Physical exercise and cognition in older adults, a scientific approach scanty reported in Latin America and Caribbean populations.

The advancement of public services, including the increased accessibility of health services, has led to a rise in life expectancy globally. As a result, aging populations are becoming more prevalent, raising concerns about cognitive decline. Fortunately, non-pharmacological methods, such as physical exercise, have been shown to mitigate the effects of aging on the brain. In this perspective article, we examined meta-analyses on the impact of physical exercise on cognition in older adults. The results indicate that combined exercise (i.e., aerobic plus strength training), has a significant positive effect on overall cognition and executive function. However, we found a lack of scientific studies on this topic in Latin American and Caribbean countries. Therefore, there is a pressing need for research to identify the feasibility of physical exercise interventions to improve cognitive skills in older adults from these regions.

Impact of Breaking up of Sitting Time on Anti-inflammatory Response Induced by Extracellular Vesicles.

Physical inactivity and sedentary behaviors (SB) have promoted a dramatic increase in the incidence of a host of chronic disorders over the last century. The breaking up of sitting time (i.e., sitting to standing up transition) has been proposed as a promising solution in several epidemiological and clinical studies. In parallel to the large interest it initially created, there is a growing body of evidence indicating that breaking up prolonged sedentary time (i.e., > 7 h in sitting time) could reduce overall mortality risks by normalizing the inflammatory profile and cardiometabolic functions. Recent advances suggest that the latter health benefits, may be mediated through the immunomodulatory properties of extracellular vesicles. Primarily composed of miRNA, lipids, mRNA and proteins, these vesicles would influence metabolism and immune system functions by promoting M1 to M2 macrophage polarization (i.e., from a pro-inflammatory to anti-inflammatory phenotype) and improving endothelial function. The outcomes of interrupting prolonged sitting time may be attributed to molecular mechanisms induced by circulating angiogenic cells. Functionally, circulating angiogenic cells contribute to repair and remodel the vasculature. This effect is proposed to be mediated through the secretion of paracrine factors. The present review article intends to clarify the beneficial contributions of breaking up sitting time on extracellular vesicles formation and macrophage polarization (M1 and M2 phenotypes). Hence, it will highlight key mechanistic information regarding how breaking up sitting time protocols improves endothelial health by promoting antioxidant and anti-inflammatory responses in human organs and tissues.

Remote, Whole-Body Interval Training Improves Muscular Endurance and Cardiac Autonomic Control in Young Adults.

High-intensity interval training (HIIT) is an exercise modality acknowledged to maintain physical fitness with more engagement in an active lifestyle compared with other traditional exercise models. Nevertheless, its effects on cardiac control and physical performance in an online-guided setting are not yet clarified. The present work assessed physical fitness and heart rate variability (HRV) before and after an online, home-based HIIT program in college-age students while pandemic lockdowns were in effect. Twenty university students (age: 21.9 ± 2.4 years.) that were solely enrolled in online classes were distributed into three groups: control-CON-(n = 6), 14 min of HIIT-HIIT-14-(n = 8), and 21 min of HIIT-HIIT-21-(n = 6). A maximal push-up test was employed to assess muscular endurance and performance, and resting HRV signals were collected with wireless heart rate monitors and were processed in Kubios HRV Std. (Kubios Oy, Finland). There was an increase in total push-up capacity compared to CON (p < 0.05 HIIT-21 vs. CON; p < 0.001 HIIT-14 vs. CON) after 8 weeks. A significant interaction was observed in high-frequency and low-frequency spectra ratios after the HIIT-21 intervention (p < 0.05). The current work demonstrated that either short- or mid-volume online, whole-body HIIT improves muscle strength, whereas mid-volume HIIT (HIIT-21) was the only intervention that developed a sympathovagal adaptation. This study showed promising results on muscular endurance and cardiac autonomic modulation through whole-body HIIT practice at home.

Short-Term High-Intensity Circuit Training Does Not Modify Resting Heart Rate Variability in Adults during the COVID-19 Confinement.

