Eddie Vedder
2011-09-14, 10:22
Abstract
This study was designed to determine whether sprint exercise activates signaling cascades linked to leptin actions in human skeletal muscle and how this pattern of activation may be interfered by glucose ingestion. Muscle biopsies were obtained in 15 young healthy men in response to a 30-s sprint exercise (Wingate test) randomly distributed into two groups: the fasting (n = 7, C) and the glucose group (n = 8, G), who ingested 75 g of glucose 1 h before the Wingate test. Exercise elicited different patterns of JAK2, STAT3, STAT5, ERK1/2, p38 MAPK phosphorylation, and SOCS3 protein expression during the recovery period after glucose ingestion. Thirty minutes after the control sprint, STAT3 and ERK1/2 phosphorylation levels were augmented (both, P < 0.05). SOCS3 protein expression was increased 120 min after the control sprint but PTP1B protein expression was unaffected. Thirty and 120 min after the control sprint, STAT5 phosphorylation was augmented (P < 0.05). Glucose abolished the 30 min STAT3 and ERK1/2 phosphorylation and the 120 min SOCS3 protein expression increase while retarding the STAT5 phosphorylation response to sprint. Activation of these signaling cascades occurred despite a reduction of circulating leptin concentration after the sprint. Basal JAK2 and p38 MAPK phosphorylation levels were reduced and increased (both P < 0.05), respectively, by glucose ingestion prior to exercise. During recovery, JAK2 phosphorylation was unchanged and p38 MAPK phosphorylation was transiently reduced when the exercise was preceded by glucose ingestion. In conclusion, sprint exercise performed under fasting conditions is a leptin signaling mimetic in human skeletal muscle.
http://jap.physiology.org/content/111/3/715.full
Is sprint exercise a leptin signaling mimetic in human skeletal muscle? J Appl Physiol. 2011 Sep;111(3):715-25. Epub 2011 Jun 9.
In agreement with our hypothesis, glucose ingestion, likely through the sustained elevation of insulin, blunted the exercise-induced STAT3 and ERK phosphorylation observed at 30 min post-sprint in the control condition and retarded STAT5 phosphorylation. Likewise, the elevation of SOCS3 protein expression observed 120 min after the fasting Wingate was also blunted when the sprint was preceded by the ingestion of glucose. These changes in signaling occurred with minimal changes in circulating leptin and IL-6 concentrations. Altogether, these results indicate that sprint exercise performed under fasting conditions elicits signaling events similar to those described in rodent skeletal muscle after leptin injections, i.e., sprint exercise under fasting conditions acts as a leptin signaling mimetic in human skeletal muscle. However, glucose ingestion prior to the sprint exercise blunts this effect.
[...]
In conclusion, this study shows that most of the signaling pathways activated by leptin in rodent skeletal muscle are also activated by sprint exercise in human skeletal muscle, despite a small reduction of leptin serum concentration after the sprint exercise. These findings imply that sprint exercise behave as a leptin mimetic and could be used to stimulate the leptin signaling pathways in human skeletal muscle. This opens the possibility of using sprint exercise to circumvent leptin resistance in obese humans and may lead to increased leptin sensitivity. We provide some evidence to support that the effects of sprint exercise on ERK, STAT3, STAT5, and SOCS3 are not mediated by changes in either serum leptin or IL-6 concentrations, while the expression of SOCS3 and the phosphorylation of STAT5 may have been induced by GH. Importantly, we showed that glucose ingestion 1 h prior to the sprint exercise abolishes or delays some of the exercise-elicited signaling responses, implying that the adaptative responses to sprint exercise training may be modulated by the postabsorptive state.
This study was designed to determine whether sprint exercise activates signaling cascades linked to leptin actions in human skeletal muscle and how this pattern of activation may be interfered by glucose ingestion. Muscle biopsies were obtained in 15 young healthy men in response to a 30-s sprint exercise (Wingate test) randomly distributed into two groups: the fasting (n = 7, C) and the glucose group (n = 8, G), who ingested 75 g of glucose 1 h before the Wingate test. Exercise elicited different patterns of JAK2, STAT3, STAT5, ERK1/2, p38 MAPK phosphorylation, and SOCS3 protein expression during the recovery period after glucose ingestion. Thirty minutes after the control sprint, STAT3 and ERK1/2 phosphorylation levels were augmented (both, P < 0.05). SOCS3 protein expression was increased 120 min after the control sprint but PTP1B protein expression was unaffected. Thirty and 120 min after the control sprint, STAT5 phosphorylation was augmented (P < 0.05). Glucose abolished the 30 min STAT3 and ERK1/2 phosphorylation and the 120 min SOCS3 protein expression increase while retarding the STAT5 phosphorylation response to sprint. Activation of these signaling cascades occurred despite a reduction of circulating leptin concentration after the sprint. Basal JAK2 and p38 MAPK phosphorylation levels were reduced and increased (both P < 0.05), respectively, by glucose ingestion prior to exercise. During recovery, JAK2 phosphorylation was unchanged and p38 MAPK phosphorylation was transiently reduced when the exercise was preceded by glucose ingestion. In conclusion, sprint exercise performed under fasting conditions is a leptin signaling mimetic in human skeletal muscle.
http://jap.physiology.org/content/111/3/715.full
Is sprint exercise a leptin signaling mimetic in human skeletal muscle? J Appl Physiol. 2011 Sep;111(3):715-25. Epub 2011 Jun 9.
In agreement with our hypothesis, glucose ingestion, likely through the sustained elevation of insulin, blunted the exercise-induced STAT3 and ERK phosphorylation observed at 30 min post-sprint in the control condition and retarded STAT5 phosphorylation. Likewise, the elevation of SOCS3 protein expression observed 120 min after the fasting Wingate was also blunted when the sprint was preceded by the ingestion of glucose. These changes in signaling occurred with minimal changes in circulating leptin and IL-6 concentrations. Altogether, these results indicate that sprint exercise performed under fasting conditions elicits signaling events similar to those described in rodent skeletal muscle after leptin injections, i.e., sprint exercise under fasting conditions acts as a leptin signaling mimetic in human skeletal muscle. However, glucose ingestion prior to the sprint exercise blunts this effect.
[...]
In conclusion, this study shows that most of the signaling pathways activated by leptin in rodent skeletal muscle are also activated by sprint exercise in human skeletal muscle, despite a small reduction of leptin serum concentration after the sprint exercise. These findings imply that sprint exercise behave as a leptin mimetic and could be used to stimulate the leptin signaling pathways in human skeletal muscle. This opens the possibility of using sprint exercise to circumvent leptin resistance in obese humans and may lead to increased leptin sensitivity. We provide some evidence to support that the effects of sprint exercise on ERK, STAT3, STAT5, and SOCS3 are not mediated by changes in either serum leptin or IL-6 concentrations, while the expression of SOCS3 and the phosphorylation of STAT5 may have been induced by GH. Importantly, we showed that glucose ingestion 1 h prior to the sprint exercise abolishes or delays some of the exercise-elicited signaling responses, implying that the adaptative responses to sprint exercise training may be modulated by the postabsorptive state.