Exercise offers anxiolytic potential: a role for stress and brain noradrenergic-galaninergic mechanisms

Acute Exercise Improves Large-Scale Brain Network Segregation in Healthy Older Adults

Introduction: Age-related cognitive decline and mental health problems are accompanied by changes in resting-state functional connectivity (rsFC) indices, such as reduced brain network segregation. Meanwhile, exercise can improve cognition, mood, and neural network function in older adults. Studies on effects of exercise on rsFC outcomes in older adults have chiefly focused on changes after exercise training and suggest improved network segregation through enhanced within-network connectivity. However, effects of acute exercise on rsFC measures of neural network integrity in older adults, which presumably underlie changes observed after exercise training, have received less attention. In this study, we hypothesized that acute exercise in older adults would improve functional segregation of major cognition and affect-related brain networks. Methods: To test this, we analyzed rsFC data from 37 healthy and physically active older adults after they completed 30 min of moderate-to-vigorous intensity cycling and after they completed a seated rest control condition. Conditions were performed in a counterbalanced order across separate days in a within-subject crossover design. We considered large-scale brain networks associated with cognition and affect, including the frontoparietal network (FPN), salience network (SAL), default mode network (DMN), and affect-reward network (ARN). Results: We observed that after acute exercise, there was greater segregation between SAL and DMN, as well as greater segregation between SAL and ARN. Conclusion: These findings indicate that acute exercise in active older adults alters rsFC measures in key cognition and affect-related networks in a manner that opposes age-related dedifferentiation of neural networks that may be detrimental to cognition and mental health.

Exercise as Treatment for "Stress-Related" Mental Disorders

The beneficial impact of physical activity on preventing and treating mental disorders has captured growing (research) interest. This article aims to provide a concise overview of essential evidence regarding the effectiveness and underlying mechanisms of physical activity for individuals with mental disorders clustered as "stress-related" conditions. Empirical findings (e.g., longitudinalprospective studies, interventional randomized-controlled-trials, reviews, meta-analyses) regarding the effects of physical activity in the prevention and treatment of stress-related mental disorders are summarized. Furthermore, potential mechanisms underlying these effects are discussed, and recommendations regarding the use of physical activity are outlined. The majority of studies indicate good efficacy of physical activity in prospectively lowering the risk for the incidence of subsequent stress-related mental disorders as well as in the treatment of manifest disorders. Most evidence targets unipolar depressive disorder and, secondly, anxiety disorders. Research regarding posttraumatic stress disorder, obsessive-compulsive disorders, and somatoform disorders is promising but scarce. Physical activity seems to be useful as a stand-alone-treatment as well as in combination with other psychotherapeutic or pharmacological treatments. Multiple intertwined physiological, psychological, and social mechanisms are assumed to mediate the beneficial effects. Recommendations regarding physical activity can orientate on official guidelines but should consider the individual needs and circumstances of each subject. In summary, physical activity seems to be effective in the prevention and treatment of stressrelated mental disorders and, therefore, should be fostered in healthcare-settings. Future studies are needed to clarify partly inconsistent patterns of results and to close research gaps, e.g., concerning somatoform disorders.

Emotional processing and positive affect after acute exercise in healthy older adults

The well-elucidated improvement of mood immediately after exercise in older adults presumably involves adaptations in emotion-processing brain networks. However, little is known about effects of acute exercise on appetitive and aversive emotion-related network recruitment in older adults. The purpose of this study was to determine the effect of acute exercise, compared to a seated rest control condition, on pleasant and unpleasant emotion-related regional activation in healthy older adults. Functional MRI data were acquired from 32 active older adults during blocked presentations of pleasant, neutral and unpleasant images from the International Affective Pictures System. fMRI data were collected after participants completed 30 min of moderate to vigorous intensity cycling or seated rest, performed in a counterbalanced order across separate days in a within-subject design. The findings suggest three ways that emotional processing in the brain may be different immediately after exercise (relative to immediately after rest): First, reduced demands on emotional regulation during pleasant emotional processing as indicated by lower precuneus activation for pleasant stimuli; second, reduced processing of negative emotional stimuli in visual association areas as indicated by lower activation for unpleasant stimuli in the bilateral fusiform and ITG; third, an increased recruitment in activation associated with regulating/inhibiting unpleasant emotional processing in the bilateral medial superior frontal gyrus (dorsomedial prefrontal cortex), angular gyri, supramarginal gyri, left cerebellar crus I/II and a portion of right dorsolateral prefrontal cortex. Overall, these findings support that acute exercise in active older adults alters activation in key emotional processing and regulating brain regions.

A Study of Brain Function Characteristics of Service Members at High Risk for Accidents in the Military

Military accidents are often associated with stress and depressive psychological conditions among soldiers, and they often fail to adapt to military life. Therefore, this study analyzes whether there are differences in EEG and pulse wave indices between general soldiers and three groups of soldiers who have not adapted to military life and are at risk of accidents. Data collection was carried out using a questionnaire and a device that can measure EEG and pulse waves, and data analysis was performed using SPSS. The results showed that the concentration level and brain activity indices were higher in the general soldiers and the soldiers in the first stage of accident risk. The body stress index was higher for each stage of accident risk, and the physical vitality index was higher for general soldiers. Therefore, it can be seen that soldiers who have not adapted to military life and are at risk of accidents have somewhat lower concentration and brain activity than general soldiers, and have symptoms of stress and lethargy. The results of this study will contribute to reducing human accidents through EEG and pulse wave measurements not only in the military but also in occupations with a high risk of accidents such as construction.

Dramatic impacts on brain pathology, anxiety, and cognitive function in the knock-in APPNL-G-F mouse model of Alzheimer disease following long-term voluntary exercise

Background

An active lifestyle is associated with improved cognitive functions in aged people and may prevent or slow down the progression of various neurodegenerative diseases including Alzheimer’s disease (AD). To investigate these protective effects, male APP^NL-G-F mice were exposed to long-term voluntary exercise.

Methods

Three-month-old AD mice were housed in a cage supplemented with a running wheel for 9 months for long-term exercise. At the age of 12 months, behavioral tests were completed for all groups. After completing behavioral testing, their brains were assessed for amyloid pathology, microgliosis, and cholinergic cells.

Results

The results showed that APP^NL-G-F mice allowed to voluntarily exercise showed an improvement in cognitive functions. Furthermore, long-term exercise also improved anxiety in APP^NL-G-F mice as assessed by measuring thigmotaxis in the Morris water task. We also found reductions in amyloid load and microgliosis, and a preservation of cholinergic cells in the brain of APP^NL-G-F mice allowed to exercise in their home cages. These profound reductions in brain pathology associated with AD are likely responsible for the observed improvement of learning and memory functions following extensive and regular exercise.

Conclusion

These findings suggest the potential of physical exercise to mitigate the cognitive deficits in AD.

