Dietary Docosahexaenoic Acid Improves Cognitive Function, Tissue Sparing, and Magnetic Resonance Imaging Indices of Edema and White Matter Injury in the Immature Rat after Traumatic Brain Injury

Importance of Control Groups for Evaluating Long-Term Behavioral and Cognitive Outcomes of Controlled Cortical Impact in Immature Rats

Therapies are limited for pediatric traumatic brain injury (TBI), especially for the very young who can experience long-term consequences to learning, memory, and social behavior. Animal models of pediatric TBI have yielded mechanistic insights, but demonstration of clinically relevant long-term behavioral and/or cognitive deficits has been challenging. We characterized short- and long-term outcomes in a controlled cortical impact (CCI) model of pediatric TBI using a panel of tests between 2 weeks and ∼4 months after injury. Male rats with CCI at postnatal Day (PND) 10 were compared with three control groups: Naïve, Anesthesia, and Craniotomy. Motor testing (PND 25-33), novel object recognition (NOR; PND 40-50), and multiple tasks in water maze (WM; PND 65-100) were followed by social interaction tests (PND 120-140). Anesthesia rats performed the same as Naïve rats in all tasks. TBI rats, when compared with Naïve controls, had functional impairments across most tests studied. The most sensitive cognitive processes affected by TBI included those that required fast one-trial learning (NOR, WM), flexibility of acquired memory traces (reversals in WM), response strategies (WM), or recognition memory in the setting of reciprocal social interactions. Both TBI and Craniotomy groups demonstrated increased rates of decision making across several WM tasks, suggesting disinhibition of motor responses. When the TBI group was compared with the Craniotomy group, however, deficits were detected in a limited number of outcomes. The latter included learning speed (WM), cognitive flexibility (WM), and social recognition memory. Notably, effects of craniotomy, when compared with Naïve controls, spanned across multiple tasks, and in some tasks, could reach the effect sizes observed in TBI. These results highlight the importance of appropriate control groups in pediatric CCI models. In addition, the study demonstrates the high sensitivity of comprehensive cognitive testing to detect long-term effects of early-age craniotomy and TBI and provides a template for future testing of experimental therapies.

Sphingosine-1-phosphate receptor 1 activation in the central nervous system drives cisplatin-induced cognitive impairment

Cancer-related cognitive impairment (CRCI) is a major neurotoxicity affecting more than 50% of cancer survivors. The underpinning mechanisms are mostly unknown, and there are no FDA-approved interventions. Sphingolipidomic analysis of mouse prefrontal cortex and hippocampus, key sites of cognitive function, revealed that cisplatin increased levels of the potent signaling molecule sphingosine-1-phosphate (S1P) and led to cognitive impairment. At the biochemical level, S1P induced mitochondrial dysfunction, activation of NOD-, LRR-, and pyrin domain–containing protein 3 inflammasomes, and increased IL-1β formation. These events were attenuated by systemic administration of the functional S1P receptor 1 (S1PR1) antagonist FTY720, which also attenuated cognitive impairment without adversely affecting locomotor activity. Similar attenuation was observed with ozanimod, another FDA-approved functional S1PR1 antagonist. Mice with astrocyte-specific deletion of S1pr1 lost their ability to respond to FTY720, implicating involvement of astrocytic S1PR1. Remarkably, our pharmacological and genetic approaches, coupled with computational modeling studies, revealed that cisplatin increased S1P production by activating TLR4. Collectively, our results identify the molecular mechanisms engaged by the S1P/S1PR1 axis in CRCI and establish S1PR1 antagonism as an approach to target CRCI with therapeutics that have fast-track clinical application.

Oxidative stress and mitochondrial dysfunction following traumatic brain injury: From mechanistic view to targeted therapeutic opportunities

Traumatic brain injury (TBI) is one of the most prevalent causes of permanent physical and cognitive disabilities. TBI pathology results from primary insults and a multi-mechanistic biochemical process, termed as secondary brain injury. Currently, there are no pharmacological agents for definitive treatment of patients with TBI. This article is presented with the purpose of reviewing molecular mechanisms of TBI pathology, as well as potential strategies and agents against pathological pathways. In this review article, materials were obtained by searching PubMed, Scopus, Elsevier, Web of Science, and Google Scholar. This search was considered without time limitation. Evidence indicates that oxidative stress and mitochondrial dysfunction are two key mediators of the secondary injury cascade in TBI pathology. TBI-induced oxidative damage results in the structural and functional impairments of cellular and subcellular components, such as mitochondria. Impairments of mitochondrial electron transfer chain and mitochondrial membrane potential result in a vicious cycle of free radical formation and cell apoptosis. The results of some preclinical and clinical studies, evaluating mitochondria-targeted therapies, such as mitochondria-targeted antioxidants and compounds with pleiotropic effects after TBI, are promising. As a proposed strategy in recent years, mitochondria-targeted multipotential therapy is a new hope, waiting to be confirmed. Moreover, based on the available findings, biologics, such as stem cell-based therapy and transplantation of mitochondria are novel potential strategies for the treatment of TBI; however, more studies are needed to clearly confirm the safety and efficacy of these strategies.

An Evaluation of Omega-3 Status and Intake in Canadian Elite Rugby 7s Players

Background: EPA and DHA n-3 FA play crucial roles in both neurological and cardiovascular health and high dietary intakes along with supplementation suggest potential neuroprotection and concussion recovery support. Rugby athletes have a high risk of repetitive sub-concussive head impacts which may lead to long-term neurological deficits, but there is a lack of research looking into n-3 FA status in rugby players. We examined the dietary n-3 FA intake through a FFQ and n-3 FA status by measuring the percentage of n-3 FA and O3I in elite Canadian Rugby 7s players to show distribution across O3I risk zones; high risk, <4%; intermediate risk, 4 to 8%; and low risk, >8%. Methods: n-3 FA profile and dietary intake as per FFQ were collected at the beginning of the 2017–2018 Rugby 7s season in male (n = 19; 24.84 ± 2.32 years; 95.23 ± 6.93 kg) and female (n = 15; 23.45 ± 3.10 years; 71.21 ± 5.79 kg) athletes. Results: O3I averaged 4.54% ± 1.77, with female athlete scores slightly higher, and higher O3I scores in supplemented athletes (4.82% vs. 3.94%, p = 0.183), with a greater proportion of non-supplemented athletes in the high-risk category (45.5% vs. 39.1%). Dietary intake in non-supplemented athletes did not meet daily dietary recommendations for ALA or EPA + DHA compared to supplemented athletes. Conclusions: Overall, despite supplementation, O3I score remained in the high-risk category in a proportion of athletes who met recommended n-3 FA dietary intakes, and non-supplemented athletes had a higher proportion of O3I scores in the high-risk category, suggesting that dietary intake alone may not be enough and athletes may require additional dietary and n-3 FA supplementation to reduce neurological and cardiovascular risk.

