Mitochondrial and Oxidative Stress Aspects in Hippocampus of Rats Submitted to Dietary n-3 Polyunsaturated Fatty Acid Deficiency After Exposure to Early Stress

Effects of early-life stress on peripheral and central mitochondria in male mice across ages

Exposure to early-life stress (ES) increases the vulnerability to develop metabolic diseases as well as cognitive dysfunction, but the specific biological underpinning of the ES-induced programming is unknown. Metabolic and cognitive disorders are often comorbid, suggesting possible converging underlying pathways. Mitochondrial dysfunction is implicated in both metabolic diseases and cognitive dysfunction and chronic stress impairs mitochondrial functioning. However, if and how mitochondria are impacted by ES and whether they are implicated in the ES-induced programming remains to be determined. ES was applied by providing mice with limited nesting and bedding material from postnatal day (P)2-P9, and metabolic parameters, cognitive functions and multiple aspects of mitochondria biology (i.e. mitochondrial electron transport chain (ETC) complex activity, mitochondrial DNA copy number, expression of genes relevant for mitochondrial function, and the antioxidant capacity) were studied in muscle, hypothalamus and hippocampus at P9 and late adulthood (10-12 months of age). We show that ES altered bodyweight (gain), adiposity and glucose levels at P9, but not in late adulthood. At this age, however, ES exposure led to cognitive impairments. ES affected peripheral and central mitochondria in an age-dependent manner. At P9, both muscle and hypothalamic ETC activity were affected by ES, while in hippocampus, ES altered the expression of genes involved in fission and antioxidant defence. In adulthood, alterations in ETC complex activity were observed in the hypothalamus specifically, whereas in muscle and hippocampus ES affected the expression of genes involved in mitophagy and fission, respectively. Our study demonstrates that ES affects peripheral and central mitochondria biology throughout life, thereby uncovering a converging mechanism that might contribute to the ES-induced vulnerability for both metabolic diseases and cognitive dysfunction, which could serve as a novel target for intervention.

N-3 PUFA-Deficiency in Early Life Exhibits Aggravated MPTP-Induced Neurotoxicity in Old Age while Supplementation with DHA/EPA-Enriched Phospholipids Exerts a Neuroprotective Effect

INTRODUCTION

Malnutrition in early life affects the growth and development of fetus and children, which has a long-term impact on adult health. Previous studies reveal a relationship between dietary omega-3 polyunsaturated fatty acid (n-3 PUFA) content, brain development, and the prevalence of neurodevelopmental disorders and inflammation. However, it is unclear about the effect of n-3 PUFA-deficiency in early life on the development of Parkinson's disease (PD) in old age, as well as the neuroprotective effect of DHA- and EPA-enriched phospholipids (DHA/EPA-PLs) supplemented in old age in long-term n-3 PUFA-deficient mice.

METHODS AND RESULTS

The PD mice induced by 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) in n-3 PUFA-adequate (N) and -deficient (DEF) group are supplemented with a DHA/EPA-PLs diet for 2 weeks (N+DPL, DEF+DPL). DHA/EPA-PLs supplementation significantly protects against MPTP-induced impairments. The DEF+DPL group shows poorer motor performance, the loss of dopaminergic neurons, mitochondrial dysfunction, and neurodevelopment delay than the N+DPL group, and still did not recover to the Control level.

CONCLUSIONS

Dietary n-3 PUFA-deficiency in early life exhibits more aggravated MPTP-induced neurotoxicity in old age, than DHA/EPA-PLs supplementation recovers brain DHA levels and exerts neuroprotective effects in old age in long-term n-3 PUFA-deficient mice, which might provide a potential dietary guidance.

Neonatal handling increases neurogenesis, BDNF and GR in the hippocampus favoring memory acquisition in rats

Early life is a critical period for the development of the central nervous system (CNS) when the brain undergoes functional organization, neuronal proliferation and migration. This study aimed to evaluate influences and possible interactions of the neonatal handling (NH) on morphologic, biochemical and molecular markers in the hippocampus, as well as on Mu opioid receptors (MOR) immunoreactivity when adolescent rats were exposed to morphine. On postnatal day (PND) 1, male pups were assigned to two experimental groups: unhandled (UH) or neonatal handling (NH), whose procedure was applied from PND2 to PND9. On PND 50, animals were submitted to memory behavioral test, anesthesia and euthanasia for blood collection and hippocampus removal. Animals exposed to NH showed: i) increased levels of proBDNF and brain-derived neurotrophic factor (BDNF); ii) increased memory performance; iii) decreased lipid peroxidation (LP) in plasma and hippocampus; iv) increased antioxidant defenses; v) increased glucocorticoids receptor (GR) levels. Interestingly, our data showed a positive correlation between BDNF and working memory after NH procedure (r² = 0.73; P = 0.006). Animals submitted to NH showed an increased per se of MOR immunoreactivity regardless of morphine exposure, while this increasing was also observed in the UH group after morphine exposure, even in a small extent. NH beneficial influence during early stage of life can be reflected during the development of the puppies, enhancing memory performance, preventing oxidative events and improving molecular targets in hippocampus. Further experimental studies in addition to clinical ones are needed to validate NH protocol as a therapeutic tool.

