Astrocyte-synthesized oleic acid behaves as a neurotrophic factor for neurons

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Mix of almond baru (Dipteryx alata Vog.) and goat whey modulated intestinal microbiota, improved memory and induced anxiolytic like behavior in aged rats

The objective was to evaluate the effects of the consumption of a mix of baru almond and goat whey on memory performance and anxiety parameters related to the intestinal health of rats treated during aging. The animals were divided into three groups and treated by gavage for 10 weeks (n = 10/each group): Control (CT) - distilled water; Baru almond (BA) - 2000 mg of baru/kg of body weight; and Baru + Whey (BW) - 2000 mg of baru + 2000 mg of goat milk whey/kg of body weight. Anxiety behavior, memory, brain fatty acid profile and fecal microbiota were measured. BA and BW realized less grooming, spent more time in the central area of the open field and the open arms, and realized more head dipping in the elevated plus maze. A higher rate of exploration of the new object in the short and long-term memory was observed in BA and BW. There was an increase in the deposition of MUFAs and PUFAs and oleic acid in the brain of BA and BW. Regarding spatial memory, BA and BW performed better, with an emphasis on BW. There was a beneficial modulation of the fecal microbiota with a reduction of the pathogenic genus Clostridia_UFC-014 in BA and BW and an increase in the abundance of metabolic pathways of interest in the brain-gut axis. Thus, consumption of the mix is efficient in beneficially altering the intestinal microbiota, improving memory and anxiolytic-like behavior in rats during aging.

Fatty Acids: A Safe Tool for Improving Neurodevelopmental Alterations in Down Syndrome?

The triplication of chromosome 21 causes Down syndrome (DS), a genetic disorder that is characterized by intellectual disability (ID). The causes of ID start in utero, leading to impairments in neurogenesis, and continue into infancy, leading to impairments in dendritogenesis, spinogenesis, and connectivity. These defects are associated with alterations in mitochondrial and metabolic functions and precocious aging, leading to the early development of Alzheimer’s disease. Intense efforts are currently underway, taking advantage of DS mouse models to discover pharmacotherapies for the neurodevelopmental and cognitive deficits of DS. Many treatments that proved effective in mouse models may raise safety concerns over human use, especially at early life stages. Accumulating evidence shows that fatty acids, which are nutrients present in normal diets, exert numerous positive effects on the brain. Here, we review (i) the knowledge obtained from animal models regarding the effects of fatty acids on the brain, by focusing on alterations that are particularly prominent in DS, and (ii) the progress recently made in a DS mouse model, suggesting that fatty acids may indeed represent a useful treatment for DS. This scenario should prompt the scientific community to further explore the potential benefit of fatty acids for people with DS.

The Majority of Brain Palmitic Acid is Maintained by Lipogenesis from Dietary Sugars and is Augmented in Mice fed Low Palmitic Acid Levels from Birth

Previously, results from studies investigating if brain palmitic acid (16:0; PAM) was maintained by either dietary uptake or lipogenesis de novo (DNL) varied. Here, we utilize naturally occurring carbon isotope ratios (¹³ C/¹² C; δ¹³ C) to uncover the origin of brain PAM. Additionally, we explored brain and liver fatty acid concentration, total brain metabolomic profile, and behaviour. BALB/c dams were equilibrated onto either a low PAM diet (LP; <2%) or high PAM diet (HP; >95%) prior to producing one generation of offspring. Offspring stayed on the respective diet of the dam until 15-weeks of age, at which time the Open Field test was conducted in the offspring, prior to euthanasia and tissue lipid extraction. Although liver PAM was lower in offspring fed the LP diet, as well as female offspring, brain PAM was not affected by diet or sex. Across offspring of either sex on both diets, brain ¹³ C-PAM revealed compared to dietary uptake, DNL from dietary sugars contributed 68.8%-79.5% and 46.6%-58.0% to the total brain PAM pool by both peripheral and local brain DNL, and local brain DNL alone, respectively. DNL was augmented in offspring fed the LP diet, and the ability to upregulate DNL in the liver or the brain depended on sex. Anxiety-like behaviours were decreased in offspring fed the LP diet and were correlated with markers of LP diet consumption including increased liver ¹³ C-PAM, warranting further investigation. Altogether, our results indicate that DNL from dietary sugars is a compensatory mechanism to maintain brain PAM in response to a LP diet.

SCD Inhibition Protects from α-Synuclein-Induced Neurotoxicity But Is Toxic to Early Neuron Cultures

Here, we report the independent discovery and validation of stearoyl-CoA desaturase (SCD) as a modulator of α-synuclein (αSyn)-induced pathology and toxicity in cell-based Parkinson’s disease (PD) models. We identified SCD as top altered gene from transcriptional profiling in primary neurons exogenously expressing αSyn with the amplified familial PD mutation 3K. Thus, we sought to further explore SCD as a therapeutic target in neurodegeneration. We report that SCD inhibitors are toxic to early human and rat neuron cultures while displaying minimal toxicity to late cultures. The fatty acid product of SCD, oleic acid (OLA), fully rescues this toxicity in early cultures, suggesting on-target toxicity. Furthermore, SCD inhibition rescues αSyn 3K-induced toxicity in late primary neurons. We also confirm that SCD inhibitors reduce formation of αSyn accumulations, while OLA increases these accumulations in an αSyn 3K neuroblastoma model. However, we identify a caveat with this model where αSyn 3K levels can be suppressed by high SCD inhibitor concentrations, obscuring true effect size. Further, we show that both SCD1 or SCD5 knock-down reduce αSyn 3K accumulations and toxicity, making both a putative drug target. Overall, we confirm key findings of published data on SCD inhibition and its benefits in αSyn accumulation and stress models. The differential neurotoxicity induced by SCD inhibition based on neuron culture age must be accounted for when researching SCD in neuron models and has potential clinical implications. Lastly, our gene profiling studies also revealed novel putative genes connected to αSyn neurotoxicity that are worth further study.

Fatty acids and beyond: Age and Alzheimer's disease related changes in lipids reveal the neuro-nutraceutical potential of lipids in cognition

Lipids are essential in maintaining brain function, and lipid profiles have been reported to be altered in aged and Alzheimer's disease (AD) brains as compared to healthy mature brains. Both age and AD share common metabolic hallmarks such as increased oxidative stress and perturbed metabolic function, and age remains the most strongly correlated risk factor for AD, a neurodegenerative disease. A major accompanying pathological symptom of these conditions is cognitive impairment, which is linked with changes in lipid metabolism. Thus, nutraceuticals that affect brain lipid metabolism or lipid levels as a whole have the potential to ameliorate cognitive decline. Lipid analyses and lipidomic studies reveal changes in specific lipid types with aging and AD, which can identify potential lipid-based nutraceuticals to restore the brain to a healthy lipid phenotype. The brain lipid profile can be influenced directly with dietary administration of lipids themselves, although because of synergistic effects of nutrients it may be more useful to consider a multi-component diet rather than single nutrient supplementation. Gut microbiota also serve as a source of beneficial lipids, and the value of treatments that manipulate the composition of gut microbiome should not be ignored. Lastly, instead of direct supplementation, compounds that affect pathways involved with lipid metabolism should also be considered as a way of manipulating lipid levels to improve cognition. In this review, we briefly discuss the role of lipids in the brain, the changing lipid profile in AD, current research on lipid-based nutraceuticals and their therapeutic potential to combat cognitive impairment.

