Transgenic mice with high endogenous omega-3 fatty acids are protected from spinal cord injury

Mechanism Underlying Acupuncture Therapy in Spinal Cord Injury: A Narrative Overview of Preclinical Studies

Spinal cord injury (SCI) results from various pathogenic factors that destroy the normal structure and function of the spinal cord, subsequently causing sensory, motor, and autonomic nerve dysfunction. SCI is one of the most common causes of disability and death globally. It leads to severe physical and mental injury to patients and causes a substantial economic burden on families and the society. The pathological changes and underlying mechanisms within SCI involve oxidative stress, apoptosis, inflammation, etc. As a traditional therapy, acupuncture has a positive effect promoting the recovery of SCI. Acupuncture-induced neuroprotection includes several mechanisms such as reducing oxidative stress, inhibiting the inflammatory response and neuronal apoptosis, alleviating glial scar formation, promoting neural stem cell differentiation, and improving microcirculation within the injured area. Therefore, the recent studies exploring the mechanism of acupuncture therapy in SCI will help provide a theoretical basis for applying acupuncture and seeking a better treatment target and acupuncture approach for SCI patients.

Regulation of Inflammasomes by Application of Omega-3 Polyunsaturated Fatty Acids in a Spinal Cord Injury Model

Omega-3 polyunsaturated fatty acids (PUFA n3) ameliorate inflammation in different diseases and potentially improve neurological function after neuronal injury. Following spinal cord injury (SCI), inflammatory events result in caspase-1 mediated activation of interleukin-1 beta (IL-1b) and 18. We aim to evaluate the neuroprotective potency of PUFA n3 in suppressing the formation and activation of inflammasomes following SCI. Male Wistar rats were divided into four groups: control, SCI, SCI+PUFA n3, and SCI+Lipofundin MCT (medium-chain triglyceride; vehicle). PUFA n3 or vehicle was intravenously administered immediately after SCI and every 24 h for the next three days. We analyzed the expression of NLRP3, NLRP1, ASC, caspase-1, IL-1b, and 18 in the spinal cord. The distribution of microglia, oligodendrocytes, and astrocytes was assessed by immunohistochemistry analysis. Behavioral testing showed significantly improved locomotor recovery in PUFA n3-treated animals and the SCI-induced upregulation of inflammasome components was reduced. Histopathological evaluation confirmed the suppression of microgliosis, increased numbers of oligodendrocytes, and the prevention of demyelination by PUFA n3. Our data support the neuroprotective role of PUFA n3 by targeting the NLRP3 inflammasome. These findings provide evidence that PUFA n3 has therapeutic effects which potentially attenuate neuronal damage in SCI and possibly also in other neuronal injuries.

Nutritional interventions for spinal cord injury: preclinical efficacy and molecular mechanisms

Spinal cord injury (SCI) is a debilitating condition that leads to motor, sensory, and autonomic impairments. Its intrinsic pathophysiological complexity has hindered the establishment of effective treatments for decades. Nutritional interventions (NIs) for SCI have been proposed as a route to circumvent some of the problems associated with this condition. Results obtained in animal models point to a more holistic effect, rather than to specific modulation, of several relevant SCI pathophysiological processes. Indeed, published data have shown NI improves energetic imbalance, oxidative damage, and inflammation, which are promoters of improved proteostasis and neurotrophic signaling, leading ultimately to neuroprotection and neuroplasticity. This review focuses on the most well-documented Nis. The mechanistic implications and their translational potential for SCI are discussed.

Bioactive Lipid Mediators in the Initiation and Resolution of Inflammation after Spinal Cord Injury

Neuroinflammation is a prominent feature of the response to CNS trauma. It is also an important hallmark of various neurodegenerative diseases in which inflammation contributes to the progression of pathology. Inflammation in the CNS can contribute to secondary damage and is therefore an excellent therapeutic target for a range of neurological conditions. Inflammation in the nervous system is complex and varies in its fine details in different conditions. It involves a wide variety of secreted factors such as chemokines and cytokines, cell adhesion molecules, and different cell types that include resident cell of the CNS, as well as immune cells recruited from the peripheral circulation. Added to this complexity is the fact that some aspects of inflammation are beneficial, while other aspects can induce secondary damage in the acute, subacute and chronic phases. Understanding these aspects of the inflammatory profile is essential for developing effective therapies. Bioactive lipids constitute a large group of molecules that modulate the initiation and the resolution of inflammation. Dysregulation of these bioactive lipid pathways can lead to excessive acute inflammation, and failure to resolve this by specialized pro-resolution lipid mediators can lead to the development of chronic inflammation. The focus of this review is to discuss the effects of bioactive lipids in spinal cord trauma and their potential for therapies.

Significance of Omega-3 Fatty Acids in the Prophylaxis and Treatment after Spinal Cord Injury in Rodent Models

