Acute BDNF and cortisol response to low intensity exercise and following ramp incremental exercise to exhaustion in humans

Acute running stimulates hippocampal dopaminergic neurotransmission in rats, but has no influence on brain-derived neurotrophic factor

Hippocampal brain-derived neurotrophic factor (BDNF) protein is increased with exercise in rats. Monoamines seem to play a role in the regulation of BDNF, and monoamine neurotransmission is known to increase with exercise. The purpose of this study was to examine the influence of acute exercise on monoaminergic neurotransmission and BDNF protein concentrations. Hippocampal microdialysis was performed in rats that were subjected to 60 min of treadmill running at 20 m/min or rest. Two hours postexercise, the rats were killed, and the hippocampus was dissected. In experiments without microdialysis, hippocampus and serum samples were collected immediately after exercise. Exercise induced a twofold increase in hippocampal dopamine release. Noradrenaline and serotonin release were not affected. Hippocampal BDNF levels were not influenced, whether they were measured immediately or 2 h after the exercise protocol. Serum BDNF levels did not change either, but serum BDNF was negatively correlated to peripheral corticosterone concentrations, indicating a possible inhibitory reaction to the stress of running. Sixty minutes of exercise enhances dopamine release in the hippocampus of the rat in vivo. However, this increase is not associated with changes in BDNF protein levels immediately nor 2 h after the acute exercise bout. An increased corticosterone level might be the contributing factor for the absence of changes in BDNF.

Serum NPY and BNDF response to a behavioral stressor in alcohol-dependent and healthy control participants

RATIONALE

Neuropeptide Y (NPY) and brain-derived neurotrophic factor (BDNF) have been implicated in both the stress response and alcohol addiction. However, few studies have assessed the NPY and BDNF response to stress in alcohol-dependent participants and the concurrent measure of NPY and BDNF has not been reported in human participants.

OBJECTIVE

The purpose of this study was to concurrently assess serum NPY and BDNF, as well as adrenocorticotropin (ACTH) and cortisol, in control and race- and aged-matched abstinent alcohol-dependent participants in response to a stress-inducing public-speaking task.

METHODS

Basal and post-stress serum values of NPY and BDNF, as well as ACTH and cortisol, were assessed in 14 abstinent alcohol-dependent and ten healthy control male participants.

RESULTS

Basal measures were stable over short periods of time and stress induced a significant increase in both NPY (p = 0.002) and BDNF (p = 0.006) as well as ACTH (p < 0.001) and cortisol (p < 0.007). Alcohol-dependent and control groups did not significantly differ on any basal or stress-induced measure. Basal and delta responses of NPY and BDNF were not significantly correlated, and delta peak responses of NPY and BDNF did not correlate with one another or with their respective ACTH and cortisol responses.

CONCLUSIONS

These findings reveal that both serum NPY and BDNF are responsive to behavioral stressors, although their regulatory mechanisms appear to differ from one another and those of the hypothalamic-pituitary-adrenal axis. Differences in basal and stress-induced responses of NPY and BDNF were not supported between control and abstinent alcohol-dependent subjects.

Serum levels of brain-derived neurotrophic factor in major depressive disorder: state-trait issues, clinical features and pharmacological treatment

Recent evidence supports 'the neurotrophin hypothesis of depression' in its prediction that brain-derived neurotrophic factor (BDNF) is involved in depression. However, some key questions remain unanswered, including whether abnormalities in BDNF persist beyond the clinical state of depression, whether BDNF levels are related to the clinical features of depression and whether distinct antidepressants affect BDNF levels equally. We addressed these questions and investigated serum BDNF levels in 962 depressed patients, 700 fully remitted persons (≥6 months) and 382 healthy controls. We found serum BDNF levels to be low in antidepressant-free depressed patients relative to controls (P=0.007) and to depressed patients who were treated with an antidepressant (P=0.001). BDNF levels of fully remitted persons (whether unmedicated or treated with an antidepressant) were comparable to those of controls. Analyzing the sample of antidepressant-free depressed patients showed that BDNF levels were unrelated to the core clinical features of depression such as its severity or first versus a recurrent episode. The antidepressant associated upregulation of serum BDNF in depressed patients was confined to selective serotonin reuptake inhibitors (SSRIs) (P=0.003) and St John's wort (P=0.03). Our results suggest that low serum levels of BDNF are a state abnormality that is evident during depression and normalizes during remission. Increases in serum levels of BDNF during antidepressant treatment appear to be confined to some antidepressants and do not parallel clinical characteristics, such as the severity of depressive symptoms.

The recent understanding of the neurotrophin's role in skeletal muscle adaptation

This paper summarizes the various effects of neurotrophins in skeletal muscle and how these proteins act as potential regulators of the maintenance, function, and regeneration of skeletal muscle fibers. Increasing evidence suggests that this family of neurotrophic factors influence not only the survival and function of innervating motoneurons but also the development and differentiation of myoblasts and muscle fibers. Muscle contractions (e.g., exercise) produce BDNF mRNA and protein in skeletal muscle, and the BDNF seems to play a role in enhancing glucose metabolism and may act for myokine to improve various brain disorders (e.g., Alzheimer's disease and major depression). In adults with neuromuscular disorders, variations in neurotrophin expression are found, and the role of neurotrophins under such conditions is beginning to be elucidated. This paper provides a basis for a better understanding of the role of these factors under such pathological conditions and for treatment of human neuromuscular disease.

