Burton Tabaac -Differentiating Between Rate of Gastric Fluid, Bulk Intake and Calories as Signals for Control of Reproduction

Burton Tabaac
Department of Biological Sciences
Reproductive processes are inhibited by deficits in the availability of metabolic fuels, and this inhibition increases the chances of survival during energetic challenges and optimizes reproductive success by delaying energetically costly processes until fuels become available. The mechanisms that link energy availability to reproduction are unknown, and thus, in this study we tested the hypothesis that estrous cycles are most sensitive to sensory signals from bulk intake and gastric fill as opposed to signals from caloric intake or the availability of intracellular oxidizable fuels. The caloric content of a standard laboratory chow diet was diluted by 25, 50, or 75% with the largely indigestible fiber, cellulose, and fed to food-deprived, female hamsters throughout day 2 of the estrous cycle (ovulation and estrous behavior normally occur on day 4). The bulk intake/gastric fill hypothesis was not supported because bulk intake increased the more the diet was diluted, whereas the frequency of hamsters showing normal 4-day estrous cycles decreased with diet dilution, along with decreases in caloric intake and in plasma insulin concentrations. Rate of gastric emptying did not change significantly with diet dilution. Although consumption of a diluted diet significantly lengthened the estrous cycle, it did not affect incidence of pregnancy, litter size or pup weight. Thus, when hamsters ingest sufficient energy to support estrous behavior, they fully recover reproductive potential. In summary, neither bulk intake nor gastric fill provides critical signals necessary for reproduction, consistent with the idea that reproduction is primarily responsive fuel availability.
A Behavioral Neuroscience major studying at Lehigh for his final semester, Burton Tabaac has been working with Dr. Jill Schneider for the past three years and the subject of this poster was published this year. He is a three-year member of LU Emergency Medical Services and planning to attend medical school. And he has served as an EMT with an ambulance corp. And it is his dream to travel all over the world, seeing as many countries and different types of cultures as possible.