Cortical spreading depression produces a neuroprotective effect activating mitochondrial uncoupling protein-5

Dexamethasone-Enhanced Continuous Online Microdialysis for Neuromonitoring of O2 after Brain Injury

Traumatic brain injury (TBI) is a major public health crisis in many regions of the world. Severe TBI may cause a primary brain lesion with a surrounding penumbra of tissue that is vulnerable to secondary injury. Secondary injury presents as progressive expansion of the lesion, possibly leading to severe disability, a persistent vegetive state, or death. Real time neuromonitoring to detect and monitor secondary injury is urgently needed. Dexamethasone-enhanced continuous online microdialysis (Dex-enhanced coMD) is an emerging paradigm for chronic neuromonitoring after brain injury. The present study employed Dex-enhanced coMD to monitor brain K⁺ and O₂ during manually induced spreading depolarization in the cortex of anesthetized rats and after controlled cortical impact, a widely used rodent model of TBI, in behaving rats. Consistent with prior reports on glucose, O₂ exhibited a variety of responses to spreading depolarization and a prolonged, essentially permanent decline in the days after controlled cortical impact. These findings confirm that Dex-enhanced coMD delivers valuable information regarding the impact of spreading depolarization and controlled cortical impact on O₂ levels in the rat cortex.

Fructose supplementation shifts rat brain metabolism in experimental migraine

AIMS

We have previously demonstrated that fructose supplementation (FS), given in a scheme used for inducing metabolic syndrome (MS), elicited pain relief in the nitroglycerin (NTG)-elicited rat migraine model. Herein, we evaluated whether FS could reestablish the impaired metabolic pathways in NTG-injected rats.

MAIN METHODS

Male Wistar rats (N=40) were divided into two groups for receiving 10-% FS or tap water. After 45 days, they were subdivided into NTG-injected (10mg/kg; 15 days) or controls. After the fourth NTG injection, ¹⁸F-fluorodeoxyglucose ([¹⁸F] FDG) micro-PET scanning was accomplished. The day after, euthanasia was performed, and blood was collected for glycemia and LDH analysis. The levels of energy molecules, TBARS, PGC-1α, and MCTS1 were evaluated in the brain cortices. The activated satellite glial cells (SGC) were assessed in the trigeminal ganglion (TG).

KEY FINDINGS

There were no variations of glycemia or LDH serum levels. NTG-injected rats showed a significant increase in glucose uptake in the hypothalamus (HT) vs. NTG-free rats. The FS-NTG group showed increased metabolism in the superior colliculus (SC) vs. the NTG group. Moreover, the glucose uptake was amplified in the inferior colliculus (IC) of the FS-NTG vs. FS group. The cortical inosine levels were significantly higher in FS-NTG rats vs. NTG or FS groups, with no changes in TBARS or MCTS1 levels, despite a minor decrease of PGC1-α contents in the FS+NTG group. Finally, there was a significant increase of activated SGC around TG in the FS-NTG rats.

SIGNIFICANCE

We provide novel evidence linking nutrition and metabolism with migraine.

Heart Rate Variability and Sympathetic Activity Is Modulated by Very Low-Calorie Ketogenic Diet

Obesity is characterized by an energy imbalance and by the accumulation of visceral adipose tissue. The energy balance is controlled by a complex set of balanced physiological systems that provide hunger and satiety signals to the brain and regulate the body’s ability to consume energy. The central nervous system controls the metabolic state, influencing the activity of other systems and receiving information from them. Heart rate variability (HRV) is the natural variability of the heart rate in response to several factors. HRV is related to the interaction between the SNS and the parasympathetic. In the light of this evidence, the aim of this study is to investigate the possible effects of the two different dietary regimens such as very low-calorie ketogenic diet (VLCKD) vs. low caloric diet (LCD), on the functions of the nervous system, with particular attention to the autonomous control of heart rate variability (HRV). A total of 26 obese subjects underwent diet therapy in order to reduce body weight; they were also randomly divided into two groups: the VLCKD group and the LCD group. Our results showed that in both groups, there is a reduction in heart rate as an indicator of sympathetic activity; we found a statistically significant variation only in the VLCKD group. Therefore, this study supports the notion that the sympathovagal balance can be modulated by a specific diet, but further studies are needed to clarify the molecular pathway undergoing this modulation.