Traumatic Brain Injury: An Age-Dependent View of Post-Traumatic Neuroinflammation and Its Treatment

Traumatic brain injury (TBI) is a leading cause of death and disability all over the world. TBI leads to (1) an inflammatory response, (2) white matter injuries and (3) neurodegenerative pathologies in the long term. In humans, TBI occurs most often in children and adolescents or in the elderly, and it is well known that immune responses and the neuroregenerative capacities of the brain, among other factors, vary over a lifetime. Thus, age-at-injury can influence the consequences of TBI. Furthermore, age-at-injury also influences the pharmacological effects of drugs. However, the post-TBI inflammatory, neuronal and functional consequences have been mostly studied in experimental young adult animal models. The specificity and the mechanisms underlying the consequences of TBI and pharmacological responses are poorly understood in extreme ages. In this review, we detail the variations of these age-dependent inflammatory responses and consequences after TBI, from an experimental point of view. We investigate the evolution of microglial, astrocyte and other immune cells responses, and the consequences in terms of neuronal death and functional deficits in neonates, juvenile, adolescent and aged male animals, following a single TBI. We also describe the pharmacological responses to anti-inflammatory or neuroprotective agents, highlighting the need for an age-specific approach to the development of therapies of TBI.

Higher n-3 Polyunsaturated Fatty Acid Diet Improves Long-Term Neuropathological and Functional Outcome after Repeated Mild Traumatic Brain Injury

Repeated mild traumatic brain injury (TBI) can cause persistent neuropathological effects and is a major risk factor for chronic traumatic encephalopathy. PUFAs (n-3 polyunsaturated fatty acids) were shown to improve acute TBI outcomes in single-injury models in most cases. In this study, we demonstrate positive effects of dietary n-3 PUFA on long-term neuropathological and functional outcome in a clinically relevant model of repeated mild TBI using the Closed-Head Impact Model of Engineered Rotational Acceleration (CHIMERA). Adult mice, reared on n-3 PUFA adequate (higher n-3 PUFA) or deficient (lower n-3 PUFA) diets, were given a mild CHIMERA daily for 3 consecutive days. At 2 months after injury, visual function and spatial memory were evaluated. Glia cell activation was assessed by immunostaining using antibodies of ionized calcium-binding adaptor molecule 1 and glial fibrillary acidic protein, and axonal damage was examined using silver staining. Repeated CHIMERA (rCHIMERA)-induced gliosis was significantly suppressed in the optic tract, corpus callosum, and hippocampus of mice fed the n-3 PUFA adequate diet compared to the deficient diet group. Considerable axonal damage was detected in the optic tract after rCHIMERA, but the adequate diet group displayed less axonal damage compared to the deficient diet group. rCHIMERA induced a drastic reduction in N1 amplitude of the visual evoked potential in both diet groups and the a-wave amplitude of the electroretinogram in the deficient diet group. However, reduction of N1 and a-wave amplitude were less severe in the adequate diet group. The Morris water maze probe test indicated a significant decrease in the number of platform crossings in the deficient diet group compared to the adequate group. In summary, dietary n-3 PUFA can attenuate persistent glial cell activation and axonal damage and improve deficits in visual function and spatial memory after repeated mild TBI. These data support the neuroprotective potential of a higher n-3 PUFA diet in ameliorating the adverse outcome of repeated mild TBI.

The impact of exercise, sleep, and diet on neurocognitive recovery from mild traumatic brain injury in older adults: A narrative review

Mild traumatic brain injury (mTBI) accounts for a large majority of traumatic brain injuries sustained globally each year. Older adults, who are already susceptible to age-related declines to neurocognitive health, appear to be at an increased risk of both sustaining an mTBI and experiencing slower or impaired recovery. There is also growing evidence that mTBI is a potential risk factor for accelerated cognitive decline and neurodegeneration. Lifestyle-based interventions are gaining prominence as a cost-effective means of maintaining cognition and brain health with age. Consequently, inter-individual variations in exercise, sleep, and dietary patterns could influence the trajectory of post-mTBI neurocognitive recovery, particularly in older adults. This review synthesises the current animal and human literature centred on the mechanisms through which lifestyle-related habits and behaviours could influence acute and longer-term neurocognitive functioning following mTBI. Numerous neuroprotective processes which are impacted by lifestyle factors have been established in animal models of TBI. However, the literature is characterised by a lack of translation to human samples and limited appraisal of the interaction between ageing and brain injury. Further research is needed to better establish the therapeutic utility of applying lifestyle-based modifications to improve post-mTBI neurocognitive outcomes in older adults.

Omega-3 Fatty Acids and Vitamin D Decrease Plasma T-Tau, GFAP, and UCH-L1 in Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) results in neuronal, axonal and glial damage. Interventions targeting neuroinflammation to enhance recovery from TBI are needed. Exercise is known to improve cognitive function in TBI patients. Omega-3 fatty acids and vitamin D reportedly reduce inflammation, and in combination, might improve TBI outcomes. This study examined how an anti-inflammatory diet affected plasma TBI biomarkers, voluntary exercise and behaviors following exposure to mild TBI (mTBI). Adult, male rats were individually housed in cages fitted with running wheels and daily running distance was recorded throughout the study. A modified weight drop method induced mTBI, and during 30 days post-injury, rats were fed diets supplemented with omega-3 fatty acids and vitamin D₃ (AIDM diet), or non-supplemented AIN-76A diets (CON diet). Behavioral tests were periodically conducted to assess functional deficits. Plasma levels of Total tau (T-tau), glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase L1 (UCH-L1) and neurofilament light chain (NF-L) were measured at 48 h, 14 days, and 30 days post-injury. Fatty acid composition of food, plasma, and brain tissues was determined. In rats exposed to mTBI, NF-L levels were significantly elevated at 48 h post-injury (P < 0.005), and decreased to levels seen in uninjured rats by 14 days post-injury. T-tau, GFAP, and UCH-L1 plasma levels did not change at 48 h or 14 days post-injury. However, at 30 days post-injury, T-tau, GFAP and UCH-L1 all significantly increased in rats exposed to mTBI and fed CON diets (P < 0.005), but not in rats fed AIDM diets. Behavioral tests conducted post-injury showed that exercise counteracted cognitive deficits associated with mTBI. The AIDM diets significantly increased docosahexaenoic acid levels in plasma and brain tissue (P < 0.05), and in serum levels of vitamin D (P < 0.05). The temporal response of the four injury biomarkers examined is consistent with studies by others demonstrating acute and chronic neural tissue damage following exposure to TBI. The anti-inflammatory diet significantly altered the temporal profiles of plasma T-tau, GFAP, and UCH-L1 following mTBI. Voluntary exercise protected against mTBI-induced cognitive deficits, but had no impact on plasma levels of neurotrauma biomarkers. Thus, the prophylactic effect of exercise, when combined with an anti-inflammatory diet, may facilitate recovery in patients with mTBI.

