Abstract # 61:

Scheduled for Thursday, June 18, 2015 04:55 PM-05:10 PM: (Cascade H) Oral Presentation


M. N. Muchlinski, H. Vollrath and H. Hemingway
University of Kentucky, Department of Anatomy and Neurobiology, Lexington, Kentucky 40536-0098, USA
     The Growth Regulatory Hypothesis states that brain growth governs somatic growth. Muscle as a percentage of body mass (%TBM) varies during adulthood, but the amount of variation in muscle as a %TBM is most notable during early development. In humans, there is a marked inverse relationship between the rate of growth (and glucose consumption) in the brain and the rate of growth in skeletal muscle, with a pronounced shift in resource allocation directly preceding puberty. This shift occurs because early in life, brain growth is the focus of glucose consumption. This study evaluates if a similar relationship can be found in non-human primates. We dissected an ontogentic sample of primates: Galago, Hapalemur, Saimiri, and Pan. We collected total muscle mass values and endocranial volume. Using molar eruption as a marker of adult brain size in subadults, we examined how muscle mass as a %TBM changes as individuals age. We observed a shift in muscle mass soon after the first lower molar erupts. In Pan, muscle as a %TBM averages 18% early in life, while it averaged 35% in adults. The same patter was seen in Galago (10.1% vs. 36.7%), Hapalemur (11.2% vs. 24.2%), and Saimiri (9.1% vs. 29.3%). Examining how muscle mass changes ontogenetically is another method of evaluating the proposed metabolic trade-off between brain size and muscle mass.