Time-course effects of protein malnutrition on hepatic fatty acids delta 6 and delta 5 desaturation in the growing rat.
1. In growing rats, the time-course effects of giving a normal-protein diet (200 g casein/kg; NP) for 52 d, a low-protein diet (20 g casein/kg; LP) for 52 d and a LP diet for 26 d followed by balanced refeeding (200 g casein/kg; BR) for 26 d, on the fatty acid composition of liver total lipids and microsomal phospholipids were investigated together with delta 6- and delta 5-microsomal desaturase activities. 2. The oleic acid content (mg/g tissue) of liver total lipids increased progressively with the LP diet, while linoleic acid was increased only at days 7 and 52. 20:3 omega 6, 20:4 omega 6, 22:5 omega 6 and 22:6 omega 3 fatty acids decreased during the period on the LP diet. BR for 7 d was sufficient to restore the fatty acid composition of total lipids to control values. Changes in the fatty acid composition of liver microsomal L-alpha-phosphatidylcholines were observed only after 52 d on the LP diet; the proportions (% w/w total fatty acids) of 18:0, 20:3 omega 6 and 20:4 omega 6 fatty acids decreased while oleic acid increased. The fatty acid composition of L-alpha-phosphatidylethanolamines was less affected. 3. delta 6- and delta 5-desaturase activities decreased to 20-30% of their original values after 2 d on the LP diet; a smaller deficit prevailed after 14 d but disappeared after 25 d, to appear again after 52 d. As early as day 2 of BR, desaturase activities were greatly recovered and returned to control values at day 13. 4. The present work shows that modifications in microsomal delta 6- and delta 5-desaturase activities are not strictly paralleled by the changes in the composition of fatty acids of liver total lipids and microsomal phospholipids.
Narce
M
M
Laboratoire de Physiologie Animale et de la Nutrition, UA CNRS 273, Faculté des Sciences Mirande, Dijon, France.
Poisson
J P
JP
Belleville
J
J
Chanussot
B
B
D000818:Animals; D000090943:Delta-5 Fatty Acid Desaturase; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D050602:Linoleoyl-CoA Desaturase; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D009929:Organ Size; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011488:Protein Deficiency / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D015430:Weight Gain
D000090943:Delta-5 Fatty Acid Desaturase; D005227:Fatty Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase