1 (iNOS⁺) and M2 (CD163⁺) macrophages contained hemosiderin, suggesting that macrophages of both phenotypes stored iron. These results also suggest that age-related conditions other than iron excess are responsible for the accumulation of hepatic macrophages with aging.

Biomarkers of Senescence during Aging as Possible Warnings to Use Preventive Measures

Human life expectancy is increasing significantly over time thanks to the improved possibility for people to take care of themselves and the higher availability of food, drugs, hygiene, services, and assistance. The increase in the average age of the population worldwide is, however, becoming a real concern, since aging is associated with the rapid increase in chronic inflammatory pathologies and degenerative diseases, very frequently dependent on senescent phenomena that occur alongside with senescence. Therefore, the search for reliable biomarkers that can diagnose the possible onset or predict the risk of developing a disease associated with aging is a crucial target of current medicine. In this review, we construct a synopsis of the main addressable biomarkers to study the development of aging and the associated ailments.

L-Arginine alleviates the testosterone reduction in heat-treated mice by upregulating LH secretion, the testicular antioxidant system and expression of steroidogenesis-related genes

High temperature can reduce testes function, leading to decreased testosterone secretion. Dietary l-arginine (l-Arg) supplementation improves the semen quality and libido of boars. The present study investigated whether l-Arg could enhance the production of testosterone in mice exposed to high ambient temperature. Twenty-four 6-week-old male ICR mice were randomly divided into three groups: a control group, a heat-treated (HT) group and a group subjected to heat treatment plus 2mg kg-1 l-Arg (HT+Arg). l-Arg was administered to mice by oral gavage for 18 consecutive days, after which the HT and HT+Arg groups were placed into an incubator at 40°C for 30min every day for 5 days. Serum testosterone and LH concentrations were significantly increased in the HT+Arg compared with HT group, as was catalase, total superoxide dismutase and glutathione peroxidase activity and the expression of steroidogenesis-related genes steroidogenic acute regulatory protein (Star), steroidogenic factor-1 (Sf1), 17β-hydroxysteroid dehydrogenase 3 (Hsd17b3) and 17α-hydroxylase/17,20-lyase (Cyp17a1) in the testes. These results demonstrate that l-Arg can alleviate testosterone reductions in heat-treated mice by upregulating LH secretion, enhancing the antioxidant system and increasing the expression of testosterone synthesis-related genes.

Renal Iron Accumulation and Oxidative Injury With Aging: Effects of Treatment With an Iron Chelator

Dysregulation of iron metabolism in the kidney may contribute to age-related increases in renal oxidative stress and dysfunction. This study assessed the effects of short-term iron chelation on markers of iron status, oxidative stress, inflammation, and autophagy in the kidneys of old rats. Old Fischer 344 rats (24 months) were treated with deferoxamine (DFO; 200 mg/kg, twice daily for 4.5 days); saline-treated young (6 months) and old rats served as controls. Renal nonheme iron was significantly higher in the old rats, with iron localized in the renal cortex. Ferritin levels were elevated in the kidneys of old rats, while expression of several antioxidant enzymes and mitochondrial proteins were reduced and protein carbonyls increased compared to young rats. DFO treatment significantly reduced ferritin levels, and increased transferrin receptor-1 protein, but did not affect nonheme iron content or protein carbonyls, nor did it reverse age-related changes in antioxidant enzymes and mitochondrial proteins. Although short-term DFO treatment did not mitigate the age-related increase in iron content and oxidative damage, this work demonstrates that old rats respond appropriately to DFO, suggesting that optimization of iron chelation regimens could be useful in improving renal homeostasis with aging.

Testosterone propionate activated the Nrf2-ARE pathway in ageing rats and ameliorated the age-related changes in liver

The present study aimed to evaluate the protective efficacy of testosterone propionate (TP) on age-related liver changes via activation of the nuclear factor erythroid 2-related factor 2-antioxidant response element (Nrf2-ARE) pathway in aged rats. Aged rats received subcutaneous injections of TP (2 mg/kg/d, 84 days). Oxidative stress parameters and the expression levels of signal transducer and activator of transcription 5b (STAT5b), Kelch-like ECH associating protein-1 (Keap1), Nrf2, haem oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase-1 (NQO1) in liver tissues were examined to check whether the Nrf2-ARE pathway was involved in the age-related changes in liver. Our results showed that TP supplementation alleviated liver morphology, liver function and liver fibrosis; improved oxidative stress parameters; and increased the expression of STAT5b, Nrf2, HO-1 and NQO-1 and decreased the expression of Keap1 in the liver tissues of aged rats. These results suggested that TP increased the expression of STAT5b, and then activated the Nrf2-ARE pathway and promoted antioxidant mechanisms in aged rats. These findings may provide new therapeutic uses for TP in patients with age-related liver changes.

Serum, erythrocyte and urinary concentrations of iron, copper, selenium and zinc do not change during an incremental test to exhaustion in either normothermic or hyperthermic conditions

AIM

The aim of this study was to evaluate the effect of the performance of an incremental exercise test until exhaustion in normothermic and hyperthermic conditions on serum, erythrocyte and urine concentrations of Iron (Fe), Copper (Cu), Selenium (Se) and Zinc (Zn).

METHODS

Nineteen adult males (age: 22.58 ± 1.06 years) performed two maximum incremental exercise tests on a cycloergometer in normothermia (22 ± 2 °C) and hyperthermia (42±2 °C) separated by 48 h. Urine, serum and erythrocyte samples were collected before and after each test.

RESULTS

Serum Se (p < 0.01) and Cu (p < 0.05) levels were altered after each test, but the significance disappeared with the correction for haematocrit. The rest of the values did not undergo alterations in either condition.

CONCLUSIONS

It seems that a higher stimulus is necessary to obtain changes in these minerals. The study reveals the need to correct serum concentrations concerning possible changes in these volumes after an acute effort.

DMT1 Expression and Iron Levels at the Crossroads Between Aging and Neurodegeneration

Iron homeostasis is an essential prerequisite for metabolic and neurological functions throughout the healthy human life, with a dynamic interplay between intracellular and systemic iron metabolism. The development of different neurodegenerative diseases is associated with alterations of the intracellular transport of iron and heavy metals, principally mediated by Divalent Metal Transporter 1 (DMT1), responsible for Non-Transferrin Bound Iron transport (NTBI). In addition, DMT1 regulation and its compartmentalization in specific brain regions play important roles during aging. This review highlights the contribution of DMT1 to the physiological exchange and distribution of body iron and heavy metals during aging and neurodegenerative diseases. DMT1 also mediates the crosstalk between central nervous system and peripheral tissues, by systemic diffusion through the Blood Brain Barrier (BBB), with the involvement of peripheral iron homeostasis in association with inflammation. In conclusion, a survey about the role of DMT1 and iron will illustrate the complex panel of interrelationship with aging, neurodegeneration and neuroinflammation.

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.