Nervonic acid level in cerebrospinal fluid is a candidate biomarker for depressive and manic symptoms: A pilot study

OBJECTIVE

Our previous metabolomics study showed that the plasma nervonic acid levels were higher in patients with major depressive disorder (MDD) than those in healthy controls and patients with bipolar disorder (BD). To examine whether the nervonic acid levels differ in the central nervous system, we investigated the levels in the cerebrospinal fluid (CSF) of patients with MDD, BD, and healthy controls.

METHODS

Nervonic acid levels in CSF were measured by gas chromatography time-of-flight mass spectrometry. The participants included 30 patients with MDD, 30 patients with BD, and 30 healthy controls.

RESULTS

In contrast to our previous study, no significant differences were found in the nervonic acid level in the CSF among the patients with MDD, BD, and the healthy controls. Though no significant state-dependent changes were found among the three groups, we did observe a significant negative correlation between the nervonic acid levels and depressive symptoms in the depressive state of patients with MDD and BD (r = -0.38, p = .046). Further, a significant positive correlation was found between the nervonic acid levels and manic symptoms in the manic state of patients with BD (r = 0.79, p = .031).

CONCLUSION

The nervonic acid levels in the CSF did not differ among the patients with MDD, BD, and the healthy controls; however, a significant negative correlation with depressive symptoms and a positive correlation with manic symptoms was observed. Thus, the nervonic acid levels in the CSF may be a candidate biomarker for mood symptoms.

Functional and transcriptional characterization of complex neuronal co-cultures

Brain-on-a-chip systems are designed to simulate brain activity using traditional in vitro cell culture on an engineered platform. It is a noninvasive tool to screen new drugs, evaluate toxicants, and elucidate disease mechanisms. However, successful recapitulation of brain function on these systems is dependent on the complexity of the cell culture. In this study, we increased cellular complexity of traditional (simple) neuronal cultures by co-culturing with astrocytes and oligodendrocyte precursor cells (complex culture). We evaluated and compared neuronal activity (e.g., network formation and maturation), cellular composition in long-term culture, and the transcriptome of the two cultures. Compared to simple cultures, neurons from complex co-cultures exhibited earlier synapse and network development and maturation, which was supported by localized synaptophysin expression, up-regulation of genes involved in mature neuronal processes, and synchronized neural network activity. Also, mature oligodendrocytes and reactive astrocytes were only detected in complex cultures upon transcriptomic analysis of age-matched cultures. Functionally, the GABA antagonist bicuculline had a greater influence on bursting activity in complex versus simple cultures. Collectively, the cellular complexity of brain-on-a-chip systems intrinsically develops cell type-specific phenotypes relevant to the brain while accelerating the maturation of neuronal networks, important features underdeveloped in traditional cultures.

Prenatal Administration of Oleic Acid or Linolenic Acid Reduces Neuromorphological and Cognitive Alterations in Ts65dn Down Syndrome Mice

BACKGROUND

The cognitive impairments that characterize Down syndrome (DS) have been attributed to brain hypocellularity due to neurogenesis impairment during fetal stages. Thus, enhancing prenatal neurogenesis in DS could prevent or reduce some of the neuromorphological and cognitive defects found in postnatal stages.

OBJECTIVES

As fatty acids play a fundamental role in morphogenesis and brain development during fetal stages, in this study, we aimed to enhance neurogenesis and the cognitive abilities of the Ts65Dn (TS) mouse model of DS by administering oleic or linolenic acid.

METHODS

In total, 85 pregnant TS females were subcutaneously treated from Embryonic Day (ED) 10 until Postnatal Day (PD) 2 with oleic acid (400 mg/kg), linolenic acid (500 mg/kg), or vehicle. All analyses were performed on their TS and Control (CO) male and female progeny. At PD2, we evaluated the short-term effects of the treatments on neurogenesis, cellularity, and brain weight, in 40 TS and CO pups. A total of 69 TS and CO mice were used to test the long-term effects of the prenatal treatments on cognition from PD30 to PD45, and on neurogenesis, cellularity, and synaptic markers, at PD45. Data were compared by ANOVAs.

RESULTS

Prenatal administration of oleic or linolenic acid increased the brain weight (+36.7% and +45%, P < 0.01), the density of BrdU (bromodeoxyuridine)- (+80% and +115%; P < 0.01), and DAPI (4',6-diamidino-2-phenylindole)-positive cells (+64% and +22%, P < 0.05) of PD2 TS mice with respect to the vehicle-treated TS mice. Between PD30 and PD45, TS mice prenatally treated with oleic or linolenic acid showed better cognitive abilities (+28% and +25%, P < 0.01) and a higher density of the postsynaptic marker PSD95 (postsynaptic density protein 95) (+65% and +44%, P < 0.05) than the vehicle-treated TS animals.

CONCLUSION

The beneficial cognitive and neuromorphological effects induced by oleic or linolenic acid in TS mice suggest that they could be promising pharmacotherapies for DS-associated cognitive deficits.

Fatty Acids and Antioxidants in Multiple Sclerosis: Therapeutic Role of GEMSP

Multiple sclerosis is a high-frequency neurological disorder in young adults. Although there are some genetic and environmental factors that have been related to the onset of the disease, these are still not completely understood and nowadays multiple sclerosis can neither be prevented, nor its symptom effectively treated due to disease heterogeneity. For this reason, the search of prognostic factors and new therapeutic compounds for MS has long aroused among clinicians and researchers. Among these therapeutic compounds, GEMSP, which consists of a mixture of functional constituents as fatty acids, antioxidants, free radical scavengers and amino acids linked individually to poly-L-Lysine (PL), is emerging as a promising drug for MS treatment. Pre-clinical studies using GEMSP have demonstrated that this drug strongly inhibits brain leukocyte infiltration and completely abolishes experimental autoimmune encephalomyelitis. In addition, in an open clinical trial in humans treated with GEMSP, in 72% of the cases, a positive evolution of the state of the MS patients treated with GMSP was observed. In this review a biochemical characterization of main constituents of GEMSP, which include fatty acids as oleic acid, linoleic acid or azelaic acid and the antioxidants alpha-tocopherol or ascorbic acid, will be provided in order to understand their proved therapeutic effects in MS.