Docosahexaenoic acid decreased inflammatory gene expression, but not 18-kDa translocator protein binding, in rat pup brain after controlled cortical impact

BACKGROUND

Traumatic brain injury is the leading cause of acquired neurologic disability in children. In our model of pediatric traumatic brain injury, controlled cortical impact (CCI) in rat pups, docosahexaenoic acid (DHA) improved lesion volume and cognitive testing as late as postinjury day (PID) 50. Docosahexaenoic acid decreased proinflammatory messenger RNA (mRNA) in microglia and macrophages at PIDs 3 and 7, but not 30. We hypothesized that DHA affected inflammatory markers differentially relative to impact proximity, early and persistently after CCI.

METHODS

To provide a temporal snapshot of regional neuroinflammation, we measured 18-kDa translocator protein (TSPO) binding using whole brain autoradiography at PIDs 3, 7, 30, and 50. Guided by TSPO results, we measured mRNA levels in contused cortex and underlying hippocampus for genes associated with proinflammatory and inflammation-resolving states at PIDs 2 and 3.

RESULTS

Controlled cortical impact increased TSPO binding at all time points, most markedly at PID 3 and in regions closest to impact, not blunted by DHA. Controlled cortical impact increased cortical and hippocampal mRNA proinflammatory markers, blunted by DHA at PID 2 in hippocampus.

CONCLUSION

Controlled cortical impact increased TSPO binding in the immature brain in a persistent manner more intensely with more severe injury, not altered by DHA. Controlled cortical impact increased PIDs 2 and 3 mRNA levels of proinflammatory and inflammation-resolving genes. Docosahexaenoic acid decreased proinflammatory markers associated with inflammasome activation at PID 2. We speculate that DHA's salutary effects on long-term outcomes result from early effects on the inflammasome. Future studies will examine functional effects of DHA on microglia both early and late after CCI.

Dietary manipulation of vulnerability to traumatic brain injury-induced neuronal plasma membrane permeability

Traumatic brain injury (TBI) can produce physical disruptions in the plasma membranes of neurons, referred to as mechanoporation, which lead to increased cell permeability. We suspect that such trauma-induced membrane disruptions may be influenced by the physical properties of the plasma membrane, such as elasticity or rigidity. These membrane properties are influenced by lipid composition, which can be modulated via diet, leading to the intriguing possibility of prophylactically altering diet to confer resiliency to this mechanism of acute neuronal damage in TBI. In this proof-of-concept study, we used three different diets-one high in polyunsaturated fatty acids suggested to increase elasticity (Fish Oil), one high in saturated fatty acids and cholesterol suggested to increase rigidity (High Fat), and one standard rat chow (Control)-to alter brain plasma membrane lipid composition before subjecting rats to lateral fluid percussion injury (FPI). Lipid analysis (n = 12 rats) confirmed that diets altered brain fatty acid composition after 4 weeks of feeding, with the Fish Oil diet increasing unsaturated fatty acids, and interestingly, the High Fat diet increasing omega-6 docosapentaenoic acid. One cohort of animals (n = 34 rats) was assessed immediately after FPI or sham injury for acute changes in neuronal membrane permeability in the injury-adjacent cortex. Surprisingly, sham animals fed Fish Oil had increased membrane permeability, suggesting altered passive membrane properties. In contrast, injured animals fed the High Fat diet displayed less intense uptake of permeability marker, suggesting a reduced extent of injury-induced plasma membrane disruption, although the density of affected cells matched the other diet groups. In a separate cohort survived for 7 days after FPI (n = 48 rats), animals fed the High Fat diet exhibited a reduced lesion area. At both time points there were no statistically significant differences in inflammation. Unexpectedly, these results indicate that the High Fat diet, as opposed to the Fish Oil diet, beneficially modulated acute plasma membrane permeability and resulted in a smaller lesion size at 7 days post-injury. Additional studies are necessary to determine the impact of these various diets on behavioral outcomes post-TBI. Further investigation is also needed to understand the physical properties in neuronal plasma membranes that may underlie increased resiliency to trauma-induced disruptions and, importantly, to understand how these properties may be influenced by targeted dietary modifications for vulnerable populations.

Nutritional interventions to improve neurophysiological impairments following traumatic brain injury: A systematic review

Traumatic brain injury (TBI) accounts for significant global health burden. Effects of TBI can become chronic even following mild injury. There is a need to develop effective therapies to attenuate the damaging effects of TBI and improve recovery outcomes. This literature review using a priori criteria (PROSPERO; CRD42018100623) summarized 43 studies between January 1998 and July 2019 that investigated nutritional interventions (NUT) delivered with the objective of altering neurophysiological (NP) outcomes following TBI. Risk of bias was assessed for included studies, and NP outcomes recorded. The systematic search resulted in 43 of 3,748 identified studies met inclusion criteria. No studies evaluated the effect of a NUT on NP outcomes of TBI in humans. Biomarkers of morphological changes and apoptosis, oxidative stress, and plasticity, neurogenesis, and neurotransmission were the most evaluated NP outcomes across the 43 studies that used 2,897 animals. The risk of bias was unclear in all reviewed studies due to poorly detailed methodology sections. Taking these limitations into account, anti-oxidants, branched chain amino acids, and ω-3 polyunsaturated fatty acids have shown the most promising pre-clinical results for altering NP outcomes following TBI. Refinement of pre-clinical methodologies used to evaluate effects of interventions on secondary damage of TBI would improve the likelihood of translation to clinical populations.

