GABAergic basal forebrain projections to the periaqueductal gray promote food consumption, reward and predation

Behaviors central to the procurement and consumption of food are among those most fundamental to survival, but their inappropriate expression can lead to overeating and obesity. Nevertheless, we have a poor understanding of circuits that promote feeding independent of physiological demand. Here we demonstrate that activation of basal forebrain (BF) GABAergic neurons results in consumption of food as well as non-food items in well-fed mice, and performance of fictive eating in the absence of ingestible materials. In addition, stimulation of these cells disrupts defensive threat responses and elicits reward-like motivational effects. Finally, BF GABAergic activity triggers skilled predatory attacks of live prey and prey-like objects, but not social targets. These effects were entirely recapitulated by selective stimulation of BF GABAergic projections to the periaqueductal gray (PAG). Our results outline a potent circuit mechanism for increased feeding through recruitment of distinct but synergistic behaviors, and add to growing evidence that PAG is an important integrator of feeding-related activity.

Inclusion of sprints during moderate-intensity continuous exercise enhances post-exercise fat oxidation in young males

To assess the physiological demand of including high-intensity efforts during continuous exercise, we designed a randomized crossover study, where 12 physically active young males executed three different exercises in random order: FATmax - continuous exercise at the highest fat oxidation zone (FATmax); 2min-130% - FATmax interspersed by a 2-min bout at 130% of the maximal oxygen uptake associated intensity (iV̇O2max); and 20s:10s-170% - FATmax interspersed by four 20-s bouts at 170%iV̇O2max interpolated by 10s of passive recovery. We measured oxygen uptake (V̇O2), blood lactate concentration ([LAC]), respiratory exchange rate (RER), fat and carbohydrate (CHO) oxidation. For statistical analyses, repeated measures ANOVA was applied. Although no differences were found for average V̇O2 or carbohydrate oxidation rate, the post-exercise fat oxidation rate was 37.5% and 50% higher during 2min-130% and 20s:10s-170%, respectively, compared to FATmax, which also presented lower values of RER during exercise compared to 2min-130% and 20s:10s-170% (p<0.001 in both), and higher values post-exercise (p=0.04 and p=0.002, respectively). The [LAC] was higher during exercise when high-intensity bouts were applied (p<0.001 for both) and higher post-exercise on the intermittent one compared to FATmax (p=0.016). The inclusion of high-intensity efforts during moderate-intensity continuous exercise promoted higher physiological demand and post-exercise fat oxidation. Novelty bullets • The inclusion of 2-min efforts modifies continuous exercise demands • Maximal efforts can increase post-exercise fat oxidation • 2-min maximal efforts, continuous or intermittent, presents similar demands

Effectiveness of Mobile Technology in Managing Fatigue: Balert App

The performance of professional tasks with a high cognitive, emotional, and even physiological demand, can cause a state of mental fatigue, which implies attentional alterations, greater errors in the tasks performed and a decrease in personal and work productivity caused by a deterioration of the cognitive control processes. The present study presents a mobile phone application named BAlert that allows monitoring and controlling the body's fatigue processes based on the scores obtained in the Stroop effect and the heart rate variability. A pilot study has been carried out with a sample of 63 adults who have used the application a total of 942 times. The results allow us to classify the subjects, by logistic regression analysis, in their fatigue levels in 74% of the occasions. These results highlight the importance of this mobile application to control work fatigue processes in different possible scenarios (military, health, sports, business, etc.).