Converging and Differential Brain Phospholipid Dysregulation in the Pathogenesis of Repetitive Mild Traumatic Brain Injury and Alzheimer's Disease

Repetitive mild traumatic brain injury (rmTBI) is a major epigenetic risk factor for Alzheimer’s disease (AD). The precise nature of how rmTBI leads to or precipitates AD pathology is currently unknown. Numerous neurological conditions have shown an important role for dysfunctional phospholipid metabolism as a driving factor for the pathogenesis of neurodegenerative diseases. However, the precise role in rmTBI and AD remains elusive. We hypothesized that a detailed phospholipid characterization would reveal profiles of response to injury in TBI that overlap with age-dependent changes in AD and thus provide insights into the TBI-AD relationship. We employed a lipidomic approach examining brain phospholipid profiles from mouse models of rmTBI and AD. Cortex and hippocampal tissue were collected at 24 h, 3, 6, 9, and 12 months post-rmTBI, and at ages representing ‘pre’, ‘peri’ and ‘post’ onset of amyloid pathology (i.e., 3, 9, 15 months-old). Total levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), LysoPE, and phosphatidylinositol (PI), including their monounsaturated, polyunsaturated and saturated fatty acid (FA) containing species were significantly increased at acute and/or chronic time points post-injury in both brain regions. However, levels of most phospholipid species in PS1/APP mice were nominal in the hippocampus, while in the cortex, levels were significantly decreased at ages post-onset of amyloid pathology. Sphingomyelin and LysoPC levels showed coincidental trends in our rmTBI and AD models within the hippocampus, an increase at acute and/or chronic time points examined. The ratio of arachidonic acid (omega-6 FA) to docosahexaenoic acid (omega-3 FA)-containing PE species was increased at early time points in the hippocampus of injured versus sham mice, and in PS1/APP mice there was a coincidental increase compared to wild type littermates at all time points. This study demonstrates some overlapping and diverse phospholipid profiles in rmTBI and AD models. Future studies are required to corroborate our findings in human post-mortem tissue. Investigation of secondary mechanisms triggered by aberrant downstream alterations in bioactive metabolites of these phospholipids, and their modulation at the appropriate time-windows of opportunity could help facilitate development of novel therapeutic strategies to ameliorate the neurodegenerative consequences of rmTBI or the potential triggering of AD pathogenesis by rmTBI.

Maternal Supplementation With Avocado (Persea americana Mill.) Pulp and Oil Alters Reflex Maturation, Physical Development, and Offspring Memory in Rats

Avocado (Persea americana Mill.) is an oleaginous fruit source of fatty acids with high levels of neuroprotective phytocomplexes. The objective of this study was to evaluate the development of reflex and somatic maturation, fatty acid profiles in the brain, and memory in different stages of life in the offspring of dams supplemented with avocado pulp and oil during gestation and lactation. The dams were randomly divided into three groups (n = 15 pups/group), and recieved by gavage supplementation: control group (CG)-distilled water; Avocado Oil (AO)-3,000 mg avocado oil/kg animal weight, and Avocado Pulp (AP)-3,000 mg avocado pulp/kg animal weight. We performed the following tests: Analysis of Somatic Development and Ontogeny of Postnatal Reflex (T0 to T21), the Open Field Habituation Test and the Object Recognition Test (ORT) in the adolescent (T45) and adult (T90) phases. The cerebral fatty acids content was evaluated at times T0, T21, T45, and T90. The results were analyzed using the statistical program GraphPad Prism and significant statistics were considered when p < 0.05. Acceleration of reflex maturation and reflex ontogeny was observed in the offspring of AO and AP fed dams, with the results being more pronounced in the pulp fed group (p < 0.05). All groups presented a decrease in the ambulation parameter in the second exposure to the Open Field Habituation Test, at T45 and T90 (p < 0.05). In the ORT, the AO and AP offspring presented memory improvements in the short and long term in the adult and adolescent phases (p < 0.05). The results of the brain fatty acid profiles presented higher polyunsaturated fatty acids (PUFA) content in the AO and AP groups at T21, T45, and T90. The docosahexaenoic fatty acid (DHA) content was higher at T21 (AO and AP), at T45 (AO and AP), and at T90 (AP) (p < 0.05). The arachidonic acid (ARA) content was higher at T45 (AO and AP), and at T90 (AO) (p < 0.05). Maternal supplementation with avocado oil and pulp anticipates reflex maturation and somatic postnatal development, and improves memory during the adolescent and adult phases.

Disruption in Brain Phospholipid Content in a Humanized Tau Transgenic Model Following Repetitive Mild Traumatic Brain Injury

Repetitive mild traumatic brain injury (mTBI) is a risk factor for the development of neurodegenerative diseases such as chronic traumatic encephalopathy typified by immunoreactive tau aggregates in the depths of the sulci. However, the underlying neurobiological mechanisms involved have not been largely explored. Phospholipids are important molecules which form membrane lipid bilayers; they are ubiquitous to every cell in the brain, and carry out a host of different functions. Imbalance in phospholipid metabolism, signaling and transport has been documented in some neurological conditions. However, not much is currently known about their roles in repetitive mTBI and how this may confer risk for the development of age-related neurodegenerative diseases. To address this question, we designed a longitudinal study (24 h, 3, 6, 9, and 12 months post-injury) to comprehensively investigate mTBI dependent brain phospholipid profiles compared to sham counterparts. We use our established mouse model of repetitive mTBI that has been extensively characterized up to 1-year post-injury in humanized tau (hTau) mice, which expresses all six human tau isoforms, on a null murine background. Our data indicates a significant increase in sphingomyelin, phosphatidylethanolamine (PE), phosphatidylcholine (PC), and derivative lysoPE and lysoPC at acute and/or sub-acute time points post-injury within the cortex and hippocampus. There was also a parallel increase at early time points in monounsaturated, polyunsaturated and saturated fatty acids. Omega-6 (arachidonic acid) to omega-3 (docosahexaenoic acid) fatty acid ratio for PE and PC species was increased also at 24 h and 3 months post-injury in both hippocampus and cortex. The long-term consequences of these early changes in phospholipids on neuronal and non-neuronal cell function is unclear, and warrants further study. Understanding phospholipid metabolism, signaling and transport following TBI could be valuable; they may offer novel targets for therapeutic intervention not only in TBI but other neurodegenerative diseases.

Low omega-6/omega-3 ratio in a maternal protein-deficient diet promotes histone-3 changes in progeny neural cells and favors leukemia inhibitory factor genetranscription

Omega-3 (n-3) fatty acids modulate epigenetic changes critical to genesis and differentiation of neural cells. Conversely, maternal protein-malnutrition can negatively modify these changes. This study investigated whether a low n-6/n-3 ratio in a maternal diet could favor histone-3 (H3) modifications, gene transcription and differentiation in the offspring neural cells even under protein-deficiency. Female rats fed a control (Ct), or 3 types of multideficient diets differing in protein levels or linoleic/alpha-linolenic fatty acid ratios (RBD, RBD-C, RBD-SO) from 30 days prior to mating and during pregnancy. Cerebral cortex tissue and cortical cultures of progeny embryonic neurons and postnatal astrocytes were analyzed. H3K9 acetylation and H3K27 or H3K4 di-methylation levels were assessed by flow cytometry and/or immunocytochemistry. In astrocyte cultures and cortical tissue, the GFAP protein levels were assessed. Glial derived neurotrophic factor (GDNF) and leukemia inhibitory factor (LIF) gene expression were evaluated in the cortical tissue. GFAP levels were similar in astrocytes of Ct, RBD and RBD-C, but 65% lower in RBD-SO group. Higher levels of H3K9Ac were found in the neurons and H3K4Me2 in the astrocytes of the RBD group. No intergroup difference in the cortical GDNF mRNA expression or the H3K27Me2 levels in astrocytes was detected. LIF mRNA levels were higher in the RDB (P=.002) or RBD-C (P=.004) groups than in the control. The findings indicate the importance of dietary n-3 availability for the brain, even under a protein-deficient condition, inducing Histone modifications and increasing LIF gene transcription, involved in neural cell differentiation and reactivity.