A Pilot Study Assessing the Impact of rs174537 on Circulating Polyunsaturated Fatty Acids and the Inflammatory Response in Patients with Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability in persons under age 45. The hallmark secondary injury profile after TBI involves dynamic interactions between inflammatory and metabolic pathways including fatty acids. Omega-3 polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA) have been shown to provide neuroprotective benefits by minimizing neuroinflammation in rodents. These effects have been less conclusive in humans, however. We postulate genetic variants influencing PUFA metabolism in humans could contribute to these disparate findings. Therefore, we sought to (1) characterize the circulating PUFA response and (2) evaluate the impact of rs174537 on inflammation after TBI. A prospective, single-center, observational pilot study was conducted to collect blood samples from Level-1 trauma patients (N = 130) on admission and 24 h post-admission. Plasma was used to quantify PUFA levels and inflammatory cytokines. Deoxyribonucleic acid was extracted and genotyped at rs174537. Associations between PUFAs and inflammatory cytokines were analyzed for all trauma cases and stratified by race (Caucasians only), TBI (TBI: N = 47; non-TBI = 83) and rs174537 genotype (GG: N = 33, GT/TT: N = 44). Patients with TBI had higher plasma DHA levels compared with non-TBI at 24 h post-injury (p = 0.013). The SNP rs174537 was associated with both PUFA levels and inflammatory cytokines (p < 0.05). Specifically, TBI patients with GG genotype exhibited the highest plasma levels of DHA (1.33%) and interleukin-8 (121.5 ± 43.3 pg/mL), which were in turn associated with poorer outcomes. These data illustrate the impact of rs174537 on the post-TBI response. Further work is needed to ascertain how this genetic variant directly influences inflammation after trauma.

Diffusion Tensor Imaging-Based Studies at the Group-Level Applied to Animal Models of Neurodegenerative Diseases

The understanding of human and non-human microstructural brain alterations in the course of neurodegenerative diseases has substantially improved by the non-invasive magnetic resonance imaging (MRI) technique of diffusion tensor imaging (DTI). Animal models (including disease or knockout models) allow for a variety of experimental manipulations, which are not applicable to humans. Thus, the DTI approach provides a promising tool for cross-species cross-sectional and longitudinal investigations of the neurobiological targets and mechanisms of neurodegeneration. This overview with a systematic review focuses on the principles of DTI analysis as used in studies at the group level in living preclinical models of neurodegeneration. The translational aspect from in-vivo animal models toward (clinical) applications in humans is covered as well as the DTI-based research of the non-human brains' microstructure, the methodological aspects in data processing and analysis, and data interpretation at different abstraction levels. The aim of integrating DTI in multiparametric or multimodal imaging protocols will allow the interrogation of DTI data in terms of directional flow of information and may identify the microstructural underpinnings of neurodegeneration-related patterns.

Antioxidant Therapies in Traumatic Brain Injury

Due to a multiplicity of causes provoking traumatic brain injury (TBI), TBI is a highly heterogeneous pathology, characterized by high mortality and disability rates. TBI is an acute neurodegenerative event, potentially and unpredictably evolving into sub-chronic and chronic neurodegenerative events, with transient or permanent neurologic, cognitive, and motor deficits, for which no valid standardized therapies are available. A vast body of literature demonstrates that TBI-induced oxidative/nitrosative stress is involved in the development of both acute and chronic neurodegenerative disorders. Cellular defenses against this phenomenon are largely dependent on low molecular weight antioxidants, most of which are consumed with diet or as nutraceutical supplements. A large number of studies have evaluated the efficacy of antioxidant administration to decrease TBI-associated damage in various animal TBI models and in a limited number of clinical trials. Points of weakness of preclinical studies are represented by the large variability in the TBI model adopted, in the antioxidant tested, in the timing, dosages, and routes of administration used, and in the variety of molecular and/or neurocognitive parameters evaluated. The analysis of the very few clinical studies does not allow strong conclusions to be drawn on the real effectiveness of antioxidant administration to TBI patients. Standardizing TBI models and different experimental conditions, as well as testing the efficacy of administration of a cocktail of antioxidants rather than only one, should be mandatory. According to some promising clinical results, it appears that sports-related concussion is probably the best type of TBI to test the benefits of antioxidant administration.

Effects of controlled cortical impact and docosahexaenoic acid on rat pup fatty acid profiles

Traumatic brain injury (TBI) is the leading cause of acquired neurologic disability in children, particularly in those under four years old. During this period, rapid brain growth demands higher Docosahexaenoic Acid (DHA) intake. DHA is an essential fatty acid and brain cell component derived almost entirely from the diet. DHA improved neurologic outcomes and decreased inflammation after controlled cortical impact (CCI) in 17-day old (P17) rats, our established model of pediatric TBI. In adult rodents, TBI decreases brain DHA. We hypothesized that CCI would decrease rat brain DHA at post injury day (PID) 60, blunted by 0.1% DHA diet. We quantitated fatty acids using Gas Chromatography-Mass Spectrometry. We provided 0.1% DHA before CCI to ensure high DHA in dam milk. We compared brain DHA in rats after 60 days of regular (REG) or DHA diet to SHAM pups on REG diet. Brain DHA decreased in REGCCI, not in DHACCI, relative to SHAMREG. In a subsequent experiment, we gave rat pups DHA or vehicle intraperitoneally after CCI followed by DHA or REG diet for 60 days. REG increased brain Docosapentaenoic Acid (n-6 DPA, a brain DHA deficiency marker) relative to SHAMDHA and DHACCI pups (p < 0.001, diet effect). DHA diet nearly doubled DHA and decreased n-6 DPA in blood but did not increase brain DHA content (p < 0.0001, diet effect). We concluded that CCI or craniotomy alone induces a mild DHA deficit as shown by increased brain DPA.

Effect of docosahexaenoic acid on the recovery of motor function in rats with spinal cord injury: a meta-analysis

Objective:

Studies have shown that docosahexaenoic acid (DHA) has a beneficial effect in the treatment of spinal cord injury. A meta-analysis was used to study the effect of DHA on the neurological recovery in the rat spinal cord injury model, and the relationship between the recovery of motor function after spinal cord injury and the time and method of administration and the dose of DHA.

Data source:

Published studies on the effect of DHA on spinal cord injury animal models from seven databases were searched from their inception to January 2019, including PubMed, MEDLINE, EMBASE, the China National Knowledge Infrastructure, Wanfang, VIP, and SinoMed databases. The search terms included “spinal cord injury” “docosahexaenoic acid”, and “rats”.

