Effects of physical training on hypothalamic neuronal activation and expressions of vasopressin and oxytocin in SHR after running until fatigue.

To assess the influence of physical training on neuronal activation and hypothalamic expression of vasopressin and oxytocin in spontaneously hypertensive rats (SHR), untrained and trained normotensive rats and SHR were submitted to running until fatigue while internal body and tail temperatures were recorded. Hypothalamic c-Fos expression was evaluated in thermoregulatory centers such as the median preoptic nucleus (MnPO), medial preoptic nucleus (mPOA), paraventricular nucleus of the hypothalamus (PVN), and supraoptic nucleus (SON). The PVN and the SON were also investigated for vasopressin and oxytocin expressions. Although exercise training improved the workload performed by the animals, it was reduced in SHR and followed by increased internal body temperature due to tail vasodilation deficit. Physical training enhanced c-Fos expression in the MnPO, mPOA, and PVN of both strains, and these responses were attenuated in SHR. Vasopressin immunoreactivity in the PVN was also increased by physical training to a lesser extent in SHR. The already-reduced oxytocin expression in the PVN of SHR was increased in response to physical training. Within the SON, neuronal activation and the expressions of vasopressin and oxytocin were reduced by hypertension and unaffected by physical training. The data indicate that physical training counterbalances in part the negative effect of hypertension on hypothalamic neuronal activation elicited by exercise, as well as on the expression of vasopressin and oxytocin. These hypertension features seem to negatively influence the workload performed by SHR due to the hyperthermia derived from the inability of physical training to improve heat dissipation through skin vasodilation.

Plant-based diets benefit aerobic performance and do not compromise strength/power performance: a systematic review and meta-analysis.

Plant-based diets have emerged as athletic performance enhancers for various types of exercise. Therefore, the present study evaluated the effectiveness of plant-based diets on aerobic and strength/power performances, as well as on BMI of physically active individuals. This systematic review and meta-analysis was conducted and reported according to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. A systematic search of electronic databases, including PubMed, Web of Science and SPORTDiscus, was performed. On the basis of the search and inclusion criteria, four and six studies evaluating the effects of plant-based diets on aerobic and strength/power performances in humans were, respectively, included in the systematic review and meta-analysis. Plant-based diets had a moderate but positive effect on aerobic performance (0·55; 95 % CI 0·29, 0·81) and no effect on strength/power performance (-0·30; 95 % CI -0·67, 0·07). The altogether analyses of both aerobic and strength/power exercises revealed that athletic performance was unchanged (0·01; 95 % CI -0·21, 0·22) in athletes who adopted plant-based diets. However, a small negative effect on BMI (-0·27; 95 % CI -0·40, -0·15) was induced by these diets. The results indicate that plant-based diets have the potential to exclusively assist aerobic performance. On the other hand, these diets do not jeopardise strength/power performance. Overall, the predicted effects of plant-based diets on physical performance are impactless, even though the BMI of their adherents is reduced.

Core body temperatures of rats subjected to treadmill exercise to fatigue or exhaustion: The journal Temperature toolbox.

This study systematically reviewed the literature reporting the changes in rats' core body temperature (TCORE) induced by either incremental- or constant-speed running to fatigue or exhaustion. In addition, multiple linear regression analyses were used to determine the factors contributing to the TCORE values attained when exercise was interrupted. Four databases (EMBASE, PubMed, SPORTDiscus, and Web of Science) were searched in October 2021, and this search was updated in August 2022. Seventy-two studies (n = 1,538 rats) were included in the systematic review. These studies described heterogeneous experimental conditions; for example, the ambient temperature ranged from 5 to 40°C. The rats quit exercising with TCORE values varying more than 8°C among studies, with the lowest and highest values corresponding to 34.9°C and 43.4°C, respectively. Multiple linear regression analyses indicated that the ambient temperature (p < 0.001), initial TCORE (p < 0.001), distance traveled (p < 0.001; only incremental exercises), and running speed and duration (p < 0.001; only constant exercises) contributed significantly to explaining the variance in the TCORE at the end of the exercise. In conclusion, rats subjected to treadmill running exhibit heterogeneous TCORE when fatigued or exhausted. Moreover, it is not possible to determine a narrow range of TCORE associated with exercise cessation in hyperthermic rats. Ambient temperature, initial TCORE, and physical performance-related variables are the best predictors of TCORE at fatigue or exhaustion. From a broader perspective, this systematic review provides relevant information for selecting appropriate methods in future studies designed to investigate exercise thermoregulation in rats.