Physical exercise as a preventive or disease-modifying treatment of dementia and brain aging

A rapidly growing literature strongly suggests that exercise, specifically aerobic exercise, may attenuate cognitive impairment and reduce dementia risk. We used PubMed (keywords exercise and cognition) and manuscript bibliographies to examine the published evidence of a cognitive neuroprotective effect of exercise. Meta-analyses of prospective studies documented a significantly reduced risk of dementia associated with midlife exercise; similarly, midlife exercise significantly reduced later risks of mild cognitive impairment in several studies. Among patients with dementia or mild cognitive impairment, randomized controlled trials (RCTs) documented better cognitive scores after 6 to 12 months of exercise compared with sedentary controls. Meta-analyses of RCTs of aerobic exercise in healthy adults were also associated with significantly improved cognitive scores. One year of aerobic exercise in a large RCT of seniors was associated with significantly larger hippocampal volumes and better spatial memory; other RCTs in seniors documented attenuation of age-related gray matter volume loss with aerobic exercise. Cross-sectional studies similarly reported significantly larger hippocampal or gray matter volumes among physically fit seniors compared with unfit seniors. Brain cognitive networks studied with functional magnetic resonance imaging display improved connectivity after 6 to 12 months of exercise. Animal studies indicate that exercise facilitates neuroplasticity via a variety of biomechanisms, with improved learning outcomes. Induction of brain neurotrophic factors by exercise has been confirmed in multiple animal studies, with indirect evidence for this process in humans. Besides a brain neuroprotective effect, physical exercise may also attenuate cognitive decline via mitigation of cerebrovascular risk, including the contribution of small vessel disease to dementia. Exercise should not be overlooked as an important therapeutic strategy.

A review of weight control strategies and their effects on the regulation of hormonal balance

The estimated prevalence of obesity in the USA is 72.5 million adults with costs attributed to obesity more than 147 billion dollars per year. Though caloric restriction has been used extensively in weight control studies, short-term success has been difficult to achieve, with long-term success of weight control being even more elusive. Therefore, novel approaches are needed to control the rates of obesity that are occurring globally. The purpose of this paper is to provide a synopsis of how exercise, sleep, psychological stress, and meal frequency and composition affect levels of ghrelin, cortisol, insulin GLP-1, and leptin and weight control. We will provide information regarding how hormones respond to various lifestyle factors which may affect appetite control, hunger, satiety, and weight control.

Aerobic exercise improves hippocampal function and increases BDNF in the serum of young adult males

Physical activity has been reported to improve cognitive function in humans and rodents, possibly via a brain-derived neurotrophic factor (BDNF)-regulated mechanism. In this study of human subjects, we have assessed the effects of acute and chronic exercise on performance of a face-name matching task, which recruits the hippocampus and associated structures of the medial temporal lobe, and the Stroop word-colour task, which does not, and have assessed circulating concentrations of BDNF and IGF-1 in parallel. The results show that a short period of high-intensity cycling results in enhancements in performance of the face-name matching, but not the Stroop, task. These changes in cognitive function were paralleled by increased concentration of BDNF, but not IGF-1, in the serum of exercising subjects. 3 weeks of cycling training had no effect on cardiovascular fitness, as assessed by VO2 scores, cognitive function, or serum BDNF concentration. Increases in fitness, cognitive function and serum BDNF response to acute exercise were observed following 5 weeks of aerobic training. These data indicate that both acute and chronic exercise improve medial temporal lobe function concomitant with increased concentrations of BDNF in the serum, suggesting a possible functional role for this neurotrophic factor in exercise-induced cognitive enhancement in humans.

Physical therapy intervention (PTI) increases plasma brain-derived neurotrophic factor (BDNF) levels in non-frail and pre-frail elderly women

Biomarkers are important factors in the identification of the frail elderly (higher risk of developing disease) and in assessing the impact of PTI. On the other hand, BDNF has been related to neuroprotection in a series of central nervous system diseases in older age. The levels of BDNF in groups of elderly women classified according to Fried phenotype (non-frail and pre-frail) were compared. We assessed the impact of a PTI on BDNF levels. A convenience sample of 48 elderly women was randomly selected. The PTI group was composed by 20 elderly women selected from this group. Plasma neurotrophic factors, such as BDNF, glial-derived neutrophic factor (GDNF), and nerve growth factor (NGF) were measured by enzyme-linked immunosorbent assay (ELISA). Timed-up-and-go (TUG) test, hand-grip and work/body weight were evaluated before and after the intervention. Plasma concentrations of BDNF were significantly higher in non-frail in comparison to pre-frail elderly women. After the PTI, higher levels of BDNF were found in elderly women (before 351±68 pg/ml and after 593±79 pg/ml; p<0.001). Both groups had an increase in BDNF levels after the PTI. The low levels of BDNF in pre-frail elderly women suggest that this neurotrophic factor may be a key pathophysiological mediator in the syndrome of frailty. The fact that PTI increased BDNF levels in both groups suggests that it may be possible to modify this phenotype.

FIT Kids: Time in target heart zone and cognitive performance

OBJECTIVE

This present study examined time spent in the target heart zone (THZ) and its relationship to tasks requiring variable amounts of executive control function in prepubescent children participating in a 9-month randomized controlled physical activity program.

METHODS

A sample of 59 participants performed the Stroop Color-Word Test and the Comprehensive Trail Making Test cognitive assessments. Heart rate data were collected during participation in the physical activity program using E600 heart rate monitors (Polar, Finland).

RESULTS

There was a significant difference, F(1, 58)=7.44, p <.009, between males and females for relative VO2max, but not absolute (p=.69) or percent VO2max (p=.73). Regression analysis identified KBIT, age, and mean time above the THZ as significant predictors of performance in the Stroop Color-Word condition, F(1, 56)=5.21, p=.02. KBIT and mean time above the THZ were significant predictors for Trails B, F(1, 56)=7.60.

CONCLUSIONS

These results suggest that heart rate, as a measure of physical activity intensity, should be closely monitored during research that is intended to make inferences about its effects on cognitive performance as participation in vigorous activities may have specific benefits over lower intensities among prepubescent children.