Data selection:

Studies that evaluated the influence of DHA in rat models of spinal cord injury for locomotor functional recovery were included. The intervention group included any form of DHA treatment and the control group included treatment with normal saline, vehicle solution or no treatment. The Systematic Review Centre for Laboratory animal Experimentation’s risk of bias assessment tool was used for the quality assessment of the included studies. Literature inclusion, quality evaluation and data extraction were performed by two researchers. Meta-analysis was then conducted on all studies that met the inclusion criteria. Statistical analysis was performed on the data using RevMan 5.1.2. software.

Outcome measures:

The primary outcome measure was the score on the Basso, Beattie, and Bresnahan scale. Secondary outcome measures were the sloping plate test, balance beam test, stair test and grid exploration test.

Results:

A total of 12 related studies were included, 3 of which were of higher quality and the remaining 9 were of lower quality. The highest mean Basso, Beattie, and Bresnahan scale score occurred at 42 days after DHA treatment in spinal cord injury rats. At 21 days after treatment, the mean difference in Basso, Beattie, Bresnahan scores between the DHA group and the control group was the most significant (pooled MD = 4.14; 95% CI = 3.58–4.70; P < 0.00001). In the subgroup analysis, improvement in the Basso, Beattie, and Bresnahan scale score was more significant in rats administered DHA intravenously (pooled MD = 2.74; 95% CI = 1.41–4.07; P < 0.0001) and subcutaneously (pooled MD = 2.99; 95% CI = 2.29–3.69; P < 0.00001) than in the groups administered DHA orally (pooled MD = 3.04; 95% CI = –1.01 to 7.09; P = 0.14). Intravenous injection of DHA at 250 nmol/kg (pooled MD = 2.94; 95% CI = 2.47–3.41; P < 0.00001] and 1000 nmol/kg [pooled MD = 3.60; 95% CI = 2.66–4.54; P < 0.00001) significantly improved the Basso, Beattie, and Bresnahan scale score in rats and promoted the recovery of motor function.

Conclusion:

DHA can promote motor functional recovery after spinal cord injury in rats. The administration of DHA by intravenous or subcutaneous injection is more effective than oral administration of DHA. Intravenous injection of DHA at doses of 250 nmol/kg or 1000 nmol/kg is beneficial. Because of the small number and the low quality of the included studies, more high-quality research is needed in future to substantiate the results.

Docosahexaenoic acid decreased neuroinflammation in rat pups after controlled cortical impact

Traumatic brain injury (TBI) is the leading cause of acquired neurologic disability in children, yet specific therapies to treat TBI are lacking. Therapies that decrease the inflammatory response and enhance a reparative immune action may decrease oxidative damage and improve outcomes after TBI. Docosahexaenoic acid (DHA) modulates the immune response to injury in many organs. DHA given in the diet before injury decreased rat pup cognitive impairment, oxidative stress and white matter injury in our developmental TBI model using controlled cortical impact (CCI). Little is known about DHA effects on neuroinflammation in the developing brain. Further, it is not known if DHA given after developmental TBI exerts neuroprotective effects. We hypothesized that acute DHA treatment would decrease oxidative stress and improve cognitive outcome, associated with decreased pro-inflammatory activation of microglia, the brain's resident macrophages.

METHODS

17-day-old rat pups received intraperitoneal DHA or vehicle after CCI or SHAM surgery followed by DHA diet or continuation of REG diet to create DHACCI, REGCCI, SHAMDHA and SHAMREG groups. We measured brain nitrates/nitrites (NOx) at post injury day (PID) 1 to assess oxidative stress. We tested memory using Novel Object Recognition (NOR) at PID14. At PID 3 and 7, we measured reactivity of microglial activation markers Iba1, CD68 and CD206 and astrocyte marker GFAP in the injured cortex. At PID3, 7 and 30 we measured mRNA levels of inflammation-related genes and transcription factors in flow-sorted brain cells.

RESULTS

DHA decreased oxidative stress at PID1 and pro-inflammatory microglial activation at PID3. CCI increased mRNA levels of two interferon regulatory family transcription factors, blunted by DHA, particularly in microglia-enriched cell populations at PID7. CCI increased mRNA levels of genes associated with "pro- " and "anti-" inflammatory activity at PID3, 7 and 30. Most notably within the microglia-enriched population, DHA blunted increased mRNA levels of pro-inflammatory genes at PID 3 and 7 and of anti-inflammatory genes at PID 30. Particularly in microglia, we observed parallel activation of pro-inflammatory and anti-inflammatory genes. DHA improved performance on NOR at PID14 after CCI.

CONCLUSIONS

DHA decreased oxidative stress and histologic and mRNA markers of microglial pro-inflammatory activation in rat pup brain acutely after CCI associated with improved short term cognitive function. DHA administration after CCI has neuroprotective effects, which may result in part from modulation of microglial activation toward a less inflammatory profile in the first week after CCI. Future and ongoing studies will focus on phagocytic function and reactive oxygen species production in microglia and macrophages to test functional effects of DHA on neuroinflammation in our model. Given its favorable safety profile in children, DHA is a promising candidate therapy for pediatric TBI.

Sex differences in pediatric traumatic brain injury

The response of the developing brain to traumatic injury is different from the response of the mature, adult brain. There are critical developmental trajectories in the young brain, whereby injury can lead to long term functional abnormalities. Emerging preclinical and clinical literature supports the presence of significant sex differences in both the response to and the recovery from pediatric traumatic brain injury (TBI). These sex differences are seen at all pediatric ages, including neonates/infants, pre-pubertal children, and adolescents. As importantly, the response to neuroprotective therapies or treatments can differ between male and females subjects. These sex differences can result from several biologic origins, and may manifest differently during the various phases of brain and body development. Recognizing and understanding these potential sex differences is crucial, and should be considered in both preclinical and clinical studies of pediatric TBI.

The Omega-3 Index in National Collegiate Athletic Association Division I Collegiate Football Athletes

CONTEXT

The essential omega-3 fatty acids (ω-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exhibit vital biological roles and are critical for cardiovascular and neurologic health. Compared with the general population, football athletes may be at an increased risk of cardiovascular disease. Further, those same athletes are also exposed to repetitive head impacts, which may lead to long-term neurologic deficits. Both diets high in ω-3 FAs and supplementation with ω-3 FAs have been reported to reduce the risk of cardiovascular disease, and early evidence suggests a potential neuroprotective effect of supplementation.

