Springer Online Journal Archives 1860-2000
Abstract In mice subjected to long uninterrupted avoidance sessions (1,500 trials) a clear decrement of performance was evident after the first 500–600 trials. Mice subjected to a 24 h fast showed a more rapid decrement of performance during the session following the fasting period than that evident in the same group fed ad libitum. When the effects of feeding casein, glucose or different amino acids were assessed, only casein, glucose or serine prevented the impairment of performance while the most toxic amino acids, i.e. histidine, methionine and tryptophan diminished the performance below that obtained by fasting. Casein, glucose and serine were the only diets that maintained blood glucose levels within the normal range. Feding experiments showed that serine was the most acceptable aminoacid to the mice indicating that it was unique in maintaining performance because it is the only amino acid that is both palatable and readily gluconeogenic.
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