Effects of treadmill exercise on anxiety-like behavior in association with changes in estrogen receptors ERα, ERβ and oxytocin of C57BL/6J female mice

Exercise can reduce the incidence of stress-related mental diseases, such as depression and anxiety. Control group was neither exposed to CVMS nor TRE (noCVMS/noTRE). Females were tested and levels of serum17-beta-oestradiol (E₂), estrogen receptors α immunoreactive neurons (ERα-IRs), estrogen receptors β immunoreactive neurons (ERβ-IRs) and oxytocin immunoreactive neurons (OT-IRs) were measured. The results showed there's increased anxiety-like behaviors for mice from CVMS/noTRE, CVMS/higher speed TRE (CVMS/HTRE) and noCVMS/HTRE groups when they were put in open field and elevated maze tests. They had lower serum E₂ levels than mice from CVMS/low-moderate speed TRE (CVMS/LMTRE), noCVMS/LMTRE and noCVMS/noTRE groups. The three groups of CVMS/noTRE, CVMS/HTRE and noCVMS/HTRE mice had more ERα-IRs and less ERβ-IRs in the medial preoptic area (mPOA), bed nucleus of the stria terminalis (BNST) and medial amygdala (MeA), hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). The number of OT-IRs in PVN and SON of CVMS/noTRE, CVMS/HTRE and noCVMS/HTRE mice was also lower than that of mice from CVMS/LMTRE, noCVMS/LMTRE and noCVMS/noTRE groups. Interestingly, CVMS/LMTRE and noCVMS/LMTRE mice were similar to noCVMS/noTRE mice in that they did not show anxiety, while CVMS/HTRE and noCVMS/HTRE mice did not, which were similar to the mice in CVMS/noTRE. We propose that LMTRE instead of HTRE changes the serum concentration of E₂. ERβ/ERα ratio and OT level in the brain may be responsible for the decrease in anxiety-like behavior in female mice exposed to anxiety-inducing stress conditions.

Co-released norepinephrine and galanin act on different timescales to promote stress-induced anxiety-like behavior

Both the noradrenergic and galaninergic systems have been implicated in stress-related neuropsychiatric disorders, and these two neuromodulators are co-released from the stress-responsive locus coeruleus (LC); however, the individual contributions of LC-derived norepinephrine (NE) and galanin to behavioral stress responses are unclear. Here we aimed to disentangle the functional roles of co-released NE and galanin in stress-induced behavior. We used foot shock, optogenetics, and behavioral pharmacology in wild-type (WT) mice and mice lacking either NE (Dbh^-/-) or galanin (Gal^cKO-Dbh) specifically in noradrenergic neurons to isolate the roles of these co-transmitters in regulating anxiety-like behavior in the elevated zero maze (EZM) either immediately or 24 h following stress. Foot shock and optogenetic LC stimulation produced immediate anxiety-like behavior in WT mice, and the effects of foot shock persisted for 24 h. NE-deficient mice were resistant to the anxiogenic effects of acute stress and optogenetic LC stimulation, while mice lacking noradrenergic-derived galanin displayed typical increases in anxiety-like behavior. However, when tested 24 h after foot shock, both Dbh^-/- and Gal^cKO-Dbh mice lacked normal expression of anxiety-like behavior. Pharmacological rescue of NE, but not galanin, in knockout mice during EZM testing was anxiogenic. In contrast, restoring galanin, but not NE, signaling during foot shock normalized stress-induced anxiety-like behavior 24 h later. These results indicate that NE and noradrenergic-derived galanin play complementary, but distinguishable roles in behavioral responses to stress. NE is required for the expression of acute stress-induced anxiety, while noradrenergic-derived galanin mediates the development of more persistent responses following a stressor.

Protective effects of forced exercise against topiramate-induced cognition impairment and enhancement of its antiepileptic activity: molecular and behavioral evidences

Propose/aim of study: Forced exercise can act as a neuroprotective factor and cognitive enhancer. The aim of the current study was to evaluate the effects of forced exercise on topiramate (TPM) induced cognitive impairment and also on TPM anti-seizure activity and neurodegeneration status after seizure.Material and method: Forty adult male rats were divided into four groups receiving normal saline, TPM (100 mg/kg), TPM in combination with forced exercise and forced exercise only respectively for 21 days. MWM test, and PTZ induced seizure were used and some oxidative, inflammatory and apoptotic biomarkers were measured for assessment of experimental animals.Results: Forced exercise in combination with TPM could abolish the TPM induced cognitive impairment and potentiates its anti-seizure activity. Also forced exercise in combination with TPM decreased malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) and Bax protein, while caused increase in superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities after PTZ administration.Conclusion: It seems that forced exercise could act as an adjunct therapy with TPM for management of induced cognitive impairment and can also potentiate TPM antiepileptic and neuroprotective effects.

Inhibition of mTOR signaling by genetic removal of p70 S6 kinase 1 increases anxiety-like behavior in mice

The mechanistic target of rapamycin (mTOR) is a ubiquitously expressed kinase that acts through two complexes, mTORC1 and mTORC2, to regulate protein homeostasis, as well as long lasting forms of synaptic and behavioral plasticity. Alteration of the mTOR pathway is classically involved in neurodegenerative disorders, and it has been linked to dysregulation of cognitive functions and affective states. However, information concerning the specific involvement of the p70 S6 kinase 1 (S6K1), a downstream target of the mTORC1 pathway, in learning and memory processes and in the regulation of affective states remains scant. To fill this gap, we exposed adult male mice lacking S6K1 to a battery of behavioral tests aimed at measuring their learning and memory capabilities by evaluating reference memory and flexibility with the Morris water maze, and associative memory using the contextual fear conditioning task. We also studied their anxiety-like and depression-like behaviors by, respectively, performing elevated plus maze, open field, light-dark emergence tests, and sucrose preference and forced swim tests. We found that deleting S6K1 leads to a robust anxious phenotype concomitant with associative learning deficits; these symptoms are associated with a reduction of adult neurogenesis and neuronal atrophy in the hippocampus. Collectively, these results provide grounds for the understanding of anxiety reports after treatments with mTOR inhibitors and will be critical for developing novel compounds targeting anxiety.

Rat models for low and high adaptive response to exercise differ for stress-related memory and anxiety

Physical exercise and fitness may serve as resilience factors to stress exposure. However, the extreme range in human exercise performance suggests that genetic variation for exercise capacity could be a confounding feature to understanding the connection between exercise and stress exposure. To test this idea, we use laboratory rat models selectively bred for a low and high gain in aerobic running capacity in response to training to examine whether an inherent capacity to respond to physical exercise reflects how stress changes neurobiological functioning and regulates fear-associated memory processing. Utilization of this contrasting rat model system of low and high responders has the potential to guide the interpretation of the reported association with exercise involvement and the reduction of stress-induced anxiety disorders. Our data show that aerobic fitness may be linked to the ability to regulate fear-associated memories. We also show that acquired exercise capacity may play a key role in regulating responses to an acute stressor. Exercise sensitivity plays a significant role in the activation of the plasticity-associated molecule extracellular signal-regulated kinase, changes in stress hormone activity, and anatomical modifications to the noradrenergic locus coeruleus. These data identify a unique operational mechanism that may serve as translational targets for lessening symptoms of stress and anxiety.

