Exercise increases the level of plasma orexin A in humans

A comprehensive review on the impact of polyphenol supplementation and exercise on depression and brain function parameters

The objective of this review study is to examine the combined antidepressant effects of exercise and polyphenol supplementation, with a focus on specific polyphenolic compounds such as crocin, curcumin, and quercetin, as well as different forms of physical exercise, including aerobic and resistance training. The research examines how these interventions influence depressive-like behaviors, cognitive function, and neurochemical markers in animal models and human participants. The findings demonstrate that both exercise and polyphenols independently contribute to mood enhancement, reduced anxiety, and improved cognitive function through mechanisms such as neurogenesis, neurotransmitter modulation, and anti-inflammatory effects. Notably, the combined interventions showed a synergistic effect, providing more significant benefits in reducing symptoms of depression and anxiety, enhancing cognitive performance, and supporting overall mental well-being. These results suggest that integrating exercise and polyphenol supplementation could be a promising non-pharmacological approach to managing depression and related disorders.

Involvement of D1 dopamine receptor in the nucleus of the solitary tract of rats in stress-induced hypertension and exercise

OBJECTIVE

Chronic stress can cause hypertension, whereas daily exercise promotes healthy well being through destressing. Although the nucleus of the solitary tract (NTS) is involved in the development of hypertension, the molecular and physiological mechanisms of stress and exercise remain unclear. In this study, we tested whether gene expression in the NTS is altered by stress and daily exercise and whether this is involved in cardiovascular regulation.

METHODS

We have performed RT 2 Profiler PCR arrays targeting a panel of neurotransmitter receptor genes in the NTS of Wistar rats subjected to chronic restraint stress (1 h a day over 3 weeks) with or without voluntary wheel exercise. We also performed immunohistochemistry to determine whether the identified molecules were expressed at the protein level. Additionally, microinjection studies in anesthetized rats were performed to examine whether validated molecules exhibit physiological roles in cardiovascular regulation of the NTS.

RESULTS

We observed that blood pressure was significantly increased by stress and the increase was suppressed by exercise. Using PCR analysis, we determined that the expression levels of four genes in the NTS, including the dopamine receptor D1 gene ( Drd1 ), were significantly affected by stress and suppressed by exercise. We also examined dopamine D1 receptor (D1R) expression in NTS neurons and found significantly greater expression in the stressed than nonstressed animals. Furthermore, the microinjection of a D1R agonist into the NTS in anesthetized rats induced hypotensive effects.

CONCLUSION

These results suggest that NTS D1R plays a role in the counteracting processes of stress-induced hypertension.

Possible role of exercise therapy on depression: Effector neurotransmitters as key players

About 280 million people suffer from depression as the most common neurological disorder and the most common cause of death worldwide. Exercise with serotonin released in the brain by the 5-HT3-IGF-1 mechanism can lead to antidepressant effects. Swimming exercise has antidepressant effects by increasing the sensitivity of serotonin 5-HT2 receptors and postsynaptic 5-HT1A receptors, increasing 5-HT and 5HIAA levels, increasing TPH and serotonin, and decreasing inflammatory levels of IFN-γ and TNF-α. Anaerobic and aerobic exercises increase beta-endorphin, enkephalin, and dynorphin and have antidepressant effects. Exercise by increasing dopamine, D1R, and D2R leads to the expression of BDNF and activation of TrkB and has antidepressant behavior. Exercise leads to a significant increase in GABAAR (γ2 and α2 subunits) and reduces neurodegenerative disorders caused by GABA imbalance through anti-inflammatory pathways. By increasing glutamate and PGC1α and reducing glutamatergic neurotoxicity, exercise enhances neurogenesis and synaptogenesis and prevents neurodegeneration and the onset of depression. Irisin release during exercise shows an important role in depression by increasing dopamine, BDNF, NGF, and IGF-1 and decreasing inflammatory mediators such as IL-6 and IL-1β. In addition, exercise-induced orexin and NPY can increase hippocampal neurogenesis and relieve depression. After exercise, the tryptophan to large neutral amino acids (TRP/LNAA) ratio and the tryptophan to branched-chain amino acids (BCAA) ratio increase, which may have antidepressant effects. The expression of M5 receptor and nAChR α7 increases after exercise and significantly increases dopamine and acetylcholine and ameliorates depression. It appears that during exercise, muscarinic receptors can reduce depression through dopamine in the absence of acetylcholine. Therefore, exercise can be used to reduce depression by affecting neurotransmitters, neuromodulators, cytokines, and/or neurotrophins.

The potential role of the orexin system in premenstrual syndrome

Premenstrual syndrome (PMS) occurs recurrently during the luteal phase of a woman's menstrual cycle and disappears after menstruation ends. It is characterized by abnormal changes in both the body and mood, and in certain cases, severe disruptions in daily life and even suicidal tendencies. Current drugs for treating PMS, such as selective serotonin reuptake inhibitors, do not yield satisfactory results. Orexin, a neuropeptide produced in the lateral hypothalamus, is garnering attention in the treatment of neurological disorders and is believed to modulate the symptoms of PMS. This paper reviews the advancements in research on sleep disturbances, mood changes, and cognitive impairment caused by PMS, and suggests potential pathways for orexin to address these symptoms. Furthermore, it delves into the role of orexin in the molecular mechanisms underlying PMS. Orexin regulates steroid hormones, and the cyclic fluctuations of estrogen and progesterone play a crucial role in the pathogenesis of PMS. Additionally, orexin also modulates the gamma-aminobutyric acid (GABA) system and the inflammatory response involved in coordinating the mechanism of PMS. Unraveling the role of orexin in the pathogenesis of PMS will not only aid in understanding the etiology of PMS but also hold implications for orexin as a novel target for treating PMS.

