The role of rock protein on glucose uptake in the skeletal muscle of exercised rodents during aging process

Author(s)

Vitor Rosetto Muñoz

• Document type: Master's Dissertation
• Press: Limeira, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Aplicadas
• Defense date: 2018-08-28

Examining board members

José Rodrigo Pauli; Fernando Moreira Simabuco; Licio Augusto Velloso

• Advisor: Leandro Pereira de Moura; José Rodrigo Pauli

Abstract

The aging process is associated with different metabolic disorders, including the insulin resistance (IR). The physical exercise presents an important non-pharmacological role in the IR treatment and associated health complications. The Rho-kinase (Rock) protein is proposed as an important molecule involved in the IRS1 phosphorylation contributing with ~50% of the skeletal muscle glucose uptake in the skeletal muscle. Thus, the aim of this study was to evaluate the role of physical exercise in the Rock activity and insulin-signaling pathway in young, middle-aged and aged rats. Firstly, the role of Rock protein was confirmed in C2C12 myotube cells through Rock inhibition (Y-27632) and insulin-signaling pathway evaluation. Then, Fischer 344 and Wistar rats were distributed in three groups: Young Sedentary (5 months), Middle-aged (17 months), and Aged (26 months). The middle-aged groups were submitted to swimming physical training protocol during 7 days, composed by 4 sessions of 30 minutes swimming separated by 10 minutes of rest. After the first session, it was utilized the load of 1,5% of the body weight in the last three sessions. The aged animals were submitted to treadmill physical training protocol during 5 days, composed by 2 sessions of 30 minutes separated by 10 minutes. The animals were submitted to insulin tolerance test and glucose tolerance test. Sixteen hours after the physical exercise the animals were euthanized to evaluate the insulin-signaling pathway and proteins involved with Rock metabolism through immunoprecipitation, immunoblot and Rock activity assay in the skeletal muscle and white adipose tissue. In the results, middle-aged Fischer and Wistar demonstrated impairments in the Rock metabolism and insulin-signaling pathway in the skeletal muscle; however, only middle-aged Wistar rats presented increased Rock content in the white adipose tissue (where this protein shows a negative role), and an insulin resistant state. In the next step, we found the role of physical exercise to increase the Rock activity in young rats, and increase the phosphorylation in proteins involved with insulin pathway, also increasing the GLUT4 translocation to plasmatic membrane. Otherwise, the inhibition of Rock activity (Y-27632), suppressed the effect from the physical exercise to improve the insulin sensitivity and the insulin-signaling pathway to increase the glucose uptake in the skeletal muscle. Finally, both in the middle-aged and aged Fischer rats, it was not found great impairments related to Rock metabolism and insulin-signaling pathway in the soleus muscle; however, the physical exercise was able to increase Rock2 content and phosphorylation of insulin-signaling pathway proteins. In summary, the Rock protein seems to show an important participation in the insulin sensitivity improvement after the physical exercise, also, the activity of this protein is impaired in the middle-aged condition, and the physical exercise is one effective intervention to improve its activity in the skeletal muscle, and consequently contributing to the glucose homeostasis in Wistar and Fischer 344 rats (AU)

• FAPESP's process: 15/26000-2 - The role of Rock protein on glucose uptake in the skeletal muscle of exercised rodents during the aging process
• Grantee: Vitor Rosetto Muñoz
• Support Opportunities: Scholarships in Brazil - Master