TRPV1 inactivation alters core body temperature and serum corticosterone levels: Impacts on clock genes expression in the liver and adrenal glands.

PURPOSE: TRPV1 desensitization or blockade promotes hyperthermia in rodents. Daily changes in core body temperature (Tc), spontaneous locomotor activity (SLA), and glucocorticoids are temporal cues for peripheral clocks. Thus, this study aimed to evaluate the effects of both desensitization and blockade of TRPV1 on Tc, SLA, blood corticosterone, and the clock genes Per1 and Bmal1 in the liver and adrenal. METHODS AND RESULTS: Resiniferatoxin (RTX, 20 µg kg-1) known to desensitize the intra-abdominal TRPV1 channels was i. p. administered in adult male rats. One day after, RTX rats displayed higher Tc than vehicle rats (control) in the light and dark phases. RTX rats showed higher corticosterone at zeitgeber time (ZT) 6 and ZT12 compared to ZT0. Control rats showed a rise in corticosterone at ZT12. RTX abolished the Per1 peak in both the liver and adrenal glands, whereas it enhanced the peak of Bmal1 expression in the liver and decreased it in adrenal glands. Circadian variation in Tc and SLA was unaffected despite higher Tc being found along the light phase up to 5 days after RTX injection. Acute blockade of TRPV1 with the antagonist AMG-517 injected at ZT0 increased Tc and reduced corticosterone without affecting SLA. In the liver, while AMG-517 did not affect Per1, it increased Bmal1 mRNA. In adrenal glands, AMG-517 increased Per1 and did not affect Bmal1 expression. Although rats exposed to a 60-min 34 °C environment showed similar hyperthermia to that observed in AMG-517 rats, neither corticosterone nor liver nor adrenal clock genes changed. CONCLUSIONS: Inactivation of TRPV1 by abdominal desensitization or by antagonism alters the time-of-day changes of clock genes expression in the liver and adrenal, as well as corticosterone. TRPV1 may be necessary for signaling cyclical temporal cues for clock genes in the periphery but less critical for the circadian profile of Tc and SLA.

Predicting the body core temperature of recreational athletes at the end of a 10 km self-paced run under environmental heat stress.

NEW FINDINGS: What is the central question of this study? The aim was to identify the factors predicting the body core temperature of athletes at the end of a 10 km self-paced run in a hot environment. What is the main finding and its importance? Hyperthermia in athletes subjected to self-paced running depends on several factors, highlighting the integrated control of core temperature during exercise under environmental heat stress. Five of the seven variables that significantly predicted core temperature are not invasive and, therefore, practical for use outside the laboratory environment: heart rate, sweat rate, wet-bulb globe temperature, running speed and maximal oxygen consumption. ABSTRACT: Measurement of body core temperature (Tcore ) is paramount to determining the thermoregulatory strain of athletes. However, standard measurement procedures of Tcore are not practical for extended use outside the laboratory environment. Therefore, determining the factors that predict Tcore during a self-paced run is crucial for creating more effective strategies to minimize the heat-induced impairment of endurance performance and reduce the occurrence of exertional heatstroke. The aim of this study was to identify the factors predicting Tcore values attained at the end of a 10 km time trial (end-Tcore ) under environmental heat stress. Initially, we extracted data obtained from 75 recordings of recreationally trained men and women. Next, we ran hierarchical multiple linear regression analyses to understand the predictive power of the following variables: wet-bulb globe temperature, average running speed, initial Tcore , body mass, differences between Tcore and skin temperature (Tskin ), sweat rate, maximal oxygen uptake, heart rate and change in body mass. Our data indicated that Tcore increased continuously during exercise, attaining 39.6 ± 0.5°C (mean ± SD) after 53.9 ± 7.5 min of treadmill running. This end-Tcore value was primarily predicted by heart rate, sweat rate, differences between Tcore and Tskin , wet-bulb globe temperature, initial Tcore , running speed and maximal oxygen uptake, in this order of importance (ß power values corresponded to 0.462, -0.395, 0.393, 0.327, 0.277, 0.244 and 0.228, respectively). In conclusion, several factors predict Tcore in athletes subjected to self-paced running under environmental heat stress. Moreover, considering the conditions investigated, heart rate and sweat rate, two practical (non-invasive) variables, have the highest predictive power.

