Exercise-induced lactate accumulation regulates intramuscular triglyceride metabolism via transforming growth factor-β1 mediated pathways

The mechanism regulating the utilization of intramuscular triacylglycerol (IMTG) during high-intensity interval training (HIIT) and post-exercise recovery period remains elusive. In this study, the acute and long-term effects of HIIT on transforming growth factor beta 1 (TGF-β1) abundance in rat skeletal muscle and role of lactate and TGF-β1 in IMTG lipolysis during post-exercise recovery period were examined. TGF-β1 and Adipose triacylglycerol lipase (ATGL) abundance as well as total lipase activity in the gastrocnemius muscle significantly increased to a maximum value 10 h after acute bout of HIIT. Inhibition of TGF-β1 signaling by intramuscular injection of SB431542 30 min prior to the acute exercise attenuated ATGL abundance and total lipase activity in the gastrocnemius muscle in response to acute exercise. Intramuscular acute injection of lactate increased TGF-β1 and ATGL abundance in the gastrocnemius muscle and there were a significant increase in Muscle TGF-β1 and ATGL abundance after 5 weeks of HIIT/lactate treatment. These results indicate that exercise-induced lactate accumulation regulates intramuscular triglyceride metabolism via transforming growth factor-β1 mediated pathways during post-exercise recovery from strenuous exercise

Lactate Transporters Expression in Tumor of Balb/c Mice Bearing Breast Cancer after Endurance Training

Background & aim: Changes in the metabolism of cancer cells plays a major role in the survival and their expansion. The aim of this study was to determine expression of lactate transmitters in Balb/c mice with breast cancer after endurance training. Methods: In this experimental study twenty-five Balb C mice were randomly divided into two groups of breast cancer control (N=13) and breast cancer training (N=12). Breast cancer was induced in mammary fat pad by injection of cancer cells (MC4L2) in mice and endurance training protocol was applied for 7 weeks in the experimental group. Tumor volume and MCT1, MCT4, and CD147 expression were measured by micro digital caliper and western blotting technique respectively. Data were analyzed statistically using Student t and Pearson. Results: Significant decreases was found in weight and CD147 expression of tumor after 7 weeks of endurance training in the exercise group compared to the control group. No significant differences were seen in MCT4 expression and tumor volume between the groups (05 / 0p>0.05). Significant correlation was found between tumor MCT1 and CD147 expression (P < 0.05), while the relationship between MCT4 and CD147 expression in tumors was not statistically significant. Conclusion: Endurance training can reduce lactate metabolism in cancer cells through suppression of lactate transporters expression and provides a useful tool in breast cancer treatment or prevention

Lactate regulates autophagy through ROS-mediated activation of ERK1/2/m-TOR/p-70S6K pathway in skeletal muscle

The role of autophagy and lysosomal degradation pathway in the regulation of skeletal muscle metabolism was previously studied. However, underlying molecular mechanisms are poorly understood. L-lactate which is utilized as an energetic substrate by skeletal muscle can also augment genes expression related to metabolism and up-regulate those being responsive to reactive oxygen species (ROS). Since ROS is the most important regulator of autophagy in skeletal muscle, we tested if there is a link between cellular lactate metabolism and autophagy in differentiated C2C12 myotubes and the gastrocnemius muscle of male wistar rats. C2C12 mouse skeletal muscle was exposed to 2, 6, 10, and 20 mM lactate and evaluated for lactate autophagic effects. Lactate dose-dependently increased autophagy and augmented ROS generation in differentiated C2C12 myotubes. The autophagic effect of lactate deterred in N-acetylcysteine presence (NAC, a ROS scavenger) indicated lactate regulates autophagy with ROS participation. Lactate-induced up-regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) through ROS was required to regulate the autophagy by lactate. Further analysis about ERK1/2 up- and downstream indicated that lactate regulates autophagy through ROS-mediated the activation of ERK1/2/mTOR/p70S6K pathway in skeletal muscle. The in vitro effects of lactate on autophagy also occurred in the gastrocnemius muscle of male Wistar rats. In conclusion, we provided the lactate-associated regulation evidence of autophagy in skeletal muscle by activating ROS-mediated ERK1/2/mTOR/p70S6K pathway. Since the increase in cellular lactate concentration is a hallmark of energy deficiency, the results provide insight into a skeletal muscle mechanism to fulfill its enhanced energy requirement. © 2021, The International CCN Society

Resistance training-induced muscle hypertrophy is mediated by TGF-β1-Smad signaling pathway in male Wistar rats

The TGF-β1-Smad pathway is a well-known negative regulator of muscle growth; however, its potential role in resistance training-induced muscle hypertrophy is not clear. The present study proposed to determine whether and how this pathway may be involved in resistance training-induced muscle hypertrophy. Skeletal muscle samples were collected from the control, trained (RT), control + SB431542 (CITGF), and trained + SB431542 (RTITGF) animals following 3, 5, and 8 weeks of resistance training. Inhibition of the TGF-β1-Smad pathway by SB431542 augmented muscle satellite cells activation, upregulated Akt/mTOR/S6K1 pathway, and attenuated FOXO1 and FOXO3a expression in the CITGF group (all p &lt;.01), thereby causing significant muscle hypertrophy in animals from the CITGF. Resistance training significantly decreased muscle TGF-β1 expression and Smad3 (P-Smad3S423/425) phosphorylation at COOH-terminal residues, augmented Smad2 (P-Smad2-LS245/250/255) and Smad3 (P-Smad3-LSer208) phosphorylation levels at linker sites (all p &lt;.01), and led to a muscle hypertrophy which was unaffected by SB431542, suggesting that the TGF-β1-Smad signaling pathway is involved in resistance training-induced muscle hypertrophy. The effects of inhibiting the TGF-β1-Smad signaling pathway were not additive to the resistance training effects on FOXO1 and FOXO3a expression, muscle satellite cells activation, and the Akt/mTOR/S6K1 pathway. Resistance training effect of satellite cell differentiation was independent of the TGF-β1-Smad signaling pathway. These results suggested that the effect of the TGF-β1-Smad signaling pathway on resistance training-induced muscle hypertrophy can be attributed mainly to its diminished inhibitory effects on satellite cell activation and protein synthesis. Suppressed P-Smad3S423/425 and enhanced P-Smad2-LS245/250/255 and P-Smad3-LSer208 are the molecular mechanisms that link the TGF-β1-Smad signaling pathway to resistance training-induced muscle hypertrophy. © 2020 Wiley Periodicals, Inc

Antiretroviral therapy adherence and its determinant factors among people living with HIV/AIDS: A case study in Iran

Abstract Objectives This descriptive-correlational study was conducted on 122 Iranian people living with HIV (PWHIV), who referred to a behavioral diseases counseling center in 2018. The AIDS Clinical Trial Group (ACTG) questionnaire was used to collect the required data. The study aimed to determine the level of medication adherence and its determinants in PWHIV. Results About 75.4% (confidence interval 67.2%–82.8%) of the samples had a good combined antiretroviral therapy (cART) adherence and 74.6% (n = 91) of them were sure about the positive effects of medications on their health. Patients reported that most important reasons for medication non-adherence included forgetfulness, high drug dosage, lack of knowledge about ART value, and transportation problems