Oleic Acid in the Ventral Tegmental Area Inhibits Feeding, Food Reward, and Dopamine Tone

Long-chain fatty acids (FAs) act centrally to decrease food intake and hepatic glucose production and alter hypothalamic neuronal activity in a manner that depends on FA type and cellular transport proteins. However, it is not known whether FAs are sensed by ventral tegmental area (VTA) dopamine (DA) neurons to control food-motivated behavior and DA neurotransmission. We investigated the impact of the monounsaturated FA oleate in the VTA on feeding, locomotion, food reward, and DA neuronal activity and DA neuron expression of FA-handling proteins and FA uptake. A single intra-VTA injection of oleate, but not of the saturated FA palmitate, decreased food intake and increased locomotor activity. Furthermore, intra-VTA oleate blunted the rewarding effects of high-fat/sugar food in an operant task and inhibited DA neuronal firing. Using sorted DA neuron preparations from TH-eGFP mice we found that DA neurons express FA transporter and binding proteins, and are capable of intracellular transport of long-chain FA. Finally, we demonstrate that a transporter blocker attenuates FA uptake into DA neurons and blocks the effects of intra-VTA oleate to decrease food-seeking and DA neuronal activity. Together, these results suggest that DA neurons detect FA and that oleate has actions in the VTA to suppress DA neuronal activity and food seeking following cellular incorporation. These findings highlight the capacity of DA neurons to act as metabolic sensors by responding not only to hormones but also to FA nutrient signals to modulate food-directed behavior.

High Content Analysis of Hippocampal Neuron-Astrocyte Co-cultures Shows a Positive Effect of Fortasyn Connect on Neuronal Survival and Postsynaptic Maturation

Neuronal and synaptic membranes are composed of a phospholipid bilayer. Supplementation with dietary precursors for phospholipid synthesis –docosahexaenoic acid (DHA), uridine and choline– has been shown to increase neurite outgrowth and synaptogenesis both in vivo and in vitro. A role for multi-nutrient intervention with specific precursors and cofactors has recently emerged in early Alzheimer's disease, which is characterized by decreased synapse numbers in the hippocampus. Moreover, the medical food Souvenaid, containing the specific nutrient combination Fortasyn Connect (FC), improves memory performance in early Alzheimer's disease patients, possibly via maintaining brain connectivity. This suggests an effect of FC on synapses, but the underlying cellular mechanism is not fully understood. Therefore, we investigated the effect of FC (consisting of DHA, eicosapentaenoic acid (EPA), uridine, choline, phospholipids, folic acid, vitamins B12, B6, C and E, and selenium), on synaptogenesis by supplementing it to primary neuron-astrocyte co-cultures, a cellular model that mimics metabolic dependencies in the brain. We measured neuronal developmental processes using high content screening in an automated manner, including neuronal survival, neurite morphology, as well as the formation and maturation of synapses. Here, we show that FC supplementation resulted in increased numbers of neurons without affecting astrocyte number. Furthermore, FC increased postsynaptic PSD95 levels in both immature and mature synapses. These findings suggest that supplementation with FC to neuron-astrocyte co-cultures increased both neuronal survival and the maturation of postsynaptic terminals, which might aid the functional interpretation of FC-based intervention strategies in neurological diseases characterized by neuronal loss and impaired synaptic functioning.

Safflower Seed Oil, Containing Oleic Acid and Palmitic Acid, Enhances the Stemness of Cultured Embryonic Neural Stem Cells through Notch1 and Induces Neuronal Differentiation

Embryonic neural stem cells (eNSCs) could differentiate into neurons, astrocytes and oligodendrocytes. This study was aimed to determine the effect of safflower seed oil, which contains linoleic acid (LA), oleic acid (OA), and palmitic acid (PA), on cultured eNSC proliferation and differentiation, in comparison to linoleic acid alone. Results showed that safflower seed oil, but not LA, increased significantly the viability and proliferation of eNSCs. Moreover, treatment of NSCs by safflower seed oil, but not LA, resulted in a significant increase in mRNA levels of notch1, hes1, and Ki-67, and protein levels of notch intracellular domain (NICD), in comparison to controls, indicating an enhancement of stemness. Finally, safflower seed oil, but not LA, caused an increase in the number of oligodendrocytes (MBP+), astrocytes (GFAP+) and neurons (β-III tubulin+) of which only the increase in β-III tubulin positive cells was statistically significant. In summary, OA and PA, present in safflower seed oil may prove beneficial for the enhancement of eNSCs and their neuronal differentiation.

Comprehensive investigation of temporal and autism-associated cell type composition-dependent and independent gene expression changes in human brains

The functions of human brains highly depend on the precise temporal regulation of gene expression, and the temporal brain transcriptome profile across lifespan has been observed. The substantial transcriptome alteration in neural disorders like autism has also been observed and is thought to be important for the pathology. While the cell type composition is known to be variable in brains, it remains unclear how it contributes to the temporal and pathological transcriptome changes in brains. Here, we applied a transcriptome deconvolution procedure to an age series RNA-seq dataset of healthy and autism samples, to quantify the contribution of cell type composition in shaping the temporal and autism pathological transcriptome in human brains. We estimated that composition change was the primary factor of both types of transcriptome changes. On the other hand, genes with substantial composition-independent expression changes were also observed in both cases. Those temporal and autism pathological composition-independent changes, many of which are related to synaptic functions, indicate the important intracellular regulatory changes in human brains in both processes.

Follow-up of multiple sclerosis patients treated with Endotherapia (GEMSP)

Endotherapia (GEMSP) is a novel therapeutic approach for multiple sclerosis (MS). The aim of the present study was to demonstrate the efficiency of Endotherapia in the follow-up of 193 patients with MS. The efficiency coefficient that was evaluated was the Expanded Disability Status Scale (EDSS) score, which is a functional scale of MS progression. The evaluated score of each patient during follow-up visits was compared with the theoretical score of the disease progression without GEMSP. The evolution of the EDSS score was evaluated according to the inclusion score. The quantitative global study of the EDSS score highlighted a statistically significant difference between the final average scores of the treatment with GEMSP (M) and worldwide reference (R) groups. The improvement of the M group compared with the R group was 24.5%. According to the final EDSS scores, the study highlighted a difference in favor of the M group with 62.0% for scores ≤3, 7.8% for scores between 3 and 6 and 19.6% for scores ≥6. According to the qualitative evolution of the EDSS scores, the improvements in favor of group M were 49.3% for scores ≤3, 79.1% for scores between 3 and 6 and 19.5% for scores ≥6. The qualitative study of the EDSS score showed a statistically significant success percentage; the success percentages were between 59.1 and 90.0%. In a larger population of MS patients, the data confirm the beneficial effects of GEMSP that were previously reported in pre-clinical and clinical studies. In addition, 78% of patients showed an improvement or deceleration of the disease.

