Capilarización y tipos de fibras en la musculatura esquelética de aves

[spa] Se estudió, mediante métodos histoquímicos, la musculatura esquelética de 4 especies de aves. Se analizaron las características metabólicas de los diferentes tipos de fibras, su inervación, distribución y morfometría; así como también la capilarización y otros parámetros relacionados con el aporte de O(2) al músculo esquelético. La tesis está dividida en tres partes. la primera, claramente metodológica, consiste en dos técnicas de tinción histoquímica: una de ellas permite cuantificar el aporte capilar al músculo; y la otra pone de manifiesto, sobre un mismo corte de tejido, las características de inervación y el tipo de fibra muscular. La segunda parte, tomando como modelo la paloma, es un estudio monográfico sobre los tipos de fibras de aves en diversos músculos locomotores y posturales. Finalmente, la tercera parte consiste en un estudio sobre la musculatura motora implicada en el vuelo, la natación y la locomoción terrestre de tres especies de aves salvajes con hábitos locomotores distintos: el ánade real, la focha común y la gaviota patiamarilla

Un ejemplo de respuesta adaptativa integrada: la aclimatación humana a la altitud

Se describen las respuestas fisiológicas que el ser humano desarrolla en respuesta a la exposición a la altitud geográfica. Se describen no sólo las alteraciones debidas a una mala coordinación de los ajustes fisiológicos desencadenados durante la aclimatación a la altura sino también sus manifestaciones clínicas más relevantes. Se detallan los mecanismos moleculares subyacentes a tales respuestas y cómo su mejor conocimiento puede permitir aplicar la exposición intermitente a hipoxia como una herramienta útil para la resolución o alivio de determinadas alteraciones y patologías

Edible microalgae and their bioactive compounds in the prevention and treatment of metabolic alterations

Marine and freshwater algae and their products are in growing demand worldwide because of their nutritional and functional properties. Microalgae (unicellular algae) are probably one of the foods of the future for nutritional and environmental reasons. They are sources of high-quality protein and bioactive molecules with potential application against the modern epidemics of obesity and diabetes while they may decisively contribute to a sustainable world through carbon dioxide fixation and minimization of agricultural land use. This paper reviews the current knowledge related to the effect of edible microalgae on the metabolic alterations known as metabolic syndrome (MS). The microalgae include Chlorella, Spirulina (Arthrospira spp.) and Tetraselmis spp., as well as Isochrysis spp. and Nannochloropsis spp. as candidates for use in humans. Chlorella has shown antioxidant, antidiabetic, immunomodulatory, antihypertensive, and antihyperlipidemic effects in humans and other mammals. The components of the microalgae reviewed is suggesting they may be effective against MS at two levels, namely the early stages in the development of insulin resistance (IR) and the later stages when pancreatic -cell function is already compromised. The active components could act at both levels because of their biochemical properties as antioxidant scavengers and anti-inflammatory lipid mediators. Their action should be attributed to the presence of carotenoids and -3 PUFAs (EPA/DHA), prebiotic polysac-charides, phenolics, anti-hypertensive peptides, several pigments such as phycobilins and phycocyanin, and some vitamins such as folate. As a source of high-quality protein, including an array of bioactive molecules with potential action against the modern epidemics of obesity and diabetes, microalgae are proposed as excellent food for the future. Moreover, their incorporation to human diet would decisively contribute to a more sustainable world because of their role in carbon dioxide fixation and reducing the use of land for agricultural purposes

Histomorphological and functional contralateral symmetry in the gastrocnemius muscles of the laboratory rat

