Effects of chronic alcohol intoxication on aerobic exercise-induced adaptations in female mice.

Chronic alcohol intoxication decreases muscle strength/function and causes mitochondrial dysfunction. Aerobic exercise training improves mitochondrial oxidative capacity and increases muscle mass and strength. Presently, the impact of chronic alcohol on aerobic exercise-induced adaptations was investigated. Female C57BL/6Hsd mice were randomly assigned to one of four groups: control sedentary (CON SED; n = 26), alcohol sedentary (ETOH SED; n = 27), control exercise (CON EX; n = 28), and alcohol exercise (ETOH EX; n = 25). Exercise mice had running wheel access for 2 h a day, 7 days a week. All mice were fed either control or an alcohol-containing liquid diet. Grip strength testing and EchoMRI were performed before and after the interventions. After 6 wk, hindlimb muscles were collected for molecular analyses. A subset of mice performed a treadmill run to fatigue (RTF), then abstained from alcohol for 2 wk and repeated the RTF. Alcohol decreased lean mass and forelimb grip strength compared with control-fed mice. Alcohol blunted the exercise-induced increase in muscle mass (plantaris and soleus), type IIa fiber percentage in the plantaris, and run time to fatigue. Mitochondrial markers (Citrate synthase activity and Complex I-IV, COXIV and Cytochrome C protein expression) were increased with exercise regardless of ETOH in the gastrocnemius but not tibialis anterior muscle. Two weeks of alcohol abstinence improved RTF time in ETOH EX but not in ETOH SED. These data suggest that alcohol impairs some exercise-induced adaptations in skeletal muscle, but not all were negatively affected, indicating that exercise may be a beneficial behavior even while consuming alcohol.NEW & NOTEWORTHY Alcohol consumption during an aerobic exercise training period prevented training-induced increases in run to fatigue time and grip strength. Cessation of alcohol allowed for recovery of endurance performance within 2 wk. The worsened exercise performance after alcohol was unrelated to impairments in markers of mitochondrial health. Therefore, some adaptations to exercise training are impaired with alcohol use (endurance performance, muscle growth, and strength), while others remain mostly unaffected (mitochondrial health).

Impact of prior alcohol use on the subsequent development of cancer cachexia in male and female mice.

BACKGROUND: Alcohol is a carcinogen and its intake prior to developing cancer and throughout its duration exacerbates cancer cachexia in rodent models. However, the effects on cancer cachexia of stopping alcohol prior to tumor establishment are unknown. METHODS: Male and female mice consumed either a nonalcohol control liquid diet (CON) or a 20% ethanol (kcal/day) liquid diet (EtOH) for 6 weeks. All mice then consumed a control diet and mice in the cancer groups were inoculated with C26 colon cancer cells. Gastrocnemius muscles were collected and analyzed after ~2 weeks. RESULTS: Skeletal muscle weight and male epididymal and female perigonadal fat mass were reduced more by the combination of cancer and prior EtOH than either exposure alone in both males and females. In males, protein synthesis was reduced by 30% following alcohol exposure, while no reductions were observed in female mice. AMPK Thr172 phosphorylation was increased in both male and female EtOH-Cancer groups, while Akt Thr308 phosphorylation was reduced only among males in EtOH-Cancer mice. Substrates in the mTORC1 pathway were reduced by cancer in both males and females, but prior alcohol intake only reduced phosphorylation of 4E-BP1 Ser65 and rpS6 Ser240/244 to a greater extent in male, but not female, mice. Autophagic and proteasomal signaling were largely unaffected by prior alcohol intake in cancer mice, despite a greater increase in Murf1 mRNA in both sexes. CONCLUSIONS: Prior alcohol consumption accelerates or worsens the onset of certain aspects of cancer cachexia in a sex-dependent manner, with males being more sensitive to these exposures, even with abstinence from alcohol prior to tumor initiation.

Mealtime alcohol consumption suppresses skeletal muscle mTORC1 signaling in female mice.

OBJECTIVE: To determine whether alcohol consumed within the meal influences the feeding induced increase in mTORC1 signaling. METHODS: Alcohol provided in the liquid diet was consumed by alcohol naïve, fasted, C57BL/6Hsd female mice and gastrocnemius was collected 1hr after the refeeding. Subsequent experiments determined the extent to which changes in mTORC1 signaling persisted across the day. RESULTS: Compared with control mice, protein synthesis, mTORC1 (Ser2448), 4EBP1 (Ser65), S6K1 (Thr389), rpS6 (Ser240/244), Akt (Thr308), and ULK1 (Ser757) were lower in EtOH. Similar suppressive patterns were observed in the hours following consumption of alcohol containing food throughout the dark cycle. Higher peak blood alcohol concentrations induced by intraperitoneal injection of alcohol extended the time and magnitude of mTORC1 pathway suppression. CONCLUSION: Alcohol administered as part of the meal results in lower skeletal muscle mTORC1 signaling while subsequent models show that alcohol may influence this pathway across the day.

Chronic Alcohol Consumption Disrupts the Skeletal Muscle Circadian Clock in Female Mice.

