Effects of starvation and immobilization on imino acids in mouse brain and peripheral tissues

Effects of starvation and immobilization on the concentration of pipecolic acid and proline in mouse brain regions, liver, heart, kidney and blood plasma were analyzed. Pipecolic acid concentration in mouse brain and liver was increased after 24 or 48 h starvation, while proline concentration was not affected. Significant increases in levels of pipecolic acid were also observed in the rhombencephalon, liver and heart after 3 h immobilization. Proline in the blood plasma and kidney was decreased, while that in liver was increased, by the immobilization. Thus, the effect of such stress on concentration of pipecolic acid differed from that seen with proline. The possible involvement of pipecolic acid in synaptic mechanisms in the central nervous system and/or in pathogenesis of the diseases related to abnormal pipecolic acid metabolism should be given attention.