BACKGROUND/OBJECTIVE: The quarantine caused by the COVID-19 pandemic increased sedentary behavior, psychological stress, and sleep disturbances in the population favoring the installation of alterations in the cardiovascular system. In this sense, physical exercise has widely been suggested as an efficient treatment to improve health. The current study determined the impact of short-term high-intensity circuit training (HICT) on resting heart rate variability (HRV) in adults. METHODS: Nine healthy participants (age: 31.9 ± 4.4 yr.) performed 36 HICT sessions (3 times per day; 3 days per week) and four participants (age: 29.5 ± 1.7 yr.) were assigned to a control group. The HICT consisted of 12 min of whole-body exercises performed during a workout. Twenty-four hours before and after the exercise program, HRV parameters were recorded. RESULTS: The heart rate exercise during the last session trended to be lower when compared with the first HICT session (p = 0.07, d = 0.39, 95% CI = -13.50, 0.72). The interval training did not modify the HRV time (Mean NN, SDNN, RMSSD, NN50, pNN50) and frequency (LF, HF, LF/HF ratio, total power) domain parameters. CONCLUSION: Thirty-six HICT sessions did not provide enough stimuli to modify the resting HRV in adults during social isolation elicited by the COVID-19 pandemic. However, the data suggested that exercise protocol did not induce cardio-vagal adaptations.

Unhealthy Dieting During the COVID-19 Pandemic: An Opinion Regarding the Harmful Effects on Brain Health.

Since 2020, the world has been suffering from a pandemic that has affected thousands of people regardless of socio-economic conditions, forcing the population to adopt different strategies to prevent and control the advance of the disease, one of which is social distancing. Even though social distancing is a safe strategy to reduce the spread of COVID-19, it is also the cause of a rising sedentary behavior. This behavior develops an excess of fat tissue that leads to metabolic and inflammatory disruption related to chronic diseases and mental health disorders, such as anxiety, depression, and sleep issues. Furthermore, the adoption of dietary patterns involving the consumption of ultra-processed foods, higher in fats and sugars, and the reduction of fresh and healthy foods may play a role in the progress of the disease. In this perspective, we will discuss how an unhealthy diet can affect brain function and, consequently, be a risk factor for mental health diseases.

Concurrent Training Increases Serum Brain-Derived Neurotrophic Factor in Older Adults Regardless of the Exercise Frequency.

Background: Human brain function declines with aging. In this sense, exercise-based interventions has a promising effect on brain plasticity for older adults. Serum brain-derived neurotrophic factor (BDNF) is a positive biomarker for brain neuroplasticity in healthy older adults also modified by exercise training. Selected features of the exercise prescription for improving brain health are missing; therefore, the aim of this study was to determine the effects of concurrent exercise training frequency on serum BDNF levels in healthy older adults. Methods: Nineteen volunteers (age: 65 ± 4 year; body mass index: 28.0 ± 4.5 kg/m2) completed either a three times/week (3-t/w) (n = 8) or five times/week (5-t/w) (n = 11) concurrent exercise program. The exercise program lasted 11 weeks and all exercise sessions were performed for 50 min at moderate intensity. Serum BDNF, body composition, cardiovascular, and physical fitness variables were assessed before and after the exercise training program. Results: Regardless of the group, the serum BDNF increased following the intervention (p < 0.001), and there were no significant group (p = 0.827) or interaction (p = 0.063) effects. The maximal oxygen consumption (VO2max) increased regardless of the group (p = 0.007), with a non-significant group (p = 0.722) or interaction (p = 0.223) effects. Upper- and lower-body strength increased in both groups (p = 0.003); however, there was no effect of the training frequency (p = 0.53). For the skeletal muscle mass, there was a trend in the interaction effect (p = 0.053). Finally, the body fat percentage was unchanged. Conclusion: Eleven weeks of combined exercise training increased serum BDNF levels in healthy older adults, a response independent of the training frequency. The overall fitness level improved similarly in both exercise groups. These data reveal that a minimal dosage of concurrent exercise enhance functional capacity and a brain health biomarker in older adults.