Effects of brain-derived neurotrophic factor Val66Met polymorphism on hippocampal volume change in schizophrenia

A functional polymorphism of the brain-derived neurotrophic factor (BDNF) gene (Val66Met) has been associated with the risk for schizophrenia and volume differences in the hippocampus. However, little is known about the association between progressive brain volume change in schizophrenia and BDNF genotype. The aim of this study was to investigate the relationship between hippocampal volume change in patients with schizophrenia and healthy control subjects and BDNF genotype. Two structural magnetic resonance imaging brain scans were acquired of 68 patients with schizophrenia and 83 healthy subjects with an interval of approximately 5 yrs. Hippocampal volume change was measured and related to BDNF genotype in patients and healthy controls. BDNF genotype was not associated with hippocampal volume change over time in patients or healthy controls, nor could we replicate earlier findings on smaller hippocampal volume in Met-carriers. However, we did find a genotype-by-diagnosis interaction at baseline demonstrating smaller hippocampal volumes in patients homozygous for the Val-allele relative to healthy Val-homozygotes. In addition, irrespective of genotype, patients showed smaller hippocampal volumes compared with healthy controls at baseline. In summary, our results suggest that the BDNF Val66Met polymorphism is not associated with hippocampal volume change over time. Nevertheless, our findings may support the possibility that BDNF affects brain morphology differently in schizophrenia patients and healthy subjects.

Decreased serum brain-derived neurotrophic factor concentration in young nonobese subjects with low insulin sensitivity

OBJECTIVE

Insulin resistance and type 2 diabetes are associated with an increased risk of neurodegenerative diseases. Decreased brain-derived neurotrophic factor (BDNF) levels might play a role in the pathogenesis of neuropsychiatric disorders. The aim of our study was to estimate serum BDNF concentration in nonobese women divided into subgroups according to their insulin sensitivity.

DESIGN AND METHODS

We studied 46 young, healthy, nonobese women. Insulin sensitivity was estimated with the euglycemic-hyperinsulinemic clamp technique. Then, participants were divided into subgroups of high (mean, 12.79±2.01mg/kg fat-free mass/min) and low insulin sensitivity (mean, 7.33±1.66mg/kg fat-free mass/min).

RESULTS

We observed decreased serum BDNF concentration in women with low insulin sensitivity in comparison to high insulin sensitivity group (3306.11±603.10 vs 4141.91±755.37pg/mL, p=0.001). Serum BDNF was positively related to insulin sensitivity (r=0.43, p=0.003). This correlation remained significant after adjustment for other estimated parameters.

CONCLUSIONS

Serum BDNF is decreased in young nonobese women with low insulin sensitivity. Early detection and prevention of insulin resistance might be useful in the prevention of neurodegenerative disorders.

Influence of citalopram and environmental temperature on exercise-induced changes in BDNF

PURPOSE

Serum brain-derived neurotrophic factor (BDNF) is known to increase with exercise. This increase is believed to originate from the brain and it is suggested that monoamines are involved in BDNF regulation. Heat exposure could influence the supposed BDNF output from the brain. Therefore, we hypothesized that administration of a selective serotonin reuptake inhibitor could influence the exercise-induced increase in BDNF, and that peripheral BDNF will be higher when exercise is performed in the heat.

METHODS

Eleven well-trained males performed 4 experimental trials on a cycle ergometer with citalopram or placebo treatment (20 mg in 12 h) in an environmental temperature of 18°C or 30°C. Blood samples (BDNF and cortisol) were taken at 4 time points: at rest, after 60 min at 55% W(max), after a time trial of 30 min at 75% W(max) and following 15 min of recovery. Heart rate and core temperature were measured.

RESULTS

Performance on the time trial was 20% worse in 30°C compared to 18°C (p<0.01), without influence of citalopram. Serum BDNF was found to be lower under citalopram treatment, while basal cortisol levels were increased (p<0.05). Exercise triggered an increase in both BDNF and cortisol (p<0.001). BDNF followed the same pattern as core temperature during exercise, with higher levels of both variables in 30°C. Cortisol was also increased in 30°C compared to temperate conditions (p<0.01).

CONCLUSION

Exercise caused a rise in serum BDNF and cortisol. This increase was enhanced with exercise in the heat. Since permeability of the blood-brain barrier increases with exercise in the heat, the hypothesis was raised that this causes a higher cerebral output of BDNF. Serotonergic stimulation did not increase peripheral BDNF, which was even lower with citalopram administration. Future research should focus on mechanisms behind BDNF increase with exercise.

Responses of serum neurotrophic factors to exercise in pregnant and postpartum women

It was recently shown in humans that exercise affects the neurotrophic factors known to function as neurogenesis regulators. No data related to exercise and pregnancy, however, is yet available. Thus, we investigated the effects of acute exercise on pregnant women during late pregnancy and women postpartum, on the serum concentration of the brain-derived neurotrophic factor (BDNF), the insulin-like growth factor 1 (IGF-1), the vascular endothelial growth factor (VEGF), prolactin (PRL) and cortisol (COR). Twenty women with uncomplicated pregnancies underwent a graded submaximal exercise test during pregnancy (weeks 32-36 of gestation; T(1)) and postpartum (10-12 weeks after childbirth; T(2)). On two of these test days the women carried out an intensifying exercise test (25 W steps) on a cycle ergometer until a heart rate of 150 bpm was reached. Blood samples were taken in the rest period before beginning the exercise, immediately at the end of the exercise and after recovery periods of 5 and 10 min, respectively. Basal maternal IGF-1, PRL and COR were found to be higher during T(1) (p<.01), while the BDNF was higher during T(2) (p=.00). VEGF was not detectable in the serum of the pregnant women. During T(2), VEGF, which was found to be within the normal range before exercise, was at a higher level after exercise (p<.01). Exercise increased the BDNF and IGF-1 during T(1) and T(2) (p<.01). This study also shows that exercise increases the serum concentrations of IGF-1 and BDNF during pregnancy and postpartum as well as VEGF postpartum. Thus, exercise might be a beneficial lifestyle factor with therapeutic/public health implications i.e. with regard to maternal mood and cognitive performance.