Cellular and Molecular Regulation of Exercise-A Neuronal Perspective

The beneficial effects of exercise on the proper functioning of the body have been firmly established. Multi-systemic metabolic regulation of exercise is the consequence of multitudinous changes that occur at the cellular level. The exercise responsome comprises all molecular entities including exerkines, miRNA species, growth factors, signaling proteins that are elevated and activated by physical exercise. Exerkines are secretory molecules released by organs such as skeletal muscle, adipose tissue, liver, and gut as a function of acute/chronic exercise. Exerkines such as FNDC5/irisin, Cathepsin B, Adiponectin, and IL-6 circulate through the bloodstream, cross the blood-brain barrier, and modulate the expression of important signaling molecules such as AMPK, SIRT1, PGC1α, BDNF, IGF-1, and VEGF which further contribute to improved energy metabolism, glucose homeostasis, insulin sensitivity, neurogenesis, synaptic plasticity, and overall well-being of the body and brain. These molecules are also responsible for neuroprotective adaptations that exercise confers on the brain and potentially ameliorate neurodegeneration. This review aims to detail important cellular and molecular species that directly or indirectly mediate exercise-induced benefits in the body, with an emphasis on the central nervous system.

Internal and external modulation factors of the orexin system (REVIEW)

Orexin-A and -B (identical to hypocretin-1 and -2) are neuropeptides synthesized in the lateral hypothalamus and perifornical area, and orexin neurons project their axon terminals broadly throughout the entire central nervous system (CNS). The activity of orexins is mediated by two specific G protein-coupled receptors (GPCRs), termed orexin type1 receptor (OX1R) and orexin type2 receptor (OX2R). The orexin system plays a relevant role in various physiological functions, including arousal, feeding, reward, and thermogenesis, and is key to human health. Orexin neurons receive various signals related to environmental, physiological, and emotional stimuli. Previous studies have reported that several neurotransmitters and neuromodulators influence the activation or inhibition of orexin neuron activity. In this review, we summarize the modulating factors of orexin neurons in the sleep/wake rhythm and feeding behavior, particularly in the context of the modulation of appetite, body fluids, and circadian signaling. We also describe the effects of life activity, behavior, and diet on the orexin system. Some studies have observed phenomena that have been verified in animal experiments, revealing the detailed mechanism and neural pathway, while their applications to humans is expected in future research.

Dual Cannabinoid and Orexin Regulation of Anhedonic Behaviour Caused by Prolonged Restraint Stress

The endocannabinoid and orexin systems share many biological functions, including wakefulness, stress response, reward processing, and mood. While these systems work against one another with respect to arousal, chronic stress-induced downregulation of both systems often leads to anhedonia or the inability to experience pleasure from natural rewards. In the current study, a 24 h restraint stress test (24 h RST) reduced sucrose preference in adult male and female C57BL/6 mice. Prior to the stressor, subsets of mice were intraperitoneally administered cannabinoid and orexin receptor agonists, antagonists, and combinations of these drugs. Restraint mice that received the cannabinoid receptor type 1 (CB1R) antagonist SR141716A, orexin receptor type 2 (OX2R) agonist YNT-185, and the combination of SR141716A and YNT-185, exhibited less anhedonia compared to vehicle/control mice. Thus, the 24 h RST likely decreased orexin signaling, which was then restored by YNT-185. Receptor colocalization analysis throughout mesocorticolimbic brain regions revealed increased CB1R-OX1R colocalization from SR141716A and YNT-185 treatments. Although a previous study from our group showed additive cataleptic effects between CP55,940 and the dual orexin receptor antagonist (TCS-1102), the opposite combination of pharmacological agents proved additive for sucrose preference. Taken together, these results reveal more of the complex interactions between the endocannabinoid and orexin systems.

The molecular signaling of exercise and obesity in the microbiota-gut-brain axis

Obesity is one of the major pandemics of the 21st century. Due to its multifactorial etiology, its treatment requires several actions, including dietary intervention and physical exercise. Excessive fat accumulation leads to several health problems involving alteration in the gut-microbiota-brain axis. This axis is characterized by multiple biological systems generating a network that allows bidirectional communication between intestinal bacteria and brain. This mutual communication maintains the homeostasis of the gastrointestinal, central nervous and microbial systems of animals. Moreover, this axis involves inflammatory, neural, and endocrine mechanisms, contributes to obesity pathogenesis. The axis also acts in appetite and satiety control and synthesizing hormones that participate in gastrointestinal functions. Exercise is a nonpharmacologic agent commonly used to prevent and treat obesity and other chronic degenerative diseases. Besides increasing energy expenditure, exercise induces the synthesis and liberation of several muscle-derived myokines and neuroendocrine peptides such as neuropeptide Y, peptide YY, ghrelin, and leptin, which act directly on the gut-microbiota-brain axis. Thus, exercise may serve as a rebalancing agent of the gut-microbiota-brain axis under the stimulus of chronic low-grade inflammation induced by obesity. So far, there is little evidence of modification of the gut-brain axis as a whole, and this narrative review aims to address the molecular pathways through which exercise may act in the context of disorders of the gut-brain axis due to obesity.

Exerkines and long-term synaptic potentiation: Mechanisms of exercise-induced neuroplasticity

Physical exercise may improve cognitive function by modulating molecular and cellular mechanisms within the brain. We propose that the facilitation of long-term synaptic potentiation (LTP)-related pathways, by products induced by physical exercise (i.e., exerkines), is a crucial aspect of the exercise-effect on the brain. This review summarizes synaptic pathways that are activated by exerkines and may potentiate LTP. For a total of 16 exerkines, we indicated how blood and brain exerkine levels are altered depending on the type of physical exercise (i.e., cardiovascular or resistance exercise) and how they respond to a single bout (i.e., acute exercise) or multiple bouts of physical exercise (i.e., chronic exercise). This information may be used for designing individualized physical exercise programs. Finally, this review may serve to direct future research towards fundamental gaps in our current knowledge regarding the biophysical interactions between muscle activity and the brain at both cellular and system levels.