Effects of Mixed of a Ketogenic Diet in Overweight and Obese Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a commonly occurring endocrine disorder characterized by hirsutism, anovulation, and polycystic ovaries. Often comorbid with insulin resistance, dyslipidemia, and obesity, it also carries significant risk for the development of cardiovascular and metabolic sequelae, including diabetes and metabolic syndrome. The relationship between central obesity and the development of insulin resistance is widely verified. Adipose tissue excess and the coexistent dysregulation of adipocyte functions directly contribute to the pathogenesis of the metabolic complications observed in women with PCOS. In the light of these evidence, the most therapeutic option prescribed to obese women with PCOS, regardless of the phenotype e from the severity of clinical expression, is lifestyle correction by diet and physical activity. The aim of this study is to evaluate the beneficial effects of ketogenic diet in 17 obese women with PCOS. Our results showed that the ketogenic diet inducing therapeutic ketosis, improves the anthropometric and many biochemical parameters such as LH, FSH, SHBG, insulin sensitivity and HOMA index. In addition, it induces a reduction in androgenic production, whereas the contextual reduction of fat mass reduced the acyclic production of estrogens deriving from the aromatization in the adipose tissue of the androgenic excess, with an improvement of the LH/FSH ratio. This is the first study on the effects of the ketogenic diet on PCOS, however, further studies are needed to elucidate the mechanism underlying ketogenic diet effects.

Mitochondrial Uncoupling Proteins (UCPs) as Key Modulators of ROS Homeostasis: A Crosstalk between Diabesity and Male Infertility?

Uncoupling proteins (UCPs) are transmembrane proteins members of the mitochondrial anion transporter family present in the mitochondrial inner membrane. Currently, six homologs have been identified (UCP1-6) in mammals, with ubiquitous tissue distribution and multiple physiological functions. UCPs are regulators of key events for cellular bioenergetic metabolism, such as membrane potential, metabolic efficiency, and energy dissipation also functioning as pivotal modulators of ROS production and general cellular redox state. UCPs can act as proton channels, leading to proton re-entry the mitochondrial matrix from the intermembrane space and thus collapsing the proton gradient and decreasing the membrane potential. Each homolog exhibits its specific functions, from thermogenesis to regulation of ROS production. The expression and function of UCPs are intimately linked to diabesity, with their dysregulation/dysfunction not only associated to diabesity onset, but also by exacerbating oxidative stress-related damage. Male infertility is one of the most overlooked diabesity-related comorbidities, where high oxidative stress takes a major role. In this review, we discuss in detail the expression and function of the different UCP homologs. In addition, the role of UCPs as key regulators of ROS production and redox homeostasis, as well as their influence on the pathophysiology of diabesity and potential role on diabesity-induced male infertility is debated.

Frequency selective neuronal modulation triggers spreading depolarizations in the rat endothelin-1 model of stroke

Ischemia is one of the most common causes of acquired brain injury. Central to its noxious sequelae are spreading depolarizations (SDs), waves of persistent depolarizations which start at the location of the flow obstruction and expand outwards leading to excitotoxic damage. The majority of acute stage of stroke studies to date have focused on the phenomenology of SDs and their association with brain damage. In the current work, we investigated the role of peri-injection zone pyramidal neurons in triggering SDs by optogenetic stimulation in an endothelin-1 rat model of focal ischemia. Our concurrent two photon fluorescence microscopy data and local field potential recordings indicated that a ≥ 60% drop in cortical arteriolar red blood cell velocity was associated with SDs at the ET-1 injection site. SDs were also observed in the peri-injection zone, which subsequently exhibited elevated neuronal activity in the low-frequency bands. Critically, SDs were triggered by low- but not high-frequency optogenetic stimulation of peri-injection zone pyramidal neurons. Our findings depict a complex etiology of SDs post focal ischemia and reveal that effects of neuronal modulation exhibit spectral and spatial selectivity.