Lactate infusion at rest increases BDNF blood concentration in humans

Studies in humans use blood lactate to determine the degree of the exercise intensity, suggesting that exercise with elevated blood lactate concentrations results in increased BDNF plasma concentrations. However, it is not clear if lactate per se or rather other mechanisms are responsible for changes in blood BDNF concentrations. The lactate clamp method at rest is an appropriate method to examine physiological responses of lactate on the human organism without the effects of exercise. Eight male sport students placed in a sitting position received intravenous infusions with a 4 molar sodium-lactate solution in an incremental design starting with an infusion rate of 0.01ml/kgBW/min for the first three minutes, which was increased every three minutes by 0.01ml/kgBW/min up to 0.08ml/kg/min in the 24th minute. All together each subject received 4.2mmol of infusion. Venous blood samples were taken before and immediately after the infusion as well as in the 24th and the 60th min after the infusion period and analysed for BDNF. Blood gases and capillary blood lactate (La) were analysed before the test, every three minutes directly before increasing the infusion rate, at the end of the infusion and in the post infusions period until the 12th min and after 24 and 60min. BDNF and La increased significantly after the infusion and reached baseline values at the end of the experiment (p<0.05, p<0.01, respectively). pH and hydrogen ions increased from the beginning until the end of the infusion period (p<0.01). This data suggest that blood lactate is involved in the regulation of BDNF blood concentrations.

Serum brain-derived neurotrophic factor predicts responses to escitalopram in chronic posttraumatic stress disorder

INTRODUCTION

Some studies have found that antidepressants increase serum brain-derived neurotrophic factor (BDNF) levels in patients with major depression and the expression of BDNF mRNA in limbic structures of rats.

OBJECTIVES

This study addressed whether the SSRI escitalopram increases serum BDNF levels in subjects with PTSD and whether BDNF levels are associated with treatment response.

METHODS

Medically healthy male subjects (N=16) with chronic PTSD completed a 12 week open-label trial of flexible dose (5-20 mg/day) escitalopram monotherapy. BDNF levels were obtained at baseline, and at weeks 4, 8 and 12.

RESULTS

PTSD symptoms significantly declined over the course of the 12 week escitalopram treatment. Despite a substantial improvement in PTSD symptoms, there was virtually no change in BDNF levels over time. Nevertheless, mean BDNF levels across the trial were strongly correlated with the slope of PTSD symptoms over the 12 weeks (r=0.58, p=0.018). Lower mean BDNF was associated with a greater decrease in PTSD symptoms over the course of the trial.

CONCLUSIONS

PTSD subjects with low BDNF levels demonstrated the largest treatment response from an agent with putative neurotrophic effects.

Association among basal serum BDNF, cardiorespiratory fitness and cardiovascular disease risk factors in untrained healthy Korean men

Evidence suggests that serum brain-derived neurotrophic factor (serum BDNF) can be affected by cardiorespiratory fitness (CRF), but this relationship is far from clear. Recent reports show an inverse relationship between serum BDNF and CRF in healthy individuals, and other studies suggest a possible association between serum BDNF and cardiovascular disease. However, the possible interaction between serum BDNF, CRF, and cardiovascular disease risk has not been studied. The purpose of this study was to examine the association among serum BDNF, CRF, and cardiovascular disease risk factors in healthy men. The investigation involved a large sample of men (n = 995, age range: 20-76 years) who live in the central area of South Korea and were recruited into the Preventive Health Study. Our study showed a significant inverse relationship between serum BDNF and relative VO(2)max (r = -0.412, p < 0.0001) and heart rate reserve (r = -0.194, p < 0.0001). Serum BDNF was positively correlated with body mass index (r = 0.80, p < 0.0001), total cholesterol (r = 0.185, p < 0.0001), and triglyceride (r = 0.320, p < 0.0001). Our data suggest that serum BDNF may be associated with effects of increased CRF on cardiovascular disease. However, more research is clearly needed before a determination of whether, and to what extent, serum BDNF may be responsible for some of the health benefits associated with CRF.

Does a period of detraining cause a decrease in serum brain-derived neurotrophic factor?

Brain-derived neurotrophic factor (BDNF) is one of the neurotrophins promoting cognitive function and contributing to neurogenesis and neuroprotection. Available evidence suggests that exercise influences serum BDNF concentrations, but that the effect is transient. The purpose of this study is to determine whether a period of aerobic training, followed by a period of detraining, can influence basal serum BDNF levels in humans. Sixteen young, sedentary subjects were assigned to an experimental group (n=9) and a control group (n=7). The experimental group performed an aerobic training program during 8 weeks, followed by 8 weeks of detraining, during which subjects returned to their previous, sedentary activity level. The control group remained physically inactive during 16 weeks. In both groups, performance on short-term (Digit Span test) and mid-term memory (Recall of Images) was assessed. Aerobic training significantly increased the VO(2) peak in the experimental group, and these values returned to baseline after 8 weeks of detraining. Basal serum BDNF was not influenced by 8 weeks of aerobic training and detraining did not seem to have an effect on basal peripheral BDNF concentrations. Both training and detraining did not clearly influence short-term memory performance on the Digit Span test and no differences were present between the experimental and control group on the mid-term memory test. Future studies should focus on patient groups and elderly to further investigate the effect of training and detraining on neurotrophic factors and cognitive function, and on the effects of training and detraining on the BDNF response to acute exercise.

Exercising during learning improves vocabulary acquisition: behavioral and ERP evidence

Numerous studies have provided evidence that physical activity promotes cortical plasticity in the adult brain and in turn facilitates learning. However, until now, the effect of simultaneous physical activity (e.g. bicycling) on learning performance has not been investigated systematically. The current study aims at clarifying whether simultaneous motor activity influences verbal learning compared to learning in a physically passive situation. Therefore the learning behavior of 12 healthy subjects (4 male, 19-33 years) was monitored over a period of 3 weeks. During that time, behavioral and electrophysiological responses to memorized materials were measured. We found a larger N400 effect and better performance in vocabulary tests when subjects were physically active during the encoding phase. Thus, our data indicate that simultaneous physical activity during vocabulary learning facilitates memorization of new items.