Determinants of body core temperatures at fatigue in rats subjected to incremental-speed exercise: The prominent roles of ambient temperature, distance traveled, initial core temperature, and measurement site.

Understanding the factors that underlie the physical exercise-induced increase in body core temperature (TCORE) is essential to developing strategies to counteract hyperthermic fatigue and reduce the risk of exertional heatstroke. This study analyzed the contribution of six factors to TCORE attained at fatigue in Wistar rats (n = 218) subjected to incremental-speed treadmill running: ambient temperature (TAMB), distance traveled, initial TCORE, body mass, measurement site, and heat loss index (HLI). First, we ran hierarchical multiple linear regression analyses with data from different studies conducted in our laboratory (n = 353 recordings). We observed that TAMB, distance traveled, initial TCORE, and measurement site were the variables with predictive power. Next, regression analyses were conducted with data for each of the following TCORE indices: abdominal (TABD), brain cortex (TBRAIN), or colonic (TCOL) temperature. Our findings indicated that TAMB, distance traveled (i.e., an exercise performance-related variable), initial TCORE, and HLI predicted the three TCORE indices at fatigue. Most intriguingly, HLI was inversely related to TABD and TBRAIN but positively associated with TCOL. Lastly, we compared the temperature values at fatigue among these TCORE indices, and the following descendent order was noticed - TCOL, TABD, and TBRAIN - irrespective of TAMB where experiments were conducted. In conclusion, TCORE in rats exercised to fatigue depends primarily on environmental conditions, performance, pre-exercise TCORE, and measurement site. Moreover, the influence of cutaneous heat loss on TCOL is qualitatively different from the influence on TABD and TBRAIN, and the temperature values at fatigue are not homogenous within the body core.

Norepinephrine modulation of heat dissipation in female rats lacking estrogen.

Postmenopausal hot flushes are caused by lack of estradiol (E2) but their neuroendocrine basis is still poorly understood. Here, we investigated the interrelationship between norepinephrine and hypothalamic neurons, with emphasis on kisspeptin neurons in the arcuate nucleus (ARC), as a regulatory pathway in the vasomotor effects of E2. Ovariectomized (OVX) rats displayed increased tail skin temperature (TST), and this increase was prevented in OVX rats treated with E2 (OVX + E2). Expression of Fos in the hypothalamus and the number of ARC kisspeptin neurons coexpressing Fos were increased in OVX rats. Likewise, brainstem norepinephrine neurons of OVX rats displayed higher Fos immunoreactivity associated with the increase in TST. In the ARC, the density of dopamine-ß-hydroxylase (DBH)-immunoreactive (ir) fibers was not altered by E2 but, importantly, DBH-ir terminals were found in close apposition to kisspeptin cells, revealing norepinephrine inputs to ARC kisspeptin neurons. Intracerebroventricular injection of the α2-adrenergic agonist clonidine (CLO) was used to reduce central norepinephrine release, confirmed by the decreased 3-methoxy-4-hydroxyphenylglycol/norepinephrine ratio in the preoptic area and ARC. Accordingly, CLO treatment in OVX rats reduced ARC Kiss1 mRNA levels and TST to the values of OVX + E2 rats. Conversely, CLO stimulated Kiss1 expression in the anteroventral periventricular nucleus (AVPV) and increased luteinizing hormone secretion. These findings provide evidence that augmented heat dissipation in OVX rats involves the increase in central norepinephrine that modulates hypothalamic areas related to thermoregulation, including ARC kisspeptin neurons. This neuronal network is suppressed by E2 and its imbalance may be implicated in the vasomotor symptoms of postmenopausal hot flushes.