Restrained Phosphatidylcholine Synthesis in a Cellular Model of Down's Syndrome is Associated with the Overexpression of Dyrk1A

Aberrant formation of the cerebral cortex could be attributed to the lack of suitable substrates that direct the migration of neurons. Previous work carried out at our laboratory has shown that oleic acid is a neurotrophic factor. In order to characterize the effect of oleic acid in a cellular model of Down's syndrome (DS), here, we used immortalized cell lines derived from the cortex of trisomy Ts16 and euploid mice. We report that in the plasma membrane of euploid cells, an increase in phosphatidylcholine concentrations occurs in the presence of oleic acid. However, in trisomic cells, oleic acid failed to increase phosphatidylcholine incorporation into the plasma membrane. Gene expression analysis of trisomic cells revealed that the phosphatidylcholine biosynthetic pathway was deregulated. Taken together, these results suggest that the overdose of specific genes in trisomic lines delays differentiation in the presence of oleic acid. The dual-specificity tyrosine (Y) phosphorylation-regulated kinase 1A (DYRK1A) gene is located on human chromosome 21. DYRK1A contributes to intellectual disability and the early onset of Alzheimer's disease in DS patients. Here, we explored the potential role of Dyrk1A in the reduction of phosphatidylcholine concentrations in trisomic cells in the presence of oleic acid. The downregulation of Dyrk1A by small interfering RNA (siRNA) in trisomic cells returned phosphatidylcholine concentrations up to similar levels to those of euploid cells in the presence of oleic acid. Thus, our results highlight the role of Dyrk1A in brain development through the modulation of phosphatidylcholine location, levels and synthesis.

Astrocyte lipid metabolism is critical for synapse development and function in vivo

The brain is considered to be autonomous in lipid synthesis with astrocytes producing lipids far more efficiently than neurons. Accordingly, it is generally assumed that astrocyte-derived lipids are taken up by neurons to support synapse formation and function. Initial confirmation of this assumption has been obtained in cell cultures, but whether astrocyte-derived lipids support synapses in vivo is not known. Here, we address this issue and determined the role of astrocyte lipid metabolism in hippocampal synapse formation and function in vivo. Hippocampal protein expression for the sterol regulatory element-binding protein (SREBP) and its target gene fatty acid synthase (Fasn) was found in astrocytes but not in neurons. Diminishing SREBP activity in astrocytes using mice in which the SREBP cleavage-activating protein (SCAP) was deleted from GFAP-expressing cells resulted in decreased cholesterol and phospholipid secretion by astrocytes. Interestingly, SCAP mutant mice showed more immature synapses, lower presynaptic protein SNAP-25 levels as well as reduced numbers of synaptic vesicles, indicating impaired development of the presynaptic terminal. Accordingly, hippocampal short-term and long-term synaptic plasticity were defective in mutant mice. These findings establish a critical role for astrocyte lipid metabolism in presynaptic terminal development and function in vivo. GLIA 2017;65:670-682.

Migraine Triggers and Oxidative Stress: A Narrative Review and Synthesis

BACKGROUND

Blau theorized that migraine triggers are exposures that in higher amounts would damage the brain. The recent discovery that the TRPA1 ion channel transduces oxidative stress and triggers neurogenic inflammation suggests that oxidative stress may be the common denominator underlying migraine triggers.

OBJECTIVE

The aim of this review is to present and discuss the available literature on the capacity of common migraine triggers to generate oxidative stress in the brain.

METHODS

A Medline search was conducted crossing the terms "oxidative stress" and "brain" with "alcohol," "dehydration," "water deprivation," "monosodium glutamate," "aspartame," "tyramine," "phenylethylamine," "dietary nitrates," "nitrosamines," "noise," "weather," "air pollutants," "hypoglycemia," "hypoxia," "infection," "estrogen," "circadian," "sleep deprivation," "information processing," "psychosocial stress," or "nitroglycerin and tolerance." "Flavonoids" was crossed with "prooxidant." The reference lists of the resulting articles were examined for further relevant studies. The focus was on empirical studies, in vitro and of animals, of individual triggers, indicating whether and/or by what mechanism they can generate oxidative stress.

RESULTS

In all cases except pericranial pain, common migraine triggers are capable of generating oxidative stress. Depending on the trigger, mechanisms include a high rate of energy production by the mitochondria, toxicity or altered membrane properties of the mitochondria, calcium overload and excitotoxicity, neuroinflammation and activation of microglia, and activation of neuronal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. For some triggers, oxidants also arise as a byproduct of monoamine oxidase or cytochrome P450 processing, or from uncoupling of nitric oxide synthase.

CONCLUSIONS

Oxidative stress is a plausible unifying principle behind the types of migraine triggers encountered in clinical practice. The possible implications for prevention and for understanding the nature of the migraine attack are discussed.

Phasic and tonic type A γ-Aminobutryic acid receptor mediated effect of Withania somnifera on mice hippocampal CA1 pyramidal Neurons

Background:

In Nepali and Indian system of traditional medicine, Withania somnifera (WS) is considered as a rejuvenative medicine to maintain physical and mental health and has also been shown to improve memory consolidation.

Objective:

In this study, a methanolic extract of WS (mWS) was applied on mice hippocampal CA1 neurons to identify the receptors activated by the WS.

Materials and Methods:

The whole cell patch clamp recordings were performed on CA1 pyramidal neurons from immature mice (7-20 postnatal days). The cells were voltage clamped at -60 mV. Extract of WS root were applied to identify the effect of mWS.

Results:

The application of mWS (400 ng/μl) induced remarkable inward currents (-158.1 ± 28.08 pA, n = 26) on the CA1 pyramidal neurons. These inward currents were not only reproducible but also concentration dependent. mWS-induced inward currents remained persistent in the presence of amino acid receptor blocking cocktail (AARBC) containing blockers for the ionotropic glutamate receptors, glycine receptors and voltage-gated Na⁺ channel (Control: -200.3 ± 55.42 pA, AARBC: -151.5 ± 40.58 pA, P > 0.05) suggesting that most of the responses by mWS are postsynaptic events. Interestingly, these inward currents were almost completely blocked by broad GABA_A receptor antagonist, bicuculline- 20 μM (BIC) (BIC: -1.46 ± 1.4 pA, P < 0.001), but only partially by synaptic GABA_A receptor blocker gabazine (1 μM) (GBZ: -18.26 ± 4.70 pA, P < 0.01).

Conclusion:

These results suggest that WS acts on synaptic/extrasynaptic GABA_A receptors and may play an important role in the process of memory and neuroprotection via activation of synaptic and extrasynaptic GABA_A receptors.

