Search

Background. Sustained stress with the overproduction of corticosteroids has been shown to increase reactive oxygen species (ROS) leading to an oxidative stress state. Mitochondria are the main generators of ROS and are directly and detrimentally affected by their overproduction. Neurons depend almost solely on ATP produced by mitochondria in order to satisfy their energy needs and to form synapses, while stress has been proven to alter synaptic plasticity. Emerging evidence underpins that Rhodiola rosea, an adaptogenic plant rich in polyphenols, exerts antioxidant, antistress, and neuroprotective effects. Methods. In this study, the effect of Rhodiola rosea extract (RRE) WS®1375 on neuronal ROS regulation, bioenergetics, and neurite outgrowth, as well as its potential modulatory effect on the brain derived neurotrophic factor (BDNF) pathway, was evaluated in the human neuroblastoma SH-SY5Y and the murine hippocampal HT22 cell lines. Stress was induced using the corticosteroid dexamethasone. Results. RRE increased bioenergetics as well as cell viability and scavenged ROS with a similar efficacy in both cells lines and counteracted the respective corticosteroid-induced dysregulation. The effect of RRE, both under dexamethasone-stress and under normal conditions, resulted in biphasic U-shape and inverted U-shape dose response curves, a characteristic feature of adaptogenic plant extracts. Additionally, RRE treatment promoted neurite outgrowth and induced an increase in BDNF levels. Conclusion. These findings indicate that RRE may constitute a candidate for the prevention of stress-induced pathophysiological processes as well as oxidative stress. Therefore, it could be employed against stress-associated mental disorders potentially leading to the development of a condition-specific supplementation.

(1) Background: While the antidepressant effects of aerobic exercise (AE) are well documented, fewer studies have examined impact of AE as an add-on treatment. Moreover, various effects on neurobiological variables have been suggested. This study examines effects of AE on Cortisol Awakening Reaction (CAR), serum Brain Derived Neurotrophic Factor (sBDNF), Tumor Necrosis Factor alpha (TNF-alpha) and sleep. (2) Methods: Inpatients with moderate-to-severe depression (N = 43) were randomly assigned to the AE or stretching condition (active control) taking place 3x/week for 6 weeks. CAR, sBDNF and TNF-alpha were assessed at baseline, after 2 weeks and post-intervention. The 17-item Hamilton Depression Rating Scale (HDRS17), subjective sleep quality measured by the Pittsburgh Sleep Quality Index (PSQI) and polysomnography (PSG) were obtained at baseline and post-intervention. (3) Results: Stress axis activity decreased in both groups from baseline to post-intervention. sBDNF showed a significant increase over time, whereas the number of awakenings significantly decreased. No significant time by group interactions were detected for any of the study variables. Correlational analyses showed that higher improvements in maximum oxygen capacity (VO2max) from baseline to post-intervention were associated with reduced scores on the HDRS17, PSQI and REM-latency post-intervention. (4) Conclusions: While some neurobiological variables improved during inpatient treatment (CAR, sBDNF), no evidence was found for differential effects between AE and an active control condition (stretching). However, patients in which cardiorespiratory fitness increased showed higher improvements in depression severity and depression-related sleep-parameters.

Neurosteroids are steroids synthetized in the nervous system, with the first step of steroidogenesis taking place within mitochondria with the synthesis of pregnenolone. They exert important brain-specific functions by playing a role in neurotransmission, learning and memory processes, and neuroprotection. Here, we show for the first time that mitochondrial neurosteroidogenesis follows a circadian rhythm and correlates with the rhythmic changes in mitochondrial morphology. We used synchronized human A172 glioma cells, which are steroidogenic cells with a functional core molecular clock, to show that pregnenolone levels and translocator protein (TSPO) are controlled by the clock, probably via circadian regulation of mitochondrial fusion/fission. Key findings were recapitulated in mouse brains. We also showed that genetic or pharmacological abrogation of fusion/fission activity, as well as disturbing the core molecular clock, abolished circadian rhythms of pregnenolone and TSPO. Our findings provide new insights into the crosstalk between mitochondrial function (here, neurosteroidogenesis) and circadian cycles.

