THE EFFECTS OF UNDERNUTRITION UPON THE ENERGY RESERVE OF THE BRAIN AND UPON OTHER SELECTED METABOLIC INTERMEDIATES IN BRAINS AND LIVERS OF INFANT RATS1

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Abstract
—Rats undernourished from the first to the ninth day of life exhibited no decrease in the energy reserve (P‐creatine, ATP, glucose and glycogen) of the brain, although they underwent a 41 per cent decrease in body weight. The apparent increase in the cerebral levels of glucose‐6‐phosphate and the decreases in hepatic glucose and lactate in the starved animals were probably a consequence of the fact that they froze faster than the control animals rather than of any essential differences in vivo. However, decreases in cerebral glutamate (11 per cent) and hepatic glutamate (33 per cent) in the undernourished animals cannot be explained on this basis. Possible explanations for this decrease in cerebral glutamate content are: a decreased supply of glutamate from the liver, a decreased synthesis of glutamate by the brain, or an increased use of glutamate as an energy source. Since levels of glutamate in the brain increase progressively during the first weeks of life, another interesting possibility is that the lower level of cerebral glutamate in undernourished rats represents a biochemical indicator of a delay in the maturation of specific morphological components which are rich in glutamate and are characteristic of the brain.