Physical Activity and Natural Products and Minerals in the SARS-CoV-2 Pandemic: An Update

Coronavirus-disease 19 (COVID-19) has rapidly become a global public health issue, and there is a desperate need for strategies of prevention, reduction, and treatment to halt the epidemic. The coronavirus affects the immune system, and individuals with a compromised immune system, such as those with diabetes, hypertension, obesity, are more susceptible to this virus. Lifestyle-related variables such as physical activity and nutritional supplements can decrease inflammatory markers, increase anti-inflammatory and antioxidant status, and improve the immune system. Lifesty-lerelated variables play preventive roles against various infectious diseases including COVID-19. This review highlights the effects of physical activity and nutrients supplements on the immune system and their possible benefits in combating the harms caused by infection with the COVID-19 virus.

Impact of exercise on older adults' mood is moderated by sleep and mediated by altered brain connectivity

Older adults comprise the fastest growing global demographic and are at increased risk of poor mental health outcomes. Although aerobic exercise and sleep are critical to the preservation of emotional well-being, few studies have examined their combined mood-enhancing effects, or the potential neural mechanisms underlying these effects. Here, we used a randomized crossover design to test the impact of acute exercise on mood and the intrinsic functional connectivity (iFC) of the cingulo-opercular network in physically healthy older adults. Wrist actigraphy provided objective indices of sleep. Results revealed that 30 min of moderate-intensity aerobic exercise acutely enhanced positive affect (PA) and reduced iFC between the cingulo-opercular network and the hippocampus. Both effects were magnified among older adults with greater sleep disturbance. Exercise-induced changes in hippocampal iFC mediated relations between sleep disturbance and exercise-induced increases in PA. These findings provide evidence that aerobic exercise enhances mood, that it does so by altering connectivity between the anterior insula-a key hub in the cingulo-opercular network-and the hippocampus and that lower sleep quality is a stronger predictor of these effects among older adults. These observations underscore the benefits of moderate-intensity exercise-a safe and scalable behavioral intervention-and provide new clues about the neural circuitry underlying the interactive effects of sleep and exercise on mood.

Effects of adolescent experience of food restriction and exercise on spatial learning and open field exploration of female rats

The hippocampus carries out multiple functions: spatial cognition dorsally (DH) and regulation of emotionality-driven behavior ventrally (VH). Previously, we showed that dendrites of DH and VH pyramidal neurons of female rats are still developing robustly during adolescence and are altered by the experience of food restriction and voluntary exercise on a wheel. We tested whether such anatomical changes during adolescence impact anxiety-like behavior and spatial cognition. Four groups of female rats were evaluated for these behaviors: those with wheel access in its cage from postnatal day (P) 36-44 (EX); those with food access restricted to 1 hr per day, from P40 to 44 (FR); those with EX from P36 to 44, combined with FR from P40 to 44, which we will refer to as EX + FR; and controls, CON (no EX, no FR). Open field test for anxiety-like behavior and active place avoidance test for spatial cognition were conducted at P47-49, the age when food restricted animals have restored body weight, or at P54-56, to identify more enduring effects. Anxiety-like behavior was elevated for the EX and FR groups at P47-49 but not for the EX + FR group. By P54-56, the EX + FR and EX groups exhibited less anxiety-like behavior, indicating a beneficial delayed main effect of exercise. There was a beneficial main effect of food restriction upon cognition, as the FR group showed cognition superior to CONs' at P44-46 and P54-56, while the EX + FR animals also showed enhanced spatial learning at P54-56. EX + FR animals with best adaptation to the feeding schedule showed the best spatial learning performance but with a delay. The EX group exhibited only a transient improvement. These findings indicate that FR, EX, and EX + FR in mid-adolescence are all beneficial in reducing anxiety-like behavior and improving spatial cognition but with subtle differences in the timing of their manifestation, possibly reflecting the protracted maturation of the hippocampus.

Effect of Acute Aerobic Exercise on Ocular Measures of Attention to Emotionally Expressive Faces

BACKGROUND

Mechanisms underlying exercise-induced mood enhancement are not well understood, but it is plausible that adaptive changes in attention to emotional stimuli underlie this effect. Thus, this study examined the effects of acute aerobic exercise on eye-tracking metrics while participants viewed emotionally expressive faces.

METHODS

Thirty-four adults (18 women) aged 21.1 ± 1.4 years completed two counterbalanced 30-min conditions: vigorous running or seated rest. Eye tracking occurred pre- and 20-min post-condition. Participants viewed positive (n = 15), negative (n = 15), and neutral (n = 15) emotional facial expressions from the NimStim repository. Fixation duration, longest fixation, number of fixations, and scan path length were analyzed using repeated measures ANOVAs.

RESULTS

Exercise improved mood, but had no effect on the dependent measures (all 3-way interactions p > 0.66). However, a main effect of emotionally expressive content for fixation duration (p = 0.04, η = 0.10) and a marginally significant effect for longest fixation (p = 0.06, ηp2 = 0.09) were detected, such that fixation duration and longest fixation were greatest for faces expressing positive emotions.

CONCLUSION

These preliminary findings indicated that acute exercise did not alter the processing of expressive faces as indexed by eye-tracking metrics of attention. However, eye tracking effectively detected processing patterns indicative of a pleasure bias while viewing emotional facial expressions.

Possible Neuroprotective Mechanisms of Physical Exercise in Neurodegeneration

Physical exercise (PE) improves physical performance, mental status, general health, and well-being. It does so by affecting many mechanisms at the cellular and molecular level. PE is beneficial for people suffering from neuro-degenerative diseases because it improves the production of neurotrophic factors, neurotransmitters, and hormones. PE promotes neuronal survival and neuroplasticity and also optimizes neuroendocrine and physiological responses to psychosocial and physical stress. PE sensitizes the parasympathetic nervous system (PNS), Autonomic Nervous System (ANS) and central nervous system (CNS) by promoting many processes such as synaptic plasticity, neurogenesis, angiogenesis, and autophagy. Overall, it carries out many protective and preventive activities such as improvements in memory, cognition, sleep and mood; growth of new blood vessels in nervous system; and the reduction of stress, anxiety, neuro-inflammation, and insulin resistance. In the present work, the protective effects of PE were overviewed. Suitable examples from the current research work in this context are also given in the article.