Correlation of Orexin-A and brain-derived neurotrophic factor levels in metabolic syndrome and cognitive impairment in schizophrenia treated with clozapine

Orexin-A and brain-derived neurotrophic factor (BDNF) are implicated in regulating metabolic syndrome (MetS) and cognitive impairment of schizophrenia. However, the associations among them remains unclear. Here, we aimed to investigate the relationship between Orexin-A levels, BDNF, MetS, clinical symptom profile, and cognitive function in schizophrenia patients following long-term clozapine treatment. We measured Orexin-A and BDNF levels in 140 schizophrenia patients with and without MetS. We assessed clinical symptoms on the Positive and Negative Syndrome Scale and cognitive function by the assessment of Neuropsychological Status (RBANS), and examined their associations with Orexin-A. Patients with MetS had significantly lower Orexin-A levels and higher coding test, attention span and delayed retention in RBANS (P < 0.05). Correlation analysis showed that Orexin-A was associated with BDNF, TG, HDLC, PANSS active social avoidance and emotional withdrawal significantly. Besides, Orexin-A significantly interacted with BDNF for metabolic and cognitive profiles including waist circumference, delayed retention and list recognition. Logistic regression analysis showed that Orexin-A level (odds ratio [OR]= 0.380, 95% confidence interval [CI]: 0.151-0.952, P = 0.039) and total illness duration (OR = 0.932, 95% CI: 0.875-0.991, P = 0.025) were predictive variables of MetS. However, there was no significant relationship between Orexin-A and cognitive function after adjustment for age, sex and educational levels. Totally, a lower plasma Orexin-A level seems to be related to metabolic parameters more than cognitive profiles. The interaction of Orexin-A with BDNF may be partly responsible for worse MetS and better cognition of elderly schizophrenia, but the causal relationship needs further clarification.

Reviewing the role of the orexinergic system and stressors in modulating mood and reward-related behaviors

In this review study, we aimed to introduce the orexinergic system as an important signaling pathway involved in a variety of cognitive functions such as memory, motivation, and reward-related behaviors. This study focused on the role of orexinergic system in modulating reward-related behavior, with or without the presence of stressors. Cross-talk between the reward system and orexinergic signaling was also investigated, especially orexinergic signaling in the ventral tegmental area (VTA), the nucleus accumbens (NAc), and the hippocampus. Furthermore, we discussed the role of the orexinergic system in modulating mood states and mental illnesses such as depression, anxiety, panic, and posttraumatic stress disorder (PTSD). Here, we narrowed down our focus on the orexinergic signaling in three brain regions: the VTA, NAc, and the hippocampus (CA1 region and dentate gyrus) for their prominent role in reward-related behaviors and memory. It was concluded that the orexinergic system is critically involved in reward-related behavior and significantly alters stress responses and stress-related psychiatric and mood disorders.

Sex-Related Predisposition to Post-Traumatic Stress Disorder Development-The Role of Neuropeptides

Post-traumatic stress disorder (PTSD) is characterized by re-experiencing a traumatic event, avoidance, negative alterations in cognitions and mood, hyperarousal, and severe functional impairment. Women have a two times higher risk of developing PTSD than men. The neurobiological basis for the sex-specific predisposition to PTSD might be related to differences in the functions of stress-responsive systems due to the interaction between gonadal hormones and stress peptides such as corticotropin-releasing factor (CRF), orexin, oxytocin, and neuropeptide Y. Additionally, in phases where estrogens levels are low, the risk of developing or exacerbating PTSD is higher. Most studies have revealed several essential sex differences in CRF function. They include genetic factors, e.g., the CRF promoter contains estrogen response elements. Importantly, sex-related differences are responsible for different predispositions to PTSD and diverse treatment responses. Fear extinction (the process responsible for the effectiveness of behavioral therapy for PTSD) in women during periods of high endogenous estradiol levels (the primary form of estrogens) is reportedly more effective than in periods of low endogenous estradiol. In this review, we present the roles of selected neuropeptides in the sex-related predisposition to PTSD development.

Subcutaneous Adipose Tissue Browning, Serum Orexin-A, and Insulin Resistance Following Aerobic Exercise in High-Fat Diet Obesity Male Wistar Rats

Background

Subcutaneous adipose tissue (SAT) relative to the other adipose tissues may have different roles in health and insulin resistance. The purpose of this study was to investigate the effectiveness of aerobic exercise on SAT thermogenesis indices, serum orexin-A (OXA), and insulin resistance in high-fat diet-induced obesity male Wistar rats.

Methods

Thirty-two male Wistar rats with an average weight of 180-200 g were randomly assigned into 4 equal groups: normal fat diet (NFD), high-fat diet obesity (HFDO), normal fat diet after high-fat diet obesity (HFDO-NFD), and aerobic exercise group with normal fat diet after high-fat diet obesity (HFDO-AEX). Fasting levels of serum OXA, insulin, FBS, high-density lipoproteins, low-density lipoproteins, cholesterol and gene expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and UCP1 in SAT were evaluated. Samples were taken in the HFDO group after obesity-induced and in other groups 48 h after 8 weeks of aerobic exercise.

Results

The results showed that HFD significantly decreased serum levels of OXA, HDL-c and gene expression of PGC1α and UCP1 in SAT. In addition, it caused a significant increase in Lee index, FBS, insulin resistance, and serum lipid profile in comparison with the NFD group (P ≤ 0.001). Aerobic exercise significantly modified the changes caused by HFD to the normal levels (P ≤ 0.001).

Conclusions

These data suggest that aerobic exercise caused an improvement in insulin resistance and blood lipid profiles through an increase in the serum level of OXA and alteration in the SAT phenotype from white to brown or beige.

Skin sympathetic nerve activity as a biomarker of fitness

BACKGROUND

Exercise stress testing is frequently used to expose cardiac arrhythmias. Aerobic exercise conditioning has been used as a nonpharmacologic antiarrhythmic intervention.

