Study data from Lehigh University provide new insights into behavior.(Report)

"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," scientists in the United States report (see also Behavior).

"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 ...