Background: Occupational burnout is both a serious public and individual health concern. Psychopharmacological and psychological interventions are often employed, while interventions involving physical activity have been less frequently studied. The aims of the present study were (1) to investigate the effects of physical activity on mitochondrial activity levels and symptoms of burnout, (2) to compare the mitochondrial activity levels and symptoms of burnout of individuals suffering burnout with those of healthy controls (HCs), and (3) to explore the associations between mitochondrial activity and burnout symptoms. Methods: Twelve males with burnout (mean age: M = 45.8 years) took part in the study. At baseline and after 12 weeks of an intervention involving physical activity, participants completed questionnaires covering symptoms of burnout and depression. In parallel, blood samples were taken to measure changes in mitochondrial functional outcomes, such as ATP levels, oxygen consumption and complex I. For comparison, baseline values of healthy controls (HCs; depression and burnout questionnaires; blood samples) were assessed. Results: Over time, symptoms of burnout (emotional exhaustion and depersonalization) and depression significantly decreased in participants with burnout (large effect sizes) but remained significantly higher than those of HCs (medium to large effect sizes). Personal accomplishment increased over time (medium effect size) but was still lower than for HCs (large effect size). At baseline and compared to HCs, individuals with burnout had significantly lower ATP levels of mitochondrial functional outcomes. Over time, mitochondrial activity levels increased among individuals with burnout. High baseline mitochondrial activity was significantly correlated with lower depression and burnout scores both at baseline and at the end of the study. Conclusions: In individuals with burnout, regular physical activity had positive effects on mitochondrial activity and on symptoms of burnout and depression. However, when compared to healthy controls, full remission was not achieved.

Background: Gelsemium sempervirens (GS) is a traditional medicinal plant, described at ultra-low doses as a remedy for a variety of psychological and behavioral symptoms of anxiety and depression. Changes in neural plasticity have been shown to play a significant role in the onset and development of those mental illnesses. Mitochondria play an extremely important role in the central nervous system by being the main energy producer through the oxidative phosphorylation and being involved particularly in the regulation of cell survival or death, as well as synaptic plasticity. Neurite outgrowth is the differentiation process by which neurons establish synapses through the protrusion of neurons and their extension. Methods: Because the effects of GS dilutions on mitochondrial function and neuroplasticity remain elusive, we aimed to investigate whether a treatment with GS at low doses (centesimal dilutions, C) improved bioenergetics parameters such as ATP production, mitochondrial respiration as well as cellular glycolysis before to characterize its effects on neurite outgrowth. Nerve growth factor (NGF), which is known as a promotor of cell growth and survival, was used as a positive control. Results: Our results demonstrate that GS dilutions (3C and 5C) efficiently ameliorated the bioenergetics of SH-SY5Y neuroblastoma cells by increasing cellular ATP level and mitochondrial respiration as well as promoting the cell survival. In addition, GS dilutions significantly improved neurite extension in the 2D as well as 3D culture model after 3 days of treatment. 3C and 5C dilutions showed similar functional effects than those obtained with the positive control nerve growth factor (NGF). Conclusions: These findings indicate that GS dilutions modulate the mitochondrial bioenergetic phenotype and improve the neurite formation. The mitochondrial function improving properties of GS dilutions might represent one possible important pathway contributing to its neuroprotective effectiveness. Key words: Gelsemium dilutions, mitochondria, bioenergetics, neurite outgrowth.

