Effects Of Skeletal Muscle ER/SR Stress Chaperones Expression During Exercise, Diet Restriction In Rats

Purpose:ER/SR Stress is one phenomenon of cell metabolic disturbance, over-expression of ER/SR Stress can even cause apoptosis.On another hand, expression of ER/SR Stress in a certain extent is a mechanism in cell protection.Exercise can elevate concentration of Ca2+ and evoke the deficiency of carbohydrate,and these factors induce the ER/SR stress. The same changes also happened when organism is limited for the food intake,and this can also cause ER/SR stress.This study discusses Effects of ER/SR Stress Chaperones Expression during Exercise,Diet Restriction and Carbohydrate/ Peptide Supplement based on glycometabolic in integrated and molecular level.Methods:86 Sprague-Dawley rats were randomly placed in non-training control group(NC),non-training+diet restriction group(NDR),training control group(TC),training+diet restriction group(TDR),training+pre-CHO-supplying group(TPG), training+pre-CHO and peptide-supplying group(TPGP),training+post-CHO -supplying group(TPOG),training+post-CHO and peptide-supplying group(TPOGP).The training protocol used in the study is a 4 wk endurance swimming train and the intensity is controlled by increasing the load progressively.The rats in TPG and TPOG groups are supplied with liquid carbohydrate 1.2g/kg body weight per day.The rats in TPGP and TPOGP groups are supplied with liquid peptide 0.3g/kg body weight per day+ liquid carbohydrate 1.2g/kg body weight per day.After the protocol,we detect the ER/SR stress chaperones GRP78 and ORP150's expression by RT-PCR and Western Blotting;measure the body weight of rats;determine the levels of blood glucose,serum insulin and plasma glucagons;detect Pyruvate Kinase(PK) and Hexokinase(HK) activities,glycogen reserve in rats' quadriceps femoris after the training.Results:â‘ during the training,ER/SR stress chaperones GRP78 and ORP150's expression are up-regulated lightly.The level of blood glucose and serum insulin are declined,HK activity is increased.The adaption of ER/SR stress is a channel to increase the capacity of organism,but overstress for a long time can disturb the homeostasis,evoking apoptosis which is mediated by ER/SR stress.This might be an important mechanism of periphery fatigue in exercise performance;â‘¡after 70%diet restriction for 4wk,there are no significant changes on the expression of ER/SR stress chaperones GRP78 and ORP150;the decline of body weight,levels of blood glucose and serum insulin which evoked by diet restriction might be a result of organism safety.â‘¢supplying carbohydrate+peptide reasonably can increase the tendency of ER/SR stress chaperones GRP78's expression. This supply may play a possible role in replenishing energy,facilitating the uptake of carbohydrate by skeletal muscle to synthesis glycogen and to reduce the impairment of stress.Conclusion:the training protocol and/or 70%diet restriction can evoke changes in rats' growth and carbohydrate glycometabolic,and up-regulate chaperones GRP78 and ORP150's expression with skeletal muscle ER/SR stress.When exercise and diet restriction play together,some index's changes are more markedly.Supply carbohydrate and peptide might play a possible role of up-regulating the expression of GRP78 and ORP150mRNA.The up-regulation facilitates adaption of ER/SR stress in organism.It is not only a channel to improve the capacity,but also a protection mechanism to organism. The changes of glycometabolic and it's hormone level may be a result of organism safety.