Effects of neonatal undernutrition of rats on the synthesis of phosphatidylcholine and phosphatidylethanolamine by microsomes from gray matter and white matter.

Undernutrition of rats during the suckling period produces deficits of glycerophospholipids in white matter but not in gray matter. The synthetic enzymes, CDPethanolamine:diacylglycerol phosphoethanolaminetransferase (EC 2.7.8.1) and CDPcholine:diacylglycerol phosphocholinetransferase (EC 2.7.8.2), were assayed in washed microsomal fractions from moderately and severely undernourished rats at 21 days of age. Deficits in brain weight were 14 and 31%, respectively. The transferase activities in white matter were more than 2-fold greater than in gray matter. Moderate undernutrition has less effect on total transferase activities but Km values were increased for CDPethanolamine with phosphoethanolamine transferase and for CDPcholine and dicaprin with phosphocholine transferase. Severe undernutrition produced by feeding the dams a diet with 4% protein gave deficits for phosphoethanolamine transferase of 52 and 55% and for phosphocholine transferase of 40 and 46% for gray matter and white matter, respectively. These results are consistent with the deficits of glycerophospholipids in white matter. Additional factors, such as synthetic rates in vivo and a reduction of turnover rates, must be sought for the sparing of the glycerophospholipid content of gray matter during undernutrition.