OBJECTIVE

The purpose of this study was to test the hypothesis that noninvasively recorded skin sympathetic nerve activity (SKNA) is increased during exercise and that SKNA response varies according to fitness levels.

METHODS

Oxygen consumption (VO2) and SKNA were recorded in 39 patients undergoing an incremental exercise test. Patients were grouped by 5 levels of fitness based on age, sex, and VO2max.

RESULTS

With exercise, all patients had a significant increase in average SKNA (aSKNA) (1.58 ± 1.12 μV to 4.50 ± 3.06 μV, P = .000) and heart rate (HR) (87.40 ± 20.42 bpm to 154.13 ± 16.82 bpm, P = .000). A mixed linear model of aSKNA was used with fixed effects of fitness, exercise time, and recovery time, and random effects of subject level intercept and slopes for exercise time and recovery times. The poor fitness group had significantly higher aSKNA than the other groups (P = .0273). For all subjects studied, aSKNA increased by 5% per minute with progression of exercise and decreased by 15% per minute with progression of recovery. The fitness variable encodes information on both comorbidities and body mass index (BMI). Once fitness level is known, comorbidities and BMI are not significantly associated with aSKNA. In all groups, aSKNA positively correlated with HR (R2 = 0.47 ± 0.23) and VO2 (R2 = 0.68 ± 0.25).

CONCLUSION

Fitness level determines the magnitude and time course of SKNA increase during exercise. SKNA may be a useful fitness biomarker in exercise stress testing.

(Neuro) Peptides, Physical Activity, and Cognition

Regular physical activity (PA) improves cognitive functions, prevents brain atrophy, and delays the onset of cognitive decline, dementia, and Alzheimer’s disease. Presently, there are no specific recommendations for PA producing positive effects on brain health and little is known on its mediators. PA affects production and release of several peptides secreted from peripheral and central tissues, targeting receptors located in the central nervous system (CNS). This review will provide a summary of the current knowledge on the association between PA and cognition with a focus on the role of (neuro)peptides. For the review we define peptides as molecules with less than 100 amino acids and exclude myokines. Tachykinins, somatostatin, and opioid peptides were excluded from this review since they were not affected by PA. There is evidence suggesting that PA increases peripheral insulin growth factor 1 (IGF-1) levels and elevated serum IGF-1 levels are associated with improved cognitive performance. It is therefore likely that IGF-1 plays a role in PA induced improvement of cognition. Other neuropeptides such as neuropeptide Y (NPY), ghrelin, galanin, and vasoactive intestinal peptide (VIP) could mediate the beneficial effects of PA on cognition, but the current literature regarding these (neuro)peptides is limited.

The contribution of orexins to sex differences in the stress response

Women are twice as likely as men to suffer from stress-related psychiatric disorders, such as post-traumatic stress disorder (PTSD) and Major Depressive Disorder (MDD), however, the biological basis of these sex differences is not fully understood. Interestingly, orexins are known to be dysregulated in these disorders. This review first discusses the important role of orexins regulating the response to stress. Next, we review the evidence for sex differences in the orexin system, in which the majority of both preclinical and clinical studies have reported higher orexin system expression in females. Finally, we discuss the functional consequences of these sex differences in orexin expression. Most importantly, the preclinical literature reveals that higher orexin system activity in females contributes to exaggerated neuroendocrine and behavioral responses to stress. In sum, the available data suggests that orexins may be important in the etiology of stress-related psychiatric disorders that present differently in men and women. Thus, targeting orexins could potentially ameliorate many phenotypes of stress-related illness in a sex-specific way.

Consequences on aging process and human wellness of generation of nitrogen and oxygen species during strenuous exercise

Impairment of antioxidant defense system and increase in metabolic rate and production of reactive oxygen species have been demonstrated in strenuous exercise. Both at rest and during contractile activity, skeletal muscle generates a very complex set of reactive nitrogen and oxygen species; the main generated are superoxide and nitric oxide. The nature of the contractile activity influences the pattern and the magnitude of this reactive oxygen and nitrogen species (ROS) generation. The intracellular pro-oxidant/antioxidant homeostasis undergoes alteration owing to strenuous exercise and the major identified sources of intracellular free radical generation during physical activity are the mitochondrial electron transport chain, polymorphoneutrophil, and xanthine oxidase. Reactive oxygen species increased tissue susceptibility to oxidative damage and pose a serious threat to the cellular antioxidant defense system. The possible dangerous consequences of the aging process and human wellness are emphasized in this review.

Aerobic Exercise and Metabolic Syndrome: The Role of Sympathetic Activity and the Redox System

BACKGROUND

Aerobic exercise can greatly assist in reducing collateral effects of metabolic syndrome (MetS). Moreover, aerobic exercise is associated with sympathetic activation and adaptive responses to sustain muscle engagement, changes in the release of Orexin A, a pleiotropic neuropeptide.

AIM

The aim of this study was to analyze the beneficial effects of aerobic exercise without dietary changes, in a cohort of MetS subjects, focusing on the role of sympathetic and orexinergic activity. Several blood parameters linked to MetS ROS production, heart rate, galvanic skin response, d-ROM test, and Orexin A serum levels were evaluated in ten males with MetS (BMI 30-34.9) before and after a period of 6 months of aerobic exercise compared to ten healthy subjects.

METHODS

Ten male subjects (aged 54 ± 4.16) with MetS (MetS group) and ten healthy males (aged 49.7 ± 2.79, Healthy group) were told about the study protocol and possible risks, signed the informed consent, and voluntarily participated in the study. Several blood parameters were evaluated in the two tested groups and were re-evaluated in the MetS group after 6 months of training (MetS6M group). The training protocol consisted of more than 30 min/day of walking (average speed of 4.5 km/h) and 3 days/week of aerobic activities (jogging under heart rate control - 120-140 bpm for 45 min).