Polyunsaturated fatty acids (ω-3 acids, PUFAs) are essential components of cell membranes in all mammals. A multifactorial beneficial influence of ω-3 fatty acids on the health of humans and other mammals has been observed for many years. Therefore, ω-3 fatty acids and their function in the prophylaxis and treatment of various pathologies have been subjected to numerous studies. Regarding the documented therapeutic influence of ω-3 fatty acids on the nervous and immune systems, the aim of this paper is to present the current state of knowledge and the critical assessment of the role of ω-3 fatty acids in the prophylaxis and treatment of spinal cord injury (SCI) in rodent models. The prophylactic properties (pre-SCI) include the stabilization of neuron cell membranes, the reduction of the expression of inflammatory cytokines (IL-1β, TNF-α, IL-6, and KC/GRO/CINC), the improvement of local blood flow, reduced eicosanoid production, activation of protective intracellular transcription pathways (dependent on RXR, PPAR-α, Akt, and CREB), and increased concentration of lipids, glycogen, and oligosaccharides by neurons. On the other hand, the therapeutic properties (post-SCI) include the increased production of endogenous antioxidants such as carnosine and homocarnosine, the maintenance of elevated GSH concentrations at the site of injury, reduced concentrations of oxidative stress marker (MDA), autophagy improvement (via increasing the expression of LC3-II), and p38 MAPK expression reduction in the superficial dorsal horns (limiting the sensation of neuropathic pain). Paradoxically, despite the well-documented protective activity of ω-3 acids in rodents with SCI, the research does not offer an answer to the principal question of the optimal dose and treatment duration. Therefore, it is worth emphasizing the role of multicenter rodent studies with the implementation of standards which initially may even be based on arbitrary criteria. Additionally, basing on available research data, the authors of this paper make a careful attempt at referring some of the conclusions to the human population.

Docosahexaenoic acid reduces microglia phagocytic activity via miR-124 and induces neuroprotection in rodent models of spinal cord contusion injury

Microglia are activated after spinal cord injury (SCI), but their phagocytic mechanisms and link to neuroprotection remain incompletely characterized. Docosahexaenoic acid (DHA) has been shown to have significant neuroprotective effects after hemisection and compression SCI and can directly affect microglia in these injury models. In rodent contusion SCI, we demonstrate that DHA (500 nmol/kg) administered acutely post-injury confers neuroprotection and enhances locomotor recovery, and also exerts a complex modulation of the microglial response to injury. In rodents, at 7 days after SCI, the level of phagocytosed myelin within Iba1-positive or P2Y12-positive cells was significantly lower after DHA treatment, and this occurred in parallel with an increase in intracellular miR-124 expression. Furthermore, intraspinal administration of a miR-124 inhibitor significantly reduced the DHA-induced decrease in myelin phagocytosis in mice at 7 days post-SCI. In rat spinal primary microglia cultures, DHA reduced the phagocytic response to myelin, which was associated with an increase in miR-124, but not miR-155. A similar response was observed in a microglia cell line (BV2) treated with DHA, and the effect was blocked by a miR-124 inhibitor. Furthermore, the phagocytic response of BV2 cells to stressed neurones was also reduced in the presence of DHA. In peripheral monocyte-derived macrophages, the expression of the M1, but not the M0 or M2 phenotype, was reduced by DHA, but the phagocytic activation was not altered. These findings show that DHA induces neuroprotection in contusion injury. Furthermore, the improved outcome is via a miR-124-dependent reduction in the phagocytic response of microglia.

Quantification of surviving neurons after contusion, dislocation, and distraction spinal cord injuries using automated methods

This study proposes and validates an automated method for counting neurons in spinal cord injury (SCI) and then uses it to examine and compare the surviving cells in common types of SCI mechanisms. Moderate contusion, dislocation, and distraction SCIs were surgically induced in Sprague Dawley male rats (n = 6 for each type of injury). Their spinal cords were harvested 8 weeks post injury with 5 normal weight-matched rats. The spinal cords were cut, stained with anti-NeuN antibody and fluorescent Nissl, and imaged in the dorsal and ventral horns at various distances to the epicenter. Neurons in the images were automatically counted using an algorithm that was designed to filter non-soma-like objects based on morphological characteristics (size, solidity, circular pattern) and check the remaining objects for the double-stained nucleus/cell body features (brightness variation, brightness distribution, color). To validate the automated method, some of the images were randomly selected for manual counting. The number of surviving cells that were automatically measured by the algorithm was found to be correlated with the values that were manually measured by 2 observers (P < .001) with similar differences (P > .05). Neurons in the dorsal and ventral horns were reduced after the SCIs (P < .05). Dislocation and distraction, respectively, caused the most severe damage to the ventral horn neurons especially near the epicenter and the most extensive and uniform damage to the dorsal horn neurons (P < .05). Our method was proved to be reliable, which is suitable for studying different types of SCI.

Effects of FABP7 on functional recovery after spinal cord injury in adult mice

OBJECTIVE

Elucidating the mechanisms of neuronal injury is crucial for the development of spinal cord injury (SCI) treatments. Brain-type fatty acid-binding protein 7 (FABP7) is expressed in the adult rodent brain, especially in astrocytes, and has been reported to play a role in astrocyte function in various types of brain damage; however, its role after SCI has not been well studied. In this study, the authors evaluated the expression change of FABP7 after SCI using a mouse spinal cord compression model and observed the effect of FABP7 gene knockout on neuronal damage and functional recovery after SCI.

METHODS

Female FABP7 knockout (KO) mice with a C57BL/6 background and their respective wild-type littermates were subjected to SCI with a vascular clip. The expression of FABP7, neuronal injury, and functional recovery after SCI were analyzed in both groups of mice.

RESULTS

Western blot analysis revealed upregulation of FABP7 in the wild-type mice, which reached its peak 14 days after SCI, with a significant difference in comparison to the control mice. Immunohistochemistry also showed upregulation of FABP7 at the same time points, mainly in proliferative astrocytes. The number of surviving ventral neurons in the FABP7-KO mice at 28 days after SCI was significantly lower than that observed in the wild-type mice. In addition, motor functional recovery in the FABP7-KO mice was significantly worse than that of the wild-type mice.

CONCLUSIONS

The findings of this study indicate that FABP7 could have a neuroprotective role that might be associated with modulation of astrocytes after SCI. FABP7 could potentially be a therapeutic target in the treatment of SCI.