It is usual in anatomical and physiological research to assess the effects of some intervention on extremities (e.g., training programmes or injury recovery protocols) using one muscle for the intervention and its contralateral as control. However, the existence of laterality (left-handedness or right-handedness) in athletes of different specialties is widely recognized. In rats, gastrocnemius is one of the muscles most widely used because of its importance in locomotion and high relative limb mass. Since we have not found studies reporting laterality assessment on the morphology and function in rat gastrocnemius, our study aimed to evaluate the fibre histochemical, morphometrical and muscle force contractile properties between right and left gastrocnemius of the laboratory rat. Fibre type proportion, fibre morphometrical measurements, muscle capillarization and muscle force properties were analysed in the right and left gastrocnemius of six male rats. No statistically significant differences (p=0.265) were found in gastrocnemius to body weight ratio (¿) between right (6.55±0.40) and left (6.49±0.40) muscles. The muscles analysed showed a great degree of heterogeneity in fibre type distribution, having three clearly distinguished regions named red, mixed and white. In the three regions, there were no statistical differences in fibre type proportions between right and left gastrocnemius, as is indicated by the p-values (from 0.203 to 0.941) obtained after running t-Student paired tests for each fibre type. When analysing fibre cross-sectional area, individual fibre capillarization and fibre circularity, no significant differences between right and left gastrocnemius in any of these morphometrical parameters were found in any muscle region or fibre type. Most of the p-values (70%) resulting from running t-Student paired tests were higher than 0.400, and the lowest p-value was 0.115. Seemingly, global capillary and fibre densities were not statistically different between right and left sides in all muscle regions with p-values ranging from 0.337 to 0.812. Force parameters normalized to gastrocnemius mass (mN·g-1) did not show any significant difference between right (PF=74.0±13.4, TF=219.4±13.0) and left (PF=70.9±10.7, TF=213.0±18.0) muscles with p=0.623 (PF) and p=0.514 (TF). Twitch time parameters (ms) also lacked significant differences between the two sides (CT: 43.4±8.6 vs 45.0±14.3, P=0.639; HRT: 77.6±15.0 vs 82.3±25.3, p=0.475). Finally, both muscles also showed similar (p=0.718) fatigue properties. We did find an absence of laterality at the morphological and functional levels, which raises the possibility of using right and left gastrocnemius muscles interchangeably for experimental designs where one muscle is used to analyse data after a physiological intervention and its contralateral muscle plays the control role, thus allowing unbiased paired comparisons to derive accurate conclusions

Physiological effects of intermittent passive exposure to hypobaric hypoxia and cold in rats

The benefits of intermittent hypobaric hypoxia (IHH) exposure for the health and its potential use as a training tool are well-documented. However, since hypobaric hypoxia and cold are environmental factors always strongly associated in the biosphere, additive or synergistic adaptations could have evolved in animals' genomes. For that reason, the aim of the present study was to investigate body composition, hematological and muscle morphofunctional responses to simultaneous intermittent exposure to hypoxia and cold. Adult male rats were randomly divided into 4 groups: 1) Control, maintained in normoxia at 25°C (CTRL); 2) IHH exposed 4h/day at 4,500 m (HYPO); 3) Intermittent cold exposed 4h/day at 4°C (COLD); and 4) Simultaneously cold and hypoxia exposed (COHY). At the end of 9 and 21 days of exposure, blood was withdrawn and gastrocnemius and tibialis anterior muscles, perigonadal and brown adipose tissue, diaphragm and heart were excised. Gastrocnemius transversal sections were stained for myofibrillar ATPase and succinate dehydrogenase for fibre typing; and for endothelial ATPase to assess capillarisation. HIF 1α, VEGF and GLUT1 from gastrocnemius samples were semi-quantified by Western blotting. COLD and HYPO underwent physiological adjustments such as higher brown adipose tissue weight and increase in blood-related oxygen transport parameters, while avoiding some negative effects of the chronic exposure to cold and hypoxia, such as body weight and muscle mass loss. COHY presented an additive erythropoietic response and was prevented from right ventricle hypertrophy. Intermittent cold exposure induced muscle angiogenesis and IHH seems to indicate better muscle oxygenation through fibre area reduction

Effect of hypobaric hypoxia on hematological parameters related to oxygen transport, blood volume and oxygen consumption in adolescent endurance-training athletes