The role of the locus coeruleus in the generation of pathological anxiety

This review aims to synthesise a large pre-clinical and clinical literature related to a hypothesised role of the locus coeruleus norepinephrine system in responses to acute and chronic threat, as well as the emergence of pathological anxiety. The locus coeruleus has widespread norepinephrine projections throughout the central nervous system, which act to globally modulate arousal states and adaptive behavior, crucially positioned to play a significant role in modulating both ascending visceral and descending cortical neurocognitive information. In response to threat or a stressor, the locus coeruleus–norepinephrine system globally modulates arousal, alerting and orienting functions and can have a powerful effect on the regulation of multiple memory systems. Chronic stress leads to amplification of locus coeruleus reactivity to subsequent stressors, which is coupled with the emergence of pathological anxiety-like behaviors in rodents. While direct in vivo evidence for locus coeruleus dysfunction in humans with pathological anxiety remains limited, recent advances in high-resolution 7-T magnetic resonance imaging and computational modeling approaches are starting to provide new insights into locus coeruleus characteristics.

Sex differences in resilience: Experiential factors and their mechanisms

Adverse life events can lead to stable changes in brain structure and function and are considered primary sources of risk for post-traumatic stress disorder, depression and other neuropsychiatric disorders. However, most individuals do not develop these conditions following exposure to traumatic experiences, and research efforts have identified a number of experiential factors associated with an individual's ability to withstand, adapt to and facilitate recovery from adversity. While multiple animal models of stress resilience exist, so that the detailed biological mechanisms can be explored, studies have been disproportionately conducted in male subjects even though the prevalence and presentation of stress-linked disorders differ between sexes. This review focuses on (a) the mechanisms by which experiential factors (behavioral control over a stressor, exercise) reduce the impact of adverse events as studied in males; (b) whether other manipulations (ketamine) that buffer against stress-induced sequelae engage the same circuit features; and (c) whether these processes operate similarly in females. We argue that investigation of experiential factors that produce resistance/resilience rather than vulnerability to adversity will generate a unique set of biological mechanisms that potentially underlie sex differences in mood disorders.

Acute aerobic exercise enhances pleasant compared to unpleasant visual scene processing

Although acute aerobic exercise benefits different aspects of emotional functioning, it is unclear how exercise influences the processing of emotional stimuli and which brain mechanisms support this relationship. We assessed the influence of acute aerobic exercise on valence biases (preferential processing of negative/positive pictures) by performing source reconstructions of participants' brain activity after they viewed emotional scenes. Twenty-four healthy participants (12 women) were tested in a randomized and counterbalanced design that consisted of three experimental protocols, each lasting 30 min: low-intensity exercise (Low-Int); moderate-intensity exercise (Mod-Int); and a seated rest condition (REST). After each of the protocols, participants viewed negative and positive pictures, during which event-related magnetic fields were recorded. Analyses revealed that exercise strongly impacted the valence processing of emotional scenes within a widely distributed left hemispheric spatio-temporal cluster between 190 and 310 ms after picture onset. Brain activity in this cluster showed that a negativity bias at REST (negative > positive picture processing) diminished after the Low-Int condition (positive = negative) and even reversed to a positivity bias after the Mod-Int condition (positive > negative). Thus, acute aerobic exercise of low and moderate intensities induces a positivity bias which is reflected in early, automatic processes.

Voluntary Exercise Suppresses Choroidal Neovascularization in Mice

Purpose

To determine the effect of voluntary exercise on choroidal neovascularization (CNV) in mice.

Methods

Age-matched wild-type C57BL/6J mice were housed in cages equipped with or without running wheels. After four weeks of voluntary running or sedentariness, mice were subjected to laser injury to induce CNV. After surgical recovery, mice were placed back in cages with or without exercise wheels for seven days. CNV lesion volumes were measured by confocal microscopy. The effect of wheel running only in the seven days after injury was also evaluated. Macrophage abundance and cytokine expression were quantified.

Results

In the first study, exercise-trained mice exhibited a 45% reduction in CNV volume compared to sedentary mice. In the replication study, a 32% reduction in CNV volume in exercise-trained mice was observed (P = 0.029). Combining these two studies, voluntary exercise was found to reduce CNV by 41% (P = 0.0005). Exercise-trained male and female mice had similar CNV volumes (P = 0.99). The daily running distance did not correlate with CNV lesion size. Exercise only after the laser injury without a preconditioning period did not reduce CNV size (P = 0.41). CNV lesions of exercise-trained mice also exhibited significantly lower F4/80+ macrophage staining and Vegfa and Ccl2 mRNA expression.

Conclusions

These findings provide the first experimental evidence that voluntary exercise improves CNV outcomes. These studies indicate that exercise before laser treatment is required to improve CNV outcomes.

Elimination of galanin synthesis in noradrenergic neurons reduces galanin in select brain areas and promotes active coping behaviors

Accumulating evidence indicates that disruption of galanin signaling is associated with neuropsychiatric disease, but the precise functions of this neuropeptide remain largely unresolved due to lack of tools for experimentally disrupting its transmission in a cell type-specific manner. To examine the function of galanin in the noradrenergic system, we generated and crossed two novel knock-in mouse lines to create animals lacking galanin specifically in noradrenergic neurons (Gal^cKO-Dbh). We observed reduced levels of galanin peptide in pons, hippocampus, and prefrontal cortex of Gal^cKO-Dbh mice, indicating that noradrenergic neurons are a significant source of galanin to those brain regions, while midbrain and hypothalamic galanin levels were comparable to littermate controls. In these same brain regions, we observed no change in levels of norepinephrine or its major metabolite at baseline or after an acute stressor, suggesting that loss of galanin does not affect noradrenergic synthesis or turnover. Gal^cKO-Dbh mice had normal performance in tests of depression, learning, and motor-related behavior, but had an altered response in some anxiety-related tasks. Specifically, Gal^cKO-Dbh mice showed increased marble and shock probe burying and had a reduced latency to eat in a novel environment, indicative of a more proactive coping strategy. Together, these findings indicate that noradrenergic neurons provide a significant source of galanin to discrete brain areas, and noradrenergic-specific galanin opposes adaptive coping responses.

Acute forced exercise increases Bdnf IV mRNA and reduces exploratory behavior in C57BL/6J mice

Acute exercise has been shown to improve memory in humans. Potential mechanisms include increased Bdnf expression, noradrenergic activity and modification of glutamate receptors. Because mice are commonly used to study exercise and brain plasticity, it is important to explore how acute exercise impacts behavior in this model. C57BL/6J mice were assigned to three groups: control, moderate-intensity running, and high-intensity running. Control mice were placed on a stationary treadmill for 30 minutes and moderate- and high-intensity mice ran for 30 minutes at 12 and 15-17 m/min, respectively. Mice were sacrificed immediately after running and the hippocampus removed. Total Bdnf, Bdnf exon IV, and glutamate receptor subunits were quantified with quantitative polymerase chain reaction. Total and phosphorylated GluR1 (Ser845 and Ser831) protein was quantified following immunoblotting. Utilizing the same protocol for control and high-intensity running, object location memory was examined in a separate cohort of mice. Anxiety-like behavior was assessed in the open field task (OFT) in a third cohort of mice that were separated into four groups: control-saline, control-DSP-4, acute exercise-saline, and acute exercise-DSP-4. DSP-4 was used to lesion the central noradrenergic system. We observed higher Bdnf IV mRNA in high-intensity runners compared to controls, but no effects of acute exercise on memory. In the OFT, runners traveled less distance and spent more time grooming than controls. DSP-4 did not attenuate the effects of exercise. A single bout of exercise increases Bdnf IV mRNA in an intensity-dependent manner; however, high-intensity running reduces exploratory behavior in C57BL/6J mice.