Energy balance following diets of varying fat content: metabolic dysregulation in a rodent model of spinal cord contusion

Within the spinal cord injured (SCI) population, metabolic dysfunction may be exacerbated. Models of cord injury coupled with metabolic stressors have translational relevance to understand disease progression in this population. In the present study, we used a rat model of thoracic SCI at level T10 (tSCI) and administered diets comprised of either 9% or 40% butterfat to create a unique model system to understand the physiology of weight regulation following cord injury. SCI rats that recovered on chow for 28 days had reduced body mass, lean mass, and reduced fat mass but no differences in percentage of lean or fat mass composition. Following 12 weeks on either low-fat diet (LFD) or high-fat diet (HFD), SCI rats maintained on LFD did not gain weight at the same rate as SCI animals maintained on HFD. LFD-SCI had reduced feed conversion efficiency in comparison to Sham-LFD whereas tSCI-HFD were equivalent to Sham-HFD rats. Although SCI rats still maintained lower lean body mass, by the end of the study HFD-fed rats had higher body fat percentage than LFD-fed rats. Macronutrient selection testing demonstrated SCI rats had a significant preference for protein over Sham rats. Analysis of metabolic cage activity showed tSCI rats had elevated energy expenditure, despite reduced locomotor activity. Muscle triglycerides and cholesterol were reduced only in LFD-tSCI rats. These data suggest that consumption of HFD by tSCI rats alters the trajectory of metabolic dysfunction in the context of spinal cord disease progression.

Bioactive Lipids in Inflammation After Central Nervous System Injury

Despite the progress made over the last decades to understand the mechanisms underlying tissue damage and neurological deficits after neurotrauma, there are currently no effective treatments in the clinic. It is well accepted that the inflammatory response in the CNS after injury exacerbates tissue loss and functional impairments. Unfortunately, the use of potent anti-inflammatory drugs, such as methylprednisolone, fails to promote therapeutic recovery and also gives rise to several undesirable side effects related to immunosuppression. The injury-induced inflammatory response is complex, and understanding the mechanisms that regulate this inflammation is therefore crucial in the quest to develop effective treatments. Bioactive lipids have emerged as potent molecules in controlling the initiation, coordination, and resolution of inflammation and in promoting tissue repair and recovery of homeostasis. These bioactive lipids are produced by cells involved in the inflammatory response, and their defective synthesis leads to persistent chronic inflammation, tissue damage, and fibrosis. The present chapter discusses recent evidence for the role of some of these bioactive lipids, in particular, eicosanoid and pro-resolving lipid mediators, in the regulation of inflammation after neurotrauma and highlights the therapeutic potential of some of these lipids in enhancing neurological outcomes after CNS injuries.

Hypothermic treatment after computer-controlled compression in minipig: A preliminary report on the effect of epidural vs. direct spinal cord cooling

The aim of the present study was to investigate the therapeutic efficacy of local hypothermia (beginning 30 min post-injury persisting for 5 h) on tissue preservation along the rostro-caudal axis of the spinal cord (3 cm cranially and caudally from the lesion site), and the prevention of injury-induced functional loss in a newly developed computer-controlled compression model in minipig (force of impact 18N at L3 level), which mimics severe spinal cord injury (SCI). Minipigs underwent SCI with two post-injury modifications (durotomy vs. intact dura mater) followed by hypothermia through a perfusion chamber with cold (epidural t≈15°C) saline, DMEM/F12 or enriched DMEM/F12 (SCI/durotomy group) and with room temperature (t≈24°C) saline (SCI-only group). Minipigs treated with post-SCI durotomy demonstrated slower development of spontaneous neurological improvement at the early postinjury time points, although the outcome at 9 weeks of survival did not differ significantly between the two SCI groups. Hypothermia with saline (t≈15°C) applied after SCI-durotomy improved white matter integrity in the dorsal and lateral columns in almost all rostro-caudal segments, whereas treatment with medium/enriched medium affected white matter integrity only in the rostral segments. Furthermore, regeneration of neurofilaments in the spinal cord after SCI-durotomy and hypothermic treatments indicated an important role of local saline hypothermia in the functional outcome. Although saline hypothermia (24°C) in the SCI-only group exhibited a profound histological outcome (regarding the gray and white matter integrity and the number of motoneurons) and neurofilament protection in general, none of the tested treatments resulted in significant improvement of neurological status. The findings suggest that clinically-proven medical treatments for SCI combined with early 5 h-long saline hypothermia treatment without opening the dural sac could be more beneficial for tissue preservation and neurological outcome compared with hypothermia applied after durotomy.

Docosahexaenoic acid (DHA): An essential nutrient and a nutraceutical for brain health and diseases

Docosahexaenoic acid (DHA), a polyunsaturated fatty acid (PUFA) enriched in phospholipids in the brain and retina, is known to play multi-functional roles in brain health and diseases. While arachidonic acid (AA) is released from membrane phospholipids by cytosolic phospholipase A2 (cPLA2), DHA is linked to action of the Ca2+-independent iPLA2. DHA undergoes enzymatic conversion by 15-lipoxygenase (Alox 15) to form oxylipins including resolvins and neuroprotectins, which are powerful lipid mediators. DHA can also undergo non-enzymatic conversion by reacting with oxygen free radicals (ROS), which cause the production of 4-hydoxyhexenal (4-HHE), an aldehyde derivative which can form adducts with DNA, proteins and lipids. In studies with both animal models and humans, there is evidence that inadequate intake of maternal n-3 PUFA may lead to aberrant development and function of the central nervous system (CNS). What is less certain is whether consumption of n-3 PUFA is important in maintaining brain health throughout one's life span. Evidence mostly from non-human studies suggests that DHA intake above normal nutritional requirements might modify the risk/course of a number of diseases of the brain. This concept has fueled much of the present interest in DHA research, in particular, in attempts to delineate mechanisms whereby DHA may serve as a nutraceutical and confer neuroprotective effects. Current studies have revealed ability for the oxylipins to regulation of cell redox homeostasis through the Nuclear factor (erythroid-derived 2)-like 2/Antioxidant response element (Nrf2/ARE) anti-oxidant pathway, and impact signaling pathways associated with neurotransmitters, and modulation of neuronal functions involving brain-derived neurotropic factor (BDNF). This review is aimed at describing recent studies elaborating these mechanisms with special regard to aging and Alzheimer's disease, autism spectrum disorder, schizophrenia, traumatic brain injury, and stroke.