Hypothalamic Expression of Estrogen Receptor Isoforms Underlies Estradiol Control of Luteinizing Hormone in Female Rats.

Luteinizing hormone (LH) secretion during the ovarian cycle is governed by fluctuations in circulating estradiol (E2) that oppositely regulate kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) of the hypothalamus. However, how these effects are orchestrated to achieve fertility is unknown. Here, we have tested the hypothesis that AVPV and ARC neurons have different sensitivities to E2 to coordinate changes in LH secretion. Cycling and ovariectomized rats with low and high E2 levels were used. As an index of E2 responsiveness, progesterone receptor (PR) was expressed only in the AVPV of rats with high E2, showing the preovulatory LH surge. On the other hand, kisspeptin neurons in the ARC responded to low E2 levels sufficient to suppress LH release. Notably, the Esr1/Esr2 ratio of gene expression was higher in the ARC than AVPV, regardless of E2 levels. Accordingly, the selective pharmacological activation of estrogen receptor α (ERα) required lower doses to induce PR in the ARC. The activation of ERß, in turn, amplified E2-induced PR expression in the AVPV and the LH surge. Thus, ARC and AVPV neurons are differently responsive to E2. Lower E2 levels activate ERα in the ARC, whereas ERß potentiates the E2 positive feedback in the AVPV, which appears related to the differential Esr1/Esr2 ratio in these 2 brain areas. Our findings provide evidence that the distinct expression of ER isoforms in the AVPV and ARC plays a key role in the control of periodic secretion of LH required for fertility in females.

Early maternal separation alters the activation of stress-responsive brain areas in adulthood.

The expression of c-Fos protein has been extensively used as a marker of neuronal activation in response to stressful stimuli. Early maternal separation (MS) is a model of early life adversity that affects the responsiveness of the brain areas to stressors. Thus, this study examined the impact of early MS on activating stress-responsive areas in the brain of adult rats in response to physical (ether) or psychological (restraint) stressors. Male pups were divided for the MS or non-handled (NH) groups. The MS was carried out daily between the 2nd and 14th day of postnatal life and consisted in removing the dams from the cage for 180 min. The rats were then subjected to experimental protocols of restraint or ether exposure at 10-12 weeks old. The rats were anesthetized 90 min after exposure to the stressors, and their brains were prepared for immunohistochemical analysis of c-Fos immunoreactive (c-Fos-ir) neurons in the hypothalamic paraventricular nucleus (PVN), supraoptic nucleus (SON), medial preoptic area (MPA), medial amygdaloid nucleus (MeA), locus coeruleus (LC), and nucleus of the solitary tract (NST). The MS-group presented 86%, 125%, 73%, 56%, and 137% higher c-Fos-ir neurons in the LC, PVN, SON, MPA, and MeA, respectively, compared to NH-group in response to the restraint stressor. In addition, the MS-group presented 180%, 137%, 170%, and 138% higher c-Fos-ir neurons for the ether exposure in the LC, PVN, MPA, and MeA, respectively. Our results show a greater increase in neuronal activation in the MS group, indicating that early life adversity can induce reprogramming in the brain response to stress in adulthood.

Storage Duration Affects the Quantification of Oxidative Stress Markers in the Gastrocnemius, Heart, and Brain of Mice Submitted to a Maximum Exercise.

This study investigated the effect of sample storage duration on the quantification of oxidative stress markers in the gastrocnemius, heart, and brain of mice submitted to a maximum swimming exercise. Thiobarbituric acid reactive substances (TBARSs), protein carbonyl derivatives, total antioxidant capacity (TAC), and the activity of superoxide dismutase (SOD) and catalase (CAT) were quantified in fresh tissues and in samples stored at -80°C for 1, 3, or 6 months, from exercised (n = 13) and nonexercised mice (n = 13). Except for protein carbonyl derivatives in the heart, the exercise resulted in the modification of all markers in all fresh-evaluated samples (p < 0.001). The storage duration did not modify the effect of exercise on protein carbonyl derivatives and TAC. TBARS was stable for 3 months in the gastrocnemius and for 1 month in frozen heart and brain. Accordingly, the exercise effect on TBARS levels observed in fresh samples was absent in the gastrocnemius frozen for 6 months (p = 0.98) and in the heart and brain frozen for 3 months (p = 0.07 and 0.28, respectively) or more (p = 0.21 for heart and p > 0.99 for brain). In addition, CAT and SOD activities were reduced by storage duration in all tissues evaluated (p < 0.05). Our findings show that sample storage duration alters the quantification of oxidative stress markers in mice submitted to maximum exercise, and its effect is tissue and marker dependent. Some recommendations to achieve more accurate and reproducible data in the exercise physiology and oxidative stress markers field are presented.