Intestinal iron absorption is appropriately modulated to match physiological demand for iron in wild-type and iron-loaded Hamp (hepcidin) knockout rats during acute colitis

Mucosal damage, barrier breach, inflammation, and iron-deficiency anemia (IDA) typify ulcerative colitis (UC) in humans. The anemia in UC appears to mainly relate to systemic inflammation. The pathogenesis of this ‘anemia of inflammation’ (AI) involves cytokine-mediated transactivation of hepatic Hamp (encoding the iron-regulatory hormone, hepcidin). In AI, high hepcidin represses iron absorption (and iron release from stores), thus lowering serum iron, and restricting iron for erythropoiesis (causing anemia). In less-severe disease states, inflammation may be limited to the intestine, but whether this perturbs iron homeostasis is uncertain. We hypothesized that localized gut inflammation will increase overall iron demand (to support the immune response and tissue repair), and that hepatic Hamp expression will decrease in response, thus derepressing (i.e., enhancing) iron absorption. Accordingly, we developed a rat model of mild, acute colitis, and studied iron absorption and homeostasis. Rats exposed (orally) to DSS (4%) for 7 days had intestinal (but not systemic) inflammation, and biomarker analyses demonstrated that iron utilization was elevated. Iron absorption was enhanced (by 2-3-fold) in DSS-treated, WT rats of both sexes, but unexpectedly, hepatic Hamp expression was not suppressed. Therefore, to gain a better understanding of regulation of iron absorption during acute colitis, Hamp KO rats were used for further experimentation. The severity of DSS-colitis was similar in Hamp KOs as in WT controls. In the KOs, increased iron requirements associated with the physiological response to colitis were satisfied by mobilizing hepatic storage iron, rather than by increasing absorption of enteral iron (as occurred in WT rats). In conclusion then, in both sexes and genotypes of rats, iron absorption was appropriately modulated to match physiological demand for dietary iron during acute intestinal inflammation, but regulatory mechanisms may not involve hepcidin.

GABAergic basal forebrain projections to the periaqueductal gray promote food consumption, reward and predation

Behaviors central to the procurement and consumption of food are among those most fundamental to survival, but their inappropriate expression can lead to overeating and obesity. Nevertheless, we have a poor understanding of circuits that promote feeding independent of physiological demand. Here we demonstrate that activation of basal forebrain (BF) GABAergic neurons results in consumption of food as well as non-food items in well-fed mice, and performance of fictive eating in the absence of ingestible materials. In addition, stimulation of these cells disrupts defensive threat responses and elicits reward-like motivational effects. Finally, BF GABAergic activity triggers skilled predatory attack of live prey and prey-like objects, but not social targets. These effects were entirely recapitulated by selective stimulation of BF GABAergic projections to the periacqueductual gray (PAG). Our results outline a potent circuit mechanism for increased feeding through recruitment of distinct but synergistic behaviors, and add to growing evidence that PAG is an important integrator of feeding-related activity.

Physiological Demand, Metabolic Requirements, and User-Perceived Exertion of Immersive Virtual Reality Exergaming Incorporating an Adaptive Cable Resistance System: An Exploratory Study (Preprint)

BACKGROUND The intersection of games and exercise has sparked the growth of novel training systems with the potential to promote quality physical activity. Innovations in Immersive Virtual Reality (IVR) have propelled “exergaming” to the forefront of the fitness landscape. Researchers have yet to fully explore the physiological and metabolic efficacy and applications of the immersive environment and interactive programming. OBJECTIVE This study aimed to measure metabolic (i.e., energy expenditure (EE)) and physiological (i.e., heart rate (HR)) demands and subjective fatigue and enjoyment scores during a signature 30-minute IVR adaptive cable resistance exergaming session. METHODS Fourteen healthy, college-aged individuals (7 females) were initially acquainted with the equipment and acclimated to the virtual reality and gameplay dynamics. Participants then completed a signature 30-minute exergaming session using an IVR adaptive cable resistance system (Black Box VR ®) that incorporated chest press, squat, row, lat pulldown, overhead press, and stiff leg deadlift. During the session, a portable metabolic gas exchange analysis system assessed energy expenditure by indirect calorimetry and a chest-worn monitor captured heart rate. Immediately following the session, participants completed questionnaires including the Borg scale for Rating of Perceived Exertion (RPE), the Physical Activity Enjoyment Scale (PACES), and the Simulator Sickness Questionnaire (SSQ). RESULTS EE was greater in males compared to females in terms of kcal/min (P = 0.001), total kcal (P = 0.001), and metabolic equivalents (P = 0.029). Females demonstrated a higher average HR (P = 0.020) and HR as a percentage of theoretical HRmax (P = 0.018). The overall mean metabolic equivalent (MET) during the session was 12.9 (0.5). Men achieved greater volume of total weight lifted during the session (P < 0.001) and with chest press (P = 0.005), overhead press (P = 0.001), stiff-leg deadlift (P = 0.002), and squat (P = 0.015). For the questionnaires, the mean (SD) of RPE, PACES and SSQ was 14 (1), 4.31 (0.36) and 24.04 (24.13), respectively. CONCLUSIONS IVR exergaming with resistance cable training elicits substantial EE and very high physiological demand while attenuating perceived psychological and physical fatigue. Further investigations of IVR utility should explore nuanced muscle recruitment patterns during training and long-term regimen adherence.