The Role of Very Low Calorie Ketogenic Diet in Sympathetic Activation through Cortisol Secretion in Male Obese Population

Adipose tissue is considered an endocrine organ, and its excess compromises the immune response and metabolism of hormones and nutrients. Furthermore, the accumulation of visceral fat helps to increase the synthesis of cortisol. The hypothalamus-pituitary-adrenal (HPA) axis is a neuroendocrine system involved in maintaining homeostasis in humans under physiological conditions and stress, and cortisol is the main hormone of the HPA axis. It is known that a stress-induced diet and cortisol reactivity to acute stress factors may be related to dietary behavior. In obesity, to reduce visceral adipose tissue, caloric restriction is a valid strategy. In light of this fact, the aim of this study was to assess the effects of a commercial dietary ketosis program for weight loss on the sympathetic nervous system and HPA axis, through evaluation of salivary cortisol and GSR levels. Thirty obese subjects were recruited and assessed before and after 8 weeks of Very Low Calorie Ketogenic Diet (VLCKD) intervention to evaluate body composition and biochemical parameters. Salivary cortisol levels and GSR significantly decreased after dietary treatment; in addition, body composition and biochemical features were ameliorated. The VLCKD had a short-term positive effect on the SNS and HPA axes regulating salivary cortisol levels. Finally, the effects of the VLCKD on the SNS and HPA axis may lead to more individualized treatment strategies that integrate obesity and stress and support the usefulness of such therapeutic interventions in promoting the reduction of the individual disease burden.

Very Low-Calorie Ketogenic Diet Modulates the Autonomic Nervous System Activity through Salivary Amylase in Obese Population Subjects

In obesity, to reduce visceral adipose tissue (VAT), caloric restriction is a valid strategy. Salivary amylase is an enzyme that cleaves large starch carbohydrates molecules and its production is modulated by the central nervous system. In addition, heart rate variability (HRV) is simply a measure of the variation in time between each heartbeat. This variation is controlled by the autonomic nervous system. In the light of this evidence, the aim of this study is to characterize the effect of a very low-calorie ketogenic diet (VLCKD) on the autonomic nervous system in obese patients. Twenty subjects affected by obesity were recruited before and after 8 weeks of VLCKD intervention to evaluate salivary amylase by the ELISA test and HRV analysis. These parameters significantly increased after dietary treatment, and positively correlate to each other. VLCKD exerts a positive effect on salivary amylase and HRV, ameliorating body composition and biochemical features. In brief, this dietary intervention improves the autonomic nervous system activity. This is the first study about the effects of VLCKD upon the autonomic nervous system, but further studies are needed to elucidate the mechanism undergone VLCKD effects.

Transcranial Magnetic Stimulation as a Tool to Investigate Motor Cortex Excitability in Sport

Transcranial magnetic stimulation, since its introduction in 1985, has brought important innovations to the study of cortical excitability as it is a non-invasive method and, therefore, can be used both in healthy and sick subjects. Since the introduction of this cortical stimulation technique, it has been possible to deepen the neurophysiological aspects of motor activation and control. In this narrative review, we want to provide a brief overview regarding TMS as a tool to investigate changes in cortex excitability in athletes and highlight how this tool can be used to investigate the acute and chronic responses of the motor cortex in sport science. The parameters that could be used for the evaluation of cortical excitability and the relative relationship with motor coordination and muscle fatigue, will be also analyzed. Repetitive physical training is generally considered as a principal strategy for acquiring a motor skill, and this process can elicit cortical motor representational changes referred to as use-dependent plasticity. In training settings, physical practice combined with the observation of target movements can enhance cortical excitability and facilitate the process of learning. The data to date suggest that TMS is a valid technique to investigate the changes in motor cortex excitability in trained and untrained subjects. Recently, interest in the possible ergogenic effect of non-invasive brain stimulation in sport is growing and therefore in the future it could be useful to conduct new experiments to evaluate the impact on learning and motor performance of these techniques.

