Relationship among dietary fats, fatty acid profile and expression of genes involved in testes function in Zucker (fa/fa) rats
Six week old male obese fa/fa Zucker rats (n=10/group) were fed four different diets enriched in linoleic acid (LA), α-linolenic acid (ALA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) (safflower oil, flaxseed oil, EPA, and DHA oils, respectively) for 8 weeks. Fatty acids were analyzed in major lipid classes in the testes. Global gene expression was analyzed using the Affymetrix Rat Gene 2.0 ST Array. Annotated gene sets from the normal and underdeveloped testes were analyzed using Ingenuity Pathway Analysis (IPA). In lipid analysis, n-3 diet supplementation decreased n-6: n-3 polyunsaturated fatty acid and n-6: n-3 very long chain fatty acids (VLCFA) in most lipid classes in comparison to the LA diet. ALA increased the level of DHA, but not to the same level as DHA diet. Compared to the normal sized testis, the underdeveloped testis showed a marked decrease in n-6 pentaenoic PUFA and VLCFA while increasing n-6 tetraenoic fatty acids. Out of the 3192 genes detected, 1121 and 309 were differentially expressed in the underdeveloped and normal testes, respectively. The IPA indicated that transcripts that are upregulated in the normal testes relative to underdeveloped testes are involved in triacylglycerol biosynthesis, sphingomyelin metabolism and phosphatidylglycerol biosynthesis. Transcripts upregulated in underdeveloped testes relative to normal testes are involved in production of nitric oxide and reactive oxygen species. Downstream effect analysis showed an increased trend towards reproductive system diseases and endocrine system disorders in the underdeveloped testes compared to the normal testes. In conclusion, these results indicate that testicular lipids and their metabolism are closely related with normal testis development and function.
Testes, Obesity, Transcriptome, Fatty acids, Lipids, EPA, DHA