The impact of erythropoietin and iron status on brain myelination in the newborn rat

Iron stores at birth in a full-term normal birth weight birth cohort with a low level of inflammation

Iron stores at birth are essential to meet iron needs during the first 4-6 months of life. The present study aimed to investigate iron stores in normal birth weight, healthy, term neonates. Umbilical cord blood samples were collected from apparently normal singleton vaginal deliveries (n=854). Subjects were screened and excluded if C-reactive protein (CRP) > 5 mg/l or α1-acid glycoprotein (AGP) > 1 g/l, preterm (<37 complete weeks), term < 2500g or term > 4000g. In total, 762 samples were included in the study. Serum ferritin, soluble transferrin receptor (sTfR), hepcidin, and erythropoietin (EPO) were measured in umbilical cord blood samples; total body iron (TBI) (mg/kg) was calculated using sTfR and ferritin concentrations. A total of 19.8% newborns were iron deficient (ferritin 35 μg/l) and an additional 46.6% had insufficient iron stores (ferritin < 76 μg/l). There was a positive association between serum ferritin and sTfR, hepcidin, and EPO. Gestational age was positively associated with ferritin, sTfR, EPO, and hepcidin. In conclusion, we demonstrate a high prevalence of insufficient iron stores in a Chinese birth cohort. The value of cord sTfR and TBI in the assessment of iron status in the newborn is questionable, and reference ranges need to be established.

Environmental and Nutritional "Stressors" and Oligodendrocyte Dysfunction: Role of Mitochondrial and Endoplasmatic Reticulum Impairment

Oligodendrocytes are myelinating cells of the central nervous system which are generated by progenitor oligodendrocytes as a result of maturation processes. The main function of mature oligodendrocytes is to produce myelin, a lipid-rich multi-lamellar membrane that wraps tightly around neuronal axons, insulating them and facilitating nerve conduction through saltatory propagation. The myelination process requires the consumption a large amount of energy and a high metabolic turnover. Mitochondria are essential organelles which regulate many cellular functions, including energy production through oxidative phosphorylation. Any mitochondrial dysfunction impacts cellular metabolism and negatively affects the health of the organism. If the functioning of the mitochondria is unbalanced, the myelination process is impaired. When myelination has finished, oligodendrocyte will have synthesized about 40% of the total lipids present in the brain. Since lipid synthesis occurs in the cellular endoplasmic reticulum, the dysfunction of this organelle can lead to partial or deficient myelination, triggering numerous neurodegenerative diseases. In this review, the induced malfunction of oligodendrocytes by harmful exogenous stimuli has been outlined. In particular, the effects of alcohol consumption and heavy metal intake are discussed. Furthermore, the response of the oligodendrocyte to excessive mitochondrial oxidative stress and to the altered regulation of the functioning of the endoplasmic reticulum will be explored.

How to Improve the Antioxidant Defense in Asphyxiated Newborns-Lessons from Animal Models

Oxygen free radicals have been implicated in brain damage after neonatal asphyxia. In the early phase of asphyxia/reoxygenation, changes in antioxidant enzyme activity play a pivotal role in switching on and off the cascade of events that can kill the neurons. Hypoxia/ischemia (H/I) forces the brain to activate endogenous mechanisms (e.g., antioxidant enzymes) to compensate for the lost or broken neural circuits. It is important to evaluate therapies to enhance the self-protective capacity of the brain. In animal models, decreased body temperature during neonatal asphyxia has been shown to increase cerebral antioxidant capacity. However, in preterm or severely asphyxiated newborns this therapy, rather than beneficial seems to be harmful. Thus, seeking new therapeutic approaches to prevent anoxia-induced complications is crucial. Pharmacotherapy with deferoxamine (DFO) is commonly recognized as a beneficial regimen for H/I insult. DFO, via iron chelation, reduces oxidative stress. It also assures an optimal antioxidant protection minimizing depletion of the antioxidant enzymes as well as low molecular antioxidants. In the present review, some aspects of recently acquired insight into the therapeutic effects of hypothermia and DFO in promoting neuronal survival after H/I are discussed.