OBJECTIVE

To determine the (1) erythrocyte content of DHA and EPA, as measured by the Omega-3 Index, expressed as a percentage of total fatty acids, in National Collegiate Athletic Association Division I football athletes and (2) distribution across the Omega-3 Index risk zones established for cardiovascular disease: high risk, <4%; intermediate risk, 4% to 8%; and low risk, >8%.

DESIGN

Cross-sectional descriptive study.

SETTING

Multicenter trial.

PATIENTS OR OTHER PARTICIPANTS

Deidentified data including complete erythrocyte fatty acid profile from the 2017-2018 season, age at time of testing, height, weight, and ethnicity were collected from 404 athletes.

MAIN OUTCOME MEASURE(S)

Omega-3 Index.

RESULTS

About 34% of athletes (n = 138) had an Omega-3 Index considered high risk (<4%), and 66% (n = 266) had a risk considered intermediate (4%-8%). None had a low-risk Omega-3 Index.

CONCLUSIONS

The Omega-3 Index is a simple, minimally invasive test of ω-3 FA status. Our data indicate that football athletes may be deficient in the ω-3 FAs DHA and EPA. The fact that no athlete had an Omega-3 Index associated with low risk suggests football athletes may be at increased risk for cardiovascular disease in later life.

Diffusion Magnetic Resonance Imaging Unveils the Spatiotemporal Microstructural Gray Matter Changes following Injury in the Rodent Brain

Traumatic brain injury (TBI) is associated with gray and white matter alterations in brain tissue. Gray matter alterations are not yet as well studied as those of the white matter counterpart. This work utilized T2-weighted structural imaging, diffusion tensor imaging (DTI), and diffusion kurtosis imaging to unveil the gray matter changes induced in a controlled cortical impact (CCI) mouse model of TBI at 5 h, 1 day, 3 days, 7 days, 14 days, and 30 days post-CCI. A cross-sectional histopathology approach was used to confer validity of the magnetic resonance imaging (MRI) data by performing cresyl violet staining and glial fibrillary acidic protein (GFAP) immunohistochemistry. The results demonstrated a significant increase in lesion volume up to 3 days post-injury followed by a significant decrease in the cavity volume for the period of 1 month. GFAP signals peaked on Day 7 and persisted until Day 30 in both ipsilateral and contralateral hippocampus, ipsilateral cortex, and thalamic areas. An increase in fractional anisotropy (FA) was seen at Day 7 in the pericontusional area but decreased FA in the contralateral cortex, hippocampus, and thalamus. Mean diffusivity (MD) was significantly lower in the pericontusional cortex. Increased MD and decreased mean kurtosis were limited to the injury site on Days 7 to 30 and to the contralateral hippocampus and thalamus on Days 3 and 7. This work is one of the few cross-sectional studies to demonstrate a link between MRI measures and histopathological readings to track gray matter changes in the progression of TBI.

Regional differences of hypothermia on oxidative stress following hypoxia-ischemia: a study of DHA and hypothermia on brain lipid peroxidation in newborn piglets

Background Oxidative stress plays an important part in the pathophysiology of hypoxic-ischemic encephalopathy (HIE) and is reliably measured through prostanoids following lipid peroxidation of polyunsaturated fatty acids (PUFAs). The aim of the study is to measure oxidative stress in the prefrontal cortex, white matter and hippocampus in the brains of hypoxic-ischemic piglets treated with docosahexaenoic acid (DHA) and therapeutic hypothermia (TH) and investigate the additive effects of DHA on hypothermia by factorial design. Methods Fifty-five piglets were randomized as having severe global hypoxia (n=48) or not (sham, n=7). Hypoxic piglets were further randomized: vehicle (VEH), DHA, VEH+hypothermia (HT) or HT+DHA. A total of 5 mg/kg DHA was given intravenously 210 min after the end of hypoxia. Brain tissues were analyzed using liquid chromatography triple quadrupole mass spectrometry technique (LC-MS). A two-way analysis of variance (ANOVA) was performed with DHA and HT as main effects. Results In the white matter, we found main effects of DHA on DH-isoprostanes (P=0.030) and a main effect of HT on F4-neuroprostanes (F4-NeuroPs) (P=0.007), F2-isoprostanes (F2-IsoPs) (P=0.043) and DH-isoprostanes (P=0.023). In the cortex, the ANOVA analysis showed the interactions of main effects between DHA and HT for neurofuranes (NeuroFs) (P=0.092) and DH-isoprostanes (P=0.015) as DHA significantly reduced lipid peroxidation in the absence of HT. DHA compared to VEH significantly reduced NeuroFs (P=0.019) and DH-isoprostanes (P=0.010). No differences were found in the hippocampus. Conclusion After severe hypoxia, HT reduced lipid peroxidation in the white matter but not in the cortical gray matter. HT attenuated the reducing effect of DHA on lipid peroxidation in the cortex. Further studies are needed to determine whether DHA can be an effective add-on therapy for TH.

Vasogenic cerebral edema associated with the disability in activities of daily living in patients with chronic obstructive pulmonary disease

INTRODUCTION

The aim of this study was to explore whether patients with chronic obstructive pulmonary disease (COPD) develop vasogenic cerebral edema, and whether this edema contributes to the COPD-related disability.

METHODS

Eighteen stable patients with COPD and 17 matched healthy volunteers were enrolled. Apparent diffusion coefficient (ADC) values were calculated by voxel-based analysis using DTI-Studio software based on diffusion tensor imaging. COPD-related disability was calculated using activities of daily living (ADL) scale.

RESULTS

In patients with COPD, ADC increased in the white matter fiber tracts including the bilateral anterior cingulum and posterior corpus callosum and in the white matter fibers connecting the bilateral insular cortices, sub-lobar cortices, and pars triangularis cortices and the left rectus and olfactory gyrus. However, after further controlling for cigarette smoking, the difference in ADC values in the posterior corpus callosum between groups disappeared. Patients with COPD had significantly higher scores in ADL than that in controls. Moreover, ADL scores were positively correlated with the increased regional ADC values.

CONCLUSION

Vasogenic cerebral edema occurs in patients with COPD. Cigarette smoking may be a risk factor for COPD-related vasogenic edema. Vasogenic cerebral edema may be related to the COPD-related ADL impairment.