BackgroundStandardized Ginkgo biloba extract (GBE) has demonstrated efficacy in the cognitive functional neuropsychiatric symptoms of patients with Alzheimer's disease (AD). With regard to its underlying molecular mode of action, first evidence was provided that GBE was able to modulate neuronal outgrowth in vitro, but the mechanisms underlying GBE effects on neuroplasticity remain unclear.Methodology/principal findingsIn this study, we investigated the effect of GBE on neurite outgrowth using SH-SY5Y neuroblastoma cells in a 2D and 3D surface culture. The effects of the GBE LI1370 on neuroplasticity and neurite outgrowth were compared to those of nerve growth factor (NGF, 50 ng/ml) which was used as a positive control. We evaluated several parameters of neurite outgrowth such as the neurite number, total neurite length and extend of branching. Our findings showed that GBE (10 and 100 μg/ml) significantly increased neurite outgrowth in the 2D as well as 3D culture model after 3 days of treatment with a comparable effect than that NGF. The use of the 3D cell culture allowed us to better reproduce the in vivo neuronal microenvironment for the evaluation the neurite formation after GBE treatment. In addition, we assessed the effects of GBE on the Akt/mTOR pathway, which is known to promote neuroplasticity induced by nerve growth factors. We showed that GBE treatment induced an increase of phosphorylated IGF1R (Tyr1135/Tyr1136), Akt (Ser473), TSC2 (Ser939), mTOR (Ser2448), PTEN (Ser380) and GSK3β (Ser9).ConclusionTogether, these findings indicate that GBE promotes neurite growth and activates the PI3K/Akt/mTOR pathway suggesting that this plant extract supports neuronal plasticity.

Alzheimer’s disease (AD) is the most common form of dementia affecting people mainly in their sixth decade of life and at a higher age. It is an extensively studied neurodegenerative disorder yet incurable to date. While its main postmortem brain hallmarks are the presence of amyloid-βplaques and hyperphosphorylated tau tangles, the onset of the disease seems to be largely correlated to mitochondrial dysfunction, an early event in the disease pathogenesis. AD is characterized by flawed energy metabolism in the brain and excessive oxidative stress, processes that involve less adenosine triphosphate (ATP) and more reactive oxygen species (ROS) production respectively. Mitochondria are at the center of both these processes as they are responsible for energy and ROS generation through mainly oxidative phosphorylation. StandardizedGinkgo bilobaextract (GBE), resveratrol, and phytoestrogens as well as the neurosteroid allopregnanolone have shown not only some mitochondria-modulating properties but also significant antioxidant potential inin vitroandin vivostudies. According to our review of the literature, GBE, resveratrol, allopregnanolone, and phytoestrogens showed promising effects on mitochondria in a descending evidence order and, notably, this order pattern is in line with the existing clinical evidence level for each entity. In this review, the effects of these four entities are discussed with special focus on their mitochondria-modulating effects and their mitochondria-improving and antioxidant properties across the spectrum of cognitive decline-related disorders. Evidence from preclinical and clinical studies on their mechanisms of action are summarized and highlighted.

Translocator protein 18 kDa (TSPO) is a mitochondrial protein located in the outer membrane and involved in cholesterol translocation, a prerequisite for steroid biosynthesis. TSPO modulation also appears to play a role in other mitochondrial functions, including mitochondrial respiration and cell survival. In the central nervous system, its expression is up‐regulated in neuropathology such as Alzheimer's disease (AD). Previously, we demonstrated that two new TSPO ligands, named 2a and 2b, stimulated pregnenolone synthesis and ATP production in a cellular model of AD overproducing β‐amyloid peptide. The present study aimed to evaluate the impact of the new TSPO ligands on mitochondrial dysfunction in a cellular model of AD‐related tauopathy (human neuroblastoma cells SH‐SY5Y stably overexpressing the P301L‐mutant Tau) presenting mitochondrial impairments, including a decreased ATP synthesis and mitochondrial membrane potential, as well as a decrease in pregnenolone synthesis compared to control cells. The effects of our new ligands were compared with those of TSPO ligands described in the literature (XBD173, SSR‐180,575 and Ro5‐4864). The TSPO ligands 2a and 2b exerted beneficial mitochondrial modulatory effects by increasing ATP levels and mitochondrial membrane potential, paralleled by an increase of pregnenolone levels in mutant Tau cells, as well as in control cells. The compounds 2a and 2b showed effects on mitochondrial activity similar to those obtained with the TSPO ligands of reference. These findings indicate that the new TSPO ligands modulate the mitochondrial bioenergetic phenotype as well as the de novo synthesis of neurosteroids in a cellular model of AD‐related tauopathy, suggesting that these compounds could be potential new therapeutic tools for the treatment of AD.

