Muscle Heat Shock Protein Research Articles

Skeletal Muscle Heat Shock Protein Content and the Repeated Bout Effect.

The "Repeated Bout Effect" (RBE) occurs when a skeletal muscle is preconditioned with a few lengthening contractions (LC) prior to exposing the muscle to a greater number of LC. The preconditioning (PC) results in significantly less damage and preservation of force. Since it takes only a few LC to increase muscle heat shock protein (HSP) content, it was of interest to examine the relationship between HSPs and the RBE. To do this, one tibialis anterior (TA) muscle from Sprague-Dawley rats (n = 5/group) was preconditioned with either 0, 5, or 15 lengthening contractions (LC) and exposed to a treatment of 60 LC 48 h later. Preconditioning TA muscles with 15 LC, but not 5 LC, significantly elevated muscle αB-crystallin (p < 0.05), HSP25 (p < 0.05), and HSP72 content (p < 0.001). These preconditioned TA muscles also showed a significantly (p < 0.05) reduced loss of active torque throughout the subsequent 60 LC. While there was a trend for all preconditioned muscles to maintain higher peak torque levels throughout the 60 LC, no significant differences were detected between the groups. Morphologically, preconditioned muscles appeared to show less discernible muscle fiber damage. In conclusion, an elevated skeletal muscle HSP content from preconditioning may contribute to the RBE.

Greater physiological resistance to heat may favour an invasive freshwater turtle, enabling it to outcompete native species in a changing climate

Abstract Climate warming and biological invasion can interact to affect ecosystems, and the results of such interactions depend on whether invaders show physiological advantages in their responses to warming environments as compared with native species after the establishment and local adaptation. However, it has rarely been evaluated. The present study compared the heat tolerance of a globally invasive turtle, the red‐eared slider Trachemys scripta elegans, and two co‐occurring native turtle species in China, the Chinese soft‐shelled turtle Pelodiscus sinensis and Chinese pond turtle Mauremys reevesii, after acclimation in the same thermal environment. The expression patterns of heat shock factor 1 (HSF1), multiple heat shock proteins (HSPs) and telomere reverse transcriptase (TERT), and changes in relative telomere length (RTL) were then evaluated in liver and muscle of turtles under thermal stress. The results showed that T. scripta elegans had greater physiological resistance to heat than the co‐occurring native turtle species, and that this higher tolerance was accompanied by a higher temperature induction of the peak expression of inducible HSPs in liver and a higher onset temperature for the main inducible HSPs in muscle. During thermal stress, T. scripta elegans showed a better ability to maintain the expression levels of TERT under extremely hot conditions, whereas high temperatures inhibited TERT in muscles of native turtle species. Meanwhile, thermal stress did not cause telomere erosion in any of the three turtle species and some treatments can lead to slightly longer telomeres in T. scripta elegans or M. reevesii. Overall, the invasive turtle species showed higher heat tolerance and physiological advantages in enduring hot weather in comparison to the co‐occurring native turtle species. This may favour these invaders in situations of climate warming. Our study highlights the role of physiological adaptations displayed by invaders in achieving advantages over native species under climate change.

Thermal Effect on Heat Shock Protein 70 Family to Prevent Atherosclerotic Cardiovascular Disease.

Heat shock protein 70 (HSP70) is a chaperone protein induced by various stresses on cells and is involved in various disease mechanisms. In recent years, the expression of HSP70 in skeletal muscle has attracted attention for its use as a prevention of atherosclerotic cardiovascular disease (ASCVD) and as a disease marker. We have previously reported the effect of thermal stimulation targeted to skeletal muscles and skeletal muscle-derived cells. In this article, we reported review articles including our research results. HSP70 contributes to the improvement of insulin resistance as well as chronic inflammation which are underlying pathologies of type 2 diabetes, obesity, and atherosclerosis. Thus, induction of HSP70 expression by external stimulation such as heat and exercise may be useful for ASCVD prevention. It may be possible to induce HSP70 by thermal stimulus in those who have difficulty in exercise because of obesity or locomotive syndrome. It requires further investigation to determine whether monitoring serum HSP70 concentration is useful for ASCVD prevention.

Molecular investigations of the effect of thermal manipulation during embryogenesis on muscle heat shock protein 70 and thermotolerance in broiler chickens

The objective of this study was to elucidate the optimum protocol timing of thermal manipulation (TM) during embryogenesis, which underline genetic improvement of muscle thermotolerance acquisition. For the present study, 1,440 fertile eggs were divided randomly and equally into control (37.8 °C with 56% relative humidity) and four thermally manipulated groups (TM1, TM2, TM3, and TM4) subjected to 39 °C for 18 h with 65% relative humidity daily during different embryonic periods. Then, at day 35 post-hatch, all groups [...]