Core temperature circadian rhythm across aging in Spontaneously Hypertensive Rats.

The purpose of this study was to evaluate the circadian rhythm of core temperature (Tcore) across aging in Spontaneously Hypertensive Rats (SHR) with comparison to the two rat strains often used as their normotensive control animals, namely, Wistar (WIS) and Wistar Kyoto (WKY). METHODS: WIS, WKY and SHR rats were subdivided into three different groups according their age: WIS16, WIS48, WIS72, WKY16, WKY48, WKY72, SHR16, SHR48 and SHR72 weeks-old. Body mass and blood pressure were periodically measured along the experiments. All animal group had their circadian rhythm of Tcore evaluated over three consecutive days (72 h) by telemetry using an implanted temperature sensor. The Tcore circadian rhythm was averaged in 1-h blocks and analyzed using the cosinor method. RESULTS: Sixteen-week-old SHR (SHR16) presented higher Tcore than WIS16 (from 06am to 06pm) and WKY16 (from 07am to 06pm). Both normotensive groups exhibited increases in Tcore during circadian rhythm with aging. The cosinor analysis showed no differences between strains and ages for the acrophase. An age effect on the SHR strain (SHR16 < SHR72) was observed regarding the amplitude. SHR16 had higher values regarding MESOR compared to WIS16 and WKY16. In addition, WIS72 and WKY72 showed higher values than WIS16 and WKY16, respectively. Finally, no differences were observed in the strength rhythm analysis. CONCLUSIONS: SHR presented impaired thermoregulatory control at only 16 weeks of age when showing a higher body temperature during the activity phase, while other circadian rhythm parameters showed no differences across aging. Therefore, in taking our results as a whole we can conclude that WIS and WKY are appropriate Wistar strains to be used as normotensive controls for SHR.

Comparison of Physical Fitness and Anthropometrical Profiles Among Brazilian Female Soccer National Teams From U15 to Senior Categories.

ABSTRACT: Ramos, GP, Nakamura, FY, Penna, EM, Mendes, TT, Mahseredjian, F, Lima, AM, Garcia, ES, Prado, LS, and Coimbra, CC. Comparison of physical fitness and anthropometrical profiles among Brazilian female soccer national teams from U15 to senior categories. J Strength Cond Res 35(8): 2302-2308, 2021-This study aimed to compare anthropometric and physical fitness of Brazilian female national team soccer players from the U15 to senior categories, and to compare the physical performance between selected and nonselected players. Subjects included 231 athletes (U15, n = 46, U17, n = 49, U20, n = 98, and Senior, n = 38). Body mass, height, sum of skinfolds, squat jump (SJ), countermovement jump (CMJ), 20-m linear sprint, and Yo-Yo IR1 were assessed. The U15 players were shorter than all other groups (p < 0.01) and lighter than U20 players (p < 0.01). Regarding physical tests, Senior athletes presented higher SJ compared with U20, and both showed higher CMJ and SJ compared with the U15 and U17 (p < 0.05). Senior athletes were also faster than players of all other categories in 20-m sprint (p < 0.01) and covered the greatest distance in the Yo-Yo IR1 (p < 0.05). U20 were better in the Yo-Yo IR1 than the younger groups (p < 0.05). When comparing selected and nonselected players, no differences were identified in anthropometric measures (p > 0.05). However, selected players from U17, U20, and Senior teams showed better performance in Yo-Yo IR1 than nonselected ones (p < 0.05). Finally, selected senior athletes also presented higher CMJ and SJ than nonselected players (p < 0.05). These results suggest that, although there is a tendency for maintenance in anthropometric measures from the age of 15 years, there are substantial improvements in speed, lower-body power, and aerobic capacity from U20 age group. In addition, it seems that intermittent aerobic fitness contributes to the selection of players to international tournaments in national teams.