The intrinsic skeletal muscle core clock has emerged as a key feature of metabolic control and influences several aspects of muscle physiology. Acute alcohol intoxication disrupts the core molecular clock, but whether chronic consumption, like that leading to alcoholic myopathy, is also a zeitgeber for skeletal muscle remains unknown. The purpose of this work was to determine whether chronic alcohol consumption dysregulates the skeletal muscle core molecular clock and clock-controlled genes (CCGs). C57BL/6Hsd female mice (14 weeks old) were fed a control (CON) or alcohol (EtOH) containing liquid diet for 6 weeks. Gastrocnemius muscles and serum were collected from CON and EtOH mice every 4-h for 24-h. Chronic alcohol consumption disrupted genes of the core clock including suppressing the rhythmic peak of expression of Bmal1, Per1, Per2, and Cry2. Genes involved in the regulation of Bmal1 also exhibited lower rhythmic peaks including Reverb α and Myod1. The CCGs, Dbp, Lpl, Hk2, and Hadh were also suppressed by alcohol. The nuclear expression patterns of MYOD1, DBP, and REVERBα were shifted by alcohol, while no change in BMAL1 was detected. Overall, these data indicate that alcohol disrupted the skeletal muscle core clock but whether these changes in the core clock are causative or a consequence of alcoholic myopathy requires future mechanistic confirmation.

Acute binge alcohol alters whole body metabolism and the time-dependent expression of skeletal muscle-specific metabolic markers for multiple days in mice.

Alcohol is a myotoxin that disrupts skeletal muscle function and metabolism, but specific metabolic alternations following a binge and the time course of recovery remain undefined. The purpose of this work was to determine the metabolic response to binge alcohol, the role of corticosterone in this response, and whether nutrient availability mediates the response. Female mice received saline (control) or alcohol (EtOH) (5 g/kg) via intraperitoneal injection at the start of the dark cycle. Whole body metabolism was assessed for 5 days. In a separate cohort, gastrocnemius muscles and liver were collected every 4 h for 48 h following intoxication. Metyrapone was administered before alcohol and gastrocnemius was collected 4 h later. Lastly, alcohol-treated mice were compared with fed or fasted controls. Alcohol disrupted whole body metabolism for multiple days. Alcohol altered the expression of genes and proteins in the gastrocnemius related to the promotion of fat oxidation (Pparα, Pparδ/ß, AMPK, and Cd36) and protein breakdown (Murf1, Klf15, Bcat2). Changes to select metabolic genes in the liver did not parallel those in skeletal muscle. An alcohol-induced increase in circulating corticosterone was responsible for the initial change in protein breakdown factors but not the induction of FoxO1, Cebpß, Pparα, and FoxO3. Alcohol led to a similar, but distinct metabolic response when compared with fasting animals. Overall, these data show that an acute alcohol binge rapidly disrupts macronutrient metabolism including sustained disruption to the metabolic gene signature of skeletal muscle in a manner similar to fasting at some time points.NEW & NOTEWORTHY Herein, we demonstrate that acute alcohol intoxication immediately alters whole body metabolism coinciding with rapid changes in the skeletal muscle macronutrient gene signature for at least 48 h postbinge and that this response diverges from hepatic effects and those of a fasted animal.

High-Fat Diet Augments the Effect of Alcohol on Skeletal Muscle Mitochondrial Dysfunction in Mice.

Previous studies have shown that chronic heavy alcohol consumption and consumption of a high-fat (HF) diet can independently contribute to skeletal muscle oxidative stress and mitochondrial dysfunction, yet the concurrent effect of these risk factors remains unclear. We aimed to assess the effect of alcohol and different dietary compositions on mitochondrial activity and oxidative stress markers. Male and female mice were randomized to an alcohol (EtOH)-free HF diet, a HF + EtOH diet, or a low-Fat (LF) + EtOH diet for 6 weeks. At the end of the study, electron transport chain complex activity and expression as well as antioxidant activity and expression, were measured in skeletal muscles. Complex I and III activity were diminished in muscles of mice fed a HF + EtOH diet relative to the EtOH-free HF diet. Lipid peroxidation was elevated, and antioxidant activity was diminished, in muscles of mice fed a HF + EtOH diet as well. Consumption of a HF diet may exacerbate the negative effects of alcohol on skeletal muscle mitochondrial health and oxidative stress.

Binge alcohol disrupts skeletal muscle core molecular clock independent of glucocorticoids.