Evaluating the role of dietary plant extracts to allow adaptation to thermal stress in a cold stream ornamental fish, Botia rostrata (Günther, 1868)

Increases in ambient temperature affect the biochemical status of fish, and dietary supplementation with bioactive phytoconstituents may promote resilience against environmental stress. This study evaluated the impact of three plant extracts on the biochemical status of a cold stream fish Botia rostrata (Günther, 1868) under high temperatures. After 1 month dietary supplementation separately with Mucuna pruriens methanol extract (0.25 g/kg feed), Tribulus terrestris ethanol extract (0.5 g/kg feed) and Basella alba ethanol extract (1.0 g/kg feed), juvenile fish (Wt. 4.3 ± 0.5g) were exposed to different sublethal heat stress [28 ± 0.5 °C (T1), 32 ± 0.5 °C (T2), 36 ± 0.5 °C (T3)]. Control fish were fed a diet without any plant extract and maintained at 24 ± 0.5 °C. Serum and muscle tissues were collected to measure different biochemical parameters, muscle metabolic enzymes and molecular chaperons before and after heat stress. Before stress, the group fed the Mucuna diet showed significant (P < 0.05) increases in serum glucose [+10.92%], protein [+18.93%], muscle heat shock protein (HSP) 90 [+8.6%] compared to the control group. No significant change (P > 0.05) of stress parameters was observed between control, Tribulus and Basella fed fish. The control group exposed to T3 showed significant differences (P < 0.05) in protein [-26.19%], lactate dehydrogenase [+93.69%], fructose 1,6 bisphosphate [-35.19%], phosphorylase ‘a’ [+35.72%], HSP60 [+69.54%], HSP70 [+84.85%], HSP90 [+92.07%], heat shock factor (HSF) 1 [+88.48%] suggesting susceptibility of Botia to this temperature. Among the three plant extracts, Mucuna methanol extract was effective to enhance resistance against temperature-induced biochemical alterations. After exposure to T3, only the fish fed Mucuna diet showed no mortality. Fish fed Mucuna diet exposed to 36 ± 0.5 °C showed significantly higher (P < 0.05) glucose [+42.82%], protein [+11.98%], citrate synthase [+59.81%], phosphorylase ‘a’ [+14.96%], Glucose 6 phosphate dehydrogenase [+60.87%], HSP60 [+34.13%], HSP70 [+41.42%], HSP90 [+65.91%], HSF1 [+61.32%] compared to those in Mucuna fed fish maintained at 24 ± 0.5 °C. These results highlight temperature-induced biochemical alterations in Botia and point towards the potential use of Mucuna in overcoming such adverse high thermal stress.

Ad Libitum Western Diet Feeding Does Not Alter Basal Skeletal Muscle Heat Shock Protein Expression in Sedentary or Aerobically Trained Young Rats

Poor dietary habits can lead to obesity and insulin resistance—both of which can impair basal heat shock protein (HSP) expression and the HSP stress response in skeletal muscle. It remains unclear if impairments in HSP expression occur during the early stages of diet-induced obesity and metabolic dysfunction. We determined if basal HSP expression (HSP70, HSP60, HSP25) was impaired in sedentary or exercised rats following the onset of diet-induced obesity. Male Long-Evans rats (N=6-7/group) were assigned to a Western diet (WD) or purified diet (PD). Animals were divided into sedentary (WD and PD) or exercise-trained (WD+Ex and PD+Ex) groups and fed &lt;/span&gt;&lt;em&gt;&lt;span&gt;ad libitum&lt;/span&gt;&lt;/em&gt;&lt;span&gt; for 12-weeks. WD animals displayed higher body mass, fat mass, blood glucose, and HOMA-IR scores compared to PD (p&lt;0.05). Exercise attenuated elevations in HOMA-IR and body mass for WD+Ex (p&gt;0.05) but did not prevent elevations in fat mass or blood glucose when compared to controls. Basal HSP (HSP70, HSP60, HSP25) expression was not impaired in sedentary WD animals when compared to PD (p&gt;0.05) or when WD+Ex was compared to PD+Ex (p&gt;0.05). Exercise training elevated HSP70 expression in the gastrocnemius muscle (GAST) (p&lt;0.05), but not in the soleus (SOL) (p&gt;0.05) in WD+Ex and PD+Ex animals. HSP60 and pHSP25 were unaffected by exercise training (GAST and SOL, p&gt;0.05). The onset of diet-induced obesity does not impair skeletal muscle HSP expression in sedentary or exercised animals. Thus, obesity and symptomology of metabolic dysfunction may occur before reductions in skeletal muscle HSP expression.