Oleic acid synthesized by stearoyl-CoA desaturase (SCD-1) in the lateral periventricular zone of the developing rat brain mediates neuronal growth, migration and the arrangement of prospective synapses

Our previous work has shown that oleic acid synthesized by astrocytes in response to serum albumin behaves as a neurotrophic factor in neurons, upregulating the expression of GAP-43 and MAP-2 proteins, which are respectively markers of axonal and dendrite growth. In addition, oleic acid promoted neuron migration and aggregation, resulting in clusters of neurons connected each other by the newly formed neurites. In this work we show that the presence of albumin or albumin plus oleic acid increases neuron migration in cultured explants of the lateral periventricular zone, resulting in an increase in the number of GAP-43-positive neurons leaving the explant. Upon silencing stearoyl-CoA desaturase-1 (SCD-1), a key enzyme in oleic acid synthesis by RNA of interference mostly prevented the effect of albumin but not that of albumin plus oleic acid, suggesting that the oleic acid synthesized due to the effect of albumin would be responsible for the increase in neuron migration. Oleic acid increased doublecortin (DCX) expression in cultured neurons, explants and organotypic slices, suggesting that DCX may mediate in the effect of oleic acid on neuron migration. The effect of oleic acid on neuron migration may be destined for the formation of synapses because the presence of oleic acid increased the expression of synaptotagmin and that of postsynaptic density protein (PDS-95), respectively markers of the pre- and postsynaptic compartments. In addition, confocal microscopy revealed the occurrence of points of colocalization between synaptotagmin and PDS-95, which is consistent with the idea that oleic acid promotes synapse arrangement.

Novel cell separation method for molecular analysis of neuron-astrocyte co-cultures

Over the last decade, the importance of astrocyte-neuron communication in neuronal development and synaptic plasticity has become increasingly clear. Since neuron-astrocyte interactions represent highly dynamic and reciprocal processes, we hypothesized that many astrocyte genes may be regulated as a consequence of their interactions with maturing neurons. In order to identify such neuron-responsive astrocyte genes in vitro, we sought to establish an expedited technique for separation of neurons from co-cultured astrocytes. Our newly established method makes use of cold jet, which exploits different adhesion characteristics of subpopulations of cells (Jirsova etal., 1997), and is rapid, performed under ice-cold conditions and avoids protease-mediated isolation of astrocytes or time-consuming centrifugation, yielding intact astrocyte mRNA with approximately 90% of neuronal RNA removed. Using this purification method, we executed genome-wide profiling in which RNA derived from astrocyte-only cultures was compared with astrocyte RNA derived from differentiating neuron-astrocyte co-cultures. Data analysis determined that many astrocytic mRNAs and biological processes are regulated by neuronal interaction. Our results validate the cold jet as an efficient method to separate astrocytes from neurons in co-culture, and reveals that neurons induce robust gene-expression changes in co-cultured astrocytes.

Polymorphisms in the SCD1 gene are associated with indices of stearoyl CoA desaturase activity and obesity: a prospective study

SCOPE

The serum fatty acid (FA) composition is influenced by dietary fat and the endogenous production of FAs. Stearoyl CoA desaturase 1 (SCD1) is the rate-limiting enzyme catalyzing the synthesis of MUFAs from saturated FAs. Variations in SCD1 activity have been associated with obesity, diabetes, or inflammation. We evaluated the associations between genetic variation of the SCD1 gene, SCD1 activity, intake of oil, and obesity in a population-based prospective study in southern Spain.

METHODS AND RESULTS

We collected phenotypic, metabolic, nutritional, and genetic information. The type of dietary fat was assessed from samples of cooking oil taken from the participants' kitchens and analyzed by GC. A total of nine single nucleotide polymorphisms (SNPs) of the SCD1 gene were analyzed by SNPlex technology. We found a significant association between SCD1 genetic variation and enzyme activity in four of nine polymorphisms studied. An interaction between rs10883463 and olive oil intake on the [18:1/18:0] desaturase index was found (p = 0.009). We also showed that genetic variations in the SCD1 gene were associated with obesity.

CONCLUSION

Our results show a relationship between genetic variation of the SCD1 gene, enzyme activity, and the risk of obesity, an association that is not independent of the type of oil consumed.

Astrocytes shed large membrane vesicles that contain mitochondria, lipid droplets and ATP

Various cells types, including stem and progenitor cells, can exchange complex information via plasma membrane-derived vesicles, which can carry signals both in their limiting membrane and lumen. Astrocytes, traditionally regarded as mere supportive cells, play previously unrecognized functions in neuronal modulation and are capable of releasing signalling molecules of different functional significance. In the present study, we provide direct evidence that human fetal astrocytes in culture, expressing the same feature as immature and reactive astrocytes, release membrane vesicles larger than the microvesicles described up to now. We found that these large vesicles, ranging from 1-5 to 8 μm in diameter and expressing on their surface β1-integrin proteins, contain mitochondria and lipid droplets together with ATP. We documented vesicle content with fluorescent-specific dyes and with the immunocytochemistry technique we confirmed that mitochondria and lipid droplets were co-localized in the same vesicle. Scanning electron microscopy and transmission electron microscopy confirmed that astrocytes shed from surface membrane vesicles of the same size as the ones detected by fluorescence microscopy. Our results report for the first time that cultured astrocytes, activated by repetitive stimulation of ATP released from neighboring cells, shed from their surface large membrane vesicles containing mitochondria and lipid droplets.

Therapeutic use of omega-3 fatty acids in bipolar disorder

Bipolar disorder (BD) is a severe, chronic affective disorder, associated with significant disability, morbidity and premature mortality. Omega-3 polyunsaturated fatty acids (PUFAs) play several important roles in brain development and functioning. Evidence from animal models of dietary omega-3 (n-3) PUFA deficiency suggest that these fatty acids are relevant to promote brain development and to regulate behavioral and neurochemical aspects related to mood disorders, such as stress responses, depression and aggression, as well as dopaminergic content and function. Preclinical and clinical evidence suggests roles for PUFAs in BD. n-3 PUFAs seem to be an effective adjunctive treatment for unipolar and bipolar depression, but further large-scale, well-controlled trials are needed to examine its clinical utility in BD. The use of n-3 as a mood stabilizer among BD patients is discussed here. This article summarizes the molecular pathways related to the role of n-3 as a neuroprotective and neurogenic agent, with a specific focus on BDNF. It is proposed that the n-3-BDNF association is involved in the pathophysiology of BD and represents a promising target for developing a novel class of rationally devised therapies.

Reduced expression of fatty acid biosynthesis genes in the prefrontal cortex of patients with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is associated with central and peripheral deficits in long-chain polyunsaturated fatty acids (LC-PUFA), particularly those in the omega-3 fatty acid family. However, the etiology of these deficits remains poorly understood, and there is currently little known about the expression of genes that mediate fatty acid biosynthesis in MDD patients.