Endogenous reward mechanisms and their importance in stress reduction, exercise and the brain

Stress can facilitate disease processes and causes strain on the health care budgets. It is responsible or involved in many human ailments of our time, such as cardiovascular illnesses, particularly related to the psychosocial stressors of daily life, including work. Besides pharmacological or clinical medical treatment options, behavioral stress reduction is much-needed. These latter approaches rely on an endogenous healing potential via life-style modification. Hence, research has suggested different ways and approaches to self-treat stress or buffer against stressors and their impacts. These self-care-centred approaches are sometimes referred to as mind-body medicine or multi-factorial stress management strategies. They consist of various cognitive behavioral techniques, as well as relaxation exercises and nutritional counselling. However, a critical and consistent element of modern effective stress reduction strategies are exercise practices. With regard to underlying neurobiological mechanisms of stress relief, reward and motivation circuitries that are imbedded in the limbic regions of the brain are responsible for the autoregulatory and endogenous processing of stress. Exercise techniques clearly have an impact upon these systems. Thereby, physical activities have a potential to increase mood, i.e., decrease psychological distress by pleasure induction. For doing so, neurobiological signalling molecules such as endogenous morphine and coupled nitric oxide pathways get activated and finely tuned. Evolutionarily, the various activities and autoregulatory pathways are linked together, which can also be demonstrated by the fact that dopamine is endogenously converted into morphine which itself leads to enhanced nitric oxide release by activation of constitutive nitric oxide synthase enzymes. These molecules and mechanisms are clearly stress-reducing.

High-intensity extended swimming exercise reduces pain-related behavior in mice: involvement of endogenous opioids and the serotonergic system

The present study examined the hyponociceptive effect of swimming exercise in a chemical behavioral model of nociception and the mechanisms involved in this effect. Male mice were submitted to swimming sessions (30 min/d for 5 days). Twenty-four hours after the last session, we noticed that swimming exercise decreased the number of abdominal constriction responses caused by acetic acid compared with the nonexercised group. The hyponociception caused by exercise in the acetic acid test was significantly attenuated by intraperitoneal (i.p.) pretreatment of mice with naloxone (a nonselective opioid receptor antagonist, 1 mg/kg), ρ-chlorophenylalanine methyl ester (PCPA, an inhibitor of serotonin synthesis, 100 mg/kg once a day for 4 consecutive days), and by bilateral adrenalectomy. Collectively, the present results provide experimental evidences indicating for the first time that high-intensity extended swimming exercise reduces pain-related behavior in mice. The mechanisms involve an interaction with opioid and serotonin systems. Furthermore, endogenous opioids released by adrenal glands probably are involved in this effect.

PERSPECTIVE

Our results indicate that high-intensity extended exercise endogenously controls acute pain by activation of opioidergic and serotonergic pathways. Furthermore, these results support the use of exercise as a nonpharmacological approach for the management of acute pain.

Acute exercise ameliorates reduced brain-derived neurotrophic factor in patients with panic disorder

The neurotrophin brain-derived neurotrophic factor (BDNF) has been implicated in depression and anxiety. Antidepressants and exercise increase BDNF expression, and both have an antidepressant and anxiolytic activity. To further characterize the association of anxiety, BDNF and exercise, we studied panic disorder patients (n=12) and individually matched healthy control subjects (n=12) in a standardized exercise paradigm. Serum samples for BDNF analyses were taken before and after 30min of exercise (70 VO(2max)) or quiet rest. The two conditions were separated by 1 week and the order was randomized. Non-parametric statistical analyses were performed. There was a negative correlation of BDNF concentrations and subjective arousal at baseline (r=-0.42, p=0.006). Compared to healthy control subjects, patients with panic disorder had significantly reduced BDNF concentrations at baseline and 30min of exercise significantly increased BDNF concentrations only in these patients. Our results suggest that acute exercise ameliorates reduced BDNF concentrations in panic disorder patients and raise the question whether this is also found after long-term exercise training and if it is related to the therapeutic outcome.

Acute strength exercise and the involvement of small or large muscle mass on plasma brain-derived neurotrophic factor levels

OBJECTIVE

Blood neurotrophins, such as the brain-derived neurotrophic factor, are considered to be of great importance in mediating the benefits of physical exercise. In this study, the effect of acute strength exercise and the involvement of small versus large muscle mass on the levels of plasma brain-derived neurotrophic factor were evaluated in healthy individuals.

METHODS

The concentric strengths of knee (large) and elbow (small) flexor and extensor muscles were measured on two separate days. Venous blood samples were obtained from 16 healthy subjects before and after exercise.

RESULTS

The levels of brain-derived neurotrophic factor in the plasma did not significantly increase after both arm and leg exercise. There was no significant difference in the plasma levels of the brain-derived neurotrophic factor in the arms and legs.

CONCLUSION

The present results demonstrate that acute strength exercise does not induce significant alterations in the levels of brain-derived neurotrophic factor plasma concentrations in healthy individuals. Considering that its levels may be affected by various factors, such as exercise, these findings suggest that the type of exercise program may be a decisive factor in altering peripheral brain-derived neurotrophic factor.