Menstrual cycle impacts adipokine and lipoprotein responses to acute high-intensity intermittent exercise bout.

Due to hormonal fluctuation, the menstrual cycle impacts inflammatory response and lipid metabolism; moreover, the anti-atherogenic and anti-inflammatory effects of exercise in this cycle, mainly high-intensity intermittent exercise (HIIE), need to be examined. Therefore, the aim of the current study was to investigate the influence of menstrual cycle phases on adipokine and lipoprotein responses after acute HIIE sessions in healthy women. Fourteen women (age: 24 ± 2 years; BMI: 22.79 ± 1.89 kg·m2) were recruited to perform two HIIE sessions (10 × 1 min running at 90% of maximum aerobic velocity, with 1 min recovery); one during the follicular phase (FP) and other during the luteal phase (LP), randomly. Blood samples were collected at rest, immediately, and 60 min after HIIE sessions. Macrophage inflammatory protein-1α (MIP-1α), leptin, adiponectin, total cholesterol, triacylglycerol (TAG), HDL-c, and glucose concentrations were analyzed. At rest, higher MIP-1α concentrations were observed during the LP compared to FP (p = 0.017). Likewise, leptin (p = 0.050), LDL-c (p = 0.015), and non-HDL (p = 0.016) were statistically higher in the LP. In contrast, the adiponectin/leptin ratio was lower in the LP compared to the ratio found in the FP (p = 0.032). Immediately post-HIIE sessions, in both menstrual phases, higher TAG (p = 0.001) and HDL-c (p = 0.001) concentrations were found, which returned to resting levels after 60 min. In conclusion, adipokine and lipoprotein responses after a single HIIE session are regulated by the phase of the menstrual cycle, contributing to inflammatory conditions, and demonstrating the importance of considering the phases of the menstrual cycle for the periodization of physical training.

The effects of interval training on peripheral brain derived neurotrophic factor (BDNF) in young adults: a systematic review and meta-analysis.

The aim of the current meta-analysis was to determine the effects of acute and chronic interval training (IT) on serum and plasma BDNF concentrations in healthy young adults. A literature search was performed using six databases until February 2020. The TESTEX scale was used to assess the quality of studies. Effect sizes (ES) were computed and two-tailed α values < 0.05 and non-overlapping 95% confidence intervals (95% CI) were considered statistically significant. Heterogeneity, inconsistency (I2), and small-study effects using the Luis Furuya-Kanamori (LFK) index were examined. Fifteen studies (n = 277 participants, age = 24 ± 3 years) were included. The overall effects of IT on circulating BDNF concentrations were moderate and significant (ES = 0.62, 95% CI 0.00, 1.24, heterogeneous (p < 0.001), highly inconsistent (I2 = 90%), and with major asymmetry (LFK index = 2.76). The acute effect of IT on peripheral BDNF levels was large and significant (ES = 1.10, 95% CI 0.07, 2.14), heterogeneous (p < 0.001), highly inconsistent (I2 = 92%), and with major asymmetry (LFK index = 3.34). The chronic effect of IT on circulating BDNF was large and significant (ES = 0.93, 95% CI 0.40, 1.46), heterogeneous (p < 0.001), with moderate inconsistency (I2 = 70%), and minor asymmetry (LFK index = 1.21). Acute and chronic IT elicited a moderate increase in serum and plasma BDNF concentrations in a healthy young population.

Role of Neuronal Guidance Cues in the Pathophysiology of Obesity: A Peripheral and Central Overview.

