AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 1 106-R110, Copyright © 1985 by American Physiological Society
Characterization of muscles from aspartic acid obese rats
J. A. Burbach, E. H. Schlenker and M. Goldman
This study was undertaken to determine whether changes in muscle mass,
muscle fiber diameter, or shifts in fiber type occur in the aspartic
acid-injected rat, an animal model of hypothalamically induced obesity. We
found that diaphragm, gastrocnemius, and soleus muscle mass was 140, 149,
and 171% greater, respectively, in control compared with aspartic
acid-injected rats. No differences were noted in heart weights. Significant
reductions in mean fiber diameter of aspartic compared with control rats
were present in each skeletal muscle. Furthermore, significant size
reductions were noted for each fiber type in the diaphragm, with
fast-glycolytic fibers showing the greatest reduction compared with
controls at both 7 and 12 mo. Fiber type composition within the diaphragm
did not differ between groups but showed a change with age. These results
are compared with genetic models of obesity, the Zucker rat and the ob/ob
mouse, as well as the ventromedial hypothalamic lesioned rat and the gold
thioglucose mouse. Based on these results, the aspartic rat appears more
similar to the two genetic models of obesity and also mimics some of the
effects of malnutrition in rodents.