Analysis of a New Work-Related Stress Assessment Tool

Background:

Work-related stress is a relevant phenomenon in terms of health and safety at work, as occupational distress has a negative impact on individual and organisational well-being. It is a complex and multifactorial phenomenon, whose evaluation must be carried out through a specific and adequate methodology.

Objective:

This work aims to identify versatile tools that can quickly provide reliable measures of work distress. It analyzes the proposal elaborated by the “Comitato Unico di Garanzia per le Pari Opportunità, la Valorizzazione del Benessere di chi lavora e contro le Discriminazioni” of Rome, i.e. the tool “Valutazione è prevenzione, Sicurezza è partecipazione”.

Methods:

A study was carried out on a sample of 474 employees of the Neapolitan Judicial Offices, who were given a standardized questionnaire to investigate the stress, associated with the proposal of the Comitato Unico di Garanzia.

Results:

From the elaboration of the results, it emerges that the conditions of working wellbeing are linked to two main factors related to the perception of workers both of physical-environmental and organisational-relational aspects. In particular, it emerged that the new assessment tool, consisting of a small number of items, contributes to the detection of work stress, so it is necessary to deepen through future research the contribution that this tool can offer to the survey on work-related stress.

Conclusion:

Having highlighted two factors that significantly saturate the presence of a working discomfort, through an agile tool, allows us to plan a new research path, which can approach the complexity of the phenomenon through the methods of deep learning.

Is there a timing for sensitivity to acute cerebral ischemia in migraine patients?

BACKGROUND

Migraine may be a factor of increased cerebral sensitivity to ischemia. Previous studies were conducted within 6 to 72 after stroke onset. We aimed to determine if an accelerated infarct growth exists in migraine patients within the first 4.5 h.

METHOD

A retrospective case-control study was conducted where all patients admitted for acute stroke started <4.5 h before and who underwent perfusion CT were assessed. The hypoperfusion and necrosis volumes on initial CT perfusion were analyzed, as well as the final infarct volume on MRI performed within 72 h after admission. A no-mismatch pattern was defined as a ratio necrosis/hypoperfusion volume > 83%.

RESULTS

24 patients with personal history of migraine were identified, 8 of them with aura. The control cohort included 51 patients. No difference was found between groups in terms of demographics, initial severity or outcome or presumed cause of stroke. Mean time to CT scan was 125 min in migraine patients and 127 min in the control group. A no-mismatch pattern was equally found in migraine patients and controls, even after adjustment for age, sex and presence of proximal occlusion (p = .22). The final infarct volume was also similar in both groups.

CONCLUSIONS

Migraine patients did not display more no-mismatch pattern than controls within the 4.5 h of stroke onset. This deviates from previous studies and may be due to our earlier time from stroke onset to CT scan. A history of migraine may lead to malignant progression of ischemia but occurring only after several hours.

The metabolic face of migraine - from pathophysiology to treatment

Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.

Spreading Depolarization Waves in Neurological Diseases: A Short Review about its Pathophysiology and Clinical Relevance

Lesion growth following acutely injured brain tissue after stroke, subarachnoid hemorrhage and traumatic brain injury is an important issue and a new target area for promising therapeutic interventions. Spreading depolarization or peri-lesion depolarization waves were demonstrated as one of the significant contributors of continued lesion growth. In this short review, we discuss the pathophysiology for SD forming events and try to list findings detected in neurological disorders like migraine, stroke, subarachnoid hemorrhage and traumatic brain injury in both human as well as experimental studies. Pharmacological and non-pharmacological treatment strategies are highlighted and future directions and research limitations are discussed.

