Utilization of 14C-tyrosine in brain and peripheral tissues of developmentally protein malnourished rats

MILLER, M., J. P. LEAHY, F. McCONVILLE, P. J. MORGANE AND O. RESNICK. Utilization of ¹⁴C-tyrosine inbrain and peripheral tissues of developmentally protein malnourished rats. BRAIN RES. BULL. 3(6) 681–686, 1978.—Prior studies of developmentally protein malnourished rats have reported substantial changes in brain and peripheral utilization of ¹⁴C-leucine, ¹⁴C-phenylalanine, and ¹⁴C-tryptophan. In the present study rats born to dams fed a low protein diet (8% casein) compared to the offspring of control rats fed a normal diet (25% casein) showed few significant differences in the uptake and incorporation of ¹⁴C-tyrosine into brain and peripheral tissues from birth to age 21 days. At birth, the 8% casein pups exhibited significant decreases in brain and peripheral tissue incorporation of tracer only at short post-injection times (10 and 20 min), but not at longer intervals (90 and 180 min). During ontogenetic development (Days 5–21), the 8% casein rats showed significant increases in uptake of ¹⁴C-tyrosine into the brain and peripheral tissues on Day 11 and a significantly higher percent incorporation of tracer into brain protein on Day 21 as compared to the 25% casein rats. For the most part, there were no significant changes in incorporation of radioactivity in peripheral tissues for the 2 diet groups on these post-birth days. Overall, the data indicates that developmental protein malnutrition causes relatively fewer changes in brain and peripheral utilization of the semi-essential amino acid tyrosine than those observed in previous studies with essential amino acids.