Inhibition of mammalian target of rapamycin complex 1 signaling by n-3 polyunsaturated fatty acids promotes locomotor recovery after spinal cord injury

The present study aimed to explore the effects of n‑3 polyunsaturated fatty acids (PUFAs) on autophagy and their potential for promoting locomotor recovery after spinal cord injury (SCI). Primary neurons were isolated and cultured. Sprague‑Dawley rats were randomly divided into three groups and fed diets with different amounts of n‑3 PUFAs. A model of spinal cord contusion was created at the T10 spinal segment and the composition of PUFAs was analyzed using gas chromatography. Spinal repair and motor function were evaluated postoperatively. Assessment of the effects of n‑3 PUFAs on autophagy and mammalian target of rapamycin complex 1 (mTORC1) was performed using immunofluorescence staining and western blotting. In vitro, n‑3 PUFAs inhibited mTORC1 and enhanced autophagy. The n‑3 PUFA levels and the ratio of n‑3 PUFA to n‑6 PUFA in the spinal cord and serum of rats fed a high‑n‑3 PUFA diet were higher before and after operation (P<0.05). Additionally, rats in the high‑n‑3 PUFA group showed improved motor function recovery, spinal cord repair‑related protein expression level (MBP, Galc and GFAP). Expression levels if these protiens in the high‑n‑3 PUFA diet group expressed the highest levels, followed by the low‑n‑3 PUFA diet group and finally the control group (P<0.05). high‑n‑3 PUFA diet promoted autophagy ability and inhibited activity of the mTORC1 signaling pathway compared with the low‑n‑3 PUFA diet group or the control group (P<0.05). These results suggest that exogenous dietary n‑3 PUFAs can inhibit mTORC1 signaling and enhance autophagy, promoting functional recovery of rats with SCI.

Anti-Inflammatory Effects of Omega-3 Fatty Acids in the Brain: Physiological Mechanisms and Relevance to Pharmacology

Classically, polyunsaturated fatty acids (PUFA) were largely thought to be relatively inert structural components of brain, largely important for the formation of cellular membranes. Over the past 10 years, a host of bioactive lipid mediators that are enzymatically derived from arachidonic acid, the main n-6 PUFA, and docosahexaenoic acid, the main n-3 PUFA in the brain, known to regulate peripheral immune function, have been detected in the brain and shown to regulate microglia activation. Recent advances have focused on how PUFA regulate the molecular signaling of microglia, especially in the context of neuroinflammation and behavior. Several active drugs regulate brain lipid signaling and provide proof of concept for targeting the brain. Because brain lipid metabolism relies on a complex integration of diet, peripheral metabolism, including the liver and blood, which supply the brain with PUFAs that can be altered by genetics, sex, and aging, there are many pathways that can be disrupted, leading to altered brain lipid homeostasis. Brain lipid signaling pathways are altered in neurologic disorders and may be viable targets for the development of novel therapeutics. In this study, we discuss in particular how n-3 PUFAs and their metabolites regulate microglia phenotype and function to exert their anti-inflammatory and proresolving activities in the brain.

Interplay Between n-3 and n-6 Long-Chain Polyunsaturated Fatty Acids and the Endocannabinoid System in Brain Protection and Repair

The brain is enriched in arachidonic acid (ARA) and docosahexaenoic acid (DHA), long-chain polyunsaturated fatty acids (LCPUFAs) of the n-6 and n-3 series, respectively. Both are essential for optimal brain development and function. Dietary enrichment with DHA and other long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA), has shown beneficial effects on learning and memory, neuroinflammatory processes, and synaptic plasticity and neurogenesis. ARA, DHA and EPA are precursors to a diverse repertoire of bioactive lipid mediators, including endocannabinoids. The endocannabinoid system comprises cannabinoid receptors, their endogenous ligands, the endocannabinoids, and their biosynthetic and degradation enzymes. Anandamide (AEA) and 2-arachidonoylglycerol (2-AG) are the most widely studied endocannabinoids and are both derived from phospholipid-bound ARA. The endocannabinoid system also has well-established roles in neuroinflammation, synaptic plasticity and neurogenesis, suggesting an overlap in the neuroprotective effects observed with these different classes of lipids. Indeed, growing evidence suggests a complex interplay between n-3 and n-6 LCPUFA and the endocannabinoid system. For example, long-term DHA and EPA supplementation reduces AEA and 2-AG levels, with reciprocal increases in levels of the analogous endocannabinoid-like DHA and EPA-derived molecules. This review summarises current evidence of this interplay and discusses the therapeutic potential for brain protection and repair.