Pituitary stem cells produce paracrine WNT signals to control the expansion of their descendant progenitor cells

In response to physiological demand, the pituitary gland generates new hormone-secreting cells from committed progenitor cells throughout life. It remains unclear to what extent pituitary stem cells (PSCs), which uniquely express SOX2, contribute to pituitary growth and renewal. Moreover, neither the signals that drive proliferation nor their sources have been elucidated. We have used genetic approaches in the mouse, showing that the WNT pathway is essential for proliferation of all lineages in the gland. We reveal that SOX2+ stem cells are a key source of WNT ligands. By blocking secretion of WNTs from SOX2+ PSCs in vivo, we demonstrate that proliferation of neighbouring committed progenitor cells declines, demonstrating that progenitor multiplication depends on the paracrine WNT secretion from SOX2+ PSCs. Our results indicate that stem cells can hold additional roles in tissue expansion and homeostasis, acting as paracrine signalling centres to coordinate the proliferation of neighbouring cells.

The Rating of Perceived Exertion Predicts Performance Loss and Physiological Demand in Vertical Jump Session Until Voluntary Failure

The aims of this study were (a) to assess the ability of the rating of perceived exertion (RPE) to predict performance loss (i.e. percent of drop in height relative to maximal height) of vertical jump session until voluntary failure, and (b) to determine the ability of RPE to describe the physiological demand of this session via heart rate monitor. Ten healthy men performed vertical jumps (counter-movement jump) until voluntary failure. Before session start maximal jump height for every subject was determined. Heart rate and RPE, separately for legs (RPE legs) and for breath (RPE breath), were recorded every ten jumps throughout the sessions. Results have shoved that RPE legs and performance loss have about 99% of same variance ( =0,9899; p<0,000), and RPE breath explains about 98% heart rate variance ( =0,9789; p<0,000) in vertical jump session until voluntary failure.

Pituitary stem cells produce paracrine WNT signals to control the expansion of their descendant progenitor cells

ABSTRACTIn response to physiological demand, the pituitary gland generates new hormone-secreting cells from committed progenitor cells throughout life. It remains unclear to what extent pituitary stem cells (PSCs), which uniquely express SOX2, contribute to pituitary growth and renewal. Moreover, neither the signals that drive proliferation nor their sources have been elucidated. We have used genetic approaches in the mouse, showing that the WNT pathway is essential for proliferation of all lineages in the gland. We reveal that SOX2+ stem cells are a key source of WNT ligands. By blocking secretion of WNTs from SOX2+ PSCs in vivo, we demonstrate that proliferation of neighbouring committed progenitor cells declines, demonstrating that progenitor multiplication depends on the paracrine WNT secretion from SOX2+ PSCs. Our results indicate that stem cells can hold additional roles in tissue expansion and homeostasis, acting as paracrine signalling centres to coordinate the proliferation of neighbouring cells.