Docosahexaenoic acid-containing choline phospholipid modulates LPS-induced neuroinflammation in vivo and in microglia in vitro

Background

Neuroinflammatory processes are considered a double-edged sword, having both protective and detrimental effects in the brain. Microglia, the brain’s resident innate immune cells, are a key component of neuroinflammatory response. There is a growing interest in developing drugs to target microglia and control neuroinflammatory processes. In this regard, docosahexaenoic acid (DHA), the brain’s n-3 polyunsaturated fatty acid, is a promising molecule to regulate pro-inflammatory microglia and cytokine production. Several works reported that the bioavailability of DHA to the brain is higher when DHA is acylated to phospholipid. In this work, we analyzed the anti-inflammatory activity of DHA-phospholipid, either acetylated at the sn-1 position (AceDoPC, a stable form thought to have superior access to the brain) or acylated with palmitic acid at the sn-1 position (PC-DHA) using a lipopolysaccharide (LPS)-induced neuroinflammation model both in vitro and in vivo.

Methods

In vivo, adult C57Bl6/J mice were injected intravenously (i.v.) with either AceDoPC or PC-DHA 24 h prior to LPS (i.p.). For in vitro studies, immortalized murine microglia cells BV-2 were co-incubated with DHA forms and LPS. AceDoPC and PC-DHA effect on brain or BV-2 PUFA content was assessed by gas chromatography. LPS-induced pro-inflammatory cytokines interleukin IL-1β, IL-6, and tumor necrosis factor (TNF) α production were measured by quantitative PCR (qPCR) or multiplex. IL-6 receptors and associated signaling pathway STAT3 were assessed by FACS analysis and western-blot in vitro.

Results

In vivo, a single injection of AceDoPC or PC-DHA decreased LPS-induced IL-6 production in the hippocampus of mice. This effect could be linked to their direct effect on microglia, as revealed in vitro. In addition, AceDoPC or PC-DHA reduced IL-6 receptor while only AceDoPC decreased IL-6-induced STAT3 phosphorylation.

Conclusions

These results highlight the potency of administered DHA—acetylated to phospholipids—to rapidly regulate LPS-induced neuroinflammatory processes through their effect on microglia. In particular, both IL-6 production and signaling are targeted by AceDoPC in microglia.

Establishment of an ideal time window model in hypothermic-targeted temperature management after traumatic brain injury in rats

Although hypothermic-targeted temperature management (HTTM) holds great potential for the treatment of traumatic brain injury (TBI), translation of the efficacy of hypothermia from animal models to TBI patientshas no entire consistency. This study aimed to find an ideal time window model in experimental rats which was more in accordance with clinical practice through the delayed HTTM intervention. Sprague-Dawley rats were subjected to unilateral cortical contusion injury and received therapeutic hypothermia at 15mins, 2 h, 4 h respectively after TBI. The neurological function was evaluated with the modified neurological severity score and Morris water maze test. The brain edema and morphological changes were measured with the water content and H&E staining. Brain sections were immunostained with antibodies against DCX (a neuroblast marker) and GFAP (an astrocyte marker). The apoptosis levels in the ipsilateral hippocampi and cortex were examined with antibodies against the apoptotic proteins Bcl-2, Bax, and cleaved caspase-3 by the immunofluorescence and western blotting. The results indicated that each hypothermia therapy group could improve neurobehavioral and cognitive function, alleviate brain edema and reduce inflammation. Furthermore, we observed that therapeutic hypothermia increased DCX expression, decreased GFAP expression, upregulated Bcl-2 expression and downregulated Bax and cleaved Caspase-3 expression. The above results suggested that HTTM at 2h or even at 4h post-injury revealed beneficial brain protection similarly, despite the best effect at 15min post-injury. These findings may provide relatively ideal time window models, further making the following experimental results more credible and persuasive.

Nutrition practices and knowledge among NCAA Division III football players

Background

Participation in collegiate American football is physically demanding and may have long-term health implications, particularly in relation to cardiovascular and neurological health. National Collegiate Athletic Association (NCAA) Division III (DIII) football players are a relatively unstudied population, particularly in terms of their dietary habits and knowledge. The aim of the present study was to descriptively evaluate the dietary intake of DIII football players including a subset of linemen and assess the nutritional knowledge and sources of information of these athletes.

Methods

The study sample was 88 DIII football players including a subset of nine linemen. All participants completed a food frequency questionnaire, and a nutritional knowledge questionnaire that included a quiz and questions about their main sources of nutrition information. Heights and body masses were also recorded. The linemen submitted written 3-day diet records for assessment of their dietary intake.

Results

Of the 88 participants, >50% reported consuming starches/grains, meat and dairy daily, but <50% reported consuming fruits and vegetables daily. Protein powders were the most commonly used supplements (33% reported daily use). Compared to dietary recommendations, linemen consumed high amounts of total fat, saturated fat, dietary cholesterol, sodium, and potassium, but were low in carbohydrates, fiber, and essential fats. The mean nutrition knowledge quiz score for the 88 participants was 55.2%. Those who had taken a nutrition or health course in college scored significantly higher on the quiz than those who had not. Participants reported relying primarily on coaches, websites, and athletic trainers (ATs) for nutritional guidance; ATs were the most trusted source.

Conclusions

DIII football players had dietary habits that may both mitigate and increase their risk of chronic diseases. These athletes have room to improve their nutrition knowledge. Their reliance on athletic team staff for nutrition guidance highlights the importance of nutrition education for both athletes and staff and the potential role of a registered dietitian nutritionist.

Electronic supplementary material

The online version of this article (doi:10.1186/s12970-017-0170-2) contains supplementary material, which is available to authorized users.

Effects of DHA on Hippocampal Autophagy and Lysosome Function After Traumatic Brain Injury

Traumatic brain injury (TBI) triggers endoplasmic reticulum (ER) stress and impairs autophagic clearance of damaged organelles and toxic macromolecules. In this study, we investigated the effects of the post-TBI administration of docosahexaenoic acid (DHA) on improving hippocampal autophagy flux and cognitive functions of rats. TBI was induced by cortical contusion injury in Sprague-Dawley rats, which received DHA (16 mg/kg in DMSO, intraperitoneal administration) or vehicle DMSO (1 ml/kg) with an initial dose within 15 min after the injury, followed by a daily dose for 3 or 7 days. First, RT-qPCR reveals that TBI induced a significant elevation in expression of autophagy-related genes in the hippocampus, including SQSTM1/p62 (sequestosome 1), lysosomal-associated membrane proteins 1 and 2 (Lamp1 and Lamp2), and cathepsin D (Ctsd). Upregulation of the corresponding autophagy-related proteins was detected by immunoblotting and immunostaining. In contrast, the DHA-treated rats did not exhibit the TBI-induced autophagy biogenesis and showed restored CTSD protein expression and activity. T₂-weighted images and diffusion tensor imaging (DTI) of ex vivo brains showed that DHA reduced both gray matter and white matter damages in cortical and hippocampal tissues. DHA-treated animals performed better than the vehicle control group on the Morris water maze test. Taken together, these findings suggest that TBI triggers sustained stimulation of autophagy biogenesis, autophagy flux, and lysosomal functions in the hippocampus. Swift post-injury DHA administration restores hippocampal lysosomal biogenesis and function, demonstrating its therapeutic potential.

Imaging and serum biomarkers reflecting the functional efficacy of extended erythropoietin treatment in rats following infantile traumatic brain injury

OBJECTIVE Traumatic brain injury (TBI) is a leading cause of death and severe morbidity for otherwise healthy full-term infants around the world. Currently, the primary treatment for infant TBI is supportive, as no targeted therapies exist to actively promote recovery. The developing infant brain, in particular, has a unique response to injury and the potential for repair, both of which vary with maturation. Targeted interventions and objective measures of therapeutic efficacy are needed in this special population. The authors hypothesized that MRI and serum biomarkers can be used to quantify outcomes following infantile TBI in a preclinical rat model and that the potential efficacy of the neuro-reparative agent erythropoietin (EPO) in promoting recovery can be tested using these biomarkers as surrogates for functional outcomes. METHODS With institutional approval, a controlled cortical impact (CCI) was delivered to postnatal Day (P)12 rats of both sexes (76 rats). On postinjury Day (PID)1, the 49 CCI rats designated for chronic studies were randomized to EPO (3000 U/kg/dose, CCI-EPO, 24 rats) or vehicle (CCI-veh, 25 rats) administered intraperitoneally on PID1-4, 6, and 8. Acute injury (PID3) was evaluated with an immunoassay of injured cortex and serum, and chronic injury (PID13-28) was evaluated with digitized gait analyses, MRI, and serum immunoassay. The CCI-veh and CCI-EPO rats were compared with shams (49 rats) primarily using 2-way ANOVA with Bonferroni post hoc correction. RESULTS Following CCI, there was 4.8% mortality and 55% of injured rats exhibited convulsions. Of the injured rats designated for chronic analyses, 8.1% developed leptomeningeal cyst-like lesions verified with MRI and were excluded from further study. On PID3, Western blot showed that EPO receptor expression was increased in the injured cortex (p = 0.008). These Western blots also showed elevated ipsilateral cortex calpain degradation products for αII-spectrin (αII-SDPs; p < 0.001), potassium chloride cotransporter 2 (KCC2-DPs; p = 0.037), and glial fibrillary acidic protein (GFAP-DPs; p = 0.002), as well as serum GFAP (serum GFAP-DPs; p = 0.001). In injured rats multiplex electrochemiluminescence analyses on PID3 revealed elevated serum tumor necrosis factor alpha (TNFα p = 0.01) and chemokine (CXC) ligand 1 (CXCL1). Chronically, that is, in PID13-16 CCI-veh rats, as compared with sham rats, gait deficits were demonstrated (p = 0.033) but then were reversed (p = 0.022) with EPO treatment. Diffusion tensor MRI of the ipsilateral and contralateral cortex and white matter in PID16-23 CCI-veh rats showed widespread injury and significant abnormalities of functional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD); MD, AD, and RD improved after EPO treatment. Chronically, P13-P28 CCI-veh rats also had elevated serum CXCL1 levels, which normalized in CCI-EPO rats. CONCLUSIONS Efficient translation of emerging neuro-reparative interventions dictates the use of age-appropriate preclinical models with human clinical trial-compatible biomarkers. In the present study, the authors showed that CCI produced chronic gait deficits in P12 rats that resolved with EPO treatment and that chronic imaging and serum biomarkers correlated with this improvement.

Diffusion Imaging of White Matter In Schizophrenia: Progress and Future Directions

Diffusion tensor imaging (DTI) is a powerful tool for the in-vivo assessment of white matter microstructure. The application of DTI methodologies to the study of schizophrenia has supported and advanced the hypothesis of schizophrenia as a disorder of disrupted connectivity. In the context of impaired structural connectivity, the extended time frame of white matter development may offer unique opportunities for treatment that can capitalize on the neural flexibility that is still present in the period leading up to and after disease onset. Therefore, it is important to gain a clear understanding of white matter deficits and how they may emerge and change across the illness. However, while there is broad consistency in the findings of white matter deficits in patients with schizophrenia, there is also a great deal of variability in specific findings across studies. In this review, the aim is to move beyond summarizing case-control analyses, to consider the many factors that may impact DTI measures, to explain variability of findings, and to explore future directions for the field. The topics explored include ways to parse DTI patterns associated with different disease subtypes, ways in which novel and established treatments might interact with or enhance white matter, ways of dissociating developmental change from the disease process itself, and understanding the role of emerging analytic methodologies.

Effects of docosahexaenoic acid on learning and memory impairment induced by repeated propofol anesthesia in young rats

The aim of the present study was to investigate the effects of docosahexaenoic acid (DHA) on the learning and memory ability of young rats exposed to propofol, and its underlying mechanisms. Sprague Dawley rats (n=60) were randomly divided into six groups: Control group (group A); solvent control group (group B); propofol group (group C); low-dose DHA + propofol group (group D); medium dose DHA + propofol group (group E); and high-dose DHA + propofol group (group F). The Morris water maze (MWM) test was performed to evaluate the rats' learning and memory ability, and tissue samples from the hippocampi of the rats were obtained for biochemical analysis. The results of the MWM test revealed that DHA supplementation administered to young rats led to an evident decrease in the latency to find the maze platform, and a significant increase in the number of platform crossings in groups E and F compared with group C (P<0.05). High-performance liquid chromatography indicated that glutamate concentration levels were significantly lower and γ-aminobutyric acid concentration levels were significantly higher in the hippocampi of group E and F rats treated with DHA compared with group C rats (P<0.05). Furthermore, DHA treatment alleviated the decrease in brain-derived neurotrophic factor levels (P<0.05), and superoxide dismutase (P<0.05) and glutathione peroxidase (P<0.05) activities induced by the administration of propofol. Additionally, DHA treatment decreased malondialdehyde levels in the hippocampi of rats (P<0.05). The aforementioned findings demonstrate that DHA was able to effectively improve learning and memory dysfunction induced by repeated propofol-induced anesthesia in young rats. This data suggests that DHA may be a potential candidate for further preclinical studies aimed at treating postoperative cognitive dysfunction.