Long-Chain Omega-3 Fatty Acids Supplementation Accelerates Nerve Regeneration and Prevents Neuropathic Pain Behavior in Mice

Fish oil (FO) is the main source of long chain omega-3 polyunsaturated fatty acids (ω-3 PUFAs), which display relevant analgesic and anti-inflammatory properties. Peripheral nerve injury is driven by degeneration, neuroinflammation, and neuronal plasticity which results in neuropathic pain (NP) symptoms such as allodynia and hyperalgesia. We tested the preventive effect of an EPA/DHA-concentrate fish oil (CFO) on NP development and regenerative features. Swiss mice received daily oral treatment with CFO 4.6 or 2.3 g/kg for 10 days after NP was induced by partial sciatic nerve ligation. Mechanical allodynia and thermal hypernociception were assessed 5 days after injury. CFO 2.3 g/kg significantly prevented mechanical and thermal sensitization, reduced TNF levels in the spinal cord, sciatic MPO activity, and ATF-3 expression on DRG cells. CFO improved Sciatic Functional Index (SFI) as well as electrophysiological recordings, corroborating the increased GAP43 expression and total number of myelinated fibers observed in sciatic nerve. No locomotor activity impairment was observed in CFO treated groups. These results point to the regenerative and possibly protective properties of a combined EPA and DHA oral administration after peripheral nerve injury, as well as its anti-neuroinflammatory activity, evidencing ω-3 PUFAs promising therapeutic outcomes for NP treatment.

Balanced Diet-Fed Fat-1 Transgenic Mice Exhibit Lower Hindlimb Suspension-Induced Soleus Muscle Atrophy

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.

Omega-3 Long-Chain Fatty Acids in the Heart, Kidney, Liver and Plasma Metabolite Profiles of Australian Prime Lambs Supplemented with Pelleted Canola and Flaxseed Oils

The objective of the study was to ascertain whether human health beneficial omega-3 long-chain (≥C20) polyunsaturated fatty acid (n-3 LC-PUFA) content in heart, kidney and liver can be enhanced by supplementing prime lambs with graded levels of canola and flaxseed oil. Health status of the lambs, as a consequence of the supplementation, was also investigated by examining their plasma metabolites. Sixty purebred and first-cross lambs were allocated to one of five treatments of lucerne hay basal diet supplemented with isocaloric and isonitrogenous wheat-based pellets without oil inclusion (Control) or graded levels of canola oil at 2.5% (2.5C), 5% (5C), flaxseed oil at 2.5% (2.5F) and 5% (5F) in a completely randomised design. Pre-slaughter blood, post-slaughter kidney, liver and heart samples were analysed for plasma metabolite and fatty acid profiles. Summations of docosapentaenoic acid and docosahexaenoic acid, and total n-3 LC-PUFA were enhanced in the liver and kidney of 5F supplemented lambs with a marked decrease in n-6/n-3 ratio and significant breed differences detected. There were generally no deleterious impacts on animal health status. A combination of 5% oil supplementation and lamb genetics is an effective and strategic management tool for enhancing n-3 LC-PUFA contents of heart, kidney and liver without compromising lamb health.

A new method to evaluate the dose-effect relationship of a TCM formula Gegen Qinlian Decoction: "Focus" mode of integrated biomarkers

It is difficult to accurately evaluate the efficacy of traditional Chinese medicine (TCM), which leads to the uncertainty and complexity of dose-effect analysis. In this study we established the "Focus" mode of biomarkers to characterize the dose-effect relationship of Gegen Qinlian Decoction (GQD), a TCM formula for treating type 2 diabetes mellitus (2-DM). A rat model of 2-DM was established through high fat diet feeding combined with low-dose STZ injection. Rats with 2-DM were administered high, middle or low doses (6.785, 4.071, 1.357 mg·kg^-1·d^-1, respectively) of GQD extract for 60 d. Metformin (300 mg·kg^-1·d^-1) was taken as the positive control. Blood samples were collected to assess serum biochemical indexes and metabolic profiling. After "Focus" analysis, the biochemical index triglycerides (TG) and insulin sensitivity (ISI) were identified as focused integrated biomarkers (FIBs), while arachidonic acid and docosatetraenoic acid were the metabolic FIBs. Dose-effect relationship curves of GQD were built based on these types of FIBs. Furthermore, the two dose-effect relationship curves showed similar trends with the middle dosage displaying the greatest efficacy, suggesting that insulin function and arachidonic acid metabolism played important roles in 2-DM and the responses to GQD. The metabolic FIB docosatetraenoic should be further explored for understanding its involvement in the process of 2-DM occurrence and the treatment. This "Focus" mode provides a novel strategy to evaluate the dose-effect relationship of a TCM. The system and concepts established here may also be applicable for assessing the dose-effect relationships of Western medicines.

Modulation of brain PUFA content in different experimental models of mice

The relative amounts of arachidonic acid (AA) and docosahexaenoic acid (DHA) govern the different functions of the brain. Their brain levels depend on structures considered, on fatty acid dietary supply and the age of animals. To have a better overview of the different models available in the literature we here compared the brain fatty acid composition in various mice models (C57BL/6J, CD1, Fat-1, SAMP8 mice) fed with different n-3 PUFA diets (deficient, balanced, enriched) in adults and aged animals. Our results demonstrated that brain AA and DHA content is 1) structure-dependent; 2) strain-specific; 3) differently affected by dietary approaches when compared to genetic model of PUFA modulation; 4) different in n-3 PUFA deficient aged C57BL6/J when compared to SAMP8 mouse model of aging. From these experiments, we highlight the difficulty to compare results obtained in different mouse models, different strains, different brain regions and different ages.