Ovariectomy alters lengthening contraction induced heat shock protein expression.

Estrogen appears to play a role in minimizing skeletal muscle damage as well as regulating the expression of the protective heat shock proteins (HSPs). To clarify the relationship between estrogen, muscle HSP content, and muscle damage, tibialis anterior (TA) muscles from ovary-intact (OVI; n = 12) and ovariectomized (OVX; 3 weeks, n = 12) female Sprague-Dawley rats were subjected to either 20 or 40 lengthening contractions (LCs). Twenty-four hours after stimulation, TA muscles were removed, processed, and assessed for HSP25 and HSP72 content as well as muscle (damage) morphology. No differences in muscle contractile properties were observed in TA muscles between OVI and OVX animals for peak torque during the LCs. In unstressed TA muscles, the basal expression of HSP72 expression was decreased in OVX animals (P < 0.05) while HSP25 content remained unchanged. Following 20 LCs, HSP25 content was elevated (P < 0.05) in TA muscles from OVX animals but unchanged in muscles from OVI animals. Following 40 LCs, HSP25 content was elevated (P < 0.01) in TA muscles from both OVI and OVX animals while HSP72 content was elevated only in TA muscles from OVI animals (P < 0.05). Taken together, these data suggest the loss of ovarian hormones, such as estrogen, may impair the skeletal muscle cellular stress response thereby rendering muscles more susceptible to certain types of contraction induced damage. Novelty Ovariectomy alters muscle HSP72 content. Muscle contractile measures are maintained following ovariectomy.

Leucine-Enriched Essential Amino Acids Improve Recovery from Post-Exercise Muscle Damage Independent of Increases in Integrated Myofibrillar Protein Synthesis in Young Men.

Background: Leucine-enriched essential amino acids (LEAAs) acutely enhance post-exercise myofibrillar protein synthesis (MyoPS), which has been suggested to be important for muscle repair and recovery. However, the ability of LEAAs to concurrently enhance MyoPS and muscle damage recovery in free-living humans has not been studied. Methods: In a randomized, double-blind, placebo-controlled, parallel-group design, twenty recreationally active males consuming a controlled diet (1.2 g/kg/d of protein) were supplemented thrice daily with 4 g of LEAAs (containing 1.6 g leucine) or isocaloric placebo for four days following an acute bout of lower-body resistance exercise (RE). MyoPS at rest and integrated over 96 h of recovery was measured by D2O. Isometric and isokinetic torque, muscle soreness, Z-band streaming, muscle heat shock protein (HSP) 25 and 72, plasma creatine kinase (CK), and plasma interleukin-6 (IL-6) were measured over 96 h post-RE to assess various direct and indirect markers of muscle damage. Results: Integrated MyoPS increased ~72% over 96 h after RE (p < 0.05), with no differences between groups (p = 0.98). Isometric, isokinetic, and total peak torque decreased ~21% by 48 h after RE (p < 0.05), whereas total peak torque was ~10% greater overall during recovery in LEAAs compared to placebo (p < 0.05). There were moderate to large effects for peak torque in favour of LEAAs. Muscle soreness increased during recovery with no statistical differences between groups but small to moderate effects in favour of LEAAs that correlated with changes in peak torque. Plasma CK, plasma IL-6, and muscle HSP25 increased after RE (p < 0.05) but were not significantly different between groups (p ≥ 0.13). Consistent with a trend toward attenuated Z-band streaming in LEAAs (p = 0.07), muscle HSP72 expression was lower (p < 0.05) during recovery in LEAAs compared with placebo. There were no correlations between MyoPS and any measures of muscle damage (p ≥ 0.37). Conclusion: Collectively, our data suggest that LEAAs moderately attenuated muscle damage without concomitant increases in integrated MyoPS in the days following an acute bout of resistance exercise in free-living recreationally active men.

HSP72 expression is specific to skeletal muscle contraction type.

