Depletion of delta 9 desaturase (EC 1.14.99.5) enzyme activity in growing rat during dietary protein restriction.
The effects of protein restriction on delta 9 desaturase (EC 1.14.99.5) activity were studied in growing rats. A control group was fed on a balanced diet (200 g casein/kg; BD) for 28 d. The experimental group was fed on the low-protein diet (20 g casein/kg; LP) for 26 d, then refed the balanced diet (BD-R) for 2 d. Rats were born to and suckled from normally fed dams. The enzyme activity was measured after 2 and 14 d of LP, and 26 d of LP plus 2 d of BD-R, by incubations in vitro of hepatic microsomal pellets with [1-14C]steric acid. The results indicated a decreased delta 9 desaturase activity after 2 and 14 d of LP of -33 and -43% respectively. Refeeding for 2 d was sufficient to super-repair this activity (+66%). The fatty acid composition of total liver lipids and microsomal phosphatidylethanolamines (PE) and phosphatidylcholines (PC) were also investigated; 18:0 decreased in total liver lipids at 14 d of LP, when 18:1n-9 increased. Stearic acid (18:0) increased in PC at 2 d of LP and in PE at 14 d of LP; oleic acid (18:1n-9) did not change. Therefore, it is concluded that a defect occurred in the bioconversion of 18:0 into 18:1n-9 by delta 9 desaturation during protein depletion. As oleic acid is accumulated in total liver lipids during LP, we speculate that this is due to a decreased oxidation or transport of this fatty acid.
Narce
M
M
Unité de Recherches en Nutrition Cellulaire et Métabolique, Faculté des Sciences Mirande, Dijon, France.
Poisson
J P
JP
Belleville
J
J
Chanussot
B
B
D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D006128:Growth / Q000502:physiology*; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D013230:Stearoyl-CoA Desaturase; D013997:Time Factors
D004044:Dietary Proteins; D044943:Fatty Acid Desaturases; D013230:Stearoyl-CoA Desaturase; C029627:delta-9 fatty acid desaturase