Ketamine reduces deleterious consequences of spreading depolarizations

Recent work has implicated spreading depolarization (SD) as a key contributor the progression of acute brain injuries, however development of interventions selectively targeting SD has lagged behind. Initial clinical intervention efforts have focused on observations that relatively high doses of the sedative agent ketamine can completely suppress SD. However, blocking propagation of SD could theoretically prevent beneficial effects of SD in surrounding brain regions. Selective targeting of deleterious consequences of SD (rather than abolition) could be a useful adjunct approach, and be achieved with lower ketamine concentrations. We utilized a brain slice model to test whether deleterious consequences of SD could be prevented by ketamine, using concentrations that did not prevent the initiation and propagation of SD. Studies were conducted using murine brain slices, with focal KCl as an SD stimulus. Consequences of SD were assessed with electrophysiological and imaging measures of ionic and synaptic recovery. Under control conditions, ketamine (up to 30 μM) did not prevent SD, but significantly reduced neuronal Ca2+ loading and the duration of associated extracellular potential shifts. Recovery of postsynaptic potentials after SD was also significantly accelerated. When SD was evoked on a background of mild metabolic compromise, neuronal recovery was substantially impaired. Under compromised conditions, the same concentrations of ketamine reduced ionic and metabolic loading during SD, sufficient to preserve functional recovery after repetitive SDs. These results suggest that lower concentrations of ketamine could be utilized to prevent damaging consequences of SD, while not blocking them outright and thereby preserving potentially protective effects of SD.

Harnessing migraines for neural regeneration

The success of naturalistic or therapeutic neuroregeneration likely depends on an internal milieu that facilitates the survival, proliferation, migration, and differentiation of stem cells and their assimilation into neural networks. Migraine attacks are an integrated sequence of physiological processes that may protect the brain from oxidative stress by releasing growth factors, suppressing apoptosis, stimulating neurogenesis, encouraging mitochondrial biogenesis, reducing the production of oxidants, and upregulating antioxidant defenses. Thus, the migraine attack may constitute a physiologic environment conducive to stem cells. In this paper, key components of migraine are reviewed – neurogenic inflammation with release of calcitonin gene-related peptide (CGRP) and substance P, plasma protein extravasation, platelet activation, release of serotonin by platelets and likely by the dorsal raphe nucleus, activation of endothelial nitric oxide synthase (eNOS), production of brain-derived neurotrophic factor (BDNF) and, in migraine aura, cortical spreading depression – along with their potential neurorestorative aspects. The possibility is considered of using these components to facilitate successful stem cell transplantation. Potential methods for doing so are discussed, including chemical stimulation of the TRPA1 ion channel, conjoint activation of a subset of migraine components, invasive and noninvasive deep brain stimulation of the dorsal raphe nucleus, transcranial focused ultrasound, and stimulation of the Zusanli (ST36) acupuncture point.

Primary Motor Cortex Excitability in Karate Athletes: A Transcranial Magnetic Stimulation Study

Purpose: The mechanisms involved in the coordination of muscle activity are not completely known: to investigate adaptive changes in human motor cortex Transcranial magnetic stimulation (TMS) was often used. The sport models are frequently used to study how the training may affect the corticospinal system excitability: Karate represents a valuable sport model for this kind of investigations for its high levels of coordination required to athletes. This study was aimed at examining possible changes in the resting motor threshold (rMT) and in the corticospinal response in karate athletes, and at determining whether athletes are characterized by a specific value of rMT.

Methods: We recruited 25 right-handed young karate athletes and 25 matched non-athletes. TMS was applied to primary motor cortex (M1). Motor evoked potential (MEP) were recorded by two electrodes placed above the first dorsal interosseous (FDI) muscle. We considered MEP latencies and amplitudes at rMT, 110% of rMT, and 120% of rMT.