Exercise is capable of inducing the cellular stress response and increasing skeletal muscle heat shock protein (HSP) content. HSPs function as molecular chaperones and play roles in facilitating protein folding thereby contributing to muscle proteostasis. To determine the relationship between muscle contraction types, muscle damage, and HSP content, one tibialis anterior (TA) muscle from male Sprague-Dawley rats (n = 5/group) was electrically stimulated while actively lengthening (LC), shortening (SC), or remaining to stagnate (IC) for 15 repetitions (3 sets of five). Two additional LC groups underwent 5 and 10 repetitions. Maximal tetanic tension (MTT) was recorded prior to (pre) and at 5min after (post) the last contraction. Twenty-four hours after stimulation, TA muscles were removed, processed, and assessed for damage and for HSP25 and HSP72 content. Post-MTT was significantly decreased following 15 LCs, (24%; p < 0.05) but not following 15 SCs or 15 ICs. Post-MTT was also decreased by 8% (p < 0.05), and 18% (p < 0.05) for muscles subjected to 5 and 10 LCs, respectively. HSP72 content increased after all LCs conditions but not following ICs or SCs. HSP25 content remained unchanged following all contractions. Similarly, muscle damage was observed only after LCs and not after other contraction types. In conclusion, muscle HSP72 content can be increased with as few as 5 maximal lengthening contractions and appears to be related to muscle damage. This may have important implications for muscle rehabilitation and exercise training programs.

Comparative assessment of heat stress induced changes in carcass traits, plasma leptin profile and skeletal muscle myostatin and HSP70 gene expression patterns between indigenous Osmanabadi and Salem Black goat breeds

The primary objective of the study was to compare the impact of heat stress on meat production characteristics of Osmanabadi and Salem Black breed goats based on changes in carcass characteristics, meat quality attributes, plasma leptin concentration, skeletal muscle myostatin and heat shock protein 70 (HSP70) gene expression patterns. The goats were randomly distributed into four groups: OSC (n = 6; Osmanabadi Control), OSHS (n = 6; Osmanabadi Heat Stress), SBC (n = 6; Salem Black Control) and SBHS (n = 6; Salem Black Heat Stress). The animals were slaughtered at the end of the study and their meat characteristics were assessed. This study established the impact of heat stress on a wide variety of carcass and meat quality characteristics in OS and SB goat breeds. The results from the study also provided some crucial evidence for a better resilience capacity of Salem Black breed as compared to Osmanabadi goats in maintaining the meat production during heat stress. The study also established plasma leptin and HSP70 genes to be the ideal biomarkers to reflect the impact of heat stress on meat characteristics in indigenous goats.

AICAR Treatment Does Not Prevent Increases in Exercise Capacity or Muscle Heat Shock Protein 25 with Treadmill Training in Mice

Exercise and 5‐aminoimidazole‐4‐carboxamide‐1‐β‐D‐ribofuranoside (AICAR) are agonists of AMP‐activated protein kinase (AMPK) and are used in type II diabetes treatment. Treatment effectiveness may be due to AMPK activation and up‐regulation of heat shock proteins (Hsps) in skeletal muscle, including Hsp25 and αB‐crystallin. Decreased Hsp25 expression in skeletal muscle is associated with insulin resistance in rats and data in both animals and humans suggests that increased Hsp expression in skeletal muscle may contribute to the prevention and treatment of insulin resistance. However, some evidence in both animals and humans suggests the combination of exercise and AMPK‐activating drugs such as AICAR may decrease exercise‐training adaptations. These experiments tested the hypothesis that AICAR + treadmill training (TM) would attenuate increases in exercise capacity, muscle force, and Hsp expression compared to training alone. Adult, male C57 mice were divided into 4 groups (n = 8–10/group): 1‐Placebo, 2‐AICAR, 3‐Placebo + TM, and 4‐Aicar + TM. Groups received daily placebo or AICAR with or without TM over 7 days. Plantarflexor muscle force and fatigue (% of max force after 10 contractions) were measured in vivo and exercise capacity was assessed with pre‐ and post‐treadmill tests. Muscle Hsp25 and αB‐crystallin protein levels were quantified with western blot. Data was statistically analyzed with 2‐way ANOVAs and post‐hoc tests. AICAR + TM did not affect training‐associated increases in exercise capacity compared to Placebo + TM (D time pre to post: 903 ± 164 vs. 1,188 ± 99 sec. for AICAR and TM, respectively, p&lt;0.05). Muscle force was unchanged with AICAR in either TM or sedentary groups compared to placebo (Placebo: 1.2 ± 0.07 vs. 1.3± 0.07 and AICAR: 1.4 ± 0.08 vs. 1.5 ± 0.12 g/g body mass, for sedentary and TM, respectively, p&lt;0.05). Fatigability was greater with AICAR in sedentary mice; however, AICAR + TM decreased fatigability compared to AICAR alone (p&lt;0.05). TM increased Hsp25 levels independent of treatment (Placebo: 0.09 ± 0.01 vs. 0.15 ± 0.01 and AICAR 0.15 ± 0.02 vs. 0.17 ±0.02 AU, for sedentary and TM, respectively, p&lt;0.05) and AICAR increased Hsp25 in the sedentary group compared to placebo (0.15 ± 0.02 vs. 0.09 ± 0.01 AU, p&lt;0.05). AICAR prevented the TM‐associated increase in αB‐crystallin compared to placebo (Placebo: 0.11 ± 0.02 vs. 0.17 ± 0.01 and AICAR: 0.10 ± 0.01 vs. 0.01 ± 0.02 AU, for sedentary and TM, respectively, p&lt;0.05). These findings suggest AICAR does not impair training‐associated increases in exercise capacity or Hsp25 muscle protein or negatively impact muscle force production. Taken together, these treatments could positively impact type II diabetics who often have reduced exercise capacity and skeletal muscle Hsp25 levels.Support or Funding InformationSupported by APS UGSRF.