Exercise capacity in different stages of hypertension in spontaneously hypertensive rats.

BACKGROUND: The aim of the present study was to investigate the exercise capacity of hypertensive rats at different stages of development of hypertension and to determine the most suitable index to evaluate the exercise capacity in different strains. METHODS: Male spontaneously hypertensive rat (SHR) and normotensive Wistar rats (NWR) of 5, 8, 12 and 16 weeks were submitted to the exercise capacity test. The exercise running time was measured and the workload was calculated. RESULTS: Normotensive and hypertensive rats when assess the exercise capacity by exercise running time exhibited a reduction in exercise performance over time. Moreover, hypertensive rats showed lower exercise capacity compared to normotensive control when analyzed by workload. CONCLUSIONS: The present results indicate that hypertensive rats exhibit reduced exercise capacity compared to normotensive rats regardless of age assessed. Beside that, in experiments with strains with different body mass the most reliable index to assess exercise capacity is workload.

Insulin resistance is improved in high-fat fed mice by photobiomodulation therapy at 630 nm.

Photobiomodulation therapy (PBMT) in the infrared spectrum exerts positive effects on glucose metabolism, but the use of PBMT at the red spectrum has not been assessed. Male Swiss albino mice were divided into low-fat control and high-fat diet (HFD) for 12 weeks and were treated with red (630 nm) PBMT or no treatment (Sham) during weeks 9 to 12. PBMT was delivered at 31.19 J/cm2 , 60 J total dose per day for 20 days. In HFD-fed mice, PBMT improved glucose tolerance, insulin resistance and fasting hyperinsulinemia. PBMT also reduced adiposity and inflammatory infiltrate in adipose tissue. Phosphorylation of Akt in epididymal adipose tissue and rectus femoralis muscle was improved by PBMT. In epididymal fat PBMT reversed the reduced phosphorylation of AS160 and the reduced Glut4 content. In addition, PBMT reversed the alterations caused by HFD in rectus femoralis muscle on proteins involved in mitochondrial dynamics and ß-oxidation. In conclusion, PBMT at red spectrum improved insulin resistance and glucose metabolism in HFD-fed mice.

The time-course of thermoregulatory responses during treadmill running is associated with running duration-dependent hypothalamic neuronal activation in rats.

This study evaluated the hypothalamic neuronal activation during exercise and investigated whether this activation is related to heat storage and exercise duration. Rats were subjected to a treadmill running that was interrupted at three different moments: (1) at the early phase, when minimal heat dissipation occurred due to tail vasoconstriction and the tail skin temperature (Tskin) reached its nadir; (2) at the steady-state phase, when both the Tskin and core body temperature (Tcore) plateaued at a high level (~ 20 min); and (3) at fatigue, when Tcore and Tskin were still elevated. c-Fos expression in the medial and ventromedial preoptic areas (mPOA and vmPOA), median preoptic nucleus (MnPO), paraventricular and supraoptic nucleus (PVN and SON), and septohypothalamic nucleus (SHy) was determined. Exercise increased the expression of c-Fos in all brain areas, but with different activation patterns of activation. c-Fos expression in the SHy and vmPOA was similar in all exercising groups, while in the mPOA, MnPO, and PVN, c-Fos expression gradually increased during exercise. Increased c-Fos in the SON was only evident after 20 min of exercise. Neuronal activation in the mPOA, MnPO, PVN, and SON was positively correlated with both exercise duration and heat storage. Our findings indicate that with the exception of SON, the brain areas analyzed are recruited following small changes in Tcore (~ 0.5 °C), while the SON is recruited only when Tcore reaches higher values (greater than 1.0 °C increase). c-Fos expression in the PVN, mPOA, MnPO, and SON is also influenced by exercise duration, which does not occur in the SHy and vmPOA.

Hypothalamic endocannabinoid signalling modulates aversive responses related to panic attacks.

