Proteomic investigation of the acute and chronic changes in rat skeletal muscle in reseponse to endurence exercise

Author(s)

Paulo Guimarães Gandra

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2010-04-30

Examining board members

Denise Vaz de Macedo; Richard Hemmi Valente; Claudio Cesar Zoppi; Maria Alice Rostom de Mello; Claudio Alexandre Gobatto

• Advisor: Denise Vaz de Macedo

Abstract

In the present work the acute and chronic changes in rat skeletal muscle in response to endurance exercise were investigated by proteomic analysis. The results are presented in two separated studies. In the first study gastrocnemius muscle were sampled from control non exercised animals and from animals exercised to exhaustion in an incremental manner in a treadmill. Exercised rats were sacrificed 3 and 24h after exercise cessation. We used the classic proteomic approach which utilizes two dimensional electrophoresis (2DE) to separate the proteins and mass spectrometry to identify these proteins. Six spots presented significant alterations in their relative volume. Spots identified as GAPDH, triose phosphate isomerase 1, beta subunit of pyruvate dehydrogenase E1, carnitine palmitoil transferase 2 and HSC70 were up-regulated after exercise. The spot identified as ?-actin was down-regulated after exercise. This results suggests that one bout of endurance exercise in untrained muscle may stimulate sarcoplasmic and mitochondrial proteins synthesis but not myofibril proteins. Proteins presenting increased abundance after one single bout of endurance exercise may be important for the preconditioning of skeletal muscle for a subsequent exercise bout. In the second study we present the proteomic analysis of the red (RG) and white portion (WG) of gastrocnemius muscle sampled from rats well adapted to endurance exercise (T1), well trained and submitted to an overtraining period (T2) and from control non exercised rats (C). Rats from group T2 were also subdivided in a functional overreaching group (FOR) which is composed by rats demonstrating an enhanced or unchanged performance after the overtraining period or a non functional overreaching group (NFOR) which is composed by rats demonstrating decreased performance levels after the overtraining period. When comparing C, T1 and T2, 32 spots demonstrated altered abundance in RG and 22 in the WG. The main alterations in RG were observed in the T2 group and indicated increased mitochondrial biogenesis, increased capacity of lipid uptake, antioxidant capacity, chaperone function, and a shift of fiber type from a fast-glycolytic to a slow-oxidative pattern. All these changes demonstrated the efficiency of an intensified training period to adapt skeletal muscle. The expected adaptations to endurance training were not evident in WG and the results such as decreased aconitase spots volume suggest higher oxidative stress levels in WG than in RG during overtraining. Myofilament and myofilament interacting proteins abundance were altered after chronic endurance stimuli. The results presented here suggests that the initial response of skeletal muscle to one single bout of endurance exercise encompasses an nonspecific increase of ATP production capacity while chronic stimulation increases only the oxidative capacity with a concomitant decrease in glycolytic proteins abundance. Also the results draw attention to the roles of mitochondria and myofilament proteins in adaptation and maladaptation to endurance exercise. (AU)