Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC204
Effect of exercise induced Stress on leukocyte Hsp72, GRP78, Hsp90α and GRP94 mRNA expression.
J. Tuttle1,2, L. Taylor1,2, M. Lewis1,2, P. Castle1,2
1. Muscle Cellular and Molecular Physiology Research Group, ISPAR, University of Bedfordshire, Bedford, Bedfordshire, United Kingdom. 2. Applied Sport and Exercise Physiology Research Group, ISPAR, University of Bedfordshire, Bedford, Bedfordshire, United Kingdom.
Heat shock proteins (HSPs) are a group of proteins which are ubiquitously expressed within leukocytes and which have a key function in maintaining leukocyte homeostasis and function during both the immune and inflammatory responses to exercise. They function to prevent a loss of protein activity caused by various physiological stressors such as exercise, heat and oxidative stress (Noble et al, 2008). Exercise induced upregulation of basal Hsp content may provide enhanced protection against future stressors (Paulsen et al, 2009), however there is little information regarding the effect of mechanical stress (exercise induced muscle damage) and heat stress on expression across the whole range of Hsps. The aim of this study was therefore to determine whether metabolic stress, mechanical stress, heat stress or heat plus mechanical stress altered leukocyte hsp gene expression. With university ethical approval 14 physically active students (mean ± SD; age 19.86±2.53 y, body mass 71.33±8.66 kg, VO2max 55.49±5.94 ml.kg-1.min-1) participated. Using an independent groups design, participants were randomly allocated to either a temperate (20°C, 50% RH) or heat group (30°C, 50% RH). In a random order participants in the temperate group completed 30 min running (1% gradient) at lactate threshold (LT; metabolic stress/control condition) and 30 min downhill running (-10% gradient) at LT (mechanical stress). Participants in the heat group completed the same protocols in the heat (heat stress and heat plus mechanical stress). Core temperature, oxygen consumption, heart rate and subjective RPE & ratings of thermal sensation (TS) were measured continuously during exercise. Venous whole blood samples were obtained for determination of HSP gene expression along with measurements of muscle soreness (pressure sensitivity and subjective ratings) immediately before, immediately after, 3hrs after and 24 hrs after exercise. Leukocytes were isolated using an erythrocyte lysis solution, RNA was extracted via the Trizol method and gene expression was determined using Quantitative RT-PCR. Initial statistical analysis was conducted using a factorial ANOVA. Initial results below equate to N=5. Heat & mechanical stress induced a significant (380.4±112.89% Vs 152± 43.84% P <0.05) increase in hsp72 gene expression and a non significant increase in GRP78 (224.6±106.7% Vs 121.43±18.03%) hsp90α (359.6±230.72% Vs 121.83±16.13%) and GRP94 gene expression (393.4.6±214% Vs 118.2±75.5%) compared to metabolic stress. Core Temperature was significantly elevated in Heat & mechanical stress (39.2±0.2°C) compared to metabolic stress (38.3±0.3°C) suggesting that an elevated core temperature may have contributed to the increase in hsp gene expression.
Where applicable, experiments conform with Society ethical requirements