Plasma circulating cell-free mitochondrial DNA in the assessment of Friedreich's ataxia

Friedreich's ataxia (FRDA) is one of the most devastating childhood onset neurodegenerative disease affecting multiple organs in the course of progression. FRDA is associated with mitochondrial dysfunction due to deficit in a nuclear encoded mitochondrial protein, frataxin. Identification of disease-specific biomarker for monitoring the severity remains to be a challenging topic. This study was aimed to identify whether circulating cell-free nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) in blood plasma can be a potential biomarker for FRDA. Clinical information was assessed using International Cooperative Ataxia Rating Scale and the disease was confirmed using Long-range PCR for GAA repeat expansion within the gene encoding frataxin. The frataxin expression was measured using Western blot. Plasma nDNA and mtDNA levels were quantified by Multiplex real-time PCR. The major observation is that the levels of nDNA found to be increased, whereas mtDNA levels were reduced significantly in the plasma of FRDA patients (n=21) as compared to healthy controls (n=21). Further, plasma mtDNA levels showed high sensitivity (90%) and specificity (76%) in distinguishing from healthy controls with optimal cutoff indicated at 4.1×10(5)GE/mL. Interestingly, a small group of follow-up patients (n=9) on intervention with, a nutrient supplement, omega-3 fatty acid (a known enhancer of mitochondrial metabolism) displayed a significant improvement in the levels of plasma mtDNA, supporting our hypothesis that plasma mtDNA can be a potential monitoring or prognosis biomarker for FRDA.

Increased production of omega-3 fatty acids protects retinal ganglion cells after optic nerve injury in mice

Injury to the central nervous system causes progressive degeneration of injured axons, leading to loss of the neuronal bodies. Neuronal survival after injury is a prerequisite for successful regeneration of injured axons. In this study, we investigated the effects of increased production of omega-3 fatty acids and elevation of cAMP on retinal ganglion cell (RGC) survival and axonal regeneration after optic nerve (ON) crush injury in adult mice. We found that increased production of omega-3 fatty acids in mice enhanced RGC survival, but not axonal regeneration, over a period of 3 weeks after ON injury. cAMP elevation promoted RGC survival in wild type mice, but no significant difference in cell survival was seen in mice over-producing omega-3 fatty acids and receiving intravitreal injections of CPT-cAMP, suggesting that cAMP elevation protects RGCs after injury but does not potentiate the actions of the omega-3 fatty acids. The observed omega-3 fatty acid-mediated neuroprotection is likely achieved partially through ERK1/2 signaling as inhibition of this pathway by PD98059 hindered, but did not completely block, RGC protection. Our study thus enhances our current understanding of neural repair after CNS injury, including the visual system.

Mouse Strain Impacts Fatty Acid Uptake and Trafficking in Liver, Heart, and Brain: A Comparison of C57BL/6 and Swiss Webster Mice

C57BL/6 and Swiss Webster mice are used to study lipid metabolism, although differences in fatty acid uptake between these strains have not been reported. Using a steady state kinetic model, [1-(14)C]16:0, [1-(14)C]20:4n-6, or [1-(14)C]22:6n-3 was infused into awake, adult male mice and uptake into liver, heart, and brain determined. The integrated area of [1-(14)C]20:4n-6 in plasma was significantly increased in C57BL/6 mice, but [1-(14)C]16:0 and [1-(14)C]22:6n-3 were not different between groups. In heart, uptake of [1-(14)C]20:4n-6 was increased 1.7-fold in C57BL/6 mice. However, trafficking of [1-(14)C]22:6n-3 into the organic fraction of heart was significantly decreased 33 % in C57BL/6 mice. Although there were limited differences in fatty acid tracer trafficking in liver or brain, [1-(14)C]16:0 incorporation into liver neutral lipids was decreased 18 % in C57BL/6 mice. In heart, the amount of [1-(14)C]16:0 and [1-(14)C]22:6n-3 incorporated into total phospholipids were decreased 45 and 49 %, respectively, in C57BL/6 mice. This was accounted for by a 53 and 37 % decrease in [1-(14)C]16:0 and 44 and 52 % decrease in [1-(14)C]22:6n-3 entering ethanolamine glycerophospholipids and choline glycerophospholipids, respectively. In contrast, there was a significant increase in [1-(14)C]20:4n-6 esterification into all heart phospholipids of C57BL/6 mice. Although changes in uptake were limited to heart, several significant differences were found in fatty acid trafficking into heart, liver, and brain phospholipids. In summary, our data demonstrates differences in tissue fatty acid uptake and trafficking between mouse strains is an important consideration when carrying out fatty acid metabolic studies.

Behavioral experiences as drivers of oligodendrocyte lineage dynamics and myelin plasticity

Many behavioral experiences are known to promote hippocampal neurogenesis. In contrast, the ability of behavioral experiences to influence the production of oligodendrocytes and myelin sheath formation remains relatively unknown. However, several recent studies indicate that voluntary exercise and environmental enrichment can positively influence both oligodendrogenesis and myelination, and that, in contrast, social isolation can negatively influence myelination. In this review we summarize studies addressing the influence of behavioral experiences on oligodendrocyte lineage cells and myelin, and highlight potential mechanisms including experience-dependent neuronal activity, metabolites, and stress effectors, as well as both local and systemic secreted factors. Although more study is required to better understand the underlying mechanisms by which behavioral experiences regulate oligodendrocyte lineage cells, this exciting and newly emerging field has already revealed that oligodendrocytes and their progenitors are highly responsive to behavioral experiences and suggest the existence of a complex network of reciprocal interactions among oligodendrocyte lineage development, behavioral experiences, and brain function. Achieving a better understanding of these relationships may have profound implications for human health, and in particular, for our understanding of changes in brain function that occur in response to experiences. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.