Poor Diet, Stress, and Inactivity Converge to Form a "Perfect Storm" That Drives Alzheimer's Disease Pathogenesis

North American incidence of Alzheimer's disease (AD) is expected to more than double over the coming generation. Although genetic factors surrounding the production and clearance of amyloid-β and phosphorylated tau proteins are known to be responsible for a subset of early-onset AD cases, they do not explain the pathogenesis of the far more prevalent sporadic late-onset variant of the disease. It is thus likely that lifestyle and environmental factors contribute to neurodegenerative processes implicated in the pathogenesis of AD. Herein, we review evidence that (1) excess sucrose consumption induces AD-associated liver pathologies and brain insulin resistance, (2) chronic stress overdrives activity of locus coeruleus neurons, leading to loss of function (a common event in neurodegeneration), (3) high-sugar diets and stress promote the loss of neuroprotective sex hormones in men and women, and (4) Western dietary trends set the stage for a lithium-deficient state. We propose that these factors may intersect as part of a "perfect storm" to contribute to the widespread prevalence of neurodegeneration and AD. In addition, we put forth the argument that exercise and supplementation with trace lithium can counteract many of the deleterious consequences associated with excessive caloric intake and perpetual stress. We conclude that lifestyle and environmental factors likely contribute to AD pathogenesis and that simple lifestyle and dietary changes can help counteract their effects.

Effects of sedentary behavior and physical activity on sleep quality in older people: A cross-sectional study

The aim of this cross-sectional study was to investigate the influence of replacing sedentary time with time engaged in one of two levels of physical activity on sleep quality using an isotemporal substitution model. The participants were 70 community-dwelling older Japanese adults (approximately 70% female). Physical activity types were measured using a triaxial accelerometer and categorized based on intensity as sedentary, light-intensity, and vigorous-intensity. The Pittsburgh Sleep Quality Index assessed subjective sleep quality. Objective sleep parameters were assessed using an actigraph. A series of multi-linear regression models analyzed the statistical relationships. Our findings showed that replacing 30 min of sedentary activity per day with an equal period of light-intensity physical activity significantly influenced sleep quality parameters. However, there was no significant difference in sleep quality when light-intensity activity was replaced with vigorous-intensity activity. Engaging in one activity type means less available time for other types of activity; habitual replacement of sedentary activity with light-intensity physical activity might have long-term benefits on the sleep quality of older people.

Odorants: a tool to provide nonpharmacological intervention to reduce anxiety during normal and pathological aging

Anxiety disorders represent 1 of the most common classes of psychiatric disorders. In the aging population and for patients with age-related pathology, the percentage of people suffering of anxiety is significantly elevated. Furthermore, anxiety carries with it an increased risk for a variety of age-related medical conditions, including cardiovascular disease, stroke, cognitive decline, and increased severity of motor symptoms in Parkinson's disease. A variety of anxiolytic compounds are available but often carry with them disturbing side effects that impact quality of life. Among nonmedicinal approaches to reducing anxiety, odor diffusion and aromatherapy are the most popular. In this review, we highlight the emerging perspective that the use of odorants may reduce anxiety symptoms or at least potentiate the effect of other anxiolytic approaches and may serve as an alternative form of therapy to deal with anxiety symptoms. Such approaches may be particularly beneficial in aging populations with elevated risk for these disorders. We also discuss potential neural mechanisms underlying the anxiolytic effects of odorants based on work in animal models.

Wheel-running exercise before and during gestation against acute and sensitized cocaine psychomotor-activation in offspring

While animal research has consistently reported preventive effects of exercise against drug abuse vulnerability, little is known about the influence of the developmental stage during which exercise is displayed on addictive drugs responsiveness. This study aimed to determine whether prenatal exercise could attenuate acute cocaine reactivity and psychomotor sensitization in youth offspring. We used a split-plot factorial design where C57BL/6 J females were randomly assigned into sedentary or exercised (wheel-running) conditions before and during gestation, the wheels being removed on gestational day 18. Offspring were weaned, gendered and individually housed on 24-28 days old. At 38-42 days old, they were tested for their acute psychomotor responsiveness to 8 mg/kg cocaine and their initiation of sensitization over 8 additional once-daily administrations, the long-term expression of sensitization occurring 30 days later. Adolescent females born from exercised mothers were much less responsive to the acute psychomotor-stimulating effect of cocaine than those born from sedentary mothers (d = 0.75, p = 0.02), whereas there was no evidence for such a difference in males (d = 0.34, p = 0.17). However, we did not find sizeable attenuating effects of prenatal exercise on the initiation and the long-term expression of the psychomotor-activating effect of cocaine, in either sex (Cohen's ds varying from -0.13 to 0.39). These results suggest that prenatal exercise may induce initial protection against cocaine responsiveness in youth females, a finding that warrants further research.

Voluntary exercise enables stress resistance in females

Stress-related disorders are more common in females than males. This difference could arise from differential responses to behavioral interventions that enable stress resistance between sexes. In male rats, regular physical activity prevents the behavioral consequences of uncontrollable stress, such as social avoidance and exaggerated fear conditioning. However, it is unknown if these protective effects are also present in females. Here we demonstrate for the first time in female rats that six weeks of voluntary wheel running buffers against the behavioral sequelae of uncontrollable stress. This observation allows for mechanistic investigations of exercise-induced stress resistance in both sexes.

Behavior of mice aboard the International Space Station

Interest in space habitation has grown dramatically with planning underway for the first human transit to Mars. Despite a robust history of domestic and international spaceflight research, understanding behavioral adaptation to the space environment for extended durations is scant. Here we report the first detailed behavioral analysis of mice flown in the NASA Rodent Habitat on the International Space Station (ISS). Following 4-day transit from Earth to ISS, video images were acquired on orbit from 16- and 32-week-old female mice. Spaceflown mice engaged in a full range of species-typical behaviors. Physical activity was greater in younger flight mice as compared to identically-housed ground controls, and followed the circadian cycle. Within 7-10 days after launch, younger (but not older), mice began to exhibit distinctive circling or 'race-tracking' behavior that evolved into coordinated group activity. Organized group circling behavior unique to spaceflight may represent stereotyped motor behavior, rewarding effects of physical exercise, or vestibular sensation produced via self-motion. Affording mice the opportunity to grab and run in the RH resembles physical activities that the crew participate in routinely. Our approach yields a useful analog for better understanding human responses to spaceflight, providing the opportunity to assess how physical movement influences responses to microgravity.