Circadian rhythms are central to optimal physiological function, as disruption contributes to the development of several chronic diseases. Alcohol (EtOH) intoxication disrupts circadian rhythms within liver, brain, and intestines, but it is unknown whether alcohol also disrupts components of the core clock in skeletal muscle. Female C57BL/6Hsd mice were randomized to receive either saline (control) or alcohol (EtOH) (5 g/kg) via intraperitoneal injection at the start of the dark cycle [Zeitgeber time (ZT12)], and gastrocnemius was collected every 4 h from control and EtOH-treated mice for the next 48 h following isoflurane anesthetization. In addition, metyrapone was administered before alcohol intoxication in separate mice to determine whether the alcohol-induced increase in serum corticosterone contributed to circadian gene regulation. Finally, synchronized C2C12 myotubes were treated with alcohol (100 mM) to assess the influence of centrally or peripherally mediated effects of alcohol on the muscle clock. Alcohol significantly disrupted mRNA expression of Bmal1, Per1/2, and Cry1/2 in addition to perturbing the circadian pattern of clock-controlled genes, Myod1, Dbp, Tef, and Bhlhe40 (P < 0.05), in muscle. Alcohol increased serum corticosterone levels and glucocorticoid target gene, Redd1, in muscle. Metyrapone prevented the EtOH-mediated increase in serum corticosterone but did not normalize the EtOH-induced change in Per1, Cry1 and Cry2, and Myod1 mRNA expression. Core clock gene expression (Bmal, Per1/2, and Cry1/2) was not changed following 4, 8, or 12 h of alcohol treatment on synchronized C2C12 myotubes. Therefore, binge alcohol disrupted genes of the core molecular clock independently of elevated serum corticosterone or direct effects of EtOH on the muscle.NEW & NOTEWORTHY Alcohol is a myotoxin that impairs skeletal muscle metabolism and function following either chronic consumption or acute binge drinking; however, mechanisms underlying alcohol-related myotoxicity have not been fully elucidated. Herein, we demonstrate that alcohol acutely interrupts oscillation of skeletal muscle core clock genes, and this is neither a direct effect of ethanol on the skeletal muscle, nor an effect of elevated serum corticosterone, a major clock regulator.

Effects of alcohol on skeletal muscle contractile performance in male and female mice.

BACKGROUND: Acute and chronic alcohol use can cause skeletal muscle myopathy in concert with impairments in skeletal muscle strength, function and fatigue resistance. However, the fundamental contractile deficits induced in the presence of alcohol versus those observed in the recovery period following the clearance of alcohol have not yet been characterized nor is it known whether sex influences these outcomes. METHODS: Male and female mice received an intraperitoneal injection of either saline (Control) or ethanol (EtOH; 5g/kg body weight). Muscle force, fatigue, fatigue recovery and twitch characteristics of the posterior crural muscle complex were measured in situ 1 hour and 24 hours post alcohol. RESULTS: In the presence of alcohol (1-hour post treatment) absolute and normalized force generated at 80-150 Hertz was decreased in male and female mice with concurrent reductions in the rate of force development and increases in ½ relaxation time. When expressed as a percentage of maximum force, both males and females also displayed an alcohol-induced leftward shift in the force frequency curve indicative of a type I contractile phenotype. Alcohol enhanced fatigue in both males and females but had no effect on force recovery. Following clearance of alcohol (24-hour post treatment), contractile function was completely restored in females while alcohol treated males experienced sustained reductions in absolute force and had enhanced fatigue compared with male controls. CONCLUSIONS: In the presence of alcohol, both males and females exhibited significant declines in muscle force production and enhanced fatigue; however, following complete clearance of the alcohol, females recovered all functional parameters, while males did not.

Tumor necrosis factor-α, TNF receptor, and soluble TNF receptor responses to aerobic exercise in the heat.

The purpose of this study was to evaluate the effects of aerobic exercise in the heat on circulating concentrations of tumor necrosis factor (TNF)-α, soluble TNF receptors (STNFR1&2), and surface expression of TNFR1&2 on monocyte subpopulations. Twelve recreationally active Caucasian men (24.4 ± 3.4 yrs.; 180.0 ± 6.8 cm; 81.5 ± 8.0 kg; 47.2 ± 4.8 mL·kg-1·min-1) completed an exercise protocol in three environmental conditions: high temperature/low humidity [HTLH; 35 °C, 20% relative humidity (RH)]; high temperature/moderate humidity (HTMH; 35 °C, 45%RH); and moderate temperature/moderate humidity (MTMH; 22 °C, 45%RH). Each protocol consisted of a 60-minute cycling trial at 60% VO2max, a 15-minute rest, and a time-to-exhaustion trial at 90% VO2max (TTE). Blood was sampled before (PRE), immediately after (POST) the 60-minute trial, immediately post-TTE (PTTE), and one-hour post-TTE (REC). Circulating TNF-α and STNFR1&2 were assayed. TNFR1&2 expression on monocyte subsets was measured by flow cytometry on a subset of participants (n = 8). TNF-α area under the curve with respect to increase (AUCi) was greater during HTMH compared to MTMH and HTLH. STNFR1 concentration was greater during HTMH compared to MTMH. With all trials combined, STNFR1 concentration increased from PRE to POST, PTTE, and REC. TNFR1 expression on non-classical monocytes was greater during HTMH compared to HTLH while TNFR2 expression was lower during HTLH compared to both MTMH and HTMH. Data suggest that exercise in the heat increases circulating TNF-α and STNFR1 concentration concomitantly. Furthermore, non-classical monocyte expression of TNFRs are impacted by temperature and humidity during exercise.