A nutrient combination designed to enhance synapse formation and function improves outcome in experimental spinal cord injury

Spinal cord injury leads to major neurological impairment for which there is currently no effective treatment. Recent clinical trials have demonstrated the efficacy of Fortasyn® Connect in Alzheimer's disease. Fortasyn® Connect is a specific multi-nutrient combination containing DHA, EPA, choline, uridine monophosphate, phospholipids, and various vitamins. We examined the effect of Fortasyn® Connect in a rat compression model of spinal cord injury. For 4 or 9 weeks following the injury, rats were fed either a control diet or a diet enriched with low, medium, or high doses of Fortasyn® Connect. The medium-dose Fortasyn® Connect-enriched diet showed significant efficacy in locomotor recovery after 9 weeks of supplementation, along with protection of spinal cord tissue (increased neuronal and oligodendrocyte survival, decreased microglial activation, and preserved axonal integrity). Rats fed the high-dose Fortasyn® Connect-enriched diet for 4 weeks showed a much greater enhancement of locomotor recovery, with a faster onset, than rats fed the medium dose. Bladder function recovered quicker in these rats than in rats fed the control diet. Their spinal cord tissues showed a smaller lesion, reduced neuronal and oligodendrocyte loss, decreased neuroinflammatory response, reduced astrocytosis and levels of inhibitory chondroitin sulphate proteoglycans, and better preservation of serotonergic axons than those of rats fed the control diet. These results suggest that this multi-nutrient preparation has a marked therapeutic potential in spinal cord injury, and raise the possibility that this original approach could be used to support spinal cord injured patients.

N-3 polyunsaturated fatty acids in animal models with neuroinflammation: An update

Neuroinflammation is a characteristic of a multitude of neurological and psychiatric disorders. Modulating inflammatory pathways offers a potential therapeutic target in these disorders. Omega-3 polyunsaturated fatty acids have anti-inflammatory and pro-resolving properties in the periphery, however, their effect on neuroinflammation is less studied. This review summarizes 61 animal studies that tested the effect of omega-3 polyunsaturated fatty acids on neuroinflammatory outcomes in vivo in various models including stroke, spinal cord injury, aging, Alzheimer's disease, Parkinson's disease, lipopolysaccharide and IL-1β injections, diabetes, neuropathic pain, traumatic brain injury, depression, surgically induced cognitive decline, whole body irradiation, amyotrophic lateral sclerosis, N-methyl-D-aspartate-induced excitotoxicity and lupus. The evidence presented in this review suggests anti-neuroinflammatory properties of omega-3 polyunsaturated fatty acids, however, it is not clear by which mechanism omega-3 polyunsaturated fatty acids exert their effect. Future research should aim to isolate the effect of omega-3 polyunsaturated fatty acids on neuroinflammatory signaling in vivo and elucidate the mechanisms underlying these effects.

Dietary sources, current intakes, and nutritional role of omega-3 docosapentaenoic acid

Fish oils and long-chain omega-3 fatty acids are well recognized for their critical role in human diets. Docosapentaenoic acid (DPA, 22 : 5n-3) has always been a part of healthy nutrition, since infants obtain almost as much DPA as DHA from human milk. Fish oil supplements and ingredients, oily fish, and grass-fed beef can serve as the primary DPA sources for the general population. Although the DPA levels in fish oils are substantially lower than those of EPA and DHA, concentrated DPA products are now becoming commercially available, and DPA-based drugs are under development. Epidemiological studies show that similar to eicosapentaenoic (EPA, 20 : 5n-3) and docosahexaenoic (DHA, 22 : 6n-3) acids, DPA is linked to various improvements in human health, perhaps owing to its structural similarity to the other two molecules. Studies in mammals, platelets, and cell cultures have demonstrated that DPA reduces platelet aggregation, and improves lipid metabolism, endothelial cell migration, and resolution of chronic inflammation. Further, other in vivo and in vitro studies have shown that DPA can improve neural health. A human supplementation trial with 99.8% pure DPA suggested that it serves as a storage depot for EPA and DHA in the human body. Future randomized controlled human trials with purified DPA will help clarify its effects on human health. They may confirm the available evidence pointing to its nutritional and biological functions, unique or overlapping with those of EPA and DHA.

The use of genetic engineering techniques to improve the lipid composition in meat, milk and fish products: a review

The health-promoting properties of dietary long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFAs) for humans are well-known. Products of animal-origin enriched with n-3 LCPUFAs can be a good example of functional food, that is food that besides traditionally understood nutritional value may have a beneficial influence on the metabolism and health of consumers, thus reducing the risk of various lifestyle diseases such as atherosclerosis and coronary artery disease. The traditional method of enriching meat, milk or eggs with n-3 LCPUFA is the manipulation of the composition of animal diets. Huge progress in the development of genetic engineering techniques, for example transgenesis, has enabled the generation of many kinds of genetically modified animals. In recent years, one of the aims of animal transgenesis has been the modification of the lipid composition of meat and milk in order to improve the dietetic value of animal-origin products. This article reviews and discusses the data in the literature concerning studies where techniques of genetic engineering were used to create animal-origin products modified to contain health-promoting lipids. These studies are still at the laboratory stage, but their results have demonstrated that the transgenesis of pigs, cows, goats and fishes can be used in the future as efficient methods of production of healthy animal-origin food of high dietetic value. However, due to high costs and a low level of public acceptance, the introduction of this technology to commercial animal production and markets seems to be a distant prospect.

Enriched endogenous omega-3 fatty acids in mice protect against global ischemia injury

Transient global cerebral ischemia, one of the consequences of cardiac arrest and cardiovascular surgery, usually leads to delayed death of hippocampal cornu Ammonis1 (CA1) neurons and cognitive deficits. Currently, there are no effective preventions or treatments for this condition. Omega-3 (ω-3) PUFAs have been shown to have therapeutic potential in a variety of neurological disorders. Here, we report that the transgenic mice that express the fat-1 gene encoding for ω-3 fatty acid desaturase, which leads to an increase in endogenous ω-3 PUFAs and a concomitant decrease in ω-6 PUFAs, were protected from global cerebral ischemia injury. The results of the study show that the hippocampal CA1 neuronal loss and cognitive deficits induced by global ischemia insult were significantly less severe in fat-1 mice than in WT mice controls. The protection against global cerebral ischemia injury was closely correlated with increased production of resolvin D1, suppressed nuclear factor-kappa B activation, and reduced generation of pro-inflammatory mediators in the hippocampus of fat-1 mice compared with WT mice controls. Our study demonstrates that fat-1 mice with high endogenous ω-3 PUFAs exhibit protective effects on hippocampal CA1 neurons and cognitive functions in a global ischemia injury model.