Brain Modulation by Electric Currents in Fibromyalgia: A Structured Review on Non-invasive Approach With Transcranial Electrical Stimulation

Fibromyalgia syndrome (FMS) is a complex disorder where widespread musculoskeletal pain is associated with many heterogenous symptoms ranging from affective disturbances to cognitive dysfunction and central fatigue. FMS is currently underdiagnosed and often very poorly responsive to pharmacological treatment. Pathophysiology of the disease remains still obscure even if in the last years fine structural and functional cerebral abnormalities have been identified, principally by neurophysiological and imaging studies delineating disfunctions in pain perception, processing and control systems. On such basis, recently, neurostimulation of brain areas involved in mechanism of pain processing and control (primary motor cortex: M1 and dorsolateral prefrontal cortex: DLPFC) has been explored by means of different approaches and particularly through non-invasive brain stimulation techniques (transcranial magnetic and electric stimulation: TMS and tES). Here we summarize studies on tES application in FMS. The great majority of reports, based on direct currents (transcranial direct currents stimulation: tDCS) and targeting M1, showed efficacy on pain measures and less on cognitive and affective symptoms, even if several aspects as maintenance of therapeutical effects and optimal stimulation parameters remain to be established. Differently, stimulation of DLPFC, explored in a few studies, was ineffective on pain and showed limited effects on cognitive and affective symptoms. Very recently new tES techniques as high-density tDCS (HD-tDCS), transcranial random noise stimulation (tRNS) and tDCS devices for home-based treatment have been explored in FMS with interesting even if very preliminary results opening interesting perspectives for more effective, well tolerated, cheap and easy therapeutic approaches.

Leisure time physical activity and incident use of prescription tranquilizers: A longitudinal population-based study

OBJECTIVE

Physical inactivity is a major public health problem associated with an increased risk of several psychiatric and physical conditions. This study investigated the association between leisure time physical activity (PA) and incident use of prescription tranquilizers in a regionally representative and prospective cohort.

METHODS

A total of 4043 men and women (mean age: 61.3 years; 57% women) from the Tromsø Study were followed for six years. Leisure time PA was captured at baseline. Psychiatric morbidity was measured by use of prescription tranquilizers, captured at both baseline and follow-up. Leisure time PA at baseline was used as a predictor of subsequent (incident) use of prescription tranquilizers. We used multinomial regression models and Poisson regression models to estimate relative risk-ratios (RRRs), and relative risks (RRs), respectively, and their corresponding 95% confidence intervals (CIs).

RESULTS

In the fully-adjusted model, accounting for socio-demographic factors, parental history of psychopathology, years of education, smoking, respondent's psychopathology at baseline, and occupational PA, a lower leisure time PA conferred a 41% increased risk of incident use of prescription tranquilizers at follow-up (RR = 1.41, 95% CI: 1.09, 1.83; p = 0.010).

CONCLUSIONS

These findings suggest that physical inactivity increases the risk of psychiatric morbidity (albeit, measured via use of prescription tranquilizers). Future regionally representative and longitudinal research is required to confirm/refute our findings and explore underlying mechanisms.

Exercise decreases defensive responses to unpredictable, but not predictable, threat

BACKGROUND

Research supports the anxiolytic effect of exercise, but the mechanism underlying this effect is unclear. This study examines the influence of exercise in healthy controls on two distinct defensive states implicated in anxiety disorders: fear, a phasic response to a predictable threat, and anxiety, a sustained response to an unpredictable threat.

METHODS

Thirty-four healthy volunteers (17 male, age M = 26.18, SD = 5.6) participated in sessions of exercise (biking at 60-70% of heart rate reserve) and control (biking at 10-20% of heart rate reserve) activity for 30 min, separated by 1 week. Threat responses were measured by eyeblink startle and assessed with the "Neutral-Predictable-Unpredictable threat test," which includes a neutral (N) and two threat conditions, one with predictable (P) and one with unpredictable (U) shock.

RESULTS

Results show that exercise versus control activity reduces startle potentiation during unpredictable threat (P = .031), but has no effect on startle potentiation during predictable threat (P = .609).

CONCLUSIONS

These results suggest that exercise reduces defensive response to unpredictable, but not predictable, threat, a dissociation that may help inform clinical indications for this behavioral intervention, as well as provide clues to its underlying neurobehavioral mechanisms.

The Impact of Exercise in Rodent Models of Chronic Pain

PURPOSE OF REVIEW

Physical activity is increasingly recommended for chronic pain. In this review, we briefly survey recent, high-quality meta-analyses on the effects of exercise in human chronic pain populations, followed by a critical discussion of the rodent literature.

RECENT FINDINGS

Most meta-analytical studies on the effects of exercise in human chronic pain populations describe moderate improvements in various types of chronic pain, despite substantial variability in the outcomes reported in the primary literature. The most consistent findings suggest that while greater adherence to exercise programs produces better outcomes, there is minimal support for the superiority of one type of exercise over another. The rodent literature similarly suggests that while regular exercise reduces hypersensitivity in rodent models of chronic pain, exercise benefits do not appear to relate to either the type of injury or any particular facet of the exercise paradigm. Potential factors underlying these results are discussed, including the putative involvement of stress-induced analgesic effects associated with certain types of exercise paradigms. Exercise research using rodent models of chronic pain would benefit from increased attention to the role of stress in exercise-induced analgesia, as well as the incorporation of more clinically relevant exercise paradigms.

Immune and Neuroprotective Effects of Physical Activity on the Brain in Depression

Physical activity-a lifestyle factor that is associated with immune function, neuroprotection, and energy metabolism-modulates the cellular and molecular processes in the brain that are vital for emotional and cognitive health, collective mechanisms that can go awry in depression. Physical activity optimizes the stress response, neurotransmitter level and function (e.g., serotonergic, noradrenergic, dopaminergic, and glutamatergic), myokine production (e.g., interleukin-6), transcription factor levels and correlates [e.g., peroxisome proliferator-activated receptor C coactivator-1α [PGC-1α], mitochondrial density, nitric oxide pathway activity, Ca2+ signaling, reactive oxygen specie production, and AMP-activated protein kinase [AMPK] activity], kynurenine metabolites, glucose regulation, astrocytic health, and growth factors (e.g., brain-derived neurotrophic factor). Dysregulation of these interrelated processes can effectuate depression, a chronic mental illness that affects millions of individuals worldwide. Although the biogenic amine model has provided some clinical utility in understanding chronic depression, a need remains to better understand the interrelated mechanisms that contribute to immune dysfunction and the means by which various therapeutics mitigate them. Fortunately, convergent evidence suggests that physical activity improves emotional and cognitive function in persons with depression, particularly in those with comorbid inflammation. Accordingly, the aims of this review are to (1) underscore the link between inflammatory correlates and depression, (2) explicate immuno-neuroendocrine foundations, (3) elucidate evidence of neurotransmitter and cytokine crosstalk in depressive pathobiology, (4) determine the immunomodulatory effects of physical activity in depression, (5) examine protocols used to effectuate the positive effects of physical activity in depression, and (6) highlight implications for clinicians and scientists. It is our contention that a deeper understanding of the mechanisms by which inflammation contributes to the pathobiology of depression will translate to novel and more effective treatments, particularly by identifying relevant patient populations that can benefit from immune-based therapies within the context of personalized medicine.