The cellular stress response of rat skeletal muscle following lengthening contractions.

The cellular stress response of the rat tibialis anterior (TA) muscle was investigated following 20, 40, or 60 lengthening contractions (LCs) using an in vivo model of electrical stimulation. Muscles were removed at 0, 1, 3, or 24 h after LCs and assessed for heat shock transcription factor (HSF) activation, heat shock protein (HSP) content, and/or morphological evidence of muscle fibre damage. When compared with the first muscle contraction, peak muscle torque was reduced by 26% (p < 0.05) after 20 LCs and further reduced to 56% and 60% (p < 0.001) after 40 and 60 LCs, respectively. Following 60 LCs, HSF activation was detected at 0, 1, and 3 h but was undetectable at 24 h. Hsp72 content was elevated at 24 h after 20 LCs (2.34 ± 0.37 fold, p < 0.05), 40 LCs (3.02 ± 0.31 fold, p < 0.01), and 60 LCs (3.37 ± 0.21 fold, p < 0.001). Hsp25 content increased after 40 (2.36 ± 0.24 fold, p < 0.01) and 60 LCs (2.80 ± 0.37 fold, p < 0.01). Morphological assessment of TA morphology revealed that very few fibres were damaged following 20 LCs while multiple sets of LCs (40 and 60) caused greater amounts of fibre damage. Electron microscopy showed disrupted Z-lines and sarcomeres were detectable in some muscles fibres following 20 LCs but were more prevalent and severe in muscles subjected to 40 or 60 LCs. These results suggest LCs elevate HSP content by an HSF-mediated mechanism (60 LC) and a single set of 20 LCs is capable of increasing muscle HSP content without causing significant muscle fibre damage.

Effects of heated hydrotherapy on muscle HSP70 and glucose metabolism in old and young vervet monkeys.

Increasing heat shock protein 70 (HSP70) in aged and/or insulin-resistant animal models confers benefits to healthspan and lifespan. Heat application to increase core temperature induces HSPs in metabolically important tissues, and preliminary human and animal data suggest that heated hydrotherapy is an effective method to achieve increased HSPs. However, safety concerns exist, particularly in geriatric medicine where organ and cardiovascular disease commonly will preexist. We evaluated young vervet monkeys compared to old, insulin-resistant vervet monkeys (Chlorocebus aethiops sabaeus) in their core temperatures, glucose tolerance, muscle HSP70 level, and selected safety biomarkers after 10 sessions of hot water immersions administered twice weekly. Hot water immersion robustly induced the heat shock response in muscles. We observed that heat-treated old and young monkeys have significantly higher muscle HSP70 than control monkeys and treatment was without significant adverse effects on organ or cardiovascular health. Heat therapy improved pancreatic responses to glucose challenge and tended to normalize glucose excursions. A trend for worsened blood pressure and glucose values in the control monkeys and improved values in heat-treated monkeys were seen to support further investigation into the safety and efficacy of this intervention for metabolic syndrome or diabetes in young or old persons unable to exercise.