Obesity is associated with an exacerbated synthesis and secretion of several molecules, which culminates in chronic low-grade inflammation and insulin resistance. Such conditions affect molecular and physiological responses of several organs and, if not resolved, predispose the obese patients to other diseases such as Type 2 diabetes, atherosclerosis, cancer, neural injuries, and cognitive impairments. A microenvironment with an excess of pro-inflammatory cytokines released by different cells, including immune and adipose cells lead to metabolic and non-metabolic diseases during obesity. In this context, the role of neuronal guidance cues named netrin, semaphorin and ephrin is novel. Specifically, the available literature indicates that besides their classic role as molecules that guide the axon to its target site, the neuronal guidance cues exhibit immunomodulatory functions from adipose tissue to the neural environment. In the current narrative review, we discuss the participation of the neuronal guidance cues on the physiology and pathophysiology of obesity. We also discuss the feedback loop of obesity on the netrin, semaphorin and ephrin functions that impair the structure and function of the brain. The integrative view of the neuronal guidance cues can be relevant in designing new treatments focus on attenuating metabolic and immune disorders in obese patients and reduce the risk of acquiring diseases such as Type 2 diabetes, atherosclerosis, cancer, and neural injuries.

Peripheral BDNF and psycho-behavioral aspects are positively modulated by high-intensity intermittent exercise and fitness in healthy women.

Acute high-intensity intermittent exercise (HIIE) induces the myokine secretion associated with neurogenesis, as well brain-derived neurotrophic factor (BDNF); however, it remains unknown how the menstrual phase influences this secretion after an acute exercise session. The current study aimed to investigate the effects of HIIE performed in luteal and follicular menstrual phases on BDNF, cognitive function, mood, and exercise enjoyment. Fourteen healthy women completed four experimental sessions, randomly. One graded exercise test (GXT) and one HIIE session (10 × 1-min runs 90% peak GXT velocity [1-min recovery]) were performed for each menstrual phase. Blood samples were collected at rest and immediately after efforts, and the profile of mood states questionnaire (POMS) and Stroop-task test were applied. During the HIIE, subjective scales were applied (feeling, felt arousal, rate of perceived exertion, and physical activity enjoyment). The main results showed that the serum BDNF presented no difference between menstrual phases (p = 0.870); however, HIIE increased BDNF concentration in both menstrual phases (p = 0.030). In addition, the magnitude of circulating BDNF variation (Δ%BDNF) and [Formula: see text] demonstrated an inverse relationship in the follicular phase (r = - 0.539, p = 0.046), whereas in the luteal phase, Δ%BDNF was negatively correlated with time test (r = - 0.684, p = 0.007) and RPE (r = - 0.726, p = 0.004) in GXT. No differences between menstrual phases were observed for POMS (p ≥ 0.05); however, HIIE attenuated tension (p < 0.01), depression (p < 0.01), and anger moods (p < 0.01), independently of menstrual phases. The subjective scales and Stroop-task test did not show differences. In conclusion, menstrual cycle phase does not affect serum BDNF levels, cognitive function, mood, and exercise enjoyment. Contrary, HIIE increases peripheral BDNF and attenuates tension, depression, and anger independently of menstrual phase. In addition, Δ%BDNF was correlated with physical fitness in the follicular phase, exhibiting higher changes in women with lower physical fitness status.

Acute Systemic Response Of BDNF, Lactate and Cortisol to Strenuous Exercise Modalities in Healthy Untrained Women.

Acute bouts of intense exercise increase lactate concentration, which in turn stimulates brain-derived neurotrophic factor (BDNF) production. Cortisol released during intense exercise might inhibit BDNF synthesis. This study examined the acute effects of 2 protocols of strenuous exercise on serum BDNF. Seventeen physically-active healthy females (Age = 20.0 ± 0.9 yr., BMI = 23.0 ± 2.6 kg/m2) performed a strenuous cycle-ergometer graded exercise test (GXT) and a high-intensity interval training session (HIIT). Serum BDNF, serum cortisol, cortisol: BDNF ratio and blood lactate (BLa) were recorded at baseline and immediately following exercise. Although non-statistically significant, the HIIT session elicited a higher magnitude of change from baseline for BDNF (d = 0.17) and cortisol (d = 1.18) than after the GXT (d = -0.26, and d = 0.82, respectively). An interaction was found between GXT and HIIT trials and measurements on BLa levels, with higher post-exertion values after HIIT than after GXT (p < 0.0001, η2 = 0.650, 95%CI = 2.2, 5.2). The higher BLa levels did not raise circulating BDNF. The elevated cortisol levels may have overcome the effects of lactate on BDNF. However, the higher BLa induced by HIIT suggest that interval exercise modality on the long-term could be a feasible intervention to increase circulating peripheral BDNF, at least in untrained healthy women.