The acute response of plasma brain-derived neurotrophic factor as a result of exercise in major depressive disorder

Brain-derived neurotrophic factor (BDNF) and other neurotrophins are believed to play an important role in affective disorders. In this study we investigated plasma-BDNF response during an incremental exercise test in 18 patients suffering from moderate major depressive disorder (MDD) and 18 controls. The patients were not treated with antidepressants or neuroleptics. Possible associations between plasma plasma-BDNF levels, dexamethasone suppression test cortisol levels and Montgomery-Asberg Depression Rating Scale (MADRS) scores were also tested. No difference in basal BDNF levels between patients and controls was found. BDNF increased significantly during exercise in both male and female patients as well as in male controls, with no significant differences between the groups. BDNF levels declined after exercise, but after 60 min of rest BDNF levels showed tendencies to increase again in male patients. No correlation between BDNF and cortisol or MADRS scores was found. We conclude that unmedicated patients with moderate depression and normal activity of the hypothalamic-pituitary-adrenal axis do not have a disturbed peripheral BDNF release during exercise. The BDNF increase 60 min after interruption of exercise in male patients might indicate up-regulated BDNF synthesis, but this needs to be further investigated in future studies.

Evidence for a release of brain-derived neurotrophic factor from the brain during exercise

Brain-derived neurotrophic factor (BDNF) has an important role in regulating maintenance, growth and survival of neurons. However, the main source of circulating BDNF in response to exercise is unknown. To identify whether the brain is a source of BDNF during exercise, eight volunteers rowed for 4 h while simultaneous blood samples were obtained from the radial artery and the internal jugular vein. To further identify putative cerebral region(s) responsible for BDNF release, mouse brains were dissected and analysed for BDNF mRNA expression following treadmill exercise. In humans, a BDNF release from the brain was observed at rest (P < 0.05), and increased two- to threefold during exercise (P < 0.05). Both at rest and during exercise, the brain contributed 70-80% of circulating BDNF, while that contribution decreased following 1 h of recovery. In mice, exercise induced a three- to fivefold increase in BDNF mRNA expression in the hippocampus and cortex, peaking 2 h after the termination of exercise. These results suggest that the brain is a major but not the sole contributor to circulating BDNF. Moreover, the importance of the cortex and hippocampus as a source for plasma BDNF becomes even more prominent in response to exercise.

Brain-derived neurotrophic factor is produced by skeletal muscle cells in response to contraction and enhances fat oxidation via activation of AMP-activated protein kinase

AIMS/HYPOTHESIS

Brain-derived neurotrophic factor (BDNF) is produced in skeletal muscle, but its functional significance is unknown. We aimed to determine the signalling processes and metabolic actions of BDNF.

METHODS

We first examined whether exercise induced BDNF expression in humans. Next, C2C12 skeletal muscle cells were electrically stimulated to mimic contraction. L6 myotubes and isolated rat extensor digitorum longus muscles were treated with BDNF and phosphorylation of the proteins AMP-activated protein kinase (AMPK) (Thr(172)) and acetyl coenzyme A carboxylase beta (ACCbeta) (Ser(79)) were analysed, as was fatty acid oxidation (FAO). Finally, we electroporated a Bdnf vector into the tibialis cranialis muscle of mice.

RESULTS

BDNF mRNA and protein expression were increased in human skeletal muscle after exercise, but muscle-derived BDNF appeared not to be released into the circulation. Bdnf mRNA and protein expression was increased in muscle cells that were electrically stimulated. BDNF increased phosphorylation of AMPK and ACCbeta and enhanced FAO both in vitro and ex vivo. The effect of BDNF on FAO was AMPK-dependent, since the increase in FAO was abrogated in cells infected with an AMPK dominant negative adenovirus or treated with Compound C, an inhibitor of AMPK. Electroporation of a Bdnf expression vector into the tibialis cranialis muscle resulted in increased BDNF protein production and tropomyosin-related kinase B (TrkB(Tyr706/707)) and extracellular signal-regulated protein kinase (p44/42 Thr(202)/Tyr(204)) phosphorylation in these muscles. In addition, phosphorylation of ACCbeta was markedly elevated in the Bdnf electroporated muscles.

CONCLUSIONS/INTERPRETATION

These data identify BDNF as a contraction-inducible protein in skeletal muscle that is capable of enhancing lipid oxidation in skeletal muscle via activation of AMPK.

Plasma BDNF is reduced among middle-aged and elderly women with impaired insulin function: evidence of a compensatory mechanism

Brain-derived neurotrophic factor (BDNF) plays a regulatory role in neuronal differentiation and synaptic plasticity and has been linked to glucose regulation and cognition. Associations among plasma BDNF, cognition, and insulin function were explored. Forty-one participants with impaired insulin function (IIF), ranging from insulin resistance to type 2 diabetes mellitus (T2DM), were matched with 41 healthy controls on gender, age, education, and IQ. Participants received complete medical, neurological, psychiatric, and neuropsychological evaluations. IIF individuals had significantly lower plasma BDNF levels than controls, particularly females, and higher BDNF levels were associated with poorer explicit memory in IIF females, suggesting that higher levels within this group may reflect the body's efforts to respond to damage. After accounting for age, education, and HbA1c, BDNF significantly predicted 13.1-23.5% of the variance in explicit memory in IIF women. These findings suggest that BDNF elevations within diseased groups may not always be a marker of health.

Brain-derived neurotrophic factor in infants <32 weeks gestational age: correlation with antenatal factors and postnatal outcomes