Exercise Induces Skeletal Muscle Heat Shock Protein Expression Independent of Dietary Macronutrient Content

Diet‐induced obesity is directly associated with the development of hyperglycemia and stress kinase activation in target tissues, leading to impaired glucose tolerance and insulin resistance (IR) in skeletal muscle. Heat shock protein (HSP) induction is shown to attenuate the development of hyperglycemia and IR by precluding the activation of stress kinases. While HSP‐mediated improvements in metabolic function are observed with acute heat treatment, little is known about the effects of other known inducers of HSPs in skeletal muscle such as exercise and dietary modification. Therefore, the objective of this study was to compare the effects of dietary modification and chronic exercise on skeletal muscle HSP expression and fasting blood glucose levels (GLUC) in rats. Male Long‐Evans rats (N=27), were randomly assigned into Western diet (WD, 40% FAT/43% CHO/17% PRO) or vegan style Daniel Fast diet (DF, 25% FAT/60% CHO/15% PRO) groups. Rats were further divided into exercise (+EX) (25m·min−1 for 35 min·day−1, 3X/week) and sedentary groups. All rats were fed ad libitum for a 12 week intervention period. Soleus and gastrocnemius tissues were harvested and analyzed via western immunoblotting and densitometry for HSP70, pHSP27, HSP27, and HSP60 content. GLUC was measured using a standard enzymatic colorimetric assay. A two‐way ANOVA, with Tukey's post hoc test, was used to examine the differences in HSP expression between the diet and exercise groups for each tissue. A Pearson product‐moment correlation was used to determine if there was an association between HSP expression and GLUC. After 12 weeks of chronic exercise and dietary modification, gastrocnemius samples from the WD+EX and DF+EX groups had significant (P &lt; 0.05) increases in HSP70 expression (+194% and +196% respectively) in comparison to sedentary controls. Non‐significant changes in HSP70 expression were also seen in the soleus of WD+EX (+140%) and DF+EX (+185%) groups. There was no change in pHSP27, HSP27, and HSP60 due to exercise for both gastrocnemius and soleus tissues. Additionally, no change in HSP expression (HSP70, pHSP27, HSP27, and HSP60) was observed when comparing diets (WD:DF, WD+EX:DF+EX) for either tissue. GLUC values in the WD (183.47 mg/dL ± 18.27), WD+EX (158.34 mg/dL ± 24.39), and DF (129.34 mg/dL ± 22.86) groups were indicative of rats being hyperglycemic, while values in the DF+EX (112.95 mg/dL ± 7.19) group were within the normal physiologic range. Unlike previous reports, no correlation was observed between HSP expression and the degree of hyperglycemia (HSP70:GLUC, r = −.139). In conclusion, our data suggests that chronic exercise induces a uniform increase in HSP70 expression in rats fed either a Western diet or vegan style Daniel Fast diet. As such, exercise may be an effective means to obtain the therapeutic effects of HSP expression in hyperglycemic rats regardless of dietary macronutrient content.

Skeletal muscle Heat shock protein 60 increases after endurance training and induces peroxisome proliferator-activated receptor gamma coactivator 1 α1 expression.

Heat shock protein 60 (Hsp60) is a chaperone localizing in skeletal muscle mitochondria, whose role is poorly understood. In the present study, the levels of Hsp60 in fibres of the entire posterior group of hindlimb muscles (gastrocnemius, soleus, and plantaris) were evaluated in mice after completing a 6-week endurance training program. The correlation between Hsp60 levels and the expression of four isoforms of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α) were investigated only in soleus. Short-term overexpression of hsp60, achieved by in vitro plasmid transfection, was then performed to determine whether this chaperone could have a role in the activation of the expression levels of PGC1α isoforms. The levels of Hsp60 protein were fibre-type specific in the posterior muscles and endurance training increased its content in type I muscle fibers. Concomitantly with the increased levels of Hsp60 released in the blood stream of trained mice, mitochondrial copy number and the expression of three isoforms of PGC1α increased. Overexpressing hsp60 in cultured myoblasts induced only the expression of PGC1 1α, suggesting a correlation between Hsp60 overexpression and PGC1 1 α activation.

Bos indicus cattle possess greater basal concentrations of HSP27, alpha B-crystallin, and HSP70 in skeletal muscle in vivo compared with cattle.

