Effects of exercise on expression and phosphorylation of PI3K and PKB in insulin signaling in the skeletal muscles of type 2 diabetic rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of exercise on the expressions of phosphatidylinositol 3 kinase (PI3K) and protein kinase B (PKB) phosphorylation, protein and glucose transport proteins (GLUT4) at both the protein and mRNA levels in the skeletal muscles of type 2 diabetic rats.</p><p><b>METHODS</b>Thirty male SD rats were randomly divided into control group with normal diet feeding, diabetic group and diabetic exercise group with high-fat diet feeding. After 8 weeks of the high-fat diet, each rat received an intraperitoneal injection of streptozotocin (STZ, 30 mg/kg). Three weeks after the injection, the rats were rated for the presence of diabetes, and the rats in the exercise groups took swimming training for 4 weeks; all the groups maintained their assigned diets. The gastrocnemius of all the rats were dissected 48 h after the last training session. Western blotting was applied to detect the phosphorylation and protein expression of PI3K and PKB and the protein expression of GLUT4. The expression of GLUT4 mRNA was determined by RT-PCR.</p><p><b>RESULTS</b>Compared with the diabetic group, the diabetic rats in the exercise group showed significantly increased protein expression and phosphorylation of PKB (P<0.05) and elevated GLUT4 protein and mRNA expressions in the skeletal muscles (P<0.01, P<0.05).</p><p><b>CONCLUSION</b>Exercise training can modulates insulin signal transduction through the protein expression and phosphorylation of the protein kinase to promote glucose uptake in the skeletal muscle of type 2 diabetic rats.</p>

Effects of exercise on JNK phosphorylation and expression in skeletal muscle of rats / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of exercise on JNK phosphorylation, protein and gene expression.</p><p><b>METHODS</b>Male rats were randomly divided into control and trained groups. The trained rats were submitted to 1 h or 1.5 h of exercise daily and had a fragment of their excised gastrocenemius muscle, 24 h or 48 h after the last training session. The train lasted for 7 weeks. The changes in the expressions of JNK and p-JNK were determined by Western blotting. The expression of JNK mRNA was determined by RT-PCR.</p><p><b>RESULTS</b>Glucose tolerance test found that blood insulin concentration was decreased with exercise training. Exercise led to a marked increase in p-JNK of trained groups 24 hours after exercise in rats that exercised for 1 hour per day and 24 and 48 hours after the exercise in those that exercised for 1.5 hours per day as compared with controls, and the protein expression of JNK significantly increased 24 and 48 hours after the exercise in rats that exercised for 1.5 hours per day. JNK mRNA was increased by exercise 1.5 h/d, 24 h after the last training session.</p><p><b>CONCLUSION</b>Exercise could increase muscle responsiveness to insulin, improving the total JNK and p-JNK and mRNA expression.</p>

Effect of lead on ERK activity and the protective function of bFGF in rat primary culture astroglia / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

<p><b>OBJECTIVE</b>To observe the effects of lead on levels of phosphorylated extracellular signal regulated kinase (p-ERK) in the cytoplasm of primary cultures of rat astroglial cells and the possible protective effect of basic fibroblast growth factor (bFGF) on lead-induced effects.</p><p><b>METHODS</b>The primary astroglia cells from 1~6 d old Wistar rats were cultured. The cells pretreated with the MEK1 (mitogen-activated protein kinase kinase 1) inhibitor PD98059 and bFGF, respectively, were exposed to Pb acetate of different concentrations for different times. Western blotting and reverse transcription polymerase chain reaction (RT-PCR) methods were used to detect the protein and mRNA expressions of ERK.</p><p><b>RESULTS</b>mRNA expression for ERK peaked 15 min after initiation of lead exposure (P<0.05) and protein expression of p-ERK peaked at 30 min (P<0.05). ERK mRNA levels and p-ERK protein levels returned to baseline after 60 and 120 min of lead exposure, respectively (P>0.05). The increase in p-ERK levels in lead-treated cells could be inhibited by PD098059. Activation of ERK in the cells by lead was prevented by pretreatment with bFGF. Total ERK protein levels did not change under the same experimental conditions (P>0.05).</p><p><b>CONCLUSION</b>Low-level lead exposure resulted in transient activation of ERK through the MEK pathway, which then returned to basal levels in the continued presence of lead. Exogenous bFGF protected ERK signaling components in astroglia from lead poisoning.</p>

Effects of endurance exercise on ERK1/2 phosphorylation and expression in skeletal muscle of rats / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of exercise on phosphorylated and total ERK1/2, and mRNA of ERK2.</p><p><b>METHODS</b>Male rats were randomly divided into control and trained groups. The trained rats were submitted to 1 h or 1.5 h of exercise daily and had a fragment of their excised gastroenemius muscle, 24 h or 48 h after the last training session. The train lasted for 7 weeks. The changes in the expressions of ERK1/2 and p-ERK1/2 were determined by Western blotting.The expression of ERK2 mRNA was determined by RT-PCR.</p><p><b>RESULTS</b>Exercise led to a marked increase in p-ERK1/2 of trained groups as compared with controls, and increased ERK1/2 protein expression of training 1.5 h/d, 24 h and 48 h after the last training session. ERK2 mRNA was increased by exercise 1 h/d, 24 h and exercise 1.5 h/d, 24 h and 48 h after the last training session. Glucose tolerance test found that blood insulin concentration was decreased with exercise training.</p><p><b>CONCLUSION</b>Endurance exercise could increase muscle responsiveness to insulin by improving the total ERK1/2 and p-ERK1/2, ERK2 mRNA expression.</p>