Mitochondria play an essential role in the generation of steroid hormones including the female sex hormones. These hormones are, in turn, able to modulate mitochondrial activities. Mitochondria possess crucial roles in cell maintenance, survival and well-being, because they are the main source of energy as well as of reactive oxygen species (ROS) within the cell. The impairment of these important organelles is one of the central features of aging. In women's health, estrogen plays an important role during adulthood not only in the estrous cycle, but also in the brain via neuroprotective, neurotrophic and antioxidant modes of action. The hypestrogenic state in the peri- as well as in the prolonged postmenopause might increase the vulnerability of elderly women to brain degeneration and age-related pathologies. However, the underlying mechanisms that affect these processes are not well elucidated. Understanding the relationship between estrogen and mitochondria might therefore provide better insights into the female aging process. Thus, in this review, we first describe mitochondrial dysfunction in the aging brain. Second, we discuss the estrogen-dependent actions on the mitochondrial activity, including recent evidence of the estrogen-brain-derived neurotrophic factor and estrogen-sirtuin 3 (SIRT3) pathways, as well as their potential implications during female aging.

Starting from the central benzodiazepine receptor (CBR) ligand CGS-13767, we designed a series of imidazoquinazolinone derivatives acting as 18 kDa translocator protein (TSPO) ligands, and deprived of affinity for CBR. These compounds, as well as ligands of reference (Ro5-4864, XBD173, SSR180575), were assessed for their ability to restore neurosteroidogenesis and energy production in SH-SY5Y neuroblastoma cell lines expressing amyloid protein precursor (APP). Our results show the potential neuroprotective effect of TSPO ligands, but highlight a strong discrepancy in the active concentrations, nanomolar for ATP production while pregnenolone production is restored in the micromolar range.

Allopregnanolone (AP) is supposed to exert beneficial actions including anxiolysis, analgesia, neurogenesis and neuroprotection. However, although mitochondrial dysfunctions are evidenced in neurodegenerative diseases, AP actions against neurodegeneration-induced mitochondrial deficits have never been investigated. Also, the therapeutic exploitation of AP is limited by its difficulty to pass the liver and its rapid clearance after sulfation or glucuronidation of its 3-hydroxyl group. Therefore, the characterization of novel potent neuroprotective analogs of AP may be of great interest. Thus, we synthesized a set of AP analogs (ANS) and investigated their ability to counteract APP-overexpression-evoked bioenergetic deficits and to protect against oxidative stress-induced death of control and APP-transfected SH-SY5Y cells known as a reliable cellular model of Alzheimer's disease (AD). Especially, we examined whether ANS were more efficient than AP to reduce mitochondrial dysfunctions or bioenergetic decrease leading to neuronal cell death. Our results showed that the ANS BR 297 exhibits notable advantages over AP with regards to both protection of mitochondrial functions and reduction of oxidative stress. Indeed, under physiological conditions, BR 297 does not promote cell proliferation but efficiently ameliorates the bioenergetics by increasing cellular ATP level and mitochondrial respiration. Under oxidative stress situations, BR 297 treatment, which decreases ROS levels, improves mitochondrial respiration and cell survival, appears more potent than AP to protect control and APP-transfected cells against H2O2-induced death. Our findings lend further support to the neuroprotective effects of BR 297 emphasizing this analog as a promising therapeutic tool to counteract age- and AD-related bioenergetic deficits. journal article 2017 Mar 2016 12 13 imported