The objectives of the present study were to evaluate the basal concentrations of heat shock proteins (HSP) between and cattle and to determine if HSP basal concentrations change as an animal matures. A total of 40 cattle were used in a 2 × 2 factorial design to evaluate the effects of genotype and age (heifers and mature cows) on basal concentrations of heat shock protein 27 (HSP27), α B-crystallin (Cryab), and heat shock protein 70 (HSP70). Each experimental group of 10 animals was sampled on a separate day over a period of 4 wk during July 2014. A muscle sample was collected from the longissimus thoracis (LT) and concentrations of HSP were quantified using ELISA. There were no significant differences in HSP concentration for the interaction between age and genotype or for age alone. cattle had greater ( < 0.05) basal concentrations of HSP27, Cryab, and HSP70 in the LT than cattle. The results of this study show that basal in vivo HSP concentrations differ between and cattle. However, further studies are needed to investigate the relationship between HSP concentrations and meat tenderness with respect to genotypes to see if HSP concentrations account for at least some variability in tenderness differences.

Effect of dietary manganese on antioxidant status and expression levels of heat-shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures.

To investigate the effect of Mn on antioxidant status and expression levels of heat-shock proteins/factors in tissues of laying broiler breeders subjected to heat challenge, we used a completely randomised design (n 6) with a factorial arrangement of 2 environmental temperatures (normal, 21 (sem 1)°C and high, 32 (sem 1)°C)×3 dietary Mn treatments (an Mn-unsupplemented basal diet (CON), or a basal diet supplemented with 120 mg Mn/kg diet as inorganic Mn sulphate (iMn) or organic Mn proteinate (oMn)). There were no interactions (P>0·10) between environmental temperature and dietary Mn in all of the measured indices. High temperature decreased (P<0·003) Mn content, and also tended (P=0·07) to decrease copper zinc superoxide dismutase (CuZnSOD) activity in the liver and heart. However, an increased manganese superoxide dismutase (MnSOD) activity (P<0·05) and a slight increase of malondialdehyde level (P=0·06) were detected in breast muscle. Up-regulated (P<0·05) expression levels of heat-shock factor 1 (HSF1) and HSF3 mRNA and heat-shock protein 70 (HSP70) mRNA and protein were found in all three tissues. Broiler breeders fed either iMn or oMn had higher tissue Mn content (P<0·0001), heart MnSOD and CuZnSOD activities (P<0·01) and breast muscle MnSOD protein levels (P<0·05), and lower (P<0·05) breast muscle HSP70 mRNA and protein levels than those fed CON. Broiler breeders fed oMn had higher (P<0·03) bone Mn content than those fed iMn. These results indicate that high temperature decreases Mn retention and increases HSP70 and HSF1, HSF3 expression levels in tissues of laying broiler breeders. Furthermore, dietary supplementation with Mn in either source may enhance heart antioxidant ability and inhibit the expression of HSP70 in breast muscle. Finally, the organic Mn appears to be more available than inorganic Mn for bone in laying broiler breeders regardless of environmental temperatures.

Skeletal muscle heat shock protein 60 increases after endurance training in mice and induces peroxisome proliferation-activated receptor-γ coactivator-1 α1 expression

Heat shock protein (Hsp60) is a mitochondrial chaperonin whose unconventional cellular localizations and functions are discovered day by day. In the present study, the levels of Hsp60 in fibres of the soleus muscle and its correlation to the expression of four isoforms of peroxisome proliferation-activated receptor-γ (PPAR-γ) coactivator-1α (PGC1α) were investigated in 72 young (7-weeks old) healthy male mice (BALB/c AnNHsd) at baseline and after completing a 6-week endurance training program. The mice were assigned to one of the two experimental groups: SED (sedentary) or TR (trained). Short-term overexpression of hsp60, achieved by in vitro plasmid transfection, was then performed to determine whether this chaperonin could have a role in the activation of the expression levels of PGC-1α isoforms. The levels of Hsp60 protein were fibre-type specific in the posterior muscles at baseline, and endurance training increased its content in type I muscle fibers. Concomitantly with the increased levels of Hsp60 released in the blood stream of trained mice, mitochondrial copy number and the expression of three isoforms of PGC-1α increased. Overexpressing hsp60 in cultured myoblasts induced only the expression of PGC-1 α1, letting us suppose a direct correlation between Hsp60 overexpression and PGC-1 α1 activation. Overall, these results suggest that during endurance training Hsp60 is upregulated and activates the mitochondrial biogenesis pathway, probably as a response to the oxidative stress induced by exercise. This study reveals a molecular response of skeletal muscle to a mechanical stress induced by training which involves the molecular chaperonin Hsp60 and the transcriptional co-activator PGC-1 α1. The role of these proteins in aerobic adaptation and pathological conditions as cancer cachexia warrants further investigations.

