Expression of genes and localization of enzymes involved in polyunsaturated fatty acid synthesis in rabbit testis and epididymis

Cesare Castellini,Giuseppe Belmonte,Elena Moretti,Cinzia Signorini,Elisa Cotozzolo,Francesco Perini,Daria Noto,Giulia Collodel,Gabriele Brecchia,Emiliano Lasagna,Simona Mattioli,Alessandro Dal Bosco

doi:10.1038/s41598-022-06700-y

Abstract

The metabolism of polyunsaturated fatty acids (PUFAs) plays an important role in male reproduction. Linoleic and alpha-linolenic acids need to be provided in the diet and they are converted into long chain polyunsaturated fatty acids by steps of elongation and desaturation, exerted by elongases 2 (ELOVL2) and 5 (ELOVL5) and Δ5- (FADS1) and Δ6-desaturase (FADS2). This study aims to assess the gene expression and localization of enzymes involved in the synthesis of n-3 and n-6 long-chain PUFAs in control rabbits and those fed diets containing 10% extruded flaxseed. Enzyme and PUFA localization were assessed in the testes and epididymis by immunofluorescence. Testes showed high gene expression of FADS2, ELOVL2 and ELOVL5 and low expression of FADS1. Intermediate metabolites, enzymes and final products were differently found in Leydig, Sertoli and germinal cells. FADS2 was localized in interstitial cells and elongated spermatids; ELOVL5 in meiotic cells; FADS1 was evident in interstitial tissue, Sertoli cells and elongated spermatids; ELOVL2 in interstitial cells. Epididymal vesicles were positive for FADS1, ELOVL2 and ELOVL5 as well as docosahexaenoic, eicosapentaenoic, and arachidonic acids. This knowledge of fatty acids (FA) metabolism in spermatogenesis and the influence of diet on FA profile could help identify causes of male infertility, suggesting new personalized therapy.

Highlights

The metabolism of polyunsaturated fatty acids (PUFAs) plays an important role in male reproduction
LA and a large amount of precursor (ALA) are essential fatty acids, which need to be provided in the diet and they are converted into vital fatty acids (FAs, e.g. arachidonic [ARA C20:4n-6], eicosapentaenoic [EPA, C20:5n-3], n-3 DPA and DHA) by alternating steps of elongation and desaturation, exerted by elongases 2 (ELOVL2) and 5 (ELOVL5) and Δ5- (FADS1) and Δ6-desaturase (FADS2)[4]
In the testis of control rabbits, FADS2, acting on both LA and ALA, was clearly localized in interstitial cells (Fig. 2a); in the Flax group (FLAX) group, the fluorescence was highlighted in the elongated spermatids (Fig. 2b)

Summary

Introduction

The metabolism of polyunsaturated fatty acids (PUFAs) plays an important role in male reproduction. Linoleic and alpha-linolenic acids need to be provided in the diet and they are converted into long chain polyunsaturated fatty acids by steps of elongation and desaturation, exerted by elongases 2 (ELOVL2) and 5 (ELOVL5) and Δ5- (FADS1) and Δ6-desaturase (FADS2). Epididymal vesicles were positive for FADS1, ELOVL2 and ELOVL5 as well as docosahexaenoic, eicosapentaenoic, and arachidonic acids This knowledge of fatty acids (FA) metabolism in spermatogenesis and the influence of diet on FA profile could help identify causes of male infertility, suggesting new personalized therapy. LA and ALA are essential fatty acids, which need to be provided in the diet and they are converted into vital fatty acids (FAs, e.g. arachidonic [ARA C20:4n-6], eicosapentaenoic [EPA, C20:5n-3], n-3 DPA and DHA) by alternating steps of elongation and desaturation, exerted by elongases 2 (ELOVL2) and 5 (ELOVL5) and Δ5- (FADS1) and Δ6-desaturase (FADS2)[4]. Ingredients Dehydrated alfalfa meal Soybean meal 44% Barley meal Wheat bran Soybean oil Extruded flaxseed Beet molasses Calcium carbonate Calcium diphosphate Salt DL-methionine Vitamin-mineral premixa Digestible energy (Mj/kg)* Crude protein Ether extract Crude fibre Ash C16:0 C16:1 C18:0 C18:1 C18:2, LA C18:3 ALA

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