RESULTS

The results showed that exercise induced a significant increase in GSR and plasma Orexin A but no significant increase in d-ROM values. Significant decreases in the serum ALT enzyme, triglycerides, and total cholesterol were found, while the HDL levels were significantly higher. Finally, a significant reduction of BMI and resting HR were reported.

CONCLUSION

The results of this study confirm that physical activity is associated with sympathetic activation, having a pivotal role against adverse effects linked to MetS. Moreover, this study demonstrates that, in patients with MetS, Orexin A is involved in hormonal adaptations to exercise.

Orexin-A Exerts Neuroprotective Effects via OX1R in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by progressive and selective death of dopaminergic neurons. Orexin-A is involved in many biological effects of the body. It has been reported that orexin-A has protective effects in cellular models of PD. However, little is known about the protective effects of orexin-A in animal parkinsonian models and the cellular mechanism has not yet been fully clarified. The aim of this study was to evaluate the effects of orexin-A in MPTP mice model of PD as well as the possible neuroprotective mechanisms of orexin-A on dopaminergic neurons. The results from animal experiments demonstrated that orexin-A attenuated the loss of dopaminergic neurons and the decrease of tyrosine hydroxylase (TH) expression in the substantia nigra, normalized the striatal dopaminergic fibers, and prevented the depletion of dopamine and its metabolites in the striatum. MPTP-treated mice showed cognitive impairments accompanied with significant motor deficiency. Orexin-A improved MPTP-induced impairments in both motor activity and spatial memory. Importantly, orexin-A increased the protein level of brain-derived neurotrophic factor (BDNF) in dopaminergic neurons of the substantia nigra. Furthermore, the protective effects of orexin-A on MPTP parkinsonian mice could be blocked by orexinergic receptor 1 (OX1R) antagonist, SB334867. In another set of experiments with SH-SY5Y dopaminergic cells, orexin-A significantly induced the expression of BDNF in a dose and time-dependent manner. The upregulation of BDNF is mainly concerned with PI3K and PKC signaling pathways via OX1R. The present study demonstrated that orexin-A exerted neuroprotective effects on MPTP parkinsonian mice, which may imply orexin-A as a potential therapeutic target for PD.

Orexin-A Exerts Neuroprotective Effects via OX1R in Parkinson's Disease

Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by progressive and selective death of dopaminergic neurons. Orexin-A is involved in many biological effects of the body. It has been reported that orexin-A has protective effects in cellular models of PD. However, little is known about the protective effects of orexin-A in animal parkinsonian models and the cellular mechanism has not yet been fully clarified. The aim of this study was to evaluate the effects of orexin-A in MPTP mice model of PD as well as the possible neuroprotective mechanisms of orexin-A on dopaminergic neurons. The results from animal experiments demonstrated that orexin-A attenuated the loss of dopaminergic neurons and the decrease of tyrosine hydroxylase (TH) expression in the substantia nigra, normalized the striatal dopaminergic fibers, and prevented the depletion of dopamine and its metabolites in the striatum. MPTP-treated mice showed cognitive impairments accompanied with significant motor deficiency. Orexin-A improved MPTP-induced impairments in both motor activity and spatial memory. Importantly, orexin-A increased the protein level of brain-derived neurotrophic factor (BDNF) in dopaminergic neurons of the substantia nigra. Furthermore, the protective effects of orexin-A on MPTP parkinsonian mice could be blocked by orexinergic receptor 1 (OX1R) antagonist, SB334867. In another set of experiments with SH-SY5Y dopaminergic cells, orexin-A significantly induced the expression of BDNF in a dose and time-dependent manner. The upregulation of BDNF is mainly concerned with PI3K and PKC signaling pathways via OX1R. The present study demonstrated that orexin-A exerted neuroprotective effects on MPTP parkinsonian mice, which may imply orexin-A as a potential therapeutic target for PD.

Orexins and stress

The neuropeptides orexins are important in regulating the neurobiological systems that respond to stressful stimuli. Furthermore, orexins are known to play a role many of the phenotypes associated with stress-related mental illness such as changes in cognition, sleep-wake states, and appetite. Interestingly, orexins are altered in stress-related psychiatric disorders such as Major Depressive Disorder and Anxiety Disorders. Thus, orexins may be a potential target for treatment of these disorders. In this review, we will focus on what is known about the role of orexins in acute and repeated stress, in stress-induced phenotypes relevant to psychiatric illness in preclinical models, and in stress-related psychiatric illness in humans. We will also briefly discuss how orexins may contribute to sex differences in the stress response and subsequent phenotypes relevant to mental health, as many stress-related psychiatric disorders are twice as prevalent in women.

Physical Activity, Immune System, and the Microbiome in Cardiovascular Disease

Cardiovascular health is a primary research focus, as it is a leading contributor to mortality and morbidity worldwide, and is prohibitively costly for healthcare. Atherosclerosis, the main driver of cardiovascular disease, is now recognized as an inflammatory disorder. Physical activity (PA) may have a more important role in cardiovascular health than previously expected. This review overviews the contribution of PA to cardiovascular health, the inflammatory role of atherosclerosis, and the emerging evidence of the microbiome as a regulator of inflammation.

The Effects of Moderate Physical Exercise on Adult Cognition: A Systematic Review

Background: Physical exercise is a systematic sequence of movements executed with a predefined purpose. This muscular activity impacts not only on circulatory adaptations, but also neuronal integration with the potential to influence cognition. The aim of this review was to determine whether the literature supports the idea that physical exercise promotes cognitive benefits in healthy adults.

Methods: A systematic search for relevant articles was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis criteria using available databases (PubMed, LILACS, Scopus, Web of Science, The Cochrane Library, OpenGrey, Google Scholar and CENTRAL). The search terms included “humans” or “adults” or “cognition” or “awareness” or “cognitive dissonance” or “cognitive reserve” or “comprehension” or “consciousness” and “motor activity” or “exercise” or “physical fitness,” and not “aged” or “nervous system diseases,” with the purpose of finding associations between moderate physical exercise and cognition. A methodological quality and risk of bias unit assessed the eligibility of articles.

