Kjetil Retterstøl , Trine B. Haugen , Berit Woldseth , Bjørn O. Christophersen
{"title":"未成熟大鼠睾丸细胞n-9、n-6和n-3脂肪酸代谢的比较研究","authors":"Kjetil Retterstøl , Trine B. Haugen , Berit Woldseth , Bjørn O. Christophersen","doi":"10.1016/S0005-2760(98)00021-6","DOIUrl":null,"url":null,"abstract":"<div><p>Dietary 18 and 20-carbon fatty acids of the <em>n</em>-6 and the <em>n</em>-3 families are metabolized to 22:5,<em>n</em>-6 and 22:6,<em>n</em>-3 by a sequence of specific desaturases and chain elongation via 24-carbon intermediates. This pathway is regulated so that more 22:6,<em>n</em>-3 than 22:5,<em>n</em>-6 is found in the tissues. Rat testis is an exception since 22:5,<em>n</em>-6 is present in large proportions in this organ. Therefore rat testis appears to be interesting for studies of the detailed synthesis of 22:5,<em>n</em>-6 compared with that of 22:6,<em>n</em>-3. By using fresh preparations of rat testicular cells from 19-day-old rats enriched in Sertoli cells, we compared the metabolism of 1-<sup>14</sup>C-labelled <em>n</em>-3, <em>n</em>-6 and <em>n</em>-9 fatty acids. The testicular cells actively synthesized 22:6,<em>n</em>-3 and 22:5,<em>n</em>-6, but not 22:4,<em>n</em>-9 from the 18 and 20-carbon precursors. Of 200 mol <sup>14</sup>C-labelled C<sub>18</sub> and C<sub>20</sub> fatty acids added initially, approximately 20-40 mol were found as 24-carbon intermediates after 24 h of incubation. This indicates that the balanced capacity of elongation, desaturation and chain shortening favours the accumulation of 24-carbon intermediates in these cells. One exception was [1-<sup>14</sup>C]20:3,<em>n</em>-9 which was efficiently elongated to 22:3,<em>n</em>-9 but not to C<sub>24</sub> fatty acids. Our data suggests that the poor elongation of <em>n</em>-9 fatty acids from C<sub>22<sup>−</sup></sub> to C<sub>24</sub> may be an important hindrance in the synthesis of 22:4,<em>n</em>-9. The efficient synthesis of 22:5,<em>n</em>-6 may also partly explain why this is the major 22-carbon fatty acid in rat testis.</p></div>","PeriodicalId":100162,"journal":{"name":"Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1998-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0005-2760(98)00021-6","citationCount":"27","resultStr":"{\"title\":\"A comparative study of the metabolism of n-9, n-6 and n-3 fatty acids in testicular cells from immature rat\",\"authors\":\"Kjetil Retterstøl , Trine B. Haugen , Berit Woldseth , Bjørn O. Christophersen\",\"doi\":\"10.1016/S0005-2760(98)00021-6\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Dietary 18 and 20-carbon fatty acids of the <em>n</em>-6 and the <em>n</em>-3 families are metabolized to 22:5,<em>n</em>-6 and 22:6,<em>n</em>-3 by a sequence of specific desaturases and chain elongation via 24-carbon intermediates. This pathway is regulated so that more 22:6,<em>n</em>-3 than 22:5,<em>n</em>-6 is found in the tissues. Rat testis is an exception since 22:5,<em>n</em>-6 is present in large proportions in this organ. Therefore rat testis appears to be interesting for studies of the detailed synthesis of 22:5,<em>n</em>-6 compared with that of 22:6,<em>n</em>-3. By using fresh preparations of rat testicular cells from 19-day-old rats enriched in Sertoli cells, we compared the metabolism of 1-<sup>14</sup>C-labelled <em>n</em>-3, <em>n</em>-6 and <em>n</em>-9 fatty acids. The testicular cells actively synthesized 22:6,<em>n</em>-3 and 22:5,<em>n</em>-6, but not 22:4,<em>n</em>-9 from the 18 and 20-carbon precursors. Of 200 mol <sup>14</sup>C-labelled C<sub>18</sub> and C<sub>20</sub> fatty acids added initially, approximately 20-40 mol were found as 24-carbon intermediates after 24 h of incubation. This indicates that the balanced capacity of elongation, desaturation and chain shortening favours the accumulation of 24-carbon intermediates in these cells. One exception was [1-<sup>14</sup>C]20:3,<em>n</em>-9 which was efficiently elongated to 22:3,<em>n</em>-9 but not to C<sub>24</sub> fatty acids. Our data suggests that the poor elongation of <em>n</em>-9 fatty acids from C<sub>22<sup>−</sup></sub> to C<sub>24</sub> may be an important hindrance in the synthesis of 22:4,<em>n</em>-9. The efficient synthesis of 22:5,<em>n</em>-6 may also partly explain why this is the major 22-carbon fatty acid in rat testis.</p></div>\",\"PeriodicalId\":100162,\"journal\":{\"name\":\"Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1998-05-20\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/S0005-2760(98)00021-6\",\"citationCount\":\"27\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0005276098000216\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0005276098000216","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
A comparative study of the metabolism of n-9, n-6 and n-3 fatty acids in testicular cells from immature rat
Dietary 18 and 20-carbon fatty acids of the n-6 and the n-3 families are metabolized to 22:5,n-6 and 22:6,n-3 by a sequence of specific desaturases and chain elongation via 24-carbon intermediates. This pathway is regulated so that more 22:6,n-3 than 22:5,n-6 is found in the tissues. Rat testis is an exception since 22:5,n-6 is present in large proportions in this organ. Therefore rat testis appears to be interesting for studies of the detailed synthesis of 22:5,n-6 compared with that of 22:6,n-3. By using fresh preparations of rat testicular cells from 19-day-old rats enriched in Sertoli cells, we compared the metabolism of 1-14C-labelled n-3, n-6 and n-9 fatty acids. The testicular cells actively synthesized 22:6,n-3 and 22:5,n-6, but not 22:4,n-9 from the 18 and 20-carbon precursors. Of 200 mol 14C-labelled C18 and C20 fatty acids added initially, approximately 20-40 mol were found as 24-carbon intermediates after 24 h of incubation. This indicates that the balanced capacity of elongation, desaturation and chain shortening favours the accumulation of 24-carbon intermediates in these cells. One exception was [1-14C]20:3,n-9 which was efficiently elongated to 22:3,n-9 but not to C24 fatty acids. Our data suggests that the poor elongation of n-9 fatty acids from C22− to C24 may be an important hindrance in the synthesis of 22:4,n-9. The efficient synthesis of 22:5,n-6 may also partly explain why this is the major 22-carbon fatty acid in rat testis.