The Mitochondrion as Potential Interface in Early-Life Stress Brain Programming

Mitochondria play a central role in cellular energy-generating processes and are master regulators of cell life. They provide the energy necessary to reinstate and sustain homeostasis in response to stress, and to launch energy intensive adaptation programs to ensure an organism’s survival and future well-being. By this means, mitochondria are particularly apt to mediate brain programming by early-life stress (ELS) and to serve at the same time as subcellular substrate in the programming process. With a focus on mitochondria’s integrated role in metabolism, steroidogenesis and oxidative stress, we review current findings on altered mitochondrial function in the brain, the placenta and peripheral blood cells following ELS-dependent programming in rodents and recent insights from humans exposed to early life adversity (ELA). Concluding, we propose a role of the mitochondrion as subcellular intersection point connecting ELS, brain programming and mental well-being, and a role as a potential site for therapeutic interventions in individuals exposed to severe ELS.

Randomized trial of omega-3 for autism spectrum disorders: Effect on cell membrane composition and behavior

A high ω6/ω3 ratio [fatty acid (FA) index] in the cell membrane has been associated with inadequate brain development. It has started to be used as a biomarker of treatment efficacy in human diseases. The aim of this study was to investigate if omega-3 supplementation improves erythrocyte membrane ω6/ω3, plasma antioxidant status (TAS) and autistic behaviors. A randomized, crossover, placebo-controlled study was designed to investigate the effect of 8 weeks of supplementation with ω3 (962mg/d and 1155mg/d for children and adolescents, respectively). Sixty-eight children and adolescents with Autism Spectrum Disorders (ASD) completed the full protocol. Primary outcome measures were erythrocyte membrane FA composition and TAS. Secondary outcome measures were Social Responsiveness Scale and Clinical Global Impression-Severity. Treatment with ω3 improved the erythrocyte membrane ω6/ω3 ratio (treatment effect p<0.008, d=0.66; within subjects effect p<0.007, d=0.5) without changing TAS. There was a within subjects significant improvement in Social Motivation and Social Communication subscales scores, with a moderate to large effect size (p=0.004, d=0.73 and p=0.025, d=0.79 respectively), but no treatment effect (treatment-placebo order). Carryover effects cannot be discarded as responsible for the results in behavioral measures. In conclusion, supplementation with ω3 FA might be studied as an add-on to behavioral therapies in ASD. Optimal duration of treatment requires further investigation. With regard to side effects, the effect of this supplementation on the lipid profile needs monitoring.

Bezafibrate prevents mitochondrial dysfunction, antioxidant system disturbance, glial reactivity and neuronal damage induced by sulfite administration in striatum of rats: Implications for a possible therapeutic strategy for sulfite oxidase deficiency

Sulfite accumulates in tissues of patients affected by sulfite oxidase (SO) deficiency, a neurometabolic disease characterized by seizures and progressive encephalopathy, often resulting in early death. We investigated the effects of sulfite on mitochondrial function, antioxidant system, glial reactivity and neuronal damage in rat striatum, as well as the potential protective effects of bezafibrate on sulfite-induced toxicity. Thirty-day-old rats were intrastriatally administered with sulfite (2μmol) or NaCl (2μmol; control) and euthanized 30min after injection for evaluation of biochemical parameters and western blotting, or 7days after injection for analysis of glial reactivity and neuronal damage. Treatment with bezafibrate (30 or 100mg/kg/day) was performed by gavage during 7days before (pre-treatment) or after sulfite administration. Sulfite decreased creatine kinase and citrate synthase activities, mitochondrial mass, and PGC-1α nuclear content whereas bezafibrate pre-treatment prevented these alterations. Sulfite also diminished cytochrome c oxidase (COX) IV-1 content, glutathione levels and the activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH). On the other hand, catalase activity was increased by sulfite. Bezafibrate pre-treatment prevented the reduction of GPx, GR, GST and G6PDH activities. Finally, sulfite induced glial reactivity and neuronal damage, which were prevented by bezafibrate when administered before or after sulfite administration. Our findings provide strong evidence that sulfite induces neurotoxicity that leads to glial reactivity and neuronal damage. Since bezafibrate exerts neuroprotective effects against sulfite toxicity, it may be an attractive agent for the development of novel therapeutic strategies for SO-deficient patients.

Low maternal care is associated with increased oxidative stress in the brain of lactating rats

Maternal care is crucial for offspring development and licking/grooming patterns can be induced by sensorial, neuroendocrine, and metabolic variations in the CNS. Important brain functions, such as learning and memory, can be influenced by oxidative stress, which can also modulate pathophysiological processes (e.g., depression, anxiety, and other psychiatric disorders). This study evaluated oxidative stress in the hippocampus (HP), olfactory bulb (OB), and plasma in Low-Licking (LL) and High-Licking (HL) lactating rats through superoxide dismutase (SOD) and catalase (CAT) activities, DNA damage (comet assay), and dihydrodichlorofluorescein (DCF) oxidation assay. Results demonstrate that in the HP of LL, the activities of SOD and CAT were increased compared to HL. In the OB, the activities of SOD and CAT were also increased in LL. The comet assay in the HP showed that LL had higher levels of basal damage and increased levels of DNA breaks than HL. In the OB, LL also had higher levels of DNA damage. In the plasma, no difference was observed in either SOD or CAT activities, but the DCF oxidation assay revealed that LL had higher levels of ROS production than HL. In conclusion, we observed that LL mothers showed evidence of increased oxidative stress when compared to HL, suggesting that variations in maternal behavior might be related to these biochemical parameters.