Recurrent panic attacks, comprising emotional and cardiovascular aversive responses, are common features in panic disorder, a subtype of anxiety disorder. The underlying brain circuitry includes nuclei of the hypothalamus, such as the dorsomedial hypothalamus (DMH). The endocannabinoid system has been proposed to modulate several biological processes in the hypothalamus. Thus, we tested the hypothesis that hypothalamic endocannabinoid signalling controls aversive responses in an animal model of panic attacks. Local infusion of NMDA into the DMH of rats induced panic-like behaviour. This effect was prevented by local, but not intraperitoneal, injection of a 2-arachidonoylglycerol (2-AG) hydrolysis inhibitor (MAGL inhibitor, URB602). The anandamide hydrolysis inhibitor (FAAH inhibitor), URB597, was ineffective. The anti-aversive action of URB602 was reversed by CB1 and CB2 antagonists (AM251 and AM630, respectively), and mimicked by CB1 and CB2 agonists (ACEA and JWH133, respectively). URB602 also prevented the cardiovascular effects of DMH-stimulation in anaesthetised animals. None of the treatments modified blood corticosterone levels. In conclusion, facilitation of 2-AG-signalling in the DMH modulates panic-like responses. The possible mechanisms comprise activation of both CB1 and CB2 receptors in this brain region.

Rats with higher intrinsic exercise capacities exhibit greater preoptic dopamine levels and greater mechanical and thermoregulatory efficiencies while running.

The present study investigated whether intrinsic exercise capacity affects the changes in thermoregulation, metabolism and central dopamine (DA) induced by treadmill running. Male Wistar rats were subjected to three incremental exercises and ranked as low-performance (LP), standard-performance (SP), and high-performance (HP) rats. In the first experiment, abdominal (TABD) and tail (TTAIL) temperatures were registered in these rats during submaximal exercise (SE) at 60% of maximal speed. Immediately after SE, rats were decapitated and concentrations of DA and 3,4-dihydroxyphenylacetic acid (DOPAC) were determined in the preoptic area (POA). In the second experiment, oxygen consumption was measured and mechanical efficiency (ME) was calculated in these rats during an incremental exercise. HP rats ran for longer periods and were fatigued with higher TABD values, with no difference in TTAIL. Nevertheless, thermoregulatory efficiency was higher in HP rats, compared with other groups. DA and DOPAC concentrations in the POA were increased by SE, with higher levels in HP compared with LP and SP rats. V̇o2 also differed between groups, with HP rats displaying a lower consumption throughout the incremental exercise but a higher V̇o2 at fatigue. ME, in turn, was consistently higher in HP than in LP and SP rats. Thus, our results show that HP rats have greater TABD values at fatigue, which seem to be related to a higher dopaminergic activity in the POA. Moreover, HP rats exhibited a greater thermoregulatory efficiency during exercise, which can be attributed to a lower V̇o2, but not to changes in tail heat loss mechanisms. NEW & NOTEWORTHY Our findings reveal that rats with higher intrinsic exercise capacities have greater thermoregulatory efficiencies and increased dopaminergic activity in the preoptic area, a key brain area in thermoregulatory control, while exercising. Moreover, higher intrinsic exercise capacities are associated with decreased oxygen consumption for a given exercise intensity, which indicates greater mechanical efficiencies. Collectively, these findings help to advance our knowledge of why some rats of a given strain can exercise for longer periods than others.

Activity Profiles in U17, U20, and Senior Women's Brazilian National Soccer Teams During International Competitions: Are There Meaningful Differences?

Ramos, GP, Nakamura, FY, Penna, EM, Wilke, CF, Pereira, LA, Loturco, I, Capelli, L, Mahseredjian, F, Silami-Garcia, E, and Coimbra, CC. Activity profiles in U17, U20, and senior women's Brazilian national soccer teams during international competitions: are there meaningful differences? J Strength Cond Res 33(12): 3414-3422, 2019-The aim of this study was to compare locomotor activity profiles of Brazilian top-class female soccer players competing at distinct age brackets (under 17 [U17], under [U20], and senior). External match load of 14 U17, 14 U20, and 17 senior female soccer players competing in 6-7 full official international matches were assessed using global positioning systems. Total distance covered, distance covered in high intensity (15.6-20 km·h), distance covered in sprints (sprint: >20 km·h), number of accelerations (Acc) >1 m·s, decelerations (Dec) >-1 m·s, and Player Load generally increased across the age brackets (U17

Fast and slow-twitching muscles are differentially affected by reduced cholinergic transmission in mice deficient for VAChT: A mouse model for congenital myasthenia.