Hemodynamic Adaptations Induced by Short-Term Run Interval Training in College Students.

Perceived lack of time is one of the most often cited barriers to exercise participation. High intensity interval training has become a popular training modality that incorporates intervals of maximal and low-intensity exercise with a time commitment usually shorter than 30 min. The purpose of this study was to examine the effects of short-term run interval training (RIT) on body composition (BC) and cardiorespiratory responses in undergraduate college students. Nineteen males (21.5 ± 1.6 years) were randomly assigned to a non-exercise control (CON, n = 10) or RIT (n = 9). Baseline measurements of systolic and diastolic blood pressure, resting heart rate (HRrest), double product (DP) and BC were obtained from both groups. VO2max and running speed associated with VO2peak (sVO2peak) were then measured. RIT consisted of three running treadmill sessions per week over 4 weeks (intervals at 100% sVO2peak, recovery periods at 40% sVO2peak). There were no differences in post-training BC or VO2max between groups (p > 0.05). HRrest (p = 0.006) and DP (p ≤ 0.001) were lower in the RIT group compared to CON at completion of the study. RIT lowered HRrest and DP in the absence of appreciable BC and VO2max changes. Thereby, RIT could be an alternative model of training to diminish health-related risk factors in undergraduate college students.

Impact of high-intensity interval training and sprint interval training on peripheral markers of glycemic control in metabolic syndrome and type 2 diabetes.

Glycemic control is essential to reduce the risk of complications associated with metabolic syndrome (MetS) and type 2 diabetes (T2D). Aerobic and resistance exercise performed alone or in combination improve glycemic control in both conditions. However, perceived lack of time and commitment are considered principal barriers to performing exercise regularly. High intensity interval training (HIIT) and sprint interval training (SIT) can be performed in a fraction of the time required for continuous aerobic exercise. A substantial scientific evidence indicates that HIIT/SIT improve glycemic control to a similar or greater extent than aerobic exercise in populations without MetS or T2D. Likewise, growing evidence suggest that HIIT/SIT improve the glycemic control during MetS and T2D. The aim of this review is to discuss the effects of interval training protocols on peripheral markers of glucose metabolism in patients with MetS and T2D.

Short-term high-Intensity interval training increases systemic brain-derived neurotrophic factor (BDNF) in healthy women.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) increases neuronal viability and cognitive function, peripheral lipid metabolism and skeletal muscle repair. The primary purpose of this study was to determine the effect of short-term high-intensity interval training (HIIT) on serum BDNF concentrations in healthy young women. METHODS: Seventeen women (age:22 ± 1 years); body mass index (BMI:24.2 ± 2.2 kg/m²), body fat percentage (% fat:25.8 ± 4.7) participated in the study. Participants were randomly assigned to a control (n = 8) or HIIT group (n = 9). All participants performed a graded exercise test (GXT) on an electronically-braked cycle ergometer to determine maximal aerobic power (MAP, Watts). HIIT was performed three days per week for four weeks. Each HIIT session consisted of three to five cycling bouts of 30 s each at 80% MAP, followed by four-minutes of recovery at 40% MAP. Forty-eight hours after the last bout of exercise, both groups performed a follow-up GXT. Non-fasting blood samples were collected before and immediately after each GXT. Mixed factorial (2 groups x 4 measures, and 2 groups x 2 measures) ANOVA was used to assess BDNF concentrations, performance and anthropometric variables. RESULTS: Serum BDNF concentrations in the HIIT group (21.9 ± 1.3 ng/mL) increased compared to control (19.2 ± 2.8 ng/mL) (∼12%, P < 0.05) following HIIT. In contrast, circulating BDNF concentrations were reduced following the GXT (P < 0.05). The MAP and % Fat did not change with HIIT. CONCLUSIONS: Twelve sessions of HIIT increases circulating BDNF concentrations in healthy young women despite no change in physical performance or % fat.