Sevoflurane anesthesia during pregnancy in mice induces cognitive impairment in the offspring by causing iron deficiency and inhibiting myelinogenesis

Maternal anesthetic exposure during pregnancy is associated with an increased risk of cognitive impairment in offspring. The balance of cerebral iron metabolism is essential for the development of brain tissue. Iron deficiency affects the myelinogenesis and nerve tissue development, especially in fetus or infant, which has a key role in cognitive function. We aimed to investigate whether maternal sevoflurane (Sev) exposure caused cognitive impairment in offspring through inducing iron deficiency and inhibiting myelinogenesis. Pregnant mice (gestation stage day 14) were treated with 2% Sev for 6 h. Cognitive function of offspring mice was determined by the Morris water maze and Context fear conditioning test. Iron levels were assayed by Perl's iron staining and synchrotron imaging. Hippocampus and cortex tissues or cerebral microvascular endothelial cells of offspring mice (postnatal day 35) were harvested and subjected to Western blot and/or immunhistochemistry to assess ferritin, transferrin receptor 1(TfR1), Ferroportin-1 (FpN1), myelin basic protein (MBP), tight junction protein ZO-1, occludin, and claudin-5 levels. Beginning with postnatal day 30, the offspring were treated with iron therapy for 30 days, and the indicators above were tested. Our results showed Sev dramatically decreased the iron levels of brain and impaired cognitive function in offspring mice. Sev decreased the expression of heavy chain ferritin (FtH), light chain ferritin (FtL), MBP, ZO-1, occludin, claudin-5, and FpN1, and increased TfR1 in hippocampus and cortex or cerebral microvascular endothelial cells of offspring mice, indicating that Sev caused the iron deficiency and impaired the myelinogenesis in the brain of offspring. Interestingly, iron therapy prompted the myelinogenesis and improved impaired cognitive function at postnatal day 60. Our research uncovered a new mechanism which showed that iron deficiency induced by Sev and myelin formation disorder due to decreased iron of brain may be an important risk factor for cognitive impairment in offspring. It was necessary for offspring to be supplied iron supplement whose mother suffered exposure to sevoflurane during pregnancy.

Deferoxamine Alleviates Iron Overload and Brain Injury in a Rat Model of Brainstem Hemorrhage

BACKGROUND

Brainstem hemorrhage (BSH) is the most dangerous and devastating subtype of intracerebral hemorrhage and is associated with high morbidity and mortality. However, to date, no effective prevention methods or specific therapies have been available to improve its clinical outcomes. We preliminarily explored the efficacy of deferoxamine (DFO), a clinical chelator known for its iron-scavenging activities, in a rat model of BSH induced with collagenase infusion.

METHODS

DFO or saline was administrated 6 hours after BSH induction and then every 12 hours for ≤7 days. The survival curve of the rats was created, and the neurological scores were examined on days 1, 3, and 7 after BSH. The rats were sacrificed after 1, 3, and 7 days of DFO treatment for histological examination and immunohistochemistry.

RESULTS

The results showed that administration of DFO delayed erythrocytes lysis, reduced iron deposition, reduced reactive oxygen species generation, reduced heme oxygenase-1 expression, and alleviated brain injury such as neuron degeneration and myelin sheath injury. However, DFO did not improve the survival rate and neurobehavioral outcomes in this model.

CONCLUSIONS

Administration of DFO had limited therapeutic effects on collagenase-induced brainstem hemorrhage in rats. Some potential explanations were proposed, and more preclinical work is required to clarify the controversial curative effect of DFO in ICH.

Danggui Buxue Tang, an ancient Chinese herbal decoction, protects β-amyloid-induced cell death in cultured cortical neurons

Background

Danggui Buxue Tang (DBT) is a historical Chinese herbal decoction, and which has more than 800 years of applications. This herbal decoction solely contains two materials: Astragali Radix (AR) and Angelicae Sinensis Radix (ASR) at a weight ratio of 5:1. Clinically, DBT aims to improve anemia syndrome. In complementary and alternative medicine theory, the cause of neurodegenerative disease is proposed to be related with anemia. In line to this notion, low levels of hemoglobin and red blood cell have been reported in patients suffering from Alzheimer’s disease (AD), a chronic neurodegenerative disease caused by β-amyloid peptide (Aβ) accumulation. Therefore, we would like to probe the neuroprotective functions of this ancient herbal formula in vitro.

Method

The neuroprotective effects of DBT in the Aβ-induced cell death were detected in cultured cortical neurons by multiple techniques, i.e. confocal and western blot.

Results

In the cultures, application of DBT reduced Aβ-induced apoptosis rate in a dose-dependent manner. In Aβ-treated cortical neurons, the expression ratio of Bcl2 to Bax was altered by DBT. In parallel, application of DBT markedly suppressed the Aβ-induced expressions of apoptotic markers, i.e. cleaved-caspase 3/9 and PARP.

Conclusion

Taken these results, DBT shows promising protective effects against Aβ-induced stress or insult in cultured neurons.