effect of chronic protein malnutrition on trans-callosal evoked responses in the rat

Studies were carried out on the trans‐callosal evoked response in rats born of dams fed either a low (8%) or normal (25%) protein diet beginning 5 weeks prior to mating and throughout gestation and lactation. After weaning, pups were fed the same diets as their mothers. Bipolar (surface vs depth) stainless steel stimulating and recording electrodes were positioned at corresponding loci in the right and left sensorimotor cortices. Trans‐callosal evoked responses were measured under urethane anesthesia using twice‐threshold bipolar pulses of .1 msec duration at ages 13, 21, and 60–66 days. Evoked response latency was significantly greater in malnourished animals at 13 days of age, whereas at adulthood no latency differences were seen. Poststimulation excitability (15–100 msec range) was not significantly affected by the dietary treatment. These results are interpreted as corroborating previous reports on rats undernourished during development using sensory evoked potentials. By avoiding the use of extrinsic sensory stimulation, the present study demonstrates a dietary effect upon ontogeny of cortical evoked potentials independent of any possible effect on sensory receptor mechanisms.