Neurotrophins (NTs) play important roles in brain growth and development. Cord blood (CB) brain-derived neurotrophic factor (BDNF) concentrations increase with gestational age but data regarding postnatal changes are limited. We measured BDNF concentrations after birth in 33 preterm infants <32-wk gestation. Serum was collected at birth (CB), at day 2, between day 6 and 10 (D6), at day 30 (D30), and at day 60 (D60). BDNF concentrations fell on D2 (p = 0.03), recovered by D6 (p = 0.10), and continued to rise thereafter at D30 (p = 0.06) and D60 (p = 0.01) compared with CB. CB BDNF concentrations positively correlated with duration of rupture of membranes (r = 0.43, p = 0.04). Antenatal steroids (ANS, p = 0.02), postnatal steroids (PNS, p = 0.04), and retinopathy of prematurity (ROP, p = 0.02) were identified as significant factors in multivariate analyses. The median (25-75th interquartile range) CB BDNF concentrations were higher in infants who received a complete course ANS compared with those who received a partial course [1461 (553-2064) versus 281 (171-536) pg/mL, p = 0.04]. BDNF concentrations negatively correlated with the use of PNS at D30 (r = -0.53, p = 0.002) and at D60 (r = -0.55, p = 0.009). PNS use was associated with reduced concentrations of BDNF at D30 [733 (101-1983) versus 2224 (1677- 4400) pg/mL, p = 0.004] and at D60 [1149 (288-2270) versus 2560 (1337-5166) pg/mL, p = 0.01]. BDNF concentrations on D60 in infants who developed ROP (n = 16) were lower than those who did not develop ROP (n = 7) [1417 (553-2540) versus 3593 (2620-7433) pg/mL, respectively, p = 0.005]. Our data suggests that BDNF concentrations rise beyond the first week of age. BDNF concentrations correlate with factors that influence neurodevelopment outcomes.

Preliminary evidence of cannabinoid effects on brain-derived neurotrophic factor (BDNF) levels in humans

BACKGROUND

Acute and chronic exposure to cannabinoids has been associated with cognitive deficits, a higher risk for schizophrenia and other drug abuse. However, the precise mechanism underlying such effects is not known. Preclinical studies suggest that cannabinoids modulate brain-derived neurotrophic factor (BDNF). Accordingly, we hypothesized that Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the principal active component of cannabis, would alter BDNF levels in humans.

MATERIALS AND METHODS

Healthy control subjects (n = 14) and light users of cannabis (n = 9) received intravenous administration of (0.0286 mg/kg) Delta(9)-THC in a double-blind, fixed order, placebo-controlled, laboratory study. Serum sampled at baseline, after placebo administration, and after Delta(9)-THC administration was assayed for BDNF using ELISA.

RESULTS

Delta(9)-THC increased serum BDNF levels in healthy controls but not light users of cannabis. Further, light users of cannabis had lower basal BDNF levels. Delta(9)-THC produced psychotomimetic effects, perceptual alterations, and "high" and spatial memory impairments.

IMPLICATIONS

The effects of socially relevant doses of cannabinoids on BDNF suggest a possible mechanism underlying the consequences of exposure to cannabis. This may be of particular importance for the developing brain and also in disorders believed to involve altered neurodevelopment such as schizophrenia. Larger studies to investigate the effects of cannabinoids on BDNF and other neurotrophins are warranted.

Cardio-respiratory fitness, habitual physical activity and serum brain derived neurotrophic factor (BDNF) in men and women

Short episodes of high intensity exercise transiently increase serum levels of BDNF in humans, but serum levels of BDNF at rest appear to be lower in more physically active humans with greater levels of energy expenditure. The relationship between serum BDNF concentration, cardio-respiratory fitness (Astrand-Rhyming test estimated VO2 max) and volume of long-term, regular exercise and sporting activity (Baecke Habitual Physical Activity Index) was investigated in 44 men and women between the age range of 18-57 years. In this group an inverse relationship between resting serum BDNF concentration and measures of both estimated VO2 max (r=-0.352; P<0.05) and long-term sporting activity (r=-0.428, P<0.01) was found. These results indicate that increased levels of cardio-respiratory fitness and habitual exercise are associated with lower resting levels of serum BDNF in healthy humans. This is the first study to demonstrate an inverse relationship between a physiological estimate of cardio-respiratory fitness and serum BDNF.

Transcriptional control of complement activation in an exercise model of chronic fatigue syndrome

Complement activation resulting in significant increases of C4a split product may be a marker of postexertional malaise in individuals with chronic fatigue syndrome (CFS). This study focused on identification of the transcriptional control that may contribute to the increased C4a in CFS subjects after exercise. We used quantitative reverse-transcription polymerase chain reaction to evaluate differential expression of genes in the classical and lectin pathways in peripheral blood mononuclear cells (PBMCs). Calibrated expression values were normalized to the internal reference gene peptidylpropyl isomerase B (PPIB), the external reference gene ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL), or the geometric mean (GM) of the genes ribosomal protein, large, P0 (RPLP0) and phosphoglycerate kinase 1 (PGK1). All nine genes tested, except mannose-binding lectin 2 (MBL2), were expressed in PBMCs. At 1 hour postexercise, C4, mannan-binding lectin serine protease 2 (MASP2) and ficolin 1 (FCN1) transcripts were detected at higher levels (> or = 2-fold) in at least 50% (4 of 8) of CFS subjects and were detected in 88% (7 of 8) CFS subjects when subjects with overexpression of either C4 or MASP2 were combined. Only an increase in the MASP2 transcript was statistically significant (PPIB, P = 0.001; GM, P = 0.047; rbcL, P = 0.045). This result may be due to the significant but transient downregulation of MASP2 in control subjects (PPIB, P = 0.023; rbcL, P = 0.027). By 6 hours postexercise, MASP2 expression was similar in both groups. In conclusion, lectin pathway responded to exercise differentially in CFS than in control subjects. MASP2 down-regulation may act as an antiinflammatory acute-phase response in healthy subjects, whereas its elevated level may account for increased C4a and inflammation-mediated postexertional malaise in CFS subjects.

Sex differences in skilled movement in response to restraint stress and recovery from stress

Sex differences exist in skilled movement, and skilled motor performance is also influenced by stress. As shown for cognitive function, the effects of stress are usually characterized by considerable sexual dimorphism. The purpose of this study was to investigate sex differences in skilled motor function in response to stress. Male and female Long-Evans rats were trained and tested in skilled reaching and skilled walking tasks. Both groups of animals were then exposed to daily restraint stress for 15 days. Recovery from daily stress was assessed by comparing reaching performance at 10 min versus 60 min after restraint stress, and recovery from chronic stress was tested for 21 days after cessation of stress. Animals were tested daily in skilled reaching for the entire period. Observations showed that females performed significantly better than males during the stress period in terms of reaching success and number of attempts needed to grasp a food pellet. No difference between testing at 10 or 60 min after daily stress was found. Analysis of movement patterns and recovery from stress indicated that males and females use different strategies to overcome stress-induced motor disturbance. While male rats preferred to use original movement patterns, females tended to modify these patterns in order to increase reaching success. Modification of movement patterns in female rats was accompanied by a faster recovery in success rate after the cessation of stress. These results indicate sex differences in skilled reaching in response to stress, and in the recovery period after stress.

