Delta 5-desaturase activity in liver and brain microsomes during development of the pig.

Microsomes isolated from liver and brain tissue were assayed to examine transitions in metabolic capability to synthesize tetraenes and pentaenes by chain elongation-desaturation of C20:3(8,11,14) during the perinatal development of the pig. Rates of synthesis of tetraenes and pentaenes by chain elongation-desaturation of C20:3(8,11,14) were greatest in liver. During the latter half of gestation, the capability to synthesize tetraenes increased 7- or 23-fold on a per mg of microsomal protein basis for brain and liver respectively. Increase in the capacity to synthesize tetraenes from C20:3(8,11,14) suggests a significant transition in the activity of the delta 5-desaturase during the last half of gestation. These observations indicate that in liver and brain the capability to chain elongate-desaturate C18:2(9,12) to longer chain homologues increases significantly during early development as a function of transitions in the activity of the delta 5-desaturase.