Congenital myasthenic syndromes (CMS) result from reduced cholinergic transmission at neuromuscular junctions (NMJs). While the etiology of CMS varies, the disease is characterized by muscle weakness. To date, it remains unknown if CMS causes long-term and irreversible changes to skeletal muscles. In this study, we examined skeletal muscles in a mouse line with reduced expression of Vesicular Acetylcholine Transporter (VAChT, mouse line herein called VAChT-KDHOM). We examined this mouse line for several reasons. First, VAChT plays a central function in loading acetylcholine (ACh) into synaptic vesicles and releasing it at NMJs, in addition to other cholinergic nerve endings. Second, loss of function mutations in VAChT causes myasthenia in humans. Importantly, VAChT-KDHOM present with reduced ACh and muscle weakness, resembling CMS. We evaluated the morphology, fiber type (myosin heavy chain isoforms), and expression of muscle-related genes in the extensor digitorum longus (EDL) and soleus muscles. This analysis revealed that while muscle fibers atrophy in the EDL, they hypertrophy in the soleus muscle of VAChT-KDHOM mice. Along with these cellular changes, skeletal muscles exhibit altered levels of markers for myogenesis (Pax-7, Myogenin, and MyoD), oxidative metabolism (PGC1-α and MTND1), and protein degradation (Atrogin1 and MuRF1) in VAChT-KDHOM mice. Importantly, we demonstrate that deleterious changes in skeletal muscles and motor deficits can be partially reversed following the administration of the cholinesterase inhibitor, pyridostigmine in VAChT-KDHOM mice. These findings reveal that fast and slow type muscles differentially respond to cholinergic deficits. Additionally, this study shows that the adverse effects of cholinergic transmission, as in the case of CMS, on fast and slow type skeletal muscles are reversible.

Physical Exercise-Induced Cardiovascular and Thermoregulatory Adjustments Are Impaired in Rats Subjected to Cutaneous Artery Denervation.

This study aimed to investigate the chronic effects of caudal artery denervation on morphometric parameters of the tail vascular smooth muscle and on physical exercise-induced thermoregulatory and cardiovascular adjustments in rats. Male Wistar rats were subjected to caudal artery denervation or the sham procedure. Approximately 26-28 days after these procedures, their thermoregulatory and cardiovascular parameters were evaluated at rest and during or following a fatiguing treadmill run. At the end of the experiments, the rats were euthanized, and samples of their tails were removed to evaluate morphometric parameters of the vascular smooth muscle surrounding the caudal artery. Denervated rats showed morphological adaptations, including increased arterial wall thickness and wall-to-lumen ratios. In resting rats and following the fatiguing exercise, caudal artery denervation barely affected the thermoregulatory and cardiovascular parameters evaluated. By contrast, caudal artery denervation attenuated the increase in tail skin temperature, decreased the spontaneous baroreflex sensitivity, and exacerbated the increases in mean arterial pressure in exercising rats. The increased wall-to-lumen ratio of denervated rats correlated negatively with the maximum tail skin temperature attained or cutaneous heat loss sensitivity but correlated positively with the maximum diastolic blood pressure attained during exercise. In conclusion, cutaneous denervation induces vascular remodeling characterized by morphological adaptations of the tail vascular smooth muscle. This vascular remodeling likely underlies the impaired tail heat loss and blood pressure adjustments in denervated rats subjected to physical exercise. Therefore, we have highlighted the importance of cutaneous vascular innervation integrity in thermal and cardiovascular control in stress-challenged rats. In this sense, our findings advance the understanding of thermoregulatory and cardiovascular system reactions after a sustained cutaneous vascular innervation injury, which is essential for the treatment of some diseases, such as Parkinson's disease and type 1 and type 2 diabetes mellitus.