Centrifugal acceleration to 3Gz is related to increased release of stress hormones and decreased mood in men and women

It has been suggested that the central and peripheral neural processes (CPNP) are affected by gravitational changes. Based on the previous experiments during parabolic flights, central and peripheral changes may not only be due to the changed gravitational forces but also due to neuroendocrine reactions related to the psycho-physiological consequences of gravitational changes. The present study focuses on the interaction of neuroendocrine changes and the physical and mental states after acceleration to three-time terrestrial gravity (3Gz). Eleven participants (29.4+/-5.1 [SD] years (male (n=8): 30+/-5.1 years; female (n=3): 27.7+/-2.1 years) underwent a 15 min acceleration to 3Gz in a human centrifuge. Before and after the acceleration to 3Gz circulating stress hormone concentrations (cortisol, adrenocorticotropic hormone (ACTH), prolactin, epinephrine, norepinephrine) and perceived physical and mental states were recorded. A second control group of 11 participants underwent the same testing procedure in a laboratory session. Serum cortisol concentration during exposure to the centrifugal acceleration increased by 70%, plasma concentration of ACTH increased threefold, prolactin twofold, epinephrine by 70% and norepinephrine by 45%, whereas the perceived physical well-being decreased. These findings demonstrate that psycho-physiological changes have to be regarded as a relevant factor for the changes in CPNP during phases of hypergravity exposure.

Drugs in sport: a scientist-athlete's perspective: from ambition to neurochemistry

This article, by the United Kingdom's last Olympic Marathon Medal winner, Charlie Spedding, and his brother, the pharmacologist, Michael Spedding, covers the difficulties posed by the availability of powerful drugs to ameliorate athletic performance, from an athlete's perspective, particularly in view of the fact that performances are becoming highly optimised with less margin for further physiological improvement. The authors have had long athletic careers and argue that doping not only devalues performance but sport, and exercise, as a whole. Furthermore, the neurotrophic and metabolic changes involved in exercise and training, which can be modified by drugs, are central to health and reflect a part of the epidemic in obesity.

Impact of exercise on neuroplasticity-related proteins in spinal cord injured humans

The present study investigated the effects of exercise on the serum concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), prolactin (PRL) and cortisol (COR) in 11 chronically spinal cord-injured athletes. In these subjects BDNF concentration at rest was sixfold higher compared with the concentrations reported earlier in able-bodied persons, while IGF-1, PRL and COR were within normal range. Ten minutes of moderate intensity handbiking (54% of the maximal heart rate) during a warm-up period (W) induced an increase (P<0.05) of BDNF of approximately 1.5-fold from basal level at rest, while a decrease to basal level was found after an immediately succeeding handbiking time trial (89% of the maximal heart rate) over the marathon distance of 42 km (M). An increase (P<0.01) of serum IGF-1 was found after W and this levels remained elevated (P<0.01) until the end of M. W had no significant effects on the serum PRL and COR, however, M induced an increase (P<0.01) of both hormones. This is the first study showing elevated BDNF concentrations at rest in spinal cord-injured athletes. Furthermore, short moderate intensity handbiking but not immediately following long lasting high intensity handbiking further increases serum BDNF concentrations. IGF-1 response to exercise differs to BDNF response as this neuroplasticity-related protein remains elevated during the long lasting physical demand with high intensity. The augmented PRL concentration suggests that a possible mechanism by which exercise promotes neuroplasticity might be the activation of neural serotonergic pathways as 5-HT is the main PRL releasing factor. Elevated COR concentrations after M are unlikely to be deleterious to neuroplasticity as COR concentrations remain within the physiological range. The present study suggests that exercise might be beneficial to enhance neuroprotection and neuroplasticity, thereby improving recovery after spinal cord injury.

Influence of exercise on serum brain-derived neurotrophic factor concentrations in healthy human subjects

The effect of short-term exercise (15 min step-exercise) on serum brain-derived neurotrophic factor (BDNF) levels was evaluated in healthy human subjects. Results showed a short-term, significant increase in serum BDNF levels after exercise. Intra-individual differences in serum BDNF levels were remarkably small on the rest day and also when compared to rest values on the day of the exercise test. Inter-individual differences, on the other hand, were larger by comparison. The result of this study supports the need for larger sample size in studies on BDNF changes in psychiatric disorders or psychiatric drug effects.

Capitalizing on cortical plasticity: influence of physical activity on cognition and brain function

Given the aging populations in many countries throughout the world, there is an increasing interest in lifestyle factors and interventions that will enhance the cognitive vitality of older adults and reduce the risk for age-related neurological disorders, such as Alzheimer's disease. In this review, we evaluate the hypothesis that physical activity and exercise might serve to protect, and also enhance, cognitive and brain function across the adult lifespan. To this end, we critically review three separate literatures that have examined the influence of physical activity and exercise on cognition, brain function and brain structure of adults, including epidemiological or prospective observational studies, randomized human clinical interventions and non-human animal studies. We suggest that this literature supports the claim that physical activity enhances cognitive and brain function, and protects against the development of neurodegenerative diseases. We discuss future directions to address currently unresolved questions, such as interactions between multiple lifestyle factors on offsetting or protecting against cognitive and neural decline, and conclude that physical activity is an inexpensive treatment that could have substantial preventative and restorative properties for cognitive and brain function.