Moderate and high intensity chronic exercise reduces plasma tumor necrosis factor alpha and increases the Langerhans islet area in healthy rats.

OBJECTIVE: This study aimed to examine the effects of moderate (MIT) and high-intensity training (HIT) chronic exercise on plasma tumor necrosis factor alpha (TNF-α) level and its impact on Langerhans islet morphology in healthy rats. METHODS: Two-month old normal male Wistar rats were divided into three groups: control (C, n=6), MIT (n=6), and HIT (n=4). The training protocol consisted in 24 sessions of running on a treadmill at 60-80% maximal oxygen consumption (VO2max) for MIT, and >80% VO2max for HIT. TNF-α and insulin were measured with ELISA tests. Duodenal pancreas was dissected to analyze the Langerhans islets by immunohistochemistry, a correlation analysis was performed with the nuclei/total islet area. Results: HIT and MIT rats showed lower TNF-α plasma levels than controls. Plasma insulin level decreased significantly in HIT compared with C and MIT. In addition, the islet area and nuclei density per islet were higher in the exercise groups compared with C. However, none of the groups showed PD1 immunoreactivity. CONCLUSIONS: Under healthy conditions, the chronic exercise reduced plasmatic TNF-α level, and in the same sense, increased the size of the Langerhans islets, depending to the exercise intensity.

Effects of Moderate- and High-Intensity Chronic Exercise on the Adiponectin Levels in Slow-Twitch and Fast-Twitch Muscles in Rats.

Background and objectives: Adipose tissue and skeletal muscle secrete adiponectin, a hormone abundantly secreted by adipocytes, that through the adiponectin receptor, regulate glucose and lipid metabolism. Adiponectin appears to protect skeletal muscles from inflammatory damage induced by oxidative stress. It has been suggested that decreased adiponectin levels could be associated with pathologic conditions, including obesity and diabetes. Furthermore, some studies suggest that exercise could have a beneficial effect by increasing adiponectin levels, but this observation remains controversial. It is also unknown if physical exercise modifies adiponectin expression in skeletal muscles. The aim of this study was to investigate the effect of chronic exercise on serum adiponectin and adiponectin expression in slow-twitch (soleus) and fast-twitch (plantaris) muscles in healthy rats. Materials and methods: Two-month-old male Wistar rats were randomly divided into three groups with n = 6 in each group: control (C), moderate-intensity training (MIT), and high-intensity training (HIT). The rats were conditioned to run on a treadmill for the 8-week period. Forty-eight hours after the last session, blood samples were collected for adiponectin measurements and total RNA was isolated from plantaris and soleus muscles to measure by RT-qPCR adiponectin receptor 1 and adiponectin mRNA expression level. Results: MIT and HIT groups had reduced adiponectin protein levels in serum and the plantaris muscle, but not changes in adiponectin protein were observed in the soleus muscle. No significant differences in Adiponectin receptor 1 (AdipoR1) gene expression were observed following intense or moderate exercise in either muscle group studied. Conclusions: Our study shows that decreasing levels of circulating adiponectin is a result of physical exercise and should not be generalized as a predictive marker of disease.

The Impact of High-Intensity Interval Training on Brain Derived Neurotrophic Factor in Brain: A Mini-Review.

The brain-derived neurotrophic factor (BDNF) is a protein mainly synthetized in the neurons. Early evidence showed that BDNF participates in cognitive processes as measured at the hippocampus. This neurotrophin is as a reliable marker of brain function; moreover, recent studies have demonstrated that BDNF participates in physiological processes such as glucose homeostasis and lipid metabolism. The BDNF has been also studied using the exercise paradigm to determine its response to different exercise modalities; therefore, BDNF is considered a new member of the exercise-related molecules. The high-intensity interval training (HIIT) is an exercise protocol characterized by low work volume performed at a high intensity [i.e., ≥80% of maximal heart rate (HRmax)]. Recent evidence supports the contention that HIIT elicits higher fat oxidation in skeletal muscle than other forms of exercise. Similarly, HIIT is a good stimulus to increase maximal oxygen uptake (VO2max). Few studies have investigated the impact of HIIT on the BDNF response. The present work summarizes the effects of acute and long-term HIIT on BDNF.