Neurorestorative targets of dietary long-chain omega-3 fatty acids in neurological injury

Long-chain omega-3 polyunsaturated fatty acids (LC-O3PUFAs) exhibit therapeutic potential for the treatment and prevention of the neurological deficits associated with spinal cord injury (SCI). However, the mechanisms implicated in these protective responses remain unclear. The objective of the present functional metabolomics study was to identify and define the dominant metabolic pathways targeted by dietary LC-O3PUFAs. Sprague-Dawley rats were fed rodent purified chows containing menhaden fish oil-derived LC-O3PUFAs for 8 weeks before being subjected to sham or spinal cord contusion surgeries. We show, through untargeted metabolomics, that dietary LC-O3PUFAs regulate important biochemical signatures associated with amino acid metabolism and free radical scavenging in both the injured and sham-operated spinal cord. Of particular significance, the spinal cord metabolome of animals fed with LC-O3PUFAs exhibited reduced glucose levels (-48 %) and polar uncharged/hydrophobic amino acids (less than -20 %) while showing significant increases in the levels of antioxidant/anti-inflammatory amino acids and peptides metabolites, including β-alanine (+24 %), carnosine (+33 %), homocarnosine (+27 %), kynurenine (+88 %), when compared to animals receiving control diets (p < 0.05). Further, we found that dietary LC-O3PUFAs impacted the levels of neurotransmitters and the mitochondrial metabolism, as evidenced by significant increases in the levels of N-acetylglutamate (+43 %) and acetyl CoA levels (+27 %), respectively. Interestingly, this dietary intervention resulted in a global correction of the pro-oxidant metabolic profile that characterized the SCI-mediated sensorimotor dysfunction. In summary, the significant benefits of metabolic homeostasis and increased antioxidant defenses unlock important neurorestorative pathways of dietary LC-O3PUFAs against SCI.

Metabolomics uncovers dietary omega-3 fatty acid-derived metabolites implicated in anti-nociceptive responses after experimental spinal cord injury

Chronic neuropathic pain is a frequent comorbidity following spinal cord injury (SCI) and often fails to respond to conventional pain management strategies. Preventive administration of docosahexaenoic acid (DHA) or the consumption of a diet rich in omega-3 polyunsaturated fatty acids (O3PUFAs) confers potent prophylaxis against SCI and improves functional recovery. The present study examines whether this novel dietary strategy provides significant antinociceptive benefits in rats experiencing SCI-induced pain. Rats were fed control chow or chow enriched with O3PUFAs for 8weeks before being subjected to sham or cord contusion surgeries, continuing the same diets after surgery for another 8 more weeks. The paw sensitivity to noxious heat was quantified for at least 8weeks post-SCI using the Hargreaves test. We found that SCI rats consuming the preventive O3PUFA-enriched diet exhibited a significant reduction in thermal hyperalgesia compared to those consuming the normal diet. Functional neurometabolomic profiling revealed a distinctive deregulation in the metabolism of endocannabinoids (eCB) and related N-acyl ethanolamines (NAEs) at 8weeks post-SCI. We found that O3PUFAs consumption led to a robust accumulation of novel NAE precursors, including the glycerophospho-containing docosahexaenoyl ethanolamine (DHEA), docosapentaenoyl ethanolamine (DPEA), and eicosapentaenoyl ethanolamine (EPEA). The tissue levels of these metabolites were significantly correlated with the antihyperalgesic phenotype. In addition, rats consuming the O3PUFA-rich diet showed reduced sprouting of nociceptive fibers containing CGRP and dorsal horn neuron p38 mitogen-activated protein kinase (MAPK) expression, well-established biomarkers of pain. The spinal cord levels of inositols were positively correlated with thermal hyperalgesia, supporting their role as biomarkers of chronic neuropathic pain. Notably, the O3PUFA-rich dietary intervention reduced the levels of these metabolites. Collectively, these results demonstrate the prophylactic value of dietary O3PUFA against SCI-mediated chronic pain.

Fatting the brain: a brief of recent research

Fatty acids are of paramount importance to all cells, since they provide energy, function as signaling molecules, and sustain structural integrity of cellular membranes. In the nervous system, where fatty acids are found in huge amounts, they participate in its development and maintenance throughout life. Growing evidence strongly indicates that fatty acids in their own right are also implicated in pathological conditions, including neurodegenerative diseases, mental disorders, stroke, and trauma. In this review, we focus on recent studies that demonstrate the relationships between fatty acids and function and dysfunction of the nervous system. Fatty acids stimulate gene expression and neuronal activity, boost synaptogenesis and neurogenesis, and prevent neuroinflammation and apoptosis. By doing so, they promote brain development, ameliorate cognitive functions, serve as anti-depressants and anti-convulsants, bestow protection against traumatic insults, and enhance repairing processes. On the other hand, unbalance between different fatty acid families or excess of some of them generate deleterious side effects, which limit the translatability of successful results in experimental settings into effective therapeutic strategies for humans. Despite these constraints, there exists realistic evidence to consider that nutritional therapies based on fatty acids can be of benefit to several currently incurable nervous system diseases.