Results: A total of 7179 articles were identified. Following review and quality assessment, three articles were identified to fulfill the inclusion criteria. An association between moderate physical exercise and cognition was observed. Improvements in cognitive parameters such as reduced simple reaction time, improved response precision and working memory were identified among the included articles.

Conclusion: This systematic review found that moderate physical exercise improves cognition.

Increased acetylcholine and glutamate efflux in the prefrontal cortex following intranasal orexin-A (hypocretin-1)

Orexin/hypocretin neurons of the lateral hypothalamus and perifornical area are integrators of physiological function. Previous work from our laboratory and others has shown the importance of orexin transmission in cognition. Age-related reductions in markers of orexin function further suggest that this neuropeptide may be a useful target for the treatment of age-related cognitive dysfunction. Intranasal administration of orexin-A (OxA) has shown promise as a therapeutic option for cognitive dysfunction. However, the neurochemical mechanisms of intranasal OxA administration are not fully understood. Here, we use immunohistochemistry and in vivo microdialysis to define the effects of acute intranasal OxA administration on: (i) activation of neuronal populations in the cortex, basal forebrain, and brainstem and (ii) acetylcholine (ACh) and glutamate efflux in the prefrontal cortex (PFC) of Fischer 344/Brown Norway F1 rats. Acute intranasal administration of OxA significantly increased c-Fos expression, a marker for neuronal activation, in the PFC and in subpopulations of basal forebrain cholinergic neurons. Subsequently, we investigated the effects of acute intranasal OxA on neurotransmitter efflux in the PFC and found that intranasal OxA significantly increased both ACh and glutamate efflux in this region. These findings were independent from any changes in c-Fos expression in orexin neurons, suggesting that these effects are not resultant from direct activation of orexin neurons. In total, these data indicate that intranasal OxA may enhance cognition through activation of distinct neuronal populations in the cortex and basal forebrain and through increased neurotransmission of ACh and glutamate in the PFC.

Sympathetic, Metabolic Adaptations, and Oxidative Stress in Autism Spectrum Disorders: How Far From Physiology?

Autism spectrum disorders (ASD) is a complex and multifaceted neurobehavioral syndrome with no specific cause still identified, despite the worldwide increasing (prevalence for 1,000 children from 6.7 to 14.6, between 2000 and 2012). Many biological and instrumental markers have been suggested as potential predictive factors for the precocious diagnosis during infancy and/or pediatric age. Many studies reported structural and functional abnormalities in the autonomic system in subjects with ASD. Sleep problems in ASD are a prominent feature, having an impact on the social interaction of the patient. Considering the role of orexins (A and B) in wake-sleep circadian rhythm, we could speculate that ASD subjects may present a dysregulation in orexinergic neurotransmission. Conversely, oxidative stress is implicated in the pathophysiology of many neurological disorders. Nonetheless, little is known about the linkage between oxidative stress and the occurrence or the progress of autism and autonomic functioning; some markers, such as heart rate (HR), heart rate variability (HRV), body temperature, and galvanic skin response (GSR), may be altered in the patient with this so complex disorder. In the present paper, we analyzed an autism case report, focusing on the rule of the sympathetic activity with the aim to suggest that it may be considered an important tool in ASD evaluation. The results of this case confirm our hypothesis even if further studies needed.

Functional Changes Induced by Orexin A and Adiponectin on the Sympathetic/Parasympathetic Balance

Obesity and lifestyle-related diseases are major problems faced by people in developed nations. Although exercise training prevents the progression of diabetes and obesity, the motivation for exercise is generally low in obese animals and humans. The autonomic nervous system (SNA) plays a crucial role in the regulation of eating behavior. Moreover, the SNA is involved in the body temperature regulation that is strictly related to body weight control, in accordance with the “thermoregulatory hypothesis” of food intake. Some neuronal peptides and hormones, like orexins and adiponectin, are also involved in the regulation of locomotion activity as well as food intake and metabolic rate. Furthermore, adiponectin as well as orexin A are involved in the control of body temperature, food intake and therefore in obesity-related diseases. The aim of this study was to investigate the changes in body temperature (Tc), and heart rate (HR) after an intracerebroventricular (ICV) injection of orexin A and adiponectin in animal model. The results of this study show that the orexin A levels are likely involved in the increase of Tc and HR. It is also clear that there is not a correlation between these parameters and adiponectin levels. Further studies are needed to assess adiponectin actions and outcome in the central nervous system in terms of energy expenditure, body temperature, heart rate and physical activity performance regulation.

Non-Rapid Eye Movement Sleep Parasomnias and Migraine: A Role of Orexinergic Projections

Introduction

Sleep and migraine share a common pathophysiological substrate, although the underlying mechanisms are unknown. The serotonergic and orexinergic systems are both involved in the regulation of sleep/wake cycle, and numerous studies show that both are involved in the migraine etiopathogenesis. These two systems are anatomically and functionally interconnected. Our hypothesis is that in migraine a dysfunction of orexinergic projections on the median raphe (MR) nuclei, interfering with serotonergic regulation, may cause Non-Rapid Eye Movement parasomnias, such as somnambulism.

Hypothesis/theory

Acting on the serotonergic neurons of the raphe nuclei, the dysfunction of orexinergic neurons would lead to a higher release of serotonin. The activation of serotonergic receptors located on the walls of large cerebral vessels would lead to abnormal vasodilatation and consequently increase transmural pressure. This process could activate the trigeminal nerve terminals that innervate vascular walls. As a consequence, there is activation of sensory nerve endings at the level of hard vessels in the meninges, with release of pro-inflammatory peptides (e.g., substance P and CGRP). Within this hypothetical frame, the released serotonin could also interact with trigeminovascular afferents to activate and/or facilitate the release of the neuropeptide at the level of the trigeminal ganglion. The dysregulation of the physiological negative feedback of serotonin on the orexinergic neurons, in turn, would contribute to an alteration of the whole system, altering the sleep–wake cycle.

