title: Metabolism of very long chain polyunsaturated fatty acids in isolated rat germ cells.
abstract: Which cell type is responsible for the high levels of very long chain polyunsaturated fatty acids in testis and whether this fatty acid pattern is a result of a local synthesis are not presently known. In this study, fatty acid conversion from 20:4n-6 to 22:5n-6 and from 20:5n-3 to 22:6n-3 was investigated in isolated rat germ cells incubated with [1-14C]-labeled fatty acids. The germ cells elongated the fatty acids from 20- to 22-carbon atoms and from 22- to 24-carbon atoms but had a low delta6 desaturation activity. Thus, little [14C]22:5n-6 and [14C]22:6n-3 were synthesized. When Sertoli cells were incubated with [1-14C]20:5n-3 for 24 h, an active fatty acid elongation and desaturation were observed. In vivo germ cells normally have a higher content of 22:5n-6 or 22:6n-3 than Sertoli cells. An eventual transport of essential fatty acids from Sertoli cells to germ cells was thus studied. Different co-culture systems were used in which germ cells were on one side of a filter and Sertoli cells on the opposite side. When isolated pachytene spermatocytes or round spermatids were added to the opposite side of a semipermeable filter, approximately 1 nmol [14C]22:6n-3 crossed the filter. Little of this was esterified in the germ cells. Similarly, in using [1-14C]20:4n-6 in identical experiments, very little [14C]22:5n-6 was esterified in germ cells on the opposite side of the filter. Although the very active synthesis of 22:5n-6 and 22:6n-3 observed in Sertoli cells suggests a transport of these compounds to germ cells, this was not experimentally determined.
authors.affiliation: Institute of Clinical Biochemistry, Andrology Laboratory, National Hospital, University of Oslo, Norway. kjetil.retterstol@rh.uio.no
authors.forename: K
authors.initials: K
authors.lastname: Retterstøl
authors.forename: T N
authors.initials: TN
authors.lastname: Tran
authors.forename: T B
authors.initials: TB
authors.lastname: Haugen
authors.forename: B O
authors.initials: BO
authors.lastname: Christophersen
mesh_terms: D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D018920:Coculture Techniques; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism*; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D008297:Male; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism*; D013090:Spermatocytes / Q000378:metabolism; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D008055:Lipids; D010743:Phospholipids