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BACKGROUND:Some studies indicate that PI3K/Akt signaling pathway is associated with the expression of glucose transporter 4 (GLUT4) and the function of cAMP response element binding protein (CREB) in skeletal muscle. However, it is stil unclear whether PI3K/Akt signaling pathway has the effects on CREB and GLUT4 in skeletal muscle of the rats with high-fat diet and treadmil exercise. OBJECTIVE:To investigate whether PI3K/Akt signaling pathway has the effects on CREB and GLUT4 in gastrocnemius muscle of the rats with high-fat diet and treadmil exercise. METHODS:A total of 70 rats were fed with normal diet for 2 weeks, and randomly divided into common feed group (n=20) and high-fat feed group (n=50). Rats in both groups were respectively fed with common feed and high-fat feed for 8 weeks. The rats in the common feed group were equaly assigned to common feed quiet group and common feed exercise group. 20 rats from the high-fat feed group whose body weight was 1.4 times of common rats were randomly and equaly assigned to obese quiet group and obese exercise group. Rats in the quiet groups did not do exercises. Rats in the exercise groups received adaptive sports for 1 week and medium-intensity treadmil exercise for 8 weeks. RESULTS AND CONCLUSION:(1) Impairments of PI3K/Akt signaling pathway appeared in obese rats, however, the quantity of GLUT4 expression did not change obviously in gastrocnemius muscles of obese rats. The reasons for the decrease of the nuclear protein CREB level of gastrocnemius muscles of obese rats might be related to the decrease of pAkt-Ser473 level. (2) The increase of the quantity of GLUT4 expression was accompanied by significantly up-regulated pAkt-Ser473 level by exercise intervention in gastrocnemius muscles of obese rats. Exercise intervention significantly increased the expression of nuclear protein CREB in gastrocnemius muscles of chow-fed rats and obese rats, which was consistent with the changes of pAkt-Ser473. These findings suggest that pAkt-Ser473 can play an important role in the effects of high-fat diet and exercise intervention on GLUT4 and CREB protein expression in gastrocnemius muscles of obese rats.
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AIM: To investigate the heterogeneity of basal intracellular free calcium concentration( i) in peritoneal macrophages(PM) and whether it is relative to the reactivity of PM at the single cell level. METHODS: i implicated stimulated were measured by fluorescent microscopic imaging system after loading with fluorescent probe fura-2/AM. Superoxide(O _2)produced by single PM was determined by modified NBT test. RESULTS: The values of basal i determined in 392 PMs of 7 mice showed normal distribution [(54?24) nmol/L, n=392] with wide range(less than 20 nmol/L to more than 100 nmol/L), among which about 50% were in the range of 40-60 nmol/L. When stimulated with PMA or fMLP, i was increased, the peak values were positively correlated with the basal i in one mouse(PMA stimulated cells: r=0.52, P
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AIM: To investigate the signal transduction mechanism of rapid effect of corticosterone. METHODS: With liquid scintillation technique, the effect of corticosterone on glycine uptake in C6 cells was examined. RESULTS: The bovine serum album in coupled with corticosterone had the same effect as corticosterone 21-sulfate(B); Neomycin partially blocked the effect of B in C6 cells; GDP-?-S attenuated the effects of B on glycine uptake in C6 cells; Chelerythrine chloride (Chelery) partially blocked the effect of B in C6 cells; H 89 had no influence on the effect of B in C6 cells. The Km and Vmax of effect of B on glycine uptake in C6 cells were different from those in SK-N-SH cells. CONCLUSION: PKC, instead of PKA, was involved in the signal transduction of the rapid effect of B on glycine uptake in C6 cells. The converse effects of B on C6 cells and SK-N-SH cells resulted from different transportation system in two kinds of cells.
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Objective: To investigate the effect of glucocorticoid on high K + induced catecholamine secretion in PC12 cells. Methods: High performance liquid chromatography with electrochemical detection were used to measure catecholamine secreted by PC12 cells. Results:(1) After PC12 cells were pretreated with various concentration of corticosterone at 37℃ for 5 min and then stimulated with various concentration of high K + for different time periods, the inhibitory effect of corticosterone on catecholamine secretion was found in a dose dependent manner. (2) When the duration of high K + treatment was prolonged, the inhibitory effect of corticosterone on catecholamine secretion tended to be attenuated. Conclusion: Glucocorticoid can rapidly inhibit the catecholamine secretion induced by high K + in PC12 cells. [
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0.05). Conclusion Treadmill running with low load for 1 week can enhance neurogenesis in the dentate gyrus of young SD rats.