Chronic forced exercise inhibits stress-induced reinstatement of cocaine conditioned place preference

Stress increases the likelihood of cocaine relapse in humans and animals, even following a prolonged extinction/abstinence period. Exercise has previously been shown to reduce stress and decrease the likelihood of drug dependence, while also reducing cravings in humans and inhibiting relapse behaviors due to other risk factors in rodents. The present study evaluated the efficacy of exercise to reduce stress-induced relapse to cocaine in a rodent model. Young adult female Sprague Dawley rats were tested for cocaine conditioned place preference (CPP), then split into sedentary or exercise (six weeks of one-hour daily treadmill running, five days per week) groups. Following cocaine CPP, rats were tested for extinction behavior, and then tested for stress-primed reinstatement (15 min immobilization) following the six-week intervention period. Exercise inhibited stress-induced reinstatement of cocaine CPP despite increasing serum corticosterone levels following 15 min of immobilization, suggesting that chronic aerobic exercise intervention may result in adaptations of stress pathways. These findings suggest that exercise may help prevent stress-induced drug relapse, adding to a growing body of evidence supporting the utility of exercise to combat substance abuse.

Running from fear: Exercise modulation of fear extinction

Extinction-based exposure therapy is the most common behavioral therapy for anxiety and trauma-related disorders, but fear tends to resurface even after successful extinction. Identification of novel strategies to enhance fear extinction and reduce fear relapse is of paramount importance to mental health. Exercise can enhance cognitive function, but it is not yet well understood whether exercise can be an effective augmentation strategy for fear extinction. In the current review, we present the current state of knowledge on the effects of exercise on fear extinction. Effects of exercise duration, explanations for conflicting results, and potential mechanisms, focusing on a hypothesized role for dopamine, are all discussed. We also provide new data suggesting that the timing in which acute exercise occurs relative to fear extinction, is a crucial variable in determining whether exercise can enhance fear extinction. Clinical implications and ideas to guide future research endeavors in this area are provided.

How Does Exercise Reduce the Rate of Age-Associated Cognitive Decline? A Review of Potential Mechanisms

The rate of age-associated cognitive decline varies considerably between individuals. It is important, both on a societal and individual level, to investigate factors that underlie these differences in order to identify those which might realistically slow cognitive decline. Physical activity is one such factor with substantial support in the literature. Regular exercise can positively influence cognitive ability, reduce the rate of cognitive aging, and even reduce the risk of Alzheimer's disease (AD) and other dementias. However, while there is substantial evidence in the extant literature for the effect of exercise on cognition, the processes that mediate this relationship are less clear. This review examines cardiovascular health, production of brain derived neurotrophic factor (BDNF), insulin sensitivity, stress, and inflammation as potential pathways, via which exercise may maintain or improve cognitive functioning, and may be particularly pertinent in the context of the aging brain. A greater understanding of these mechanisms and their potential relationships with exercise and cognition will be invaluable in providing biomarkers for investigating the efficacy of differing exercise regimes on cognitive outcomes.

Variant BDNF-Val66Met Polymorphism is Associated with Layer-Specific Alterations in GABAergic Innervation of Pyramidal Neurons, Elevated Anxiety and Reduced Vulnerability of Adolescent Male Mice to Activity-Based Anorexia

Previously, we determined that rodents' vulnerability to food restriction (FR)-evoked wheel running during adolescence (activity-based anorexia, ABA) is associated with failures to increase GABAergic innervation of hippocampal and medial prefrontal pyramidal neurons. Since brain-derived neurotrophic factor (BDNF) promotes GABAergic synaptogenesis, we hypothesized that individual differences in this vulnerability may arise from differences in the link between BDNF bioavailability and FR-evoked wheel running. We tested this hypothesis in male BDNF-Val66Met knock-in mice (BDNFMet/Met), known for reduction in the activity-dependent BDNF secretion and elevated anxiety-like behaviors. We found that 1) in the absence of FR or a wheel (i.e., control), BDNFMet/Met mice are more anxious than wild-type (WT) littermates, 2) electron microscopically verified GABAergic innervations of pyramidal neurons of BDNFMet/Met mice are reduced at distal dendrites in hippocampal CA1 and medial prefrontal cortex, 3) following ABA, WT mice exhibit anxiety equal to those of the BDNFMet/Met mice and have lost GABAergic innervation along distal dendrites, 4) BDNFMet/Met mice show blunted ABA vulnerability, and 5) unexpectedly, GABAergic innervation is higher at somata of BDNFMet/Met mice than of WT. We conclude that lamina-specific GABAergic inhibition is important for regulating anxiety, whether arising from environmental stress, such as food deprivation, or genetically, such as BDNFMet/Met single nucleotide polymorphism.

Exercise increases mTOR signaling in brain regions involved in cognition and emotional behavior

Exercise can enhance learning and memory and produce resistance against stress-related psychiatric disorders such as depression and anxiety. In rats, these beneficial effects of exercise occur regardless of exercise controllability: both voluntary and forced wheel running produce stress-protective effects. The mechanisms underlying these beneficial effects of exercise remain unknown. The mammalian target of rapamycin (mTOR) is a translation regulator important for cell growth, proliferation, and survival. mTOR has been implicated in enhancing learning and memory as well as antidepressant effects. Moreover, mTOR is sensitive to exercise signals such as metabolic factors. The effects of exercise on mTOR signaling, however, remain unknown. The goal of the present study was to test the hypothesis that exercise, regardless of controllability, increases levels of phosphorylated mTOR (p-mTOR) in brain regions important for learning and emotional behavior. Rats were exposed to 6 weeks of either sedentary (locked wheel), voluntary, or forced wheel running conditions. At 6 weeks, rats were sacrificed during peak running and levels of p-mTOR were measured using immunohistochemistry. Overall, both voluntary and forced exercise increased p-mTOR-positive neurons in the medial prefrontal cortex, striatum, hippocampus, hypothalamus, and amygdala compared to locked wheel controls. Exercise, regardless of controllability, also increased numbers of p-mTOR-positive glia in the striatum, hippocampus, and amygdala. For both neurons and glia, the largest increase in p-mTOR positive cells was observed after voluntary running, with forced exercise causing a more modest increase. Interestingly, voluntary exercise preferentially increased p-mTOR in astrocytes (GFAP+), while forced running increased p-mTOR in microglia (CD11+) in the inferior dentate gyrus. Results suggest that mTOR signaling is sensitive to exercise, but subtle differences exist depending on exercise controllability. Increases in mTOR signaling could contribute to the beneficial effects of exercise on cognitive function and mental health.

