The Effects of a Ketogenic Diet on Sensorimotor Function in a Thoracolumbar Mouse Spinal Cord Injury Model

Beta-Hydroxybutyrate Mitigates Sensorimotor and Cognitive Impairments in a Photothrombosis-Induced Ischemic Stroke in Mice

The consequences of stroke include cognitive deficits and sensorimotor disturbances, which are largely related to mitochondrial impairments in the brain. In this work, we have shown that the mimetic of the ketogenic diet beta-hydroxybutyrate (βHB) can improve neurological brain function in stroke. At 3 weeks after photothrombotic stroke, mice receiving βHB with drinking water before and after surgery recovered faster in terms of sensorimotor functions assessed by the string test and static rods and cognitive functions assessed by the Morris water maze. At the same time, the βHB-treated mice had lower expression of some markers of astrocyte activation and inflammation (Gfap, Il-1b, Tnf). We hypothesize that long-term administration of βHB promotes the activation of the nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) pathway, which leads to increased expression of antioxidant genes targeting mitochondria and genes involved in signaling pathways necessary for the maintenance of synaptic plasticity. βHB partially maintained mitochondrial DNA (mtDNA) integrity during the first days after photothrombosis. However, in the following three weeks, the number of mtDNA damages increased in all experimental groups, which coincided with a decrease in Ogg1 expression, which plays an important role in mtDNA repair. Thus, we can assume that βHB is not only an important metabolite that provides additional energy to brain tissue during recovery from stroke under conditions of mitochondrial damage but also an important signaling molecule that supports neuronal plasticity and reduces neuroinflammation.

Rodent Models of Spinal Cord Injury: From Pathology to Application

Spinal cord injury (SCI) often has devastating consequences for the patient's physical, mental and occupational health. At present, there is no effective treatment for SCI, and appropriate animal models are very important for studying the pathological manifestations, injury mechanisms, and corresponding treatment. However, the pathological changes in each injury model are different, which creates difficulties in selecting appropriate models for different research purposes. In this article, we analyze various SCI models and introduce their pathological features, including inflammation, glial scar formation, axon regeneration, ischemia-reperfusion injury, and oxidative stress, and evaluate the advantages and disadvantages of each model, which is convenient for selecting suitable models for different injury mechanisms to study therapeutic methods.

Cognitive profile of male mice exposed to a Ketogenic Diet

In recent years, nutritional interventions for different psychiatric diseases have gained increasing attention, such as the ketogenic diet (KD). This has led to positive effects in neurological disorders such as Parkinson's disease, addiction, autism or epilepsy. The neurobiological mechanisms through which these effects are induced and the effects in cognition still warrant investigation, and considering that other high-fat diets (HFD) can lead to cognitive disturbances that may affect the results achieved, the main aim of the present work was to evaluate the effects of a KD to determine whether it can induce such cognitive effects. A total of 30 OF1 male mice were employed to establish the behavioral profile of mice fed a KD by testing anxiety behavior (Elevated Plus Maze), locomotor activity (Open Field), learning (Hebb Williams Maze), and memory (Passive Avoidance Test). The results revealed that the KD did not affect locomotor activity, memory or hippocampal-dependent learning, as similar results were obtained with mice on a standard diet, albeit with increased anxiety behavior. We conclude that a KD is a promising nutritional approach to apply in research studies, given that it does not cause cognitive alterations.

Acute and chronic effects of oral administration of a medium-chain fatty acid, capric acid, on locomotor activity and anxiety-like and depression-related behaviors in adult male C57BL/6J mice

Aim

Capric acid (also known as decanoic acid or C10) is one of the fatty acids in the medium‐chain triglycerides (MCTs) commonly found in dietary fats. Although dietary treatment with MCTs is recently of great interest for the potential therapeutic effects on neuropsychiatric disorders, the effects of oral administration of C10 on behavior remain to be examined. This study investigated acute and chronic effects of oral administration of C10 on locomotor activity and anxiety‐like and depression‐related behaviors in adult male C57BL/6J mice.

Methods

To explore the acute effects of C10 administration, mice were subjected to a series of behavioral tests in the following order: light/dark transition, open field, elevated plus maze, Porsolt forced swim, and tail suspension tests, 30 minutes after oral gavage of either vehicle or C10 solution (30 mmol/kg dose in Experiment 1; 0.1, 0.3, 1.0, 3.0 mmol/kg doses in Experiment 2). Next, to examine chronic effects of C10, mice repeatedly administered with either vehicle or C10 solution (0.3, 3.0 mmol/kg doses per day, for 21 days, in Experiment 3) were subjected to behavioral tests without oral administration immediately before each test.