Conclusion

Serotonergic neurons of the MR nuclei receive an excitatory input from hypothalamic orexin/hypocretin neurons and reciprocally inhibit orexin/hypocretin neurons through the serotonin 1A receptor (or 5-HT1A receptor). Considering this complex system, if there is an alteration it may facilitate the pathophysiological mechanisms involved in the migraine, while it may produce at the same time an alteration of the sleep–wake rhythm, causing sleep disorders such as sleepwalking. Understanding the complex mechanisms underlying migraine and sleep disorders and how these mechanisms can interact with each other, it would be crucial to pave the way for new therapeutic strategies.

Influence of Football on Physiological Cardiac Indexes in Professional and Young Athletes

Background: After long-term intensive training, considerable morphological and functional heart changes occur in professional athletes. Such changes arise progressively and regress upon interruption of the physical activity. Morphological and functional alterations on heart are known as “Athlete's heart” condition.

Objective: This study aims to compare echocardiographic parameters in two different groups of professional athletes. Furthermore, a prospective study is performed analyzing the echocardiographic changes occurring in 12 professional players in 3 years of follow-up.

Materials and Methods: 78 football players were examined from July 2011 to May 2016 (40 enrolled in Group A and 38 in Group B). Twelve players of GROUP A were followed for 3 consecutive seasons. The general clinical examination, the cardiopulmonary evaluation, the ECG, the ergometer stress test, the spirometric examination and the standard cardiac eco color doppler test were recorded.

Results: Left ventricle dimensions, left atrium dimensions, and interventricular septum dimensions were higher in A players than in B players. Moreover, following up 12 players for 3 years, a statistically significant increase of such values was observed.

Discussion: In A players, higher dimensions of the left chambers and the interventricular septum were observed, compared to B players. No statistically significant difference was found regarding the ejection fraction. The 3 years follow-up showed a statistically significant increase of both left chambers and interventricular septum dimensions, particularly in the second and third year.

Conclusions: These findings demonstrated that A players have higher echocardiographic parameters respect to B players. The results of this study support the scientific theory that long-term intensive training influences heart function, inducing “athlete's heart” with morphological adaptations. No significant echocardiographic variation within the examined sample was observed for different roles (goalkeeper, defender, midfielder, or attacker) or skills of individual players.

Functional Changes of Orexinergic Reaction to Psychoactive Substances

It is becoming increasingly apparent the importance of the central nervous system (CNS) as the major contributor to the regulation of systemic metabolism. Antipsychotic drugs are used often to treat several psychiatric disorders, including schizophrenia and bipolar disorder However, antipsychotic drugs prescription, particularly the second-generation ones (SGAs), such as clozapine and olanzapine, is related to a considerable weight gain which usually leads to obesity. The aim of this paper is to assess the influence of orexin A on sympathetic and hyperthermic reactions to several neuroleptic drugs. Orexin A is a neuropeptide which effects both body temperature and food intake by increasing sympathetic activity. Orexin A-mediated hyperthermia is reduced by haloperidol and is blocked by clozapine and olanzapine. Orexin A-mediated body temperature elevation is increased by risperidone. These hyperthermic effects are delayed by quietapine. In this paper, it is discussed the orexinergic pathway activation by neuroleptic drugs and its influence on human therapeutic strategies. With the aim to determine that neuroleptic drugs mediate body temperature control through to the orexinergic system, we summarized our previously published data. Psychiatric disorders increase the risk of developing metabolic disorders (e.g., weight gain, increased blood pressure, and glucose or lipid levels). Therefore, the choice of antipsychotic drug to be prescribed, based on the relevant risks and benefits of each individual drug, has an essential role in human health prevention.

Role of Sex Hormones in the Control of Vegetative and Metabolic Functions of Middle-Aged Women

Aims: In women's life, menopause is characterized by significant physiological changes often associated with an increase in body mass and obesity-associated sicknesses. Numerous researches described interdependencies of estrogen deficiency, aging, and resting energy expenditure (REE) downfall in the obesity correlated with the menopause. The aim of this study was to determining whether healthy, obese menopausal women underwent HRT treatment, showed changes in their REE, autonomic asset, and assessment of oxidative stress in comparison with obese pre- and post-menopausal women.

Methodology: In this study, we measured the body composition, the REE, the oxidative stress, the diet assimilation, and the autonomic nervous system activity in three groups: pre-menopause women (n = 50), post-menopause women following hormone-replacement therapy (HRT; n = 50), and post-menopause women not following HRT (n = 50).

Results: In the group with HRT a significant increase of the sympathetic activity and REE was described. Finally this group showed a notable increment of oxidative stress compared with the others, and utilizing BIA instrument, the free fat mass was increased respect to the fat mass of obese women.

Conclusion: The study highlights the importance of the HRT-related physiological changes that influence body weight in menopause women. This results are important because have a practical implications for prevention and/or treatment of the obesity.

Neuropeptide S increases motor activity and thermogenesis in the rat through sympathetic activation

The central role of neuropeptide S (NPS), identified as the endogenous ligand for GPR154, now named neuropeptide S receptor (NPSR), has not yet been fully clarified. We examined the central role of NPS for body temperature, energy expenditure, locomotor activity and adrenal hormone secretion in rats. Intracerebroventricular (icv) injection of NPS increased body temperature in a dose-dependent manner. Energy consumption and locomotor activity were also significantly increased by icv injection of NPS. In addition, icv injection of NPS increased the peripheral blood concentration of adrenalin and corticosterone. Pretreatment with the β1- and β2-adrenergic receptor blocker timolol inhibited the NPS-induced increase of body temperature. The expression of both NPS mRNA in the brainstem and NPSR mRNA in the hypothalamus showed a nocturnal rhythm with a peak occurring during the first half of the dark period. To examine whether the endogenous NPS is involved in regulation of body temperature, NPSR antagonist SHA68 was administered one hour after darkness. SHA68 attenuated the nocturnal rise of body temperature. These results suggest that NPS contributes to the regulation of the sympathetic nervous system.

