Gc. Burdge et al., MECHANISMS OF HEPATIC PHOSPHATIDYLCHOLINE SYNTHESIS IN ADULT-RAT - EFFECTS OF PREGNANCY, Biochemical journal, 303, 1994, pp. 941-947
Late pregnancy in the rat (gestational ages 16-21 days) was accompanie
d by a specific increase in hepatic phosphatidylcholine (PC) and phosp
hatidylethanolamine (PE) molecular species containing C-16:0 at the sn
-1 position and polyunsaturated essential fatty acids (PUFA), in parti
cular C-22:6(n-3), at the sn-2 position. Incorporation of either CDP:[
Me-C-14]choline or CDP: [1,2-C-14]ethanolamine into hepatic microsomal
sn-1 C-16:0 PC or PE molecular species in vitro was greater at term t
han in nonpregnant animals, suggesting modifications to the compositio
n of specific diacylglycerol (DAG) pools destined for synthesis of eit
her PC or PE. Also, incorporation of [Me-C-14]choline or [Me(14)C]meth
ionine into hepatic PC in vivo over 6 h in term pregnant rats was cons
istent with decreased phospholipase A(1)-dependent acyl remodelling of
sn-1 C-16:0 to sn-1 C-18:0 molecular species. There was, however, no
evidence to support any change to the specificity of acyl remodelling.
The rate of PC synthesis by the de novo pathway in vivo was increased
in term liver compared with non-pregnant animals, accompanied by incr
eased cholinephosphotransferase activity in vitro in d21 liver microso
mes. The rate of PC synthesis by PE N-methylation did not appear to ch
ange during pregnancy. Changes in composition of plasma PC species at
term reflected those of newly synthesized hepatic PC. Our data suggest
supply of PUFA to the developing fetal rat is the result of specific
adaptations to maternal hepatic phospholipid biosynthesis rather than
passive transfer from the maternal diet.