Polyunsaturated fatty acid biosynthesis from [1-14C]20:3 n-6 acid in rat cultured Sertoli cells. Linoleic acid effect.
Primary culture is a suitable system to study lipid metabolism and polyunsaturated fatty acid biosynthesis. Sertoli cell-enriched preparations were used to determine the fatty acid composition after 5 and 7 days in culture (serum free) as well as the uptake and metabolism of [1-14C]eicosa-8,11,14-trienoic acid. The addition of unlabeled linoleic acid (0.2 and 2.0 microg/ml) was also evaluated. Fatty acid methyl esters derived from cellular lipids were analyzed by gas liquid chromatography and radiochromatography. After 5 days in culture, cells had significantly less 18:2, 20:4, 22:5 and 24:5 and more 18:3, 20:3, 22:4 and 24:4 n-6 fatty acids than non-cultured cells. On day 7, an additional increment in 22:4 n-6 and a decrease in linoleic, gamma-linoleic and 24:4 n-6 fatty acids were observed. The presence of linoleic acid (low dose) produced a significant decrease in saturated and monounsaturated acids and an increase in 18:2, 20:4 and 22:5 n-6 fatty acids. At a high concentration almost all fatty acids belonging to 18:2 n-6 increased significantly. The drop in 20:4 n-6/20:3 n-6 ratio was considered as an indirect evidence of a Delta 5 desaturase activity depression. This assumption was corroborated by studying the transformation of [1-14C]eicosa-8,11,14-trienoic acid into 20:4, 22:4, 22:5, 24:4 and 24:5 n-6 fatty acids. We conclude that Sertoli cells after 7 days in culture evidenced changes in the fatty acid profile similar to those described under fat deprivation. The addition of linoleic acid reverted this pattern and indicated that the Delta 5 desaturase activity is a limiting step in the polyunsaturated fatty acid biosynthesis.
Hurtado de Catalfo
Graciela E
GE
Facultad de Ciencias Médicas, Instituto de Investigaciones Bioquímicas de La Plata-INIBIOLP, Calles 60 y 120, CC 455, 1900 La Plata, Argentina. gehurtado@hotmail.com
de Gomez Dumm
I Nelva T
IN
D015126:8,11,14-Eicosatrienoic Acid / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis* / Q000378:metabolism*; D019787:Linoleic Acid / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism*
D016895:Culture Media, Serum-Free; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D019787:Linoleic Acid; D015126:8,11,14-Eicosatrienoic Acid