Synaptic changes in the hippocampus of adolescent female rodents associated with resilience to anxiety and suppression of food restriction-evoked hyperactivity in an animal model for anorexia nervosa

Anorexia nervosa is a mental illness that emerges primarily during early adolescence, with mortality rate that is 200 times higher than that of suicide. The illness is characterized by intense fear of gaining weight, heightened anxiety, obstinate food restriction, often accompanied by excessive exercise, in spite of mounting hunger. The illness affects females nine times more often than males, suggesting an endocrine role in its etiology. Its relapse rate exceeds 25%, yet there are no accepted pharmacological treatments to prevent this. Here, we summarize studies from this laboratory that have used adolescent female rodents in activity-based anorexia (ABA), an animal model of anorexia nervosa, with the goal of identifying neurobiological underpinnings of this disease. We put forth a hypothesis that a GABAergic mechanism within the hippocampus is central to regulating an individual׳s anxiety which, in turn, strongly influences the individual׳s resilience/vulnerability to ABA. In particular, we propose that ionotropic GABAA receptors containing the subunits alpha4 and delta, are at play for exerting shunting inhibition upon hippocampal pyramidal neurons that become more excitable during ABA. Since these receptors confer insensitivity to benzodiazepines, this pharmacological profile of ABA fits with lack of report indicating efficacy of benzodiazepines in reducing the anxiety experienced by individuals with anorexia nervosa. The idea that the GABAergic system of the hippocampus regulates resilience/vulnerability to anorexia nervosa complements current opinions about the important roles of the prefrontal cortex, amygdala, striatum, gustatory pathways and feeding centers of the hypothalamus and of the neuromodulators, serotonin and dopamine, in the etiology of the disease. This article is part of a Special Issue entitled SI: Adolescent plasticity.

Neuroprotective Effects of Exercise Treatments After Injury: The Dual Role of Neurotrophic Factors

BACKGROUND

Shared connections between physical activity and neuroprotection have been studied for decades, but the mechanisms underlying this effect of specific exercise were only recently brought to light. Several evidences suggest that physical activity may be a reasonable and beneficial method to improve functional recovery in both peripheral and central nerve injuries and to delay functional decay in neurodegenerative diseases. In addition to improving cardiac and immune functions, physical activity may represent a multifunctional approach not only to improve cardiocirculatory and immune functions, but potentially modulating trophic factors signaling and, in turn, neuronal function and structure at times that may be critical for neurodegeneration and regeneration.

METHODS

Research content related to the effects of physical activity and specific exercise programs in normal and injured nervous system have been reviewed.

RESULTS

Sustained exercise, particularly if applied at moderate intensity and early after injury, exerts anti-inflammatory and pro-regenerative effects, and may boost cognitive and motor functions in aging and neurological disorders. However, newest studies show that exercise modalities can differently affect the production and function of brain-derived neurotrophic factor and other neurotrophins involved in the generation of neuropathic conditions. These findings suggest the possibility that new exercise strategies can be directed to nerve injuries with therapeutical benefits.

CONCLUSION

Considering the growing burden of illness worldwide, understanding of how modulation of neurotrophic factors contributes to exercise-induced neuroprotection and regeneration after peripheral nerve and spinal cord injuries is a relevant topic for research, and represents the beginning of a new non-pharmacological therapeutic approach for better rehabilitation of neural disorders.

Depression-like behavior in rat: Involvement of galanin receptor subtype 1 in the ventral periaqueductal gray

The neuropeptide galanin coexists in rat brain with serotonin in the dorsal raphe nucleus and with noradrenaline in the locus coeruleus (LC), and it has been suggested to be involved in depression. We studied rats exposed to chronic mild stress (CMS), a rodent model of depression. As expected, these rats showed several endophenotypes relevant to depression-like behavior compared with controls. All these endophenotypes were normalized after administration of a selective serotonin reuptake inhibitor. The transcripts for galanin and two of its receptors, galanin receptor 1 (GALR1) and GALR2, were analyzed with quantitative real-time PCR using laser capture microdissection in the following brain regions: the hippocampal formation, LC, and ventral periaqueductal gray (vPAG). Only Galr1 mRNA levels were significantly increased, and only in the latter region. After knocking down Galr1 in the vPAG with an siRNA technique, all parameters of the depressive behavioral phenotype were similar to controls. Thus, the depression-like behavior in rats exposed to CMS is likely related to an elevated expression of Galr1 in the vPAG, suggesting that a GALR1 antagonist could have antidepressant effects.

Central monoaminergic systems are a site of convergence of signals conveying the experience of exercise to brain circuits involved in cognition and emotional behavior

Physical activity can enhance cognitive function and increase resistance against deleterious effects of stress on mental health. Enhanced cognitive function and stress resistance produced by exercise are conserved among vertebrates, suggesting that ubiquitous mechanisms may underlie beneficial effects of exercise. In the current review, we summarize the beneficial effects of exercise on cognitive function and stress resistance and discuss central and peripheral signaling factors that may be critical for conferring the effects of physical activity to brain circuits involved in cognitive function and stress. Additionally, it is suggested that norepinephrine and serotonin, highly conserved monoamines that are sensitive to exercise and able to modulate behavior in multiple species, could represent a convergence between peripheral and central exercise signals that mediate the beneficial effects of exercise. Finally, we offer the novel hypothesis that thermoregulation during exercise could contribute to the emotional effects of exercise by activating a subset of temperature-sensitive serotonergic neurons in the dorsal raphe nucleus that convey anxiolytic and stress-protective signals to forebrain regions. Throughout the review, we discuss limitations to current approaches and offer strategies for future research in exercise neuroscience.

Cerebellar sub-divisions differ in exercise-induced plasticity of noradrenergic axons and in their association with resilience to activity-based anorexia

The vermis or "spinocerebellum" receives input from the spinal cord and motor cortex for controlling balance and locomotion, while the longitudinal hemisphere region or "cerebro-cerebellum" is interconnected with non-motor cortical regions, including the prefrontal cortex that underlies decision-making. Noradrenaline release in the cerebellum is known to be important for motor plasticity but less is known about plasticity of the cerebellar noradrenergic (NA) system, itself. We characterized plasticity of dopamine β-hydroxylase-immunoreactive NA fibers in the cerebellum of adolescent female rats that are evoked by voluntary wheel running, food restriction (FR) or by both, in combination. When 8 days of wheel access was combined with FR during the last 4 days, some responded with excessive exercise, choosing to run even during the hours of food access: this exacerbated weight loss beyond that due to FR alone. In the vermis, exercise, with or without FR, shortened the inter-varicosity intervals and increased varicosity density along NA fibers, while excessive exercise, due to FR, also shortened NA fibers. In contrast, the hemisphere required the FR-evoked excessive exercise to evoke shortened inter-varicosity intervals along NA fibers and this change was exhibited more strongly by rats that suppressed the FR-evoked excessive exercise, a behavior that minimized weight loss. Presuming that shortened inter-varicosity intervals translate to enhanced NA release and synthesis of norepinephrine, this enhancement in the cerebellar hemisphere may contribute towards protection of individuals from the life-threatening activity-based anorexia via relays with higher-order cortical areas that mediate the animal's decision to suppress the innate FR-evoked hyperactivity.