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.

Orexin System: The Key for a Healthy Life

The orexin-A/hypocretin-1 and orexin-B/hypocretin-2 are neuropeptides synthesized by a cluster of neurons in the lateral hypothalamus and perifornical area. Orexin neurons receive a variety of signals related to environmental, physiological and emotional stimuli, and project broadly to the entire CNS. Orexin neurons are “multi-tasking” neurons regulating a set of vital body functions, including sleep/wake states, feeding behavior, energy homeostasis, reward systems, cognition and mood. Furthermore, a dysfunction of orexinergic system may underlie different pathological conditions. A selective loss orexin neurons was found in narcolepsia, supporting the crucial role of orexins in maintaining wakefulness. In animal models, orexin deficiency lead to obesity even if the consume of calories is lower than wildtype counterpart. Reduced physical activity appears the main cause of weight gain in these models resulting in energy imbalance. Orexin signaling promotes obesity resistance via enhanced spontaneous physical activity and energy expenditure regulation and the deficiency/dysfunction in orexins system lead to obesity in animal models despite of lower calories intake than wildtype associated with reduced physical activity. Interestingly, orexinergic neurons show connections to regions involved in cognition and mood regulation, including hippocampus. Orexins enhance hippocampal neurogenesis and improve spatial learning and memory abilities, and mood. Conversely, orexin deficiency results in learning and memory deficits, and depression.

Neuroprotective Effects of Physical Activity: Evidence from Human and Animal Studies

In the present article, we provide a review of current knowledge regarding the role played by physical activity (PA) in preventing age-related cognitive decline and reducing risk of dementia. The cognitive benefits of PA are highlighted by epidemiological, neuroimaging and behavioral studies. Epidemiological studies identified PA as an influential lifestyle factor in predicting rates of cognitive decline. Individuals physically active from midlife show a reduced later risk of cognitive impairment. Neuroimaging studies documented attenuation of age-related brain atrophy, and also increase of gray matter and white matter of brain areas, including frontal and temporal lobes. These structural changes are often associated with improved cognitive performance. Importantly, the brain regions that benefit from PA are also those regions that are often reported to be severely affected in dementia. Animal model studies provided significant information about biomechanisms that support exercise-enhanced neuroplasticity, such as angiogenesis and upregulation of growth factors. Among the growth factors, the brain-derived neurotrophic factor seems to play a significant role. Another putative factor that might contribute to beneficial effects of exercise is the neuropeptide orexin-A. The beneficial effects of PA may represent an important resource to hinder the cognitive decline associated with aging.

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.

Exercise Influence on Hippocampal Function: Possible Involvement of Orexin-A

In the present article, we provide a brief review of current knowledge regarding the effects induced by physical exercise on hippocampus. Research involving animals and humans supports the view that physical exercise, enhancing hippocampal neurogenesis and function, improves cognition, and regulates mood. These beneficial effects depend on the contribute of more factors including the enhancement of vascularization and upregulation of growth factors. Among these, the BDNF seems to play a significant role. Another putative factor that might contribute to beneficial effects of exercise is the orexin-A. In support of this hypothesis there are the following observations: (1) orexin-A enhances hippocampal neurogenesis and function and (2) the levels of orexin-A increase with physical exercise. The beneficial effects of exercise may represent an important resource to hinder the cognitive decline associated with the aging-related hippocampal deterioration and ameliorate depressive symptoms.

Obesity and brain illness: from cognitive and psychological evidences to obesity paradox

Recent findings showed that obesity represents an additional risk factor to developing brain illness such as cognitive impairments and psychopathological disorders. However, some benefits of overweight in the elderly have been identified and an "obesity paradox" has been shown. Currently, it is still unknown how obesity and brain functioning could be linked, and the process by which body fat independently injures cognitive abilities and psychological well-being remains unclear. To establish the independent role of obesity on cognitive abilities and mental health, clarifying the role played by several factors and understanding their interaction is essential. In this review, we discuss the relationship between obesity and brain illness and underline the role played by confounders and other covariates to determine this link.

Quality of life in overweight (obese) and normal-weight women with polycystic ovary syndrome

OBJECTIVE

Polycystic ovary syndrome (PCOS) is characterized by phenotypic heterogeneity and has a wide variety of consequences. Approximately half of women with PCOS are overweight or obese, and their obesity may be a contributing factor to PCOS pathogenesis through different mechanisms. The aim of this study was to evaluate if PCOS alone affects the patients' quality of life and to what extent obesity contributes to worsen this disease.

DESIGN

To evaluate the impact of PCOS on health-related quality-of-life (HRQoL), 100 Mediterranean women with PCOS (group A), 50 with a body mass index (BMI) >25 kg/m² (group A₁) and 50 with BMI <25 kg/m² (group A₂), were recruited. They were evaluated with a specific combination of standardized psychometric questionnaires: the Symptom Checklist-90 Revised, the 36-Item Short-Form Health Survey, and the Polycystic Ovary Syndrome Questionnaire. The patients were compared with a normal-weight healthy control group of 40 subjects (group B). Another control group of 40 obese healthy women (group C) was used to make a comparison with PCOS obese patients (A₁).

RESULTS

Our results showed a considerable worsening of HRQoL in PCOS patients (A) compared with controls (B). In addition, patients with PCOS and BMI >25 (A₁) showed a significant and more marked reduction in scores, suggesting a lower quality of life, compared with controls (B) and with normal-weight PCOS patients (A₂).

CONCLUSION

PCOS is a complex disease that alone determines a deterioration of HRQoL. The innovative use of these psychometric questionnaires in this study, in particular the PCOS questionnaire, has highlighted that obesity has a negative effect on HRQoL. It follows that a weight decrease is associated to phenotypic spectrum improvement and relative decrement in psychological distress.