MECHANISMS OF HEPATIC PHOSPHATIDYLCHOLINE SYNTHESIS IN ADULT-RAT - EFFECTS OF PREGNANCY

Citation
Gc. Burdge et al., MECHANISMS OF HEPATIC PHOSPHATIDYLCHOLINE SYNTHESIS IN ADULT-RAT - EFFECTS OF PREGNANCY, Biochemical journal, 303, 1994, pp. 941-947
Citations number
28
Categorie Soggetti
Biology
Journal title
ISSN journal
02646021
Volume
303
Year of publication
1994
Part
3
Pages
941 - 947
Database
ISI
SICI code
0264-6021(1994)303:<941:MOHPSI>2.0.ZU;2-R
Abstract
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.