METHODS

The expression of FADS1 (Δ5 desaturase), FADS2 (Δ6 desaturase), HELO1 [ELOVL5] (elongase), PEX19 (peroxisome), and SCD (stearoyl-CoA desaturase [Δ9 desaturase]) was determined in the postmortem prefrontal cortex of MDD patients (n=10) and non-psychiatric controls (n=10) by real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

After correcting for multiple comparisons, FADS1 mRNA expression was significantly lower in MDD patients relative to controls (-27%, p=0.009), and there were trends for lower expression of FADS2 (-30%, p=0.07), HELO1 (-37%, p=0.02), and SCD (-43%, p=0.02). PEX19 mRNA expression did not differ between controls and MDD patients (-2%, p=0.92). There were no significant gender effects, and relative reductions in FADS1, HELO1, and SCD expression were greater in patients that did not commit suicide compared with patients that did commit suicide.

LIMITATIONS

The sample size was small, and all MDD patients were receiving antidepressant medications.

CONCLUSIONS

Principal genes involved in LC-PUFA and monounsaturated fatty acid biosynthesis are down-regulated in the postmortem prefrontal cortex of MDD patients. Additional studies are needed to replicate and extend these findings in a larger sample that includes antidepressant-free MDD patients.

Omega-3 polyunsaturated fatty acids increase the neurite outgrowth of rat sensory neurones throughout development and in aged animals

Polyunsaturated fatty acids (PUFA) of the omega-3 series and omega-6 series modulate neurite outgrowth in immature neurones. However, it has not been determined if their neurotrophic effects persist in adult and aged tissue. We prepared cultures of primary sensory neurones from male and female rat dorsal root ganglia (DRG), isolated at different ages: post-natal day 3 (P3) and day 9 (P9), adult (2-4 months) and aged (18-20 months). Cultures were incubated with the omega-6 PUFA arachidonic acid (AA) and the omega-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), at 0.8, 4, 8 and 40muM. PUFA increased neurite outgrowth throughout the developmental stages studied. The effects of omega-3 PUFA, in particular DHA, were still prominent in aged tissue. The amplitude of the effects was comparable to that of nerve growth factor (NGF; 50ng/ml) and all-trans-retinoic acid (ATRA; 0.1muM). The effects of PUFA were similar in cells positive or negative for the N52 neurofilament marker. Our results show that omega-3 PUFA have a marked neurite-promoting potential in neurones from adult and aged animals.

Imaging and organelle distribution of fluorescent InGaP/ZnS nanoparticles in glial cells

Aim: To assess the effects of oleic acid treatment on subcellular distribution of indium gallium phosphide–zinc sulfide (InGaP/ZnS) nanoparticles in microglia and astrocytes. Materials & methods: The extent of colocalization between the nanoparticles and organelles was assessed by confocal microscopy, spectrofluorometry and cell sorting. Results: Cell treatment with a common fatty acid (oleic acid) within the range of physiological concentrations markedly enhanced the InGaP/ZnS uptake by microglia and afforded their colocalization within lipid droplets/lysosomes but not with mitochondria. Conclusion: These results suggest that the availability of mono-unsaturated fatty acids, such as oleic acid, in different cells could significantly alter nanoparticle uptake and localization, which can in turn affect the functions of cells and tissues coexposed to nanoparticles.

Peroxisome proliferator-activated receptor-alpha is required for the neurotrophic effect of oleic acid in neurons

Oleic acid synthesized by astrocytes behaves as a neurotrophic factor for neurons, up-regulating the molecular markers of axonal and dendritic outgrowth, growth-associated protein 43 and microtubule-associated protein 2. In this work, the nature of the receptor involved in this neurotrophic effect was investigated. As oleic acid has been reported to be a ligand and activator of the peroxisome proliferator-activated receptor (PPAR), we focus on this family of receptors. Our results show that PPARalpha, beta/delta, and gamma are expressed in neurons in culture. However, only the agonists of PPARalpha, Wy14643, GW7647 and oleoylethanolamide, promoted neuronal differentiation, while PPAR beta/delta and gamma agonists did not modify neuronal differentiation. Consequently, we investigated the involvement of PPARalpha (Nr1c1) in oleic acid-induced neuronal differentiation. Our results indicate that oleic acid activates PPARalpha in neurons. In addition, the effect of oleic acid on neuronal morphology, growth-associated protein 43 and microtubule-associated protein 2 expression decreases in neurons after PPARalpha has been silenced by small interfering RNA. Taken together, our results suggest that PPARalpha could be the receptor for oleic acid in neurons, further broadening the range of functions attributed to this family of transcription factors. Although several works have reported that PPARalpha could be involved in neuroprotection, the present work provides the first evidence suggesting a role of PPARalpha in neuronal differentiation.

Genome-wide computational prediction of transcriptional regulatory modules reveals new insights into human gene expression

The identification of regulatory regions is one of the most important and challenging problems toward the functional annotation of the human genome. In higher eukaryotes, transcription-factor (TF) binding sites are often organized in clusters called cis-regulatory modules (CRM). While the prediction of individual TF-binding sites is a notoriously difficult problem, CRM prediction has proven to be somewhat more reliable. Starting from a set of predicted binding sites for more than 200 TF families documented in Transfac, we describe an algorithm relying on the principle that CRMs generally contain several phylogenetically conserved binding sites for a few different TFs. The method allows the prediction of more than 118,000 CRMs within the human genome. A subset of these is shown to be bound in vivo by TFs using ChIP-chip. Their analysis reveals, among other things, that CRM density varies widely across the genome, with CRM-rich regions often being located near genes encoding transcription factors involved in development. Predicted CRMs show a surprising enrichment near the 3' end of genes and in regions far from genes. We document the tendency for certain TFs to bind modules located in specific regions with respect to their target genes and identify TFs likely to be involved in tissue-specific regulation. The set of predicted CRMs, which is made available as a public database called PReMod (http://genomequebec.mcgill.ca/PReMod), will help analyze regulatory mechanisms in specific biological systems.

Regulation of stearoyl-CoA desaturase expression

Stearoyl-CoA desaturase (SCD) is a regulatory enzyme in lipogenesis, catalyzing the rate-limiting step in the overall de novo synthesis of monounsaturated FA, mainly oleate and palmitoleate from stearoyl- and palmitoyl-CoA, respectively. Oleate and palmitoleate are the major monounsaturated FA of membrane phospholipids, TG, wax esters, cholesterol esters, and alkyldiacylglycerol. Several SCD gene isoforms (SCD1, SCD2, SCD3, and SCD4) exist in mice, and two have been characterized in humans. SCD1 gene expression in liver cells is regulated by numerous stimuli including diet and hormones. We are interested in why SCD is such a highly regulated enzyme even though oleate, the major product of this enzyme, is one of the most abundant FA in the diet and is therefore readily available. Dietary oleate is also well known for its TG-lowering effects and, as a major component of olive oil, is expected to have beneficial effects. However, high SCD activity has been implicated in diabetes, obesity, atherosclerosis, and cancer in several animal models; therefore, the role that de novo oleate plays in these disease states has to be carefully evaluated. By using SCD1-/- mice, which are deficient in tissue oleate, we begin to learn more about the physiological role of SCD gene expression and oleate in normal and disease states.