Background/Objective:To analyze the effect of altitude on hematological and cardiorespiratory variables in adolescent athletes participating in aerobic disciplines. Methods:21 females and 89 males participated in the study. All were adolescent elite athletes engaged in endurance sports (skating, running and cycling) belonging to two groups: permanent residents in either low altitude (LA, 966 m) or moderate altitude (MA, 2640 m). Hematocrit (Hct), hemoglobin concentration ([Hb]), total hemoglobin mass (Hbt), blood, plasma and erythrocyte volumes (BV, PV and EV), VO2peak and other cardiorespiratory parameters were evaluated. Results:Sex differences were evident both in LA and HA skating practitioners, the males having higher significant values than the females in oxygen transport-related hematological parameters and VO2peak. The effect of altitude residence was also observed in Hct, [Hb], Hbt and EV with increased (14%–18%) values in the hematological parameters and higher EV (5%–24%). These results matched the significantly higher values of VO2peak measured in MA residents. However, BV and PV did not show differences between LA and MA residents in any case. Sports discipline influenced neither the hematological variables nor most of the cardiorespiratory parameters. Conclusions:LA and MA adolescent skaters showed sex differences in hematological variables. Endurance-trained male adolescent residents at MA had an increased erythropoietic response and a higher VO2peak compared to their counterparts residing and training at LA. These responses are similar in the three aerobic sports studied, indicating that the variables described are highly sensitive to hypoxia irrespective of the sports discipline

Gestational exercise increases male offspring's maximal workload capacity early in life

Mothers' antenatal strategies to improve the intrauterine environment can positively decrease pregnancy-derived intercurrences. By challenging the mother-fetus unit, gestational exercise (GE) favorably modulates deleterious stimuli, such as high-fat, high-sucrose (HFHS) diet-induced adverse consequences for offspring. We aimed to analyze whether GE alters maternal HFHS-consumption effects on male offspring's maximal workload performance (MWP) and in some skeletal muscle (the soleus SOL and the tibialis anterior TA) biomarkers associated with mitochondrial biogenesis and oxidative fitness. Infant male Sprague-Dawley rats were divided into experimental groups according to mothers' dietary and/or exercise conditions: offspring of sedentary control diet-fed or HFHS-fed mothers (C-S or HFHS-S, respectively) and of exercised HFHS-fed mothers (HFHS-E). Although maternal HFHS did not significantly alter MWP, offspring from GE dams exhibited increased MWP. Lower SOL AMPk levels in HFHS-S were reverted by GE. SOL PGC-1α, OXPHOS C-I and C-IV subunits remained unaltered by maternal diet, although increased in HFHS-E offspring. Additionally, GE prevented maternal diet-related SOL miR-378a overexpression, while upregulated miR-34a expression. Decreased TA C-IV subunit expression in HFHS-S was reverted in HFHS-E, concomitantly with the downregulation of miR-338. In conclusion, GE in HFHS-fed dams increases the offspring's MWP, which seems to be associated with the intrauterine modulation of SM mitochondrial density and functional markers

Swimming-induced exercise promotes hypertrophy and vascularization of fast skeletal muscle fibres and activation of myogenic and angiogenic transcriptional programs in adult zebrafish

The adult skeletal muscle is a plastic tissue with a remarkable ability to adapt to different levels of activity by altering its excitability, its contractile and metabolic phenotype and its mass. We previously reported on the potential of adult zebrafish as a tractable experimental model for exercise physiology, established its optimal swimming speed and showed that swimming-induced contractile activity potentiated somatic growth. Given that the underlying exercise-induced transcriptional mechanisms regulating muscle mass in vertebrates are not fully understood, here we investigated the cellular and molecular adaptive mechanisms taking place in fast skeletal muscle of adult zebrafish in response to swimming. Fish were trained at low swimming speed (0.1 m/s; non-exercised) or at their optimal swimming speed (0.4 m/s; exercised). A significant increase in fibre cross-sectional area (1.290 ± 88 vs. 1.665 ± 106 μm2) and vascularization (298 ± 23 vs. 458 ± 38 capillaries/mm2) was found in exercised over non-exercised fish. Gene expression profiling by microarray analysis evidenced the activation of a series of complex transcriptional networks of extracellular and intracellular signaling molecules and pathways involved in the regulation of muscle mass (e.g. IGF-1/PI3K/mTOR, BMP, MSTN), myogenesis and satellite cell activation (e.g. PAX3, FGF, Notch, Wnt, MEF2, Hh, EphrinB2) and angiogenesis (e.g. VEGF, HIF, Notch, EphrinB2, KLF2), some of which had not been previously associated with exercise-induced contractile activity. The results from the present study show that exercise-induced contractile activity in adult zebrafish promotes a coordinated adaptive response in fast muscle that leads to increased muscle mass by hypertrophy and increased vascularization by angiogenesis. We propose that these phenotypic adaptations are the result of extensive transcriptional changes induced by exercise. Analysis of the transcriptional networks that are activated in response to exercise in the adult zebrafish fast muscle resulted in the identification of key signaling pathways and factors for the regulation of skeletal muscle mass, myogenesis and angiogenesis that have been remarkably conserved during evolution from fish to mammals. These results further support the validity of the adult zebrafish as an exercise model to decipher the complex molecular and cellular mechanisms governing skeletal muscle mass and function in vertebrates

Inter-individual different responses to continuous and interval training in recreational middle-aged women runners

A crucial subject in sports is identifying the inter-individual variation in response to training, which would allow creating individualised pre-training schedules, improving runner's performance. We aimed to analyse heterogeneity in individual responses to two half-marathon training programmes differing in running volume and intensity in middle-aged recreational women. Twenty women (40±7 years, 61±7kg, 167±6cm, VO2max=48±6 mL·kg-1·min-1) underwent either moderate-intensity continuous (MICT) or high-intensity interval (HIIT) 12-week training. They were evaluated before and after training with maximal incremental tests in the laboratory (VO2max) and in the field (time to exhaustion, TTE; short interval series and long run). All the women participated in the same half-marathon and their finishing times were compared with their previous times. Although the improvements in the mean finishing times were not significant, MICT elicited a greater reduction (3min 50s, P=0.298), with more women (70%) improving on their previous times, than HIIT (reduction of 2min 34s, P=0.197, 50% responders). Laboratory tests showed more differences in the HIIT group (P=0.008), while both groups presented homogeneous significant (P<0.05) increases in TTE. Both in the short interval series and in the long run, HIIT induced better individual improvements, with a greater percentage of responders compared to MICT (100% versus 50% in the short series and 78% versus 38% in the long run). In conclusion, variability in interindividual responses was observed after both MICT and HIIT, with some participants showing improvements (responders) while others did not (non-responders) in different performance parameters, reinforcing the idea that individualised training prescription is needed to optimise performance

A semiquantitative scoring tool to evaluate eccentric exercise-induced muscle damage in trained rats

Unaccustomed eccentric exercise is a welldocumented cause of exercise-induced muscle damage. However, in trained subjects muscle injury involves only light or moderate tissue damage. Since trained rats are widely used as a model for skeletal muscle injury, here we propose a semiquantitative scoring tool to evaluate muscle damage in trained rats. Twenty male Sprague-Dawley rats were trained for two weeks following a two-week preconditioning period, and randomly divided into two groups: control rats (CTL; n=5) and rats with eccentric exercise-induced muscle damage (INJ; n=15). Injured rats were sacrificed at three time points: 1, 3 and 7 days post injury (n=5 each). Transverse sections from the right soleus were cut (10 μm) and stained with haematoxylineosin. Samples were evaluated by two groups of observers (four researchers experienced in skeletal muscle histopathology and four inexperienced) using the proposed tool, which consisted of six items organised in three domains: abnormal fibre morphology, necrotic/(re) degenerating fibres (muscle fibre domain), endomysial and perimysial infiltration (inflammatory state domain) and endomysium and perimysium distension (interstitial compartment domain). We observed the expected time course in the six evaluated items. Furthermore, agreement among observers was evaluated by measuring the Intraclass Correlation Coefficient (ICC). Within the experienced group, items from the muscle fibre and interstitial compartment domains showed good agreement and the two items from the infiltration compartment domain showed excellent agreement. In conclusion, the proposed tool allowed quick and correct evaluation of light to moderate muscle damage in trained rats with good agreement between observers