Aerobic Training in Rats Increases Skeletal Muscle Sphingomyelinase and Serine Palmitoyltransferase Activity, While Decreasing Ceramidase Activity

Abstract

Sphingolipids are important components of cell membranes that may also serve as cell signaling molecules; ceramide plays a central role in sphingolipid metabolism. The aim of this study was to examine the effect of 5 weeks of aerobic training on key enzymes and intermediates of ceramide metabolism in skeletal muscles. The experiments were carried out on rats divided into two groups: (1) sedentary and (2) trained for 5 weeks (on a treadmill). The activity of serine palmitoyltransferase (SPT), neutral and acid sphingomyelinase (nSMase and aSMase), neutral and alkaline ceramidases (nCDase and alCDase) and the content of sphingolipids was determined in three types of skeletal muscle. We also measured the fasting plasma insulin and glucose concentration for calculating HOMA-IR (homeostasis model assessment) for estimating insulin resistance. We found that the activities of aSMase and SPT increase in muscle in the trained group. These changes were followed by elevation in the content of sphinganine. The activities of both isoforms of ceramidase were reduced in muscle in the trained group. Although the activities of SPT and SMases increased and the activity of CDases decreased, the ceramide content did not change in any of the studied muscle. Although ceramide level did not change, we noticed increased insulin sensitivity in trained animals. It is concluded that training affects the activity of key enzymes of ceramide metabolism but also activates other metabolic pathways which affect ceramide metabolism in skeletal muscles.

Muscle sphingolipids during rest and exercise: a C18:0 signature for insulin resistance in humans

“…Chronic endurance training decreases muscle ceramide content in rodents [41] and humans [10][11][12] [42]. Additionally, endurance training decreased the C18:0 sphingomyelin content of human muscle, which may help explain the lower C18:0 ceramide levels in athletes in this study [14].…”

Preservation of Metabolic Flexibility in Skeletal Muscle by a Combined Use of n-3 PUFA and Rosiglitazone in Dietary Obese Mice

“…Moreover, the involvement of ceramide-derived sphingosines in the activation of AMP-activated protein kinase by adiponectin, downstream from the adiponectin receptors, was recently suggested [67]. This mechanism, which should operate in the muscle, suggests a new role for the sphingolipid metabolism [66] with respect to its long-disputed role in affecting muscle insulin sensitivity [65], [66], [68]–[70]. Our results further support the importance of SM(OH) C24∶1 as a marker of the muscle sphingosines metabolism.…”

Involvement of sphingosine 1-phosphate in palmitate-induced insulin resistance of hepatocytes via the S1P2 receptor subtype

“…Moreover, it has been shown that key enzymes of ceramide metabolism in rat muscles are modulated in response to physical activity. This is accompanied by an increased insulin sensitivity, suggesting a crucial role of sphingolipids in skeletal glucose homeostasis [35].…”