Cellular mitochondrial heterogeneity in cultured astrocytes as demonstrated by immunogold labeling of α-ketoglutarate dehydrogenase

In brain cells, various metabolites and metabolic pathways, largely of mitochondrial origin, have been shown to be compartmentalized. Attention has therefore been focused on the possible existence of mitochondrial heterogeneity in the brain at the cellular level. To determine whether mitochondria in cultured cortical and cerebellar astrocytes are heterogeneous at the single cell level, immunogold electron microscopy and an antibody against the alpha-ketoglutarate dehydrogenase component of the alpha-ketoglutarate dehydrogenase complex, a marker enzyme for the tricarboxylic acid (TCA) cycle, were employed. The number of gold particles was counted in the mitochondria of 36 and 42 cells from cultured cerebellar and cortical astrocytes, respectively. A test for random distribution (Poisson distribution) of mitochondria according to the number of gold particles was subsequently performed for every one of the 36 and 42 cells as the ratio variance/mean (= index of dispersion). This should be approximately distributed as chi2/degrees of freedom (df) = n - 1, n = number of mitochondria), if the observations obeyed a Poisson distribution. For 26 of the 36 (cerebellar astrocytes) distributions and for 28 of the 42 (cortical astrocytes) distributions a random distribution had to be rejected. These findings therefore strongly indicate that alpha-ketoglutarate dehydrogenase is heterogeneously distributed in mitochondria within individual astrocytes originating either from cerebellum or cerebral cortex. In conclusion, this study underlines the probability that mitochondrial heterogeneity at the single cell level might be extended to involve other metabolic pathways and metabolites.

Long-chain fatty acids increase cellular dopamine in an immortalized cell line (MN9D) derived from mouse mesencephalon

The lysate of an immortalized monoclonal cell line derived from the striatum (X61) contains a dopaminergic stimulatory activity that is capable of increasing the dopamine content of an immortalized mouse mesencephalic cell line (MN9D) which expresses a dopaminergic phenotype. Purification of an isoamyl alcohol extract of this lysate and subsequent identification by NMR spectroscopic analysis demonstrated that the dopaminergic stimulatory activity contained within the lysate was a mixture of 80-90% cis-9-octadecenoic acid (oleic acid) and 10-20% cis-11-octadecenoic acid (cis-vaccenic acid). The effect of oleic acid on MN9D dopamine is a prolonged event. MN9D dopamine increases linearly over a 48 h period suggesting the induction of an increased dopaminergic phenotype in these dividing cells. The ability to increase MN9D dopamine by oleic and cis-vaccenic acids is shared by a number of other long-chain fatty acids including arachidonic, linoleic, linolenic, palmitoleic, and cis-13-octadecenoic acid. The possibility that oleic or other relatively innocuous fatty acids might affect dopaminergic function in primary neurons is intriguing with respect to possible therapeutic approaches to the treatment of dopaminergic cell loss and the motor sequelae of Parkinson's disease.

Regulation of stearoyl-CoA desaturase-1 after central and peripheral nerve lesions

Background

Interruption of mature axons activates a cascade of events in neuronal cell bodies which leads to various outcomes from functional regeneration in the PNS to the failure of any significant regeneration in the CNS. One factor which seems to play an important role in the molecular programs after axotomy is the stearoyl Coenzyme A-desaturase-1 (SCD-1). This enzyme is needed for the conversion of stearate into oleate. Beside its role in membrane synthesis, oleate could act as a neurotrophic factor, involved in signal transduction pathways via activation of protein kinases C.

Results

In situ hybridization and immunohistochemistry demonstrated a strong up-regulation of SCD at mRNA and protein level in regenerating neurons of the rat facial nucleus whereas non-regenerating Clarke's and Red nucleus neurons did not show an induction of this gene.

Conclusion

This differential expression points to a functionally significant role for the SCD-1 in the process of regeneration.

Stearoyl-CoA desaturase 1 gene expression is necessary for fructose-mediated induction of lipogenic gene expression by sterol regulatory element-binding protein-1c-dependent and -independent mechanisms

Stearoyl-CoA desaturase (SCD) synthesizes oleate necessary for the biosynthesis of triglycerides and other lipids. Mice with a targeted disruption of the SCD1 gene are deficient in tissue oleate and have reduced expression of the sterol regulatory element-binding protein (SREBP) and its target genes. The SREBP-1c isoform is a known mediator of insulin action on hepatic gene expression, but its transcriptional effects due to glucose or fructose are still unclear. We found that fructose compared with glucose is a stronger inducer of SREBP-1c and lipogenic gene expression, causing a dramatic increase in hepatic triglyceride levels. However, when fed to the SCD1-/- mice, fructose failed to induce SREBP-1 or lipogenic genes and the triglyceride levels were not increased. Instead fructose feeding caused a decrease in hepatic glycogen and plasma glucose levels. The induction of SREBP-1 and lipogenic gene expression as well as the levels of liver triglycerides, glycogen, and plasma glucose was partially restored when the fructose diet was supplemented with very high levels of oleate (20% by weight) but not with palmitate, stearate, or linoleate. Fructose in a long term feeding induced the expression of SCD1 and that of other lipogenic genes in the liver of SREBP-1c-/- mice, and a further increase in expression of these genes occurred when the fructose diet was supplemented with oleate. Our observations demonstrated that oleate produced by SCD is necessary for fructose-mediated induction of lipogenic gene expression through SREBP-1c-dependent and -independent mechanisms and suggested that SCD1 gene expression is important in lipid and carbohydrate homeostasis.

The neurotrophic effect of oleic acid includes dendritic differentiation and the expression of the neuronal basic helix-loop-helix transcription factor NeuroD2

We have shown recently that the presence of albumin in astrocytes triggers the synthesis and release of oleic acid, which behaves as a neurotrophic factor for neurons. Thus, oleic acid promotes axonal growth together with the expression of the axonal growth-associated protein, GAP-43. Here we attempted to elucidate whether the neurotrophic effect of oleic acid includes dendritic differentiation. Our results indicate that oleic acid induces the expression of microtubule associated protein-2 (MAP-2), a marker of dendritic differentiation. In addition, the presence of oleic acid promotes the translocation of MAP-2 from the soma to the dendrites. The time course of MAP-2 expression during brain development coincides with that of stearoyl-CoA desaturase, the limiting enzyme of oleic acid synthesis, indicating that both phenomena coincide during development. The effect of oleic acid on MAP-2 expression is most probably independent of autocrine factors synthesized by neurons because this effect was also observed at low cellular densities. As oleic acid is an activator of protein kinase C, the possible participation of this transduction pathway was studied. Our results indicate that added oleic acid or oleic acid endogenously synthesized by astrocytes exerts its neurotrophic effect through a protein kinase C-dependent mechanism as the effect was inhibited by sphingosine or two myristoylated peptide inhibitors of protein kinase C. The transduction pathway by which oleic acid induces the expression of genes responsible for neuronal differentiation appears to be mediated by the transcription factor NeuroD2, a regulator of terminal neuronal differentiation.