Results: The two groups were similar for age (p > 0.05), height (p > 0.05) and body mass (p > 0.05). The TMS had a 70-mm figure-of-eight coil and a maximum output of 2.2 T, placed over the left motor cortex. During the stimulation, a mechanical arm kept the coil tangential to the scalp, with the handle at 45° respect to the midline. The SofTaxic navigator system (E.M.S. Italy, www.emsmedical.net) was used in order to correctly identifying and repeating the stimulation for every subject. Compared to non-athletes, athletes showed a lower resting motor threshold (p < 0.001). Furthermore, athletes had a lower MEP latency (p < 0.001) and a higher MEP amplitude (p < 0.001) compared to non-athletes. Moreover, a ROC curve for rMT was found significant (area: 0.907; sensitivity 84%, specificity 76%).

Conclusions: As the main finding, the present study showed significant differences in cortical excitability between athletes and non-athletes. The training can improve cortical excitability inducing athletes' modifications, as demonstrated in rMT and MEP values. These finding support the hypothesis that the sport practice determines specific brain organizations in relationship with the sport challenges.

Role of Autonomic Nervous System and Orexinergic System on Adipose Tissue

Adipose tissue, defined as white adipose tissue (WAT) and brown adipose tissue (BAT), is a biological caloric reservoir; in response to over-nutrition it expands and, in response to energy deficit, it releases lipids. The WAT primarily stores energy as triglycerides, whereas BAT dissipates chemical energy as heat. In mammals, the BAT is a key site for heat production and an attractive target to promote weight loss. The autonomic nervous system (ANS) exerts a direct control at the cellular and molecular levels in adiposity. The sympathetic nervous system (SNS) provides a complex homeostatic control to specifically coordinate function and crosstalk of both fat pads, as indicated by the increase of the sympathetic outflow to BAT, in response to cold and high-fat diet, but also by the increase or decrease of the sympathetic outflow to selected WAT depots, in response to different lipolytic requirements of these two conditions. More recently, a role has been attributed to the parasympathetic nervous system (PNS) in modulating both adipose tissue insulin-mediated glucose uptake and fatty free acid (FFA) metabolism in an anabolic way and its endocrine function. The regulation of adipose tissue is unlikely to be limited to the autonomic control, since a number of signaling cytokines and neuropeptides play an important role, as well. In this review, we report some experimental evidences about the role played by both the ANS and orexins into different fat pads, related to food intake and energy expenditure, with a special emphasis on body weight status and fat mass (FM) content.

Abnormal mitochondrial dynamics and impaired mitochondrial biogenesis in trigeminal ganglion neurons in a rat model of migraine

Accumulating evidence has demonstrated a possible role of mitochondrial dysfunction in migraine pathophysiology. Migraine sufferers exhibit impaired metabolic capacity, with an increased formation of reactive oxygen species (ROS). Mitochondrial dynamics and mitochondrial biogenesis are key processes regulating mitochondrial homeostasis. The aim of this study was to explore the alterations of mitochondrial regulatory networks in a rat model of migraine induced by repeated dural stimulation with inflammatory soup (IS). Ultrastructural, protein, gene and mitochondrial DNA analysis were applied to assess mitochondrial dynamics and biogenesis in trigeminal ganglion (TG) neurons. Mitochondria in TG neurons exhibited small and fragmented morphology after repeated dural stimulation. Further investigations showed that mitochondrial fission protein dynamin-related protein 1 (Drp1) was increased while mitochondrial fusion protein Mitofusin1 (Mfn1) was reduced in TG neurons. In addition, our results also presented that mitochondrial DNA copy number in TG neurons was reduced significantly, accompanied by alterations in mRNA and protein levels of regulatory factors related to mitochondrial biogenesis including peroxisome proliferator-activated receptor-gamma coactivator-1a (PGC-1α) and its downstream regulators in TG neurons in the IS-induced migraine model. These findings suggest that the mitochondrial dynamic regulatory networks are maladjusted in TG neurons in a rat model of migraine. Regulation of mitochondrial dynamics and biogenesis signaling may indicate a new mitochondria-targeted therapeutic strategy for migraine.