Results

The mice administrated with the high dose of C10 (30 mmol/kg) showed lower body weights, shorter distance traveled, and more anxiety‐like behavior than vehicle‐treated mice, and the results reached study‐wide statistical significance. The C10 administration at a lower dose of 0.3 mmol/kg had no significant effects on body weights and induced nominally significantly longer distance traveled than vehicle administration. Repeated administration of C10 at a dose of 3.0 mmol/kg for more than 21 days caused lower body weights and decreased depression‐related behavior, although the behavioral differences did not reach study‐wide significance.

Conclusions

Although these results suggest dose‐dependent effects of oral administration of capric acid on locomotor activity and anxiety‐like and depression‐related behaviors, further study will be needed to replicate the findings and explore the underlying brain mechanisms.

Repeated oral administration of the medium‐chain fatty acid, capric acid, decreased depression‐related behavior in C57BL/6J mice. This study suggests that capric acid exerts an antidepressant effect.

The Role of Dietary Nutrients in Peripheral Nerve Regeneration

Peripheral nerves are highly susceptible to injuries induced from everyday activities such as falling or work and sport accidents as well as more severe incidents such as car and motorcycle accidents. Many efforts have been made to improve nerve regeneration, but a satisfactory outcome is still unachieved, highlighting the need for easy to apply supportive strategies for stimulating nerve growth and functional recovery. Recent focus has been made on the effect of the consumed diet and its relation to healthy and well-functioning body systems. Normally, a balanced, healthy daily diet should provide our body with all the needed nutritional elements for maintaining correct function. The health of the central and peripheral nervous system is largely dependent on balanced nutrients supply. While already addressed in many reviews with different focus, we comprehensively review here the possible role of different nutrients in maintaining a healthy peripheral nervous system and their possible role in supporting the process of peripheral nerve regeneration. In fact, many dietary supplements have already demonstrated an important role in peripheral nerve development and regeneration; thus, a tailored dietary plan supplied to a patient following nerve injury could play a non-negotiable role in accelerating and promoting the process of nerve regeneration.

Systematic Review - Neuroprotection of ketosis in acute injury of the mammalian central nervous system: A meta-analysis

To evaluate the neuroprotection exerted by ketosis against acute damage of the mammalian central nervous system (CNS). Search engines were interrogated to identify experimental studies comparing the mitigating effect of ketosis (intervention) versus non-ketosis (control) on acute CNS damage. Primary endpoint was a reduction in mortality. Secondary endpoints were a reduction in neuronal damage and dysfunction, and an 'aggregated advantage' (composite of all primary and secondary endpoints). Hedges' g was the effect measure. Subgroup analyses evaluated the modulatory effect of age, insult type, and injury site. Meta-regression evaluated timing, type, and magnitude of intervention as predictors of neuroprotection. The selected publications were 49 experimental murine studies (period 1979-2020). The intervention reduced mortality (g 2.45, SE 0.48, p < .01), neuronal damage (g 1.96, SE 0.23, p < .01) and dysfunction (g 0.99, SE 0.10, p < .01). Reduction of mortality was particularly pronounced in the adult subgroup (g 2.71, SE 0.57, p < .01). The aggregated advantage of ketosis was stronger in the pediatric (g 3.98, SE 0.71, p < .01), brain (g 1.96, SE 0.18, p < .01), and ischemic insult (g 2.20, SE 0.23, p < .01) subgroups. Only the magnitude of intervention was a predictor of neuroprotection (g 0.07, SE 0.03, p 0.01 per every mmol/L increase in ketone levels). Ketosis exerts a potent neuroprotection against acute damage to the mammalian CNS in terms of reduction of mortality, of neuronal damage and dysfunction. Hematic levels of ketones are directly proportional to the effect size of neuroprotection.

Nerve injury and repair in a ketogenic milieu: A systematic review of traumatic injuries to the spinal cord and peripheral nervous tissue

Dietary interventions such as intermittent fasting and the ketogenic diet have demonstrated neuroprotective effects in various models of neurological insult. However, there has been a lack of evaluation of these interventions from a surgical perspective despite their potential to augment reparative processes that occur following nerve injury. Thus, we sought to analyze the effects of these dietary regimens on nerve regeneration and repair by critical appraisal of the literature. Following PRISMA guidelines, a systematic review was performed to identify studies published between 1950 and 2020 that examined the impact of either the ketogenic diet or intermittent fasting on traumatic injuries to the spinal cord or peripheral nerves. Study characteristics and outcomes were analyzed for each included article. A total of 1,890 articles were reviewed, of which 11 studies met inclusion criteria. Each of these articles was then assessed based on a variety of qualitative parameters, including type of injury, diet composition, timing, duration, and outcome. In total, seven articles examined the ketogenic diet, while four examined intermittent fasting. Only three studies examined peripheral nerves. Neuroprotective effects manifested as either improved histological or functional benefits in most of the included studies. Overall, we conclude that intermittent fasting and the ketogenic diet may promote neuroprotection and facilitate the regeneration and repair of nerve fibers following injury; however, lack of consistency between the studies in terms of animal models, diet compositions, and timing of dietary interventions preclude synthesis of their outcomes as a whole.