This study investigated the effects of AdipoRon, which is an agonist for adiponectin receptor 1 (AdipoR1) and AdipoR2, on the protein content, myotube diameter, and number of nuclei per myotube of C2C12 cells and skeletal muscle mass in C57BL/6J mice. AdipoRon suppressed the protein content, myotube diameter, and number of nuclei per myotube of C2C12 cells of C2C12 myotubes in a dose-dependent manner. Adiponectin-associated decline of protein content, diameter, and number of nuclei per myotube in C2C12 myotubes was partially rescued by knockdown of AdipoR1 and/or AdipoR2. Phosphorylation level of AMPK showed a trend to be increased by AdipoRon. A significant increase in phosphorylation level of AMPK was observed at 20 μM AdipoRon. Knockdown of AdipoR1 and/or AdipoR2 rescued AdipoRon-associated decrease in protein content of C2C12 myotubes. AdipoRon-associated increase in phosphorylation level of AMPK in C2C12 myotubes was suppressed by knockdown of AdipoR1 and/or AdipoR2. Successive intravenous injections of AdipoRon into mice caused a decrease in the wet weight of plantaris muscle (PLA), but not in soleus muscle (SOL). Mean fiber cross-sectional area of PLA, but not of SOL, was significantly decreased by AdipoRon administration. On the one hand, the expression level of phosphorylated AMPK and ubiquitinated protein in SOL and PLA muscles was upregulated by AdipoRon administration. On the other hand, AdipoRon administration induced no changes in the expression level of puromycin-labeled proteins in both SOL and PLA muscles. Expression level of adiponectin in extensor digitorum longus (EDL) muscle was increased by aging, but not in SOL muscle. Aging had no effect on the expression level of AdipoR1 and AdipoR2 in both muscles. Phosphorylation level of AMPK in EDL was increased by aging, but not SOL muscle. Results from this study suggest that high level of circulating adiponectin may induce skeletal muscle atrophy, especially fast-type muscle.
4 Burden AD. Management of psoriasis in childhood. Clin Exp Dermatol 1999; 24:341-5. 5 de Onis M, Blössner M. Prevalence and trends of overweight among preschool children in developing countries. Am J Clin Nutr 2000; 72:1032-9. 6 Janssen I, Katzmarzyk PT, Boyce WF et al. Health Behaviour in School-Aged Children Obesity Working Group. Comparison of overweight and obesity prevalence in school-aged youth from 34 countries and their relationships with physical activity and dietary patterns. Obes Rev 2005; 6:123-32. 7 Griffiths CE, Christophers E, Barker JN et al. A classification of psoriasis vulgaris according to phenotype. Br J Dermatol 2007; 156:258-62. 8 Poskitt EM, Cole TJ. Do fat babies stay fat? Br Med J 1977; 1:7-9. 9 Herron MD, Hinckley M, Hoffman MS et al. Impact of obesity and smoking on psoriasis presentation and management. Arch Dermatol 2005; 141:1527-34. 10 Naldi L, Parazzini F, Peli L et al. Dietary factors and the risk of psoriasis. Results of an Italian case-control study. Br J Dermatol 1996; 134:101-6.
The purpose of this study is to examine the relationship between approaches to learning and locus of control of students from the USA, Japan, and Taiwan. The results show that students from the USA utilized more rote memory learning compared to students from Japan and Taiwan, while students from Japan were more likely to be `Achieving' learners than peers from either the USA or Taiwan. `Deep Approaches' to learning, however, were similar across the three groups. Students from both Japan and Taiwan exhibited higher levels of external orientation than did students from the USA. Although cultural characteristics were reflected in students' locus of control orientation, there were no differences in students' deep processing understanding strategies as all students displayed low levels. School psychologists must therefore be aware that students from different Asian cultural backgrounds do not have a singular approach to learning or a singular locus of control orientation. The mediating role of cultural context in learning must be considered for individual students in order to implement appropriate and effective teaching strategies, techniques, and methods that promote deep level understanding for learners with differing cultural backgrounds.
The purpose of this study was to investigate the nuclear accumulation of heat shock protein 70 (HSP70), a molecular chaperonin in mouse skeletal muscle in response to aging, heat stress, and hindlimb unloading with or without reloading. Profiles of HSP70-specific nuclear transporter Hikeshi in skeletal muscles were also evaluated. Heat stress-associated nuclear accumulation of HSP70 was observed in slow soleus (SOL) and fast plantaris (PLA) muscles of young (10-week-old) mice. Mean nuclear expression level of HSP70 in slow medial gastrocnemius (MGAS) and PLA muscles of aged (100-week-old) mice increased ~4.8 and ~1.7 times, compared to that of young (10-week-old) mice. Reloading following 2-week hindlimb unloading caused accumulation of HSP70 in myonuclei in MGAS and PLA of young mice ( p < 0.05). However, reloading-associated nuclear accumulation of HSP70 was not observed in both types of muscles of aged mice. On the other hand, 2-week hindlimb unloading had no impact on the nuclear accumulation of HSP70 in both muscles of young and aged mice. Nuclear expression level of Hikeshi in both MGAS and PLA in mice was suppressed by aging. No significant changes in the nuclear Hikeshi in both muscles were induced by unloading with or without reloading. Results of this study indicate that the nuclear accumulation of HSP70 might show a protective response against cellular stresses in skeletal muscle and that the protective response may be suppressed by aging. Protective response to aging might depend on muscle fiber types.
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