Xenobiotic metabolism modulation after long-term temperature acclimation in juveniles of Solea senegalensis

The Senegalese sole, Solea senegalensis, originates from subtropical waters and displays great adaptability to environmental factors such as temperature. A comprehensive study on the effect of long-term temperature acclimation on xenobiotic metabolism, along with the assessment of other parameters related to physiological status, was designed to characterize the response of this species to temperature fluctuations within a realistic range. S. senegalensis juveniles were acclimated for a period of 60 days to two different ambient temperatures, 15 and 20 °C. Several hepatic, gill, muscular and plasmatic parameters were measured over time at the two temperatures. The lower temperature triggered, over time, the synthesis of hepatic microsomal cytochrome P450-related enzymes (e.g. 7-ethoxyresorufin O-deethylase (EROD), carboxylesterases, and the conjugating enzyme uridine diphosphate glucuronosyltransferase and, more significantly, EROD activity in gills. The antioxidant enzyme activities: catalase and glutathione reductase in liver were positively correlated to temperature. Plasmatic parameters (glucose, lactate, triglycerides and osmolality) were consistent with a good physiological status of the experimental fish. The expression of heat shock proteins in muscle did not significantly change in the two temperature groups. The results evidenced that the subtropical species S. senegalensis also uses the temperature compensation strategy to different degrees for most biotransformation enzymes; this response was more intense and faster in gills than in liver. This compensatory strategy did not apply to antioxidant enzymes and GST. The present findings highlight the need to consider the thermal history of the fish when using S. senegalensis as a sentinel in a biomarker-based pollution monitoring study. The fish plasticity on its strategy of physiological adaptation to temperature changes could contribute to explain the success in the geographical expansion of this species.

Dietary antioxidants at supranutritional doses modulate skeletal muscle heat shock protein and inflammatory gene expression in sheep exposed to heat stress.

The objective of this study was to investigate the effects of chronic heat (thermal) stress and dietary antioxidant supplementation on the expression of heat shock proteins and inflammatory genes in the skeletal muscle of sheep. Twenty-four Merino × Poll Dorset crossbred ewes were allocated to either a control (10 IU vitamin E and 0.24 mg Se/kg DM) or high-antioxidant (VitE+Se; 100 IU vitamin E and 1.20 mg Se/kg DM) diet and were exposed to 2 thermal (temperature) treatments (thermoneutral [TN]: 18°C-21°C and 26%-30% relative humidity; heat stress [HS]: 28°C-40°C and 40%-50% relative humidity) for 1 wk. Physiological parameters were recorded daily, and muscle biopsies were conducted at the end of thermal treatments. Total RNA was extracted from muscle samples and reverse transcribed to cDNA for real-time PCR analysis. Respiration rates and rectal temperature were increased in response to HS (84.2 vs. 161 breaths per minute and 39.52°C vs. 40.06°C for TN and HS conditions, respectively; P < 0.001). There were interactions between dietary and thermal treatments, indicating that dietary antioxidant supplementation reduced respiration rate (P = 0.097) and rectal temperature (P = 0.086) of sheep during HS but not TN conditions. Skeletal muscle heat shock transcription factor 1 (HSF1) mRNA abundance was increased by HS (1.3-fold; P < 0.050) but was not changed (P = 0.77) by dietary antioxidant supplementation. The expression of skeletal muscle heat shock protein 70 (HSP70) mRNA was increased (P < 0.001) 3.5-fold by HS and tended (P = 0.08) to be increased by dietary antioxidant supplementation. Although there were no main effects of diet (P = 0.42) or HS (P = 0.47) on skeletal muscle HSP90 mRNA expression, there was an interaction (P = 0.040) such that HSP90 mRNA expression was increased (P = 0.010) in antioxidant-supplemented sheep under HS compared to TN conditions. Skeletal muscle nuclear factor kappa B (NF-κB) and tissue necrosis factor α (TNF-α) mRNA abundances were increased by exposure to heat (5.2-fold, P = 0.005 for NF-κB; 5.7-fold, P = 0.013 for TNF-α) ,but there was no main effect (P > 0.05) of dietary antioxidant supplementation. There was, however, an interaction between thermal and dietary treatments such that dietary antioxidant supplementation ameliorated the effect of HS on NF-κB and TNF-α mRNA expression. Taken together, these results indicate that high dietary antioxidants modulate skeletal muscle expression of heat shock proteins, proinflammatory cytokine, and NF-κB transcription, which may protect against HS in sheep.