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>

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>

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>

The inhibitory effect of chronic lead exposure on CA1 LTP and ERK2 activity in rat hippocampal area / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect of chronic lead exposure on rat hippocampal CA1 LTP and alpha-Ca2+ /calmodulin-dependent protein kinase II (alpha-CaM K II) activity in vivo.</p><p><b>METHODS</b>A stimulus bipolar electrode was placed on the Schaffer/Commissural fibers, with extra cellular microelectrode technique to record the population spike (PS) in the CA1 pyramidal, and we observed the changes of PS amplitude before and after the high frequency stimulation (HFS) of lower, mid and higher level lead exposure groups and the control group, respectively. The hippocampal CA1 alpha-CaM K II activity was determined by Western blots by using phosphorylation antibody.</p><p><b>RESULTS</b>The average changes of PS after HFS of the control group, the lower, mid and higher level lead exposure groups were 162.5%, 105.2%, 86.8%, 83.0%, respectively (P < 0.01 vs. control). Defined control a-CaM K II activity as 100, that the lower, mid and higher level lead exposure groups were 62.0 +/- 3.7, 50.8 +/- 4.0, 43.3 +/- 4.1 (P < 0.01).</p><p><b>CONCLUSION</b>Chronic lead exposure can inhibit CA1 LTP in vivo, and the decrease of alpha-CaMK II activity may play an important role in this mechanism.</p>

The function of ERK on Fas-mediated apoptotic signaling pathway of human gastric carcinoma cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To analyze the expression and functions of ERK (extracellular regulated kinase) in Fas-mediated apoptosis in gastric carcinoma cell line SGC-7901 and to elucidate the potential significance of this signaling pathway in tumor progression.</p><p><b>METHODS</b>Radioisotope labeling and Western blotting with special anti-ERK antibody were used to check ERK activity in SGC-7901 cell line after anti-Fas antibody treatment. Apoptosis induced by several treatment factors was evaluated by FACS can flow cytometer.</p><p><b>RESULTS</b>ERK activity increased and reached the peak at 30 min after treatment with anti-Fas antibody and decreased in PD98059 pretreated group. The number of sub-G(1) cell was 30.5% +/- 2.6% in PD98059 pretreated group, which was higher than anti-Fas treatment group and control group, respectively.</p><p><b>CONCLUSION</b>In gastric cancer cell line SGC-7901, Fas-induced ERK activation may suppress Fas-mediated apoptosis. Inhibition of ERK may enhance the sensitivity of SGC-7901 cells to Fas-mediated apoptosis. Fas-induced ERK activation may confer gastric cancer cells ability to escape the immune surveillance.</p>