Short-term fructose ingestion affects the brain independently from establishment of metabolic syndrome.

Chronic fructose ingestion is linked to the global epidemic of metabolic syndrome (MetS), and poses a serious threat to brain function. We asked whether a short period (one week) of fructose ingestion potentially insufficient to establish peripheral metabolic disorder could impact brain function. We report that the fructose treatment had no effect on liver/body weight ratio, weight gain, glucose tolerance and insulin sensitivity, was sufficient to reduce several aspects of hippocampal plasticity. Fructose consumption reduced the levels of the neuronal nuclear protein NeuN, Myelin Basic Protein, and the axonal growth-associated protein 43, concomitant with a decline in hippocampal weight. A reduction in peroxisome proliferator-activated receptor gamma coactivator-1 alpha and Cytochrome c oxidase subunit II by fructose treatment is indicative of mitochondrial dysfunction. Furthermore, the GLUT5 fructose transporter was increased in the hippocampus after fructose ingestion suggesting that fructose may facilitate its own transport to brain. Fructose elevated levels of ketohexokinase in the liver but did not affect SIRT1 levels, suggesting that fructose is metabolized in the liver, without severely affecting liver function commensurable to an absence of metabolic syndrome condition. These results advocate that a short period of fructose can influence brain plasticity without a major peripheral metabolic dysfunction.

Effect of moderate and high intensity chronic exercise on the pancreatic islet morphometry in healthy rats: BDNF receptor participation.

The function and morphology of ß-cells is largely dependent on insulin demand. As ß-cells cover a bigger cell proportion in pancreas islets, changes of insulin producer cells affect the whole pancreatic islet morphology. Growth factors as the neurotrophins regulate the pancreas physiology, besides; physical exercise increases insulin sensitivity, and further modifies brain derived neurotrophic factor (BDNF) concentration in plasma. The aim of this study was to investigate the effects of chronic exercise (running in a treadmill for 8 weeks) intensity on pancreatic islet morphometry in healthy state. The BDNF receptor effect on the pancreatic islet morphometry was also evaluated. Adult male Wistar rats were divided in 6 groups: Control (C); moderate intensity training (MIT); high intensity training (HIT) did not treat with BDNF receptor inhibitor (K252a), and C, MIT and HIT treated with K252a. The results shown that chronic exercise induces ß-cells hypertrophy without BDNF receptor participation. On the other hand, the moderate exercise increases the number of ß cells per islet; the last effect does not require TrkB participation. In sedentary conditions, the K252a treatment reduced the ß-cell density. Exercise intensity has differential effects on pancreas islet morphometry in healthy model; furthermore, BDNF receptor plays a role to maintain the amount of ß-cells in sedentary state.

Effects of moderate- and high-intensity chronic exercise on brain-derived neurotrophic factor expression in fast and slow muscles.

INTRODUCTION: Brain-derived neurotrophic factor (BDNF) protein expression is sensitive to cellular activity. In the sedentary state, BDNF expression is affected by the muscle phenotype. METHODS: Eighteen Wistar rats were divided into the following 3 groups: sedentary (S); moderate-intensity training (MIT); and high-intensity training (HIT). The training protocol lasted 8 weeks. Forty-eight hours after training, total RNA and protein levels in the soleus and plantaris muscles were obtained. RESULTS: In the plantaris, the BDNF protein level was lower in the HIT than in the S group (P < 0.05). A similar effect was found in the soleus (without significant difference). In the soleus, higher Bdnf mRNA levels were found in the HIT group (P < 0.001 vs. S and MIT groups). In the plantaris muscle, similar Bdnf mRNA levels were found in all groups. CONCLUSIONS: These results indicate that high-intensity chronic exercise reduces BDNF protein level in fast muscles and increases Bdnf mRNA levels in slow muscles.